Effect Of Carbon Dioxide Pneumoperitoneum Research Articles

A STUDY OF ALTERATION IN COAGULATION PROFILE IN PATIENTS UNDERGOING LAPAROSCOPIC CHOLECYSTECTOMY

Introduction: Laparoscopic cholecystectomy has become the gold standard for the treatment of cholelithiasis. It has many advantages such as better cosmetic, shorter hospitalization time, minimal postoperative pain, early return to normal life. However carbon dioxide pneumoperitoneum may cause alteration in the coagulation system and moreover the reverse Trendelenburg position adopted diring surgery can induce blood stagnation in the lower limbs leading to a hypercoagulable state. The aim Objective: of the study was to record the effect of carbon dioxide pneumoperitoneum on coagulation factors and brinolysis response during laparoscopic cholecystectomy and to assess if there is any risk of postoperative thromboembolic complications following laparoscopic cholecystectomy. Methods: The hospital based descriptive study of 50 patients undergoing elective laparoscopic cholecystectomy was designed to study alteration in Clotting time, Prothrombin time(PT), Activated partial thrombin time(aPTT), Fibrinogen and D-dimer, which were measured preoperatively and 6 hour postoperatively. Out of 50 Results: patients operated 38 were female and 12 were male. Signicant decrease in PT and aPTT suggested activation of coagulation pathways while signicant increase in d-dimer and brinogen suggested activation of brinolytic systems. None of the patients had any postoperative thromboembolic complications. From the study we found that there was activati Discussions: on of coagulation and brinolysis after laparoscopic cholecystectomy leading to a hypercoagulable state which may be either due to carbon dioxide pneumoperitoneum or due to increased intraabdominal pressure. Although none of the patients had any thromboembolic complications postoperatively, however there may be the need to use prophylactic measures for thrombosis in high risk patients.

Effect of carbon dioxide pneumoperitoneum on acid-base balance during laparoscopic inguinal hernia repair: a prospective randomized controlled study.

In this study, we aimed to compare the effects of CO2 pneumoperitoneum on acid-base balance during transabdominal preperitoneal (TAPP) and total extraperitoneal (TEP) procedures for repair of inguinal hernias. The study cohort comprised 100 patients who underwent repair of primary inguinal hernias from 1 June to 30 November 2019. The patients were randomly allocated to TAPP and TEP groups. Their acid-base balance was analyzed by comparing the results of blood gas analysis before and after the operative procedures and dynamic transcutaneous CO2 (TcCO2) changes during the procedures. There were no statistically significant differences among groups in demographics, including sex, age, and hernia type. There were also no significant differences between the two groups in anesthesia time, incidence of perioperative complications, or type of management of the hernia sac (all P > 0.05). The operation time was shorter for the TEP than the TAPP group (P < 0.01). In terms of CO2 metabolism and acid-base balance, the following differences between the two groups were statistically significant: changes in PaCO2 (7.54 ± 3.36 vs. 20.36 ± 7.60mmHg, P < 0.01), changes in TcCO2 (8.86 ± 3.57 vs. 17.40 ± 8.03mmHg, P < 0.01), rate of change in TcCO2 (0.22 ± 0.11 vs. 1.03 ± 0.56, P < 0.01), and changes in pH (- 0.05 ± 0.28 vs. - 0.15 ± 0.76, P < 0.01). TAPP and TEP can achieve good results in the treatment of inguinal hernia. Although no serious complications occurred, TEP procedures may cause more serious CO2 accumulation and quicker acidosis than TAPP procedures.

Effect of carbon dioxide pneumoperitoneum on acid base balance during laparoscopic surgeries

Effect of carbon dioxide pneumoperitoneum on acid base balance during laparoscopic surgeries

Evaluation of robot-assisted laparoscopic versus open cystectomy and effect of carbon dioxide-pneumoperitoneum on histopathological findings in ureteroenteric anastomoses: results from an experimental randomized porcine study

