title: Meta-analysis of warmed versus standard temperature CO2 insufflation for laparoscopic cholecystectomy.
abstract: BACKGROUND
  There is conflicting evidence for the use of warmed, humidified carbon dioxide (CO2) for creating pneumoperitoneum during laparoscopic cholecystectomy. Few studies have reported less post-operative pain and analgesic requirement when warmed CO2 was used.
  
  
  OBJECTIVE
  This systematic review and meta-analysis aims to analyse the literature on the use of warmed CO2 in comparison to standard temperature CO2 during laparoscopic cholecystectomy.
  
  
  METHODS
  Systematic review and meta-analysis carried out in line with the PRISMA guidelines. Primary outcomes of interest were post-operative pain at 6 h, day 1 and day 2 following laparoscopic cholecystectomy. Secondary outcomes were analgesic usage and drop in intra-operative core body temperature. Standard Mean Difference (SMD) was calculated for continuous variables.
  
  
  RESULTS
  Six randomised controlled trials (RCTs) met the inclusion criteria (n = 369). There was no significant difference in post-operative pain at 6 h [3 RCTs; SMD = -0.66 (-1.33, 0.02) (Z = 1.89) (P = 0.06)], day 1 [4 RCTs; SMD = -0.51 (-1.47, 0.44) (Z = 1.05) (P = 0.29)] and day 2 [2 RCTs; SMD = -0.96 (-2.30, 0.37) (Z = 1.42) (P = 0.16)] between the warmed CO2 and standard CO2 group. There was no difference in analgesic usage between the two groups, but pooled analysis was not possible. Two RCTs reported significant drop in intra-operative core body temperature, but there were no adverse events related to this.
  
  
  CONCLUSIONS
  This review showed no difference in post-operative pain and analgesic requirements between the warmed and standard CO2 insufflation during laparoscopic cholecystectomy. Currently there is not enough high quality evidence to suggest routine usage of warmed CO2 for creating pneumoperitoneum during laparoscopic cholecystectomy.
authors.affiliation: Department of Upper Gastrointestinal Surgery, Hinchingbrooke Hospital NHS Trust, Hinchingbrooke Park, Hinchingbrooke, Huntingdon, Cambridgeshire PE29 6NT, UK.
authors.forename: Abdul R
authors.initials: AR
authors.lastname: Hakeem
authors.affiliation: Department of Upper Gastrointestinal Surgery, Hinchingbrooke Hospital NHS Trust, Hinchingbrooke Park, Hinchingbrooke, Huntingdon, Cambridgeshire PE29 6NT, UK.
authors.forename: Theodore
authors.initials: T
authors.lastname: Birks
authors.affiliation: Department of Upper Gastrointestinal Surgery, Hinchingbrooke Hospital NHS Trust, Hinchingbrooke Park, Hinchingbrooke, Huntingdon, Cambridgeshire PE29 6NT, UK.
authors.forename: Qasim
authors.initials: Q
authors.lastname: Azeem
authors.affiliation: Department of Upper Gastrointestinal Surgery, Hinchingbrooke Hospital NHS Trust, Hinchingbrooke Park, Hinchingbrooke, Huntingdon, Cambridgeshire PE29 6NT, UK.
authors.forename: Filippo
authors.initials: F
authors.lastname: Di Franco
authors.affiliation: Department of Upper Gastrointestinal Surgery, Hinchingbrooke Hospital NHS Trust, Hinchingbrooke Park, Hinchingbrooke, Huntingdon, Cambridgeshire PE29 6NT, UK.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Gergely
authors.affiliation: Department of Upper Gastrointestinal Surgery, Hinchingbrooke Hospital NHS Trust, Hinchingbrooke Park, Hinchingbrooke, Huntingdon, Cambridgeshire PE29 6NT, UK. Electronic address: adrianharris@nhs.net.
authors.forename: Adrian M
authors.initials: AM
authors.lastname: Harris
mesh_terms: D017081:Cholecystectomy, Laparoscopic; D006801:Humans; D007327:Insufflation; D011028:Pneumoperitoneum, Artificial; D013696:Temperature
keywords: CO(2); Carbon dioxide; Humidified; Laparoscopic cholecystectomy; Pneumoperitoneum; Warmed