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     

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     

Prolonged pneumoperitoneum at 15 mmHg causes lactic acidosis

Background: Acute increases in intraabdominal pressure (IAP) induce systemic and regional circulatory changes. Besides, mechanical compression on the capillary beds may decrease oxygen availability to the tissues. The purpose of this clinical study was to analyze the effects of increased IAP on acid-base disturbances and plasma lactate levels during prolonged carbon dioxide pneumoperitoneum. Methods: Twenty-eight patients undergoing laparoscopic sigmoidectomy were included in this study. Fourteen of them (group A) had IAP of 15 ± 1 mmHg while the remaining 14 (group B) had IAP of 10 ± 1 mmHg. The control group included six patients undergoing conventional sigmoidectomy. Results: A progressive significant increase in PaCO₂ was observed in the laparoscopic groups (p < 0.01). Plasma lactate levels in group A significantly increased 90 min after insufflation (p < 0.05) and reached the highest value 1 h after deflation (9.9 ± 1 vs 31.9 ± 2.5 mg/dl, p < 0.005). Simultaneously, arterial pH decreased in all groups; however, at 1 h after surgery, it was significantly lower (p= 0.02) in group A. There was a significant correlation between acid concentration due to lactate and lactate concentration (GA: R ²= 0.717, p= 0.03; GB: R ²= 0.879, p= 0.006 and GC: R ²= 0.853, p= 0.008). Conclusion: High IAP causes lactic acidic accumulation in patients undergoing prolonged laparoscopic procedures. Received: 1 April 1996/Accepted: 19 November 1996     

Newly designed retraction devices for intestine control during laparoscopic aortic surgery

Background: Recent clinical studies have demonstrated the feasibility of laparoscopic surgery for aortic occlusive and aneurysmal disease. However, transperitoneal aortic access is compromised by poor exposure in the operative field from uncontrolled bowel. The retractors that are currently available are inadequate for this task. The development of new retractors would help to facilitate laparoscopic aortic surgery. Methods: Six female piglets (28–30 kg) in each group underwent laparoscopy with pneumoperitoneum (12 mmHg). Exposure of the infrarenal aorta and cross-clamping were undertaken through a transperitoneal approach. Two paddles inserted in a polyester bilayer (mobile device, group A) or a mesh net fixed to the abdominal wall (fixed device, group B) were used to retain the bowel. Aortotomy and suturing were performed to mimic a vascular procedure. After bleeding was controlled, the intraabdominal pressure (IAP) was lowered to 6 mmHg, and retraction was assessed for 30 min. The main outcome measures were time to deploy the retractors, time to perform the vascular procedure, time to withdraw the devices, and total procedural time. Blood loss and frequency of retraction failure were also recorded. Results: Mean time to deploy the device was 22 ± 12 min in group A and 36 ± 34 min in group B (n.s.). Vascular surgery time averaged 60 ± 24 min in group A and 68 ± 16 min in group B (n.s.). The times to withdraw the nets were 3.6 ± 1.2 min and 13.5 ± 8.2 min, respectively (p < 0.05). Total surgery time was 155 ± 41 min vs 174 ± 49 min (n.s.). There were six retraction failures, five in group A and one in group B. When lower IAP was used, there was only one failure in each study group. Mean blood loss was <150 ml in both groups. There were no major complications. Conclusions: Both methods provided adequate exposure of the infrarenal aorta. Vascular surgery time and blood loss were similar for both groups. The movable device proved more usable and, at lower IAP, more effective. The results of this study demonstrate effective bowel retraction for laparoscopic aortic surgery. Received: 10 December 1998/Accepted: 13 May 1999     

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     

Measurement of urinary N-acetyl-β-D-glucosaminidase to assess renal ischemia during laparoscopic operations

Background: Oliguria during laparoscopy is a well-documented phenomenon of unknown etiology. Experimental evidence suggests that renal perfusion is reduced during pneumoperitoneum. N-acetyl-β-D-glucosaminidase (NAG), which is present in renal tubular cells, is released into the urine in response to tubular insults. In this study, urinary NAG was measured before and after procedures to assess for ischemic renal injury. Methods: A total of 31 patients underwent laparoscopic procedures while 28 patients had conventional surgery. Urine was obtained first at the time of preoperative Foley catheter placement and later during the recovery room stay. NAG levels were measured and indexed to urinary creatinine. Results: Operative time for the laparoscopy group was 105 min (range, 15–255); for the conventional group, it was 179 min (range, 75–385) (P < 0.05). No differences were noted between pre- and postoperative NAG levels or between the groups. There was no correlation between urinary NAG levels and operative time. Conclusion: Pneumoperitoneum is not associated with a change in the urinary concentration of NAG. This finding suggests that there is no significant renal tubular injury associated with laparoscopic surgery. Accepted: 8 April 1997     

