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Clinical Investigations in Critical Care |

A Randomized Clinical Trial of Continuous Aspiration of Subglottic Secretions in Cardiac Surgery Patients* FREE TO VIEW

Marin H. Kollef, MD, FCCP; Nikolaos J. Skubas, MD; Thoralf M. Sundt, MD
Author and Funding Information

*From the Department of Internal Medicine (Dr. Kollef), Pulmonary and Critical Care Division, the Department of Anesthesiology (Dr. Skubas), Division of Cardiothoracic Anesthesia, and the Department of Surgery (Dr. Sundt), Division of Cardiothoracic Surgery, Washington University School of Medicine, St. Louis, MO.

Correspondence to: Marin H. Kollef, MD, FCCP, Pulmonary and Critical Care Medicine Division, 660 S Euclid Ave, Campus Box 8052, St. Louis, MO 63110; e-mail: kollef@pulmonary.wustl.edu



Chest. 1999;116(5):1339-1346. doi:10.1378/chest.116.5.1339
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Study objectives: To determine whether the application of continuous aspiration of subglottic secretions (CASS) is associated with a decreased incidence of ventilator-associated pneumonia (VAP).

Design: Prospective clinical trial.

Setting: Cardiothoracic ICU (CTICU) of Barnes-Jewish Hospital, St. Louis, a university-affiliated teaching hospital.

Patients: Three hundred forty-three patients undergoing cardiac surgery and requiring mechanical ventilation in the CTICU.

Interventions: Patients were assigned to receive either CASS, using a specially designed endotracheal tube (Hi-Lo Evac; Mallinckrodt Inc; Athlone, Ireland), or routine postoperative medical care without CASS.

Results: One hundred sixty patients were assigned to receive CASS, and 183 were assigned to receive routine postoperative medical care without CASS. The two groups were similar at the time of randomization with regard to demographic characteristics, surgical procedures performed, and severity of illness. Risk factors for the development of VAP were also similar during the study period for both treatment groups. VAP was seen in 8 patients (5.0%) receiving CASS and in 15 patients (8.2%) receiving routine postoperative medical care without CASS (relative risk, 0.61%; 95% confidence interval, 0.27 to 1.40; p = 0.238). Episodes of VAP occurred statistically later among patients receiving CASS ([mean ± SD] 5.6 ± 2.3 days) than among patients who did not receive CASS (2.9 ± 1.2 days); (p = 0.006). No statistically significant differences for hospital mortality, overall duration of mechanical ventilation, lengths of stay in the hospital or CTICU, or acquired organ system derangements were found between the two treatment groups. No complications related to CASS were observed in the intervention group.

Conclusions: Our findings suggest that CASS can be safely administered to patients undergoing cardiac surgery. The occurrence of VAP can be significantly delayed among patients undergoing cardiac surgery using this simple-to-apply technique.

Figures in this Article

Ventilator-associated pneumonia (VAP) is a leading cause of death resulting from hospital-acquired infections with an associated crude mortality rate of 20 to 50%, depending on the specific patient population examined.15 The pathogenesis of ventilator-associated pneumonia usually requires the occurrence of two important processes: bacterial colonization of the aerodigestive tract and the aspiration of contaminated secretions into the lower airways.67 The presence of invasive medical devices (eg, endotracheal tubes, nasogastric tubes) in patients receiving mechanical ventilation are important contributors to the pathogenesis and development of VAP.,7

Endotracheal tubes play a particularly important role in the occurrence of VAP. Endotracheal tubes facilitate bacterial colonization of the tracheobronchial tree because of associated mucosal injury with their insertion and manipulation.6 These tubes also predispose the patient to lower airway aspiration of contaminated secretions by the elimination of the cough reflex, pooling of contaminated secretions above the endotracheal tube cuff, formation of a contaminated biofilm surrounding the endotracheal tube, and development of nosocomial sinusitis.612 However, the need for endotracheal intubation, particularly among patients undergoing major surgical procedures, is usually unavoidable, resulting in a pool of patients who are at risk for developing VAP.

