A control system for arterial blood gases

A system was developed to control arterial O2 and CO2 partial pressure (Pao2, and Paco2) simultaneously and independently of each other. The system makes changes in inspired fractional concentration of O2 and CO2 based on values for end-tidal O2 and CO2 partial pressure. The system was applied in 23 normal subjects. In attempts to maintain a Pao2 of 90 Torr and a Paco2 of 40 Torr, arterial blood gases were 91.1 ± 6.5 (SD) Torr for Pao2 and 41.2 ± 3.2 Torr for Paco2. In attempts to maintain a Pao2 of 40 Torr and a Paco2 of 40 Torr, arterial blood gases were 40.4 ± 3.9 Torr for Pao2 and 38.9 ± 2.5 Torr for Paco2. In attempts to maintain a Pao2 of 90 Torr and a Paco2 of 55 Torr, arterial blood gases were 98.1 ± 11.5 Torr for Pao2 and 52.8 ± 3.4 Torr for Paco2. Coefficients of variations ranged from 7.1 to 11.7% for Pao2 and 6.4 to 7.8% for Paco2.