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Editorials

Chest. 1997;111(6):1477. doi:10.1378/chest.111.6.1477
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Chest. 1997;111(6):1478. doi:10.1378/chest.111.6.1478
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Chest. 1997;111(6):1478-1479. doi:10.1378/chest.111.6.1478-a
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Chest. 1997;111(6):1479-1482. doi:10.1378/chest.111.6.1479
Chest. 1997;111(6):1482-1483. doi:10.1378/chest.111.6.1482
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Chest. 1997;111(6):1483-1486. doi:10.1378/chest.111.6.1483
Chest. 1997;111(6):1486-1487. doi:10.1378/chest.111.6.1486
Abstract
Topics: lung cancer

Articles

Chest. 1997;111(6):1488-1493. doi:10.1378/chest.111.6.1488

Objective: Sleep-disordered breathing (SDB) is common in congestive heart failure. While isolated diastolic heart failure (DHF) accounts for up to a third of all cases of congestive heart failure, the prevalence of SDB in DHF is unknown. We aim to determine the prevalence and characteristics of SDB in a group of patients with symptomatic DHF.

Methods: Twenty subjects with symptomatic DHF (New York Heart Association class II or III) and isolated diastolic dysfunction on echocardiography were assessed with lung function tests, modified sleep and health questionnaire, and overnight polysomnography. Significant SDB was defined as an apnea/hypopnea index (AHI) >10.

Results: Thirteen female and seven male subjects (mean age, 65±6.0 years; mean body mass index (BMI), 28±3.2) were evaluated, of whom 17 (85%) had a diagnosis of hypertension. Overall sleep quality was poor, with fragmentation and frequent arousals associated with respiratory events. Fifty-five percent of the patients had significant SDB, mainly obstructive apneas. BMI and the prevalence of hypertension were similar in patients with and without SDB. The deceleration time, an index of diastolic dysfunction, was more prolonged in the group with SDB (236±40 ms vs 282±31 ms; p<0.05). As a group, a lower minimum percentage arterial oxygen saturation during sleep, but not the AHI was associated with more severe degree of diastolic dysfunction on echocardiogram, including a lower ratio between the early peak transmittal flow velocity and the late peak atrial systolic velocity (rho=0.57; p<0.05) and a prolonged isovolumic relaxation time (rho=−0.54; p<0.05).

Conclusions: SDB is common in patients with DHF. Patients with DHF and SDB may be associated with worse diastolic dysfunction than those without SDB, although a causal relationship remains to be established.

Chest. 1997;111(6):1494-1499. doi:10.1378/chest.111.6.1494

Study objective: To determine the sleep/wake habits of patients diagnosed as having obstructive sleep apnea (ie, respiratory event index [REI] ≥5).

Design: Case series with prospective data collection to determine the relationship among sleepiness, REI, and sleep/wake habits. Patients were grouped according to their multiple sleep latency test (MSLT) results (≤5 and >5) and REI (mild REI ≤20; moderate REI >20 but ≤60; and severe REI >60).

Setting: An American Sleep Disorders Association-accredited sleep laboratory.

Patients: Three hundred ninety (325 male, 65 female) consecutive patients seen between June 1993 and January 1995 for evaluation of sleep apnea. This included a sleep, medical, and psychiatric evaluation followed by a physical examination. Sleep histories and sleep/wake habits were recorded by a physician trained in sleep medicine. Polysomnographic evaluation consisted of a nocturnal clinical polysomnogram (CPSG) and an MSLT on the following day. Of 390 patients, 268 completed polysomnographic evaluation (CPSG and MSLT).

Measurements and results: Sleepy (MSLT ≤5) patients with mild (REI ≤20) and moderate apnea (REI >20 ≤60) reported spending significantly less time in bed than sleepy patients with severe apnea (REI >60). Those with severe apnea (REI >60) reported napping significantly more and experienced a more severe disruption of their routine daily activities because of sleepiness when compared with mild and moderate OSA patients.

Conclusions: These data suggest that sleep habits have an important modulatory effect on the level of sleepiness and this effect is lost as the severity of sleep-disordered breathing increases.

Chest. 1997;111(6):1500-1504. doi:10.1378/chest.111.6.1500

Background: Upper airway inflammation is present in patients with obstructive sleep apnea (OSA).

Objective: To determine whether exhaled pentane and nitric oxide (NO) levels, two nonspecific markers of inflammation, are increased in patients with OSA.

Methods: Exhaled nasal and oral pentane and NO levels were determined before and after sleep in 20 patients with OSA (apnea-hypopnea index, 48±7; mean±SEM) and eight healthy control subjects.

Results: In patients with OSA, exhaled nasal and oral pentane levels after sleep were significantly higher than presleep values (6.1±1.2 nM vs 3.4±0.4 nM, and 7.0±1.3 nM vs 4.2±0.4 nM, respectively; p<0.05). Likewise, exhaled nasal and oral NO levels after sleep were significantly higher than presleep values in patients with OSA (39.7±3.8 ppb vs 28.4±2.9 ppb and 10.9±1.5 ppb vs 6.6±0.8 ppb, respectively; p<0.05). By contrast, there were no significant differences in exhaled nasal and oral pentane, and nasal NO levels before and after sleep in control subjects. Exhaled oral NO levels were significantly increased after sleep in comparison to presleep values in control subjects (p<0.05).

Conclusion: Exhaled nasal pentane and NO levels are increased after sleep in patients with moderate-severe OSA. These data suggest that upper airway inflammation is present in these patients after sleep.

Chest. 1997;111(6):1505-1508. doi:10.1378/chest.111.6.1505

Study objective: Nebulizer systems used to generate therapeutic aerosols vary in their ability to deliver medication to the airway. In a recent study in 17 adults with stable asthma, albuterol given using an ultrasonic nebulizer (UN) appeared to produce greater bronchodilatation than the same dose of albuterol given by a jet nebulizer (JN). The purpose of this study was to determine if the UN used in that study would produce a better bronchodilator response in children with acute asthma than the JN system that has been in use at Cardinal Glennon Children's Hospital.

Design: Randomized, prospective, unblinded study.

Setting: An urban university children's hospital emergency department.

Participants: One hundred thirteen children, aged 7 to 16 years, who presented for treatment of acute moderately severe asthma completed this study.

Interventions: After randomization and exclusion of dropouts, 46 children received albuterol by UN and 67 were treated by JN.

Measurements: Pulmonary function tests (PFTs) by spirometry, pulse oximetry, and symptom score at baseline and at 15 and 30 min following a single prescribed treatment.

Results: PFT on entry to the study was the same in both groups (FEV1; p>0.97). The change in FEV1 after therapy (UN+0.22 L vs JN+0.37 L) was significant (p<0.05) and favored JN. There was no difference in the improvement in pulmonary function between JN and UN therapy in children with an initial FEV1/FVC>75% predicted but when FEV1/FVC<75%, the improvement in FEV1 again favored the JN (UN+0.2 vs JN+0.47; p<0.05).

Conclusion: For the treatment of acute exacerbations of asthma in children, there is no greater bronchodilator response when albuterol is administered by a UN than by a JN.

Chest. 1997;111(6):1509-1513. doi:10.1378/chest.111.6.1509

Background: In comparison to β-agonist drugs, which are the primary bronchodilator drugs in current use in asthma, both oral theophylline and inhaled ipratropium have a weaker bronchodilating action in asthma. Although a number of studies have shown an additive effect of ipratropium in combination with β-agonist bronchodilator drugs in asthmatics, to our knowledge, the effects of combined treatment with ipratropium and theophylline have not been assessed.

Study objective: To assess whether the combination of oral theophylline and inhaled ipratropium has an additive bronchodilator effect in asthmatics.

Design: Double-blind, placebo-controlled, crossover study.

Subjects: Nineteen patients (8 male, 11 female) with mild-to-moderate stable asthma.

Methods: Initially the optimal single oral dose of theophylline required to achieve therapeutic blood levels (10 to 20 µg/mL) was established in each patient. They then returned at varying intervals on 4 subsequent days. On each day, they received, in a random, placebo-controlled, double-blind, crossover design, one of four different therapies: oral and inhaled placebo; oral theophylline at the established optimal dose (range, 300 to 700 mg) plus inhaled placebo; oral placebo plus inhaled (40 µg) ipratropium; and the combination of theophylline and ipratropium. Spirometry was performed at baseline and at 15 min, 30 min, and hourly intervals for 6 h after therapy.

Results: Each drug regimen resulted in a significant (p<0.05) increase in FEV1, but the combined regimen resulted in a significantly greater bronchodilation (p<0.05) over either ipratropium or theophylline alone (FEV1=3.00±0.75 L vs 2.48±0.77 L vs 2.61±0.72 L, respectively, at 3 h postdrug).

Conclusions: There was a significant, early, sustained additive bronchodilator effect of the combination therapy; there were no untoward side effects. These findings indicate that the addition of inhaled ipratropium to oral theophylline provides greater bronchodilation than either drug alone and may be a useful therapeutic modality in asthma.