Recently, several clinical trials have demonstrated that a simple method for decreasing the occurrence of pooled secretions above the endotracheal tube cuff (continuous aspiration of subglottic secretions[ CASS]) is associated with reductions in the occurrence of VAP.1314 To better determine the optimal use of CASS in different patient populations, we performed a clinical trial examining the effectiveness of CASS in patients undergoing cardiac surgery. The main objectives of our investigation were to determine the incidence of VAP and other important clinical outcomes among patients receiving CASS and to compare these outcomes with patients receiving routine postoperative medical care without CASS.

Study Location and Patients

The study was conducted at a university-affiliated urban teaching hospital: Barnes-Jewish Hospital (1,100 beds). During a 12-month period (December 1998 to January 1999), all patients undergoing cardiac surgery were potentially eligible for this investigation. Patients were entered into the trial if they were > 18 years of age and required mechanical ventilation in the cardiothoracic ICU (CTICU) after undergoing cardiac surgery. Patients were excluded if they were transferred from an outside hospital and had already received mechanical ventilation. The study was approved by the Washington University School of Medicine Human Studies Committee. The requirement for informed consent was waived because this study was a quality assessment of two low-risk practices already in clinical use.

Study Design

Patients were assigned to receive CASS using a specially designed endotracheal tube (Hi-Lo Evac; Mallinckrodt Inc.; Athlone, Ireland) or routine postoperative medical care without CASS. Group assignment was determined using the patient’s birth year, with those patients having odd birth years receiving CASS and those patients having even birth years receiving routine postoperative medical care without CASS.

For purposes of this investigation, ventilator circuits were defined to include the gas delivery tubing, humidifier water reservoirs or hygroscopic condenser humidifiers, water traps, in-line suction catheters, and medication delivery devices (such as metered-dose inhaler chambers or adapters). Starting at the patient’s endotracheal tube, in-line suction catheters were attached followed by a medication delivery device (if used), a hygroscopic condenser humidifier, and the gas delivery tubing. Hygroscopic condenser humidifiers were used for the first 96 h of mechanical ventilation in all patients unless specifically contraindicated (because of excessive airway secretions). Patients with contraindications to the use of hygroscopic condenser humidifiers or patients receiving mechanical ventilation for> 96 h were placed on a heated wire humidification system. On the basis of published experience, the same ventilator circuit tubing and in-line suction catheter were used throughout each patient’s course of mechanical ventilation unless these became visibly soiled or experienced a mechanical failure.1517 Heat and moisture exchangers were routinely changed every 24 h, or more frequently if visibly soiled. Respiratory therapists conducted rounds for all patients and ventilators at least every 2 h. During these rounds, the ventilator circuit was checked for condensate accumulation or air leaks, the in-line suction catheter was inspected, and the overall function of the ventilator was reviewed.

We used the following ventilators during the study period: Siemens Servo 900C (Siemens-Elema Ventilator Systems; Schaumberg, IL), Puritan-Bennett 700 Series (Puritan-Bennett Corporation; Carlsbad, CA), and Bird 8400 Series ventilators (Bird Products Corp; Palm Springs, CA). The following ventilator circuits and attachments were commercially obtained: hygroscopic condenser humidifiers (Ballard 1000; Ballard Medical Products; Draper, UT), gas delivery tubing (Hudson RCI Ventilator Set; Hudson RCI; Temecula, CA), heated water humidifier (MR730 Respiratory Humidifier; Fisher & Paykel Healthcare; New Zealand), heated wire gas delivery tubing (Isothermal Breathing Circuit; Baxter Healthcare Corp.; Deerfield, IL), in-line suction catheters (Trach Care; Ballard Medical Products), metered-dose inhaler chambers (Aerovent; Monaghan Medical Corp.; Plattsburg, NY), and water traps (Marquest Medical Products; Englewood, CO).

CASS

All study patients were intubated using the same type of endotracheal tube (Hi-Lo Evac; Mallinckrodt Inc), which incorporates a dorsal separate lumen ending into the subglottic area by creating a large elliptical dorsal opening above the cuff for aspiration of subglottic secretions.14 The size of each endotracheal tube was selected by the attending anesthesiologist. Subglottic suctioning was delivered using a standard wall suction unit, which applied continuous low intermittent suction not exceeding 20 mm Hg. The suctioning port of the Hi-Lo Evac tube was marked with a paper tag to indicate that it was a suction port. All secretions were collected in wall-mounted secretion collectors.