Objective: The aim of this study was to investigate the histopathology of ureteroenteric anastomoses (UEAs) after radical cystectomy (RC) with an ileal conduit in a porcine model using different surgical techniques. The study also evaluated the potential anti-inflammatory effect of preoperative carbon dioxide-pneumoperitoneum (CO2P).Materials and methods: Forty female Danish Landrace pigs were randomized to four groups: three intervention groups [open surgery ± prior CO2P and robot-assisted laparoscopic cystectomy (RALC)], all subjected to RC and an ileal conduit, and one control group. After euthanization, UEAs were harvested and histopathologically evaluated.Results: Five pigs were excluded from the study owing to postoperative complications. Operating room time and clamping of the right and left ureters were significantly longer in the robotic than in the open groups (p < .01). Inflammatory infiltration grade of the left ureter was significantly higher in RALC (p = .032). No statistically significant difference was observed between the open groups receiving prior CO2P or not.Conclusions: Results showed a statistically significant higher inflammatory infiltration grade of the left ureter in RALC, emphasizing the importance of using meticulous techniques when mobilizing the left ureter using the robot. It was not possible to conclude with certainty whether CO2P could constitute an anti-inflammatory agent for local inflammation.

Effect of carbon dioxide pneumoperitoneum on pharmacodynamics of rocuronium administered by closed-loop muscle relaxation injection system

Objective To investigate the effect of carbon dioxide pneumoperitoneum on pharmacodynamics of rocuronium(ROC)in gynecological laparoscopic surgery.Methods Patients of ASA Ⅰ-Ⅱscheduled for elective gynecological laparoscopic surgery(Group L,n=29)or open gynecological surgery(Group C,n=29)were given total intravenous anesthesia(TIVA)with propofol and remifentanil.All patients initially received ROC 0.6mg·kg-1 by 1.8μg·kg-1·min-1 through closed-loop muscle relaxation injection system.ROC(30μg·kg-1·min-1)was given to maintain muscle relaxation when T1 reached 15%of control.The onset time of ROC(T1down to 0%),the first time of ROC injection(T1reach 15%),recovery index of muscle relaxation(T1increase from 25% to 75%),frequency of ROC injection and injection dosage per unit time were recorded.The hemodynamic parameters including heart rate(HR),mean arterial pressure(MAP),cardiac output(CO),PaCO2,pH and depth of anesthesia(bispectral index,BIS)were also recorded before intubation(P0),after intubation(P1),5min after pneumoperitoneum(P2),30 min after pneumoperitoneum(P3),1hafter pneumoperitoneum(P4),the end of pneumoperitoneum(P5)and time of removal of intubation(P6).Results The first time of ROC injection in group L was significantly longer than that in group C([42.1±10.7]min vs[27.7±9.5]min,P0.01),and the recovery index of muscle relaxation in group L was significantly longer than that in group C([13.8±6.0]min vs[9.6±3.9]min,P0.01).The total dosage per unit time of ROC in group L was significantly less than that in group C([5.4±0.8]μg·kg-1·min-1 vs[6.3±0.5]μg·kg-1·min-1,P0.05).The frequency of ROC injection in group L was significantly less than that in group C([2.1±1.0]per hour vs[2.8 ±0.9]per hour,P0.05).Hemodynamically,CO in group L was found significantly lower than that in group C during P2-P4(P0.01).Conclusion The duration and recovery time of ROC in patients undergoing laparoscopic surgery under carbon dioxide pneumoperitoneum are prolonged,and smaller dosage is required compared to opengynecological surgery,which is likely due to the lower CO caused by carbon dioxide pneumoperitoneum.

The effect of carbon dioxide pneumoperitoneum on the healing colonic anastomosis in rats

To investigate the effects of pneumoperitoneum on colonic anastomosis healing. Colonic anastomosis was performed in 120 rats divided into four groups: Group I - pneumoperitoneum before laparotomy, Group II - pneumoperitoneum after laparorrhaphy, Group III - pneumoperitoneum before laparotomy and after laparorrhaphy, Group IV - no pneumoperitoneum (control group). Pneumoperitoneum pressure was 5 mmHg. Animals were killed on the 3rd, 7th and 14th postoperative day. Histopathological features, anastomosis breaking strength, collagen histomorphometry and hydroxyproline concentration were assessed. Breaking strength between groups: (day 3, p=0.165; day 7, p=0.219; day 14, p=0.539). Histopathology revealed that group II had, on day 7, less infiltration of mononuclear cells (p=0.006), greater infiltration of polymorphonuclear cells (p=0.001) and greater necrosis (p=0.001); and on day 14, less fibrosis. Histomorphometry revealed a decrease in collagen in groups I and III (p<0.001) on day 7 and an increase in groups I and II on day 14 (p<0.001). Hydroxyproline concentration was similar for groups on days 3 (p=0.152), 7 (p=0.913) or 14 (p=0.981). Carbon dioxide does not impair the healing of colonic anastomosis in rats.