Chest. 1997;111(6):1514-1518. doi:10.1378/chest.111.6.1514

Study objective: Systemic administration of β-agonist and anticholinergic drugs markedly impair normal autonomic heart rate control. The purpose of this study was to quantify and compare the effects of therapeutic doses of inhaled albuterol and ipratropium on autonomic control of the cardiovascular system.

Design: Randomized, double-blind, placebo-controlled, crossover design study.

Setting: Tertiary-care hospital.

Subjects: Twelve healthy male volunteers.

Interventions: Subjects self-administered four puffs through a spacer device from one of three identical inhalers containing albuterol (100 µg per puff), ipratropium (20 µg per puff), or placebo in three different testing sessions.

Measurements: ECG and noninvasive continuous BP traces were recorded at baseline and from 45 to 75 min after administration of the drug. Autonomic control of the cardiovascular system was quantified by analysis of spontaneous baroreflex sensitivity and power spectral analysis of heart rate variability.

Results: Neither albuterol nor ipratropium caused a significant alteration in baroreflex sensitivity, normalized low-power frequency, or normalized high-power frequency. No adverse effects were reported by subjects.

Conclusions: Inhalation of four puffs of albuterol (400 µg) or ipratropium (80 µg) does not alter the autonomic control of the cardiovascular system in young, healthy male subjects.

Chest. 1997;111(6):1519-1525. doi:10.1378/chest.111.6.1519

Objectives: To assess, in acutely ill asthmatic children, the feasibility of obtaining reproducible measurements of two independent lung function tests, namely spirometry and respiratory resistance, using the forced oscillation technique (Rfo).

Design/setting: A prospective observational study of 150 previously untrained children, aged 2 to 17 years, treated for acute asthma in a tertiary-care pediatric emergency department.

Measurements: Following a standardized physical examination, three measurements of respiratory resistance by forced oscillation were attempted at 8 Hz (Rfo8) and at 16 Hz (Rfo16), followed by spirometry, all using the same instrument (Custo Vit R; Custo Med; Munich, Germany).

Results: On the initial assessment, 98 (65%) children, aged 2 to 17 years, were able to reproducibly perform the Rfo8 measurement, 77 (51%) were able to reproducibly perform the Rfo16 measurement, while only 65 (43%) subjects managed to reliably perform spirometry. A notable proportion of preschool-aged children cooperated with the Rfo8 technique: 19% of 3-year-olds, 40% of 4-year-olds, and 83% of 5-year-olds. The superior success rate with Rfo8 as compared with spirometry was seen in all age groups but was most striking both in preschoolers (relative risk [RR]=10.5; 95% confidence interval [CI], 8.0 to 13.8) and in children aged 6 to 9 years (RR=1.28; 95% CI, 1.18 to 1.39). Rfo8 values correlated significantly with clinical markers of asthma severity such as respiratory rate (r=0.38) and heart rate (r=0.23) as well as with FEV1 values (r2=0.73).

Conclusions: This study demonstrates the feasibility of obtaining reproducible measurements of respiratory resistance in a notable proportion of untrained, acutely ill, asthmatic children. The forced oscillation technique appears as an attractive alternative to objectively assess lung function in children too young or too ill to cooperate with spirometry.

Chest. 1997;111(6):1526-1532. doi:10.1378/chest.111.6.1526

Associations among dust exposure, smoking habits, and demographic factors and longitudinal changes of lung function were assessed among male steel workers. Cohort descriptive data analysis was conducted in 541 steel workers who had performed spirometry at least twice between 1982 and 1991 (mean follow-up, 6.1 years). The annual change (slope) in FVC, FEV1 FEV1/FVC%, and in body weight was determined by simple linear regression. The Pearson correlation coefficient between weight change and spirometry changes was calculated. Comparisons were also done in 75 pairs of steel workers matched by age, height, initial FEV1 and smoking status, but whose FEV1 declines differed by ≥60 mL/yr. The FEV1 and FVC declined an average of 44 and 50 mL/yr, respectively, for the cohort as a whole. The FEV1 and FVC declined 52 and 54 mL/yr for current smokers, 43 and 53 mL/yr for ex-smokers, and 36 and 43 mL/yr for nonsmokers, respectively. Increasing weight was highly correlated with accelerated decline in lung function (p<0.0001). In the matched pairs, mean slopes for FVC, FEV1 and FEV1/FVC ratio were −96 mL/yr, −95 mL/yr, and −0.40%/yr for the rapid decliners; and +5 mL/yr, +10 mL/yr, and +0.10%/yr for their partners (p<0.0001). Matched pair comparisons showed that the rapid decliners averaged a 4.313 kg weight gain, while their partners gained 1.044 kg during the follow-up period. The slope of weight gain was 0.708 kg/yr for rapid decliners and 0.191 kg/yr for comparison workers (p<0.0036). Weight gain, in addition to aging and cigarette smoking, was found to be associated with the longitudinal rate of decline in FVC, FEV1 and FEV1/FVC ratio.

Chest. 1997;111(6):1533-1535. doi:10.1378/chest.111.6.1533

Study objective: To assess the potential utility of specific airway conductance (sGaw) in detecting small airways dysfunction, the postlung-transplant bronchiolitis obliterans syndrome (BOS) was used as a model of small airways dysfunction. BOS is defined as an otherwise unexplained 20% reduction in FEV1. We hypothesized that if sGaw is sensitive to small airways dysfunction, it should decrease before the decline in FEV1.

Design/methods: The pulmonary function test and sGaw measurements of patients who underwent heart-lung or bilateral lung transplantation between May 1981 and January 1993 were reviewed. Patients with and without BOS were identified. A significant decrease in sGaw was defined as a 20% fall from baseline.

Results: Twenty-six BOS and 15 non-BOS patients had at least three sGaw measurements such that trends could be examined. Eleven of the 26 BOS patients (42%) had a significant decrease in sGaw before a 20% decrease in FEV1, as compared to 2 of the 15 non-BOS patients (13%) (p=0.08). In comparison, 12 of the 26 BOS patients (46%) and 4 of the 15 non-BOS patients (27%) had a significant decrease in forced expiratory flow at 25 to 75% of the forced lung volume (FEF25-75) (p=0.32), an accepted test of small airways dysfunction.

Conclusion: sGaw tended to decrease before FEV1 in BOS. The trend in sGaw was similar to the trend in FEF25-75. We conclude that (1) small airways may contribute more to airway conductance than previously thought, and (2) further prospective studies are warranted to better define the relative contribution of small and large airways to sGaw.

Chest. 1997;111(6):1536-1541. doi:10.1378/chest.111.6.1536

Study Objective: Increasing evidence indicates that routine preoperative diagnostic spirometry (pulmonary function tests [PFTs]) before elective abdominal surgery does not predict individual risk of postoperative pulmonary complications and is overutilized. This economic evaluation estimates potential savings from reduced use of preoperative PFTs.

Design: Analyses of (1) real costs (resource consumption to perform tests) and (2) reimbursements (expenditures for charges) by third-party payers.

Setting: University-affiliated public and Veterans Affairs hospitals.

Patients: Adults undergoing elective abdominal operations.

Measurements and results: Average real cost of PFTs was $19.07 (95% confidence interval [CI], $18.53 to $19.61), based on a time and motion study. Average reimbursement expenditure by third-party payers for PFTs was $85 (range, $33 to $150; 95% CI, $68 to $103), based on Medicare payment of $52 and a survey of nine urban US hospitals with a spectrum of bed sizes and teaching status. Estimates from published literature included the following: (1) annual number of major abdominal operations, 3.5 million; and (2) proportion of PFTs not meeting current guidelines, 39% (95% CI, 0.31 to 0.47). Local data were used when estimates were not available in the literature: (1) proportion of laparotomies that are elective, 76% (95% CI, 0.73 to 0.79); and (2) frequency of PFTs before laparotomy, 69% (95% CI, 0.54 to 0.84). Estimated annual national real costs for preoperative PFTs are $25 million to $45 million. If use of PFTs were reduced by our estimate for the proportion of PFTs not meeting current guidelines, potential annual national cost savings would be $7,925,411 to $21,406,707. National reimbursement expenditures by third-party payers range from more than $90 million to more than $235 million. If use were reduced, potential annual savings in reimbursements would be $29,084,076 to $111,345,440. Potential savings to Medicare approach $8 million to $20 million annually.

Conclusion: Reduced use of PFTs before elective abdominal surgery could generate substantial savings. Current evidence indicates reduced use would not compromise patients' outcomes.

Chest. 1997;111(6):1542-1547. doi:10.1378/chest.111.6.1542

Study objectives: Scintigraphic prediction of the residual pulmonary function following a lobectomy is not widely employed; its accuracy is poorly known. This study aims at determining the accuracy and the clinical value of the scintigraphic prediction of postlobectomy residual function.

