Low pressure versus standard pressure pneumoperitoneum in laparoscopic cholecystectomy

Cochrane Database of Systematic Reviews

Volumn 2014, Issue 3, 2014, Pages

  Gurusamy, Kurinchi Selvan ^a   Vaughan, Jessica ^a   Davidson, Brian R ^a  

^a ROYAL FREE HOSPITAL   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON DIOXIDE;

ABDOMINAL PRESSURE; ABDOMINAL WALL; ACALCULOUS CHOLECYSTITIS; ADVERSE EVENT; ARTIFICIAL PNEUMOPERITONEUM; CONFIDENCE INTERVAL; CONVERSION TO OPEN SURGERY; GALLBLADDER DISEASE; GALLSTONE; HOSPITALIZATION; HUMAN; INTERMETHOD COMPARISON; LAPAROSCOPIC CHOLECYSTECTOMY; LOW PRESSURE PNEUMOPERITONEUM; LOW RISK PATIENT; OPERATION DURATION; PRACTICE GUIDELINE; PRIORITY JOURNAL; QUALITY OF LIFE; REVIEW; RISK ASSESSMENT; RISK BENEFIT ANALYSIS; STANDARD PRESSURE PNEUMOPERITONEUM; SURGICAL MORTALITY; SURGICAL RISK; SURGICAL TECHNIQUE; SYSTEMATIC REVIEW; TREATMENT OUTCOME; CHOLECYSTECTOMY; GASTROINTESTINAL RADIOGRAPHY; LENGTH OF STAY; META ANALYSIS; METHODOLOGY; PRESSURE; RANDOMIZED CONTROLLED TRIAL (TOPIC);

CARBON DIOXIDE; CHOLECYSTECTOMY, LAPAROSCOPIC; CONVERSION TO OPEN SURGERY; HUMANS; LENGTH OF STAY; PNEUMOPERITONEUM, ARTIFICIAL; PRESSURE; RANDOMIZED CONTROLLED TRIALS AS TOPIC;

EID: 84907419121     PISSN: None     EISSN: 1469493X     Source Type: Journal    
DOI: 10.1002/14651858.CD006930.pub3     Document Type: Review

References (98)

1. Barczynski M, Herman RM. Influence of different pressures of pneumoperitoneum on the autonomic system function during laparoscopy. Folia Medica Cracoviensia 2002;43(1-2):51-8.
2. Barczynski M, Herman RM. A prospective randomized trial on comparison of low-pressure (LP) and standard-pressure (SP) pneumoperitoneum for laparoscopic cholecystectomy. Surgical Endoscopy 2003;17(4):533-8.
3. Basgul E, Bahadir B, Celiker V, Karagoz AH, Hamaloglu E, Aypar U. Effects of low and high intra-abdominal pressure on immune response in laparoscopic cholecystectomy. Saudi Medical Journal 2004;25(12):1888-91.
4. Celik V, Salihoglu Z, Demiroluk S, Unal E, Yavuz N, Karaca S, et al.Effect of intra-abdominal pressure level on gastric intramucosal pH during pneumoperitoneum. Surgical Laparoscopy Endoscopy & Percutaneous Techniques 2004;14(5):247-9.
5. Celik AS, Firat N, Celebi F, Guzey D, Kaplan R, Birol S, et al.Laparoscopic cholecystectomy and postoperative pain: is it affected by intra-abdominal pressure?. Surgical Laparoscopy Endoscopy & Percutaneous Techniques 2010;20(4):220-2.
6. Chok KS, Yuen WK, Lau H, Fan ST. Prospective randomized trial on low-pressure versus standard-pressure pneumoperitoneum in outpatient laparoscopic cholecystectomy. Surgical Laparoscopy Endoscopy & Percutaneous Techniques 2006;16(6):383-6.
7. Dexter SP, Vucevic M, Gibson J, McMahon MJ. Hemodynamic consequences of high- and low-pressure capnoperitoneum during laparoscopic cholecystectomy. Surgical Endoscopy 1999;13(4):376-81.
8. Eryilmaz HB, Memis D, Sezer A, Inal MT. The effects of different insufflation pressures on liver functions assessed with LiMON on patients undergoing laparoscopic cholecystectomy. The Scientific World Journal 2012;2012:172575.
