1. Pulmonary mechanics were determined preoperatively and postoperatively in 20 patients following open-heart surgery for acquired valvular disease.
2. The surviving patients had minimal increase of the work of breathing, associated with an increase in nonelastic resistance during the early postoperative period. These changes in pulmonary mechanics are insufficient to explain the respiratory difficulties experienced by these patients.
3. In the fatal cases compliance decreased to half the preoperative level, and respiratory work increased to five times the preoperative value. In these individuals excessive work of breathing produces a significant demand on physiological resources, and controlled mechanical ventilation is indicated.
- © 1966 American Heart Association, Inc.