Data Collection

For all study patients, the following characteristics were prospectively recorded by one of the investigators: age, sex, race, premorbid lifestyle score,18severity of illness based on acute physiology and chronic health evaluation (APACHE) II19 scores, the Pao2/fraction of inspired oxygen (Fio2) ratio, and the occurrence of a witnessed aspiration event. Specific processes of medical care examined to assess risk factors for VAP were the administration of antacids or histamine-2-receptor antagonists, pharmacologic aerosol treatments during mechanical ventilation (such as bronchodilators), supine positioning of the head of the bed, tracheal reintubation, surgical tracheostomy, fiberoptic bronchoscopy, and the administration of antibiotics during the same hospitalization but before cardiac surgery. Additionally, surgical variables recorded for purposes of this investigation included the surgical procedure performed, whether perioperative antibiotic prophylaxis was administered, the use of cardiopulmonary bypass, and the cardiopulmonary bypass time.

A clinical study coordinator made daily rounds during the work week on all study patients in the CTICU. Patients entered into the study were prospectively followed for the occurrence of VAP until they were successfully weaned from mechanical ventilation, were discharged from the hospital, or died. All patients suspected of having VAP were prospectively and independently reviewed by another investigator (MHK) who was blinded to the patients’ treatment group assignments. The diagnosis of VAP was strictly based on the predetermined criteria described below. In addition to the occurrence of VAP, we assessed secondary outcomes, including lobar atelectasis, the lengths of hospitalization and ICU stay, the duration of mechanical ventilation, the number of acquired organ system derangements using the organ system failure index,20 and hospital mortality.

Definitions

All definitions were selected prospectively as part of the original study design. The premorbid lifestyle score was used as previously defined.18Zero indicated that the patient was employed without restriction; 1 indicated that the patient was independent, fully ambulatory, not employed, or employed with restriction; 2 indicated that the patient had restricted activities, could live alone and get out of the house to do basic necessities, or had severely limited exercise ability; 3 indicated that the patient was housebound, could not get out of the house unassisted, could not live alone, or could not do heavy chores; and 4 indicated that the patient was bed- or chair-bound. We calculated APACHE II scores on the basis of clinical data available from the first 24-h period of intensive care.19

The organ system failure index was modified from that used by Rubin and coworkers.20 One point was given for acquired dysfunction of each organ system: renal dysfunction, a twofold increase in baseline creatinine level or an absolute increase in baseline creatinine level of 176.8 μmol/L (2.0 mg/dL); hepatic dysfunction, an increase in total bilirubin level to > 34.2 μmol/L (2.0 mg/dL); pulmonary dysfunction, (1) a requirement for mechanical ventilation beyond 24 h after surgery for a diagnosis of pneumonia, COPD, asthma, or pulmonary edema (cardiogenic or noncardiogenic), (2) a Pao2 of < 60 mm Hg while receiving an Fio2 of ≥ 0.50, or (3) the use of at least 10 cm H2O of positive end-expiratory pressure; hematologic dysfunction, the presence of disseminated intravascular coagulation, a leukocyte count of < 1,000 cells/mm3 (1.0 × 109/L), or a platelet count of< 75 × 103/mm3 (75 × 109/L); neurologic dysfunction, a new focal deficit (such as hemiparesis after cerebral infarction) or a new generalized process (eg, seizures or coma); GI dysfunction, GI hemorrhage requiring transfusion, new ileus, or diarrhea lasting> 24 h and unrelated to previous bowel surgery; and cardiac dysfunction, acute myocardial infarction, cardiac arrest, or the new onset of congestive heart failure.

