Stepwise Rising CO2Insufflation as an Ischemic Preconditioning Method

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.

The "Dark Side" of Pneumoperitoneum and Laparoscopy

Laparoscopic surgery has been one of the most common procedures for abdominal surgery at pediatric age during the last few decades as it has several advantages compared to laparotomy, such as shorter hospital stays, less pain, and better cosmetic results. However, it is associated with both local and systemic modifications. Recent evidence demonstrated that carbon dioxide pneumoperitoneum might be modulated in terms of pressure, duration, temperature, and humidity to mitigate and modulate these changes. The aim of this study is to review the current knowledge about animal and human models investigating pneumoperitoneum-related biological and histological impairment. In particular, pneumoperitoneum is associated with local and systemic inflammation, acidosis, oxidative stress, mesothelium lining abnormalities, and adhesion development. Animal studies reported that an increase in pressure and time and a decrease in humidity and temperature might enhance the rate of comorbidities. However, to date, few studies were conducted on humans; therefore, this research field should be further investigated to confirm in experimental models and humans how to improve laparoscopic procedures in the spirit of minimally invasive surgeries.

Pneumoperitoneum Modifies Serum and Tissue CCL2-CCL5 Expression in Mice

Background and Objectives:

Laparoscopy is the preferred method when operating in the abdomen. In this study, we evaluated systemic and morphological peritoneal cytokine modifications (RANTES/CCL5 and MCP-1/CCL2) due to CO₂ pneumoperitoneum in rats.

Methods:

Twenty-five prepubertal Sprague-Dawley rats were randomized into three groups. Pneumoperitoneum lasting 30 minutes, was induced with a flow of 0.5 L/min, in two groups (S1 and S2, n = 20), at a P/CO₂ of 6 and 10 mm Hg, respectively. In the control group (C, n = 5), only anesthesia was carried out. All animals were sacrificed after 24 hours. The serum of the rats was collected for ELISA, and the levels of the cytokines RANTES and MCP-1 were investigated. An immunohistochemical analysis of RANTES and MCP-1 was performed on samples of the peritoneum, and the morphological evaluation was conducted with a blinded evaluation by two independent, experienced pathologists by using a grading system (0, 1+, 2+, 3+: no, faint, moderate, and strong reactivity, respectively).

Results:

RANTES mean levels were significantly different in the S1, S2, and C groups (70.3 ± 2.26, 58.23 ± 4.32, 29.66 ± 4.03, respectively, P = .0001). The levels of MCP-1 were 32.1 ± 1.63 in the S1 group, 27.0 ± 9.26 in the S2 group, and 16.4 ± 9.55 in the C group (P = .159). Normal control peritoneum showed little reactivity, whereas a moderate to strong cytoplasmic reaction to anti-CCL5/CCL2 antibodies was observed in mesothelial and inflammatory cells in the S1 and S2 groups.

Conclusion:

CO₂ pneumoperitoneum evokes an inflammatory response by modifying plasma RANTES levels and peritoneal CCL5/CCL2 expression.

Ventilation and outcomes following robotic-assisted abdominal surgery: an international, multicentre observational study

BACKGROUND

International data on the epidemiology, ventilation practice, and outcomes in patients undergoing abdominal robotic-assisted surgery (RAS) are lacking. The aim of the study was to assess the incidence of postoperative pulmonary complications (PPCs), and to describe ventilator management after abdominal RAS.

METHODS

This was an international, multicentre, prospective study in 34 centres in nine countries. Patients ≥18 yr of age undergoing abdominal RAS were enrolled between April 2017 and March 2019. The Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) score was used to stratify for higher risk of PPCs (≥26). The primary outcome was the incidence of PPCs. Secondary endpoints included the preoperative risk for PPCs and ventilator management.

RESULTS

Of 1167 subjects screened, 905 abdominal RAS patients were included. Overall, 590 (65.2%) patients were at increased risk for PPCs. Meanwhile, 172 (19%) patients sustained PPCs, which occurred more frequently in 132 (22.4%) patients at increased risk, compared with 40 (12.7%) patients at lower risk of PPCs (absolute risk difference: 12.2% [95% confidence intervals (CI), 6.8-17.6%]; P<0.001). Plateau and driving pressures were higher in patients at increased risk, compared with patients at low risk of PPCs, but no ventilatory variables were independently associated with increased occurrence of PPCs. Development of PPCs was associated with a longer hospital stay.

