Previous studies have suggested that the ventilatory volume requirement during anesthesia for surgical operations is considerably in excess of that required while the subject is in the usual preanesthetic state.1-10 Unrecognized deficiency in carbon dioxide absorption has undoubtedly partially contributed to this requirement.11 The lung-thorax compliance has been shown to be altered during anesthesia12,13 and to be a pertinent factor in relating ventilatory volume to respiratory tract pressure. The work required to effect the desired ventilatory adequacy is to be considered in this paper.
The total work of breathing in patients with normal and with diseased cardiorespiratory systems, made before, during, and after general anesthesia for surgical operations, has been calculated from measurements of elastic resistance (reciprocal of lung-thorax compliance) and nonelastic resistance to breathing. The effects of various factors on the work of breathing have been considered. The changes in lung-thorax compliance that were found to