The clinical impact of warmed insufflation carbon dioxide gas for laparoscopic cholecystectomy

Background: Reports suggest that the insufflation of cold gas to produce a pneumoperitoneum for laparoscopic surgery can lead to an intraoperative decrease in core body temperature and increased postoperative pain. Methods: In a randomized controlled trial with 20 patients undergoing laparoscopic cholecystectomy, the effect of insufflation using carbon dioxide gas warmed to 37°C (group W) was compared with insufflation using room-temperature cold (21°C) gas (group C). Intraoperative body core and intra-abdominal temperatures were determined at the beginning and end of surgery. Postoperative pain intensity was evaluated using a visual analog scale and recording the consumption of analgesics. Results: There were no significant group-specific differences during the operation, neither in body temperature (group W: 36.1 ± 0.4°C vs group C: 35.7 ± 0.6°C) nor in intra-abdominal temperature (group W: 35.9 ± 0.3°C vs group C: 35.6 ± 0.6°C). Postoperatively, the two groups did not differ in pain susceptibility and need of analgesics. Conclusion: The use of carbon dioxide gas warmed to body temperature to produce a pneumoperitoneum during short-term laparoscopic surgery has no clinically important effect. Received: 13 August 1999/Accepted: 24 September 1999/Online publication: 9 August 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     

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     

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 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 adverse hemodynamic effects of laparoscopic cholecystectomy

Recent studies suggest that significant physiologic derangements can occur during laparoscopic surgery. Eighteen patients admitted for laparoscopic cholecystectomy were studied. The mean age was 46.7 (range 19–78). A standard anesthetic technique, reverse Trendelenburg positioning, and an abdominal insufflation pressure of 15 mmHg with CO₂ were used with all subjects. Central venous pressure (CVP) and arterial pressures were measured invasively. Stroke volume and cardiac index were calculated using quantitative transesophageal echocardiography. Baseline measurements were taken after induction. Additional measurements were taken at 15-min intervals throughout the procedure. There was a statistically significant increase in mean arterial pressure (15.9%), systolic blood pressure (11.3%), diastolic blood pressure (19.7%), and CVP (30.0%) from control baseline values. Significant decreases in stroke volume (29.5%) and cardiac index (29.5%) occurred within 30 min of the induction of pneumoperitoneum and positioning (P<0.05, ANOVA). Laparoscopic cholecystectomy significantly and reversibly decreases cardiac performance. Compromised patients may be at increased risk for complications not previously recognized with this procedure.     

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     

Lack of neurohumoral response to pneumoperitoneum for laparoscopic cholecystectomy

Background: Pneumoperitoneum (PP) for laparoscopic surgery induces prompt changes in circulatory parameters. The rapid onset of these changes suggests a reflex origin, and the present study was undertaken to evaluate whether release of vasopressor substances could be responsible for these alterations. The influence of two different anesthesia techniques was also evaluated. Methods: American Society of Anesthesiologists (ASA) class I patients, scheduled for laparoscopic cholecystectomy, were investigated. The first group (n= 10) was anesthetized intravenously. The second group (n= 6) had inhalation anesthesia. Plasma vasopressin, catecholamines, and plasma renin activity were investigated as neurohumoral vasopressor markers of circulatory stress. The general stress response to surgery was assessed by analysis of plasma cortisol. Results: Induction of pneumoperitoneum caused no apparent activation of vasopressor substances, although several hemodynamic parameters responded promptly. Conclusion: The hemodynamic alterations, seen at the establishment of PP during stable anesthesia, cannot be explained by elevation of vasopressor substances in circulating blood. Received: 7 April 1997/Accepted: 3 December 1997     

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     

Time-related changes in hemodynamic parameters and pressure-derived indices of left ventricular function in a porcine model of prolonged pneumoperitoneum

