Distribution of inspired gas during anesthesia and artificial ventilation

Abstract

Distribution of inspired gas was compared during spontaneous ventilation in the conscious state, during spontaneous ventilation in the anesthetized state, and during artificial ventilation in the anesthetized, paralyzed state in nine human subjects. Uniformity of distribution of inspired gas was measured using an open-circuit nitrogen-washout method. Rate and pattern of nitrogen elimination during oxygen breathing as well as calculated indices of uniformity of distribution of inspired gas and efficiency of over-all pulmonary ventilation did not vary significantly among the three conditions studied. Induction of anesthesia or substitution of artificial ventilation for spontaneous ventilation, therefore, caused no detectable change in uniformity of distribution of inspired gas. intrapulmonary mixing; respiratory changes during anesthesia Submitted on January 24, 1963