Patients and interventions: In this study, 41 patients with bronchial carcinoma underwent a perfusion lung scintigraphy before lobectomy; the functional contribution of each single lobe was computed by an indirect method proposed by Wernly et al; the results of the scintigraphic prediction were compared with those of the pulmonary function tests performed 1 month after surgery.

Measurements and results: The linear regression analyses of predicted and observed values of FVC and FEV1 showed significant correlations (R2=0.607 and 0.749, respectively); however, an evident scatter of data was obtained, as quantified by the values of imprecision (20.70% and 18.11%, respectively) and global inaccuracy (25.50% and 22.90%, respectively). The estimates of both FVC and FEV1 were significantly better in right lung lobectomies than in left lung lobectomies (mean imprecision and global inaccuracy: 15.43% and 14.94% for the right lung, and 27.27% and 29.00% for the left lung).

Conclusions: The scintigraphic prediction of postlobectomy residual function is easily implemented by the method herein employed; it has a greater margin of uncertainty than that of pneumonectomy, especially for left lobectomies; however, the use of some safety thresholds for predicted values of FEV1 (1.2 L for upper lobectomies and 1 L for lower lobectomies) guarantees a safe clinical use of the test.

Chest. 1997;111(6):1548-1551. doi:10.1378/chest.111.6.1548

Study objectives: To determine the optimal treatment of empyema thoracis (within the fibrinopurulent phase of illness) comparing pleural drainage and fibrinolytic therapy vs video-assisted thoracoscopic surgery (VATS), with regard to efficacy and duration of hospitalization.

Design: Twenty patients with confirmed parapneumonic empyema thoracis were randomized to chest tube pleural drainage plus streptokinase (CT-SK) vs VATS.

Setting: University-based teaching hospital providing for Dallas County.

Patients and methods: Equivalent groups of patients with parapneumonic empyema thoracis were randomized to receive either of two therapies: CT-SK (n=9) or VATS (n=11). Outcomes analysis with respect to treatment efficacy, hospital duration, chest tube duration, hospital costs, and need for subsequent procedures was performed.

Results: Each group suffered one mortality (p=not significant). When compared with the CT-SK group, the VATS group had a significantly higher primary treatment success [10/11, 91% vs 4/9, 44%; p<0.05 Fisher's Exact Test], lower chest tube duration (5.8±1.1 vs 9.8±1.3 days; p=0.03), and lower number of total hospital days (8.7±0.9 vs 12.8±1.1 days; p=0.009). Clinically relevant but not statistically significant differences in hospital costs ($16,642±2,841 vs $24,052±3,466, p=0.11) also favored the VATS group. Of note, all the CT-SK treatment failures could be salvaged with VATS, and none required thoracotomy.

Conclusions: In patients with loculated, complex fibrinopurulent parapneumonic empyema thoracis, a primary treatment strategy of VATS is associated with a higher efficacy, shorter hospital duration, and less cost than a treatment strategy that utilizes catheter-directed fibrinolytic therapy.

Topics: empyema
Chest. 1997;111(6):1552-1559. doi:10.1378/chest.111.6.1552

Study objectives: Description of the development and results of a program in lung volume reduction surgery (LVRS) at a community hospital.

Design: Prospective data collection.

Setting: A 320-bed community hospital.

Patients: Fifty-five patients consecutively discharged from the hospital following LVRS. The mean preoperative FEV1 averaged 28% (±8%) of predicted values, while the preoperative PaCO2 averaged 49 mm Hg (±11.5 mm Hg). Forty-eight patients completed a preoperative conditioning regimen and underwent the procedure on an elective basis. Seven patients underwent the procedure during a hospital admission for a COPD exacerbation. Eight patients required mechanical ventilation preoperatively, including three who had required long-term mechanical ventilatory support.

Results: Three patients (5%) died in the hospital following surgery. One patient developed chronic ventilator dependence. All three of the patients who required long-term mechanical ventilation preoperatively were weaned from the ventilator and returned home. Follow-up pulmonary function testing is available for 42 patients 3 months after surgery, and for 20 patients 6 months after the operation. At 3 months, the mean FEV1 improved 0.19 L (p=0.0002), the mean improvement for FVC was 0.37 L (p=0.0001), and the mean drop in residual volume was 0.97 L (p=0.0001). Similar changes are seen at 6 months. Highly significant improvements were also seen in quality of life measurements and exercise performance. The benefits of surgical treatment of emphysema seemed similar in both elective and urgent groups.

Conclusions: LVRS can be done safely and effectively at a community hospital, with significant improvement in pulmonary function and quality of life.

Chest. 1997;111(6):1560-1564. doi:10.1378/chest.111.6.1560

Objective: This study was designed (1) to investigate the effects of normothermic and hypothermic perfusion on the median frequency of the fibrillating myocardium, and (2) to elucidate whether frequency-guided countershock therapy improves countershock success during the reperfusion phase of cardiac surgery.

Design: Prospective, randomized study.

Setting: University hospital cardiac surgery room.

Patients: Thirty patients (first part of the study) and 38 patients (second part of the study) scheduled for elective coronary artery bypass surgery.

Methods and results: During cardiopulmonary bypass, ventricular fibrillation (VF) was induced at a core body temperature of 34.1±0.2°C (normothermia) (n=15) or at a core body temperature of 29.8±0.2°C (hypothermia) (n=15). Using fast Fourier transformation of the ECG signal, median fibrillation frequency was recorded continuously for a period of 120 s. At the end of surgery, countershock was performed as soon as VF was recognized on the ECG monitor (X Hz group; n=19) or countershock was not performed until median fibrillation frequency had increased to the threshold of at least 5 Hz (5 Hz group; n=19). Median fibrillation frequency in the normothermic fibrillation group was statistically higher than in the hypothermic group. In the X Hz and 5 Hz countershock group, median fibrillation frequency before the first countershock attempt was 3.6±0.2 Hz and 5.4±0.1 Hz (p<0.0001), respectively. In the X Hz group, six countershocks resulted in supraventricular rhythm, 10 in VF, two in electromechanical dissociation, and one in asystole. In the 5 Hz group, 16 countershocks resulted in supraventricular rhythm, two in VF, and one in asystole (p=0.008).

Conclusions: During normothermia, median fibrillation frequency is significantly higher than during hypothermic perfusion conditions. During the reperfusion phase of cardiac surgery, countershock success rate is significantly higher when a threshold of at least 5 Hz had been reached before the first countershock attempt.

Chest. 1997;111(6):1565-1570. doi:10.1378/chest.111.6.1565

We assessed the clinical efficacy and determined the effective dose of erythropoietin (EPO) in 48 children scheduled for open heart surgery without blood transfusion. The children were divided into three groups: group 1 (n=21) was treated with 300 U/kg of EPO; group 2 (n=11) was treated with 150 U/kg of EPO; and group 3 (n=16) was not treated with EPO. EPO was administered on the day of hospital admission (6 to 7 days prior to surgery), on the following day, immediately after surgery, and on the following day. Immediately after surgery, the hemoglobin concentration in groups 1 and 2 was significantly higher than that in group 3. The reticulocyte count in groups 1 and 2 was significantly higher than that in group 3. Open heart surgery was completed without transfusion in all 21 patients in group 1 (100%), 10 of 11 in group 2 (90.9%), and 11 of 16 in group 3 (68.8%). EPO caused no adverse reactions. In conclusion, EPO was effective as an adjuvant therapy for open heart surgery without blood transfusion in children. Administration of a relatively high dose of EPO (300 U/kg) seems to be effective for pediatric patients.

Chest. 1997;111(6):1571-1576. doi:10.1378/chest.111.6.1571

The purpose of this study was to investigate the possible use of integrated surface electromyography (iEMG) in cardiac transplant patients (CTPs) as a new noninvasive determinant of the metabolic response to exercise by studying the relationship between the iEMG threshold (iEMGT) and other more conventional methods for anaerobic threshold (AT) determination, such as the lactate threshold (LT) and the ventilatory threshold (VT). Thirteen patients (age: 57±7 years, mean±SD; height: 163±7 cm; body mass: 70.5±8.6 kg; posttransplant time: 87±49 weeks) were selected as subjects. Each of them performed a ramp protocol on a cycle ergometer (starting at 0 W, the workload was increased in 10 W/min). During the tests, gas exchange data, blood lactate levels, and iEMG of the vastus lateralis were collected to determine VT, LT, and iEMGT, respectively. The results evidenced no significant difference between mean values of VT, LT, or iEMGT, when expressed either as oxygen uptake (11.1±2.4, 11.7±2.3, and 11.0±2.8 mL/kg/min, respectively) or as percent maximum oxygen uptake (61.6±7.5, 62.2±7.7, and 59.6±8.2%, respectively). In conclusion, our findings suggest that iEMG might be used as a complementary, noninvasive method for AT determination in CTPs. In addition, since the aerobic impairment of these patients is largely due to peripheral limitation, determination of iEMGT could be used to assess the effectiveness of an exercise rehabilitation program to improve muscle aerobic capacity in CTPs.