Background: Advanced laparoscopic procedures require prolonged pneumoperitoneum. Increased intra-abdominal pressure causes a number of hemodynamic changes including a drop in cardiac output, but it is unclear whether there is a direct effect on cardiac contractility. In this experimental study, we sought to determine whether there is a direct impact of pneumoperitoneum on cardiac contractility. We also examined the time-related changes taking place during the insufflation period. Methods: Six young pigs were anesthetized and mechanically ventilated. Pneumoperitoneum was established by insufflating carbon dioxide to a pressure of 15 mmHg and maintained for a period of 180 min. Hemodynamic parameters including left ventricular dP/dT were invasively recorded every 15 min. All hemodynamic changes were statistically evaluated, and parameters were correlated with time. Results: Cardiac output decreased with insufflation from a baseline of 3.37 ± 0.34 lt/min and reached the lowest value at 165 min of pneumoperitoneum (2.86 ± 0.30 l/min; p= 0.023). Systemic vascular resistance (SVR) significantly increased from 2236 ± 227 dyne/s/cm⁵ to a maximum of 3774 ± 324 dyne/s/cm⁵ (p= 0.005). Left ventricular dP/dT maximum did not change significantly with insufflation. The decrease in cardiac output strongly correlated with the increase in SVR (r=−0.949). Time of insufflation correlated with cardiac output (r=−0.762) and dP/dT maximum (r=−0.727). Conclusions: Pneumoperitoneum at 15 mmHg negatively affects cardiac output without significantly affecting cardiac contractility. A significant increase in SVR appears to be the driving event for the decreased cardiac output. Prolonged pneumoperitoneum may have an additional negative effect on hemodynamic parameters. Received: 5 January 2000/Accepted: 4 May 2000/Online publication: 26 July 2000     

Hemodynamic changes during laparoscopic cholecystectomy monitored with transesophageal echocardiography

Although pneumoperitoneum has been well tolerated in a predominantly healthy population, there is concern that an increased intraperitoneal pressure may be poorly tolerated in patients with marginal cardiopulmonary function. The purpose of this study was to demonstrate noninvasively the hemodynamic effects of carbon dioxide pneumoperitoneum utilizing biplane transesophageal echocardiography.Fourteen otherwise-healthy patients undergoing nonemergent laparoscopic cholecystectomy were studied using bi-plane transesophageal echocardiography under a standardized anesthetic protocol utilizing isoflurane, fentanyl, and vecuronium bromide. Endtidal CO₂, oxygen saturation, cardiac rhythm, temperature, and blood pressure were monitored noninvasively. Minute ventilatory volume was adjusted as needed to keep end-tidal CO₂ less than 38 mmHg. Data were recorded at baseline, following abdominal insufflation to 15 mmHg with CO₂, with head-up tilt of 20°, following exsufflation, and with the patient level. Significance was determined using a paired Student t-test.Insufflation to 15 mmHg decreased cardiac index (C.I.) by 3% (3.34 to 3.23 l/min/m²) while both heart rate (HR) and mean arterial pressure (MAP) increased (by 7% and 16%), respectively, and stroke volume index decreased by 10% (from 51.6 to 46.6 ml/beat/m²). Head-up tilt of 20° further decreased CI to 2.98 l/min/m² (–11%) and SVI to 40.3 ml/beat/m² (–22%) while HR increased by a total of 14% and MAP by 19%.As laparoscopic techniques are applied to a broader population, the impact of small but significant decrements in cardiac function become increasingly important. This study demonstrates that the combination of CO₂ pneumoperitoneum and the reverse Trendelenburg position does adversely effect cardiac output.Presented at the annual meeting of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES), Nashville, Tennessee, USA, 18–19 April 1994     

Combined intraoperative laparoscopic cholecystectomy and endoscopic retrograde cholangiopancreatography

