Effect of CO2 pneumoperitoneum on the systemic and peritoneal cytokine response in a LPS-induced sepsis model

We studied the effect of carbon dioxide (CO2) pneumoperitoneum on the systemic and peritoneal cytokine response in a rat model of intraperitoneal sepsis. After intraperitoneal injection of bacterial lipopolysaccharide (LPS, 10 mg/kg), rats were divided into 3 groups (n = 49 in each group): control (abdominal puncture); CO2 pneumoperitoneum, and laparotomy. Blood and peritoneal lavage fluid (PLF) were sampled at 0, 1, 2, 3, 4, 6, and 8 h after LPS challenge. Blood cell counts, plasma endotoxin level, and the levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) in the plasma and PLF were measured. Blood cell counts did not differ between the 3 groups. Plasma endotoxin levels in the pneumoperitoneum group were significantly increased immediately after the procedure (p < 0.05). Although peak plasma TNF-alpha levels in the pneumoperitoneum group were seen immediately after the procedure, other changes in plasma cytokine levels did not differ significantly between the 3 groups. PLF TNF-alpha and IL-1beta levels in the pneumoperitoneum group were significantly lower than levels in the control and laparotomy groups soon after the procedure (p < 0.05). PLF IL-6 levels in the pneumoperitoneum group tended to be lower than those in the laparotomy group. In conclusion, CO2 pneumoperitoneum might induce different responses between systemic and peritoneal cytokines soon after the procedure in a rat model of intraperitoneal sepsis.     

Effects of laparoscopic models on anaerobic bacterial growth with bacteroides fragilis in experimentally induced peritonitis

BACKGROUND: Previous reports of recurrent intra-abdominal abcess formation after the laparoscopic treatment of perforated acute appendicitis led us to investigate the possible effects of gas insufflation on the spread of infection. We previously showed that Escherichia coli counts were significantly higher in a laparoscopy group that underwent carbon dioxide (CO2) insufflation than in control and laparotomy groups. The aim of this study is to investigate the effects of intra-abdominal CO2 and nitrous oxide (N2O) insufflation on anaerobic bacterial growth in a rat model. METHODS: A standard strain of Bacteroides fragilis (ATCC 25285) was injected intraperitoneally (1 x 10(6) cfu/mL per kilogram) in 40 Wistar rats under sterile conditions. Forty rats with induced peritonitis were randomly divided into five groups: control, laparotomy, CO2 insufflation, N2O insufflation, and one group without pneumoperitoneum. Eight hours after the intraperitoneal injection of B. fragilis, peritoneal aspirates were obtained and inoculated onto Brucella agar. At the sixteenth hour of induced peritoneal infection (corresponding to hour 8 in the laparoscopy groups) all animals underwent laparotomy; peritoneal aspirates were obtained and inoculated into Brucella agar for bacterial counts. The colonies of B. fragilis were counted manually, and the results were expressed as the mean number of colony-forming units per milliliter. RESULTS: No significant differences in microorganism counts were noted between the study groups before the procedure (p>.05 for all comparisons). We observed a significant increase in the number of bacteria (mean +/- SD) in the CO2 insufflation group between hour 8 and hour 16 of peritoneal contamination. CONCLUSION: The results suggest that CO2 insufflation may promote the growth of intra-abdominal anaerobic bacteria. Such bacterial growth may lead to intra-abdominal abcess formation or cause localized peritonitis to develop into generalized peritonitis. We suggest that laparoscopy without pneumoperitoneum may be preferred in patients with peritonitis.     

Is helium insufflation superior to carbon dioxide insufflation in bacteremia and bacterial translocation with peritonitis?