CONCLUSIONS

One in five patients developed one or more PPCs (chiefly unplanned oxygen requirement), which was associated with a longer hospital stay. No ventilatory variables were independently associated with PPCs.

CLINICAL TRIAL REGISTRATION

NCT02989415.

International multicenter observational study on assessment of ventilatory management during general anaesthesia for robotic surgery and its effects on postoperative pulmonary complication (AVATaR): study protocol and statistical analysis plan

INTRODUCTION

Robotic-assisted surgery (RAS) has emerged as an alternative minimally invasive surgical option. Despite its growing applicability, the frequent need for pneumoperitoneum and Trendelenburg position could significantly affect respiratory mechanics during RAS. AVATaR is an international multicenter observational study aiming to assess the incidence of postoperative pulmonary complications (PPC), to characterise current practices of mechanical ventilation (MV) and to evaluate a possible association between ventilatory parameters and PPC in patients undergoing RAS.

METHODS AND ANALYSIS

AVATaR is an observational study of surgical patients undergoing MV for general anaesthesia for RAS. The primary outcome is the incidence of PPC during the first five postoperative days. Secondary outcomes include practice of MV, effect of surgical positioning on MV, effect of MV on clinical outcome and intraoperative complications.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Board of the Hospital Israelita Albert Einstein. The study results will be published in peer-reviewed journals and disseminated at international conferences.

TRIAL REGISTRATION NUMBER

NCT02989415; Pre-results.

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.

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.

Impact of a lung-protective ventilatory strategy on systemic and pulmonary inflammatory responses during laparoscopic surgery: is it really helpful?

Laparoscopic surgery is performed by carbon dioxide (CO2) insufflation, but this may induce stress responses. The aim of this study is to compare the level of inflammatory mediators in patients receiving low tidal volume (VT) versus traditional VT during gynecological laparoscopic surgery. Forty American Society of Anesthesiologists (ASA) physical status 1 and 2 subjects older than 18 years old undergoing laparoscopic gynecological surgery were included. Systemic inflammatory response was assessed with serum IL-6, TNF-alpha, IL-8, and IL-1β in patients receiving intraoperative low VT and traditional VT during laparoscopic surgery [within the first 5 min after endotracheal intubation (T1), 60 min after the initiation of mechanical ventilation (T2), and in the postanesthesia care unit 30 min after tracheal extubation (T3)]. Additionally, inflammatory response was assessed with bronchoalveolar lavage (BAL) at T1 and T3 periods. An increase in the serum levels of IL-6, TNF-alpha, IL-8, and IL-1β was observed in both groups during the time periods of T1, T2, and T3. No significant differences were found in the serum and BAL levels of inflammatory mediators during time periods between groups. The results of the present study suggested that the lung-protective ventilation and traditional strategies are not different in terms of lung injury and inflammatory response during conventional laparoscopic gynecological surgery.

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.

Optimizing working space in laparoscopy: CT measurement of the influence of small body size in a porcine model

INTRODUCTION

In our continuing research into the determinants of laparoscopic working space, the influence of small body size was investigated.

METHODS

In eight 6-kg pigs, the effects of intraabdominal CO2 pneumoperitoneum pressure (IAP), prestretching of the abdominal wall, and neuromuscular blockade (NMB) on laparoscopic working space volume and distances were studied. Computed tomography was used to measure working space during two stepwise abdominal insufflation-runs up to an IAP of 15mm Hg. Results were compared with data from earlier experiments in 20-kg pigs.

RESULTS

Cardiorespiratory parameters were stable up to an IAP of 8-10mm Hg. In 6-kg pigs working-space dimensions were five times smaller than in 20-kg pigs. Working-space volume, anteroposterior (AP) diameter and symphysis-diaphragm distance increased linearly up to an IAP of 8mm Hg. Above 8mm Hg, compliance decreased. Eighty percent of the total volume (618ml) and of AP diameter (3cm) at 15mm Hg had been achieved at an IAP of 10mm Hg. Prestretching by a first insufflation resulted in a statistically significant increase in working space volume and in AP diameter during the second insufflation. This effect was significantly larger than in 20-kg pigs. Neuromuscular blockade did not have a significant effect on working-space.

