Hypoxemia During Altitude Exposure: A Meta-Analysis of Chronic Obstructive Pulmonary Disease

doi:10.1378/chest.103.2.422

Chest

Volume 103, Issue 2, February 1993, Pages 422-425

https://doi.org/10.1378/chest.103.2.422 Get rights and content

A previous study identified spirometric testing as a useful adjunct for estimating PaO₂ during altitude exposure in patients with chronic obstructive pulmonary disease (COPD). We sought to examine the validity of this finding by quantitative analysis of recent published reports. We analyzed acute hypoxic exposures from five prior studies involving 71 patients. Across all studies, the change in arterial oxygen tension per unit change in inspired oxygen partial pressure (linear slope, dPaO₂/dP₁O₂) correlated with the preexposure forced expiratory volume in 1 s (FEV₁, p<0.01). The correlation with FEV₁ held for values weighted or unweighted by sample size, with rotating deletion of each study from analysis one at a time, and with semilog slope as the dependent variable. A formula derived from the semilog slope relationship with FEV₁ gave accurate description of the mean hypoxic response in each prior study and individual responses from one study (n = 18): $In (P_{a} O_{2} alt / P_{a} O_{2} g) = k_{a} \cdot (P_{1} O_{2} alt - P_{1} O_{2} g)$

We found that FEV₁ modulated the values of k_m in this study. We conclude, based on analysis of prior studies, that preexposure arterial oxygen tension and FEV₁ both influence the prediction of PaO₂ during hypoxic exposures in patients with COPD.

Section snippets

METHODS

We evaluated mean hypoxemic responses from five published studies involving 71 patients with COPD.4, 5, 6, 7, 8 We searched for studies of patients with COPD published since 1966 that involved acute hypoxic exposure and also reported mean values for arterial blood oxygen tensions before and after exposure, barometric pressure (P_B) or altitude conditions, fraction of inspired oxygen (FIO₂) if other than ambient air, and results of spirometry, specifically FEV₁.

We developed two measures of

RESULTS

Table 1 presents mean values for selected data from the five studies involving 71 patients. Age varied from 53 to 68 years in the studies. The weighted mean age equaled 64 ±5 years (n = 61). Mean values for FEV₁ in the separate studies ranged from 0.975 to 1.400 L. Each study provided sufficient data for computation of linear and semilog slopes (Table 1, Fig 1).

Linear slope (Table 1), the change in PaO₂ per unit change in P₁O₂ as defined in equation 1, correlated with FEV₁ in a negative

DISCUSSION

We evaluated studies involving a specific disease entity with a finite range of inspired oxygen partial pressure. We do not expect the slope indices to correlate with FEV₁ in normal subjects. The indices of hypoxia which we developed, however, may be applicable to other patient care settings involving changes in inspired oxygen partial pressure.

The present study provides further evidence of the utility of FEV₁ as a predictor of PaO₂ during altitude exposure in COPD patients.⁸ In COPD and other