The diagnostic criteria for VAP were modified from criteria established by the American College of Chest Physicians because routine bronchoscopic or nonbronchoscopic sampling of lower airway secretions was not required.21 VAP was considered to be present when a new or progressive radiographic infiltrate developed in conjunction with either radiographic evidence of pulmonary abscess formation (ie, cavitation within preexisting pulmonary infiltrates), histologic evidence of pneumonia in lung tissue, or a positive blood or pleural fluid culture or with any two of the following: fever, leukocytosis, and purulent tracheal aspirate. Blood and pleural fluid cultures could not be related to another source, and both had to be obtained within 48 h before or after the clinical suspicion of VAP. Microorganisms recovered from blood or pleural fluid cultures also had to be identical to the organisms recovered from cultures of respiratory secretions. A new infiltrate was prospectively determined to be present if it developed after the start of mechanical ventilation or within 48 h of extubation. Persistence of the infiltrate was established if it was radiographically visible for at least 72 h. Fever was defined as an increase in the core temperature of ≥ 1°C and a core temperature of > 38.3°C. Leukocytosis was defined as a 25% increase in circulating leukocytes from baseline and a leukocyte count of> 10 × 103/mm3 (10 × 109/L). Tracheal aspirates were considered purulent if a Gram’s stain showed > 25 neutrophils per high-power field.

Prophylactic antibiotics were defined as antibiotic administration in the perioperative period aimed at reducing the incidence of nosocomial infections. Cefazolin was the routine agent administered before surgery in the preoperative area and for 24 to 48 h postoperatively. Vancomycin was also used in some high-risk patients (eg, heart transplant, valve surgery, and aortic root repair) at the surgeon’s discretion.

All chest radiographs were interpreted by a radiologist blinded to treatment group assignments. Lobar atelectasis was defined as complete opacification of a lobe with evidence of volume loss manifested by displacement of a fissure, hilum, hemidiaphragm, or narrowing of the intercostal spaces.

Statistical Analysis

We estimated sample size to provide 80% power to detect a 7.5% difference (17.5% as compared with 10.0%) in the rate of occurrence of VAP between the two study groups. We used an α-error of 0.05 (two-tailed). On the basis of these assumptions, 178 patients were needed in each of the two study groups. All comparisons were unpaired, and all tests of significance were two-tailed. Continuous variables were compared using the Student’s t test for normally distributed variables and the Wilcoxon rank-sum test for non-normally distributed variables. The χ2 or Fisher’s Exact Test was used to compare categorical variables. The primary data analysis compared the incidence of VAP between patients assigned to receive CASS and patients assigned to receive routine postoperative medical care without CASS. We used Kaplan-Meier survival analysis to compare the time of occurrence of VAP for the patients developing this complication in each study group. The log-rank test was used for statistical comparisons. The mortality rate in each group was treated as a censoring event.

Multiple logistic regression analysis was used to determine the independent risk factors for VAP. A stepwise approach was used to enter new terms into the logistic regression models, for which 0.05 was set as the limit for the acceptance or removal of new terms. In addition to patient demographics, risk factors for VAP, and surgical variables (Tables 1 and 2 ), the use of CASS was entered into the logistic regression model to determine whether it was independently associated with the development of VAP. Results of the logistic regression analysis are reported as adjusted odds ratios (ORs) with 95% confidence intervals (CIs).

Patients

Three hundred forty-nine patients requiring mechanical ventilation in the CTICU after undergoing cardiac surgery were enrolled in the study. Six patients were transferred from outside hospitals or ICUs, where they received mechanical ventilation. Therefore, 343 patients were analyzed, 160 (46.6%) of whom received CASS and 183 (53.4%) of whom received routine postoperative medical therapy without CASS. The mean (± SD) age of the patients was 63.5 ± 12.8 years (range, 21 to 92 years). At the time of study enrollment, no statistically significant differences were found between the two treatment groups for age, sex, ethnicity, premorbid lifestyle scores, APACHE II scores, the Pao2/Fio2 ratio, and risk factors for VAP (Table 1). The distribution of surgical procedures, administration of perioperative antibiotic prophylaxis, use of cardiopulmonary bypass, and duration of cardiopulmonary bypass were also similar in both treatment groups (Table 2).