CONCLUSIONS

Working space in growing individuals is very limited. Eighty percent of the working space created by an IAP of 15mm Hg was already achieved at 10mm Hg, while cardiorespiratory side effects at an IAP of 8-10mm Hg seem acceptable. Prestretching of the abdominal wall significantly increased working space, even more so than in 20-kg pigs. As in 20-kg pigs, NMB had no significant effect on laparoscopic working space. Prestretching of the abdominal wall is a promising cheap, safe and easy strategy to increase laparoscopic working space, lessening the need for prolonged high-pressure pneumoperitoneum.

Does pneumoperitoneum adversely affect growth, development and liver function in biliary atresia patients after laparoscopic portoenterostomy?

PURPOSE

We assessed the effect of high partial pressure of arterial carbon dioxide (PaCO2) due to pneumoperitoneum (PP) on growth (height/weight) and development (gross/fine motor function, receptive/expressive communication, and social interaction), by comparing outcome after portoenterostomy (PE) for biliary atresia (BA) using laparoscopic PE (LPE: n = 13) and open PE (OPE: n = 13) cases performed between 2005 and 2014.

METHODS

Our PE is based on Kasai's original PE. All data were collated prospectively.

RESULTS

Differences in duration of follow-up (LPE: 38.8 months; OPE: 38.1 months), jaundice clearance (LPE: 12/13 = 92.3 %; OPE: 9/13 = 69.2 %), survival with the native liver (LPE: 10/13 = 76.9 %; OPE: 9/13 = 69.2 %), incidence of cholangitis, hypersplenism, and incidence of esophageal varices were not significant. Mean intraoperative PaCO2 was significantly higher in LPE (LPE: 50.1 mmHg; OPE: 40.7 mmHg, p < 0.05). Liver function impairment was not statistically different, although LPE results were slightly worse. There was no overall delay in growth observed, although height/weight gain was more consistent in LPE. The pattern of developmental delay observed was similar for LPE and OPE suggesting that developmental delay is not PE-related; in other words, PP is not implicated in developmental delay.

CONCLUSIONS

PP during LPE would appear to have no adverse effects on overall growth/development and liver function in BA patients.

Optimizing working space in laparoscopy: CT measurement of the effect of pre-stretching of the abdominal wall in a porcine model

BACKGROUND

Determinants of working space in minimal access surgery have not been well studied. Using computed tomography (CT) to measure volumes and linear dimensions, we are studying the effect of a number of determinants of CO2 working space in a porcine laparoscopy model. Here we report the effects of pre-stretching of the abdominal wall.

METHODS

Earlier we had noted an increase in CO2 pneumoperitoneum volume at repeat insufflation with an intra-abdominal pressure (IAP) of 5 mmHg after previous stepwise insufflation up to an IAP of 15 mmHg. We reviewed the data of this serendipity group; data of 16 pigs were available. In a new group of eight pigs, we also explored this effect at repeat IAPs of 10 and 15 mmHg. Volumes and linear dimensions of the CO2 pneumoperitoneum were measured on reconstructed CT images and compared between the initial and repeat insufflation runs.

RESULTS

Previous stepwise insufflation of the abdomen with CO2 up to 15 mmHg significantly (p < 0.01) increased subsequent working-space volume at a repeat IAP of 5 mmHg by 21 %, 7 % at a repeat IAP of 10 mmHg and 3 % at a repeat IAP of 15 mmHg. The external anteroposterior diameter significantly (p < 0.01) increased by 0.5 cm (14 %) at repeat 5 mmHg. Other linear dimensions showed a much smaller change. There was no statistically significant correlation between the duration of the insufflation run and the volume increase after pre-stretching at all IAP levels.

CONCLUSIONS

Pre-stretching of the abdominal wall allows for the same surgical-field exposure at lower IAPs, reducing the negative effects of prolonged high-pressure CO2 pneumoperitoneum on the cardiorespiratory system and microcirculation. Pre-stretching has important scientific consequences in studies addressing ways of increasing working space in that its effect may confound the possible effects of other interventions aimed at increasing working space.