PURPOSE: To evaluate the effects of CO2 or helium insufflation on bacteremia and bacterial translocation in rats with peritonitis. MATERIALS and METHODS: Forty male Wistar-Albino rats were divided into four groups, each containing 10 rats. The rats in the first group were injected only with E. coli into their peritoneal cavities with no further manipulation. The second group, following E. coli injection, underwent midline laparotomy without manipulation of the viscera for 1 hour. After the injection of E. coli in the third and fourth groups, CO2 and helium pneumoperitoneum, respectively, were maintained for 1 hour under 14 mm Hg pressure. At the end of the sixth hour, tissue samples were taken from the liver, spleen, lung, and mesenteric lymph nodes in order to evaluate bacterial translocation. During the study, blood samples were taken from each rat at 0, 1, 2, 4, and 6 hours to demonstrate bacteremia. RESULTS: There was a significant increase in bacteremia in the CO2 pneumoperitoneum group compared with the laparotomy-only and helium groups at 1 and 2 hours. Although all the blood samples at the fourth hour were positive for E. coli in every rat of all groups, helium was associated with a lower incidence of bacteremia at the sixth hour compared with other groups (P < 0.05). The CO2 pneumoperitoneum caused bacterial translocation to all organs from which tissue samples were taken. Although there was an insignificant decrease in translocation to the liver, spleen, and lung with helium compared with CO2 insufflation, helium did not increase bacterial translocation to the spleen compared with laparotomy alone, as did CO2 (P < 0.05). CONCLUSION: Helium might be an alternative to CO2 insufflation in patients with peritonitis if these results are confirmed by further experimental and clinical trials.     

Effect of abdominal insufflation on bacterial growth in experimental peritonitis

BACKGROUND: Perforated appendicitis can be treated laparoscopically, but this approach is associated with a higher rate of intra-abdominal abscess. Pneumoperitoneum impairs the clearance of bacteria from the peritoneal cavity in experimental models of peritonitis. The aim of this study was to investigate the effects of intra-abdominal gas insufflation on bacterial growth in a rat model. MATERIALS AND METHODS: The effects of intraperitoneal insufflation with different gases and a gasless model on bacterial proliferation in a setting of Escherichia coli-induced experimental peritonitis were studied in a rat model. Saline (0.25 mL) was given intraperitoneally to six Wistar male rats as the sham group. Escherichia coli (1.5 x 10(9) cfu/mL per kilogram) was injected intraperitoneally into to 24 rats. Microorganism counts were taken after 8 hours, and rats were divided into three groups: group 1, CO2 insufflation; group 2, N2O insufflation; and group 3, no insufflation. Microorganism counts were repeated 8 hours after the procedure (at 16 hours postinjection). RESULTS: The difference in microorganism counts between 8 and 16 hours were significant in the CO2 and N2O insufflation groups (P < 0.05) but not in the group without pneumoperitoneum. CONCLUSIONS: Abdominal insufflation may promote intra-abdominal bacterial growth or decrease intra-abdominal bacterial clearance.     

Effect of bile on growth, peritoneal absorption, and blood clearance of Escherichia coli in E coli peritonitis

The effect of intraperitoneal bile on growth, peritoneal absorption, and clearance of Escherichia coli was determined in E coli peritonitis in the rat. In E coli peritonitis, intraperitoneal bacterial counts gradually decreased, whereas they increased (after 2 hours) with subsequent development of bacteremia in E coli plus bile peritonitis. After an intraperitoneal injection of labeled bacteria, blood radioactivity was only initially lower in E coli plus bile peritonitis compared with E coli peritonitis. Clearance from blood was lower in E coli plus bile peritonitis than in E coli peritonitis. Organ localization was similar in E coli peritonitis and E coli plus bile peritonitis with decreased splenic, increased pulmonary, and unchanged hepatic uptakes compared with controls. Impaired peritoneal absorption of bacteria, together with impaired local host defense, is likely to enhance the noxious effect of bile in E coli peritonitis.     

