Comparison of carbon dioxide and room air pneumoperitoneum for day-case diagnostic laparoscopy

Gases for establishing pneumoperitoneum during laparoscopic abdominal surgery

BACKGROUND

This is the second update of a Cochrane Review first published in 2013 and last updated in 2017. Laparoscopic surgery is now widely performed to treat various abdominal diseases. Currently, carbon dioxide is the most frequently used gas for insufflation of the abdominal cavity (pneumoperitoneum). Although carbon dioxide meets most of the requirements for pneumoperitoneum, the absorption of carbon dioxide may be associated with adverse events. Therefore, other gases have been introduced as alternatives to carbon dioxide for establishing pneumoperitoneum.

OBJECTIVES

To assess the safety, benefits, and harms of different gases (e.g. carbon dioxide, helium, argon, nitrogen, nitrous oxide, and room air) used for establishing pneumoperitoneum in participants undergoing laparoscopic abdominal or gynaecological pelvic surgery.

SEARCH METHODS

We searched CENTRAL, Ovid MEDLINE, Ovid Embase, four other databases, and three trials registers on 15 October 2021 together with reference checking, citation searching, and contact with study authors to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different gases for establishing pneumoperitoneum in participants (irrespective of age, sex, or race) undergoing laparoscopic abdominal or gynaecological pelvic surgery under general anaesthesia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 10 RCTs, randomising 583 participants, comparing different gases for establishing pneumoperitoneum: nitrous oxide (four trials), helium (five trials), or room air (one trial) was compared to carbon dioxide. All the RCTs were single-centre studies. Four RCTs were conducted in the USA; two in Australia; one in China; one in Finland; one in Iran; and one in the Netherlands. The mean age of the participants ranged from 27.6 years to 49.0 years. Four trials randomised participants to nitrous oxide pneumoperitoneum (132 participants) or carbon dioxide pneumoperitoneum (128 participants). None of the trials was at low risk of bias. The evidence is very uncertain about the effects of nitrous oxide pneumoperitoneum compared to carbon dioxide pneumoperitoneum on cardiopulmonary complications (Peto odds ratio (OR) 2.62, 95% CI 0.78 to 8.85; 3 studies, 204 participants; very low-certainty evidence), or surgical morbidity (Peto OR 1.01, 95% CI 0.14 to 7.31; 3 studies, 207 participants; very low-certainty evidence). There were no serious adverse events related to either nitrous oxide or carbon dioxide pneumoperitoneum (4 studies, 260 participants; very low-certainty evidence). Four trials randomised participants to helium pneumoperitoneum (69 participants) or carbon dioxide pneumoperitoneum (75 participants) and one trial involving 33 participants did not state the number of participants in each group. None of the trials was at low risk of bias. The evidence is very uncertain about the effects of helium pneumoperitoneum compared to carbon dioxide pneumoperitoneum on cardiopulmonary complications (Peto OR 1.66, 95% CI 0.28 to 9.72; 3 studies, 128 participants; very low-certainty evidence), or surgical morbidity (5 studies, 177 participants; very low-certainty evidence). There were three serious adverse events (subcutaneous emphysema) related to helium pneumoperitoneum (3 studies, 128 participants; very low-certainty evidence). One trial randomised participants to room air pneumoperitoneum (70 participants) or carbon dioxide pneumoperitoneum (76 participants). The trial was at high risk of bias. There were no cardiopulmonary complications, serious adverse events, or deaths observed related to either room air or carbon dioxide pneumoperitoneum.    AUTHORS' CONCLUSIONS: The evidence is very uncertain about the effects of nitrous oxide, helium, and room air pneumoperitoneum compared to carbon dioxide pneumoperitoneum on any of the primary outcomes, including cardiopulmonary complications, surgical morbidity, and serious adverse events. The safety of nitrous oxide, helium, and room air pneumoperitoneum has yet to be established, especially in people with high anaesthetic risk.

