Effect of accumulation of CO2 on the survival of immature pigs in a confined atmosphere. A: Gas exchange.

Our purpose is to develop a survival strategy for man trapped in a confined space. We used immature pigs to assess the applicability of findings in rats for a larger mammal. The pig consumed oxygen in a sealed chamber until hypoxic collapse. We measured blood pressure, oxygen consumption, inspired O2 and CO2, minute ventilation, ECG and body temperatures, in three groups: no accumulation of CO2; CO2 level maintained at 5%, and maximal accumulation of CO2. Hypoxic oxygen consumption and ventilation were affected by the presence of CO2. Despite the pig's body mass being two orders of magnitude greater than that of the rat, its terminal PIO2 (35.9 torr) did not differ from that of the rat (35.3 torr). Accumulation of CO 2 had no significant effect on the terminal PIO2.