气腹影响肝脏吲哚青绿排泄的实验研究

目的 腹腔镜手术中气腹对机体生理功能的一些影响是已知的。本研究以吲哚青绿（ICG）药代动力学参数作为肝脏血流指数,观察气腹时的变化情况。方法 雄性Wistar大鼠18只,随机分面三组：麻醉组、开腹组、气腹组。气腹压力为8mmHg,ICG（1mg/kg0股静脉给药,进行ICG15min排泄试验。结果 分别测得各组血清ICG含量,开腹组ICG水平虽高于麻醉组,但无统计学差异（P＞0.05）。而所腹组ICG水平显著高于麻醉组及开腹组（P＜0.05）。结论 所腹使ICG排泄降低的结果,证实了腹腔镜手术中气腹压力可减少肝脏血流量。     

Hepatic and portal vein blood flow during carbon dioxide pneumoperitoneum for laparoscopic hepatectomy

Background: Laparoscopy under carbon dioxide (CO₂) pneumoperitoneum has many advantages. However, the risks of CO₂ pneumoperitoneum during laparoscopic hepatectomy (LH) have not been defined. Methods: The hemodynamics of the hepatic vein were examined during CO₂ pneumoperitoneum both pre- and posthepatectomy in eight pigs. Portal blood flow was measured with Doppler ultrasound during laparoscopic cholecystectomy in 10 human patients. Results: Experimentally, elevated intraabdominal pressure (IAP) with CO₂ insufflation produced significant increases in CO₂ partial pressure and echogenicity of the hepatic vein in the posthepatectomy group. Clinically, elevated IAP caused significant narrowing of the portal vein and significant decreases in portal blood velocity. The mean portal flow was significantly decreased with elevation of IAP >10 mmHg. Conclusions: LH with CO₂ pneumoperitoneum may lead to embolism caused by CO₂ bubbling through the hepatic vein. Elevated IAP may cause a decrease in hepatic blood flow and induce severe liver damage, especially in patients with poor liver function. Gasless laparoscopy using abdominal wall lifting should be employed in LH to avoid the risks of CO₂ embolism and liver damage. Received: 28 March 1997/Accepted: 12 September 1997     

The effect of carbon dioxide pneumoperitoneum on free radicals

Background: 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. Methods: 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). Results: 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). Conclusions: 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. Received: 16 December 1999/Accepted: 14 February 2000/Online publication: 10 May 2000     

Alterations in hemodynamics and left ventricular contractility during carbon dioxide pneumoperitoneum

Background: Carbon dioxide (CO₂) pneumoperitoneum has been shown to adversely affect hemodynamics in patients. This study specifically examines the potential contribution of altered left ventricular contractility (LVC) to hemodynamic changes observed during CO₂ pneumoperitoneum. Methods: In a canine model, LV volumes, LV pressure, and intrathoracic and central venous pressures were recorded both at basal intra-abdominal pressure (IAP) and after CO₂ insufflation to produce IAPs of 5–25 mmHg. Results: At IAPs greater than 15 mmHg, cardiac output and LV end-diastolic volume decreased. Mean arterial pressure and heart rate were unchanged. LVC, quantified using the linear Frank-Starling relationship, was not affected by increases in IAP. Conclusions: This study is the first to quantify LVC during CO₂ pneumoperitoneum and demonstrates no changes in contractility over IAPs from 5 to 25 mmHg. In the dog model, any hemodynamic alterations induced by CO₂ pneumoperitoneum are secondary to altered LV preload and not alterations in contractility or LV afterload. Received: 8 March 1996/Accepted: 23 April 1996     

Effects of laparotomy vs pneumoperitoneum on the hepatic catabolic stress response in ambulatory and stationary settings in pigs