Background: The role and timing of endoscopic retrograde cholangiopancreatography (ERCP) in patients with suspected choledocholethiasis remains a controversial subject. There have been few studies exploring the role of intraoperative ERCP. Therefore, we set out to perform a retrospective review of 29 patients who underwent combined laparoscopic cholecystectomy (LC) and intreoperative ERCP (LC/ERCP). Our objective was to assess the feasibility of a one-stage approach using intraoperative ERCP. Methods: We identified 29 patients in whom LC/ERCP was attempted between January 1996 and November 1998 at a university-affiliated hospital with a large private faculty. Parameters reviewed included preoperative diagnosis, liver function tests (LFT), finding on transcystic cholangiogram (TCC), ERCP, stone retrieval, failure of ERCP, length of stay, morbidity, and mortality. Results: Twenty-eight of 29 patients (97%) underwent successful combined LC/ERCP. Successful TCC followed by ERCP was performed in 21 of 26 patients (81%). Five TCC were technically unsuccessful; in these patients, ERCP was performed on the basis of preoperative criteria. In three patients, TCC was not attempted. Stones were successfully retrieved from 20 of 21 patients (95%) with abnormal finding on TCC, one of five patients (20%) with failed TCC, and two of three patients (67%) with ERCP but without TCC. Overall morbidity was 14%, comprising two patients with postoperative hyperamylasemia and two with cystic duct leaks. There were no deaths in the group. The mean time for the combined procedure was 173 min (range, 50–290). Mean length of hospitalization was 3.4 days, and mean postoperative stay was 2.2 days. Conclusions: LC/ERCP can be performed safely. The advantages of the combined procedures include one-stage treatment of cholelithiasis and choledocholithiasis, avoidance of unnecessary preoperative ERCP and their concomitant complications, and elimination of potential return to the operating room when postoperative ERCP is technically impossible. Received: 3 February 1999/Accepted: 10 September 1999     

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     

The outcome of major biliary tract injury with leakage in laparoscopic cholecystectomy

Background: Concern has been expressed regarding the increased rates of biliary tract injury (BTI) at laparoscopic cholecystectomy. The aim of the present investigation was to analyze the outcome of laparoscopic biliary tract injury with leakage. Methods: Sixteen patients having major laparoscopic BTI with leakage were treated. Thirteen of them were referred to our institution for further treatment. The follow-up was complete and focused on clinical outcome and biochemical analysis. Results: Eight BTI were identified at the time of laparoscopic cholecystectomy, and the procedure was converted to a laparotomy. In eight additional patients, BTI was recognized postoperatively. In this group one patient died because of lately diagnosed biliary peritonitis, whereas in the seven surviving patients nine attempts to repair the BTI and eight other interventions were performed. In the conversion group 14 attempts to repair the BTI and 11 other interventions were needed to completely solve the problems. Final restoration of the BTI was done by Roux-en-Y hepaticojejunostomy in 11 patients and suture repair with T-tube drainage of the bile duct in 4. During a median follow-up time of 63 months, three patients suffered from recurrent segmental cholangitis. In the other patients, neither clinical nor biochemical evidence of biliary disease has been found up to this writing. Conclusions: Laparoscopic BTI has a high morbidity and mortality rate that seems comparable to BTI at open cholecystectomy. The number of attempts to repair the BTI as well as additional interventions is too high, but in this patient series the final outcome seemed to be similar after BTI recognized during and after laparoscopic cholecystectomy. Received: 3 December 1997/Accepted: 28 May 1998     

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     

Effects of carbon dioxide vs helium pneumoperitoneum on hepatic blood flow

Background: Elevated intraabdominal pressure due to gas insufflation for laparoscopic surgery may result in regional blood flow changes. Impairments of hepatic, splanchnic, and renal blood flow during peritoneal insufflation have been reported. Therefore we set out to investigate the effects of peritoneal insufflation with helium (He) and carbon dioxide (CO₂) on hepatic blood flow in a porcine model. Methods: Twelve pigs were anesthetized and mechanically ventilated with a fixed tidal volume after the stabilization period. Peritoneal cavity was insufflated with CO₂ (n= 6) or He (n= 6) to a maximum intraabdominal pressure of 15 mmHg. Hemodynamic parameters, gas exchange, and oxygen content were studied at baseline, 90 mm and 150 min after pneumoperitoneum, and 30 min after desufflation. Determination of hepatic blood flow with indocyanine green was made at all measured points by a one-compartment method using hepatic vein catheterization. Results: A similar decrease in cardiac output was observed during insufflation with both gases. Hepatic vein oxygen content decreased with respect to the baseline during He pneumoperitoneum (p < 0.05), but it did not change during CO₂ insufflation. Hepatic blood flow was significantly reduced in both the He and CO₂ pneumoperitoneums at 90 min following insufflation (63% and 24% decrease with respect to the baseline; p < 0.001 and p < 0.05, respectively) being this decrease marker in the He group (p= 0.02). Conclusions: These findings suggest that helium intraperitoneal insufflation results in a greater impairment on hepatic blood flow than CO₂ insufflation. Received: 27 March 1996/Accepted: 19 January 1997     