9. Hasukic S. Postoperative changes in liver function tests - Randomized comparison of low- and high-pressure laparoscopic cholecystectomy. Surgical Endoscopy 2005;19(11):1451-5.
10. Ibraheim OA, Samarkandi AH, Alshehry H, Faden A, Farouk EO. Lactate and acid base changes during laparoscopic cholecystectomy. Middle East Journal of Anesthesiology 2006;18(4):757-68.
11. 2 pneumoperitoneum for laparoscopic cholecystectomy. Egyptian Journal of Anaesthesia 2005;21(4):337-40.
12. Joshipura VP, Haribhakti SP, Patel NR, Naik RP, Soni HN, Patel B, et al.A prospective randomized, controlled study comparing low pressure versus high pressure pneumoperitoneum during laparoscopic cholecystectomy. Surgical Laparoscopy, Endoscopy & Percutaneous Techniques 2009;19(3):234-40.
13. Kandil TS, El Hefnawy E. Shoulder pain following laparoscopic cholecystectomy: factors affecting the incidence and severity. Journal of Laparoendoscopic and Advanced Surgical Techniques. Part A 2010;20(8):677-82.
14. Kanwer DB, Kaman L, Nedounsejiane M, Medhi B, Verma GR, Bala I. Comparative study of low pressure versus standard pressure pneumoperitoneum in laparoscopic cholecystectomy - a randomised controlled trial. Tropical Gastroenterology 2009;30(3):171-4.
15. Karagulle E, Turk E, Dogan R, Ekici Z, Moray G. The effects of different abdominal pressures on pulmonary function test results in laparoscopic cholecystectomy. Surgical Laparoscopy, Endoscopy & Percutaneous Techniques 2008;18(4):329-33.
16. Koc M, Ertan T, Tez M, Kocpinar MA, Kilic M, Gocmen E, et al.Randomized, prospective comparison of postoperative pain in low-versus high-pressure pneumoperitoneum. Australian and New Zealand Journal of Surgery 2005;75(8):693-6.
17. Perrakis E, Vezakis A, Velimezis G, Savanis G, Deverakis S, Antoniades J, et al.Randomized comparison between different insufflation pressures for laparoscopic cholecystectomy. Surgical Laparoscopy Endoscopy & Percutaneous Techniques 2003;13(4):245-9.
18. Pier A, Benedic M, Mann B, Buck V. Post-laparoscopic pain syndrome - results of a prospective randomized study. Der Chirurg 1994;65(3):200-8.
19. Polat C, Yilmaz S, Serteser M, Koken T, Kahraman A, Dilek ON. The effect of different intraabdominal pressures on lipid peroxidation and protein oxidation status during laparoscopic cholecystectomy. Surgical Endoscopy 2003;17(11):1719-22.
20. Sandhu T, Yamada S, Ariyakachon V, Chakrabandhu T, Chongruksut W, Ko-Iam W. Low-pressure pneumoperitoneum versus standard pneumoperitoneum in laparoscopic cholecystectomy, a prospective randomized clinical trial. Surgical Endoscopy 2009;23(5):1044-7.
21. Sefr R, Puszkailer K, Frána J, Penka I. [Effect of carbon dioxide pneumoperitoneum on selected parameters of the acid-base equilibrium in laparoscopic cholecystectomy]. Rozhledy v Chirurgii 2001;80(4):206-12.
22. Sefr R, Puszkailer K, Jagos F. Randomized trial of different intraabdominal pressures and acid-base balance alterations during laparoscopic cholecystectomy. Surgical Endoscopy 2003;17(6):947-50.
23. Topal A, Celik JB, Tekin A, Yuceaktas A, Otelcioglu S. The effects of 3 different intra-abdominal pressures on the thromboelastographic profile during laparoscopic cholecystectomy. Surgical Laparoscopy, Endoscopy & Percutaneous Techniques 2011;21(6):434-8.
24. Torres K, Torres A, Staskiewicz GJ, Chroscicki A, Lo T, Maciejewski R. A comparative study of angiogenic and cytokine responses after laparoscopic cholecystectomy performed with standard- and low-pressure pneumoperitoneum. Surgical Endoscopy 2009;23(9):2117-23.
25. Unbehaum N, Feussner H, Siewert J R. Low-pressure insufflation technique in the laparoscopic cholecystectomy. Minimal Invasive Chirurgie 1995;4:10-5.
