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Communications to the Editor |

Supplemental Oxygen During Flexible Bronchoscopy FREE TO VIEW

Rafael Golpe, MD; Alfonso Mateos, MD
Author and Funding Information

Affiliations: Monforte de Lemos Hospital Lugo, Spain,  Hope Hospital Salford, United Kingdom

Correspondence to: Rafael Golpe, MD, Unidad de Neumología, Hospital Comarcal, C/Corredoira s/n, 27400 Monforte de Lemos, Lugo, Spain; e-mail: med015254@nacom.es



Chest. 2002;121(2):664-665. doi:10.1378/chest.121.2.664
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Published online

Editor:

We have read with great interest the article by Drs. Jones and O’Driscoll recently published in CHEST (June 2001),1 regarding supplemental oxygen during flexible bronchoscopy (FB). We have conducted a study to assess the impact of FB in oxygen saturation (So2) and, while our results are similar to those found by Jones and O’Driscoll,,1 we disagree with some of their conclusions.

In our institution, we routinely used supplemental oxygen during FB when sedation, even with low-dose benzodiazepines, was used, when Pao2 before the procedure was < 65 mm Hg, or when the patient had either known cardiovascular comorbidity or several risk factors for cardiovascular disease. We prospectively studied 44 patients (31 male, 13 female) who did not fulfil these criteria.2 Lung function testing was performed before FB using a spirometer (Vitalograph 2120; Vitalograph; Lenaxa, KS). So2 was measured with a finger pulse oximeter (Minolta Pulsox 3i, 0.2 Hz; Minolta; Ramsey, NJ) from 30 min before to 30 min after the end of the procedure. Atropine, 1 mg, was administered as premedication. Terbutaline, 0.5 mL, and ipratropium bromide, 2 mL, were nebulized 20 min before the procedure to patients with known asthma and to those with a FEV1 < 50% of predicted value. No sedation was used. We used 2% lignocaine in 2-mL aliquots for local anesthesia of the vocal cords and bronchial tree, as needed. We compared oximetry parameters before, during, and after FB. We searched for differences between patients who had at least one episode of desaturation at < 90% and those who did not, using χ2 and Student’s t tests, when applicable. We searched for correlations for mean So2 during the procedure with several variables using Spearman and Pearson coefficients, when applicable. Results are expressed as mean ± SD.

Mean age of the patients was 64 ± 14 years. FEV1 was 1,613 ± 597 mL (68 ± 27%). Five patients had FEV1 < 50%. Po2 before FB was 78 ± 9 mm Hg. FB lasted 16 ± 7 min. Sixty-eight percent of patients during FB and 72% of patients after FB reached an So2 of < 90%. Mean So2 values before, during, and after FB were 95 ± 2%, 92 ± 3%, and 91 ± 3%, respectively (p = 0.0002 before vs during FB; p < 0.0001 before vs after FB). Cumulative percentages of registry time at saturations of < 90% (CT90%) before, during, and after FB were 2.2 ± 5.6%, 18.9 ± 24.5%, and 28.1 ± 35.6%, respectively (p < 0.0001 before vs during FB; p < 0.0001 before vs after FB). Sixteen percent of patients during FB and 25% of patients after FB reached CT90% of > 50%. Differences between patients who reached an So2 of < 90% during FB and those who did not were significant in age (67 ± 12 years vs 57 ± 17 years, respectively; p = 0.031), FEV1 expressed as a percentage of predicted value (62 ± 23% vs 81 ± 34%, respectively; p = 0.03), and FEV1/FVC (61 ± 16% vs 73 ± 15%, respectively; p = 0.02). We did not find differences regarding Po2 or alveolar-arterial oxygen pressure difference (P[A-a]O2) before FB, FEV1 expressed in milliliters, FVC, FB duration, or number of lung lobes affected in chest radiograph imaging. So2 during FB correlated significantly with FEV1 expressed as percentage of predicted value (r = 0.50, p = 0.01), Po2 before FB (r = 0.42, p = 0.005), P(A-a)O2 before FB (r = − 0.45, p = 0.002), and age (r = − 0.31, p = 0.04). The great dispersion of the data around the regression lines did not allow us to accurately predict which patients would have significant desaturation with FB. No significant clinical adverse events attributable to hypoxemia were noted.