Chest. 1997;111(6):1577-1582. doi:10.1378/chest.111.6.1577

Objective: To evaluate the onset of exercise-induced interstitial pulmonary edema in cardiac patients by high-resolution CT (HRCT).

Design: Prospective, normal controlled.

Participants: Thirty subjects divided into three groups: group 1—10 outpatients with chronic congestive heart failure (CCHF), New York Heart Association (NYHA) class I; group 2—10 outpatients with CCHF, NYHA class II/III; and group 3 (control)—10 normal subjects.

Method: HRCT scans were obtained at rest and 4, 8, 12, 16, and 20 min after progressive treadmill exercise test.

Results: The following HRCT findings consistent with interstitial edema were significantly different (p<0.05) in group 2 when compared with groups 1 and 3: artery/bronchus ratio >1 in the upper lobes, peripheral increase in the vascular markings, interlobular septal thickening, and peribronchial "cuffing." These differences were maximal at 12 min after exercise and returned to normal values after 20 min.

Conclusion: Interstitial pulmonary edema was present immediately after exercise in CCHF patients. It may be important in the genesis of dyspnea of these patients.

Chest. 1997;111(6):1583-1590. doi:10.1378/chest.111.6.1583

Study objectives: To assess the health and cost effects of a patient's risk-taking attitudes about diagnostic tests.

Design: Cost-effectiveness analysis.

Setting: Diagnostic testing strategies used in the evaluation of a patient with a radiographically detected lung lesion were evaluated. Strategies included combinations of sputum, fine-needle aspiration, bronchoscopy, thoracoscopy, and expectant management.

Patients: Patient data were obtained from the Survival Epidemiology and End Results Program, MEDLINE search, National Center for Health Statistics, and the Universities of Iowa and Stanford, and Kaiser Permanente Hospital.

Interventions: Different patient risk-taking attitudes were simulated using decision analysis.

Measurements: Lifetime cost of medical care, life expectancy, and cost effectiveness.

Results: The cost effectiveness of competing strategies depended on patient attitudes about taking risks. For a patient averse to expectantly waiting without definitive knowledge of whether cancer was or was not present, testing strategies using invasive procedures, such as thoracoscopy, were more cost effective. In contrast, for a patient who was identical except that he or she was averse to tests with higher morbidity and mortality, strategies that involved expectantly waiting, instead of more invasive tests, were more cost effective. Small changes in some risk-taking attitudes resulted in large changes in cost effectiveness.

Conclusions: Risk-taking attitudes influenced the cost effectiveness of testing strategies. Consideration of patient risk-taking attitudes in diagnostic testing appears warranted in setting clinical policies and making individual decisions.

Chest. 1997;111(6):1591-1596. doi:10.1378/chest.111.6.1591

Objective: Pulmonary cytologic specimens reported as "suspicious for malignancy" pose problems in clinical management. Silver staining for argyrophilic nucleolar organizer regions (AgNOR) has proved useful in making a cytopathologically differential diagnosis between benign and malignant cells. This study aimed to evaluate the usefulness of AgNOR score in the diagnosis of pulmonary cytologic specimens deemed inconclusive by conventional staining methods.

Methods: Pulmonary cytologic specimens initially reported as suspicious for malignancy with Papanicolaou or May-Grünwald-Giemsa (MGG) staining obtained from 35 proved cases were destained then restained using the AgNOR technique. Another 35 cases with clear cytologic diagnosis were also examined for comparison. The median number of dots, defined as the AgNOR score, was used to differentiate malignant from benign specimens.

Results: Malignant cases had significantly higher AgNOR scores than benign ones (p<0.001). There were no significant differences among smears previously stained with Papanicolaou or MGG method, among specimens obtained via bronchoscopic brushing, fine-needle aspiration of lung or pleural effusion, or among subgroups of malignant diseases. Based on the results of our previous study, the cutoff value of the AgNOR score to differentiate benignancy from malignancy was set at 6. At this setting, the sensitivity and specificity of AgNOR score were 88% and 80%, respectively, in aiding a differential diagnosis of pulmonary cytologic specimens initially classified as suspicious for malignancy. For those cases with a clear cytologic diagnosis, the sensitivity and specificity of AgNOR score were 92% and 100%, respectively. For all cases, the sensitivity of AgNOR score was 90% and the specificity was also 90%.

Conclusions: The AgNOR score is of value in aiding a differential diagnosis between benign and malignant lesions in pulmonary specimens with equivocal cytologic features.

Chest. 1997;111(6):1597-1599. doi:10.1378/chest.111.6.1597

Twenty-one patients with malignant pleural effusion (MPE) were prospectively entered into a nonrandomized, single-armed study to evaluate the efficacy and safety of recombinant interferon (IFN) alpha-2b (INTRON A; Schering-Plough; Kenilworth, NJ) as an intrapleural palliative agent. From March 1989 through February 1993 (48 months), 21 patients were entered into the study. No symptomatic effusion recurred and no substantial side effects were associated with treatment. This suggests recombinant IFN alpha-2b represents a safe and effective intrapleural agent for the palliation of MPE.

Chest. 1997;111(6):1600-1602. doi:10.1378/chest.111.6.1600

Study objectives: To determine whether bone imaging with 99mTc methylene diphosphonate is a specific method of making the diagnosis of costochondritis in patients with chest pain who rule out for myocardial infarction.

Design: Nonblinded prospective controlled study in 20 patients and 10 control subjects.

Setting: Inpatient medical service of a tertiary teaching hospital.

Patients: Two hundred consenting patients admitted to the hospital with chest pain and suspected myocardial infarction were examined. Those in whom acute myocardial infarction was ruled out were evaluated for the clinical signs of costochondritis, ie, tenderness over one or more costochondral junctions. Twenty patients who met the clinical criterion gave informed consent and were subjected to bone imaging. Ten control subjects with cancer who did not have clinical signs of costochondritis underwent bone imaging to rule out metastatic disease (normal in all cases).

Interventions: Bone imaging with IV 99mTc methylene diphosphonate.

Measurements: Bone scans of the investigative patients and the control subjects were read by two independent nuclear medicine specialists.

Results: Sixteen of the 20 patients with clinically diagnosed costochondritis showed increased technetium uptake at all costochondral junctions bilaterally; six of them also had increased uptake elsewhere on the chest wall (sternum, manubrium, or first rib). All 10 of the control patients likewise showed increased technetium uptake at all costochondral junctions bilaterally.

Conclusions: Bone imaging with 99mTc methylene diphosphonate is not a specific method of making the diagnosis of costochondritis.

Chest. 1997;111(6):1603-1606. doi:10.1378/chest.111.6.1603

Background: Recent findings have demonstrated a high frequency of activated protein C resistance in patients suffering from deep venous thrombosis (DVT). This abnormality has been related to a mutation in the factor V gene (at nucleotide position 1,691, guanine to adenine [G→A] substitution).

Aim: To assess the frequency of the mutation in unselected inpatients with a proved DVT. To study the clinical characteristics of such patients.

Methods: All consecutive patients admitted to the hospital because of a clinical suspicion of DVT were eligible. Diagnosis of DVT with the help of venous ultrasound imaging or venography. Ventilation and perfusion lung scan was performed in all patients, and interpreted according to the Prospective Investigation of Pulmonary Embolism Diagnosis criteria; in patients with a lowor intermediate-probability lung scan, pulmonary angiography was requested. Polymerase chain reaction amplification was performed in patients with a proved DVT. A control group consisted of bone marrow volunteer donors.

Results: From July 1994 to November 1995, 165 patients were included. Thrombosis was considered as distal in 77 and proximal in 88; an associated pulmonary embolism (PE) was found in 75 patients. Of 165 patients, 24 (14.5%) showed the factor V gene mutation (95% confidence interval, 9.4 to 19.8); the mutation was present in 3.5% of 200 bone marrow volunteer donors; odds ratio for having DVT in the presence of the mutation was 4.1. No difference in the level of DVT, or the presence of an associated PE was observed according to the presence of the mutation. Patients with the mutation have a significantly more frequent history of DVT (p=0.04) and more previous reported episodes (1.1 vs 0.6; p=0.04).

Conclusion: The factor V mutation is frequent in unselected DVT patients. No difference in the severity of the thrombosis episode was observed in these patients.

Chest. 1997;111(6):1607-1614. doi:10.1378/chest.111.6.1607

Study objectives: We developed a symptom-based measure of severity for chronic lung disease (CLD) that can be readily administered in ambulatory care settings and be used to supplement general health-related quality of life (HRQoL) assessments and pathophysiologic indicators in research and clinical care.

Design: Cross-sectional data from the Veterans Health Study, an observational study of health outcomes in patients receiving Veterans Affairs (VA) ambulatory care.

Setting: Four VA outpatient clinics.

