Systematic review of oxidative stress associated with pneumoperitoneum

Underneath Images and Robots, Looking Deeper into the Pneumoperitoneum: A Narrative Review

Laparoscopy offers numerous advantages over open procedures, minimizing trauma, reducing pain, accelerating recovery, and shortening hospital stays. Despite other technical advancements, pneumoperitoneum insufflation has received little attention, barely evolving since its inception. We explore the impact of pneumoperitoneum on patient outcomes and advocate for a minimally invasive approach that prioritizes peritoneal homeostasis. The nonlinear relationship between intra-abdominal pressure (IAP) and intra-abdominal volume (IAV) is discussed, emphasizing IAP titration to balance physiological effects and surgical workspace. Maintaining IAP below 10 mmHg is generally recommended, but factors such as patient positioning and surgical complexity must be considered. The depth of neuromuscular blockade (NMB) is explored as another variable affecting laparoscopic conditions. While deep NMB appears favorable for surgical stillness, achieving a balance between IAP and NMB depth is crucial. Temperature and humidity management during pneumoperitoneum are crucial for patient safety and optical field quality. Despite the debate over the significance of temperature drop, humidification and the warming of insufflated gas offer benefits in peritoneal homeostasis and visual clarity. In conclusion, there is potential for a paradigm shift in pneumoperitoneum management, with dynamic IAP adjustments and careful control of insufflated gas temperature and humidity to preserve peritoneal homeostasis and improve patient outcomes in minimally invasive surgery.

What is the ideal preconditioning time to reduce laparoscopic-induced oxidative stress?

Introduction

Ischaemic preconditioning is the most effective method for the prevention of ischaemic-reperfusion injury; however, no study has examined the question of the ideal time for ischaemic preconditioning.

Patients and Methods

The patients were divided into five groups, each group including of 20 patients. The precondition was applied as 1, 5, 10 and 15 min in Groups I, II, III and IV and Group V was the control group. Repeated blood samples were taken to measure the total antioxidant status (TAS), total oxidant status and oxidative stress index (OSI) values, just before insufflation, at the end of the operation and at 6 and 24 h of the post-operative period.

Results

A significant difference was observed between the TAS values at the end of the operation and at the sixth post-operative time of the four groups (P = 0.001, 0.000, 0.001, 0.019 and 0.033, respectively). Furthermore, a significant difference was observed between TAS values at the post-operative 24th h of Group III and Group V, and also a significant difference was observed between the OSI values at the post-operative 6th h of Groups III and V.

Conclusion

The low OSI and TAS values may interpret as a low degree of oxidative damage. The OSI values at the post-operative 6 h of Groups I and II were lower than those of other groups. We accept this result as low oxidative damage.

Dayak Onions (Eleutherine americana L Merr) Reduced Mesothelial Cell Detachment After Laparoscopy in Rats

Background: Laparoscopy induces changes and detachment of mesothelial structure. Studies on the prevention of mesothelial cell detachment are rarely found. The Dayak tribe uses the Dayak onion (Eleutherine americana L. Merr) as a wound-healing agent due to its anti-inflammatory and antioxidant activities. This study aimed to prove the anti-inflammatory and antioxidant activities of Dayak onions in preventing mesothelial cell damage after laparoscopy. Materials and methods: Thirty male Sprague-Dawley rats were classified into five groups (n = 6 per group), namely: (a) control, (b) Mediclore, (c) Dayak onion, 30-, (d) 60-, and (e) 90 mg/kg body weight, respectively. The transforming growth factor-beta (TGF-β) and total oxidant status in the peritoneal fluid were determined 24 hours after laparoscopy. Histopathological analysis of mesothelial cell numbers and the protein Zone Occludin-1 (ZO-1) expression in the peritoneum, small intestines, greater omentum, and liver were performed 7 days after the procedure. An in-silico study was conducted to analyze the anti-inflammatory effects of the components of Dayak onions. Results: The in-silico study showed that one of the Dayak onion active compounds, eleutherine, had a potential anti-inflammatory effect and acted as a modulator of TGF-β. Following Dayak onion administration, the TGF- level, the number of mesothelial cell detachments, and ZO-1 expression were all significantly reduced (p<0.05), whereas the total oxidant status (TOS) level was not (p>0.05). Conclusions: Our study showed that Dayak onion administration reduced TGF-β level, number of mesothelial cell detachment, and ZO-1 expression following laparoscopy.

Deep Neuromuscular Blockade Combined with Low Pneumoperitoneum Pressure for Nociceptive Recovery After Major Laparoscopic Gastrointestinal Surgery: Study Protocol for a Randomized Controlled Trial

Purpose

Patients undergoing major laparoscopic surgery often experience significant pain and postoperative nausea and vomiting (PONV). Deep neuromuscular block (NMB) improves surgical conditions and facilitates the application of low intra-abdominal pressure (IAP), which may be beneficial for these patients. This study is designed to determine the effects of deep NMB combined with low IAP, as compared to moderate NMB combined with standard IAP, on patients' nociceptive recovery after major laparoscopic gastrointestinal surgery.

Study Design and Methods

This single-center randomized controlled trial will include 220 patients scheduled for major laparoscopic gastrointestinal surgery (lasts for ≥ 90 minutes). Patients will be randomly assigned, with a 1:1 ratio, into a deep NMB + low IAP group (train of four = 0, post-tetanic count = 1-3, IAP = 8 mmHg) and a moderate NMB + standard IAP group (train of four = 1-3, IAP = 12 mmHg). If the surgical workspace is inadequate, the surgeons can request a step increase of 1 mmHg in IAP during 3-min intervals. The upper limit of IAP will be set at 15 mmHg. Postoperative recovery will be assessed using the postoperative quality recovery scale (PQRS). The primary outcome of this trial is the PQRS nociceptive recovery (including pain and PONV) at postoperative day (POD) 1. The secondary outcomes include recovery in other PQRS domains at POD 1, and recovery in all PQRS domains in a post-anesthesia care unit, at POD 3 in the surgical wards, at hospital discharge, and at postoperative 30 days. For the sample size estimation, 110 patients in each group (220 in total) would be needed to detect an absolute increase rate of 20% in the PQRS nociceptive domain in the deep NMB + low IAP group at POD 1.

Discussion

This study investigates the effects of deep NMB combined with low IAP on postoperative PQRS nociceptive recovery in patients undergoing major laparoscopic gastrointestinal surgery. We expect that this deep NMB + low IAP strategy would improve postoperative pain and PONV following major laparoscopic gastrointestinal surgery.

Reappraisal of ischemia-reperfusion injury in a short duration laparoscopic surgery, a pilot study

Background

Serum biochemical changes during laparoscopic surgery and positive pressure pneumoperitoneum (PP) may reflect mild oxidative stress due to the ischemia-reperfusion (I/R) mechanism. However, there is still a controversy regarding the exact mechanism of PP in creating oxidative stress and whether the induction of PP causes I/R effects at all. To elucidate this debated issue, we studied, for the first time, the changes of I/R parameters in the serum, in a pilot study, during laparoscopic cholecystectomy using a reliable, independent exogenous oxidative biomarker, together with common intrinsic biomarkers of oxidative stress.

Patients and methods

Our study included 20 patients scheduled for elective laparoscopic cholecystectomy. We evaluated the levels of the extrinsic and endogenous markers for oxidative stress during awareness, under anesthesia, the end of surgery (abdominal CO2 evacuation), and 2 h afterward.

Results

After an initial increase in oxidative stress following anesthesia, we did not notice any further significant rise in the levels of the synthetic exogenous and the endogenous biomarkers at the end of the surgery and 2 h later on. However, a positive correlation was noted between the levels of both the intrinsic and extrinsic markers.

Conclusions

In our study, the capability of the extrinsic biomarker to detect mild oxidative stress was not validated. Our study stresses the heterogeneous nature of the oxidative reactions and the diversity of the endogenous and exogenous biomarkers while detecting various biochemical patterns under mild oxidative stress, during the short period of laparoscopic surgery.

Low-pressure Pneumoperitoneum With Abdominal Wall Lifting Versus Standard Pressure Pneumoperitoneum in Laparoscopic Fundoplication for Gastroesophageal Reflux Disease: A Propensity Score-matched Analysis

OBJECTIVE

The objective of this study was to compare the treatment results of low-pressure pneumoperitoneum with abdominal wall lifting (AWL+LP, 6 mm Hg) versus standard pressure pneumoperitoneum (SP, 12 mm Hg) during laparoscopic fundoplication for gastroesophageal reflux disease (GERD), using propensity score matching (PSM).

MATERIALS AND METHODS

A retrospective analysis was made of 362 patients, 123 in the AWL+LP group and 239 in the SP group, who underwent laparoscopic fundoplication for GERD from January 2010 to December 2017. Perioperative and prognostic outcomes were compared after PSM with 1:1 match.