Hemodynamic and pulmonary changes during and after laparoscopic cholecystectomy

Background: The cardiopulmonary changes experienced by patients who undergo laparoscopic cholecystectomy (LC) and the prognostic value of patient characteristics are not well understood. Methods: Cardiorespiratory changes were investigated in 120 patients undergoing LC or open cholecystectomy (OC). The results and their relation to patient variables were statistically evaluated. Results: The most significant cardiorespiratory changes were (A-a)PO₂ increase during OC; decrease of pH and compliance and increase of peak airway pressure during LC; impairment of arterial blood gas mean values and respiratory muscle strength; atelectasis and pneumonia (five cases) after OC; and lamellar atelectasis (two cases) after LC. Significant adverse prognostic factors related to intra- and postoperative LC cardiorespiratory changes were ASA class greater than I, FEF_75–85% < 900 ml, and PaO₂ < 10.4 kPa (PPV, 71.4% and 46.6%, respectively). Conclusions: LC carries no significant cardiorespiratory changes provided that intraoperative monitoring of hemodynamics and respiratory parameters is done for the study of blood gas values in all patients at risk.     

Coincidental finding of hepatic carcinoid micrometastases during routine laparoscopic cholecystectomy

A case of a coincidental finding of hepatic carcinoid micrometastases, barely visible to the eye, during routine laparoscopic cholecystectomy is reported. The micrometastases were possibly recognized as a result of a beneficial aspect of laparoscopic surgery, namely the >10× enlargement of tissue/pathologic structures. Received: 16 August 1996/Accepted: 28 February 1997     

Hemodynamic consequences of high- and low-pressure capnoperitoneum during laparoscopic cholecystectomy

Background: Peritoneal insufflation to 15 mmHg diminishes venous return and reduces cardiac output. Such changes may be dangerous in patients with a poor cardiac reserve. The aim of this study was to investigate the hemodynamic effects of high (15 mmHg) and low (7 mmHg) intraabdominal pressure during laparoscopic cholestectomy (LC) Methods: Twenty patients were randomized to either high- or low-pressure capnoperitoneum. Anesthesia was standardized, and the end-tidal CO₂ was maintained at 4.5 kPa. Arterial blood pressure was measured invasively. Heart rate, stroke volume, and cardiac output were measured by transesophageal doppler. Results: There were 10 patients in each group. In the high-pressure group, heart rate (HR) and mean arterial blood pressure (MABP) increased during insufflation. Stroke volume (SV) and cardiac output were depressed by a maximum of 26% and 28% (SV 0.1 > p > 0.05, cardiac output p > 0.1). In the low-pressure group, insufflation produced a rise in MABP and a peak rise in both stroke volume and cardiac output of 10% and 28%, respectively (p < 0.05). Conclusions: Low-pressure pneumoperitoneum is feasible for LC and minimizes the adverse hemodynamic effects of peritoneal insufflation. Received: 23 May 1997/Accepted: 11 March 1998     

Laparoscopic cholecystectomy and time-course changes in renal function

Background: Recently, the retraction method has been used to reduce intraabdominal pressure (IAP) during laparoscopic surgery. The purpose of this study was to determine the serial changes in renal function during laparoscopic cholecystectomy (LC) using the retraction method. Methods: Urine output, effective renal plasma flow (ERPF), and glomerular filtration rate (GFR) were measured serially in seven patients who underwent LC with 12 mmHg pneumoperitoneum (High-IAP group) and five who underwent LC using the retraction method with 4 mmHg pneumoperitoneum (Low-IAP group). Results: Urine output, ERPF, and GFR were decreased during pneumoperitoneum in the High-IAP group, whereas no significant changes in any of these parameters were observed in the Low-IAP group. Conclusions: Our findings demonstrate that reduction of IAP to 4 mmHg using the retraction method prevents the transient renal dysfunction caused by prolonged 12 mmHg pneumoperitoneum during LC, suggesting that the retraction method reduces the risk of perioperative renal dysfunction during laparoscopic surgery. Received: 26 March 1996/Accepted: 27 July 1996