Influence of pneumoperitoneum and patient positioning on respiratory system compliance

Study Objective: To investigate the influence of pneumoperitoneum (PP) and posture on respiratory compliance and ventilation pressures. Design: Prospective, single blind trial. Patients: 10 female ASA physical status I and II patients scheduled for ele ctive gynecologic laparoscopy. Setting: University medical center. Interventions: Anesthesia was performed as total TV anesthesia (TIVA) with propofol, alfentanil, and atracurium. A fter induction of anesthesia and orotracheal intubation, the lungs were ven tilated to maintain partial pressure of CO2 (PETCO2) of 30 +/- 3 mmHg. Vent ilation was kept constant. As gas mixture oxygen and air 1:1 was used witho ut positive end-expiratory pressure (PEEP). Measurements: Measurements were taken before and after creation of pneumope ritoneum with an intraabdominal pressure (IAP) of 10 mmHg, of 15 mmHg in 20 degrees head-down tilt, then in 20 degrees head-up tilt, and after deflati on of PP. We determined peak inspiratory pressure (PIP), mean airway pressu re (mPaw), PETCO2, expiratory minute volume (V(over dot)(E)), heart rate (H R), and systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP). Respiratory system compliance (C-eff rs) was calculated as quotient of tida l volume (VI) and PIP. Main Results: After creation of PP (IAP 10 mmHg), there was a significant i ncrease of median PIP (3 cmH(2)O), mPaw (I cm H2O) and arterial pressure (B P), (ALA-P by 7 mmHg), C-eff rs decreased by 6 mL . cm H2O-1. Increase of I AP to 15 mmHg led to a further increase of PIP (2 cm H2O) and mPaw (1 cm H2 O), and a further decrease of C-eff rs by 5 mL cm H2O-1; BP decreased (MAP by 5.5 mmHg). Head-up or head down positions showed no significant hemodyna mic or pulmonary changes. P(ET)CO(2)increased from 29.5 to 36 mmHg at an IA P of 15 mmHg, but then no further changes were noticed. Five minutes after deflation of pneumoperitoneum all values returned to baseline levels. Conclusions: Creation of PP at an IAP of 15 mmHg reduced respiratory system compliance, and increased peak inspiratory and mean airway pressures, whic h quickly returned to normal values after deflation. Head-down or head-up p osition did not further alter those parameters. (C) 2001 by Elsevier Scienc e Inc.