Lavage by laparoscopy fares better than lavage by laparotomy

Background: Although carbon dioxide (CO2) pneumoperitoneum is proposed increasingly for treatment of secondary peritonitis, associated deleterious effects have been reported in experimental models, with the hypothesis that increased intraperitoneal pressure might facilitate bacterial translocation. The purpose of this study was to compare the outcome (and qualitative microbiologic analysis) from peritonitis in rats after lavage by laparoscopy with the outcome after lavage by laparotomy. Methods: After determination of the standard innoculum for this study in 30 animals, 120 male Wistar rats received 1 ml of Escherichi coli 106 colony-forming unit (CFU), Bacteroides fragilis 107 CFU, Enterococcus faecalis 107 CFU in a sterile rat feces-barium sulfate suspension adjuvant, were anesthetized with intramuscular ketamine, and then underwent peritoneal lavage by either laparotomy (n = 60) or laparoscopy (n = 60). The duration of peritonitis defined two groups: group A: duration less than 3 h (n = 20) and group B: duration 3 h or more (n = 40). Both groups underwent successive lavage with 10-ml aliquots (total, 50 ml) of 0.9% saline solution at 37°C. Five 2-ml samples of liquid lavage were drawn for culture and microbiologic analysis. Blood (0.2 ml) and peritoneal liquid lavage samples were incubated 48 h at 37°C and cultured. Results: All the animals survived. Mean duration of peritoneal lavage was 13.2 min (range, 6-25 min) for laparoscopy and 9.7 min (range, 6-15 min) and for laparotomy. The difference was not statistically significant. The mean duration of operation was significantly longer with laparoscopy than with laparotomy: 44.5 min (range, 35-62 min) and 25 min (range, 16-40 min), respectively (p = 0.0001). The collected lavage volumes were not statistically different: 48.5 ml (range, 40-54 ml) and 46.7 ml (range, 37-56 ml), respectively. No statistically significant differences were found between the laparoscopy and laparotomy groups in terms of E. coli bacteremia, irrespective of peritonitis duration. The rates of positive blood culture for B. fragilis and E. faecalis were signficantly lower after laparoscopy than after laparotomy, both in the overall group (p = 0.025 and p = 0.045, respectively) and when duration of peritonitis exceeded 3 h (p = 0.001 and p = 0.044, respectively). Conclusions: In this animal model of secondary peritonitis, lavage by laparoscopy was associated with less bacteremia for B. fragilis and E. faecalis than peritoneal lavage by laparotomy.     

Bile increases lipopolysaccharide release in experimental E. coli peritonitis.

Previous studies in rats showed increased mortality when bile was added to intraperitoneally injected Escherichia coli. In the present study bacterial counts and levels of lipo-polysaccharide (LPS) were determined in the peritoneal cavity and in blood 0.5, 1, 4 and 10 hours after induction of peritonitis with E. coli alone or together with bile. LPS was measured with gas chromatographic analysis of beta-hydroxymyristic acid, a characteristic component of E. coli-LPS. Bacterial counts and LPS levels in peritoneal fluid and blood rose higher in E. coli + bile peritonitis than in E. coli peritonitis. The intergroup difference in LPS levels was evident at 0.5 and 1 hour, whereas the bacterial counts began to differ at 2 hours. Presence of intraperitoneal bile in E. coli peritonitis thus produced rapid rise in LPS levels that could not be caused by bacterial numbers alone. This early load of LPS may help to explain the noxious effect of bile in E. coli peritonitis.     

The adjuvant effect of peritoneal fluid in experimental peritonitis. Mechanism and clinical implications

At laparotomy, many surgeons routinely instill crystalloid solutions into the peritoneal cavity, presumably to dilute out necrotic debris, bacteria, and adjuvant substances which foster bacterial growth. We examined the effect on mortality, bacterial growth, clearance, and phagocytosis of various volumes of saline instilled into the peritoneal cavity of rats during Escherichia coli peritonitis. Minimal intraperitoneal bacterial growth was seen after the introduction of a nonlethal inoculum of viable E. coli in 1 ml of saline, while administration of an identical inoculum in 30 ml of saline intraperitoneally (i.p.) led to increased 48-hour mortality (p less than 0.01), and associated rapid bacterial proliferation (p less than 0.01). Clearance of nonviable radiolabelled E. coli from the peritoneal cavity was delayed, bacterial association with host peritoneal leukocytes was decreased, and blood uptake of radiolabelled bacteria was diminished in animals receiving 30 ml of saline i.p., compared to controls which received the identical inoculum in 1 ml of saline i.p. The clinical relevance of these studies is manifold: (1) they provide a possible explanation why patients with ascites due to cirrhosis or the nephrotic syndrome, or those patients undergoing peritoneal dialysis are more susceptible to primary and secondary bacterial peritonitis, possibly on the basis of impaired peritoneal clearance or diminished phagocytosis and, (2) although irrigation of the peritoneal cavity with crystalloid solution would seem prudent during laparotomy, these solutions must be removed prior to closure to prevent interference with normal peritoneal host defense mechanisms.     

Does laparoscopy increase bacteremia and endotoxemia in a peritonitis model?

