Functional residual capacity during anaesthesia III: Artificial ventilation.
The helium dilution technique has been used to measure the FRC of 13 patients before and during anaesthesia with paralysis and artificial ventilation, and also in 5 conscious subjects during spontaneous and artificial ventilation without paralysis. After induction of anaesthesia the mean reduction in FRC was 297 ml or 15.4% of the preoperative value and the change was highly significant (P is smaller than 0.005). In the conscious subjects, the FRC was reduced in every case during artificial ventilation by a mean value of 99 ml or 4.1% of original value. This change was also significant. The anaesthetized patients breathed 35% oxygen before and during anaesthesia. The (A-a) PO2 difference increased from a mean value of 49.1 mm Hg before anaesthesia to a mean of 79.7 mm Hg during anaesthesia, the change being highly significant (P is smaller than 0.001). Individual changes correlated with the reduction in FRC (P is smaller than 0.005).
D000328:Adult; D000367:Age Factors; D000758:Anesthesia; D001827:Body Height; D001835:Body Weight; D006371:Helium; D006801:Humans; D007201:Indicator Dilution Techniques; D008176:Lung Volume Measurements; D008875:Middle Aged; D010100:Oxygen / Q000032:analysis / Q000097:blood; D010243:Paralysis; D010313:Partial Pressure; D011650:Pulmonary Alveoli; D012115:Residual Volume; D012119:Respiration; D012121:Respiration, Artificial; D013997:Time Factors
D006371:Helium; D010100:Oxygen