Cardiopulmonary function in horses during anesthetic recovery in a hydropool

Objective-To determine the cardiovascular and respiratory effects of water immersion in horses recovering from general anesthesia. Animals-healthy adult horses. Procedure-Horses were anesthetized 3 times with halothane and recovered fro m anesthesia while positioned in lateral or sternal recumbency in a padded recovery stall or while immersed in a hydropool. Cardiovascular and pulmona ry functions were monitored before and during anesthesia and during recover y until horses were standing. Measurements and calculated variables include d carotid and pulmonary arterial blood pressures (ABP and PAP respectively) , cardiac output, heart and respiratory rates, arterial and mixed venous bl ood gases, minute ventilation, end expiratory transpulmonary pressure (P-en dXes), maximal change in transpulmonary pressure (DeltaP(tp)max), total pul monary resistance (R-L), dynamic compliance (C-dyn), and work of breathing (W). Results-Immersion in water during recovery from general anesthesia resulted in values of ABP PAP P-endXes, DeltaP(tp)max, R-L, and W that were signifi cantly greater and values of C-dyn that were significantly less, compared w ith values obtained during recovery in a padded stall. Mode of recovery had no significant effect on any other measured or calculated variable. Conclusions and Clinical Relevance-Differences in pulmonary and cardiovascu lar function between horses during recovery from anesthesia while immersed in water and in a padded recovery stall were attributed to the increased ef fort needed to overcome the extrathoracic hydrostatic effects of immersion. The combined effect of increased extrathoracic pressure and PAP may contri bute to an increased incidence of pulmonary edema in horses during anesthet ic recovery in a hydropool.