Background: Laparoscopy is increasingly used in patients with intraabdominal bacterial infection although pneumoperitoneum may increase bacteremia by elevated intraabdominal pressure. Methods: The influence of laparotomy and laparoscopy on bacteremia, endotoxemia, and postoperative abscess formation was investigated in a rat model. Rats received intraperitoneally a standardized fecal inoculum and underwent laparotomy (n= 20), or laparoscopy (n= 20), or no further manipulation in the control group (n= 20). Results: Bacteremia and endotoxemia were higher after laparotomy and laparoscopy compared to the control group (p= 0.01) 1 h after intervention. One hour after intervention, aerobic and anaerobic bacterial species were detected in the laparotomy group while only anaerobic bacteria were found in the other two groups. Although bacteremia and endotoxemia did not differ among the three groups after 1 week, the mean number of intraperitoneal abscesses was significantly higher (p < 0.05) after laparotomy (n= 10) compared with laparoscopy (n= 6) and control group (n= 5). Conclusion: Laparoscopy does not increase bacteremia and intraperitoneal abscess formation compared to laparotomy in an animal model of peritonitis. Received: 28 May 1996/Accepted: 25 July 1996     

Impact of surgical peritoneal environment on postoperative tumor growth and dissemination in a preimplanted tumor model

Background  We recently demonstrated that CO₂ pneumoperitoneum at low intraperitoneal pressure (IPP) had few if any short-term effects on peritoneal dissemination when an ovarian cancer cell line was inoculated just prior to surgery. The objective of the present study was to evaluate the impact of surgical peritoneal environment on postoperative tumor growth and dissemination over time when tumors were present before surgery. Methods  On day-7, C57BJ6 mice received an intraperitoneal inoculation of a mouse ovarian cancer cell line (ID8). On day 0, mice were randomized into four groups: anesthesia alone, CO₂ pneumoperitoneum at a low (2 mmHg) or high (8 mmHg) IPP, or laparotomy. Groups were further subdivided into four groups of eight animals each and a laparotomy was performed to evaluate dissemination on postoperative day (POD) 1, 2, 7 or 14. Results  Peritoneal dissemination score was significantly higher in the laparotomy group compared with in the remaining three groups on PODs 2 and 7. We detected no significant differences in the peritoneal dissemination scores among the low-IPP, high-IPP, and anesthesia groups on PODs 2 and 7. However, there were no significant differences in the peritoneal dissemination score among the three surgical groups on POD 14. Histopathological examination demonstrated that the incidence of invasion of cancer cells into the muscle layers was significantly higher in the laparotomy group than in the low-IPP and anesthesia groups on POD 14. There were no significant differences in tumor growth among the four groups. Conclusions  The present findings suggest that CO₂ pneumoperitoneum at either high or low IPP has few if any short-term effects on peritoneal dissemination when tumors are well established before surgery. This study was supported in part by la Ligue Régionale de Lutte contre le Cancer (Auvergne region, France) and Karl Storz Endoscopy GmbH (Tuttlingen, Germany).     

Influence of omentectomy on peritoneal defense mechanisms in an experimental model of intra-abdominal infection

BACKGROUND/AIM: The omentum has an important role as part of peritoneal defense mechanisms. The aim of this study is to show the bactericidal activity of peritoneal fluid and the role of the omentum as a peritoneal defense mechanism in experimental animals with intra-abdominal infections. METHODS: 40 male Spraque-Dawley rats weighing between 250 and 300 g were used in this study. The rats were randomly divided into four groups consisting of 10 animals. The operative procedures were done under sterile conditions. In group I sham laparotomy was done. In group II, the distal part of the cecum was ligated, and cecum perforation was performed. In group III, total omentectomy was performed after cecal ligation and perforation. In group IV only omentectomy was performed. Baseline and 2- and 4-hour peritoneal fluid samples were taken using a Pasteur pipette during laparotomy under anesthesia. Total peritoneal cells counts, bactericidal activity of peritoneal fluid, and types of phagocytic cells in the peritoneal fluid were assessed. RESULTS: As compared with baseline values, the total peritoneal cell counts were increased at the 2nd and 4th h in all groups (p < 0.05). A significant increase was observed after 4 h as compared with 2 h in sham laparotomy, cecal ligation+perforation+omentectomy, and omentectomy groups (p < 0.05). A significant increase in the cell counts after 2 h was found in the other groups when compared to the sham laparotomy group (p = 0.0001). After 4 h, there was a significant difference between the groups, but especially prominent in the cecum ligation+perforation+omentectomy group (p = 0.0001). Proliferating colony counts of Escherichia coli and Pseudomonas Aeruginosa decreased after 2 h, and there was no proliferation in the subsequent cultures. It was observed that the macrophage counts significantly increased after 2 and 4 h as compared with baseline in intragroup assessments (p = 0.0001). In the intergroup assessment, an increase was observed in the macrophage counts at baseline and after 2 and 4 h, and this was significant in the cecal ligation+perforation+omentectomy group (p = 0.0001). In the omentectomy group, a significant decrease was observed in the macrophage counts between the 2nd and 4th h (p = 0.0001). CONCLUSION: Removal of the omentum in the presence of intra-abdominal infections causes the peripherally derived macrophages to take over the defensive role of macrophages of peritoneal origin as a compensatory mechanism, thus the peritoneal bactericidal activity against E. COLI, the major pathogen in intra-abdominal infections, does not change after omentectomy.     