Background: We recently demonstrated that laparoscopic cholecystectomy is followed by a much smaller hepatic catabolic stress response than conventional cholecystectomy. It is not known what is responsible for this difference. Methods: Thirty pigs were randomly allocated to the following five treatment groups: (1) laparotomy, (2) pneumoperitoneum, (3) pneumoperitoneum with insertion of four trocars, (4) laparotomy, (5) pneumoperitoneum. Groups 1–3 were operated on in an ambulatory setting, whereas groups 4 and 5 were operated on in a stationary setting. Urea synthesis, as quantified by functional hepatic nitrogen clearance, and the response of stress hormones and cytokines were assessed. Results: Laparotomy increased the functional hepatic nitrogen clearance by 195% (p < 0.001); pneumoperitoneum and trocars increased it by 145% (p < 0.001); and pneumoperitoneum alone increased it by 113% (p < 0.001). The difference between laparotomy and both pneumoperitoneum groups was significant. If the stress factor of ambulatory surgery was eliminated, the increase in functional hepatic nitrogen clearance was reduced to 87% (p < 0.01) after laparotomy and 38% (NS) for animals subject to pneumoperitoneum. There were significant differences in concentrations of stress hormones, tumor necrosis factor α, and interleukin 8 among groups intra- and postoperatively. Conclusions: The magnitude of the postoperative hepatic stress response after laparotomy compared to pneumoperitoneum with and without insertion of trocars seems to be caused by the greater trauma to the abdominal wall. Furthermore, an ambulatory setting seems to be an important postoperative stress factor in itself. Received: 28 April 1998/Accepted: 18 August 1998     

Intraperitoneal tumor growth is influenced by pressure of carbon dioxide pneumoperitoneum

Background: Several studies have indicated that the carbon dioxide (CO₂) pneumoperitoneum during laparoscopy plays a role in the pathogenesis of port-site metastases. An experimental animal study was performed to investigate the impact of various pneumoperitoneum pressures on peritoneal tumor growth. Methods: In this study, 36 male WAG rats were randomized into three groups; two groups with different pneumoperitoneum pressures (16 mmHg and 4 mmHg) and one group of gasless controls. After a pneumoperitoneum of 0.5 × 10⁶ ml was established, 531 tumor cells were injected intra-abdominally and the pneumoperitoneum was maintained for 60 min. Peritoneal tumor growth was assessed on day 11 at autopsy. Results: Peritoneal tumor growth in the 16-mmHg group was significantly greater than in the 4-mmHg group (p= 0.039) and the gasless group (p= 0.004). Conclusions: High-pressure CO₂ pneumoperitoneum stimulates intra-abdominal tumor growth. The use of low insufflation pressures in laparoscopic cancer surgery should be considered. Received: 1 December 1998/Accepted: 10 July 1999/Online publication: 9 August 2000     

Influence of nitrous oxide anesthesia on venous gas embolism with carbon dioxide and helium during pneumoperitoneum

Background: Gas embolism is a potential hazard during laparoscopic procedures. The aim of this study was to evaluate the effects of nitrous oxide (N₂O) inhalation in the case of gas embolism with carbon dioxide (CO₂) and helium during pneumoperitoneum. Methods: For this study, 20 anesthetized pigs were ventilated with N₂O (67% inspired) in O₂ (n= 10) or with halothane (0.7–1.5 inspired) in O₂ (n= 10). In each group, CO₂ (n= 5) or helium (n= 5) pneumoperitoneum was established and gas embolism induced at different rates (CO₂ at 0.5, 1, or 2 ml/kg/min; helium at 0.025, 0.05, or 0.1 ml/kg/min) through the left femoral vein a maximum of 10 min while all hemodynamic parameters were continuously monitored. Results: In the CO₂ group without N₂O, all the animals tolerated rates of 0.5 and 1 ml/kg/min over the 10 min, whereas only 3 of 4 animals in the CO₂ group with N₂O tolerated a rate of 0.5 ml/kg/min, and 2 of 4 animals a rate of 1 ml/kg/min. In the helium group without N₂O, all the animals tolerated gas embolism at all rates, whereas in the helium group with N₂O, 4 of 5 animals needed to be resuscitated at a rate of 0.1 ml/kg/min and one death occurred. Conclusions: Inhalation of N₂O worsens the negative cardiovascular effects of venous CO₂ or helium gas emboli and increases the risk of emboli-induced death when CO₂ or helium are used to establish pneumoperitoneum. The volume of venous venous helium gas emboli causing such effects is substantially smaller than that for venous CO₂ gas emboli. Received: 20 September 1999/Accepted: 1 October 2000/Online publication: 4 August 2000     

Changes in splanchnic blood flow and cardiovascular effects following peritoneal insufflation of carbon dioxide

Summary Laparoscopic surgery has rapidly become a popular and widely used technique. Although this procedure has been shown to be generally safe, cardiovascular derangement related to carbon dioxide pneumoperitoneum has been reported. There are few data available on the relationship between systemic and regional hemodynamics in cases of pneumoperitoneum. Changes in splanchnic blood flow and cardiovascular effects following a moderate increase of intraabdominal pressure (IAP) to 16 mmHg during a 3-h period were analyzed in six anesthetized dogs. After insufflation, cardiac output and blood flow in the superior mesenteric artery and portal vein decreased progressively and returned to the preinsufflation values following deflation. Hepatic arterial blood flow did not change significantly, perhaps due to compensatory mechanisms for maintenance of hepatic blood flow. Mechanical compression of the splanchnic capillary beds due to the elevated IAP may possibly reflect the increase in systemic vascular resistance causing the decrease in cardiac output. To prevent this impairment, intermittent decompression of gas during surgical laparoscopy is recommended.     