Successful laparoscope-assisted orchiectomy in three cryptorchid sheep

Three adult Corriedale cryptorchid sheep were subjected to laparoscope-assisted orchiectomy of the retained testicles. One (n = 2) or both (n = 1) the testicles were missing in their scrotal sac and inguinal regions. Ultrasonography was used to locate the retained testicles and their distance from the abdominal surface. The animals were restrained in dorsal recumbency and Trendlenburg posture under lumbosacral epidural anaesthesia using 2% lignocaine hydrochloride. Two laparoscopic ports were created in the caudal abdomen adjacent to the retained testicles. They were identified by their ovoid shape, white glistening surface (Tunica albuginea) and typical vasculature. Laparoscope-assisted exteriorization of the testicles after enlarging the ports, ligation of their blood supply and resection of the spermatic cord was performed successfully. The scrotal testes in two rams were then subjected to routine Burdizzoo castration. The laparoscopic port sites healed without complications and all the animals continued to do well subsequently. From this case report, it is concluded that in sheep the laparoscopy; a minimally invasive procedure can confirm abdominal retention of testicle/s and may also be used for their retrieval in a single sitting. Although total laparoscopic procedure is expected to reduce the incision size further but requires advanced laparoscopic instruments and expertise.

Interventions to reduce shoulder pain following gynaecological laparoscopic procedures

BACKGROUND

Laparoscopy is a common procedure used to diagnose and treat various gynaecological conditions. Shoulder-tip pain (STP) as a result of the laparoscopy occurs in up to 80% of women, with potential for significant morbidity, delayed discharge and readmission. Interventions at the time of gynaecological laparoscopy have been developed in an attempt to reduce the incidence and severity of STP.

OBJECTIVES

To determine the effectiveness and safety of methods for reducing the incidence and severity of shoulder-tip pain (STP) following gynaecological laparoscopy.

SEARCH METHODS

We searched the following databases: Cochrane Gynaecology and Fertility (CGF) Specialised Register, the Cochrane Central Register of Studies Online (CRSO), MEDLINE, Embase, PsycINFO and CINAHL from inception to 8 August 2018. We also searched the reference lists of relevant articles and registers of ongoing trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions used during or immediately after gynaecological laparoscopy to reduce the incidence or severity of STP.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Primary outcomes: incidence or severity of STP and adverse events of the interventions; secondary outcomes: analgesia usage, delay in discharge, readmission rates, quality-of-life scores and healthcare costs.

MAIN RESULTS

We included 32 studies (3284 women). Laparoscopic procedures in these studies varied from diagnostic procedures to complex operations. The quality of the evidence ranged from very low to moderate. The main limitations were risk of bias, imprecision and inconsistency.Specific technique versus "standard" technique for releasing the pneumoperitoneumUse of a specific technique of releasing the pneumoperitoneum (pulmonary recruitment manoeuvre, extended assisted ventilation or actively aspirating intra-abdominal gas) reduced the severity of STP at 24 hours (standardised mean difference (SMD) -0.66, 95% confidence interval (CI) -0.82 to -0.50; 5 RCTs; 670 participants; I² = 0%, low-quality evidence) and reduced analgesia usage (SMD -0.53, 95% CI -0.70 to -0.35; 4 RCTs; 570 participants; I² = 91%, low-quality evidence). There appeared to be little or no difference in the incidence of STP at 24 hours (odds ratio (OR) 0.87, 95% CI 0.41 to 1.82; 1 RCT; 118 participants; low-quality evidence).No adverse events occurred in the only study assessing this outcome.Fluid instillation versus no fluid instillationFluid instillation is probably associated with a reduction in STP incidence (OR 0.38, 95% CI 0.22 to 0.66; 2 RCTs; 220 participants; I² = 0%, moderate-quality evidence) and severity (mean difference (MD) (0 to 10 visual analogue scale (VAS) scale) -2.27, 95% CI -3.06 to -1.48; 2 RCTs; 220 participants; I² = 29%, moderate-quality evidence) at 24 hours, and may reduce analgesia usage (MD -12.02, 95% CI -23.97 to -0.06; 2 RCTs; 205 participants, low-quality evidence).No study measured adverse events.Intraperitoneal drain versus no intraperitoneal drainUsing an intraperitoneal drain may reduce the incidence of STP at 24 hours (OR 0.30, 95% CI 0.20 to 0.46; 3 RCTs; 417 participants; I² = 90%, low-quality evidence) and may reduce analgesia use within 48 hours post-operatively (SMD -1.84, 95% CI -2.14 to -1.54; 2 RCTs; 253 participants; I² = 90%). We are uncertain whether it reduces the severity of STP at 24 hours, as the evidence was very low quality (MD (0 to 10 VAS scale) -1.85, 95% CI -2.15 to -1.55; 3 RCTs; 320 participants; I² = 70%).No study measured adverse events.Subdiaphragmatic intraperitoneal local anaesthetic versus control (no fluid instillation, normal saline or Ringer's lactate)There is probably little or no difference between the groups in incidence of STP (OR 0.72, 95% CI 0.42 to 1.23; 4 RCTs; 336 participants; I² = 0%; moderate-quality evidence) and there may be no difference in STP severity (MD -1.13, 95% CI -2.52 to 0.26; 1 RCT; 50 participants; low-quality evidence), both measured at 24 hours. However, the intervention may reduce post-operative analgesia use (SMD-0.57, 95% CI -0.94 to -0.21; 2 RCTs; 129 participants; I² = 51%, low-quality evidence).No adverse events occurred in any study.Local anaesthetic into peritoneal cavity (not subdiaphragmatic) versus normal salineLocal anaesthetic into the peritoneal cavity may reduce the incidence of STP at 4 to 8 hours post-operatively (OR 0.23, 95% CI 0.06 to 0.93; 2 RCTs; 157 participants; I² = 56%; low-quality evidence). Our other outcomes of interest were not assessed.Warmed, or warmed and humidified CO₂ versus unwarmed and unhumidified CO₂There may be no difference between these interventions in incidence of STP at 24 to 48 hours (OR 0.81 95% CI 0.45 to 1.49; 2 RCTs; 194 participants; I² = 12%; low-quality evidence) or in analgesia usage within 48 hours (MD -4.97 mg morphine, 95% CI -11.25 to 1.31; 1 RCT; 95 participants; low-quality evidence); there is probably little or no difference in STP severity at 24 hours (MD (0 to 10 VAS scale) 0.11, 95% CI -0.75 to 0.97; 2 RCTs; 157 participants; I² = 50%; moderate-quality evidence).No study measured adverse events.Gasless laparoscopy versus CO₂ insufflationGasless laparoscopy may be associated with increased severity of STP within 72 hours post-operatively when compared with standard treatment (MD 3.8 (0 to 30 VAS scale), 95% CI 0.76 to 6.84; 1 RCT; 54 participants, low-quality evidence), and there may be no difference in the risk of adverse events (OR 2.56, 95% CI 0.25 to 26.28; 1 RCT; 54 participants; low-quality evidence).No study measured the incidence of STP.

