Impaired Oxygenation in Surgical Patients during General Anesthesia with Controlled Ventilation

THE present study was undertaken to determine if the pattern of ventilation, by itself, may influence oxygenation during anesthesia and surgery. The hypothesis was examined that progressive pulmonary atelectasis, with increased shunting, may occur during constant ventilation whenever periodic hyperinflation (by deep breaths) is lacking, even though tidal ventilation is normal by the usual criteria, and that the impaired oxygenation, caused by atelectasis, is reversible by passive hyperinflation of the lungs.Normal tidal ventilation of the lungs serves the immediate requirements for adequate uptake of oxygen and elimination of carbon dioxide. Certainly, the maintenance of normal ventilation depends also on . . .