Our findings show that most patients have significant oxygen desaturation with FB, even when sedation is not used and when cases with at least moderate hypoxemia before the procedure are excluded. The main (but not the only) factor related to desaturation is the existence of a obstructive ventilatory defect. In accordance with the findings of Jones and O’Driscoll,1 FEV1 could not accurately predict the desaturations, which may occur at any FEV1 level. Contrary to the authors’ conclusions, we think that this finding supports the routine use of oxygen supplementation during and after FB, at least in patients with ventilatory obstruction. The patients reported by Jones and O’Driscoll,1 did not receive oxygen when they had transient episodes (< 20 s) of drop in So2, as these temporary episodes were not considered of clinical relevance. We have indeed noted that many of the episodes of desaturation in our patients are transient, but they are also often repetitive. We think that the total time with So2 of < 90% is more important than the duration of every individual episode. Therefore, the CT90% may offer more relevant information. We have found relatively high percentages of cases with CT90% of > 50%, as reported. Also, although we agree that supplemental oxygen may increase the cost of the procedure, we fail to see how it can be considered time-consuming, as the authors state, if it is used from the beginning of the FB.,1 On the contrary, we think that starting oxygen supplementation during the FB, once the So2 falls, requires extra time from the FB team, and may indeed prolong the procedure.

The cost-effectiveness of routine oxygen supplementation is debatable, as neither our patients nor those reported by Jones and O’Driscoll1 exhibited clinical sequelae due to hypoxemia. Until more data are available, however, we think that the use of oxygen supplementation in every FB is reasonably justified, at least in those patients with ventilatory obstruction. There are other questions that merit further evaluation, such as the advisable duration of oxygen supplementation after FB. It must be noted that we have found worse saturation parameters after FB than during the procedure, and the reason for this finding also merits further study.

References

Jones, AM, O’Driscoll, R (2001) Do all patients require supplemental oxygen during flexible bronchoscopy?Chest119,1906-1909. [PubMed]
 
Golpe, R, Mateos, A Influencia de la broncofibroscopia en la saturación de O2[abstract].Arch Bronconeumol2001;37(S1),121
 
To the Editor:

We are pleased that Drs. Golpe and Mateos found our article of interest and that they had similar findings in their smaller study. Their study confirms that transient minor desaturation is common during bronchoscopy, but we differ in our response to this finding. We are unaware of any reports of adverse consequences from transient minor desaturation of the type described in both articles. Therefore, any recommendation to administer oxygen to all patients during flexible bronchoscopy must be regarded as a non–evidence-based suggestion.

Golpe and Mateos have also reported minor desaturation after the bronchoscopy procedure, and they suggest that oxygen treatment should be continued for an unspecified time after the procedure. This would increase the cost and complexity of running a bronchoscopy service (our present practice is to continue oxygen treatment after bronchoscopy only if oximetry indicates hypoxia following the procedure). The significance of transient mild desaturation (mean ± SD arterial oxygen saturation, 91 ± 3%) during the recovery phase is of very uncertain significance. The patients had no instrumentation during this phase. For example, it is known that patients with moderate COPD but normal resting oxygen saturation can have significant hypoxia develop at an oxygen pressure equal to that of a commercial airliner, with a further fall to a mean saturation of 80% during mild exercise.1 These patients were all asymptomatic, and it has never been suggested that COPD patients with normal resting blood gas should be administered oxygen during flight.

We are confident about the safety of our present practice of administering oxygen only to patients who have sustained hypoxia develop (or to those with high-risk features, such as angina).

References
Christensen, CC, Ryg, M, Refvem, OK, et al Development of severe hypoxaemia in chronic obstructive pulmonary disease patients at 2,438 m (8,000 ft) altitude.Eur Respir J2000;15,635-639. [PubMed] [CrossRef]
 

Figures

Tables

References

Jones, AM, O’Driscoll, R (2001) Do all patients require supplemental oxygen during flexible bronchoscopy?Chest119,1906-1909. [PubMed]
 
Golpe, R, Mateos, A Influencia de la broncofibroscopia en la saturación de O2[abstract].Arch Bronconeumol2001;37(S1),121
 
Christensen, CC, Ryg, M, Refvem, OK, et al Development of severe hypoxaemia in chronic obstructive pulmonary disease patients at 2,438 m (8,000 ft) altitude.Eur Respir J2000;15,635-639. [PubMed] [CrossRef]
 
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