AUTHORS' CONCLUSIONS

There is low to moderate-quality evidence that the following interventions are associated with a reduction in the incidence or severity, or both, of STP, or a reduction in analgesia requirements for women undergoing gynaecological laparoscopy: a specific technique for releasing the pneumoperitoneum; intraperitoneal fluid instillation; an intraperitoneal drain; and local anaesthetic applied to the peritoneal cavity (not subdiaphragmatic).There is low to moderate-quality evidence that subdiaphragmatic intraperitoneal local anaesthetic and warmed and humidified insufflating gas may not make a difference to the incidence or severity of STP.There is low-quality evidence that gasless laparoscopy may increase the severity of STP, compared with standard treatment.Few studies reported data on adverse events. Some potentially useful interventions have not been studied by RCTs of gynaecological laparoscopy.

Radiofrequency Ablation of T1a Renal Cell Carcinomas within Renal Transplant Allografts: Oncologic Outcomes and Graft Viability

PURPOSE

To evaluate oncologic outcomes and graft viability after percutaneous radiofrequency (RF) ablation of renal cell carcinoma (RCC) developing within renal transplant allografts.

MATERIALS AND METHODS

A single-institution, retrospective study reviewed all patients treated with RF ablation for RCC between February 2004 and May 2016. Ten patients were identified (age 49.6 y ± 12.6; 9 men, 1 woman) with 12 biopsy-confirmed RCC tumors within the allograft (all T1a, mean diameter 2.0 cm ± 0.7). Mean time from transplant to RCC diagnosis was 13.2 years ± 6.3. RF ablation was performed on an outpatient basis using conscious sedation. Procedural efficacy, complications, oncologic outcomes, and allograft function were evaluated. Statistical analysis with t tests and Pearson correlation compared allograft function before and after RF ablation and impact of proportional ablation size to allograft volume on function after ablation.

RESULTS

Technical success rate and primary technique efficacy were 100% (12/12). No local or distant RCC progression was seen at mean follow-up of 54.3 months ± 38.7 (range, 9-136 months). Graft failure requiring hemodialysis or repeat transplantation occurred in 3 patients (26, 354, and 750 d after RF ablation), all of whom had glomerular filtration rate (GFR) < 30 mL/min/1.73 m² before ablation. For all patients, mean GFR 6 months after RF ablation (35.8 mL/min/1.73 m² ± 17.7) was not significantly different (P = .8) from preprocedure GFR (36.2 mL/min/1.73 m² ± 14.3). Proportional volume of allograft that was ablated did not correlate with immediate or long-term GFR changes. One patient died of unrelated comorbidities 52 months after ablation. No major complications occurred.

