Source: Annual Congress 2002 - Assessment of lung function, telemonitoring and quality of life
Disease area: Airway diseases

Abstract

Patients with lung disease could suffer complications during air travel. Clinical tests to evaluate patients at risk involve inhaling low oxygen gas mixtures (LOGM) at rest. Recent research suggests that including an exercise task would better reflect actual aircraft conditions. The purpose of this study was to evaluate the validity of two common methods of LOGM delivery at rest and with exercise.
Methods: 10 normal subjects were recruited (mean age ±] SD 30.3 ±]7) (FEV₁% pred ±] SD 102.5 ±] 13) and randomized to be given LOGM (15%±]0.2 O₂) either via a venturi mask with a nitrogen source (VM), or via a reservoir of pre-mixed gas through a one-way Hans-Rudolph valve (HRV) on separate days. After an initial resting period of 20 minutes, subjects cycled for 10 minutes at both 15 and 40% of their predetermined maximum workload. Fraction of inspired oxygen (FIO₂) was measured to determine oxygen delivery and arterial saturation by pulse oximetry (SpO₂) to determine physiological effect.
Results: The HRV was significantly more stable throughout the whole test compared to the VM (HRV: FIO₂ compared with VM: 14.62 ±] 0.34% 15.95 ±] 1.27% respectively, p<0.01). Exercise led to a significant increase in FIO₂ at both workloads while using the VM (p<0.01). SpO₂ also increased with the VM at 40% max exercise (p<0.01).
Discussion: This study shows that the VM is a potentially unreliable method for assessment of altitude simulation (with exercise) despite using the mask within its physical specifications.

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Citations should be made in the following way:
L. Seccombe, P. Kelly, P. Rogers, S. Lim (Sydney, Australia). Comparison of gas delivery systems simulating altitude exposure during rest and exercise. Eur Respir J 2002; 20: Suppl. 38, 995

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