RESULTS

After PSM, 107 matched pairs were obtained. Compared with the SP group at 30 and 60 minutes after pneumoperitoneal initiation, the AWL+LP group showed significantly lower end-tidal carbon dioxide value (P<0.001, <0.001, respectively), lower partial pressure of carbon dioxide value (P<0.001, 0.016, respectively) and significantly higher pH value (P<0.001, <0.001, respectively). However, postoperative shoulder pain, abdominal pain, and arrhythmia in the AWL+LP group were less than those in SP group (P=0.01, 0.017, 0.005, respectively). There was no significant difference in operative time (106.54±27.80 vs. 107.38±24.78 min), blood loss [15 mL (interquartile range: 12.5 to 20 mL) vs.15 mL (interquartile range: 10 to 20 mL)], length of stay (4 vs. 4 d), the wound ecchymosis [2 (1.87%) vs. 3 (2.80%)] and rates of recurrence [8 (7.48%) vs. 5 (4.67%)] between AWL+LP group and SP group.

CONCLUSION

AWL+LP resulted in comparable perioperative and prognostic outcomes with less impact on changes in cardiorespiratory function compared with SP approaches of laparoscopic fundoplication for GERD.

Hydromorphone Protects against CO2 Pneumoperitoneum-Induced Lung Injury via Heme Oxygenase-1-Regulated Mitochondrial Dynamics

Various pharmacological agents and protective methods have been shown to reverse pneumoperitoneum-related lung injury, but identifying the best strategy is challenging. Herein, we employed lung tissues and blood samples from C57BL/6 mice with pneumoperitoneum-induced lung injury and blood samples from patients who received laparoscopic gynecological surgery to investigate the therapeutic role of hydromorphone in pneumoperitoneum-induced lung injury along with the underlying mechanism. We found that pretreatment with hydromorphone alleviated lung injury in mice that underwent CO₂ insufflation, decreased the levels of myeloperoxidase (MPO), total oxidant status (TOS), and oxidative stress index (OSI), and increased total antioxidant status (TAS). In addition, after pretreatment with hydromorphone, upregulated HO-1 protein expression, reduced mitochondrial DNA content, and improved mitochondrial morphology and dynamics were observed in mice subjected to pneumoperitoneum. Immunohistochemical staining also verified that hydromorphone could increase the expression of HO-1 in lung tissues in mice subjected to CO₂ pneumoperitoneum. Notably, in mice treated with HO-1-siRNA, the protective effects of hydromorphone against pneumoperitoneum-induced lung injury were abolished, and hydromorphone did not have additional protective effects on mitochondria. Additionally, in clinical patients who received laparoscopic gynecological surgery, pretreatment with hydromorphone resulted in lower serum levels of club cell secretory protein-16 (CC-16) and intercellular adhesion molecule-1 (ICAM-1), a lower prooxidant-antioxidant balance (PAB), and higher heme oxygenase-1 (HO-1) activity than morphine pretreatment. Collectively, our results suggest that hydromorphone protects against CO₂ pneumoperitoneum-induced lung injury via HO-1-regulated mitochondrial dynamics and may be a promising strategy to treat CO₂ pneumoperitoneum-induced lung injury.

Effects of deep neuromuscular block with low-pressure pneumoperitoneum on respiratory mechanics and biotrauma in a steep Trendelenburg position

We hypothesized that deep neuromuscular blockade (NMB) with low-pressure pneumoperitoneum (PP) would improve respiratory mechanics and reduce biotrauma compared to moderate NMB with high-pressure PP in a steep Trendelenburg position. Seventy-four women undergoing robotic gynecologic surgery were randomly assigned to two equal groups. Moderate NMB group was maintained with a train of four count of 1–2 and PP at 12 mmHg. Deep NMB group was maintained with a post-tetanic count of 1–2 and PP at 8 mmHg. Inflammatory cytokines were measured at baseline, at the end of PP, and 24 h after surgery. Interleukin-6 increased significantly from baseline at the end of PP and 24 h after the surgery in moderate NMB group but not in deep NMB group (P_group*time = 0.036). The peak inspiratory, driving, and mean airway pressures were significantly higher in moderate NMB group than in deep NMB group at 15 min and 60 min after PP (P_group*time = 0.002, 0.003, and 0.048, respectively). In conclusion, deep NMB with low-pressure PP significantly suppressed the increase in interleukin-6 developed after PP, by significantly improving the respiratory mechanics compared to moderate NMB with high-pressure PP during robotic surgery.

Effect of volatile and total intravenous anesthesia on syndecan-1 shedding after minimally invasive gastrectomy: a randomized trial

This study aimed to compare the effects of volatile anesthesia and total intravenous anesthesia (TIVA) on syndecan-1 shedding in patients with gastric cancer undergoing minimally invasive gastrectomy. Patients were randomly assigned to either the Volatile (n = 68) or the TIVA (n = 68) group. Anesthesia was maintained with sevoflurane/remifentanil or propofol/remifentanil in the Volatile and TIVA groups, respectively. Serum syndecan-1 was evaluated at pre-operation, end of operation, and postoperative day (POD) 1. Inflammatory markers including white blood cell (WBC) count, neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein (CRP), were also measured at pre-operation, end of operation, and POD 1, 2, 3, and 5. The TIVA group showed significantly lower levels of syndecan-1 at the end of the operation compared to the Volatile group; however, no difference was seen between the groups at POD 1. The WBC count and NLR were significantly lower in the TIVA group at the end of the operation than the Volatile group, but there were no differences between the groups at POD 1, 2, 3, and 5. CRP levels were similar between the groups at all time points. In conclusion, despite TIVA being superior to volatile anesthesia in protecting endothelial glycocalyx during the operation, both did not prevent postoperative syndecan-1 shedding after gastrectomy.

Clinical trial registration number: NCT04183296 (ClinicalTrial.gov, 03/12/2019).

Changes in Acute Phase Proteins in Bitches after Laparoscopic, Midline, and Flank Ovariectomy Using the Same Method for Hemostasis

Simple Summary

Ovariectomy is a common surgical procedure in veterinary medicine, with many techniques involved. The aim of this study is to objectively evaluate the acute phase response by measuring the changes in a panel of acute phase proteins after applying three different ovariectomy techniques. C-reactive protein values showed increases of lower magnitude after laparoscopic ovariectomy compared with other techniques, indicating that this surgical technique induces a reduced inflammatory response and tissue damage. The use of this procedure is in agreement with the current tendency to use minimally invasive procedures for ovariectomy.

Abstract

Acute phase proteins (APP) are biomarkers of systemic inflammation, which allow monitoring the evolution of diseases, the response to treatments, and post-operative complications. Ovariectomy (OVE) is frequently performed in veterinary medicine and can be a useful model to evaluate surgical trauma and inflammation in the bitch. The objective was to investigate and compare the acute phase response (APR) after applying three different OVE techniques by measuring serum levels of C-reactive protein (CRP), haptoglobin (Hp), albumin (Alb), and paraoxonase-1 (PON-1). Forty-five intact bitches were included in the study, being randomly distributed into three groups: laparoscopic OVE (L), midline OVE (M), and flank OVE (F). Serum CRP, Hp, Alb, and PON-1 were measured before surgery, 1, 24, 72, and 168 h post-intervention. CRP levels increased significantly 24 h post-surgery in the M and F groups, but no significant variation was observed in the L group at any time of the study period. Hp was significantly higher in group L than in group F 72 h post-surgery. Alb and PON-1 showed no statistical difference among groups or among sampling periods. CRP response suggests that the use of laparoscopic procedures produce lower inflammation compared to open conventional approaches when performing OVE in the bitch.

Impact of pneumoperitoneum on intra-abdominal microcirculation blood flow: an experimental randomized controlled study of two insufflator models during transanal total mesorectal excision : An experimental randomized multi-arm trial with parallel treatment design

OBJECTIVE

To compare changes in microcirculation blood flow (MCBF) between pulsatile and continuous flow insufflation. Transanal total mesorectal excision (TaTME) was developed to improve the quality of the resection in rectal cancer surgery. The AirSeal IFS® insufflator facilitates the pelvic dissection, although evidence on the effects that continuous flow insufflation has on MCBF is scarce.

METHODS

Thirty-two pigs were randomly assigned to undergo a two-team TaTME procedure with continuous (n = 16) or pulsatile insufflation (n = 16). Each group was stratified according to two different pressure levels in both the abdominal and the transanal fields, 10 mmHg or 14 mmHg. A generalized estimating equations (GEE) model was used.

