Effects on pulmonary functions during laparoscopic manipulations under general anaesthesia

This investigation describes the effects of capnoperitoneum and Trendelenburg position on pulmonary function and arterial blood gas measurements in ten anaesthetised horses. Values were obtained with the patient in dorsal recumbency immediately before insufflation of the abdomen, directly after insufflation to 10-12 mmHg and immediately following placement of the horse in the Trendelenburg position (15-20 degrees). Values were also obtained after 25 minutes in the Trendelenburg position and 10 minutes following desufflation of the abdomen with the horse in the horizontal position. Values were measured over a three minute interval at each of the above described points. The data were recorded by a computer every ten seconds and the mean value plus standard deviation were calculated. Despite intermittent positive pressure ventilation (IPPV), insufflation of the abdomen in dorsal recumbency and head-down positioning resulted in statistically significant decreases of expiratory tidal volume, dynamic compliance, arterial partial pressure of oxygen, and significant increases in arterial partial pressure of carbon dioxide and end-expiratory carbon-dioxide. The mean values of all measured parameters returned to approximate baseline values within 10 minutes following desufflation and return to dorsal recumbency. All values remained within acceptable anaesthetic limits throughout the procedure. During laparoscopic surgery in anaesthetised horses with capnoperitoneum and head-down position, it is suggested that the surgical procedure time be kept as short as possible.