Pharmacological modulation of oxidative stress response in minimally invasive surgery: systematic review

This systematic review aims to synthesize the data on the effectiveness of pharmacological modulation of stress response in minimally invasive surgery. Eligible trials were clinical trials randomized or not or experimental trials that investigated the effect of pharmacological agents on modulation of surgical stress response to minimally invasive surgery. No clinical trials were identified. Eight experimental trials met the inclusion criteria and were obtained in full text. Experimental models were rats or rabbits subjected to pneumoperitoneum, or pneumoretroperitoneum, not to a whole operation. Pharmacological modulation of surgical stress response was attempted with erythromycin, melatonin, mesna, verapamil, pentoxifylline, N-acetylcysteine, and zinc. All the pharmacological agents, except pentoxifylline, seemed to reduce oxidative stress markers. However, only mesna pretreatment prevented oxidative stress, because oxidative stress markers remained in the sham levels. Contrasting data were obtained for pentoxyphilline. In conclusion, available data suggest that pharmacological modulation of surgical stress response to minimally invasive surgery might be feasible.

Laparoscopic preconditioning protects against oxidative injury in cerulein-induced pancreatitis rats (an experimental study)

BACKGROUND

Laparoscopic cholecystectomy, particularly in the same hospital stay, has been widely recommended to treat gallstone-pancreatitis over the last decade. Although pancreatitis produces severe oxidative injury, laparoscopy exerts an additional effect over that is produced by pancreatitis. The preconditioning phenomenon previously reported as protective in open surgery is a beneficial maneuver also in laparoscopic surgery. So in the present study we have tried to find out the effect of laparoscopic preconditioning over the pancreatitis in cerulein-induced pancreatitis rats.

METHODS

Acute pancreatitis was induced in 24 rats weighing between 280 and 350 g by three subcutaneous injection of 80 μg/kg of body weight cerulein. A 1-cm midline laparotomy was performed for all rats, and then they were randomly assigned to one of the following three groups (n=8 for each): Group I (control), Group II (laparoscopy), and Group III (laparoscopic preconditioning [L-Pre]). After that, a catheter was placed into the peritoneum for the creation of the pneumoperitoneum (Pp) in all the animals except the control group. The rats of Groups II and III were subjected to 60 minutes of Pp with 15 mm Hg intraabdominal pressure followed by 30 minutes of deflation. The L-Pre procedure was applied to Group III immediately before the laparoscopic procedure. Blood samples were taken for biochemical assays. Pancreas tissue samples were taken for light microscope analysis.

RESULTS

The light microscopy of the pancreas tissues revealed that cerulein injection caused edema and sparse inflammatory cell infiltration mimicking the edematous pancreatitis. However, the application of laparoscopy over the pancreatitis produced significant inflammatory cell infiltration, acinus vacuolization, and necrosis (in one case) in addition to edema. But, the laparoscopic preconditioning maneuver applied before the laparoscopy significantly decreased in particular acinary vacuolization and cell infiltration. Therefore the total sum of the histopathological score of the L-Pre group was significantly less than that of the laparoscopy group. The biochemical analysis of the groups revealed that laparoscopy caused significant elevation of malondialdehyde levels and decrease of reduced glutathione values. However, the addition of preceding preconditioning produced significant amelioration of these parameters.

CONCLUSION

Laparoscopic preconditioning may be a useful method to decrease the oxidative injury in cases undergoing cholecystectomy for biliary pancreatitis. But, it should be emphasized that this was a restricted experimental study, and further clinical studies are needed to adopt these results into clinical settings.

Two clinically relevant pressures of carbon dioxide pneumoperitoneum cause hepatic injury in a rabbit model

AIM: To observe the hepatic injury induced by carbon dioxide pneumoperitoneum (CDP) in rabbits, compare the effects of low- and high-pressure pneumoperitoneum, and to determine the degree of hepatic injury induced by these two clinically relevant CDP pressures.

METHODS: Thirty healthy male New Zealand rabbits weighing 3.0 to 3.5 kg were randomly divided into three groups (n = 10 for each group) and subjected to the following to CDP pressures: no gas control, 10 mmHg, or 15 mmHg. Histological changes in liver tissues were observed with hematoxylin and eosin staining and transmission electron microscopy. Liver function was evaluated using an automatic biochemical analyzer. Adenine nucleotide translocator (ANT) activity in liver tissue was detected with the atractyloside-inhibitor stop technique. Bax and Bcl-2 expression levels were detected by western blotting.