RESULTS

At an intra-abdominal pressure (IAP) of 10 mmHg, continuous insufflation was associated with a significantly lower MCBF reduction in colon mucosa [13% (IQR 11;14) vs. 21% (IQR 17;24) at 60 min], colon serosa [14% (IQR 9.2;18) vs. 25% (IQR 22;30) at 60 min], jejunal mucosa [13% (IQR 11;14) vs. 20% (IQR 20;22) at 60 min], renal cortex [18% (IQR 15;20) vs. 26% (IQR 26;29) at 60 min], and renal medulla [15% (IQR 11;20) vs. 20% (IQR 19;21) at 90 min]. At an IAP of 14 mmHg, MCBF in colon mucosa decreased 23% (IQR 14;27) in the continuous group and 28% (IQR 26;31) in the pulsatile group (p = 0.034).

CONCLUSION

TaTME using continuous flow insufflation was associated with a lower MCBF reduction in colon mucosa and serosa, jejunal mucosa, renal cortex, and renal medulla compared to pulsatile insufflation.

Laparoscopic procedures impact on mast cell mediators, extracellular matrix and adhesion scoring system in rats

Background

Laparoscopic procedures under certain pressure have the potential to cause intra-abdominal adhesions. However, the pathomechanism of this disorder is unknown. Release of mast cell mediators due to mast cell degranulation is thought to be the cause.

Materials and methods

Thirty male Sprague-Dawley rats were grouped into five groups (n = 6 per group): one control group and four intervention groups to which 60 min insufflation was performed using carbon dioxide at 5, 8, 10 and 12 mmHg. Seven days after laparoscopy, we euthanized and evaluated the levels of histamine, tryptase, and chymase of peritoneal fluid, the thickness of ECM of peritoneal tissue, and intraabdominal adhesion scoring system.

Results

Histamine and tryptase levels in peritoneal fluid were significantly higher at the 10- and 12 mm Hg intervention compared to control (histamine: 0.50 ± 0.35 vs. 0.41 ± 0.41 vs. 0.04 ± 0.02 ng/mL, respectively; and tryptase: 0.69 ± 0.11 vs. 0.65 ± 0.05 vs. 0.48 ± 0.02 ng/ml respectively). The ECM was significantly thicker in the intervention groups at 10- and 12-mm Hg compared to control (71.3 [66.7–85.2] vs. 48.4 [34.5–50.3] vs. 10.25 [8.7–12.1] μm, respectively). Moreover, the intra-abdominal scoring was also significantly higher in the intervention groups at 10- and 12 mm Hg compared to control (4 [0–4] vs. 4.5 [4–5], vs. 0, respectively).

Conclusions

Laparoscopic procedures increase the release of mast cell mediators in peritoneal fluid, the thickness of ECM and intraabdominal adhesion scoring in rats, implying that it might increase the possibility of intrabdominal adhesion in humans.

•

Laparoscopic procedures at specific pressures potentially cause intra-abdominal adhesion, however, its pathomechanism is still challenging to understand.

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Laparoscopic procedures increase the release of mast cell mediators in peritoneal fluid, the thickness of ECM and intraabdominal adhesion scoring in rats.

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Our findings imply that laparoscopic procedures might increase the possibility of intrabdominal adhesion in humans.

Risk Factors for Severe Complications After Laparoscopic Surgery for T3 or T4 Rectal Cancer for Chinese Patients: Experience from a Single Center

Background

Patients with rectal cancer are usually at advanced stage with or beyond serosa invasion in China. Severe complications after laparoscopic rectal surgery leads to prolonged hospitalization and high medical cost. This study aimed to explore risk factors for severe complications after laparoscopic surgery of T3 or T4 rectal cancer.

Material/Methods

A total of 287 patients diagnosed with T3 or T4 rectal cancer were enrolled from the Department of Gastrointestinal Surgery of Anhui Provincial Hospital from February 2012 to February 2017. Univariate analysis and multivariable logistic regression model were used to analyze the risk factors for severe complications (Clavien-Dindo grade ≥III) after laparoscopic surgery.

Results

Eighteen patients (6.25%) had severe complications; 15 patients were categorized as Clavien-Dindo grade III, and 3 patients were categorized as Clavien-Dindo grade IV. Univariate analysis showed that male gender, high preoperative white blood cells (WBC), diabetes mellitus, pulmonary dysfunction, and tumor distance from anus were associated with increased risk of severe complications after laparoscopic surgery for rectal cancer. Multivariate analysis showed that preoperative WBC ≥6.9×10⁹/L (OR=5.54 (1.58–19.45), P=0.008), diabetes mellitus (OR=13.07 (3.31–51.67), P=0.000) and pulmonary dysfunction (OR=7.75 (1.69–35.63), P=0.008) were independent risk factors for postoperative severe complications.

Conclusions

Preoperative high white blood cells, diabetes mellitus and pulmonary dysfunction were independent risk factors for severe complications after laparoscopic surgery for T3 or T4 rectal cancer.

The effect of laparoscopy on mast cell degranulation and mesothelium thickness in rats

Background

Laparoscopy induces adhesion due to ischemia-reperfusion injury. However, the detail pathomechanism is poorly understood. This study aimed to investigate the impact of laparoscopy on mast cell and mesothelium morphological changes in the rat.

Methods

Forty-nine males of Sprague-Dawley Rattus norvegicus were divided into four groups: a) control and b) intervention groups P1, P2, and P3 that underwent 60 min laparoscopic using carbon dioxide (CO₂) insufflation at 8, 10, and 12 mmHg groups, respectively. Serum hydrogen peroxide (H₂O₂), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), and oxidative stress index (OSI) levels were determined 24 h after laparoscopy. Histopathological analyses of mast cell infiltration and degranulation and mesothelium thickness in the liver, greater omentum, mesenterium, small intestine, and peritoneum were performed 7 days after the procedure.

Results

H₂O₂, MDA, and OSI levels were significantly increased in the intervention groups compared with the control (p<0.05), while the SOD and CAT levels were decreased in the intervention groups compared with the control (p<0.05). Mast cell infiltration and degranulation were higher in the intervention groups than in control (p<0.05), while the mesothelium thickness was significantly lower in the laparoscopic groups than in control (p<0.05). Interestingly, the decrease in mesothelium thickness was strongly associated with the increase in mast cell infiltration and degranulation (p<0.01).

Conclusions

Our study shows that laparoscopy in rats increases mast cell infiltration and degranulation, which also results in and correlates with a decrease in mesothelial thickness.

Effects of intra-abdominal pressure on laparoscopic working space in domestic rabbits (Oryctolagus cuniculus)

OBJECTIVE

To assess the effects of 3 intra-abdominal pressures (IAPs) on pneumoperitoneal (laparoscopic working space) volume in domestic rabbits (Oryctolagus cuniculus).

ANIMALS

6 female New Zealand White rabbits.

PROCEDURES

A Latin-square design was used to randomly allocate sequences of 3 IAPs (4, 8, and 12 mm Hg) to each rabbit in a crossover study. Rabbits were anesthetized, subumbilical cannulae were placed, and CT scans were performed to obtain baseline measurements. Each IAP was achieved with CO₂ insufflation and maintained for ≥ 15 minutes; CT scans were performed with rabbits in dorsal, left lateral oblique, and right lateral oblique recumbency. The abdomen was desufflated for 5 minutes between treatments (the 3 IAPs). Pneumoperitoneal volumes were calculated from CT measurements with 3-D medical imaging software. Mixed linear regression models evaluated effects of IAP, rabbit position, and treatment order on working space volume.

RESULTS

Mean working space volume at an IAP of 8 mm Hg was significantly greater (a 19% increase) than that at 4 mm Hg, and was significantly greater (a 6.9% increase) at 12 mm Hg than that at 8 mm Hg. Treatment order, but not rabbit position, also had a significant effect on working space. Minor adverse effects reported in other species were observed in some rabbits.

CONCLUSIONS AND CLINICAL RELEVANCE

A nonlinear increase in abdominal working space was observed with increasing IAP. Depending on the type of procedure and visual access requirements, IAPs > 8 mm Hg may not provide a clinically important benefit for laparoscopy in rabbits.

Protective effects of postconditioning in transvaginally created pneumoperitoneum

There are reports of ischemic complications in clinical practice after laparoscopy using pneumoperitoneum. Conditioning has a beneficial effect for various ischemic diseases. This experimental study was designed to evaluate the effects of postconditioning in transvaginally created pneumoperitoneum. Sixty adult female rats, weighing 300±50 g were divided into four equal groups. Pneumoperitoneum was created by CO₂ insufflation under a pressure of 10 mmHg. Rats in the first group (sham) were subjected to only sham-operation or gas insufflation. The second group (TV/PP) was subjected to pneumoperitoneum for 60 min followed by 30 min of desufflation. The third group (post-5) was subjected to pneumoperitoneum for 60 min followed by 5 min of desufflation, 5 min of insufflation and again followed by 30 min of desufflation. The fourth group (post-2.5) was subjected to pneumoperitoneum for 60 min followed by 2.5 min of desufflation and 2.5 min of insufflation-repeated in two cycles- and then followed by 30 min of desufflation. The rats were sacrificed, and blood was collected after 30 min, 2 and 6 h from the last desufflation. Levels of oxidative stress markers, malondialdehyde (MDA), superoxide dismutase (SOD), reduced glutathione (GSH), sulfhydryl groups (SH) and inflammatory cytokine TNF-α, were analyzed. Levels of MDA in the post-5 group were significantly reduced compared to the TV/PP and post-2.5 groups. The level of GSH in TV/PP animals was markedly reduced compared to the Sham, Post-5 and Post-2.5 groups. In addition, levels of SH were increased in the Post-5 group in comparison to the Sham, TV/PP and Post-2.5 groups. No difference in the activity of SOD between the groups was found, and the concentration of TNF-α in TV/PP animals was significantly higher than that in the Sham and postconditioning groups. Overall, the results of the present study indicate that postconditioning can reduce pneumoperitoneum-induced oxidative injury.

