Simulated airplane flight increases plasma lactate in fetal rabbits

We studied the effect of 9 h of simulated airplane cabin conditions at crui sing altitude (8,000 feet, inspired oxygen equivalent to 15% O-2 at sea lev el) on fetal plasma lactate in near-term pregnant rabbits. Controls (n = 19 ) spent 9 h at sea level (21% O-2). Study group I(n = 21) experienced airpl ane cabin conditions. Study group II (n = 17) was studied at 8,000 feet wit h the inspired O-2 concentration normalized to sea level. Study group III ( n = 19) remained at sea level breathing 15% O-2. Before ending each exposur e, fetal blood sampling for lactate was performed under ultrasound guidance . Maternal lactates were obtained before and after sampling fetuses. Wilcox on signed rank test,analysis of variance, and Bonferroni's method were used as appropriate. P < 0.05 denoted statistical significance. Study group I ( altitude/hypoxia) had higher fetal lactates than controls (sea level/normox ia) and study group II (altitude/normoxia). Fetal lactates in study group I (altitude/hypoxia) were higher than in study group III (sea level/hypoxia). Maternal lactates were lower after fetal sampling. Fetal lactic acidemia w as observed after 9 h of airplane cabin conditions. This was attributed to the combined effect of the lowered oxygen concentration and the decrease in atmospheric pressure.