Aina Akerø

Akerø A, Christensen CC, Edvardsen A, Ryg M, Skjønsberg OH. Pulse oximetry in the preflight evaluation of patients with chronic obstructive pulmonary disease. Aviat Space Environ Med 2008; 79:518–24. Introduction: In a British Thoracic Society (BTS) statement on preflight evaluation of patients with respiratory disease, sea level pulse oximetry (Spo_2sl) is recommended as an initial assessment. The present study aimed to evaluate if the BTS algorithm can be used to identify chronic obstructive pulmonary disease (COPD) patients in need of supplemental oxygen during air travel, i.e. patients with an in-flight P_ao₂ < 6.6 kPa (50 mmHg). Methods: There were 100 COPD patients allocated to groups according to the BTS algorithm: Spo_2sl > 95%, Spo_2sl 92–95% without additional risk factors; Spo_2sl 92–95% with additional risk factors; Spo_2sl < 92%; and patients using domiciliary oxygen. Pulse oximetry, arterial blood gases, and an hypoxia-altitude simulation test (HAST) to simulate a cabin altitude of 2438 m (8000 ft), were performed. Results: The percentage of patients in the various groups dropping below 6.6 kPa during HAST were: Spo_2sl > 95%: 30%; Spo_2sl 92–95% without additional risk factors: 67%; Spo_2sl 92–95% with additional risk factors: 70%; Spo_2sl < 92%: 83%; and patients using domiciliary oxygen: 81%. In patients dropping below P_ao₂ 6.6 kPa, supplemental oxygen of median 1 L · min^{− 1} was needed to exceed this limit. Discussion: If in-flight P_ao₂ ≥ 6.6 kPa is regarded as a strict requirement, the use of pulse oximetry as an initial assessment in the preflight evaluation of COPD patients, as suggested by the BTS, might not discriminate adequately between patients who fulfill the indications for supplemental oxygen during air travel, and patients who can travel without such treatment.

The aim of the study was to investigate hypoxaemia in chronic obstructive pulmonary disease patients during a commercial flight.The effect of a commercial flight, lasting 5 h 40 min, on arterial blood gas levels and symptoms in 18 chronic obstructive pulmonary disease patients with a pre-flight percutaneous oxygen saturation of ≥94% and self-reported ability to walk 50 m without severe dyspnoea was studied.The arterial oxygen tension (Pa,O₂) decreased from sea level to cruising altitude (10.3±1.2versus8.6±0.8 kPa), but, thereafter, except for one patient, remained stable throughout the flight. During light exercise, however, there was further desaturation (percutaneous oxygen saturation 90±4versus87±4%). After 4 h, a decrease in arterial carbon dioxide tension (5.0±0.4versus4.8±0.4 kPa) and an increase in cardiac frequency (87±13versus95±13 beats·min^-1) were observed. A pre-flightPa,O₂of >9.3 kPa did not secure an acceptable in-flightPa,O₂. Aerobic capacity showed the strongest correlation with in-flightPa,O₂.In conclusion, following an initial decrease in arterial oxygen tension, chronic obstructive pulmonary disease patients in a stable state of their disease seem to maintain a stable arterial oxygen tension throughout a flight of intermediate duration, except when walking along the aisle. However, a decrease in arterial carbon dioxide tension, indicating compensatory hyperventilation, could imply a risk of respiratory fatigue during longer flights.