Noninvasive measurement of cardiac output during laparoscopy.

With the use of noninvasive transthoracic impedance cardiography we have demonstrated a consistent fall in stroke volume and cardiac output without significant clinical changes in heart rate in anesthetized patients undergoing laparoscopy. Cardiac output fell to a mean value of 60% in 14 patients undergoing laparoscopy and by a mean value of 6% in four patients undergoing laparotomy. The intraabdominal pressure did not exceed 20 torr in any laparoscopy patient. Some unexplained cardiac arrests during laparoscopy in healthy females may be caused by impaired venous return due to the increased intraabdominal pressure of pneumoperitoneum. Lethal values of cardiac output could result. The routine use of transthoracic impedance cardiography would alert the anesthesiologist to a dangerous situation that cannot be determined by current routine monitoring practice.