The influence of different insufflation pressures during carbon dioxide pneumoperitoneum on the development of pulmonary metastasis in a mouse model

Background: The effects of different insufflation pressures on the development of pulmonary metastasis was investigated in a mouse laparoscopy model. Methods: BALB/C mice intravenously inoculated with colon 26 cells were randomized to one of five treatment groups (10 mice per group): pneumoperitoneum at different pressures of 5, 10 or 15 mmHg; full laparotomy for 60 min; or anesthesia control. Cancer nodules on the lung surface 19 days postoperatively were compared between groups. Results: (a) As compared with the control group, pneumoperitoneum at 10 and 15 mmHg and laparotomy enhanced the growth of pulmonary metastases (p < 0.01). (b) The growth of metastases also was greater in laparotomy group mice than in mice undergoing pneumoperitoneum at 5 and 10 mmHg (p < 0.05). Conclusions: These results suggest that the effects of different insufflation pressures on the growth of pulmonary metastases are not identical, and that pneumoperitoneum with high pressure may promote pulmonary metastases similar to those with laparotomy. Received: 4 November 1999/Accepted: 20 December 1999/Online publication: 25 April 2000     

Characteristic alterations of the peritoneum after carbon dioxide pneumoperitoneum

Objective: Any route of entry into the abdomen contributes to alterations of the intraperitoneal organs with different clinical consequences. Characteristic alterations of the peritoneum after CO₂ pneumoperitoneum used in laparoscopic surgery is examined. Methods: A CO₂ pneumoperitoneum with an intraperitoneal pressure of 6 mmHg was applied for 30 min in 32 nude mice. In the course of 4 days, the animals were killed and the peritoneal surface of the abdominal wall was studied by means of scanning electron microscopy. Results: Already 2 h after release of the pneumoperitoneum, mesothelial cells were bulging up. The intercellular clefts thereby increased in size, and the underlying basal lamina became visible. This reaction peaked after 12 h. Subsequently, peritoneal macrophages and lymphocytes filled all gaps, thereby recovering the basal lamina. Conclusion: The morphologic integrity of the peritoneum is temporarily disturbed by a CO₂ pneumoperitoneum. Received: 9 March 1998/Accepted: 24 July 1998     

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

Background: 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. Methods: 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. Results: 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 10mmHg (p < 0.001 and p < 0.01, respectively). Conclusions: 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.     

Duration of postlaparoscopic pneumoperitoneum

Background: Patients who present with abdominal pain after recent laparoscopic surgery present a diagnostic dilemma when pneumoperitoneum is present. Previous studies do not define the duration of postlaparoscopic pneumoperitoneum. In this study, we attempted to define the duration of laparoscopic pneumoperitoneum and to identify factors which affect resolution time. Methods: We followed 57 patients who underwent laparoscopic cholecystectomy (34), inguinal herniorraphy (20), or appendectomy (three). Serial abdominal films were taken until all residual gas was resolved. Results: Thirty patients resolved their pneumoperitoneum within 24 h; 16 patients resolved between 24 h and 3 days; nine patients resolved between 3 and 7 days; two patients resolved between 7 and 9 days. Mean resolution time for all patients was 2.6 ± 2.1 days. There was no apparent difference in resolution time between the three types of procedures; however, the sample size may be insufficient. Duration of the pneumoperitoneum did not correlate with gender, age, weight, initial volume of CO₂ used, length of time for the procedure, or postoperative complications. Sixteen patients had bile spillage during cholecystectomy which significantly reduced the duration of postoperative pneumoperitoneum (p < 0.008), resulting in a mean resolution time of 1.3 ± 0.9 days. While 14 patients reported postoperative shoulder pain, no correlation was found between the presence or duration of shoulder pain and the extent or duration of pneumoperitoneum. Conclusions: We conclude that the residual pneumoperitoneum following laparoscopic surgery resolves within 3 days in 81% of patients and within 7 days in 96% of patients. The resolution time was significantly less in patients sustaining intraoperative bile spillage during cholecystectomy. There was no correlation found between postoperative shoulder pain and the presence or duration of the pneumoperitoneum. Received: 22 March 1996/Accepted: 12 July 1996     

