Evaluating the Safety of Air Travel for COPD Patients
Evaluating the Safety of Air Travel for COPD Patients
Edvardsen A, Akerø A, Christensen CC, Ryg M, Skjønsberg OH
Thorax. 2012;67:964-969
Patients with respiratory disorders may be at risk for arterial hypoxia during air travel due to the decrease in ambient air pressure. Those with chronic obstructive pulmonary disease (COPD) are particularly vulnerable. What is the best way to assess the risk for an adverse event during an air flight in the COPD patient? The gold standard has been to perform a high-altitude simulation test (HAST) in which the subject breathes a gas with low oxygen concentration, 15% O2, which is equivalent to an altitude of about 8000 ft. After 15 minutes, systemic oxygen saturation is measured by arterial blood sampling. The procedure is not suitable for usual clinical practice situations, however. Therefore, investigators of a recent publication sought criteria for predicting which patients might require supplemental oxygen during an air flight using pulse oximetry rather than arterial blood gas measurements.
They subjected 100 consecutive patients with moderate to severe COPD and previous air travel intolerance to HAST. When adjusted to the lower ambient O2 breathing, arterial blood was taken for PaO2, and pulse oximetry for O2 saturation (SpO2) was performed at rest and again after a standard 6-minute walk. Seventy-three percent of patients had PaO2 levels below 50 mm Hg at rest, indicating they would be candidates for supplemental oxygen during an actual flight, the SpO2 being less than 84%. There were 8 additional patients who had a resting PaO2 greater than 50 mm Hg but whose SpO2 dropped to 84% or below during the 6-minute walk. The authors recommended that pulse oximetry, an assay that is noninvasive and readily available in the clinic, be used to predict the need for oxygen supplementation in flight, the cut-off for safety being an SpO2 of 95% at rest and 84% on exercise.
The above cut-offs were tested in a follow-up study of 50 additional patients with COPD who were subjected to HAST and arterial blood assays as well as pulse oximetry. The sensitivity of the algorithm was 100% and the specificity was 80%.
With the increase in air travel over the last several decades, many subjects with significant morbidities are flying for work or pleasure. The presence of chronic pulmonary or cardiovascular disease may present a problem, particularly for older patients who may have more than 1 comorbidity.
Although all commercial passenger airplanes have pressurized cabins, the ambient pressure in the cabin is usually equivalent to an altitude of 8000 feet above sea level. This corresponds to a PO2 of about 110 mm Hg as opposed to about 145 mm Hg at sea level. For patients with respiratory disorders whose oxygenation while breathing air may be marginal at sea level, the reduction of arterial PO2 and saturation at altitude may fall below the level of safety. The need for oxygen supplementation should be a consideration whenever the arterial oxygen saturation or pulse oxygenation falls to 84% or below. This applies not only to patients with respiratory disorders but also to those with coronary or ischemic heart disease or chronic heart failure, for whom measurement of pulse oxygenation may be recommended.
Oxygen supplementation, if needed, can sometimes be provided by air carriers. Some airlines allow patients to bring their own equipment into the cabin, provided it is a Federal Aviation Administration-approved device. Guidelines for oxygen delivery during air travel have been published by the American College of Chest Physicians and the American Thoracic Society. The need for supplemental oxygen use in flight can be readily and noninvasively determined by the criteria provided in the aforementioned study. Patients who have been found to need supplemental oxygen during flights should be advised to call their airlines, explain their needs, and inquire about airline policy on the matter.
Abstract
Air Travel and Chronic Obstructive Pulmonary Disease: A New Algorithm for Pre-flight Evaluation
Edvardsen A, Akerø A, Christensen CC, Ryg M, Skjønsberg OH
Thorax. 2012;67:964-969
Study Summary
Patients with respiratory disorders may be at risk for arterial hypoxia during air travel due to the decrease in ambient air pressure. Those with chronic obstructive pulmonary disease (COPD) are particularly vulnerable. What is the best way to assess the risk for an adverse event during an air flight in the COPD patient? The gold standard has been to perform a high-altitude simulation test (HAST) in which the subject breathes a gas with low oxygen concentration, 15% O2, which is equivalent to an altitude of about 8000 ft. After 15 minutes, systemic oxygen saturation is measured by arterial blood sampling. The procedure is not suitable for usual clinical practice situations, however. Therefore, investigators of a recent publication sought criteria for predicting which patients might require supplemental oxygen during an air flight using pulse oximetry rather than arterial blood gas measurements.
They subjected 100 consecutive patients with moderate to severe COPD and previous air travel intolerance to HAST. When adjusted to the lower ambient O2 breathing, arterial blood was taken for PaO2, and pulse oximetry for O2 saturation (SpO2) was performed at rest and again after a standard 6-minute walk. Seventy-three percent of patients had PaO2 levels below 50 mm Hg at rest, indicating they would be candidates for supplemental oxygen during an actual flight, the SpO2 being less than 84%. There were 8 additional patients who had a resting PaO2 greater than 50 mm Hg but whose SpO2 dropped to 84% or below during the 6-minute walk. The authors recommended that pulse oximetry, an assay that is noninvasive and readily available in the clinic, be used to predict the need for oxygen supplementation in flight, the cut-off for safety being an SpO2 of 95% at rest and 84% on exercise.
The above cut-offs were tested in a follow-up study of 50 additional patients with COPD who were subjected to HAST and arterial blood assays as well as pulse oximetry. The sensitivity of the algorithm was 100% and the specificity was 80%.
Viewpoint
With the increase in air travel over the last several decades, many subjects with significant morbidities are flying for work or pleasure. The presence of chronic pulmonary or cardiovascular disease may present a problem, particularly for older patients who may have more than 1 comorbidity.
Although all commercial passenger airplanes have pressurized cabins, the ambient pressure in the cabin is usually equivalent to an altitude of 8000 feet above sea level. This corresponds to a PO2 of about 110 mm Hg as opposed to about 145 mm Hg at sea level. For patients with respiratory disorders whose oxygenation while breathing air may be marginal at sea level, the reduction of arterial PO2 and saturation at altitude may fall below the level of safety. The need for oxygen supplementation should be a consideration whenever the arterial oxygen saturation or pulse oxygenation falls to 84% or below. This applies not only to patients with respiratory disorders but also to those with coronary or ischemic heart disease or chronic heart failure, for whom measurement of pulse oxygenation may be recommended.
Oxygen supplementation, if needed, can sometimes be provided by air carriers. Some airlines allow patients to bring their own equipment into the cabin, provided it is a Federal Aviation Administration-approved device. Guidelines for oxygen delivery during air travel have been published by the American College of Chest Physicians and the American Thoracic Society. The need for supplemental oxygen use in flight can be readily and noninvasively determined by the criteria provided in the aforementioned study. Patients who have been found to need supplemental oxygen during flights should be advised to call their airlines, explain their needs, and inquire about airline policy on the matter.
Abstract
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