Background: In nonobese patients, peritoneal insufflation has consiste
ntly been shown to influence parameters of preload and afterload as we
ll as cardiac output. Obese patients have an abnormal and particular c
ardiovascular status. The aim of this study was to investigate the hem
odynamic changes induced by an increase of intra-abdominal pressure in
morbidly obese patients (MOP). Methods: Standard general anesthetia w
as administered to 15 informed MOP (body mass index > 40 kg/m(2)) sche
duled for laparoscopic gastroplasty. Hemodynamic parameters were measu
red by thermodilution through a pulmonary artery catheter and through
invasive blood pressure monitoring. Results: COP insufflation with an
intra-abdominal pressure of 17 mmHg caused a significant increase of m
ean arterial pressure (MAP) (33%, P = 0.005), mean pulmonary arterial
pressure (MPAP) (40%, P = 0.001), pulmonary capillary wedge pressure (
PCWP) (41%, P = 0.001), and central venous pressure (CVP) (55%, P = 0.
001). The increase in diastolic filling pressures could be due to an i
ncrease in the filling volume or to a decrease in diastolic compliance
. Ventricular volumes were not measured but we speculate that the rise
in CVP, PCWP and MPAP is due to an increase in intrathoracic pressure
as judged by the increase of pulmonary airway pressure. Stroke volume
fell slightly (11%, P = 0.008), because of a reduction in transmural
pressure and a fall in effective preload. Cardiac output rose slightly
(16%, P = 0.005) because of an increase in heart rate (15%, P = 0.014
) probably induced by sympathetic stimulation, which only became fully
operative after 15 minutes. Conclusions: When compared to nonobese pa
tients our obese patients tolerated the pneumoperitoneum surprisingly
well, without experiencing fall in cardiac output. The hemodynamic con
sequences of peritoneal insufflation seem to be different in obese and
nonobese patients.