RESULTS: Liver functions in the 10 mmHg and 15 mmHg experimental groups were significantly disturbed compared with the control group. After CDP, the levels of alanine transaminase and aspartate transaminase were 77.3 ± 14.5 IU/L and 60.1 ± 11.4 IU/L, respectively, in the 10 mmHg experimental group and 165.1 ± 19.4 IU/L and 103.8 ± 12.3 IU/L, respectively, in the 15 mmHg experimental group, which were all higher than those of the control group (P < 0.05). There was no difference in pre-albumin concentration between the 10 mmHg experimental group and the control group, but the pre-albumin level of the 15 mmHg experimental group was significantly lower than that of the control group (P < 0.05). No significant differences were observed in the levels of total bilirubin or albumin among the three groups. After 30 and 60 min of CDP, pH was reduced (P < 0.05) and PaCO₂ was elevated (P < 0.05) in the 10 mmHg group compared with controls, and these changes were more pronounced in the 15 mmHg group. Hematoxylin and eosin staining showed no significant change in liver morphology, except for mild hyperemia in the two experimental groups. Transmission electron microscopy showed mild mitochondrial swelling in hepatocytes of the 10 mmHg group, and this was more pronounced in the 15 mmHg group. No significant difference in ANT levels was found between the control and 10 mmHg groups. However, ANT concentration was significantly lower in the 15 mmHg group compared with the control group. The expression of hepatic Bax was significantly increased in the two experimental groups compared with the controls, but there were no differences in Bcl-2 levels among the three groups. Twelve hours after CDP induction, the expression of hepatic Bax was more significant in the 15 mmHg group than in the 10 mmHg group.

CONCLUSION: A CDP pressure of 15 mmHg caused more substantial hepatic injury, such as increased levels of acidosis, mitochondrial damage, and apoptosis; therefore, 10 mmHg CDP is preferable for laparoscopic operations.

Antioxidant prophylaxis for cellular injury in ovarian surface epithelium resulting from CO₂ pneumoperitoneum in a laparoscopic rat model

OBJECTIVE

Selective cytoprotective functions of vitamin E, N-acetyl-L: -cysteine, and amifostine have been used as a preventer of ischemia injury by expelling the free oxygen radicals leading to stabilization of the cellular membranes. The purpose of this experimental study was to investigate the oxidative stress related to cellular injury in ovarian surface epithelium and the effect of prophylaxis with an anti-oxidant using laparoscopic rat model.

DESIGN

Laparoscopic rat model.

MATERIALS AND METHODS

Randomly allocated 40 Wistar Albino female rats have been used for the pneumoperitoneum model which was constituted to fix the intraabdominal pressure on 5 mmHg for 60 min. The antioxidants, vitamin E and NAC were given to rats 3 days before the operation and were applied for 30 days; amifostine was applied 30 min before the operation until after for 7 days. After abdominal desufflation, over biopsies were made on the 13th min, 24th h, and 7th and 30th days. By using of transmission electron microscopy, the damage on cells and organels were assessed and graded.

RESULTS

In ovarian surface epithelium, the apical surface specializations were affected in all groups except Vit E group:The microvilli were irregular and coarse and had disappeared in some places. Some cells were separated from the epithelium. In addition, mitochondria degeneration was observed in all group except Vit E.

CONCLUSIONS

In the early period of laparoscopy, reversible cellular damage occurs and this damage can be prevented by vitamin E.

Warming and humidification have no effect on oxidative stress during pneumoperitoneum in rats

Pneumoperitoneum is reported to induce oxidative stress due to the desiccative effect of cold, dry gas insufflation. The aim of this study is to compare the effect of warmed, humidified insufflation to standard gas, by measuring oxidative stress markers in a physiologically relevant animal model. Twenty male Wistar rats (330?650 g) were alternately assigned to the Warm Humidified group (WH, n = 10) and Control group (n = 10). All rats underwent pneumoperitoneum at 5 mmHg and a controlled flow rate for 110 min. The WH group received warmed (37?C) and humidified (98% Relative Humidity (RH)) gas and the control group received standard gas at room temperature (19?C) and 0% RH. At the end of pneumoperitoneum, samples of liver, kidney, pancreas, jejunum, and lung were excised. Levels of plasma and tissue malondialdehyde (MDA) and protein carbonyls (PC) were measured. Organ light microscopy was performed. There were no differences between groups for MDA or PC concentrations in plasma, liver, kidney, jejunum, or lung tissue. There were no differences in histological score between groups. Warming and humidification of pneumoperitoneum insufflation gas have no effect on measures of oxidative stress compared to non-warmed, non-humidified controls.