VAP

Twenty-three of the 343 study patients (6.7%) developed VAP, yielding a rate of 39.7 episodes of VAP per 1,000 ventilator days. Among patients receiving CASS, 8 (5.0%) developed VAP (34.5 episodes of VAP per 1,000 ventilator days); 15 patients (8.2%) receiving routine postoperative medical therapy without CASS also developed VAP (43.2 episodes of VAP per 1,000 ventilator days; relative risk [RR], 0.61; 95% CI, 0.27 to 1.40; p = 0.238). Clinical and radiographic criteria established the presence of VAP in all patients except for two patients in the group not receiving CASS (one with positive blood culture and one with positive pleural culture for the same pathogen isolated from respiratory secretions). The 23 patients with VAP were ventilated for 3.8 ± 2.1 days before VAP was diagnosed. VAP occurred statistically later among patients receiving CASS (5.6 ± 2.3 days) than among patients who did not receive CASS (2.9 ± 1.2 days) (p = 0.006). Figure 1 provides the Kaplan-Meier curves comparing the onset of VAP for patients with this nosocomial infection in the two study groups. Survival analysis and log-rank test results indicated that the patients receiving CASS developed VAP statistically later than the patients who did not receive CASS (p = 0.002).

Multiple logistic regression analysis identified supine positioning (adjusted OR, 4.98; 95% CI, 2.29 to 10.80; p = 0.038), mechanical ventilation length of stay in 1-day increments (adjusted OR, 2.26; 95% CI, 1.93 to 2.65; p < 0.001), and APACHE II score in one-point increments (adjusted OR, 1.15; 95% CI, 1.08 to 1.23; p = 0.037) as independent risk factors for the development of VAP. The application of CASS was not found to be independently associated with the development of VAP in the multivariate analysis.

Two patients (25.0%) with VAP receiving CASS and three patients (20.0%) with VAP not receiving CASS had no growth of pathogens from their sputum cultures. The isolated pathogens for the remaining patients with VAP are shown in Table 3 . Patients receiving CASS were less likely to be infected with Staphylococcus aureus or Hemophilus influenzae than patients not receiving CASS, but this difference was not statistically significant. All eight patients receiving CASS who developed VAP also received antibiotic prophylaxis (cefazolin). Fourteen of the patients (93.3%) not receiving CASS received antibiotic prophylaxis (cefazolin, 12 patients; vancomycin, 1 patient; cefazolin and vancomycin, 1 patient).

Secondary Outcomes

Eighteen patients (11.3%) receiving CASS developed lobar atelectasis as compared with 29 patients (15.9%) without CASS (RR, 0.71; 95% CI, 0.41 to 1.23; p = 0.217). The average duration of mechanical ventilation, lengths of stay in the ICU and the hospital, and the number of acquired organ system derangements did not significantly differ between the two treatment groups (Table 4 ). The hospital mortality rate was also similar between patients with and without CASS.

Safety of CASS

No adverse patient events were associated with the use of the Hi-Lo Evac tube and the administration of CASS. One patient underwent fiberoptic bronchoscopy early in the study in the CASS group for a presumed tooth aspiration. The “tooth” image was mistakenly attributed to the radiopaque marker on the Hi-Lo Evac tube, indicating the position of the suction port above the endotracheal tube cuff.

We demonstrated that CASS can be safely applied to patients undergoing cardiac surgery using a simple technique. Although not statistically significant, the overall rate of VAP was less among patients receiving CASS than among patients not receiving CASS. Among patients developing VAP, those receiving CASS had a significant delay of 2.7 days (95% CI, 2.3 to 3.1 days) in the onset of VAP as compared with the onset of VAP in patients not receiving CASS (Fig 1). The duration of mechanical ventilation, occurrence of lobar atelectasis, lengths of stay in the ICU and hospital, hospital morality, and number of acquired organ system derangements were not statistically different between patients receiving CASS and patients not receiving CASS.

Our findings agree with those reported by Valles et al14 and Mahul et al.13 These investigators used a similar endotracheal tube; however, Mahul et al13did not use continuous aspiration and used intermittent aspiration instead. Valles et al,14 examining a general ICU population, found that the overall incidence of VAP was statistically lower among patients receiving CASS than among control patients (19.9 episodes/1,000 ventilator days vs 39.6 episodes/1,000 ventilator days; RR, 1.98; 95% CI, 1.03 to 3.82). Additionally, these authors found that episodes of VAP occurred significantly later in patients receiving CASS, which was similar to our observation. Finally, the distribution of pathogens causing VAP in the study by Valles et al14 was similar to ours, with fewer cases of VAP caused by S aureus or H influenzae among patients receiving CASS.

