Standardizing Pneumoperitoneum for Laparoscopic Entry. Time, Volume, or Pressure: Which Is Best?

Study Objective: To establish whether time, pressure, or volume is the most reliable indicator of adequate pneumoperitoneum and, hence, the best parameter to use for safe trocar entry. Design: Prospective cohort study (Canadian Task Force classification II-2). Setting: Department of Endogynecology, Royal Hospital for Women, Sydney, Australia. Patients: One hundred thirty-three consecutive patients having gynecologic laparoscopy were recruited for the study. Of these, 100 patients were included in the analysis, and 33 were excluded. Intervention: Laparoscopic surgery. Measurements and Main Results: After umbilical Veress needle entry, pressure and volume were recorded every 20 seconds until insufflation pressure of 20 mm Hg was reached. Following trocar entry, the gas was then expelled with the patient lying flat. The depth of pneumoperitoneum was measured at intra-abdominal pressure of 5, 10, 15, and 20 mm Hg. Random effects models were used to predict the depth of pneumoperitoneum based on pressure, time, and volume. A comparison was made of the standard deviation of pneumoperitoneum distance produced at pressure of 20 mm Hg (8.56 ± 0.59) compared with that produced by a volume of 3 L (4.96 ± 1.13). Compared with volume, pressure was significantly more reliable in estimating depth of pneumoperitoneum (p