CONCLUSIONS

RF ablation of renal allograft RCC provided effective oncologic control without adverse impact on graft viability.

Gases for establishing pneumoperitoneum during laparoscopic abdominal surgery

BACKGROUND

This is an update of the review published in 2013.Laparoscopic surgery is now widely performed to treat various abdominal diseases. Currently, carbon dioxide is the most frequently used gas for insufflation of the abdominal cavity (pneumoperitoneum). Although carbon dioxide meets most of the requirements for pneumoperitoneum, the absorption of carbon dioxide may be associated with adverse events. People with high anaesthetic risk are more likely to experience cardiopulmonary complications and adverse events, for example hypercapnia and acidosis, which has to be avoided by hyperventilation. Therefore, other gases have been introduced as alternatives to carbon dioxide for establishing pneumoperitoneum.

OBJECTIVES

To assess the safety, benefits, and harms of different gases (i.e. carbon dioxide, helium, argon, nitrogen, nitrous oxide, and room air) used for establishing pneumoperitoneum in participants undergoing laparoscopic general abdominal or gynaecological pelvic surgery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 9), Ovid MEDLINE (1950 to September 2016), Ovid Embase (1974 to September 2016), Science Citation Index Expanded (1970 to September 2016), Chinese Biomedical Literature Database (CBM) (1978 to September 2016), ClinicalTrials.gov (September 2016), and World Health Organization International Clinical Trials Registry Platform (September 2016).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different gases for establishing pneumoperitoneum in participants (irrespective of age, sex, or race) undergoing laparoscopic abdominal or gynaecological pelvic surgery under general anaesthesia.

DATA COLLECTION AND ANALYSIS

Two review authors identified the trials for inclusion, collected the data, and assessed the risk of bias independently. We performed the meta-analyses using Review Manager 5. We calculated risk ratio (RR) for dichotomous outcomes (or Peto odds ratio for very rare outcomes), and mean difference (MD) or standardised mean difference (SMD) for continuous outcomes with 95% confidence intervals (CI). We used GRADE to rate the quality of evidence, MAIN RESULTS: We included nine RCTs, randomising 519 participants, comparing different gases for establishing pneumoperitoneum: nitrous oxide (three trials), helium (five trials), or room air (one trial) was compared to carbon dioxide. Three trials randomised participants to nitrous oxide pneumoperitoneum (100 participants) or carbon dioxide pneumoperitoneum (96 participants). None of the trials was at low risk of bias. There was insufficient evidence to determine the effects of nitrous oxide and carbon dioxide on cardiopulmonary complications (RR 2.00, 95% CI 0.38 to 10.43; two studies; 140 participants; very low quality of evidence), or surgical morbidity (RR 1.01, 95% CI 0.18 to 5.71; two studies; 143 participants; very low quality of evidence). There were no serious adverse events related to either nitrous oxide or carbon dioxide pneumoperitoneum (three studies; 196 participants; very low quality of evidence). We could not combine data from two trials (140 participants) which individually showed lower pain scores (a difference of about one visual analogue score on a scale of 1 to 10 with lower numbers indicating less pain) with nitrous oxide pneumoperitoneum at various time points on the first postoperative day, and this was rated asvery low quality .Four trials randomised participants to helium pneumoperitoneum (69 participants) or carbon dioxide pneumoperitoneum (75 participants) and one trial involving 33 participants did not state the number of participants in each group. None of the trials was at low risk of bias. There was insufficient evidence to determine the effects of helium or carbon dioxide on cardiopulmonary complications (RR 1.46, 95% CI 0.35 to 6.12; three studies; 128 participants; very low quality of evidence) or pain scores (visual analogue score on a scale of 1 to 10 with lower numbers indicating less pain; MD 0.49 cm, 95% CI -0.28 to 1.26; two studies; 108 participants; very low quality of evidence). There were three serious adverse events (subcutaneous emphysema) related to helium pneumoperitoneum (three studies; 128 participants; very low quality of evidence).One trial randomised participants to room air pneumoperitoneum (70 participants) or carbon dioxide pneumoperitoneum (76 participants). The trial was at unclear risk of bias. There were no cardiopulmonary complications or serious adverse events observed related to either room air or carbon dioxide pneumoperitoneum (both outcomes very low quality of evidence). The evidence of lower hospital costs and reduced pain during the first postoperative day with room air pneumoperitoneum compared with carbon dioxide pneumoperitoneum (a difference of about one visual analogue score on a scale of 1 to 10 with lower numbers indicating less pain, was rated as very low quality of evidence.