Notoginsenoside R1 Suppresses Inflammatory Signaling and Rescues Renal Ischemia-Reperfusion Injury in Experimental Rats

Background

Notoginsenoside R1 (NR) is a major dynamic constituent of Panax notoginseng found to possess anti-inflammatory activity against various inflammatory diseases. However, its protective effects against renal ischemia-reperfusion (I/R) injury have not been elucidated. In male Wistar rats, we induced I/R under general anesthesia by occluding the renal artery for 60 min, followed by reperfusion and right nephrectomy.

Material/Methods

Rats were randomized to 4 groups: a sham group, an I/R group, an NR-pretreated (50 mg/kg) before I/R induction group, and an NR control group. All animals were killed at 72 h after I/R induction. Blood and renal tissues were collected, and histological and basic renal function parameters were assessed. In addition, levels of various kidney markers and proinflammatory cytokines were measured using RT-PCR, ELISA, and immunohistochemistry analysis.

Results

After I/R induction, the onset of renal dysfunction was shown by the elevated levels of serum urea, creatinine levels, and histological evaluation, showing a 2-fold increase in the renal failure markers kim-1 and NGAL compared to control rats. Rats pretreated with NR before I/R induction had significantly better renal functions, with attenuated levels of oxidative markers, restored levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), tumor growth factor-β1 (TGF-β1), INF-γ, and IL-6, and increased anti-inflammatory cytokine levels (IL-10) compared to I/R-induced rats.

Conclusions

NR suppressed I/R-induced inflammatory cytokines production by suppressing oxidative stress and kidney markers, suggesting that NR is a promising drug candidate for prevention, progression, and treatment of renal dysfunction.

Association of Cholecystectomy with the Risk of Prostate Cancer in Patients with Gallstones

Objectives: To assess the association of cholecystectomy with the risk of prostate cancer in patients with gallstones. Methods: This nationwide population-based cohort study was conducted by retrieving the Longitudinal Health Insurance Research Database (LHID2000) for inpatient claims in the Taiwan National Health Insurance (NHI) program. The study cohort consisted of 72,606 men aged ≥ 20 years with gallstones undergoing cholecystectomy between 2000 and 2010. The control cohort consisted of the men with gallstones, but without cholecystectomy, by 1:1 propensity score matching with the study cohort based on age, sex, urbanization, occupation, comorbidities, and the index date. We compared the hazard ratio of prostate cancer between both of the cohorts. Results: The incidence of prostate cancer was 0.76/1000 person-years for the non-cholecystectomy cohort and 1.28/1000 person-years for the cholecystectomy cohort [aHR (adjusted hazard ratio) = 1.67, 95% confidence interval (CI = 1.45–1.92), respectively (p < 0.001). When compared with the non-cholecystectomy cohort, the hazard ratio of prostate cancer for the cholecystectomy cohort was 1.49-fold greater (95% CI = 1.04–2.11) for follow-up ≤ 1 year, 1.52-fold greater (95% CI = 1.24–1.86) for follow-up 1–5 years, and 1.99-fold greater (95% CI = 1.56–2.53) for follow-up > 5 years, respectively. Conclusions: Cholecystectomy is associated with an increased hazard ratio of prostate cancer in gallstones patients, and the risk increases with an incremental period of follow-up. This observational study cannot ascertain the detrimental mechanisms of cholecystectomy for the development of prostate cancer, and cholecystectomy is not recommended for the prevention of prostate cancer based on our study.

A comparison of the oxidative stress response in single-incision laparoscopic versus multi-trocar laparoscopic totally extraperitoneal inguinal hernia repair

Introduction

Surgical treatment is always associated with tissue damage and the subsequent development of oxidative stress.

Aim

To compare the oxidative stress response in patients treated operatively for inguinal hernia with multi-trocar laparoscopic totally extraperitoneal technique (TEP) or single-incision laparoscopic totally extraperitoneal technique (TEP-SI).

Material and methods

A randomized group of 34 patients with one-sided inguinal hernia was enrolled in the study. Seventeen patients were treated with a standard TEP method (group 1) and the other 17 patients were treated with the TEP-SI technique (group 2). Thiobarbituric acid reactive substances (TBARS) and total antioxidant status (TAS) as the oxidative stress markers were measured before surgery (0), 1 day (1) and 4 days (2) after surgery.

Results

A decrease in TAS on the first day after surgery was observed in both groups. Sustained reduction on the fourth day after surgery was observed in group 1, whereas in group 2 an increase followed. A statistically significant difference was observed in TAS (2 : 0) ratio with a meaningful decrease in group 1. TBARS concentration was elevated 1 day after surgery in both groups. It remained at an elevated level on the fourth day after surgery in group 1, while it decreased in group 2. The duration of surgery was higher in group 2 (mean: 57.5 min) than in group 1 (mean: 50.0 min) (p = 0.0286).

Conclusions

Oxidative stress levels are lower in patients treated operatively by TEP-SI technique than by TEP. TEP-SI may be considered as a less invasive technique associated with less tissue injury.

Randomized clinical trial of the effect of intraoperative humidified carbon dioxide insufflation in open laparotomy for colorectal resection

Background

Animal studies have shown that peritoneal injury can be minimized by insufflating the abdominal cavity with warm humidified carbon dioxide gas.

Methods

A single‐blind RCT was performed at a tertiary colorectal unit. Inclusion criteria were patient aged 18 years and over undergoing open elective surgery. The intervention group received warmed (37°C), humidified (98 per cent relative humidity) carbon dioxide (WHCO₂ group). Multiple markers of peritoneal inflammation and oxidative damage were used to compare groups, including cytokines and chemokines, apoptosis, the 3‐chlorotyrosine/native tyrosine ratio, and light microscopy on peritoneal biopsies at the start (T₀) and end (T_end) of the operation. Postoperative clinical outcomes were compared between the groups.

Results

Of 40 patients enrolled, 20 in the WHCO₂ group and 19 in the control group were available for analysis. A significant log(T_end/T₀) difference between control and WHCO₂ groups was documented for interleukin (IL) 2 (5·3 versus 2·8 respectively; P = 0·028) and IL‐4 (3·5 versus 2·0; P = 0·041), whereas apoptosis assays documented no significant change in caspase activity, and similar apoptosis rates were documented along the peritoneal edge in both groups. The 3‐chlorotyrosine/tyrosine ratio had increased at T_end by 1·1‐fold in the WHCO₂ group and by 3·1‐fold in the control group. Under light microscopy, peritoneum was visible in 11 of 19 samples from the control group and in 19 of 20 samples from the WHCO₂ group (P = 0·006). The only difference in clinical outcomes between intervention and control groups was the number of days to passage of flatus (2·5 versus 5·0 days respectively; P = 0·008).

Conclusion

The use of warmed, humidified carbon dioxide appears to reduce some markers related to peritoneal oxidative damage during laparotomy. No difference was observed in clinical outcomes, but the study was underpowered for analysis of surgical results. Registration number: NCT02975947 ( http://www.clinicaltrials.gov/).

Scintigraphic Evaluation of the Impact of Pneumoperitoneum on Renal Blood Flow: A Rabbit Model

Background: Increased intra-abdominal pressure resulting from pneumoperitoneum can cause renal physiological changes, such as oliguria and anuria, in mammals. Although videolaparoscopic operations are common, the occurrence of renal lesions due to these procedures has not been precisely documented in the literature. The aim of this study was to evaluate the impact of pneumoperitoneum on renal blood flow using renal scintigraphy in a rabbit model. Methods: Six New Zealand male rabbits weighing 3 kg, previously anesthetized, were mechanically ventilated and underwent pneumoperitoneum. Each animal served as its own control and was analyzed in two different moments: [99mTc] diethylenetriaminepentaacetic acid (DTPA) renal blood flow evaluation in baseline conditions (T0) and 30 minutes after installation of 15 mmHg-pneumoperitoneum (T1). The animals were monitored throughout the study by capnography, oximetry, and arterial pressure median, and were euthanized at the end of the experiment. Results: The quantitative analysis of the scintigraphic images of renal uptake of the radiopharmaceutical evidence reduced renal arterial blood flow during pneumoperitoneum. Compared with baseline conditions, all animals presented a reduction of renal blood flow varying from 16% to 82%, with mean [±standard deviation] of 53% [±24%]. Conclusions: Pneumoperitoneum induces a significant reduction of the renal blood flow, as determined in this experimental method in rabbits and dynamic renal scintigraphy with [99mTc] DTPA is an adequate method to investigate this event in the experimental setting.