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     

The effects of pneumoperitoneum on gastric blood flow and traditional hemodynamic measurements

Background: The purpose of this study was to investigate the effects of increasing intraabdominal pressure (IP) on gastric blood flow, as measured by gastric tonometry and traditional hemodynamic measurements. Methods: Nine swine were anesthetized, intubated, and ventilated. Arterial and pulmonary artery catheters were placed by cutdown, a trocar was placed in the abdomen, and a gastric tonometer was placed in the stomach. Serial measurements of arterial and mixed venous blood gases, cardiac output, wedge pressure, lactic acid, and gastric intramucosal pH (pH_i) were collected at intraperitoneal pressures of 0, 8, 10, 12, 14, 16, and 18 mm Hg after 30 min equilibration. Statistical analysis included Pearson correlation and Student's t test. Results: Increasing levels of IP were correlated with decreased arterial pH (p < 0.00003), increased mixed venous CO₂ (p < 0.003), decreased intramucosal pH (p < 0.014), and increased arterial CO₂ (p < 0.015). Gastric pH_i differed significantly from baseline at IP levels of 16 mm Hg (p < 0.004) and 18 mm Hg (p < 0.01). No significant effects were observed on cardiac output or arterial lactate. No significant effects were observed in a control group that had been insufflated to 8 mm Hg and held constant over 3 h. Conclusions: In this model, gastric blood flow is adversely affected by increasing IP with pronounced effects in excess of 15 mm Hg. These results suggest that gastric tonometry may be used to monitor the adverse effects of pneumoperitoneum. Gastric pH_i may be an earlier indicator of altered hemodynamic function during laparoscopy than traditional measures. Received: 25 March 1997/Accepted: 30 June 1997     

腹腔镜胆囊切除术中二氧化碳气腹对脑血流的影响

目的 观察腹腔镜期间二氧化碳气腹对患者脑血流的影响。方法 选择行腹腔镜胆囊切除术患者３０例,ＡＳＡⅠ～Ⅱ级、于气腹前、气腹后１０、３０ｍｉｎ分别采取桡动脉血管颈内静脉血,测定ＰａＯ２、ＰａＣＯ２、ＳａＯ３、颈内静脉血氧分压（ＰｉｖＯ２）和血氧和度（ＳｕｖＯ２）等值。结果与气腹前比较,气腹后１０ｍｉｎ、３０ｍｉｎ的ＳｕｖＯ２、颈内静脉血氧含量（ＣｕｖＯ２）和ＰａＣＯ２无显著性增加（Ｐ〈０．０１）,脑     

Hemodynamic changes in the inferior caval vein during pneumoperitoneum

Background: Laparoscopic procedures of increasing difficulty and duration are becoming more and more common. This may cause significant challenges to the circulatory system and possibly influence thrombogenicity. Methods: Experimental study of carbon dioxide pneumoperitoneum in pigs. Results: Inferior caval vein blood flow remained unchanged, whereas inferior caval vein pressure increased during pneumoperitoneum. Inferior caval vein, pulmonary, and systemic vascular resistance increased during pneumoperitoneum and remained increased after exsufflation. Conclusions: Pneumoperitoneum leads to an increased inferior caval vein pressure, which could cause a dilation of peripheral veins. The similar patterns of vascular resistance in the inferior caval vein, pulmonary artery, and systemic arteries (a gradual increase remaining elevated after exsufflation) suggest a common humoral factor or increased sympathetic nerve activity. Received: 2 April 1996/Accepted: 7 June 1996     

Oxidative stress in lung tissue induced by CO2 pneumoperitoneum in the rat

Background: Clinical trials have found that the pneumoperitoneum has potentially hazardous side effects. The biochemical basis of organ injury induced by pneumoperitoneum is, however, not well defined. Since oxidative stress is believed to play an important role in many pathological conditions, we set out to examine oxidative stress markers in the lung, liver, kidney, and pancreas by using a rat model of laparoscopy with CO₂ pneumoperitoneum and comparing it to a group with gasless laparoscopy. Methods: Malondialdehyde (for lipid peroxidation), protein-bound carbonyls (for protein oxidation), reduced and oxidized glutathione, and the neutrophil marker myeloperoxidase were evaluated in tissue homogenates at 2 h, 6 h, and 18 h after laparoscopy. Immunoblotting was used to analyze the modification of lung proteins by 4-hydroxynonenal at 6 h. Results: Significant lipid peroxidation was found selectively in lungs at 2 h and 6 h after CO₂ pneumoperitoneum. This was accompanied by a loss of glutathione but only minor protein oxidation. Further, lung proteins were clearly modified by the aldehydic product of lipid peroxidation 4-hydroxynonenal. Myeloperoxidase in lungs increased continuously up to 18 h in both experimental groups, but there were higher levels in the group with pneumoperitoneum. Conclusion: Oxidative stress is likely to contribute to the impairment of pulmonary function after laparoscopic operations using a CO₂ pneumoperitoneum. Received: 22 November 1999/Accepted: 22 March 2000/Online publication: 10 July 2000     