Laparoscopic pneumoperitoneum in acute peritonitis does not increase bacteremia or aggravate metabolic or hemodynamic disturbances

The use of laparoscopy in generalized peritonitis has become increasingly frequent in recent years. However, CO2 pneumoperitoneum in association with increased intraperitoneal pressure may have deleterious effects in patients with hemodynamic or metabolic disturbances caused by bacterial peritonitis. The purpose of this study was to investigate the effect of CO2 pneumoperitoneum on bacteremia, mean arterial pressure, and blood gas disturbances in an animal model of bacterial peritonitis. Dogs were anesthetized, orally intubated, and subjected to experimental peritonitis by intraperitoneal inoculation of a suspension containing Escherichia coli and sterile dog feces. The animals were randomly assigned to two groups: control animals were maintained under anesthesia, and the insufflated animals were subjected to intraperitoneal CO2 insufflation. Bacterial peritonitis provoked the appearance of bacteremia and a significant decrease in mean arterial pressure, pH, bicarbonate, and base deficit. The induction of bacterial peritonitis did not significantly influence pH in the control group and partial pressure of arterial CO2 in either group. Thirty minutes of CO2 pneumoperitoneum did not influence the effect of bacterial peritonitis on the analyzed variables. These results suggest that laparoscopic CO2 pneumoperitoneum does not aggravate bacteremia or metabolic and hemodynamic disturbances induced by bacterial peritonitis.     

右美托咪定两种给药方法在急性腹膜炎小鼠局部组织的抗炎镇痛作用中的比较

目的通过观察比较右美托咪定静脉注射和腹腔注射两种给药方法在急性腹膜炎模型小鼠炎性内脏痛的镇痛及抗炎作用。方法 SPF级健康成年雄性小鼠60只,体重24~28 g,采用随机数字表法分为五组,每组12只:空白对照组(CK组)、急性腹膜炎模型组(VP组)、右美托咪定静脉注射组(DEX-V组)、右美托咪定腹腔注射组(DEX-P组)、右美托咪定+甲基牛扁碱组(DEX-M组)。VP组、DEX-V组、DEX-P组DEX-M组腹腔注射0.9%乙酸溶液0.1 ml/10 g建立急性腹膜炎模型,CK组腹腔注射等容量生理盐水。于造模前15 min,VP组、DEX-P组分别经腹腔注射生理盐水、右美托咪定10μg/kg,DEX-V组经尾静脉注射右美托咪定10μg/kg,DEX-M组经腹腔注射右美托咪定10μg/kg和α7nACh受体特异性拮抗剂甲基牛扁碱2.4μg/g。观察并记录小鼠急性腹膜炎模型建立后2 h内的镇静情况、扭体反应和内脏痛指数(VPI评分);建模6 h后取材并采用ELISA法检测小鼠血清和腹膜组织匀浆中IL-6、TNF-α的浓度;取小鼠腹腔注射部位壁层腹膜组织,在光镜下观察其水肿程度和中性粒细胞浸润情况。结果与CK组比较,VP组、DEX-V组、DEX-P组和DEX-M组均出现扭体反应,给药后15、30、45、60、75、90、105、120 min时VPI评分明显升高(P<0.05),血清和腹膜组织匀浆的IL-6和TNF-α浓度均明显升高(P<0.05),腹膜组织出现不同程度水肿及中性粒细胞浸润;与VP组比较,DEX-V组和DEX-P组镇静效果较好,给药后30、45、60、75 min时VPI评分明显降低(P<0.05),血清和腹膜组织匀浆的IL-6和TNF-α浓度均明显降低(P<0.05),腹膜组织水肿减轻、中性粒细胞浸润减少;与DEX-P组比较,DEX-V组腹膜组织匀浆中的IL-6和TNF-α浓度明显升高(P<0.05);DEX-M组镇静情况、给药后45、60、75、90 min时VPI评分、血清和腹膜组织匀浆的IL-6和TNF-α浓度均明显升高(P<0.05),局部腹膜组织水肿明显加重,中性粒细胞浸润增多。结论右美托咪定局部腹腔注射可以有效降低急性腹膜炎小鼠的内脏痛指数,对局部腹膜组织有抗炎作用且效果优于静脉注射,其抗炎机制可能部分与激活a7nACh受体引导的胆碱能抗炎通路有关。     