An individualised versus a conventional pneumoperitoneum pressure strategy during colorectal laparoscopic surgery: rationale and study protocol for a multicentre randomised clinical study

Background

A recent study shows that a multifaceted strategy using an individualised intra-abdominal pressure titration strategy during colorectal laparoscopic surgery results in an acceptable workspace at low intra-abdominal pressure in most patients. The multifaceted strategy, focused on lower to individualised intra-abdominal pressures, includes prestretching the abdominal wall during initial insufflation, deep neuromuscular blockade, low tidal volume ventilation settings and a modified lithotomy position. The study presented here tests the hypothesis that this strategy improves outcomes of patients scheduled for colorectal laparoscopic surgery.

Methods

The Individualized Pneumoperitoneum Pressure in Colorectal Laparoscopic Surgery versus Standard Therapy (IPPCollapse-II) study is a multicentre, two-arm, parallel-group, single-blinded randomised 1:1 clinical study that runs in four academic hospitals in Spain. Patients scheduled for colorectal laparoscopic surgery with American Society of Anesthesiologists classification I to III who are aged > 18 years and are without cognitive deficits are randomised to an individualised pneumoperitoneum pressure strategy (the intervention group) or to a conventional pneumoperitoneum pressure strategy (the control group). The primary outcome is recovery assessed with the Post-operative Quality of Recovery Scale (PQRS) at postoperative day 1. Secondary outcomes include PQRS score in the post anaesthesia care unit and at postoperative day 3, postoperative complications until postoperative day 28, hospital length of stay and process-related outcomes.

Discussion

The IPPCollapse-II study will be the first randomised clinical study that assesses the impact of an individualised pneumoperitoneum pressure strategy focused on working with the lowest intra-abdominal pressure during colorectal laparoscopic surgery on relevant patient-centred outcomes. The results of this large study, to be disseminated through conference presentations and publications in international peer-reviewed journals, are of ultimate importance for optimising the care and safety of laparoscopic abdominal surgery. Selection of patient-reported outcomes as the primary outcome of this study facilitates the translation into clinical practice. Access to source data will be made available through anonymised datasets upon request and after agreement of the Steering Committee of the IPPCollapse-II study.

Trial registration

ClinicalTrials.gov, NCT02773173. Registered on 16 May 2016. EudraCT, 2016-001693-15. Registered on 8 August 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3255-1) contains supplementary material, which is available to authorized users.

Effects of propofol on the inflammatory response during robot-assisted laparoscopic radical prostatectomy: a prospective randomized controlled study

Robot-assisted laparoscopic radical prostatectomy (RALRP) is a minimally invasive procedure; however, some amount of surgical trauma that can trigger systemic inflammation remains. Moreover, pneumoperitoneum during RALRP induces ischemia–reperfusion injury (IRI). Propofol, an anesthetic, is known to have anti-inflammatory and antioxidant properties. In the present study, we compared the effects of propofol with those of desflurane on inflammation and IRI during RALRP via measurements of different biomarkers and evaluation of perioperative renal function. Fifty patients were randomized to receive either desflurane (n = 25) or propofol (n = 25) with remifentanil during RALRP. Serum levels of interleukin (IL)-6 (IL-6), tumor necrosis factor alpha, C-reactive protein, and nitric oxide were measured 10 min after anesthesia induction (T1), 100 min after carbon dioxide (CO₂) insufflation (T2), and 10 min after CO₂ deflation (T3). Perioperative urine outputs and the serum creatinine level at 24 h after surgery were also recorded. We found that IL-6 levels at T2 and T3 were higher than those at T1 in both groups, although the increases were significant attenuated only in the propofol group. The other parameters showed no differences among the three time points in both groups. The intraoperative urine output was significantly higher in the propofol group than in the desflurane group, while the creatinine level showed no significant changes in either group. Our findings suggest that propofol can not only attenuate the inflammatory response during and after pneumoperitoneum in patients undergoing RALRP but also prevent oliguria during pneumoperitoneum.

Comparison of the Effects of Sevoflurane and Desflurane on Thiol-Disulfide Homeostasis in Patients Undergoing Laparoscopic Cholecystectomy

Objective

This study aims to compare the effects of different inhalation anesthetics on oxidative status by measuring thiol-disulfide homeostasis in laparoscopic cholecystectomy surgeries. The effect of inhaler agents on thiol-disulfide homeostasis that shows the oxidative status in laparoscopic cholecystectomy is unknown.

Materials and Methods

In this study, 71 patients planned to undergo laparoscopic cholecystectomy under general anesthesia were included. They were divided into two groups: desflurane (group D, n: 35) and sevoflurane (group S, n: 36). Blood samples were taken before induction (T1), at 30th minute of insufflation (T2) (30th min of ischemia), and at 30th min postdeflation (T3) (30th min of reperfusion). The native thiols (-SH) and total thiols (-SH+ -SS) were determined. The amounts of disulfide (-SS), disulfide/native thiol percent ratios (-SS/-SH), disulfide/total thiol percent ratios (-SS/-SH+-SS), and native thiol/total thiol percent ratios (-SH/-SH+ -SS) were calculated.

Results

In the sevoflurane group, preoperative values and intraoperative 30th-minute SS-SH ratio were significantly reduced (p=0.017). In the desflurane group, intraoperative native thiol values and postdeflation levels significantly decreased compared to those in the preoperative values (p<0.001).

Conclusion

We think that the usage of sevoflurane was more protective in terms of the oxidative damage occurring during laparoscopic surgery.

High-pressure carbon dioxide pneumoperitoneum induces oxidative stress and mitochondria-associated apoptotic pathway in rabbit kidneys with severe hydronephrosis

The primary aim of the present study was to investigate the potential effect of high‑pressure carbon dioxide (CO2) pneumoperitoneum on kidneys with severe hydronephrosis and to investigate the possible underlying mechanism. A total of 18 rabbits underwent a surgical procedure inducing severe hydronephrosis. Rabbits were then divided at random into three groups (n=6 each) and subjected to intraabdominal pressure of 0, 8 or 18 mmHg, respectively. CO2 inflation lasted for 90 min in the pneumoperitoneum groups. Oxidative stress was assessed by measurements of reactive oxygen species (ROS). Activation of apoptosis was analyzed by western blot analysis of B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated x protein (Bax), cytochrome c (Cyt c), caspase‑3 and caspase‑9 levels. In addition, TUNEL assay, hematoxylin and eosin (H&E) staining, measurement of mitochondrial membrane potential (MMP) and detection of changes to kidney ultramicrostructure were performed. In the 0 and 8 mmHg groups, all results were normal and similar. However, in the 18 mmHg group, the kidneys suffered oxidative damage and mitochondrial injuries, and increased ROS levels, lower MMP and mitochondrial vacuolization were observed. Furthermore, the mitochondrial/caspase‑dependent pathway of apoptosis was activated, as indicated by the apoptotic index, and the expression levels and translocation of Bax, Bcl‑2, Cyt c, caspase‑3 and caspase‑9. Therefore, it is concluded that high‑pressure CO2 pneumoperitoneum induces oxidative damage and apoptosis in rabbit kidneys with severe hydronephrosis, which is associated with the mitochondrial apoptotic pathway.

Pneumoperitoneum induced ischemia-reperfusion injury of the peritoneum - Preconditioning may reduce the negative side-effects caused by carbon-dioxide pneumoperitoneum - Pilot study

INTRODUCTION

Laparoscopy is more beneficial than the conventional open technique, however the pneumoperitoneum created may have an ischemic side effect.

OBJECTIVE

Our aim was to evaluate the protective effects of preconditioning during laparoscopic cholecystectomies (LC).

METHODS

30 patients were randomized into 2 groups: I. PreC (preconditioning: 5 min. inflation, 5 min. deflation, followed by conventional LC), II: LC (conventional LC). Blood samples were taken before hospitalization (C = control), before surgery, after anaesthesia (B.S.), after surgery (A.S.) and 24 hours after the procedure (24 h). Measured parameters were: malondialdehyde (MDA), reduced glutathione (GSH), sulfhydril groups (-SH), superoxide-dismutase (SOD), catalase (CAT), myeloperoxidase (MPO), length of hospitalization and pain (VAS = visual analogue scale).

RESULTS

Compared to the BS levels, no significant changes were detected in SOD's activity and MDA levels. GSH concentrations were significantly increased in the PreC group after operation. SH-, MPO, CAT and liver function enzymes were not significantly different. Hospitalization was shorter in the PreC group. Based on the VAS score patients had less pain in the PreC group.

