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Background: Laparoscopic adjustable gastric banding (LAGB) is commonly indicated in morbidly obese patients. There is controversy regarding the hemodynamic effects of pneumoperitoneum (PNP) in obese patients. PNP and changes in body posture have complex effects on venous return that may be detected by respiratory changes in the arterial pressure waveform. The aim of this study was to compare pneumoperitoneum-induced and reverse Trendelenburg (RT) changes in arterial pulse pressure in obese and normal-weight patients., Methods: 15 morbidly obese patients undergoing LAGB were compared to 15 normal-weight patients undergoing laparoscopic surgery. Arterial pressure was non-invasively recorded using an arterial tonometer. Respiratory changes in pulse pressure (deltaPp) were recorded in the supine position without and with PNP, and in RT position with pneumoperitoneum., Results: PNP increased deltaPp values in normal weight (P<0.001), but not in obese patients. RT position increased deltaPp values in obese patients, but did not cause additional changes in normal-weight patients., Conclusions: Unlike normal-weight patients, PNP in the supine position has minimal effect on the arterial pulse-pressure wave-form in obese patients. This observation may reflect physiological differences in total blood volume and loading conditions of the heart between morbidly obese and normal-weight patients, which affect venous return during PNP. Differences in abdominal vascular zone conditions between obese and normal weight-patients may explain these results.

Objective: To assess the accuracy of respiratory-induced systolic pressure variation and its components to detect low left ventricular preload., Design: Prospective study., Setting: University hospital., Participants: Sixty-seven patients undergoing major surgery under general anesthesia., Interventions: Transesophageal echocardiographic measurements during apnea and mechanical ventilation., Measurements and Main Results: Respiratory-induced systolic pressure variation and its components and left ventricular end-diastolic area obtained by transesophageal echocardiography were noted simultaneously. Arterial pressure indices did not allow a reliable diagnosis of a low left ventricular end-diastolic area using a cut-off value of 7.9 cm(2)/m(2) (inferior boundary of the interquartile range of the areas measured in the authors' group)., Conclusions: These results suggest that systolic pressure variations noticed after induction of general anesthesia do not reflect low left ventricular preload in nonhypotensive patients., (Copyright 2003 Elsevier Inc. All rights reserved.)