Unbehaum 1995.

Methods	Randomised clinical trial.
Participants	Country: Germany. Number randomly assigned: 71. Postrandomisation dropouts: 10 (14.1%). Revised sample size: 61. Mean age: 47 years. Females: 44 (72.1%). Inclusion criteria: 1. Elective laparoscopic cholecystectomy. 2. Symptomatic gall stones. Exclusion criteria: 1. Conversion to open cholecystectomy. 2. Requirement for other procedures.
Interventions	Participants were randomly assigned to different pressures of pneumoperitoneum. Group 1: low pressure 8 to 10 mm Hg (n = 30). Group 2: standard pressure 14 to 16 mm Hg (n = 31).
Outcomes	The outcome reported was hospital stay.
Notes	Reason for postrandomisation dropouts was not stated. We were unable to contact the trial authors in December 2008.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: This information was not available.
Allocation concealment (selection bias)	Unclear risk	Comment: This information was not available.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Quote: "Die Vorlage der Analog skalzt erfolgte im Blindversuch, das heißt durch eine Person, der nicht bekannt war, welcher der beiden Versuchsgrttppen der Patient zugeordnet worden war" (Translation: pain scores were recorded by a person who was not aware of patient groups).
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: Postrandomisation dropouts were reported.
Selective reporting (reporting bias)	High risk	Comment: Important outcomes such as mortality and morbidity were not reported.
For‐profit bias?	Unclear risk	Comment: This information was not available.