26. Wallace DH, Serpell MG, Baxter JN, O'Dwyer PJ. Randomized trial of different insufflation pressures for laparoscopic cholecystectomy. British Journal of Surgery 1997;84(4):455-8.
27. Barczynski M, Herman RM. Low-pressure pneumoperitoneum combined with intraperitoneal saline washout for reduction of pain after laparoscopic cholecystectomy: a prospective randomized study. Surgical Endoscopy 2004;18(9):1368-73.
28. Beqiri AI, Domi RQ, Sula HH, Zaimi EQ, Petrela EY. The combination of infiltrative bupivacaine with low-pressure laparoscopy reduces postcholecystectomy pain. A prospective randomized controlled study. Saudi Medical Journal 2012;33(2):134-8.
29. Brokelman WJA, Holmdahl L, Bergstrom M, Falk P, Klinkenbijl JHG, Reijnen M. Peritoneal fibrinolytic response to various aspects of laparoscopic surgery: a randomized trial. Journal of Surgical Research 2006;136(2):309-13.
30. Brokelman WJA, Holmdahl L, Bergstrom M, Falk P, Klinkonbijl JHG, Reijnen MMPJ. Peritoneal transforming growth factor beta-1 expression during laparoscopic surgery: a clinical trial. Surgical Endoscopy 2007;21(9):1537-41.
31. Esmat ME, Elsebae MMA, Nasr MMA, Elsebaie SB. Combined low pressure pneumoperitoneum and intraperitoneal infusion of normal saline for reducing shoulder tip pain following laparoscopic cholecystectomy. World Journal of Surgery 2006;30(11):1969-73.
32. Giraudo G, Brachet Contul R, Caccetta M, Morino M. Gasless laparoscopy could avoid alterations in hepatic function. Surgical Endoscopy 2001;15(7):741-6.
33. Morino M, Giraudo G, Festa V. Alterations in hepatic function during laparoscopic surgery. An experimental clinical study. Surgical Endoscopy 1998;12(7):968-72.
34. Parikh H, Mehta M. A study of QT interval and QT dispersion during laparoscopic cholecystectomy. Indian Journal of Anaesthesia 2009;53(2):193-6.
35. Sandoval-Jimenez C, Mendez-Sashida G, Cruz-Marquez-Rico L, Cardenas-Victorica R, Guzman-Esquivel H, Luna-Silva M, et al.[Postoperative pain in patients undergoing elective laparoscopic cholecystectomy with low versus standard-pressure pneumoperitoneum. A randomized clinical trial.]. Revista de Gastroenterologia de Mexico 2009;74(4):314-20.
36. Sarli L, Costi R. Prospective randomized trial of low-pressure pneumoperitoneum for reduction of shoulder-tip pain following laparoscopy. British Journal of Surgery 2000;87(9):1161-5.
37. Tou S, Singh-Ranger D. Randomized trial of different Intraabdominal pressures and acid-base balance alterations during laparoscopic cholecystectomy. Surgical Endoscopy 2004;18(5):872.
38. Yasir M, Mehta KS, Banday VH, Aiman A, Masood I, Iqbal B. Evaluation of post operative shoulder tip pain in low pressure versus standard pressure pneumoperitoneum during laparoscopic cholecystectomy. The Surgeon 2012;10(2):71-4.
39. Alijani A, Hanna GB, Cuschieri A. Abdominal wall lift versus positive-pressure capnoperitoneum for laparoscopic cholecystectomy - randomized controlled trial. Annals of Surgery 2004;239(3):388-94.
40. American Association of Anesthiologists. ASA Physical Status Classification System. www.asahq.org/clinical/physicalstatus.htm (accessed 7 August 2013).
41. Attili AF, De Santis A, Capri R, Repice AM, Maselli S. The natural history of gallstones: the GREPCO experience. The GREPCO Group. Hepatology 1995;21(3):655-60.
42. Ballal M, David G, Willmott S, Corless DJ, Deakin M, Slavin JP. Conversion after laparoscopic cholecystectomy in England. Surgical Endoscopy 2009;23(10):2338-44.
43. Bates T, Harrison M, Lowe D, Lawson C, Padley N. Longitudinal study of gall stone prevalence at necropsy. Gut 1992;33(1):103-7.