Preconditioning is a method that may reduce the negative side-effect of pneumoperitoneum

Increased intra-abdominal pressure during laparoscopy leads to hypoxia due to reduced blood flow. Aim of our study was to investigate whether preconditioning can reduce this negative effect of the pneumoperitoneum. Fifty female Wistar rats were used, divided into 5 groups. I: Sham operation (Sham), II: conventional pneumoperitoneum (PP), III: transvaginal pneumoperitoneum (TV), IV: preconditioning for 2.5 minutes in two cycles (Pre 2.5), V: preconditioning for 5 minutes (Pre 5). Malondialdehyde (MDA), reduced glutathione (GSH), sulfhydrylgroup (SH-) concentrations, superoxide-dismutase (SOD) and mieloperoxidase (MPO) activity, and anti-apoptotic pathway marker p-AKT level and inflammatory cytokine TNF-α were measured. SOD activity and GSH concentration were decreased in PP and TV groups comparing to Sham and preconditioning groups. MPO activity was decreased also in PP and TV groups comparing to the Sham group but in the preconditioning groups it has remained high. MDA concentration in plasma was increased in PP and TV groups comparing to Sham and preconditioning groups. There was no difference in the case of blood MDA and SH-concentrations between groups. Anti-apoptotic pathway marker p-AKT level was decreased in the TV group comparing to the sham and preconditioning groups. TNF-α level was increased in TV and preconditioning groups compared to the sham group. According to the results preconditioning can reduce negative effects of pneumoperitoneum.

Peritoneal damage: the inflammatory response and clinical implications of the neuro-immuno-humoral axis

BACKGROUND

The peritoneum is a bilayer serous membrane that lines the abdominal cavity. We present a review of peritoneal structure and physiology, with a focus on the peritoneal inflammatory response to surgical injury and its clinical implications.

METHODS

We conducted a nonsystematic clinical review. A search of the Ovid MEDLINE database from 1950 through January 2009 was performed using the following search terms: peritoneum, adhesions, cytokine, inflammation, and surgery.

RESULTS

The peritoneum is a metabolically active organ, responding to insult through a complex array of immunologic and inflammatory cascades. This response increases with the duration and extent of injury and is central to the concept of surgical stress, manifesting via a combination of systemic effects, and local neural pathways via the neuro-immuno-humoral axis. There may be a decreased systemic inflammatory response after minimally invasive surgery; however, it is unclear whether this is due to a reduced local peritoneal reaction.

CONCLUSIONS

Interventions that dampen the peritoneal response and/or block the neuro-immuno-humoral pathway should be further investigated as possible avenues of enhancing recovery after surgery, and reducing postoperative complications.

What should be the ideal time for ischemic preconditioning in a laparoscopic rat model?

BACKGROUND

Pneumoperitoneum (Pp) induces an ischemia and reperfusion (I/R) injury as a result of released oxidative stress markers. Ischemic preconditioning (IP) is one of the used methods to reduce the harmful effects of Pp, which is a mechanism for reducing organ I/R injury by a brief period of organ ischemia. The aim of this study was to investigate the ideal time for IP in the laparoscopic model.

METHODS

Thirty-two rats were assigned into four groups: group 1 (control, n = 8) was subjected to a sham operation. Group 2 (5-minutes IP, n = 8) was subjected to 5 minutes of Pp with 15 mm Hg of pressure followed immediately by 5 minutes of deflation, and after that, 60 minutes of Pp with 15 mm Hg, followed by 60 minutes of deflation. Group 3 (10-minutes IP, n = 8) was subjected to 10 minutes of Pp and 10 minutes of deflation. Group 4 (Pp only, n = 8) was subjected to 60 minutes of Pp with 15 mm Hg of pressure, followed by 60 minutes of deflation. At the end of the experiment, plasma malondialdehyde (MDA) values, the oxidative stress marker, and plasma-reduced glutathione (GSH) levels, the marker showing antioxidant activity, were determined.

RESULTS

Highest plasma MDA values were in group 4 (Pp only), followed by groups 2 and 3 and group 1 (P = 0.181). In addition, IP groups had almost the same values for MDA. Plasma GSH levels in the control group were significantly higher than those in the IP groups and the Pp-only group (P < 0.001). Similarly, as in MDA levels, no difference was found between plasma GSH levels of the IP 5-minutes and IP 10-minutes groups.