Study subjects: Two hundred ninety-two participants with CLD were identified on the basis of patient report of having a physician's diagnosis of chronic bronchitis, emphysema, or asthma and either using inhaled medications or having a productive cough on most days for 3 months.

Measurements and results: Participants were scheduled for an in-person interview in which they completed a CLD questionnaire and measurements of peak expiratory flow rate (PEFR). They were also mailed an HRQoL questionnaire, the Short Form Health Survey (SF-36). The CLD questionnaire included six symptom items chosen by an expert panel (two items each for dyspnea, wheezing, and productive cough). The combination of these items yielded a CLD severity index that correlated significantly with all eight scales of the SF-36 (range of r, −0.19 to −0.37; p<0.01). In contrast, PEFR had statistically significant correlations only with two SF-36 scales: physical functioning and bodily pain.

Conclusions: The CLD severity index is a reliable and valid patient-administered instrument that may be used to evaluate the effects of CLD on general HRQoL and predict future health services utilization.

Chest. 1997;111(6):1615-1621. doi:10.1378/chest.111.6.1615

The approach to the diagnosis and management of patients with diffuse infiltrative lung disease (DILD) is controversial. The results of transbronchial biopsy are often unsatisfactory. The role of open lung biopsy is highly variable. Percutaneous cutting needle biopsy (CNB) is not recommended because of its reported high morbidity/mortality relative to its low diagnostic yield. We report a technique for CNB with a high diagnostic yield and a low morbidity and no mortality in 228 patients with DILD over the past 23 years.

Methods: The salient features of the technique for CNB are as follows: the anesthetic needle does not enter the pleural space; a Franklin Silverman needle is inserted into the intercostal space posteriorly at outer one-third of chest wall; the biopsy is performed with the breath held at normal end expiration; the plane of pleural space is broken with sudden insertion of needle 8 to 15 cm into lung; and the pathway of the needle is maintained parallel to the lateral chest wall.

Results: A diagnosis was established in 129 of 145 biopsies (89%) performed by a trained operator (A.H.N.). There were 36 pneumothoraces (25%), four minimal hemoptyses (3%), and two chest tube placements (1%). There were no deaths (0%).

Conclusion: With meticulous attention to technique and careful selection of patients, the procedure offers a relatively safe alternative to open lung or thoracoscopic lung biopsy in patients with DILD.

Chest. 1997;111(6):1622-1630. doi:10.1378/chest.111.6.1622

Study objectives and patients: Pulmonary hypertension (PH) is common in COPD and may predict mortality in this disorder. We have compared the pulmonary vasodilator effects, dose-response characteristics, and tolerability of two calcium channel blockers, amlodipine and extended-release (ER) felodipine, in 10 patients (seven men, age 68±4.8 [SD] years) with clinically stable COPD and PH.

Design: Drugs were given in equal single daily oral doses (2.5, 5, and 10 mg), increasing weekly for 3 weeks, in a randomized investigator-blinded crossover manner with a 1-week wash-out period between the two treatments.

Measurements: Doppler measurements of pulmonary hemodynamics were made on the seventh day of treatment at each drug dose. Lung function, arterial blood gases, and adverse events were also monitored weekly.

Results: A dose-dependent decline of pulmonary artery pressure (PAP) was observed with each drug. A dose of 2.5 mg produced a significant decrease in PAP compared with baseline (20% amlodipine, 17% felodipine ER). Additional decreases in PAP were observed at 5 mg and 10 mg that were similar for both drugs, but did not reach statistical significance compared with 2.5 mg. There was a dose-related decrease in pulmonary vascular resistance and increase in oxygen delivery with amlodipine and felodipine ER. Lung function and blood gas values were stable throughout. Side effects (headache and ankle edema) were less frequent during amlodipine treatment (p<0.05).

Conclusions: Both amlodipine and felodipine ER, given as a single daily oral dose of ≥2.5 mg, are effective pulmonary vasodilators in COPD patients with PH. Their dose-response characteristics are similar, but amlodipine treatment was associated with fewer side effects.

Chest. 1997;111(6):1631-1638. doi:10.1378/chest.111.6.1631

Study objectives: It has been suggested that noninvasive mechanical ventilation (NIMV) may be a time-consuming procedure for medical and paramedical personnel. We carried out a prospective trial in 10 consecutive COPD patients aimed at assessing the human and economic resources needed to ventilate patients by NIMV and we compared these with those needed by a group of six patients receiving invasive mechanical ventilation (InMV).

Design: The daily cost and the minutes spent by medical doctors (MDs), respiratory therapists (RTs), and nurses (Ns) were recorded during the first 48 h of ventilation in 10 patients during NIMV (group A) and in six who received InMV (group B) after an initial unsuccessful attempt with NIMV. In two subgroups of patients (five for group A and four for group B), the analysis was also performed, except for RTs, for the total length of mechanical ventilation.

Setting: A respiratory ICU.

Patients: At hospital admission, the two groups of COPD patients did not differ for blood gas values (PaCO2=88.2±9.8 mm Hg for group A vs 90.5±12.8 mm Hg for group B, and pH=7.21+0.08 vs 7.20+0.08, respectively) or for clinical and neurologic status, but patients of group B had not tolerated NIMV.

Measurements and results: The total time spent at the bedside in the first 6 h did not differ between group A and B (group A=72.3 min [MD], 87.2 min [RT], and 178.8 min [N] vs 98.8 min [MD], 12.5 min [RT], and 197.6 min [N] for group B). In the following 42 h, a plateau was reached so that there was a significant reduction for both groups in the time of assistance given by Ns (p<0.001) but not by MDs or RTs. The total costs were also not different between the two groups ($806±73 [US dollars per day] vs $864±44 for group A and B, respectively). In the subgroups monitored for the entire period of ventilation, a significant reduction in the time of assistance, for both MDs and Ns, was observed after approximately the first half.

Conclusions: We conclude that in the first 48 h of ventilation, daily NIMV is neither more expensive nor time-consuming and staff demanding than InMV. After the first few days of ventilation, NIMV was significantly less time-consuming than InMV, for MDs and Ns, so that medical and paramedical time expenditure seems not to be a major problem during NIMV.

Chest. 1997;111(6):1639-1648. doi:10.1378/chest.111.6.1639

Study objective: To compare the effects of noninvasive assist-control ventilation (ACV) and pressure support ventilation (PSV) by nasal mask on respiratory physiologic parameters and comfort in acute hypercapnic respiratory failure (AHRF).

Design: A prospective randomized study.

Setting: A medical ICU.

Patients and interventions: Fifteen patients with COPD and AHRF were consecutively and randomly assigned to two noninvasive ventilation (NIV) sequences with ACV and PSV mode, spontaneous breathing (SB) via nasal mask being used as control. ACV and PSV settings were always subsequently adjusted according to patient's tolerance and air leaks. Fraction of inspired oxygen did not change between the sequences.

Measurements and results: ACV and PSV mode strongly decreased the inspiratory effort in comparison with SB. The total inspiratory work of breathing (WOBinsp) expressed as WOBinsp/tidal volume (VT) and WOBinsp/respiratory rate (RR), the pressure time product (PTP), and esophageal pressure variations (ΔPes) were the most discriminant parameters (p<0.001). ACV most reduced WOBinsp/VT (p<0.05), ΔPes (p<0.05), and PTP (0.01) compared with PSV mode. The surface diaphragmatic electromyogram activity was also decreased >32% as compared with control values (p<0.01), with no difference between the two modes. Simultaneously, NIV significantly improved breathing pattern (p<0.01) with no difference between ACV and PSV for VT, RR, minute ventilation, and total cycle duration. As compared to SB, respiratory acidosis was similarly improved by both modes. The respiratory comfort assessed by visual analog scale was less with ACV (57.23±30.12 mm) than with SB (75.15±18.25 mm) (p<0.05) and PSV mode (81.62±25.2 mm) (p<0.01) in our patients.

Conclusions: During NIV for AHRF using settings adapted to patient's clinical tolerance and mask air leaks, both ACV and PSV mode provide respiratory muscle rest and similarly improve breathing pattern and gas exchange. However, these physiologic effects are achieved with a lower inspiratory workload but at the expense of a higher respiratory discomfort with ACV than with PSV mode.

Chest. 1997;111(6):1649-1653. doi:10.1378/chest.111.6.1649

Background: Adult mechanical ventilators have traditionally been pressure- or time-triggered. More recently, flow triggering has become available and some adult ventilators allow the choice between pressure or flow triggering. Prior studies have supported the superiority of flow triggering during continuous positive airway pressure, but few have compared pressure and flow triggering during pressure support ventilation (PSV). The purpose of this study was to compare pressure and flow triggering during PSV in adult mechanically ventilated patients.