44. Berger MY, van der Velden JJ, Lijmer JG, de Kort H, Prins A, Bohnen AM. Abdominal symptoms: do they predict gallstones? A systematic review. Scandinavian Journal of Gastroenterology 2000;35(1):70-6.
45. Brok J, Thorlund K, Gluud C, Wetterslev J. Trial sequential analysis reveals insufficient information size and potentially false positive results in many meta-analyses. Journal of Clinical Epidemiology 2008;61:763-9.
46. Brok J, Thorlund K, Wetterslev J, Gluud C. Apparently conclusive meta-analyses may be inconclusive - Trial sequential analysis adjustment of random error risk due to repetitive testing of accumulating data in apparently conclusive neonatal meta-analyses. International Journal of Epidemiology 2009;38(1):287-98.
47. Casati A, Valentini G, Ferrari S, Senatore R, Zangrillo A, Torri G. Cardiorespiratory changes during gynaecological laparoscopy by abdominal wall elevation: comparison with carbon dioxide pneumoperitoneum. British Journal of Anaesthesia 1997;78(1):51-4.
48. Cordoba G, Schwartz L, Woloshin S, Bae H, Gotzsche PC. Definition, reporting, and interpretation of composite outcomes in clinical trials: systematic review. BMJ 2010;341:c3920.
49. Copenhagen Trial Unit. TSA - Trial Sequential Analysis. http://ctu.dk/tsa/ 2011 (accessed 7 August 2013).
50. DeMets DL. Methods for combining randomized clinical trials: strengths and limitations. Statistics in Medicine 1987;6(3):341-50.
51. DerSimonian R, Laird N. Meta-analysis in clinical trials. Controlled Clinical Trials 1986;7(3):177-88.
52. Dexter SPL, Martin IG, Marton J, McMahon MJ. Long operation and the risk of complications from laparoscopic cholecystectomy. British Journal of Surgery 1997; Vol. 84, issue 4:464-6. [DOI: 10.1002/bjs.1800840410]
53. Dolan JP, Diggs BS, Sheppard BC, Hunter JG. The national mortality burden and significant factors associated with open and laparoscopic cholecystectomy: 1997-2006. Journal of Gastrointestinal Surgery 2009;13(12):2292-301.
54. Egawa H, Morita M, Yamaguchi S, Nagao M, Iwasaki T, Hamaguchi S, et al.Comparison between intraperitoneal CO2 insufflation and abdominal wall lift on QT dispersion and rate-corrected QT dispersion during laparoscopic cholecystectomy. Surgical Laparoscopy Endoscopy & Percutaneous Techniques 2006;16(2):78-81.
55. Egger M, Davey SG, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ (Clinical Research Ed.) 1997;315(7109):629-34.
56. Galizia G, Prizio G, Lieto E, Castellano P, Pelosio L, Imperatore V, et al.Hemodynamic and pulmonary changes during open, carbon dioxide pneumoperitoneum and abdominal wall-lifting cholecystectomy. A prospective, randomized study. Surgical Endoscopy 2001;15(5):477-83.
57. Giger UF, Michel JM, Opitz I, Inderbitzin DT, Kocher T, Krahenbuhl L. Risk factors for perioperative complications in patients undergoing laparoscopic cholecystectomy: analysis of 22, 953 consecutive cases from the Swiss Association of Laparoscopic and Thoracoscopic Surgery database. Journal of American College of Surgeons 2006;203(5):723-8.
58. Giger U, Ouaissi M, Schmitz SF, Krahenbuhl S, Krahenbuhl L. Bile duct injury and use of cholangiography during laparoscopic cholecystectomy. The British Journal of Surgery 2011;98(3):391-6.
59. Glasgow RE, Cho M, Hutter MM, Mulvihill SJ. The spectrum and cost of complicated gallstone disease in California. Archives of Surgery 2000;135(9):1021-5; discussion 1025-7.
60. Gluud C, Nikolova D, Klingenberg SL, Alexakis N, Als-Nielsen B, Colli A, et al.Cochrane Hepato-Biliary Group. About The Cochrane Collaboration (Cochrane Review Groups (CRGs)). 2013, Issue 7. Art. No.: LIVER.
61. GREPCO . Prevalence of gallstone disease in an Italian adult female population. Rome group for the epidemiology and prevention of cholelithiasis (GREPCO). American Journal of Epidemiology 1984;119(5):796-805.