Effect of intraperitoneal administration of oxygen on the course of experimentally induced peritonitis

Over the first 3 days of experimentally induced peritonitis, 40 rabbits were given oxygen intraperitoneally (IP) up to a pressure of 3 to 5 mm Hg in the peritoneal cavity at 12-hour intervals. Compared with a control group, significant differences were recorded in the mortality rate within the studied 7-day period of peritonitis (p less than 0.05). In 29 rabbits with intraperitoneal administration of oxygen, the size of the area that formed the inner wall of the abscess cavity was significantly smaller (p less than 0.01) on day 7 of peritonitis than in the control group. The number of samples obtained from the abscesses positive for Clostridium perfringens (p less than 0.05) and for Staphylococcus aureus (p less than 0.001) was significantly lower in rabbits that had received intraperitoneal oxygen than in the control group. The number of samples from the abscesses positive for Escherichia coli and Streptococcus faecalis was significantly lower in the control group than in the group with intraperitoneal administration of oxygen (p less than 0.05). These results indicate that intraperitoneal administration of oxygen has an effect on the mortality rate associated with peritonitis, the size of the intraperitoneal abscess, and the bacterial composition of these abscesses.     

The effect of the pneumoperitoneum on the peritoneal defense mechanisms in diabetic rats

To investigate the effects of pneumoperitoneum on the peritoneal defense mechanism induced by streptozocin infusion during laparoscopic surgery in diabetic rats and to show the importance of regulation of diabetes for peritoneal defense mechanisms. One hundred twenty-six Sprague-Dawley male rats were allocated into six groups each consisting of 21 rats: group 1, nondiabetic sham laparotomy (control); group 2, nondiabetic pneumoperitoneum (control); group 3, uncontrolled diabetes plus sham laparotomy; group 4, controlled diabetes plus sham laparotomy; group 5, uncontrolled diabetes plus pneumoperitoneum; and group 6, controlled diabetes plus pneumoperitoneum. Diabetes was constituted by intraperitoneal infusion of one dose of 60 mg/kg streptozotocin, and diabetes was regulated (in groups 4 and 6) by subcutaneous injection of 10 IU/kg insulin in the morning and evening after the blood glucose measurements since the fourth day. Peritoneal fluid samples were taken at the zero, second, and sixth hours after sham laparotomy for groups 1, 3, and 4 and after pneumoperitoneum for groups 2, 5, and 6 on the seventh day. Total peritoneal cell count, antibacterial activity of the peritoneal fluid, and types of phagocytic cells in the peritoneal fluid were assessed. Peritoneal cell count was found to be lower in uncontrolled diabetes due to high blood glucose levels (>200 mg/dL), which led to slow migration of phagocytic cells into the peritoneum. Pneumoperitoneum had augmented the effect on phagocytic cell migration to the peritoneum compared with the sham laparotomy in controlled diabetic rats. Uncontrolled and controlled diabetes have adverse effects on peritoneal defense mechanism killing functions by interfering with the antimicrobial activity of peritoneal fluid.     