Methods: The study population consisted of 10 adult patients ventilated with a mechanical ventilator (Nellcor-Puritan-Bennett 7200ae) in the PSV mode. In random order, we compared pressure triggering of −0.5 H2O, pressure triggering −1 cm H2O, flow triggering of 5/2 L/min, and flow triggering 10/3 L/min. Pressure was measured for 5 min at the proximal endotracheal tube using a data acquisition rate of 100 Hz. From the airway pressure signal, trigger pressure (ΔP) was defined as the difference between positive end-expiratory pressure (PEEP) and the maximum negative deflection prior to onset of the triggered breath. Pressure-time product (PTP) was defined as the area produced by the pressure waveform below PEEP during onset of the triggered breath. Trigger time (ΔT) was defined as the time interval below PEEP during onset of the triggered breath.

Results: A pressure trigger of −0.5 cm H2O was significantly more sensitive than the other trigger methods for ΔP, PTP, and ΔT (p<0.001). There was also a significant difference between patients for ΔP, ΔT, and PTP for each trigger method (p<0.001).

Conclusions: For this group of patients, flow triggering was not superior to pressure triggering at −0.5 cm H2O during PSV.

Chest. 1997;111(6):1654-1659. doi:10.1378/chest.111.6.1654

Study objectives: To update our database, reporting changes in the results of weaning attempts and profile of patients transferred to us after prolonged mechanical ventilation (PMV) in the ICU.

Design: Retrospective record review, with prospective recording of physiologic measurements on admission from mid-1994.

Setting: Regional weaning center (RWC).

Patients: We studied 1,123 consecutive ventilator-dependent patients transferred for attempted weaning over an 8-year period.

Measurements and results: Median (range) time of mechanical ventilation prior to transfer to the RWC declined from 37 (1 to 249) days in 1988 to 29 (1 to 120) days in 1996 (p<0.05). Acute physiology score of acute physiology and chronic health evaluation (APACHE) III was 32 (6 to 123) on RWC admission, equaling reported scores soon after ICU admission. Comparing other data on admission from 1988 to 1996, mean (±SD) serum albumin level declined from 2.92±0.58 to 2.43±0.50 g/dL, and alveolar-arterial oxygen pressure difference widened from 106±50 to 139±99 mm Hg. Prevalence of stage II or worse pressure ulceration on admission increased from 34% in 1988 to 46% in 1995. Despite these trends, there has been no significant change in patient outcome (55.9% weaned, 15.6% failed to wean, 28.8% died) or in median time to wean (29 [1 to 226] days). Overall survival at 1 year after discharge for the 8-year period is 37.9%, improving from 29% in 1988-1991 to 45% since 1992; survival in weaned patients discharged to home has improved from 45 to 59% during the respective time periods.

Conclusions: Patients are being transferred from the ICU to our RWC for attempted weaning sooner in their course of PMV. Although more severely ill on arrival than in past years, mortality is unchanged, more than half of the patients continue to be successfully weaned, and survival after RWC discharge is improved.

Chest. 1997;111(6):1660-1665. doi:10.1378/chest.111.6.1660

Study objective: To determine the usefulness of routinely inserting a hollow airway exchange catheter (jet stylet) prior to tracheal extubation of adult patients with risk factors for difficult tracheal intubation.

Design: Prospective, 1-year study of 40 consecutive patients undergoing mechanical ventilation who had one or more risk factors for difficult tracheal reintubation.

Setting: Surgical ICU of a tertiary university medical center.

Interventions: Study patients at risk for difficult tracheal reintubation were extubated using a No. 11 Cook airway exchange catheter (CAEC). Following tracheal extubation, the CAEC was secured, and humidified oxygen was insufflated through the central lumen (2 to 8 L/min) for a minimum of 4 h, during which oxyhemoglobin saturation (SpO2) and respiratory frequency were monitored. Stridor or other signs of respiratory difficulty were also assessed. The CAEC was removed when it became clinically apparent that the need for tracheal reintubation was unlikely. When patients failed to respond to tracheal extubation, the CAEC was used to facilitate reintubation of these difficult airways.

Results: Respiratory distress necessitating tracheal reintubation occurred in 3 of 40 patients (8%). One patient failed to respond to tracheal extubation twice. None of the patients developed oxyhemoglobin desaturation (SpO2 <90%) before or during tracheal reintubation. All four reintubations were accomplished during the first attempt using the CAEC as a stylet. The CAEC was kept in the trachea for a mean duration of 9.4 h. There were no adverse events documented.

Conclusions: The No. 11 CAEC is a useful and effective tool for giving patients a trial of extubation. Administration of oxygen through the CAEC diminishes the potential for hypoxia while maintaining the ability to reintubate the trachea, especially when reintubation might prove challenging. Previous data suggest that the CAEC is rigid enough to facilitate tracheal reintubation in adults; this was confirmed in the three patients in our study who required tracheal reintubation. The risk of aspiration, barotrauma, or other airway trauma during prolonged placement of the CAEC appears to be low (zero incidence in 40 patients in this study), and use of the No. 11 CAEC appeared to be safe. Since oxygen can be delivered through the CAEC, it may provide a means to safely evaluate an airway during a trial of extubation, ie, a reversible extubation. Finally, oxygen administration through the CAEC may obviate the need for facemask or nasal cannula following tracheal extubation.

Chest. 1997;111(6):1666-1671. doi:10.1378/chest.111.6.1666

Study objective: To assess the prognostic performance of general severity systems (APACHE II [acute physiology and chronic health evaluation], simplified acute physiology score [SAPS II], and mortality probability models [MPM II]) in coronary patients and to derive new customized indexes for coronary patients using a reduced number of variables.

Design: Inception cohort.

Setting: Adult medical and surgical ICUs in 17 hospitals in Catalonia and the Balearic Islands.

Patients: Four hundred fifty-six patients with acute myocardial infarction.

Measurements and results: The APACHE II, SAPS II, and MPM II variables and survival status at hospital discharge have been collected. Performance of the severity systems was assessed by evaluating calibration and discrimination. Logistic regression was used to customize the MPM II24 and SAPS II indexes. Discrimination was high enough for all of the models. However, calibration of the MPM II24 was not as satisfactory as for the other models. The MPM II24 and SAPS II were both reduced to five variables (MPM II24 cor: age, PaO2, continuous vasoactive drugs, urinary output, and mechanical ventilation; SAPS IIcor: age, PaO2/FIo2 ratio, systolic BP, Glasgow coma score, and urinary output). Both models showed better calibration and discrimination than the original ones.

Conclusions: Prognostic indexes developed for multidisciplinary patients show good performance when applied to patients with acute myocardial infarction, but customization can reduce the number of variables necessary to compute them without a loss of, and a possible improvement in, prognostic accuracy.

Chest. 1997;111(6):1672-1678. doi:10.1378/chest.111.6.1672
Chest. 1997;111(6):1679-1683. doi:10.1378/chest.111.6.1679

Study objectives: The objective of this study was to determine the impact of the timing of chest tube insertion on outcome for the treatment of empyema, using a new animal model of empyema.

Design: A prospective, controlled randomized, blinded design was used.

Setting: The study was conducted in an animal research laboratory.

Patients or participants: Sixty-six 2- to 3-kg rabbits were used in this study.

Interventions: After induction of empyema, the rabbits were divided into four groups. Fourteen rabbits had chest tubes placed at 24 h after empyema induction. Seventeen rabbits had chest tubes placed at 48 h and 14 rabbits had chest tubes placed at 72 h after empyema induction. Twenty-one rabbits served as control rabbits and had no chest tubes placed.

Measurements and results: Ten days after induction of empyema, the rabbits were killed. The pleural spaces of each rabbit were examined and a gross score, pleural peel score, and a microscopic score were calculated for each rabbit. The median gross score, mean pleural peel score, and median microscopic scores were significantly higher in the rabbits that underwent late chest tube placement (72 h) relative to those that underwent early chest tube placement (24 or 48 h).

Conclusions: This study supports previous expert opinion statements and conclusions from retrospective analyses that early chest tube placement (relative to delayed chest tube placement) is beneficial for the treatment of empyema.

Topics: empyema , chest tubes
Chest. 1997;111(6):1684-1690. doi:10.1378/chest.111.6.1684

Background: Mouse/human chimeric antibody Z2D3 identifies an antigen produced exclusively by proliferating smooth muscle cells of human atheroma, and also cross reacts with experimentally induced atherosclerotic lesions in rabbits. Fab' fragments of Z2D3 antibody were labeled with 99mTc using glucaric acid as a weak transchelator. The potential role of 99mTc-labeled Z2D3 scintigraphy was explored for noninvasive imaging of experimental atherosclerotic lesions.