Effect of carbon dioxide pneumoperitoneum on neuromuscular block of cisatracurium in patients undergoing laparoscopic operation

Objective To investigate the effect of carbon dioxide ( CO2 ) pneumoperitoneum on the neuromuscular block of cisatracurium in patients undergoing laparoscopic operation.Methods Sixty ASA Ⅰ or Ⅱ patients,aged 35-60 yr,with body mass index of 18-24 kg/m2,scheduled for elective hysterectomy,were randomly divided into 2 groups ( n =30 each ):pneumoperitoneum group ( group P) and control group ( group C ).Each group was further divided into 2 subgroups according to the use of the antagonist of neuromuscular block ( n =15 each):no neostigmine group ( group P0 or C0 ) and neostigmine group (group P1 or C1 ).Anesthesia was induced with fentanyl,propofol and cisatracurium and maintained with target-controlled infusion of propofol and remifentanil.Tracheal intubation was performed and the patients were mechanically ventilated.Neuromuscular function was monitored by TOF-Watch SX accelerography (Organon Co.,Organon).A train of four (TOF) stimulation of the ulnar nerve was used.When T,returned to 5％ of control height after CO2 pneumoperitoneum was established,cisatracurium 0.05 mg/kg was injected intravenously in group P.When T1 returned to 25％ of control height after the end of operation,neostigmine was injected intravenously in groups P1 andC1.The clinical duration and recovery index were recorded after CO2 pneumoperitoneum was established.Arterial blood samples were obtained immediately before induction,at 30 and 60 min of pneumoperitoneum,and at the end of operation for blood gas analysis.Results The clinical duration and recovery index were significantly longer in group P0 than in group C0,and in group P1 than in group C1 ( P ＜ 0.05).Compared with group C0,the pH value was significantly decreased and PaCO2 was significantly increased at 30 and 60 min of pneumoperitoneum,and at the end of operation in group P0 ( P ＜ 0.05).Compared with group C1,the pH value was significantly decreased and PaCO2 was significantly increased at 30 and 60 min of pneumoperitoneum,and at the end of operation in group P1 ( P ＜ 0.05).Conclusion CO2 pneumoperitoneum can strengthen the neuromuscular block induced by cisatracurium and prolong the recovery time following antangonism by neostigmine administration in patients undergoing laparoscopic operation. Key words: Atracurium; Carbon dioxide; Pneumoperitoneum; Neuromuscular blockade

Carbon dioxide pneumoperitoneum induces systemic oxidative stress: a clinical study

To investigate the effect of carbon dioxide pneumoperitoneum on systemic oxidative stress by using serum oxidative stress markers (ischemia modified albumin (IMA), malondialdehyde (MDA), total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI)) and to compare their effectiveness at clinically accepted safe intra-abdominal pressure levels (<12 mmHg). A total of 33 consecutive patients who had a unilateral ovarian cyst were enrolled for this prospective clinical study. All women underwent a laparoscopic ovarian cystectomy procedure. Venous blood was collected from patients preoperatively, 10 min after induction of anesthesia and 30 min after insufflation. Preoperative, 10(min), and 30(min) serum IMA, MDA, TOS, OSI and TAS levels were compared. The mean age was 29.3 ± 6.4 and the range of operation time was 45-80 min. The mean serum IMA levels showed a significant increase 30 min later from CO(2) insufflation (p<0.05). Significant alterations were not observed in serum MDA, TOS, OSI or TAS levels. Laparoscopic surgery causes systemic ischemia and this ischemic effect can be revealed by measuring serum ischemia modified albumin. IMA is more sensitive than MDA, TOS, OSI and TAS in early detection of systemic oxidative stress.

Does pneumoperitoneum increase or decrease the serum levels of interleukin-6?

I read with great interest the recently published article by Schmidt et al. [1] regarding the effect of carbon dioxide pneumoperitoneum. In the summary of their excellent article, they conclude that the interleukin-6 (IL-6) level is significantly higher in the pneumoperitoneum group at 24 h and on day 4. A completely contrasting result can be seen in Fig. 3 (postoperative proinflammatory IL-6 at different postoperative time points; *p 0.05), which shows significantly lower levels of something after 48 h and 4 days than in control animals. This contradiction is quickly solved as we read this article further. Figure 4A (effect of carbon dioxide pneumoperitoneum on liver regeneration as assessed by measurement of regenerating liver mass on days 2 and 4) correctly shows the postoperative proinflammatory IL-6 levels at different postoperative time points. The mixing of these figures is unfortunate.