AUTHORS' CONCLUSIONS

The quality of the current evidence is very low. The effects of nitrous oxide and helium pneumoperitoneum compared with carbon dioxide pneumoperitoneum are uncertain. Evidence from one trial of small sample size suggests that room air pneumoperitoneum may decrease hospital costs in people undergoing laparoscopic abdominal surgery. The safety of nitrous oxide, helium, and room air pneumoperitoneum has yet to be established.Further trials on this topic are needed, and should compare various gases (i.e. nitrous oxide, helium, argon, nitrogen, and room air) with carbon dioxide under standard pressure pneumoperitoneum with cold gas insufflation for people with high anaesthetic risk. Future trials should include outcomes such as complications, serious adverse events, quality of life, and pain.

Laparoscopy Using Room Air Insufflation in a Rural African Jungle Hospital: The Bongolo Hospital Experience, January 2006 to December 2013

INTRODUCTION

Carbon dioxide is the standard insufflation gas for laparoscopy. However, in many areas of the world, bottled carbon dioxide is not available. Laparoscopy offers advantages over open surgery and has been practiced using filtered room air insufflation since 2006 at Bongolo Hospital in Gabon, Africa.

OBJECTIVE

Our primary goal was to evaluate the safety of room air insufflation related to intraoperative and postoperative complications. Our secondary aim was to review the types of cases performed laparoscopically at our institution.

METHODS

This retrospective review evaluates laparoscopic cases performed at Bongolo Hospital between January 2006 and December 2013. Demographic and perioperative information for patients undergoing laparoscopic procedures was collected. Insufflation was achieved using a standard, oil-free air compressor using filtered air and a standard insufflation regulator.

RESULTS

A total of 368 laparoscopic procedures were identified within the time period. The majority of cases were gynecologic (43%). There was a 2% (8/368) complication rate with one perioperative death. The 2 complications related to insufflation were episodes of hypotension responsive to standard corrective measures. No intracorporeal combustion events were observed in any cases in which the use of diathermy and room air insufflation were combined. The other complications and the death were unrelated to the use of insufflation with air.

CONCLUSION

Insufflation complications with room air occurred in our study. However, the complications related to insufflation with room air in our study were no different than those described in the literature using carbon dioxide. As room air is less costly than carbon dioxide and readily available, confirming the safety of room air insufflation in prospective studies is warranted. Room air appears to be safe for establishing and maintaining pneumoperitoneum, making laparoscopic surgery more accessible to patients in low-resource settings.

Association between intraabdominal pressure during gynaecologic laparoscopy and postoperative pain

PURPOSE

Laparoscopy is nowadays a well-established surgical method and plays a main role in an ever-increasing range of indications in gynaecology. High-quality studies of surgical techniques are necessary to improve the quality of patient care. The present study aims at evaluating postoperative pain after gynaecological laparoscopy depending on the intraoperative CO₂ pressure.

METHODS

In a prospective, monocentric, randomized single-blind study at the Department of Gynaecology and Obstetrics at the Hannover Medical School, we include patients scheduled for different laparoscopic procedures. Randomization of the intraoperative CO₂ pressure was carried out in six groups. Pain was assessed the day after surgery by the blinded nurse using a visual analogue scale.

RESULTS

550 patients were included in the period from May 2013 to January 2016. The analysis of the per protocol population PPP (n = 360) showed no statistically significant difference between the six intervention groups with regard to mean postoperative pain perception. In direct comparison between two groups, an intraoperative CO₂ pressure of 15 mmHg was associated with a significant higher pain score than a pressure of 12 mmHg. The difference was 7.46 mm on a 10 cm VAS.

CONCLUSIONS

The results of our study indicate that a CO₂ pressure of 12 versus 15 mmHg can be advantageous. However, the clinical relevance remains unclear due to the low difference in pain. The additional benefit of an even lower pressure of 10 or 8 mmHg cannot be reliably assessed; we found signs of poor visibility conditions in these low pressure groups.