The main effect of CASS in our study was to delay the onset of VAP among cardiac surgery patients developing this complication. Whether this is a worthwhile goal can be questioned because none of the secondary outcomes examined were influenced by the use of CASS. This is also similar to the findings of the previous investigations, which found that the administration of CASS had no influence on hospital mortality or lengths of stay in the hospital or ICU. The overall usefulness of CASS has recently been examined by Cook et al22 who used an evidence-based approach. They concluded that individual clinicians need to decide whether the administration of CASS will significantly contribute to their VAP-prevention strategy. This will, in large part, be based on the preexisting strategies that the hospital has for VAP prevention, the additional costs associated with the use of CASS, and the clinical benefits realized with the application of CASS.

Our study has several limitations. First, we used birth years to assign patients to treatment groups and not a blinded randomization scheme. However, the treatment groups were comparable for severity of illness, demographics, and surgical procedures (Tables 1, 2), which should minimize this limitation. Second, we used a clinical diagnosis of VAP that did not rely on quantitative cultures of lower respiratory secretions obtained bronchoscopically. However, a recent study suggests that the use of clinical criteria to establish the diagnosis of VAP is acceptable because of its greater diagnostic sensitivity, compared with bronchoscopically obtained cultures, and its good correlation with hospital mortality.23Other authors have also suggested that diagnositc criteria for VAP that are not dependent on bronchoscopically obtained specimens are acceptable.2425 Third, the study was performed within a single ICU, and the results may therefore not be applicable to other institutions.

Another limitation of this investigation is the relatively small sample size examined. This has heightened importance because the occurrence of VAP was relatively uncommon among our cardiac surgery patients, although its detrimental impact on their outcomes is well described.26 The small sample size used in our study may predispose to both types I and II statistical errors. Based on the rates of VAP observed in this investigation, a sample size of 1,006 patients would be needed for the observed difference in VAP rates to be statistically significant between the two study groups (assumed power, 0.80; α, 0.05). Additionally, three patients developed VAP during the first 24 h of intensive care (one receiving CASS, two without CASS). These patients may have actually had aspiration pneumonia and not VAP, although none of these patients had a witnessed aspiration event. The clinical impact of CASS seemed to differ for this patient population compared with the patients examined by Mahul et al13and Valles et al.14 This may be related to the differences in the patient populations examined, differences in the technique of applying CASS, or use of other infection control techniques at the different hospitals. Nevertheless, our study suggests that 32 patients undergoing cardiac surgery require the application of CASS to prevent one episode of VAP, as opposed to approximately 8 patients in the study by Valles et al.14

The prevention of VAP is important because of its impact on patient outcomes, associated costs, and need for additional antibiotic therapy, which may further predispose critically ill patients to super-infection with antibiotic-resistant pathogens.27 A variety of prevention measures are currently available.7,27The benefits derived from implementing a VAP prevention program can be demonstrated in terms of both improved clinical outcomes and reduced medical care costs.2831 Such efforts require the presence of a dedicated team approach to the prevention of nosocomial infections to be most successful. Additionally, avoiding or reducing the need for endotracheal intubation may be the most important prevention strategy for this specific nosocomial infection, as suggested by several recent investigations.3233

In summary, we have demonstrated that the occurrence of VAP can be significantly delayed with the application of CASS among cardiac surgery patients developing this nosocomial infection. Future clinical trials are needed to confirm these results and to determine the overall impact of CASS as part of a more systematic approach to the prevention of VAP. Until such data become available, individual clinicians must decide how best to use their available resources to prevent the occurrence of VAP.

For editorial comment see page 1155.

Abbreviations: APACHE = acute physiology and chronic health evaluation; CASS = continuous aspiration of subglottic secretions; CI = confidence interval; CTICU = cardiothoracic ICU; fio2 = fraction of inspired oxygen; OR = odds ratio; RR = relative risk; VAP = ventilator-associated pneumonia

Supported in part by grants from the Barnes-Jewish-Christian Innovations in Healthcare Program and a research grant from Mallinckrodt Medical, Inc.