Effect of carbon dioxide pneumoperitoneum on regional cerebral oxygen saturation during laparoscopic surgery in Trendelemburg position

Doménech, P.; Hernández-Palazón, J.; Sánchez-Ródenas, L.; Pérez-Bautista, F.; Sánchez-Amador, A.; Clavel, N. Author Information

Effect of carbon dioxide pneumoperitoneum on bacteraemia and endotoxaemia in an animal model of peritonitis

Effect of carbon dioxide pneumoperitoneum on bacteraemia and endotoxaemia in an animal model of peritonitis

Effect of carbon dioxide pneumoperitoneum on bacteraemia and endotoxaemia in an animal model of peritonitis.

Laparoscopy is increasingly used in conditions complicated by peritonitis. A theoretical concern is that carbon dioxide pneumoperitoneum may increase bacteraemia. This study examines the effect of carbon dioxide pneumoperitoneum on bacteraemia, endotoxaemia and physiological correlates of sepsis in an animal model of peritonitis. New Zealand white rabbits were assigned to three groups of six animals. Group 1 received an intraperitoneal inoculation of 10(9) colony-forming units of Escherichia coli followed by a 10-cm midline laparotomy. Group 2 received an identical bacterial inoculum followed by a 12-mmHg carbon dioxide pneumoperitoneum for 1 h. Group 3 received no bacteria but had a 12-mmHg carbon dioxide pneumoperitoneum for 1 h. Groups 1 and 2 had significantly higher levels of bacteraemia (P < 0.01) and endotoxaemia (P < 0.01) accompanied by significantly lower mean arterial pressures (P < 0.05) and higher heart rates (P < 0.05) compared with group 3. After 6 h groups 1 and 2 were significantly hypocarbic (P < 0.01), leucopenic (P < 0.01) and thrombocytopenic (P < 0.01). There was no difference between group 1 and group 2. A carbon dioxide pneumoperitoneum of 12 mmHg does not increase bacteraemia or endotoxaemia, nor does it adversely affect physiological or laboratory correlates of sepsis compared with laparotomy in this animal model of peritonitis.

Effect of Carbon Dioxide Pneumoperitoneum on Development of Atelectasis During Anesthesia, Examined by Spiral Computed Tomography

Survey of Anesthesiology: October 2005 - Volume 49 - Issue 5 - p 246-247 doi: 10.1097/01.sa.0000177143.32779.61

Effect of Carbon Dioxide Pneumoperitoneum on Development of Atelectasis during Anesthesia, Examined by Spiral Computed Tomography

Anesthesia per se results in atelectasis development in the dependent regions of the lungs. The effect of pneumoperitoneum on atelectasis formation is not known. The aim of the current study was to measure by spiral computed tomography the effect of carbon dioxide pneumoperitoneum for laparoscopic surgery on the development of atelectasis, overall lung volume, and regional tissue volumes of gas and tissue. Seven patients (American Society of Anesthesiologists physical status I), scheduled to undergo laparoscopic cholecystectomy, were observed. After induction of anesthesia, the patients were mechanically ventilated and positioned supine on the computed tomography table. Tomography of the lungs (10 mm spiral) was performed before and 10 min after induction of carbon dioxide pneumoperitoneum at an intraabdominal pressure of 11-13 mmHg. The Student t test was used for statistical analysis. A P value less than 0.05 was considered significant. Induction of pneumoperitoneum increased the mean atelectasis volume in the dependent lung regions by 66% (range, 11-170%). The overall lung volume and gas as well as tissue volume significantly decreased. Relative to the total lung volume, lung tissue volume increased, while gas volume decreased significantly. Both upper and lower lobes reacted the same way. A cranial displacement of the diaphragm between 1 and 3 cm (mean, 1.9 cm) was registered. Pneumoperitoneum at an intraabdominal pressure level of 11-13 mmHg increased the volume of atelectasis. Because lung tissue volume increased in the lung, there may have been an opening of previously closed vessels, which could explain previously seen increase in arterial oxygenation after induction of pneumoperitoneum.

