Prediction of Susceptible to Acute Mountain Sickness by Hypoxemia and Ventilatory Response during Hypoxic Exercise

Objective:To explore predictable of parameters of acute mountain sickness(AMS) by hypoxemia and hypoxic ventilatory response during hypoxic exercise,so as to supply some references to reduce the risks of AMS and improve life quality of altitude travelers.Methods:Recruit 23 male students in hypoxia chamber(~4400 m,FIO2 11.8%~11.6%) exposure 6 hours,and record the participants' AMS(LLS score) in 0.5,2,4 and 6 h.When participants' LLS ≥3 and with headache symptom defined as AMS group.After rest 30 min in hypoxia chamber,participants experienced 30 min cardiopulmonary test(supine exercise with 80 W,60 rpm),record RPE,HR,SpO2,BP and hypoxic ventilatory response every 5 min,and calculate the hypoxic ventilatory and cardio-function response indexes according aforementioned parameters.After test procedure,take the significant difference indexes as independent variables fit non-linear predictable equations.Results:After 6 h exposure,the incidence of AMS is 27%.There is no significant difference in RPE,HR,SpO2,E,VT and fR between the AMS and non AMS group when participants rest in hypoxic chamber.However,the SpO2 of AMS group is significant lower than non AMS group(P<0.05),the lowest value observed in exercise 5 min.In addition,the E of AMS group is significant lower than non AMS group(41.4±4.6 and 46.7±4.6 l/min,P<0.05,respectively).The predictable equations are LLS=0.0295(SpO2)2-4.5269(SpO2)+174.34(R2=0.7473,P<0.001) and LLS=0.0352(E)2-3.4987(E)+87.729(R2=0.307,P=0.053),respectively.And SpO2 is moderately correlated with E(R=0.394,P<0.05).Conclusions:The changes of hypoxemia(SpO2) and hypoxic ventilatory response(E) during hypoxic exercise can be use as effective indicators of AMS.The predictable accuracy of SpO2 is better than E,and there is a moderately correlation between SpO2 and E.From the perspective of test simple and reliable,the change of SpO2 during exercise has a good application prospect in predicting AMS.