Influence of pneumoperitoneum and patient positioning on preload and splanchnic blood volume in laparoscopic surgery of the lower abdomen.

STUDY
OBJECTIVE: To determine the hemodynamic effects of pneumoperitoneum and patient positioning during laparoscopic surgery of the lower abdomen.
DESIGN: Prospective study.
SETTING: University-affiliated medical center. PATIENTS: 10 ASA physical I and II female patients scheduled for laparoscopic surgery of the lower abdomen.
INTERVENTIONS: Patients were anesthetized with propofol and an alfentanil infusion, then intubated, and normoventilated. MEASUREMENTS: After intubation, a transesophageal multiplane probe for measurements of right (RVESA) and left (LVESA) ventricular end-systolic and end-diastolic areas (RVEDA and LVEDA) and ejection fraction area (RVEFa, LVEFa) was introduced; heart rate (HR) and noninvasive blood pressure (BP) were recorded every minute. Ventilation was not changed during the measurements. A transvaginal ultrasound probe was inserted to measure the diameter of the common iliac vein. Measurements were performed 15 minutes after induction of anesthesia and while patients were in the supine position (P 0), 10 minutes after CO(2) insufflation to 10 mmHg IA pressure (P 10), 10 minutes after a further increase to 15 mmHg (P 15), 10 minutes after 20 degrees Trendelenburg (P 15 T), and 20 degrees reverse Trendelenburg positions (P 15 RT). Data are shown as medians, 25th to 75th percentiles, and comparisons between P 0, P 10, P 15, and P15 T were made with the Friedman test, followed by Wilcoxon test, when significant. Data at P 15 T, P 15 RT, and P 15 were compared using the Wilcoxon test, with a p-value < 0.05 regarded as significant. MAIN
RESULTS: Pneumoperitoneum at 10 mmHg abdominal pressure caused a significant increase of LVESA by 78% (RVESA: 61%) and LVEDA by 48.5% (RVEDA: 45%). The diameter of the common iliac vein was decreased by 6%. A further increase of abdominal pressure to 15 mmHg led to an additional increase of 20% (LVESA) and 17% (LVEDA). Mean arterial pressure increased by a significant 7% at P 10, decreasing subsequently by 5% at P 15. The Trendelenburg position did not alter any hemodynamic findings. Reverse Trendelenburg position, however, caused a significant LVEDA-and RVEDA-decrease by 18% and 27%, respectively, and an increase in the diameter of the common iliac vein by 22%. The LVEFa and RVEFa decreased significantly after abdominal CO(2) insufflation by 18% each (P 10) without further change.
CONCLUSIONS: The lithotomy position and subsequent pneumoperitoneum increased preload, probably as a result of blood shifting from the abdomen to the thorax by compression of splanchnic vessels caused by the pneumoperitoneum. Careful fluid management, maintaining low abdominal pressure, and use of the reverse Trendelenburg position are favored to prevent adverse hemodynamic effects in laparoscopic surgery.