Effect of carbon dioxide pneumoperitoneum and wound closure technique on port site tumor implantation in a rat model

The purpose of this study was to evaluate the effects of carbon dioxide (CO2) pneumoperitoneum and wound closure technique on port site tumor implantation. A standard quantity of rat mammary adenocarcinoma (SMT2A)was allowed to grow in a flank incision in Wistar-Furth rats (n = 90) for 14 days. Thereafter, 1-cm incisions were made in each animal in three quadrants. There were six control animals. The experimental animals were divided into a 60-min CO2 pneumoperitoneum group (n = 42) and a no pneumoperitoneum (n = 42) group. The flank tumor was lacerated transabdominally in the experimental groups. The three wound sites were randomized to closure of (a) skin; (b) skin and fascia; and (c) skin, fascia, and peritoneum. The abdominal wounds were harvested en bloc on postoperative day 7. Histologic comparison of the port sites in the pneumoperitoneum and no-pneumoperitoneum groups did not demonstrate a statistically significant difference in tumor implantation for any of the closure methods. Evaluation of the closure techniques showed no statistical difference between the pneumoperitoneum group and the no-pneumoperitoneum group in the incidence of port site tumor implantation. Within the no-pneumoperitoneum group, there was a significant increase (p = 0.03) in tumor implantation with skin closure alone vs all three layers. Additionally, when we compared all groups by closure technique, the rate of tumor implantation was found to be significantly higher (p = 0.01) for skin closure alone vs closure of all three layers. This study suggests that closure technique may influence the rate of port site tumor implantation. The use of a CO2 pneumoperitoneum did not alter the incidence of port site tumor implantation at 7 days postoperatively.

Effect of carbon dioxide pneumoperitoneum on the severity of acute pancreatitis: An experimental study in rats

In the management of mild acute biliary pancreatitis, it is generally recommended to perform laparoscopic cholecystectomy after the subsidence of the attack during the same hospital admission. The effect of laparoscopy on abdominal organs has been widely investigated but not in acute pancreatitis. This study used an animal model of mild acute pancreatitis to examine the effects of CO(2) pneumoperitoneum on acute pancreatitis in rats. Mild acute pancreatitis was induced in 30 male Sprague-Dawley rats by surgical ligation of the biliopancreatic duct. After 2 days, animals were assigned to three groups: sham operation (animals were anesthetized for 30 min without undergoing laparotomy), CO(2) pneumoperitoneum (applied for 30 min at a pressure of 12 mmHg), and laparotomy (performed for 30 min, and then the abdomen was closed). Two hours after the surgical procedures, animals were killed and levels of lactate dehydrogenase, aspartate aminotransferase, glucose, urea, hematocrit, and leukocyte count among Ranson's criteria and levels of amylase, lipase, and total bilirubin were measured to determine the severity of acute pancreatitis. Histopathologic examination of the pancreas was done, and malondialdehyde and glutathione levels of the pancreas and lung were determined. The only significant differences between the groups were in lactate dehydrogenase and aspartate aminotransferase levels, which were significantly higher in the pneumoperitoneum group compared to the sham operation group. CO(2) pneumoperitoneum for 30 min at a pressure of 12 mmHg did not affect the severity of acute pancreatitis induced by ligation of the biliopancreatic duct in rats.

Effect of carbon dioxide pneumoperitoneum on tissue blood flow in the peritoneum, rectus abdominis, and diaphragm muscles.

Changes in local blood flow may play a role in the pathogenesis of port-site metastasis. This study aimed to investigate the effect of pneumoperitoneum induced by carbon dioxide (CO2) on the blood flow in the peritoneum and abdominal wall muscle layers, which are target structures for this phenomenon. The study was performed on domestic farm swine of both genders weighing 20 to 25 kg. Intraabdominal pressures (IAP) of 0, 5, and 10 mmHg were produced by either CO2 ( n = 9) or helium (He) ( n = 6) insufflations. The colored microsphere technique was used to measure blood flow distributions in the parietal peritoneum, rectus abdominis, and diaphragm muscles. Insufflation of CO2 was associated with a threefold increase in blood flow of the parietal peritoneum at both 5 and 10 mmHg IAP ( p < 0.001 for both pressure levels). In contrast, insufflation of He caused a significant decrease in blood flow in the parietal peritoneum at both 5 and 10 mmHg ( p < 0.05). In the rectus abdominis and diaphragm muscles, blood flow remained unchanged after insufflation of CO2 at both 5 and 10 mmHg IAP. However, after insufflation of He, there was a substantial decrease in blood flow both in the rectus abdominis and diaphragm muscles at both 5 mmHg ( p < 0.01 and p < 0.05, respectively) and 10 mmHg ( p < 0.001 and p < 0.01, respectively). Despite high intraabdominal pressure, tissues surrounding the abdominal cavity, particularly the peritoneum, respond to insufflation of CO2 with increased blood flow, which may favor the growth of tumor cells.

