HYPERVENTILATORY CAPACITY – A PREDICTOR OF ALTITUDE SICKNESS
AbstractBackground: The aim of the study was to document link between hyperventilatory capacity andrisk for developing acute mountain sickness (AMS). Methods: This study was carried out atKarakorum Mountain ranges (Northern areas of Pakistan) from March till July 2004. 54 healthymale subjects were enrolled in this study. Arterial oxygen saturation (SpO2) of the subjects wasmeasured by the pulse oximeter at rest and after 1 minute of voluntary hyperventilation at analtitude of 2833 meters. Symptoms of acute mountain sickness (AMS) were recorded on aquestionnaire by using the Lake Louise consensus scoring system 24 hours after ascent to highaltitude. Results: Mean pre hyperventilation oxygen saturation (SpO2) was 94.07 + 0.26%whereas SpO2 after 01 minute of hyperventilation was 98.61 + 0.14% that was significantlyincreased (p<0.001). The mean increase in percent oxygen saturation of hemoglobin after oneminute of hyperventilation (hyperventilatory capacity) for the study group was 4.61 + 0.24 %while the mean symptom score was 2.06 + 0.26. It was noted that 19 (35.2%) subjects did notdevelop AMS whereas 34(63.0%) subjects had mild AMS and only one subject developedmoderate AMS. There was no case of severe AMS. The data reveals significant (P<0.01)association between hyperventilatory capacity and development of the symptoms of AMS (r= –0.664). It is evident that individuals with greater hyperventilatory capacity manifest less number ofsymptoms of mountain sickness. Conclusion: It is concluded that post hyperventilation increase inoxygen saturation at lower altitude may help to predict the susceptibility of subjects to develophigh altitude sickness.Keywords: Acute Mountain Sickness, Hyperventilatory Capacity, Hypoxia
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