Methods and results:99mTc-Z2D3 Fab' was utilized for noninvasive imaging in four rabbits with experimentally induced atherosclerotic lesions and in one control rabbit. In addition, 99mTc-labeled nonspecific 103D2 Fab' was used for comparison in four other rabbits with atherosclerotic lesions. The atherosclerotic lesions were induced by balloon de-endothelialization of the infradiaphragmatic abdominal aorta and 12 weeks of hyperlipidemic diet. An aliquot of 15 mCi (550 mBq) of 99mTc pertechnetate was incubated with 6.25 mg of glucaric acid for 30 min followed by incubation of 99mTc glucarate with 375 µg of Z2D3 Fab' or 103D2 Fab' for an additional 30 min. Instant thin-layer chromatography demonstrated almost complete radiolabeling. 99mTc-Z2D3 was administered IV and gamma imaging was performed at the time of injection, 3, 6, 9, and 12 h, followed by ex vivo imaging of the excised aorta, and biodistribution was performed. Unequivocal visualization of atherosclerotic lesions was possible in all four animals at 9 to 12 h with Z2D3 Fab'. Quantitative uptake, as represented by mean lesion-to-liver count density ratio, was 0.6±0.05. Imaging with nonspecific 103D2 Fab' did not show any localization in the abdominal aorta (lesion-to-liver ratio, 0.45±0.02, p=0.02). Ex vivo lesion-to-normal aortic segment ratio was 4.3±0.9 for Z2D3 and 1.04±0.08 for nonspecific 103D2 Fab' (p=0.01). Biodistribution studies demonstrated 0.03±0.003% injected Z2D3 dose per gram in the atherosclerotic lesions as compared with 0.01±0.003% in the nondenuded thoracic aorta of atherosclerotic rabbits (p=0.008). However, only 0.008±0.002% of the mean injected dose per gram was obtained in the atherosclerotic lesions (p=0.001) as compared with 0.005±0.003% in the normal aortic segments with 103D2. No Z2D3 uptake in normal rabbits was observed on either the in vivo or ex vivo images.

Conclusions: The present study demonstrates that 99mTc-based immunoimaging of the vascular lesions may be feasible by the use of smaller antibody fragments. Earlier visualization is possible at the expense of a lower absolute antibody uptake in the lesions as compared to the use of intact antibody or larger fragments with longer circulating time.

Topics: muscle, smooth
Chest. 1997;111(6):1691-1696. doi:10.1378/chest.111.6.1691

Background: Development and progression of human malignancies involve multiple genetic changes. New techniques to distinguish neoplastic from benign diseases unequivocally with small amounts of cells as gained by bronchoscopy are needed to come closer to the goal of an early diagnosis in lung cancer.

Study objective: The aim of this study was to determine whether interphase fluorescence in situ hybridization (FISH) can be used to visualize chromosomal aberrations in bronchoscopically gained cells from lung cancer patients and could eventually become a complementary technique to conventional cytology.

Methods: We examined 20 cancerous specimens (10 primary tumors, 10 malignant effusions) of 18 lung cancer patients by FISH with DNA probes specific for chromosomes 3, 8, 11, 12, 17, and 18. From five additional patients, endobronchial brushings and/or forceps biopsy specimens were subjected to interphase FISH analysis.

Results: In all primary tumors and malignant effusions, highly aneuploid cells were detectable by FISH. Chromosomal aberrations always consisted of gains of chromosomal signal numbers, and all chromosomes were found to be aneuploid to a similar extent. Using chromosomal aneuploidy as a marker of malignancy, material obtained by bronchoscopy was then examined for the presence of malignant cells. In all specimens, evidence for malignancy was obtained by FISH, including three specimens in which cells appeared to be normal or reactively changed by cytologic criteria.

Conclusion: We conclude that interphase FISH is useful in detecting aneuploidy associated with malignancy in bronchoscopically gained cells that do not clearly meet the criteria of malignancy by conventional cytologic study.

Chest. 1997;111(6):1697-1701. doi:10.1378/chest.111.6.1697

Gamma-delta (γ/δ) T cells are thought to represent the first line of defense against various pathogenic microorganisms. The aim of the present study was to investigate whether γ/δ T cells were increased in BAL fluid (BALF) of patients with diffuse panbronchiolitis (DPB), a model of chronic lower respiratory tract infection. The study population consisted of four groups, including patients with DPB, sarcoidosis, idiopathic pulmonary fibrosis, and normal subjects. Two-color direct immunofluorescence and flow cytometry were used for analysis of peripheral blood or BALF from these patients. The percentage of peripheral blood or BALF γ/δ T cells relative to the total number of lymphocytes was similar in the four groups. Although the absolute number of γ/δ T cells in BALF was significantly higher in DPB patients compared with the other three groups, the total lymphocyte number in BALF in DPB patients was increased and the number of BALF γ/δ T cells correlated with the total lymphocyte number in BALF. Furthermore, the percentage and number of BALF γ/δ T cells were not related to a certain group of pathogenic organisms or the number of colony-forming units. Our results suggest that γ/δ T cells are unlikely to play a part in chronic lower respiratory tract infection.

Chest. 1997;111(6):1710-1717. doi:10.1378/chest.111.6.1710

Revisions in stage grouping of the TNM subsets (T=primary tumor, N=regional lymph nodes, M=distant metastasis) in the International System for Staging Lung Cancer have been adopted by the American Joint Committee on Cancer and the Union Internationale Contre le Cancer. These revisions were made to provide greater specificity for identifying patient groups with similar prognoses and treatment options with the least disruption of the present classification: T1N0M0, stage IA; T2N0M0, stage IB; T1N1M0, stage IIA; T2N1M0 and T3N0M0, stage IIB; and T3N1M0, T1N2M0, T2N2M0, T3N2M0, stage IIIA. The TNM subsets in stage IIIB—T4 any N M0, any T N3M0, and in stage IV—any T any N M1, remain the same. Analysis of a collected database representing all clinical, surgical-pathologic, and follow-up information for 5,319 patients treated for primary lung cancer confirmed the validity of the TNM and stage grouping classification schema.

Topics: lung cancer
Chest. 1997;111(6):1718-1723. doi:10.1378/chest.111.6.1718

Recommendations for classifying regional lymph node stations for lung cancer staging have been adopted by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer. The objective was to unify the two systems that have been in common use for the past 10 years; that is, the schema advocated by the AJCC, adapted from the work of Tsuguo Naruke, and the schema advocated by the American Thoracic Society and the North American Lung Cancer Study Group. Anatomic landmarks for 14 hilar, intrapulmonary, and mediastinal lymph node stations are designated. This classification provides for consistent, reproducible, lymph node mapping that is compatible with the international staging system for lung cancer. It is applicable for clinical and surgical-pathologic staging.

Chest. 1997;111(6):1724-1732. doi:10.1378/chest.111.6.1724
Chest. 1997;111(6):1733-1741. doi:10.1378/chest.111.6.1733

We conducted a longitudinal study to determine the annual rate decline in pulmonary function measurements in male swine confinement workers. For comparison, a grain farming group and a nonfarming rural-dwelling control group were also chosen for the longitudinal study. Two hundred seventeen swine confinement workers, 218 grain farmers, and 179 nonfarming control subjects had valid pulmonary function measurements at the baseline observation conducted in 1990 to 1991 and at the second observation conducted in 1994 to 1995. The swine confinement workers were younger (mean age=38.3±11.7 [SD] years) than the nonfarming control subjects (42.6±10.4 years) and the grain farmers (44.5±11.9 years). When stratified by age, nonfarming control subjects had the lowest mean annual rate decline in FEV1 and FVC in all age categories. The swine confinement workers had the largest annual rate decline in FEV1 and FVC, and this was most obvious in the middle age categories. After controlling for age, height, smoking, and baseline pulmonary function, swine confinement workers had excess annual decline of 26.1 mL in FEV1 (p=0.0005), 33.5 mL in FVC (p=0.0002), and 42.0 mL/s in forced expiratory flow between 25% and 75% of FVC (FEF25-75%) (p=0.02) over nonfarming control subjects. Grain farmers had excess annual decline of 16.4 mL in FEV1 (p=0.03), 26.7 mL in FVC (p=0.002), and 11.2 mL/s in FEF25-75% (p=0.38) over control subjects. These findings suggest that workers engaged in the swine industry and grain farmers appear prone to accelerated yearly losses in lung function and may therefore be at risk for the future development of chronic airflow limitation.

Chest. 1997;111(6):1742-1749. doi:10.1378/chest.111.6.1742

Objective: To demonstrate that a consensus approach for combining prediction equations based on clinical and exercise test variables derived from different populations can stratify patients referred for possible coronary artery disease (CAD) into low-, intermediate-, and high-risk groups.

Design: Retrospective analysis of consecutive patients with complete data from exercise testing and coronary angiography referred for evaluation of possible CAD. After derivation of a logistic equation in our own training set of patients, this equation, along with two other equations developed independently by other investigators, was validated in a test set. The validation strategy for the consensus approach included the following: (1) calculation of probability scores for each patient using each logistic equation independently; (2) determination of probability thresholds in the training set to divide the patients into three groups—low risk (prevalence CAD <5%), intermediate risk (5 to 70%), and high risk (>70% prevalence of CAD); (3) using agreement among at least two of three of the prediction equations to generate "consensus" for each patient; and (4) application of the consensus approach thresholds to the test set of patients.

Settings: Two university-affiliated Veteran's Affairs medical centers.