Distribution of intrasplenically injected colon cancer cells following pneumoperitoneum in mice.

Few studies have examined tumor cell distribution following laparoscopic surgery for colorectal cancer. We examined the effect of carbon dioxide pneumoperitoneum on the distribution of intrasplenically injected colon cancer cells in mice. Mice were intrasplenically injected with 2 x 10(4) colon 26 cells labeled with 111In-oxine and were randomized to undergo pneumoperitoneum at 10 mmHg for 30 min or to receive no treatment other than anesthesia. Radioactivity of the liver, lungs, and spleen was measured 30, 60, 90, or 150 min following tumor inoculation. The dynamic changes in the hepatic radioactivity were not similar between groups. However, the values were not significantly different at any time point. The radioactivity of lungs was extremely low in both groups throughout the experimental period. Pneumoperitoneum does not appear to cause the accumulation of intraportally spreading tumor cells in the liver, but it may affect the dynamic changes of tumor cells. Also, tumor cell localization in the lungs is negligible in both pneumoperitoneum and control groups.

Effects of carbon dioxide pneumoperitoneum on hemodynamics in cirrhotic rats.

The aim of our study was to investigate the effect of carbon dioxide pneumoperitoneum on systemic and splanchnic hemodynamics in cirrhotic rats. Sprague-Dawley rats (n = 80) were used in this study. Liver cirrhosis was induced by thioacetamide administration intraperitoneally (200 mg/kg body weight, twice a week for 16 weeks). The radioactive microsphere method was used to measure systemic and regional hemodynamic parameters before, 1 h after the start, and 1 h after the release of pneumoperitoneum. Splanchnic blood flow and cardiac index were significantly depressed during pneumoperitoneum in liver cirrhosis and control groups, but no significant differences were seen between the two groups. In both groups, portal venous inflow decreased and hepatic arterial blood flow increased significantly during pneumoperitoneum. However, during pneumoperitoneum, total hepatic blood flow as a percentage of its value before pneumoperitoneum was lower in cirrhotic rats (71.0%) than in control rats (91.9%) (p <0.05, Mann-Whitney U-test). Carbon dioxide pneumoperitoneum markedly decreases total hepatic blood flow in cirrhotic rats due to the impaired hepatic arterial buffer response. Liver function should be carefully controlled in cirrhotic patients after laparoscopic surgery with pneumoperitoneum.

The effect of carbon dioxide pneumoperitoneum on free radicals

Carbon dioxide is usually preferred as the insufflating agent for laparoscopic surgery because it is readily available, noncombustible, and chemically stable. It is still questionable, however, if CO2 pneumoperitoneum has any effect on free radicals and lipid peroxidation. The purpose of this study was to investigate the possible effects of CO2 pneumoperitoneum on free radicals and lipid peroxidation in the erythrocytes of rats. Fifty male Sprague-Dawley rats were divided into five equal groups: controls, a sham-operation group, and three groups of 5, 10, or 15 mmHg pneumoperitoneum with CO2. At the end of the procedure, blood was collected and the erythrocytes were separated from the plasma. The resultant supernatant fractions of erythrocytes were assayed for superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA). SOD activities of the 5 and 10 mmHg pneumoperitoneum groups were significantly lower than those of the sham operation group. SOD activity was greater in the 15 mmHg pneumoperitoneum group than in any of the other groups, and this activity was significantly different from that seen in the 5 and 10 mmHg pneumoperitoneum groups (p < 0.05). No significant changes were observed in the CAT activities of the study groups (p > 0.05). MDA level was increased in the 5 mmHg pneumoperitoneum group; this result was statistically different from the control and 15 mmHg pneumoperitoneum groups (p < 0.05). No significant differences were found in the CAT activities for the study groups. On the other hand, the SOD activities of the 5 and 10 mmHg pneumoperitoneum groups were significantly lower than those of the sham and the 15 mmHg pneumoperitoneum group (p < 0.05 for all comparisons). These results indicate that CO2 pneumoperitoneum applied with 5-10 mmHg pressure increases the formation of free oxygen radicals by inhibiting SOD activity and that the accumulation of free radicals elevates the level of MDA, a metabolite of lipid peroxidation. The effect of CO2 pneumoperitoneum on free radicals and lipid peroxidation is pressure-dependent in rats. The mechanism underlying this pressure dependency is still under investigation.