CONCLUSION

Significant differences concerning PreC group were found in GSH values. In the PreC group pain decreased by 2-2.5 units following the procedure, 24 h after surgery, and hospitalisation was also significantly shorter. In our pilot study the potential protective effect of preconditioning could be defined.

Oxidative damage and mitochondrial injuries differ following pneumoperitoneum pressure in rabbit models of varying degrees of hydronephrosis

The influence of intraabdominal pressure which is necessary to maintain the operating area during the surgery cannot be ignored especially on the kidneys. Many articles have reported the effect of intraabdominal pressure on normal kidneys. However, the influence of intraabdominal pressure on hydronephrosis kidneys is rarely studied. The aim of the present study was to clarify whether intraabdominal pressure tolerance is modified in various degrees of kidney hydronephrosis by evaluating oxidative damage and mitochondrial injuries. A total of 72 rabbits were randomly divided into three groups (groups N, M and S, which represented rabbits with no, mild and severe hydronephrosis, respectively). Rabbits in groups M (n=24) and S (n=24) underwent a surgical procedure inducing mild or severe hydronephrosis, respectively. Subsequently, rabbits in all groups were allocated to 4 subgroups (N0‑N3, M0‑M3 and S0‑S3) consisting of 6 rabbits each. Groups 0 to 3 were, respectively, subjected to intraabdominal pressures of 0, 5, 10 and 15 mmHg. Oxidative damage was assessed by analyzing levels of reactive oxygen species (ROS), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH‑Px), catalase (CAT) and lactate (LD). Mitochondrial injuries were assessed based on mitochondrial membrane potential (MMP) alterations, mitochondrial structure and cytochrome c (cytc) protein expression, as measured by JC‑1 staining, electron microscopy and western blotting, respectively. Oxidative damage and mitochondrial injuries were noticeably exacerbated in group N and M with increased levels of ROS, MDA and LD, decreased levels of SOD, GSH‑Px, CAT and MMP, mitochondrial vacuolization and higher expression of cytc when the intraabdominal pressure reached 15 mmHg. In group S, these alterations occurred at pressures of 10 and 15 mmHg. Therefore, it was concluded that in rabbits exposed to pneumoperitoneal pressure, kidneys with severe hydronephrosis were more likely to suffer from oxidative damage and mitochondrial injuries compared with kidneys with mild hydronephrosis and normal kidneys.

Hydrogen protects against liver injury during CO2 pneumoperitoneum in rats

The aim of the current study was to identify the protective effect of hydrogen gas against liver injury during CO₂ pneumoperitoneum. Rats were randomly divided into three groups: control group (C group), pneumoperitoneum group (P15 group) and hydrogen group (H₂ group). Rats in the C group were subjected to anesthesia for 90 min. Rats in the P15 group received an abdominal insufflation of CO₂ for 90 min at an intra-abdominal pressure of 15 mmHg. Rats in the H₂ group received a hypodermic injection of hydrogen gas (0.2 mL/kg) and after 10 min they received an abdominal insufflation of CO₂ for 90 min at an intra-abdominal pressure of 15 mmHg. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured to evaluate liver function. Malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) content were measured to evaluate oxidative stress. Nuclear factor E2-related factor 2 (Nrf2) and Nrf2 downstream target genes, apoptosis-related genes and inflammatory cytokine mRNA and protein expression were detected. Liver injury was detected under the microscope. Our results revealed that liver function, antioxidants content, inflammation and liver injury were improved after hydrogen preconditioning in H₂ group compared with P15 group. Overall, our results revealed that subcutaneous hydrogen injection could exert a protective effect against liver injury during CO₂ pneumoperitoneum through reducing oxidative stress, cell apoptosis and inflammatory cytokines release.

Effects of low intraperitoneal pressure and a warmed, humidified carbon dioxide gas in laparoscopic surgery: a randomized clinical trial

Laparoscopic surgery technology continues to advance. However, much less attention has been focused on how alteration of the laparoscopic surgical environment might improve clinical outcomes. We conducted a randomized, 2 × 2 factorial trial to evaluate whether low intraperitoneal pressure (IPP) (8 mmHg) and/or warmed, humidified CO₂ (WH) gas are better for minimizing the adverse impact of a CO₂ pneumoperitoneum on the peritoneal environment during laparoscopic surgery and for improving clinical outcomes compared to the standard IPP (12 mmHg) and/or cool and dry CO₂ (CD) gas. Herein we show that low IPP and WH gas may decrease inflammation in the laparoscopic surgical environment, resulting in better clinical outcomes. Low IPP and/or WH gas significantly lowered expression of inflammation-related genes in peritoneal tissues compared to the standard IPP and/or CD gas. The odds ratios of a visual analogue scale (VAS) pain score >30 in the ward was 0.18 (95% CI: 0.06, 0.52) at 12 hours and 0.06 (95% CI: 0.01, 0.26) at 24 hours in the low IPP group versus the standard IPP group, and 0.16 (95% CI: 0.05, 0.49) at 0 hours and 0.29 (95% CI: 0.10, 0.79) at 12 hours in the WH gas group versus the CD gas group.

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.

Changes in the coelomic microclimate during carbon dioxide laparoscopy: morphological and functional implications

In this article the adverse effects of laparoscopic CO2 pneumoperitoneum and coelomic climate change, and their potential prevention by warmed, humidified carbon dioxide insufflation are reviewed. The use of pressurized cold, dry carbon dioxide (C02) pneumoperitoneum causes a number of local effects on the peritoneal mesothelium, as well as systemic effects. These can be observed at a macroscopic, microscopic, cellular and metabolic level. Local effects include evaporative cooling, oxidative stress, desiccation of mesothelium, disruption of mesothelial cell junctions and glycocalyx, diminished scavenging of reactive oxygen species, decreased peritoneal blood flow, peritoneal acidosis, peritoneal hypoxia or necrosis, exposure of the basal lamina and extracellular matrix, lymphocyte infiltration, and generation of peritoneal cytokines such as IL-1, IL-6, IL-8 and TNFα. Such damage is increased by high CO2 insufflation pressures and gas velocities and prolonged laparoscopic procedures. The resulting disruption of the glycocalyx, mesothelial cell barrier and exposure of the extracellular matrix creates a cascade of immunological and pro-inflammatory events and favours tumour cell implantation. Systemic effects include cardiopulmonary and respiratory changes, hypothermia and acidosis. Such coelomic climate change can be prevented by the use of lower insufflation pressures and preconditioned warm humidified CO2. By achieving a more physiological temperature, pressure and humidity, the coelomic microenvironment can be better preserved during pneumoperitoneum. This has the potential clinical benefits of maintaining isothermia and perfusion, reducing postoperative pain, preventing adhesions and inhibiting cancer cell implantation in laparoscopic surgery.

Changes in the coelomic microclimate during carbon dioxide laparoscopy: morphological and functional implications

In this article the adverse effects of laparoscopic CO2 pneumoperitoneum and coelomic climate change, and their potential prevention by warmed, humidified carbon dioxide insufflation are reviewed. The use of pressurized cold, dry carbon dioxide (C02) pneumoperitoneum causes a number of local effects on the peritoneal mesothelium, as well as systemic effects. These can be observed at a macroscopic, microscopic, cellular and metabolic level. Local effects include evaporative cooling, oxidative stress, desiccation of mesothelium, disruption of mesothelial cell junctions and glycocalyx, diminished scavenging of reactive oxygen species, decreased peritoneal blood flow, peritoneal acidosis, peritoneal hypoxia or necrosis, exposure of the basal lamina and extracellular matrix, lymphocyte infiltration, and generation of peritoneal cytokines such as IL-1, IL-6, IL-8 and TNFα. Such damage is increased by high CO2 insufflation pressures and gas velocities and prolonged laparoscopic procedures. The resulting disruption of the glycocalyx, mesothelial cell barrier and exposure of the extracellular matrix creates a cascade of immunological and pro-inflammatory events and favours tumour cell implantation. Systemic effects include cardiopulmonary and respiratory changes, hypothermia and acidosis. Such coelomic climate change can be prevented by the use of lower insufflation pressures and preconditioned warm humidified CO2. By achieving a more physiological temperature, pressure and humidity, the coelomic microenvironment can be better preserved during pneumoperitoneum. This has the potential clinical benefits of maintaining isothermia and perfusion, reducing postoperative pain, preventing adhesions and inhibiting cancer cell implantation in laparoscopic surgery.

The effects of adding ischemic preconditioning during desflurane inhalation anesthesia or propofol total intravenous anesthesia on pneumoperitoneum-induced oxidative stress

BACKGROUND

The aim of the study was to explore the differences in oxidative stress during anesthesia with desflurane/N₂O or propofol/remifentanil in patients undergoing laparoscopic cholecystectomy and additionally to evaluate the differential effects of desflurane and propofol on ischemic preconditioning (IP).