CONCLUSIONS

Five minutes of the IP model may be as reliable as 10 minutes of the IP model. In that case, 5 minutes of IP can be more suitable in reducing I/R injury in laparoscopy.

Systematic review of oxidative stress associated with pneumoperitoneum

Background

There have been several reports of ischaemic complications after routine laparoscopy. The aim of this review was to investigate the relationship between this oxidative stress and pneumoperitoneum.

Methods

Medline, Medline in-process, The Cochrane Library, PubMed and EMBASE were searched for papers on oxidative stress and pneumoperitoneum, from 1947 to March 2008 with no language restriction or restriction on trial design. Papers that did not investigate pneumoperitoneum as a causative factor, or did not report outcome measures related to oxidative stress, were excluded.

Results

A total of 73 relevant papers were identified: 36 animal studies, 21 human clinical trials, nine case reports, five review articles and two comments. Pneumoperitoneum causes a reduction in splanchnic blood flow, resulting in biochemical evidence of oxidative stress in a pressure- and time-dependent manner. There is evidence that the use of carbon dioxide for insufflation is contributory. Several measures proposed to minimize the oxidative stress have shown promise in animal studies, but few have been evaluated in the clinical setting.

Conclusion

There is an increasing body of evidence, mainly from animal studies, that pneumoperitoneum decreases splanchnic perfusion with resulting oxidative stress. It is now appropriate to investigate the clinical significance of pneumoperitoneum-associated oxidative stress.

Hepatic injury induced by carbon dioxide pneumoperitoneum in experimental rats

AIM: To observe the hepatic injury induced by carbon dioxide pneumoperitoneum in rats and to explore its potential mechanism.

METHODS: Thirty healthy male SD rats were randomly divided into control group (n = 10), 0 h experimental group (n = 10) and 1 h experimental group (n = 10) after sham operation with carbon dioxide pneumoperitoneum. Histological changes in liver tissue were observed with hematoxylin-eosin staining. Liver function was assayed with an automatic biochemical analyzer. Concentration of malonyldialdehyde (MDA) and activity of superoxide dismutase (SOD) were assayed by colorimetry. Activity of adenine nucleotide translocator in liver tissue was detected with the atractyloside-inhibitor stop technique. Expression of hypoxia inducible factor-1 (HIF-1) mRNA in liver tissue was detected with in situ hybridization.

RESULTS: Carbon dioxide pneumoperitoneum for 60 min could induce liver injury in rats. Alanine aminotransferase and aspartate aminotransferase were 95.7 ± 7.8 U/L and 86.8 ± 6.9 U/L in 0 h experimental group, and 101.4 ± 9.3 U/L and 106.6 ± 8.7 U/L in 1 h experimental group. However, no significant difference was found in total billirubin, albumin, and pre-albumin in the three groups. In 0 h experimental group, the concentration of MDA was 9.83 ± 2.53 &mgr;mol/g in liver homogenate and 7.64 ± 2.19 &mgr;mol/g in serum respectively, the activity of SOD was 67.58 ± 9.75 nu/mg in liver and 64.47 ± 10.23 nu/mg in serum respectively. In 1 h experimental group, the concentration of MDA was 16.57 ± 3.45 &mgr;mol/g in liver tissue and 12.49 ± 4.21 &mgr;mol/g in serum respectively, the activity of SOD was 54.29 ± 7.96 nu/mg in liver tissue and 56.31 ± 9.85 nu/mg in serum, respectively. The activity of ANT in liver tissue was 9.52 ± 1.56 in control group, 6.37 ± 1.33 in 0 h experimental group and 7.28 ± 1.45 (10^-9 mol/min per gram protein) in 1 h experimental group, respectively. The expression of HIF-1 mRNA in liver tissue was not detected in control group, and its optical density difference value was 6.14 ± 1.03 in 0 h experimental group and 9.51 ± 1.74 in 1 h experimental group, respectively.

CONCLUSION: Carbon dioxide pneumoperitoneum during the sham operation can induce hepatic injury in rats. The probable mechanisms of liver injury include anoxia, ischemia reperfusion and oxidative stress. Liver injury should be avoided during clinical laparoscopic operation with carbon dioxide pneumoperitoneum.