Patients: We studied 718 consecutive men between 1985 and 1995 who had coronary angiography within 3 months of an exercise treadmill test for suspected CAD. The population was randomly divided into a training set of 429 patients and a test set of 289 patients. Patients with previous myocardial infarction or coronary artery bypass surgery, valvular heart disease, left bundle branch block, or any Q waves present on their resting ECG were excluded from the study.

Measurements: Recording of clinical and exercise test data along with visual interpretation of the ECG recordings on standardized forms and abstraction of visually interpreted angiographic data from clinical catheterization reports.

Results: We demonstrated that by using simple clinical and exercise test variables, we could improve on the standard use of ECG criteria during exercise testing for diagnosing CAD. Using the consensus approach divided the test set into populations with low, intermediate, and high risk for CAD. Since the patients in the intermediate group would be sent for further testing and would eventually be correctly classified, the sensitivity of the consensus approach is 94% and the specificity is 92%. The consensus approach controls for varying disease prevalence, missing data, inconsistency in variable definition, and varying angiographic criterion for stenosis severity. The percent of correct diagnoses increased from the 67% for standard exercise ECG analysis and from the 80% for multivariable predictive equations alone to >90% correct diagnoses for the consensus approach.

Conclusions: The consensus approach has made population-specific logistic regression equations portable to other populations. Excellent diagnostic characteristics can be obtained using simple data and measurements. The consensus approach is best applied utilizing a programmable calculator or a computer program to simplify the process of calculating the probability of CAD using the three equations.

Chest. 1997;111(6):1750-1753. doi:10.1378/chest.111.6.1750
Abstract
Chest. 1997;111(6):1754-1756. doi:10.1378/chest.111.6.1754
Abstract
Topics: cyst
Chest. 1997;111(6):1757-1758. doi:10.1378/chest.111.6.1757
Abstract
Chest. 1997;111(6):1759-1763. doi:10.1378/chest.111.6.1759

Background: Inhaled nitric oxide (NO) at levels between 5 and 80 ppm has been used experimentally to treat a variety of conditions. NO also is a common environmental air pollutant in industrial regions. As compressed hospital air is drawn from the local environment, we speculated that it may contain NO contamination, which, if present, would provide unwitting inhaled NO therapy to all subjects respiring this compressed gas.

Methods: NO levels were measured twice daily from ambient hospital air and compressed gas sources driving positive pressure ventilation from two adjacent hospitals and compared with NO levels reported daily by local Environmental Protection Agency sources. An NO chemiluminescence analyzer (Sievers 270B; Boulder, Colo) sensitive to ≥2 parts per billion was used to measure NO levels in ambient air and compressed gas.

Results: NO levels in ambient air and hospital compressed air covaried from day to day, and absolute levels of NO differed between hospitals with the difference never exceeding 1.4 ppm (range, 0 to 1.4 ppm; median, 0.07 ppm). The hospital with the highest usage level of compressed air had the highest levels of NO, which approximated ambient levels of NO. NO levels were lowest on weekends in both hospitals. We also documented inadvertent NO contamination in one hospital occurring over 5 days, which corresponded to welding activity near the intake port for fresh gas. This contamination resulted in systemwide NO levels of 5 to 8 ppm.

Conclusion: Hospital compressed air contains highly variable levels of NO that tend to covary with ambient NO levels and to be highest when the rate of usage is high enough to preclude natural degradation of NO in 21% oxygen. Assuming that inhaled NO may alter gas exchange, pulmonary hemodynamics, and outcome from acute lung injury, the role of unwitting variable NO of hospital compressed air needs to be evaluated.

Topics: nitric oxide
Chest. 1997;111(6):1763-1766. doi:10.1378/chest.111.6.1763

We report two cases of Marfan's syndrome with coexistent obstructive sleep apnea (OSA) in which treatment with nasal continuous positive airway pressure was associated with attenuation of aortic root dilatation, a serious complication of the syndrome. We speculate that coexistent OSA promotes progressive aortic dilatation in some patients with Marfan's syndrome.

Chest. 1997;111(6):1766-1767. doi:10.1378/chest.111.6.1766

Lactic acidosis previously has been reported during treatment of asthma with beta-2 agonists. However, this metabolic disturbance never had any clinical consequence. We report a case of a patient with asthma in whom beta-2 agonist administration increased dyspnea by metabolic acidosis due to a sharp increase in lactate levels (hyperlactatemia) and led to inappropriate intensification of bronchodilator therapy.

Topics: bronchodilator
Chest. 1997;111(6):1767-1769. doi:10.1378/chest.111.6.1767

Drug-induced pneumonitis is an uncommon complication of nonsteroidal anti-inflammatory drug administration. Herein is the first reported case of pneumonitis resulting from diflunisal therapy. The patient demonstrated clinical and biopsy evidence of systemic vasculitis. She responded dramatically to administration of systemic glucocorticoids.

Chest. 1997;111(6):1769-1772. doi:10.1378/chest.111.6.1769

Objective: To highlight the incidence of subglottic stenosis (SGS) as a complication of surgery for congenital heart disease and the role of single-stage laryngotracheoplasty in treating this complication.

Design: Retrospective case series.

Setting: University-based referral center specializing in surgery for congenital heart disease and complex airway problem management.

Intervention: Laryngotracheal reconstruction (LTR).

Main outcome measure: Successful airway expansion.

Results: At last follow-up, 87.5% (7 of 8) of patients remain free of obstructive airway symptoms.

Conclusion: SGS can complicate surgery for congenital heart disease in children. Single-stage LTR is an effective treatment modality for this problem.

Chest. 1997;111(6):1772-1774. doi:10.1378/chest.111.6.1772

A 53-year-old man was admitted to the hospital for management of pneumonia and a giant fluid-filled bulla. He appeared acutely ill and had persistent fever despite prolonged therapy with parenteral antibiotics and aggressive bronchial drainage. Percutaneous placement of an 8.5F catheter into the bulla enabled drainage of both fluid and air within the bulla and led to resolution of his symptoms within 24 h. This report demonstrates that drainage of giant fluid-filled bullae may lead to rapid resolution of symptoms and describes a novel management technique for this condition.

Chest. 1997;111(6):1775-1778. doi:10.1378/chest.111.6.1775

Bronchiolitis obliterans organizing pneumonia (BOOP) is an uncommon but increasingly recognized pulmonary entity that usually presents with symptoms of dyspnea, cough, and fever. The medical literature describes rare cases of hemoptysis in BOOP, with very small quantities of blood expectorated. We describe two cases of BOOP, one idiopathic and one in association with rheumatoid arthritis, in which large-quantity hemoptysis was the primary presenting symptom.

Topics: boop , hemoptysis
Chest. 1997;111(6):1778-1781. doi:10.1378/chest.111.6.1778

Intravenous haloperidol is recommended as the drug of choice to treat delirium in ICU patients. Movement disorders and other adverse events commonly occur with oral haloperidol use but are rarely seen with IV haloperidol use, and withdrawal symptoms have not been reported with short-term ICU use. We describe self-limited dyskinesia during withdrawal of high-dose continuous IV haloperidol therapy in five ICU patients.

Chest. 1997;111(6):1781-1783. doi:10.1378/chest.111.6.1781

Patients with acute lupus pneumonitis (ALP) usually have hypoxemia, patchy infiltrates evidenced on a chest x-ray film, and an incomplete response to corticosteroids with high mortality. In contrast, lupus patients with a syndrome of acute reversible hypoxemia (SARH) have hypoxemia with normal chest x-ray films and a rapid response to corticosteroids. We present a case of biopsy-proven ALP with normal initial chest x-ray films, and a normal CT scan. We hypothesize that a continuum of vascular and parenchymal abnormalities may exist in the lungs of lupus patients. This case also illustrates the insensitivity of routine chest radiographs in demonstrating mild or early pneumonitis.

Reviews

Chest. 1997;111(6):1702-1709. doi:10.1378/chest.111.6.1702

Communications to the Editor

Chest. 1997;111(6):1784. doi:10.1378/chest.111.6.1784
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Abstract
Chest. 1997;111(6):1784-1785. doi:10.1378/chest.111.6.1784-a
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Chest. 1997;111(6):1785. doi:10.1378/chest.111.6.1785
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Chest. 1997;111(6):1785. doi:10.1378/chest.111.6.1785-a
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Chest. 1997;111(6):1786. doi:10.1378/chest.111.6.1786
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Abstract
Chest. 1997;111(6):1786. doi:10.1378/chest.111.6.1786-a
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Chest. 1997;111(6):1786. doi:10.1378/chest.111.6.1786-b
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Chest. 1997;111(6):1786-1787. doi:10.1378/chest.111.6.1786-c
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Chest. 1997;111(6):1787. doi:10.1378/chest.111.6.1787
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Chest. 1997;111(6):1787-1788. doi:10.1378/chest.111.6.1787-a
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Chest. 1997;111(6):1788-1789. doi:10.1378/chest.111.6.1788
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