Laparoscopy in trauma: An overview of complications and related topics

The introduction of laparoscopy has provided trauma surgeons with a valuable diagnostic and, at times, therapeutic option. The minimally invasive nature of laparoscopic surgery, combined with potentially quicker postoperative recovery, simplified wound care, as well as a growing number of viable intraoperative therapeutic modalities, presents an attractive alternative for many traumatologists when managing hemodynamically stable patients with selected penetrating and blunt traumatic abdominal injuries. At the same time, laparoscopy has its own unique complication profile. This article provides an overview of potential complications associated with diagnostic and therapeutic laparoscopy in trauma, focusing on practical aspects of identification and management of laparoscopy-related adverse events.

Endoscopic gastrojejunostomy with a natural orifice transluminal endoscopic surgery technique

AIM: To determine the technical feasibility and safety of an endoscopic gastrojejunostomy with a pure natural orifice transluminal endoscopic surgery (NOTES) technique using a T-anchoring device in a porcine survival model.

METHODS: An endoscopic gastrojejunostomy with a pure NOTES technique using a T-anchoring device was performed on 10 healthy female minipigs weighing approximately 40 kg each under general anesthesia. All procedures were performed with a transgastric approach using a 2-channel therapeutic endoscope.

RESULTS: The transgastric gastrojejunostomy was technically successful in all cases. A total of four to six stitched pairs of a T-anchoring device were used to secure the anastomosis. The median time required to enter the peritoneal cavity and pull the small bowel into the stomach was 34 min (range: 19-41 min); the median time required to suture the anastomosis was 67 min (range: 44-78 min). An obstruction of the efferent limb occurred in one case, and a rupture of the anastomosis site occurred in another case. As a result, the functional success rate was 80% (8/10). Small bowel adhesion to the stomach and liver occurred in one case, but the anastomosis was intact without leakage or obstruction.

CONCLUSION: A transgastric gastrojejunostomy with a T-anchoring device may be safe and technically feasible. A T-anchoring device may provide a simple and effective endoscopic suturing method.

A review of equine laparoscopy

Minimally invasive surgery in the human was first identified in mid 900's. The procedure as is more commonly practiced now was first reported in 1912. There have been many advances and new techniques developed in the past 100 years. Equine laparoscopy, was first reported in the 1970's, and similarly has undergone much transformation in the last 40 years. It is now considered the standard of care in many surgical techniques such as cryptorchidectomy, ovariectomy, nephrosplenic space ablation, standing abdominal exploratory, and many other reproductive surgeries. This manuscript describes the history of minimally invasive surgery, and highlights many of the techniques that are currently performed in equine surgery. Special attention is given to instrumentation, ligating techniques, and the surgical principles of equine minimally invasive surgery.

Impact of pressure and gas type on adhesion formation and biomaterial integration in laparoscopy

BACKGROUND

Laparoscopic mesh repair of inguinal and incisional hernias has been widely adopted. Nevertheless, knowledge about the impact of pneumoperitoneum on mesh integration is rare. The present study investigates pressure and gas-dependent effects of pneumoperitoneum on adhesion formation and biomaterial integration in a standardized animal model.

METHODS

Laparoscopic intraperitoneal onlay mesh implantation (IPOM) was performed in 32 female chinchilla rabbits using CO(2) or helium for pneumoperitoneum. Intra-abdominal pressures were 3 or 6 mmHg. Animals were killed after 21 days, and the abdominal wall was explanted for subsequent histopathological examinations. Adhesions were assessed qualitatively with a scoring system, and the adhesion surface was analyzed semiquantitatively by planimetry. Infiltration of macrophages (CD68), expression of matrix metalloproteinase 13 (MMP-13), and cell proliferation (Ki67) were analyzed at the mesh to host interface by immunohistochemistry. The collagen type I/III ratio was analyzed by cross-polarization microscopy to determine the quality of mesh integration.

RESULTS

After 21 days, perifilamental infiltration with macrophages (CD68) and percentage of proliferating cells (Ki67) were highest after 6 mmHg of CO(2) pneumoperitoneum. The extent of adhesions, as well as the expression of MMP-13 and the collagen type I/III ratio, were similar between groups.

CONCLUSIONS

Our experiments showed no pressure or gas-dependent alterations of adhesion formation and only minor effects on biomaterial integration. Altogether, there is no evidence for a clinically negative effect of CO(2) pneumoperitoneum.

