A computerizing control system for evaluating respiratory, circulatory and metabolic states of surgical patients under general anesthesia

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1. Using a mass-spectrometer in combination with a computer system, uptake and elimination of two inhalational anesthetic agents (isoflurane and sevoflurane) were investigated in clinical anesthesia. Although the rate of uptake of the two agents decreased with time, the rate of decrease in uptake was smaller in obese patients than in non-obese patients. The rate of rise with time in alveolar concentration of anesthetic ( F_A ) was more gradual in obese patients than in non-obese patients. These results suggest that uptake of volatile anesthetics by adipose tissues was more active in obese patients than in non-obese patients. The fact that the rate of rise in F_A/F_I with time during isoflurane inhalation was smaller than during sevoflurane inhalation might have resulted from a difference in blood/gas partition coefficient between two agents.2. The effect of infiltration of epinephrine solution into oral submucosal tissues on oxygen consumption ( VO_2) and CO_2 production ( VCO_2 ) was studied in patients scheduled for oral surgery. The epinephrine infiltration produced increases in both VO_2 and VCO_2 and these effect persisted for at least 30 minutes. It is assumed that the increases in both VO_2 and VCO_2 after epinephrine infiltration were mainly due to an increase in systemic metabolism induced by epinephrine.3. Effect of hypocapnia on VO_2 was investigated in clinical anesthesia. A moderate degree of hypocapnia ( PaCO_2 = 30 mmHg ) did not produce a significant increase in VO_2 in patients under isoflurane or sevoflurane anesthesia.