Introduction
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Identify ideal gas mixtures for establishing pneumoperitoneum in abdominal and gynaecological pelvic surgery with current animal and human studies already undertaken (and with results) up to the writing of this review.
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Synthesise results from both non-randomised experimental and randomised control trials (RCT).
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Identify the risk of adhesion formation with each gas mixture medium as the primary outcome.
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Identify other outcome variables that may be affected due to the use of CO2 and promote the field of research to identify other suitable gas mixtures for insufflation.
Materials and methods
Search strategy
Database | Search terms | Filters | Total searches |
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PUBMED | ((Pneumoperitoneum[Title]) or (Insufflation[Title]) or (laparo*) or (robot*)) and (("Mixed gas") or ("ideal gas") or (nitrogen) or ("Gas mixture")) | 523 | |
EMBASE | 1. (pneumoperitoneum or insufflation or laparo* or robot*).mp 2. ("mixed gas" or "ideal gas" or "gas mixture").mp 3. 1 and 2 | 95 (dupe with Medline | |
MEDLINE | 1. (pneumoperitoneum or insufflation or laparo* or robot*).mp 2. ("mixed gas" or "ideal gas" or "gas mixture").mp 3. 1 and 2 | 95 (dupe with embase) | |
Clinicaltrials.gov | Pneumoperitoneum OR insufflation OR robotic surgery | With results | 122 |
Eligibility criteria
Inclusion criteria | Exclusion criteria |
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Laparoscopic abdominal and gynaecological pelvic surgeries | Secondary sources such as reviews, newsletters, government, and legal information |
Insufflation at standard pressure (12mmg to 16 mmHg) | Novel single gas type studies, e.g., reactive oxygen scavengers |
Non-randomised studies and RCT studies | Trials utilising mixed gas mixtures with no obtainable results |
Studies utilising gas mixtures | Studies where no English translation was available |
Animal and human studies | |
CO2 insufflation as the comparison group | Intervention arms or experiments comparing the utilisation of air as an experimental gas mixture |
Study selection
Data extraction
Quality assessment of individual studies
Results
Author | Animal or human | Country | Study design | Gas mixture intervention and insufflation pressure (mmHg) | n | Outcome measure | Conclusions of the primary outcome | |
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[3] Wildbrett 2002 | Animal (Inbred BD IX rats) | Germany | Non-randomised intervention | Group 1: CO2 Group 2: CO2 + 20% O2 | 10 10 | 10 10 | Tissue oxygen partial pressure (mmHg) | CO2 insufflation caused a significant decrease in tissue oxygen partial pressure from 23 to 5 mmHg (p = 0.000). Insufflation with a gas mixture of 80% CO2 and 20% O2 resulted in no significant difference between the control and intervention (p = 0.494) |
[12] Elkelani 2004 | Animal (Female mice) | Belgium | Randomised control trial | Group 1: CO2 Group 2: CO2 + 3% O2 Group 3: CO2 + 6% O2 Group 4: CO2 + 9% O2 Group 5: CO2 + 12% O2 | 15 15 15 15 15 | 5 5 5 5 5 | Adhesion score Adhesion proportion | Adhesions decreased after the addition of 3% oxygen (P = 0.05). Compared to CO2 + 3% O2, adhesions increased with the addition of 6% (P = 0.05), 9% (P = 0.01) and 12% (P = 0.02) oxygen |
[13] Binda 2009 | Animal (Female BALB/c mice) | Belgium | Randomised control trial | Group 1: CO2 Group 2: CO2 + 3% O2 | 15 15 | 4 4 | Adhesion score Adhesion proportion | Adhesions were reduced by adding 3% oxygen to the pneumoperitoneum (P = 0.05) |
[14] Corona 2011 | Animal (Female BALB/c mice) | Belgium | Randomised control trial | Group 1: CO2 + 4% O2 Group 2: CO2 | 15 15 | 4 4 | Adhesion score Adhesion proportion (results unobtainable) Inflammation score | In comparison with the control group (group 1), both the total and proportion of adhesions increased when a pure CO2 pneumoperitoneum was used (group 2; P = 0.007 and P = 0.0053, respectively) |
[15] Corona 2013 | Animal (Female BALB/c mice) | Belgium | Randomised control trial | Group 1: CO2 Group 2: CO2 + 5% N2O Group 3: CO2 + 10% N2O Group 4: CO2 + 25% N2O Group 5: CO2 + 50% N2O | 15 15 15 15 15 | 5 5 5 5 5 | Adhesion proportion Adhesion score (results unobtainable) | Varying percentages of N2O decreased the total and proportion of adhesions in all groups (P = 0.0001 and P = 0.0001, respectively). Adhesion formation between varying N2O percentages were not significantly different |
[16] Binda 2014 | Animal (Female BALB/cJRj mice) | Belgium | Randomised control trial | Group 1: CO2 Group 2: CO2 + 10% N2Oa Group 3: CO2 + 10% N2O + 4% O2a | 15 15 15 | 6 6 6 | Total tumours (1 week after tumour implantation in mice before intervention) | Intermediary steps failed to reach significance; that is CO2 + 10% N2O (1 vs 2), and CO2 + 10% of N2O + 4% of O2 (1 vs 3) |
[17] Binda 2021 | Animal (Female BALB/cJRj mice) | Belgium | Randomised control trial | Group 1: no intervention Group 2: CO2 Group 3: CO2 + 4% O2 | NA 15 15 | 8 8 8 | The effect on peritoneum morphology was assessed by scanning electron microscopy (SEM) | In samples taken 24 h after surgery, an increased cell retraction (p = 0.005), and changes in the total score (p = 0.03) were observed in the group 60 min of hypoxia with humidified CO2. The effect of adding O2 on mesothelial morphology did not reach significance |
[18] Koninckx 2013 | Human Female | Belgium | Randomised control trial | Group 1: CO2 Group 2: CO2 + 10% N2O + 4% O2a | 15 15 | 11 16 | Adhesion score VAS score | In the control group, a significantly high number of adhesions were found in all women. 1 filmy adhesion was found in 4 women of the full conditioning group; 12/16 were adhesion free. (P = 0.0005) |
[19] Verguts 2015 | Human Female | Belgium | Randomised control trial | Group 1: CO2 + Ringer’s lactate Group 2: CO2 + Icodextrin 4% Group 3: CO2 + 10% N2O + 4% O2 + Ringer’s lactatea Group 4: CO2 + 10% N2O + 4% O2 + Icodextrin 4%a | 15 15 15 15 | 5 5 5 5 | Resorption rates of fluids used in the prevention of adhesion after laparoscopic surgery | Group 3 showed a decreased resorption rate of Ringer’s lactate after 24, 48, and 72 h (P = 0.03, 0.009, and NS vs group 1), respectively. Group 4 did not affect the resorption rate of Icodextrin (NS vs group 2) |
20 Storme 2016 | Human Female | Belgium | Randomised control trial | Group 1: CO2 Group 2: CO2 + 10% N2O + 4% O2a | 15 15 | 7 7 | Adhesion score VAS score | A significantly high number of adhesions were found in all control patients. In the limited conditioning group, filmy adhesions were found in 4/7 women, while the remainder were adhesion free. Discontinuation of the surgeon, resulted in only 14/40 patients receiving surgery resulting in a reduction of power (P = 0.2040) |