Regulation of gene expression by carbon dioxide

Carbon dioxide (CO(2)) is a physiological gas found at low levels in the atmosphere and produced in cells during the process of aerobic respiration. Consequently, the levels of CO(2) within tissues are usually significantly higher than those found externally. Shifts in tissue levels of CO(2) (leading to either hypercapnia or hypocapnia) are associated with a number of pathophysiological conditions in humans and can occur naturally in niche habitats such as those of burrowing animals. Clinical studies have indicated that such altered CO(2) levels can impact upon disease progression. Recent advances in our understanding of the biology of CO(2) has shown that like other physiological gases such as molecular oxygen (O(2)) and nitric oxide (NO), CO(2) levels can be sensed by cells resulting in the initiation of physiological and pathophysiological responses. Acute CO(2) sensing in neurons and peripheral and central chemoreceptors is important in rapidly activated responses including olfactory signalling, taste sensation and cardiorespiratory control. Furthermore, a role for CO(2) in the regulation of gene transcription has recently been identified with exposure of cells and model organisms to high CO(2) leading to suppression of genes involved in the regulation of innate immunity and inflammation. This latter, transcriptional regulatory role for CO(2), has been largely attributed to altered activity of the NF-B family of transcription factors. Here, we review our evolving understanding of how CO(2) impacts upon gene transcription.

Gasless balloon laparoscopy

BACKGROUND

The concept of balloon laparoscopy (B-LSC) pursues the simplification of conventional diagnostic laparoscopy (LSC). The pneumoperitoneum is replaced by a transparent balloon, which is positioned in front of the optical system. It shall be shown that with this arrangement diagnostic LSC can be performed outside of the operating room without requiring general anesthesia.

METHODS

An inflatable balloon was developed for a 30 degrees /3.5-mm rod lens. Intra-abdominally the balloon was expanded to a diameter of 30 mm by air insufflation, and B-LSC was performed. Twelve patients were examined in general anesthesia before laparoscopic surgery. Twelve patients were subjected to B-LSC fully awake or with sedation (midazolam or propofol/S-ketamine) as a "second-look" procedure by way of a flexible trocar (port) left in the abdominal wall at the end of previous operation. Eight patients have been first provided with a trocar under sedation (midazolam or propofol/S-ketamine) combined with local anesthesia, and B-LSC was performed before laparoscopic surgery.

RESULTS

On a scale of 1-5, the general impression was rated 1.9, the navigability to the different abdominal organs 2.5, the resolution 1.5, the stability of the system optic/trocar 2.1, the suitability of the balloon format 1.9, and the stability of the balloon against lateral shear forces 2.4. The degree of painfulness of the examination was rated 2.8, the tolerance of the port 1.4, and the degree of painfulness of trocar placement at 2.5. On a scale of 1 to 3, the strain of the abdominal musculature was rated 1.4 and the obstruction by adhesions 1.7.

DISCUSSION

B-LSC is technically practicable with good imaging qualities and without requiring pneumoperitoneum. It is tolerated in great extent under slight sedation and particularly well under deep sedation. The procedure is suitable for diagnostics of unclear abdominal conditions, as a second-look LSC and also as a staging LSC.

Carbon dioxide versus room air for natural orifice transluminal endoscopic surgery (NOTES) and comparison with standard laparoscopic pneumoperitoneum

BACKGROUND

Most studies investigating natural orifice transluminal endoscopic surgery (NOTES) have used room air, whereas carbon dioxide (CO(2)) is traditionally preferred for laparoscopic insufflation.

OBJECTIVE

Evaluation of CO(2) versus room air for NOTES and comparison with standard laparoscopic pneumoperitoneum.

DESIGN

Prospective experiments in an acute porcine model.

INTERVENTIONS

For transgastric peritoneoscopy, either CO(2) or room air were insufflated via the endoscope for a constant intraperitoneal pressure of 12 mm Hg in 16 pigs. Another 8 pigs received laparoscopic insufflation with CO(2). Identification of intra-abdominal organs during NOTES was documented. Additionally, standardized video recordings of peritoneoscopy were evaluated by an independent blinded observer. Complete cardiopulmonary status was assessed every 3 minutes.

MAIN OUTCOME MEASUREMENTS

Quality of transgastric peritoneoscopy and cardiopulmonary response.