62. GREPCO . The epidemiology of gallstone disease in Rome, Italy. Part i. Prevalence data in men. The Rome group for epidemiology and prevention of cholelithiasis (GREPCO). Hepatology 1988;8(4):904-6.
63. Gurusamy KS, Koti R, Samraj K, Davidson BR. Abdominal lift for laparoscopic cholecystectomy. Cochrane Database of Systematic Reviews 2012, Issue 5. [DOI: 10.1002/14651858.CD006574.pub3]
64. Gurusamy KS, Vaughan J, Ramamoorthy R, Fusai G, Davidson BR. Miniports versus standard ports for laparoscopic cholecystectomy. Cochrane Database of Systematic Reviews 2013, Issue 8. [DOI: 10.1002/14651858.CD006804.pub3]
65. Gurusamy KS, Vaughan J, Toon C, Davidson BR. Pharmacological interventions for prevention or treatment of post-operative pain in patients undergoing laparoscopic cholecystectomy. Cochrane Database of Systematic Reviews 2014, Issue (under editorial). [DOI: 10.1002/14651858.CD008261]
66. Loizides S, Gurusamy KS, Nagendran M, Rossi M, Guerrin GP, Davidson BR. Wound infiltration with local anaesthetic agents for laparoscopic cholecystectomy. Cochrane Database of Systematic Reviews 2014, Issue 3. [DOI: 10.1002/14651858.CD007049.pub2]
67. Gurusamy KS, Nagendran M, Guerrini GP, Toon C, Zinnuroglu M, Davidson BR. Intraperitoneal local anaesthetic instillation versus no intraperitoneal local anaesthetic instillation for laparoscopic cholecystectomy. Cochrane Database of Systematic Reviews 2014, Issue 3. [DOI: 10.1002/14651858.CD007337.pub3]
68. Gurusamy KS, Vaughan J, Rossi M, Davidson BR. Fewer-than-four ports versus four ports for laparoscopic cholecystectomy. Cochrane Database of Systematic Reviews 2014, Issue 2. [DOI: 10.1002/14651858.CD007109.pub2]
69. Halldestam I, Enell EL, Kullman E, Borch K. Development of symptoms and complications in individuals with asymptomatic gallstones. British Journal of Surgery 2004;91(6):734-8.
70. Henny CP, Hofland J. Laparoscopic surgery: pitfalls due to anesthesia, positioning, and pneumoperitoneum. Surgical Endoscopy 2005;19(9):1163-71.
71. HESonline . Hospital Episode Statistics. Main procedures and interventions: 3 character. http://www.hesonline.nhs.uk/Ease/servlet/ContentServer?siteID=1937&categoryID=205 2011 (accessed on 7 August 2013).
72. Higgins JPT, Thompson SG. Quantifying heterogeneity in a meta-analysis. Statistics in Medicine 2002;21(11):1539-58.
73. Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Colloboration, 2011. www.cochrane-handbook.org.
74. International Conference on Harmonisation Expert Working Group. International conference on harmonisation of technical requirements for registration of pharmaceuticals for human use. ICH harmonised tripartite guideline. Guideline for good clinical practice CFR & ICH Guidelines. Vol. 1, PA 19063-2043, USA: Barnett International/PAREXEL, 1997.
75. Junghans T, Bohm B, Grundel K, Schwenk W. Effects of pneumoperitoneum with carbon dioxide, argon, or helium on hemodynamic and respiratory function. Archives of Surgery 1997;132(3):272-8.
76. Kjaergard LL, Villumsen J, Gluud C. Reported methodologic quality and discrepancies between large and small randomized trials in meta-analyses. Annals of Internal Medicine 2001;135(11):982-9.
77. Lundh A, Sismondo S, Lexchin J, Busuioc OA, Bero L. Industry sponsorship and research outcome. Cochrane Database of Systematic Reviews 2012, Issue 12. [DOI: 10.1002/14651858.MR000033.pub2]
78. Macaskill P, Walter SD, Irwig L. A comparison of methods to detect publication bias in meta-analysis. Statistics in Medicine 2001;20(4):641-54.
