Dogs were placed in full pressure suits and helmets and exposed to pressures from 4 to 230 mm. Hg for periods ranging from 2 to 300 minutes. The measured cardiovascular alterations increased with pro¬longed exposure times. Pulmonary blood volume increased while the animal was breathing 100% oxygen at 4 to 8 mm. Hg pressure. The pulmonary blood volume began to decrease at a pressure of 140 mm. Hg. All increased pressures caused a decreased cardiac index and increased systemic resistance. The pressure suit used in these studies does not offer complete and prolonged protection to the animal exposed to compensated high breathing pressures.
展开▼