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Physiological predictors of Hypoxic Challenge Testing (HCT) outcomes in Interstitial Lung Disease (ILD)
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Citation Excerpt :
The evidence surrounding which ILD patients to refer for HCT is currently lacking. Predictive equations are alternatives that have been developed for use in clinical practice, to predict PaO2 at altitude [10,14–18], but have been developed almost exclusively using patients with COPD and their role in patients with ILD has not been fully defined. The primary aim of this study was to explore the concordance of existing published equations, used to predict in-flight hypoxaemia, with the outcome of HCT in patients with ILD.
Pre-flight risk assessments are currently recommended for all Interstitial Lung Disease (ILD) patients. Hypoxic challenge testing (HCT) can inform regarding the need for supplemental in-flight oxygen but variables which might predict the outcome of HCT and thus guide referral for assessment, are unknown.
A retrospective analysis of ILD patients attending for HCT at three tertiary care ILD referral centres was undertaken to investigate the concordance between HCT and existing predictive equations for prediction of in-flight hypoxia. Physiological variables that might predict a hypoxaemic response to HCT were also explored with the aim of developing a practical pre-flight assessment algorithm for ILD patients.
A total of 106 ILD patients (69 of whom (65%) had Idiopathic Pulmonary Fibrosis (IPF)) underwent HCT. Of these, 54 (51%) patients (of whom 37 (69%) had IPF) failed HCT and were recommended supplemental in-flight oxygen. Existing predictive equations were unable to accurately predict the outcome of HCT. ILD patients who failed HCT had significantly lower resting SpO₂, baseline PaO_2, reduced walking distance, FEV1, FVC and TLCO, but higher GAP index than those who passed HCT.
TLCO >50% predicted and PaO₂ >9.42 kPa were independent predictors for passing HCT. Using these discriminators, a novel, practical pre-flight algorithm for evaluation of ILD patients is proposed.
Effects of commercial air travel on patients with pulmonary hypertension
2012, Chest
Limited data are available on the effects of air travel in patients with pulmonary hypertension (PH), despite their risk of physiologic compromise. We sought to quantify the incidence and severity of hypoxemia experienced by people with PH during commercial air travel.
We recruited 34 participants for a prospective observational study during which cabin pressure, oxygen saturation (Spo₂), heart rate, and symptoms were documented serially at multiple predefined time points throughout commercial flights. Oxygen desaturation was defined as Spo₂ < 85%.
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Hypoxemia is common among people with PH traveling by air, occurring in one in four people studied. Hypoxemia was associated with lower cabin pressures, ambulation during flight, and longer flight duration. Patients with PH who will be traveling on flights of longer duration or who have a history of oxygen use, including nocturnal use only, should be evaluated for supplemental in-flight oxygen.
Recommendations for management of patients with lung disease planning a flight or high altitude travel
2011, Anales de Pediatria
Cada año un gran número de niños viajan en avión y se desplazan a lugares con altitud significativa. La mayoría de estos viajes se producen sin incidentes reseñables. Debido a los numerosos cambios socioeconómicos recientes, también ha aumentado la cantidad de pacientes con patología cardiopulmonar previa que realizan este tipo de desplazamientos. Los cambios ambientales en estos entornos, en especial la hipoxia, puede conllevar un riesgo de sucesos adversos importantes. El pediatra debe de conocer las patologías susceptibles de complicaciones en altitud, así como los estudios previos necesarios y las recomendaciones de prevención y tratamiento de las complicaciones en estas circunstancias. El Grupo de Trabajo de Técnicas de la Sociedad Española de Neumología Pediátrica se propuso la elaboración de un documento que revisara la literatura publicada sobre el tema, estableciendo unas recomendaciones de utilidad en el manejo de estos pacientes.
Every year a large number of children travel by plane and/or to places with high altitudes. Most of these journeys occur without incident. Immigration and recent socioeconomic changes have also increased the number of patients with cardiopulmonary disease who travel. Environmental changes in these places, especially lower oxygen, can lead to a risk of significant adverse events. The paediatrician must be aware of the diseases that are susceptible to complications, as well as the necessary preliminary studies and recommendations for treatment in these circumstances. The Techniques Group of the Spanish Society of Paediatric Chest Diseases undertook to design a document reviewing the literature on the subject, providing some useful recommendations in the management of these patients.
Hypoxic challenge assessment in individuals with obstructive sleep apnea
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Citation Excerpt :
According to the British Thoracic Society (BTS) recommendations published in 2002, if the resting oxygen saturation (SpO2) exceeds 95%, further assessment or supplemental in-flight oxygen is not required and if resting SpO2 is between 92% and 95% hypoxic challenge is needed only if an additional risk factor is present [3]. Most studies investigating the risk of in-flight hypoxemia have been carried out on subjects with COPD [8–10], interstitial and restrictive lung disease [10,11]. The hypoxic challenge test (HCT), also known as hypoxia inhalation test, is performed as a part of the pre-flight assessment in many centres [12,13].
The degree of arterial hypoxemia during air travel in individuals with obstructive sleep apnea (OSA) is not known. The Aerospace Medical Association considers a ground level arterial oxygen tension (PaO₂) above 9.3 kPa as safe before air travel.
Fifteen subjects with untreated OSA (mean apnea–hypopnea index [AHI] 43/h) and 14 with treated OSA (mean AHI on CPAP 1.9/h) completed an assessment including hypoxic challenge test (HCT). The groups had similar mean age, mean BMI and pre-treatment OSA severity.
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Supported by WRAMC DCI protocol No. 1724.

The opinions contained herein represent solely the views of the authors and are not to be construed as representing the views of the Department of Defense or the Department of the Army.

Presented at the annual meeting of the American Thoracic Society, May 1992, Miami Beach, Fla.

Manuscript received January 27; revision accepted June 26.

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Chest

Hypoxemia During Altitude Exposure: A Meta-Analysis of Chronic Obstructive Pulmonary Disease

Section snippets

METHODS

RESULTS

DISCUSSION

Chest

Oxygen concentrations in commercial aircraft flights

South Med J

Short-term adaptation to moderate altitude

JAMA

Air travel hypoxemia with chronic obstructive pulmonary disease

Ann Intern Med