MATERIALS AND METHODS

One hundred patients were randomly allocated to four groups. For anesthesia maintenance, the inhalation group (Group I) and the inhalation plus IP group (Group IIP) received desflurane at an end-tidal concentration of 4-6 vol% in oxygen/N₂O, and the TIVA group (Group T) and TIVA plus IP group (Group TIP) received infusions of propofol and remifentanil. In Groups IIP and TIP, IP was carried out by 10 min of pneumoperitoneum followed by 10 min of deflation. Preoperative and postoperative plasma total antioxidant status (TAS), total oxidant status (TOS), paraoxonase, stimulated paraoxonase, arylesterase, ceruloplasmin, and myeloperoxidase levels were analyzed; oxidative stress index (OSI) was calculated.

RESULTS

When oxidative stress parameters were compared between groups, myeloperoxidase values in Group I were statistically significantly lower compared to Group TIP (p = .004 with Bonferroni's correction). There were no differences between preoperative and postoperative TAS, paraoxonase, stimulated paraoxonase, arylesterase, or ceruloplasmin levels (p > .05). In intragroup evaluations, postoperative paraoxonase and stimulated paraoxonase levels were found to be lower than preoperative values in Group TIP (p = .021 and .012, respectively).

CONCLUSION

In laparoscopic cholecystectomy lasting less than 60 min, there were no differences in the measured oxidative stress parameters between maintenance of anesthesia by desflurane/N₂O and propofol/remifentanil/N₂O. The addition of 10 min IP administration during both anesthesia techniques did not result in additional changes in the analyzed oxidative stress.

Role of the peritoneal cavity in the prevention of postoperative adhesions, pain, and fatigue

A surgical trauma results within minutes in exudation, platelets, and fibrin deposition. Within hours, the denuded area is covered by tissue repair cells/macrophages, starting a cascade of events. Epithelial repair starts on day 1 and is terminated by day 3. If repair is delayed by decreased fibrinolysis, local inflammation, or factors in peritoneal fluid, fibroblast growth starting on day 3 and angiogenesis starting on day 5 results in adhesion formation. For adhesion formation, quantitatively more important are factors released into the peritoneal fluid after retraction of the fragile mesothelial cells and acute inflammation of the entire peritoneal cavity. This is caused by mechanical trauma, hypoxia (e.g., CO₂ pneumoperitoneum), reactive oxygen species (ROS; e.g., open surgery), desiccation, or presence of blood, and this is more severe at higher temperatures. The inflammation at trauma sites is delayed by necrotic tissue, resorbable sutures, vascularization damage, and oxidative stress. Prevention of adhesion formation therefore consists of the prevention of acute inflammation in the peritoneal cavity by means of gentle tissue handling, the addition of more than 5% N₂O to the CO₂ pneumoperitoneum, cooling the abdomen to 30°C, prevention of desiccation, a short duration of surgery, and, at the end of surgery, meticulous hemostasis, thorough lavage, application of a barrier to injury sites, and administration of dexamethasone. With this combined therapy, nearly adhesion-free surgery can be performed today. Conditioning alone results in some 85% adhesion prevention, barriers alone in 40%-50%.

Pretreatment with endothelium-derived nitric oxide synthesis modulators on gastrointestinal microcirculation during NOTES: an experimental study

BACKGROUND AND STUDY AIMS

On-demand endoscopic insufflation during natural orifice transluminal endoscopic surgery (NOTES) adversely affects microcirculatory blood flow (MBF), even with low mean intra-abdominal pressure, suggesting that shear stress caused by time-varying flow fluctuations has a great impact on microcirculation. As shear stress is inversely related to vascular diameter, nitric oxide (NO) production acts as a brake to vasoconstriction.

OBJECTIVE

To assess whether pretreatment by NO synthesis modulators protects gastrointestinal MBF during transgastric peritoneoscopy.

METHODS

Fourteen pigs submitted to cholecystectomy by endoscope CO₂ insufflation for 60 min were randomized into 2 groups: (1) 150 mg/kg of N-acetyl cysteine (NAC, n = 7) and (2) 4 ml/kg of hypertonic saline 7.5 % (HS, n = 7), and compared to a non-treated NOTES group (n = 7). Five animals made up a sham group. Colored microspheres were used to assess changes in MBF.

RESULTS

The average level of intra-abdominal pressure was similar in all groups (9 mmHg). In NOTES group microcirculation decrease compared with baseline was greater in renal cortex, mesocolon, and mesentery (41, 42, 44 %, respectively, p < 0.01) than in renal medulla, colon, and small bowel (29, 32, 34, respectively, p < 0.05). NAC avoided the peritoneoscopy effect on renal medulla and cortex (4 and 14 % decrease, respectively) and reduced the impact on colon and small bowel (20 % decrease). HS eliminated MBF changes in colon and small bowel (14 % decrease) and modulated MBF in renal medulla and cortex (19 % decrease). Neither treatment influenced mesentery MBF decrease.

CONCLUSIONS

Both pretreatments can effectively attenuate peritoneoscopy-induced deleterious effects on gastrointestinal MBF.

A prospective double-blinded randomized controlled trial comparing systemic stress response in Laparoascopic cholecystectomy between low-pressure and standard-pressure pneumoperitoneum

INTRODUCTION

Laparoscopic cholecystectomy (LC) has become the gold-standard treatment for gallstone diseases. However, despite huge reduction in operative injury, systemic stress response remains high. This randomized controlled trial (RCT) aimed to compare systemic stress response between 2 different techniques of CO2 pneumoperitoneum.

METHODS

Trough a prospective, double-blinded RCT, serum levels of cortisol, adrenaline, glucose, and C-reactive protein (CRP) were compared between the two groups consisted of 50 patients undergoing LC under low-pressure and standard-pressure CO2 pneimoperitoneum.

RESULTS

A total of fifty patients undergoing LC were equally assigned to 2 groups of twenty five patients. Average age was 48 ± 13.8 years (range, 19-74 years). Operative time was similar between standard-pressure group (47.8 ± 16.8 min) and low-pressure group (53.6 ± 25.1). Moreover, intra-operative IV volume administration and urine output did not differ significantly between the 2 groups (p > 0.05). Although the average heart rate and mean arterial pressure were slightly higher in a standard-pressure group compared with a low-pressure group, serial measurements of these parameters were statistically similar between the 2 groups. Serial changes of serum levels of cortisol, glucose, adrenaline, and CRP were compared between surgery day, postoperative 6-h and 1st postoperative day, which did not differ significantly between the standard-pressure and the low-pressure groups (p > 0.05).

CONCLUSION

Our study did not reveal any alteration in systemic stress response with reduction in intra-abdominal pressure of pneumoperitoneum in LC. RCT REGISTRATION: irct.ir ID: IRCT201110072982N5.

Effect of various pneumoperitoneum pressures on femoral vein hemodynamics during laparoscopic cholecystectomy

High intra-abdominal pressure and reverse Trendelenburg position during laparoscopic cholecystectomy (LC) are risk factors for venous stasis in lower extremity. Lower limb venous stasis is one of the major pathophysiological elements involved in the development of peri-operative deep vein thrombosis. Low pressure pneumoperitoneum (7-10 mmHg) has been recommended in patients with limited cardiac, pulmonary or renal reserve. The purpose of this study was to observe the effect of various pneumoperitoneum pressures on femoral vein (FV) hemodynamics during LC. A total of 50 patients undergoing elective LC were enrolled and they were prospectively randomized into two groups containing 25 patients each. In group A high pressure pneumoperitoneum (14 mmHg) and in group B low pressure pneumoperitoneum (8 mmHg) was maintained. Comparison of pre-operative and post-operative coagulation profile was done. Preoperative and intraoperative change in femoral vein diameter (FVD) (AP and LAT), cross-sectional area (CSA) and peak systolic flow (PSF) during varying pneumoperitoneum pressure was recorded in FV by ultrasound Doppler. First measurement (pre-operative) was carried out just after the induction of anesthesia before creation of pneumoperitoneum and second measurement (intra-operative) was taken just before completion of surgery with pneumoperitoneum maintained. Changes in coagulation parameters were less significant at low pressure pneumoperitoneum. There was statistical significant difference in the pre-operative and intra-operative values of FVD, CSA and PSF in both groups when analyzed independently (P = 0.00). There was no significant difference in pre-operative values of FVD, CSA and PSF (P > 0.05) among two groups but when the comparison was made between the intra-operative values, there was significant increase in FVD (AP) (P = 0.016), CSA (P = 0.00) and decrease in PSF (P = 0.00) at high pressure pneumoperitoneum. This study provides evidence of using low pressure pneumoperitoneum during LC as changes in FV hemodynamics and coagulation parameters were less pronounced at low pressure pneumoperitoneum.