Inflammatory response and bacterial dissemination afterlaparotomy and abdominal CO2 insufflation in a murine model of peritonitis

Background The immunologic repercussions due to cavity insufflation are the focus of great discussion. The aim of this study was to compare the inflammatory response and bacterial dissemination after laparotomy and abdominal CO₂ insufflation in a murine model of peritonitis. Methods Swiss mice were inoculated intraperitoneally with 0.5 ml of a solution containing 1 × 10⁸ colony-forming units (CFU)/ml of Escherichia coli and were divided into three groups as follow: control (anesthesia for 30 min), laparotomy (2.5-cm midline incision for 30 min), and CO₂ pneumoperitoneum (CO₂ cavity insufflation for 30 min). The number of leukocytes, CFU/ml counting, and the levels of interleukin (IL)-6, tumor necrosis factor-α (TNF-α), and IL-10 were evaluated in blood, peritoneal, and pleural fluid samples obtained at 90 min and 18 h after the procedures. Results The laparotomy group showed a greater bacterial dissemination to the blood, peritoneum, and pleural cavity and also greater neutrophil migration to the peritoneal cavity compared to the CO₂ insufflated and control groups. The 24-h mortality was also significantly higher in the laparotomy group. The IL-6 levels showed a precocious rise in all groups submitted to bacterial inoculation at the 90-min time point. At the 18-h time point, IL-6 levels in the peritoneum were significantly higher in the laparotomy group than in the control or CO₂ insufflated groups. At the same time, TNF-α levels were higher in the laparotomy and CO₂ insufflated groups than in controls; IL-10 levels showed no differences among the groups. Conclusions Our results suggest that cavity insufflation with CO₂ is a more effective method of access, inducing less bacterial dissemination and also a less intense inflammatory response. Cavity insufflation with CO₂ may present a good option for the surgical treatment of patients with bacterial peritonitis.     

Chemotactic substances in the treatment of experimental intraperitoneal infections.

Since peritonitis remains a serious clinical problem, we have evaluated the prophylactic efficacy of intraperitoneally administered chemotactic substances in murine intraperitoneal infections. The injection of 10 ml of 3% thioglycollate increased the peritoneal white blood cell count of rats from 1.3 +/- 0.1 X 10(6) (mean +/- SEM) to 1.1 +/- 0.1 X 10(7) (mean +/- SEM) cells/ml. This increase in the number of intraperitoneal phagocytes resulted in reduction in mortality caused by an inoculum consisting of E. coli and hemoglobin from 68% in the control group to 29% in the thioglycollate pretreated group (p less than or equal to 0.02). Intraperitoneal injection of N-formyl-methionyl-phenylalanine (FMP), a chemotactically active oligopeptide, increased the intraperitoneal granulocyte count from virtually 0 to 1 X 1.9 +/- 0.53 X 10(4) (mean +/- SEM) cells/ml after 90 minutes. The rats pretreated in such a manner showed a mortality of 51% after an intraperitoneal challenge with an E. coli/hemoglobin inoculum as compared to a mortality of 72% in control animals (p less than or equal to 0.025). Thus, chemotactic substances can effectively increase the number of phagocytes and concurrently induce resistance to an intraperitoneal bacterial challenge.     

Effect of carbon dioxide pneumoperitoneum on bacteremia and severity of peritonitis in an experimental model

Background: Laparoscopy is increasingly used in conditions complicated by peritonitis. A theoretical concern is that carbon dioxide pneumoperitoneum may increase bacteremia. Method: In 60 rats peritonitis was induced by cecostomy. Animals were randomly allocated to pneumoperitoneum (PP) and control groups. Blood cultures and intraabdominal swabs were assessed. A peritonitis severity score (PSS) was computed based on histology from peritoneal biopsy. Results: One hour after cecostomy neither in abdominal swabs nor in blood samples bacteria were reproduced in PP and control groups. Three hours after cecostomy the frequency of positive blood cultures was 80% and 20% in PP and control groups, respectively (p < 0.0001). Six hours after cecostomy the frequency of positive blood cultures was 100% in each group (p > 0.05). One hour after cecostomy the mean peritoneal severity score was significantly higher in the PP group than in the control group, but there was not any significant difference between groups 3 and 6 h after cecostomy. The mean peritoneal severity scores were found to be significantly increased with time when the PP groups compared with each other. Conclusion: In rats, pneumoperitoneum can't cause a more severe peritonitis but it does induce an increase in the rate of bacteremia within the early 6-h period of peritonitis. Received: 14 April 1997/Received: 18 September 1997