RESULTS

In the NOTES room air group, significantly more target organs (18/64, 28%) were missed than in the NOTES CO(2) group (8/64, 13%; P = .028). However, blinded video analysis showed no difference between the groups. An increase in systemic vascular resistance index during pneumoperitoneum in the NOTES room air group was less pronounced than in the NOTES CO(2) group, almost reaching the level of significance (P = .050). With respect to hemodynamics, there were no significant differences between the NOTES CO(2) group and the laparoscopy CO(2) group.

LIMITATIONS

Nonsurvival animal experiments.

CONCLUSIONS

Pressure-controlled endoscopic insufflation of CO(2) for NOTES showed minor advantages compared with insufflation of room air regarding intra-abdominal visualization, but resulted in an increase in cardiac afterload. However, the cardiorespiratory responses during endoscopic insufflation of CO(2) were similar to the widely accepted standard laparoscopic CO(2) insufflation.

Improved abdominal wall wound healing by helium pneumoperitoneum

BACKGROUND

Despite widespread use of the endoscopic technique in the treatment of inguinal and incisional hernias, knowledge about its impact on abdominal wall wound healing is rare. Questions remain regarding the risk of port-site hernias and hernia recurrence. The current study investigated the gas-dependent effects of pneumoperitoneum on laparotomy wound healing.

METHODS

Laparotomy was performed in 54 male Sprague-Dawley rats. A carbon dioxide (n = 18) or helium (n = 18) pneumoperitoneum of 3 mmHg was maintained before and after laparotomy, with an overall duration of 30 min. The rats in the control group (n = 18) received no pneumoperitoneum. The animals were killed after 5 and 10 days, and the abdominal wall was explanted for subsequent histopathologic examinations of the laparotomy wound. The granuloma formation in hematoxylin and eosin-stained sections was analyzed. Infiltration of macrophages (CD68) and expression of matrix metalloproteinases (MMP-8 and MMP-13) were examined by immunohistochemistry. The collagen type 1 to type 3 ratio was investigated by cross-polarization microscopy after Sirius Red staining.

RESULTS

After 5 and 10 days, the percentages of CD68-positive cells, granuloma formation, and expression of MMP-8 did not differ between the groups. In contrast, after both 5 and 10 days, the expression of MMP-13 and the collagen 1 to 3 ratio were significantly higher after helium pneumoperitoneum than in the control animals.

CONCLUSION

The results suggest that helium pneumoperitoneum may ameliorate wound healing within the abdominal wall and could therefore represent a beneficial gas for endoscopic hernia repair.

Comparison of intraabdominal pressures using the gastroscope and laparoscope for transgastric surgery

BACKGROUND

The peroral transgastric endoscopic approach for intraabdominal procedures appears to be feasible, although multiple aspects of this approach remain unclear. This study aimed to measure intraperitoneal pressure in a porcine model during the peroral transgastric endoscopic approach, comparing an endoscopic on-demand insufflator/light source with a standard autoregulated laparoscopic insufflator.

METHODS

All experiments were performed with 50-kg female pigs under general anesthesia. A standard upper endoscope was advanced perorally through a gastric wall incision into the peritoneal cavity. The peritoneal cavity was insufflated with operating room air from an endoscopic light source/insufflator. Intraperitoneal pressure was measured by three routes: (1) through the endoscope biopsy channel, (2) through a 5-mm transabdominal laparoscopic port, and (3) through a 16-gauge Veress needle inserted into the peritoneal cavity through the anterior abdominal wall. The source of insufflation alternated between on-demand manual insufflation through the endoscopic light source/insufflator using room air and a standard autoregulated laparoscopic insufflator using carbon dioxide (CO(2)).

RESULTS

Six acute experiments were performed. Intraperitoneal pressure measurements showed good correlation regardless of measurement route and were independent of the type of insufflation gas, whether room air or CO(2). On-demand insufflation with the endoscopic light source/insufflator resulted in a wide variation in pressures (range, 4-32 mmHg; mean, 16.0 +/- 11.7). Intraabdominal pressures using a standard autoregulated laparoscopic insufflator demonstrated minimal fluctuation (range, 8-15 mmHg; mean, 11.0 +/- 2.2 mmHg) around a predetermined value.

CONCLUSION

Use of an on-demand unregulated endoscopic light source/insufflator for translumenal surgery can cause large variation in intraperitoneal pressures and intraabdominal hypertension, leading to the risk of hemodynamic and respiratory compromise. Safety may favor well-controlled intraabdominal pressures achieved with a standard autoregulated laparoscopic insufflator.