The Effects of Volume-Controlled and Pressure-Controlled Ventilation on Lung Mechanics, Oxidative Stress, and Recovery in Gynecologic Laparoscopic Surgery

STUDY OBJECTIVE

To compare ventilation variables, changes in oxidative stress, and the quality of recovery in 2 different ventilation strategies (volume-controlled ventilation [VCV] and pressure-controlled ventilation [PCV]) during gynecologic laparoscopic surgery.

DESIGN

A prospective randomized controlled trial (Canadian Task Force classification I).

SETTING

One university teaching hospital in Taiwan.

PATIENTS

Women scheduled for laparoscopic gynecologic surgery.

INTERVENTIONS

Women were randomly assigned to receive either VCV or PCV during surgery.

MEASUREMENTS AND MAIN RESULTS

Ventilation variables were recorded 1 minute before and 1 hour after pneumoperitoneum. Blood samples were collected for malondialdehyde measurement at 7 points: 1 minute before and 1 hour after pneumoperitoneum; 30, 60, 90, and 120 minutes after deflation; and 24 hours after surgery. Postoperative recovery was assessed by using a 9-item quality of recovery score at 24 hours after surgery. A total of 52 women randomly allocated to the VCV (n = 27) or PCV (n = 25) group completed the study. We found that after 1 hour of insufflation the PCV group had lower peak airway pressure (22.0 ± 3.4 vs 26.6 ± 4.1 cm H2O, p < .0001) and higher compliance (28.4 ± 3.7 vs 24.1 ± 3.3 mL/cm H2O, p < .0001) than the VCV group. In plasma levels of malondialdehyde, there were no significant differences between the 2 groups at 7 time points. The levels significantly increased in both groups after 1 hour of pneumoperitoneum and peaked at 2 hours after deflation. During postoperative recovery, lower scores were obtained at 24 hours after surgery compared with preoperative scores, but there were no significant differences between the 2 groups.

CONCLUSION

PCV is an alternative ventilation mode in gynecologic laparoscopic surgery. However, PCV offered lower peak airway pressure and higher compliance than VCV but no advantages over VCV in oxidative stress or quality of recovery.

Effect of Pneumoperitoneum on Oxidative Stress and Inflammation via the Arginase Pathway in Rats

PURPOSE

Oxidative stress during CO₂ pneumoperitoneum is reported to be associated with decreased bioactivity of nitric oxide (NO). However, the changes in endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and arginase during CO₂ pneumoperitoneum have not been elucidated.

MATERIALS AND METHODS

Thirty male Sprague-Dawley rats were randomized into three groups. After anesthesia induction, the abdominal cavities of the rats of groups intra-abdominal pressure (IAP)-10 and IAP-20 were insufflated with CO₂ at pressures of 10 mm Hg and 20 mm Hg, respectively, for 2 hours. The rats of group IAP-0 were not insufflated. After deflation, plasma NO was measured, while protein expression levels and activity of eNOS, iNOS, arginase (Arg) I, and Arg II were analyzed with aorta and lung tissue samples.

RESULTS

Plasma nitrite concentration and eNOS expression were significantly suppressed in groups IAP-10 and IAP-20 compared to IAP-0. While expression of iNOS and Arg I were comparable between the three groups, Arg II expression was significantly greater in group IAP-20 than in group IAP-0. Activity of eNOS was significantly lower in groups IAP-10 and IAP-20 than in group IAP-0, while iNOS activity was significantly greater in group IAP-20 than in groups IAP-0 and IAP-10. Arginase activity was significantly greater in group IAP-20 than in groups IAP-0 and IAP-10.

CONCLUSION

The activity of eNOS decreases during CO₂ pneumoperitoneum, while iNOS activity is significantly increased, a change that contributes to increased oxidative stress and inflammation. Moreover, arginase expression and activity is increased during CO₂ pneumoperitoneum, which seems to act inversely to the NO system.

Humidification during laparoscopic surgery: overview of the clinical benefits of using humidified gas during laparoscopic surgery

PURPOSE

The peritoneum is the serous membrane that covers the abdominal cavity and most of the intra-abdominal organs. It is a very delicate layer highly susceptible to damage and it is not designed to cope with variable conditions such as the dry and cold carbon dioxide (CO2) during laparoscopic surgery. The aim of this review was to evaluate the effects caused by insufflating dry and cold gas into the abdominal cavity after laparoscopic surgery.

METHODS

A literature search using the Pubmed was carried out. Articles identified focused on the key issues of laparoscopy, peritoneum, morphology, pneumoperitoneum, humidity, body temperature, pain, recovery time, post-operative adhesions and lens fogging.

RESULTS

Insufflating dry and cold CO2 into the abdomen causes peritoneal damage, post-operative pain, hypothermia and post-operative adhesions. Using humidified and warm gas prevents pain after surgery. With regard to hypothermia due to desiccation, it can be fully prevented using humidified and warm gas. Results relating to the patient recovery are still controversial.

CONCLUSIONS

The use of humidified and warm insufflation gas offers a significant clinical benefit to the patient, creating a more physiologic peritoneal environment and reducing the post-operative pain and hypothermia. In animal models, although humidified and warm gas reduces post-operative adhesions, humidified gas at 32 °C reduced them even more. It is clear that humidified gas should be used during laparoscopic surgery; however, a question remains unanswered: to achieve even greater clinical benefit to the patient, at what temperature should the humidified gas be when insufflated into the abdomen? More clinical trials should be performed to resolve this query.

The Effect of Intraoperative N-Acetylcysteine on Hepatocellular Injury During Laparoscopic Bariatric Surgery. A Randomised Controlled Trial

BACKGROUND

The combination of pneumoperitoneum and intraoperative retraction of the left lobe of the liver leads to hepatocellular injury during laparoscopic gastric surgery. Fatty livers are more susceptible to ischaemic insults. This trial investigated whether the antioxidant N-acetylcysteine (NAC) reduced liver injury during laparoscopic sleeve gastrectomy (LSG).

METHODS

Patients undergoing LSG were randomised (single blinded) to receive intraoperative NAC infusion or standard anaesthetic treatment. Blood samples were taken before and after surgery (days 0 to 4). Primary endpoints included serum aminotransferases. Secondary measures were C-reactive protein, weight cell count (WCC), cytokines (interleukin 6 and 10) and cytokeratin-18 as markers of apoptosis. Intraoperative liver biopsy samples were assessed using a locally developed injury score.

RESULTS

Twenty patients (14 females, mean age 44.5 (SEM ± 2.9) years, mean BMI 60.8 (SEM ± 2.4) kg/m(2)) were recruited (NAC n = 10, control n = 10). The trial was stopped early after a planned interim analysis. Baseline liver function was similar. The peak rise in liver enzymes was on day 1, but levels were not significantly different between the groups. Rates of complications and length of stay were not significantly different. Secondary outcome measures, including white cell count (WCC), cytokines and cytokeratin (CK)-18 fragments, were not different between groups. Liver injury scores did not differ significantly.

CONCLUSIONS

NAC did not reduce intraoperative liver injury in this small number of patients. The heterogenous nature of the study population, with differences in co-morbidities, body mass index and intraabdominal anatomy, leads to a varied post-operative inflammatory response. Significant hepatocyte injury occurs through both necrosis and apoptosis.

Attenuation of Oxidative Stress by Ischemic Preconditioning in an Experimental Model of Intraabdominal Hypertension

PURPOSE

Increased intra-abdominal pressure, as used in laparoscopic surgery or seen in intraabdominal hypertension (IAH), is associated with tissue ischemia and oxidative stress. Ischemic preconditioning (IP) is a method successfully used in liver and transplant surgery, in order to attenuate the detrimental effects of ischemia and reperfusion. In this experimental study, we tested the ability of IP to modify oxidative stress induced by extremely high intraabdominal pressures.

METHODS

Twenty-five female pigs were studied and divided in three groups: a control group, a pneumoperitoneum group (with pressure of 30 mmHg), and an ischemic preconditioning group (initially subjected to preconditioning with pressure of 25 mmHg for 15 min and desufflation for 15 min and then to pneumoperitoneum as in pneumoperitoneum group). Blood samples were obtained at identical time intervals in the three groups. Total oxidative capacity, total antioxidative capacity and total nitric oxide (NO), nitrite and nitrate concentrations were measured and compared between groups.

RESULTS

IP increased total antioxidative capacity (p = .045) and protective mediators like nitrite (p = .022). It was also associated with a trend toward lower levels of total oxidative capacity at the end of the abdominal desufflation period but statistical significance was not met.

CONCLUSIONS

IP attenuated oxidative stress induced by IAH, mainly by increasing antioxidative capacity and the levels of protective mediators. The fact that IP was effective, even when used at extremely high levels of intraabdominal pressure, reinforces the interest on this method but further studies are needed to clarify its mechanism of action and potential clinical applications.