79. Mertens zur Borg IR, Lim A, Verbrugge SJ, Jzermans IJ, Klein J. Effect of intraabdominal pressure elevation and positioning on hemodynamic responses during carbon dioxide pneumoperitoneum for laparoscopic donor nephrectomy: a prospective controlled clinical study. Surgical Endoscopy 2004;18(6):919-23.
80. Moher D, Pham B, Jones A, Cook DJ, Jadad AR, Moher M, et al.Does quality of reports of randomised trials affect estimates of intervention efficacy reported in meta-analyses?. Lancet 1998;352(9128):609-13.
81. Neudecker J, Sauerland S, Neugebauer E, Bergamaschi R, Bonjer HJ, Cuschieri A, et al.The European Association for Endoscopic Surgery clinical practice guideline on the pneumoperitoneum for laparoscopic surgery. Surgical Endoscopy 2002;16(7):1121-43.
82. Neuhaus SJ, Watson DI, Ellis T, Lafullarde T, Jamieson GG, Russell WJ. Metabolic and immunologic consequences of laparoscopy with helium or carbon dioxide insufflation: a randomized clinical study. Australian and New Zealand Journal of Surgery 2001;71(8):447-52.
83. Newell DJ. Intention-to-treat analysis: implications for quantitative and qualitative research. International Journal of Epidemiology 1992;21(5):837-41.
84. NIH . NIH consensus statement on gallstones and laparoscopic cholecystectomy. http://consensus.nih.gov/1992/1992GallstonesLaparoscopy090html.htm 1992 (accessed 7 August 2013).
85. The Nordic Cochrane Centre, The Cochrane Collaboration. Review Manager (RevMan). 5.2. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2012.
86. Royle P, Milne R. Literature searching for randomized controlled trials used in Cochrane reviews: rapid versus exhaustive searches. International Journal of Technology Assessment in Health Care 2003;19(4):591-603.
87. Russell RC. General surgery: biliary surgery. BMJ (Clinical Research Ed.) 1993;307(6914):1266-9.
88. Savović J, Jones HE, Altman DG, Harris RJ, Juni P, Pildal J, et al.Influence of reported study design characteristics on intervention effect estimates from randomized, controlled trials. Annals of Internal Medicine 2012;157(6):429-38.
89. Savović J, Jones HE, Altman DG, Harris RJ, Jüni P, Pildal J, et al.Influence of reported study design characteristics on intervention effect estimates from randomized, controlled trials. Health Technology Assessment 2012;16(35):1-82.
90. Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA 1995;273(5):408-12.
91. Strasberg SM, Clavien PA. Overview of therapeutic modalities for the treatment of gallstone diseases. American Journal of Surgery 1993;165(4):420-6.
92. Thorlund K, Devereaux PJ, Wetterslev J, Guyatt G, Ioannidis JP, Thabane L, et al.Can trial sequential monitoring boundaries reduce spurious inferences from meta-analyses. International Journal of Epidemiology 2009;38(1):276-86.
93. Thorlund K, Anema A, Mills E. Interpreting meta-analysis according to the adequacy of sample size. An example using isoniazid chemoprophylaxis for tuberculosis in purified protein derivative negative HIV-infected individuals. Clinical Epidemiology 2010;2:57-66.
94. Thorlund K, Engstrøm J, Wetterslev J, Brok J, Imberger G, Gluud C. User manual for Trial Sequential Analysis (TSA). http://ctu.dk/tsa/files/tsa_manual.pdf 2011 (accessed 7 August 2013).
95. Wetterslev J, Thorlund K, Brok J, Gluud C. Trial sequential analysis may establish when firm evidence is reached in cumulative meta-analysis. Journal of Clinical Epidemiology 2008;61(1):64-75.
96. Wetterslev J, Thorlund K, Brok J, Gluud C. Estimating required information size by quantifying diversity in random-effects model meta-analyses. BMC Medical Research Methodology 2009;9:86.
97. Wood L, Egger M, Gluud LL, Schulz KF, Jüni P, Altman GD, et al.Empirical evidence of bias in treatment effect estimates in controlled trials with different interventions and outcomes: meta-epidemiological study. BMJ (Clinical Research Ed.) 2008;336:601-5.
98. Gurusamy KS, Samraj K, Davidson BR. Low pressure versus standard pressure pneumoperitoneum in laparoscopic cholecystectomy. Cochrane Database of Systematic Reviews 2009, Issue 2. [DOI: 10.1002/14651858.CD006930.pub2]