Table Graphic Jump Location
Table 1. Baseline Characteristics of Study Patients at the Time of CTICU Admission and Risk Factors for Ventilator-Associated Pneumonia During the Study Period*
* 

Values are expressed as mean ± SD or No. (%). H2 = histamine type-2 receptor.

Table Graphic Jump Location
Table 2. Surgical Study Variables*
* 

Values are expressed as mean ± SD or No. (%). CABG = coronary artery bypass graft.

 

Includes Maze procedures, repair of traumatic cardiac injuries, and atrial septal defect repairs.

Figure Jump LinkFigure 1. Comparison of onset of VAP, among patients developing this nosocomial infection, according to the presence or absence of CASS. Numbers at bottom indicate intubated patients remaining without VAP (upper row, patients without CASS; lower row, patients receiving CASS).Grahic Jump Location
Table Graphic Jump Location
Table 3. Bacteria Isolated From the Tracheal Aspirates of 23 Patients With Ventilator-Associated Pneumonia*
* 

Values are expressed as No. (%).

 

For patients receiving CASS: Enterobacter species (n = 1), Serratia marcescens (n = 1), and Stenotrophomonas maltophilia (n = 1); for patients without CASS: Proteus mirabilius (n = 3), Enterobacter species (n = 2), Klebsiella pneumoniae (n = 1), Citrobacter species (n = 1), S marcescens (n = 1), and S maltophilia (n = 1).

Table Graphic Jump Location
Table 4. Clinical Outcomes*
* 

Values are expressed as No. (%) or mean ± SD.

The authors thank Ann Doyle, RN, and Roger Imhoff, RN, for assistance in conducting this investigation.

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Kelleghan, SI, Salemi, C, Padilla, S, et al An effective continuous quality improvement approach to the prevention of ventilator-associated pneumonia.Am J Infect Control1993;21,322-330. [PubMed]
 
Gaynes, RP, Solomon, S Improving hospital-acquired infection rates: the CDC experience.Jt Comm J Qual Improv1996;22,457-467. [PubMed]
 
Nava, S, Ambrosino, N, Clini, E, et al Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease: a randomized, controlled trial.Ann Intern Med1998;128,721-728. [PubMed]
 
Antonelli, M, Conti, G, Rocco, M, et al A comparison of noninvasive positive-pressure ventilation and conventional mechanical ventilation in patients with acute respiratory failure.N Engl J Med1998;339,429-435. [PubMed]
 

Figures

Figure Jump LinkFigure 1. Comparison of onset of VAP, among patients developing this nosocomial infection, according to the presence or absence of CASS. Numbers at bottom indicate intubated patients remaining without VAP (upper row, patients without CASS; lower row, patients receiving CASS).Grahic Jump Location

Tables

Table Graphic Jump Location
Table 1. Baseline Characteristics of Study Patients at the Time of CTICU Admission and Risk Factors for Ventilator-Associated Pneumonia During the Study Period*
* 

Values are expressed as mean ± SD or No. (%). H2 = histamine type-2 receptor.

Table Graphic Jump Location
Table 2. Surgical Study Variables*
* 

Values are expressed as mean ± SD or No. (%). CABG = coronary artery bypass graft.

 

Includes Maze procedures, repair of traumatic cardiac injuries, and atrial septal defect repairs.

Table Graphic Jump Location
Table 3. Bacteria Isolated From the Tracheal Aspirates of 23 Patients With Ventilator-Associated Pneumonia*
* 

Values are expressed as No. (%).

 

For patients receiving CASS: Enterobacter species (n = 1), Serratia marcescens (n = 1), and Stenotrophomonas maltophilia (n = 1); for patients without CASS: Proteus mirabilius (n = 3), Enterobacter species (n = 2), Klebsiella pneumoniae (n = 1), Citrobacter species (n = 1), S marcescens (n = 1), and S maltophilia (n = 1).

Table Graphic Jump Location
Table 4. Clinical Outcomes*
* 

Values are expressed as No. (%) or mean ± SD.

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