title: Standardizing pneumoperitoneum for laparoscopic entry. Time, volume, or pressure: which is best?
abstract: 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.
  
  
  METHODS
  Prospective cohort study (Canadian Task Force classification II-2).
  
  
  METHODS
  Department of Endogynecology, Royal Hospital for Women, Sydney, Australia.
  
  
  METHODS
  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.
  
  
  METHODS
  Laparoscopic surgery.
  
  
  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 < .001) because it exhibited the least variance. Further 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 at 3 minutes (7.82 ± 1.19). Compared with time, pressure was significantly more reliable in depth of pneumoperitoneum (p < .001) because it exhibited the least variance. These results demonstrate that, compared with volume and time, pressure is the most reliable predictor of pneumoperitoneum depth because it exhibits the least variance (p < .001).
  
  
  CONCLUSIONS
  Pressure is the most reliable predictor of pneumoperitoneum before trocar entry in laparoscopic surgery.
authors.affiliation: Worcestershire Acute Hospitals NHS Trust, Worcester, England. angus.thomson@worcsacute.nhs.uk
authors.forename: Angus J M
authors.initials: AJ
authors.lastname: Thomson
authors.forename: Mamdouh N
authors.initials: MN
authors.lastname: Shoukrey
authors.forename: Isla
authors.initials: I
authors.lastname: Gemmell
authors.forename: Jason A
authors.initials: JA
authors.lastname: Abbott
mesh_terms: D000328:Adult; D005260:Female; D013509:Gynecologic Surgical Procedures / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D006801:Humans; D010535:Laparoscopy / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D015233:Models, Statistical; D011028:Pneumoperitoneum, Artificial / Q000379:methods / Q000592:standards*; D011312:Pressure; D011446:Prospective Studies; D013997:Time Factors