Effects of peritoneal insufflation on hepatic and renal blood flow

The effects of peritoneal insufflation with carbon dioxide on hepatic and renal blood flow have not been reported hitherto. We evaluated these effects in a porcine model of abdominal laparoscopic surgery. Seven anesthetized pigs underwent peritoneal insufflation in a step-wise manner to create intraabdominal pressures of 6, 12, 18 and 24 mmHg, and changes in the arterial and venous pressure, arterial blood gases, and hepatic and renal blood flow were monitored. Both the hepatic and renal blood flow decreased as the intraabdominal pressure increased. Therefore, in order to carry out laparoscopic abdominal surgery safely in patients with hepatic or renal impairment, low intraabdominal pressures or noninsufflating techniques are recommended.     

Hemodynamic effects of helium vs carbon dioxide pneumoperitoneum in an experimental model of acute heart failure

Background  The systemic absorption of carbon dioxide (CO₂) during abdominal insufflation can lead to hypercarbia and acidosis, which contribute to the systemic hemodynamic effects of the pneumoperitoneum (PnP). In several animal and clinical studies, the use of helium (He) as a substitute for CO₂ prevented the development of hypercarbia. One of the common comorbid conditions in which the use of a CO₂ PnP may cause adverse effects is heart failure. The aim of our study was to evaluate and compare the hemodynamic effects of CO₂ and He PnP in an animal model of acute heart failure (AHF). Methods  Hemodynamic and blood gas parameters were measured in 10 domestic pigs during two periods of He and CO₂ insufflation of 30 min duration each, with a 30-min stabilization period between insufflations. The model of AHF was created by sodium pentobarbital injections, and measurements were repeated with both CO₂ and He PnP. The animals were ventilated with constant minute ventilation. Results  Cardiac output had a tendency to decrease during PnP, but these changes were more pronounced with CO₂ PnP in normal the heart (from 2.84±0.65 to 2.18±0.68 L/min, p=0.06) and with He PnP during AHF (from 1.78 ±0.49 to 1.32±0.34 L/min, p=0.016). Systemic vascular resistance increased in every insufflation, but this elevation was not statistically significant. CO₂ and He insufflation caused significant increase of PaCO₂ in the nonfailed heart. During AHF, He insufflation did not elevate PaCO₂. Conclusions  In an experimental model of acute heart failure, insufflation with He did not have any advantage over CO₂. The hemodynamic response to CO₂ and He PnP during normal conditions and under conditions of failed cardiac function support the hypothesis that the hemodynamic response to PnP is a result of a combination of pressure and CO₂ absorption; Furthermore, it appears that increased intraabdominal pressure is the more crucial factor. Online publication: 7 May 2001 Presented in poster format at the annual meeting of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES), San Antonio, TX, USA. 24–27 March 1999     

Morphological changes in hepatic vascular endothelium after carbon dioxide pneumoperitoneum in a murine model

Background: Liver metastasis is an important prognostic factor in advanced colorectal cancer. Several studies have demonstrated that carbon dioxide (CO₂) pneumoperitonem enhances liver metastasis in an animal model. In the present study, we used scanning electron microscopy (SEM) to investigate morphological changes in hepatic vascular endothelium after CO₂ pneumoperitoneum in a murine model.Methods: Thirty-three male BALB/c mice were randomized to undergo pneumoperitoneum (CO₂, air, or helium ), open laparotomy, and anesthesia alone. After each procedure, the animals’ livers were excised at days 0, 1, and 3 and examined by SEM.Results: In the CO₂ pneumoperitoneum group, we observed rough surface and derangement of the hepatic vascular endothelial cells and intercellular clefts on day 1. In the other groups, no major morphologic changes were observed at any time.Conclusions: Hepatic vascular endothelium changes after CO₂ pneumoperitoneum. Such characteristic changes may play an important role in establishing liver metastasis after CO₂ pneumoperitoneum.