Intracranial pressure

Background: The effects of pneumoperitoneum on intracranial pressure (ICP) have received relatively little attention. This study was undertaken to investigate the changes in ICP occurring as a result of increased intraabdominal pressure (IAP) and positioning in animals with normal and elevated ICP. Method: Five pigs (average weight 60 lb) were studied. A subarachnoid screw was placed for ICP monitoring. End tidal CO₂ was monitored. Ventilation was performed to keep PCO₂ between 30 and 50 mmHg. Measurements of arterial blood gases, mean arterial blood pressure, and ICP were recorded at four different levels of intraabdominal pressure (IAP 0, 8, 16, and 24 mmHg), both in the supine and Trendelenburg positions. A Foley catheter was introduced into the subarachnoid space to elevate the intracranial pressure, and the same measurements were performed. Results: There was a significant and linear increase in ICP with increased IAP and Trendelenburg position. The combination of increased IAP of 16 mmHg and Trendelenburg position increased ICP 150% over control levels. Conclusions: Patient positioning and level of IAP should be taken into consideration when performing laparoscopy on patients with head trauma, cerebral aneurysms, and other conditions associated with increased ICP. Received: 19 March 1996/Accepted: 24 May 1996     

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     

Effect of temperature of insufflated CO2 during and after prolonged laparoscopic surgery

Background: Pneumoperitoneum with room temperature carbon dioxide (CO₂) has been shown to decrease core temperature and urine output. Methods: The effect of 37°C (warm) and room temperature (cool) CO₂ pneumoperitoneum on core temperature, urine output, and central hemodynamics was compared in 26 randomized patients undergoing prolonged laparoscopic surgery (>90 min). Results: The core temperature (p < 0.05) and cardiac index (p < 0.05) were significantly higher after warm than after cool pneumoperitoneum. Urine output was significantly higher during warm (2.3 ± 1.6 ml/kg/h) than during cool (0.9 ± 0.7 ml/kg/h) insufflation (p < 0.05). Two of 13 patients with warm and 11 of 13 patients with cool pneumoperitoneum needed mannitol to maintain adequate diuresis (p < 0.05). Conclusions: Warm insufflation probably causes a local vasodilation in the kidneys and may be beneficial to patients with borderline renal function. Received: 23 June 1997/Accepted: 16 November 1997     

Changing management of gallstone disease during pregnancy

Background: Symptomatic gallstones may be problematic during pregnancy. The advisability of laparoscopic cholecystectomy (LC) is uncertain. The objective of this study is to define the natural history of gallstone disease during pregnancy and evaluate the safety of LC during pregnancy. Methods: Review of medical records of all pregnant patients with gallstone disease at the University of California, San Francisco, from 1980 to 1996. Results: Of approximately 29,750 deliveries, 47 (0.16%) patients were treated for gallstone disease, including biliary colic in 33, acute cholecystitis in 12, and pancreatitis in two. Conservative treatment was attempted in all patients but failed in 17 (36%) cases. Two patients required combined preterm Cesarean-section cholecystectomy and 10 required surgery in the early postpartum period for persistent symptoms. Seventeen patients required cholecystectomy during pregnancy for biliary colic (10), acute cholecystitis (six), and pancreatitis (one). Three patients were treated with open cholecystectomy. Fourteen patients underwent LC at a mean gestational age of 18.6 weeks, mean OR time of 74 min, and mean length of stay of 1.2 days. Hasson cannulation was utilized in 11 patients. Reduced-pressure pneumoperitoneum (6–10 mmHg) was used in seven patients. Prophylactic tocolytics were used in seven patients, with transient postoperative preterm labor observed in one. There were no open conversions, preterm deliveries, fetal loss, teratogenicity, or maternal morbidity. Conclusions: In past years, symptomatic gallstones during pregnancy were managed conservatively or with open cholecystectomy. LC is a feasible and safe method for treating severely symptomatic patients. Received: 3 April 1997/Accepted: 5 July 1997     

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     

Alterations in hepatic function during laparoscopic surgery

Background: Very few studies have been done on the consequences of pneumoperitoneum on hepatic function. At present, there is no consensus on the physiopathological hepatic implications of pneumoperitoneum. The purpose of this clinical study was to evaluate the effects of pneumoperitoneum on hepatic function in 52 patients treated with laparoscopic procedures. Methods: Thirty-two laparoscopic cholecystectomies and 20 nonhepatobiliary laparoscopic procedures were performed in 52 patients (12 men and 40 women) with a mean age of 44 years (range, 15–74). All patients had normal values on preoperative liver function tests. The anesthesiologic protocol was uniform, with drugs at low hepatic metabolism. The 32 cholecystectomies were randomized into 22 performed with pneumoperitoneum at 14 mmHg and 10 performed at 10 mmHg. All nonhepatobiliary laparoscopic procedures were performed with a pneumoperitoneum of 14 mmHg. The postoperative serologic levels of AST, ALT, bilirubin, and prothrombin time were measured at 6, 24, 48, and 72 h. The serologic changes were related to the procedure, the duration, and the level of pneumoperitoneum. Results: Mortality and morbidity were nil. All 52 patients had a postoperative increase in AST, ALT, bilirubin, and lengthening in prothrombin time. Slow return to normality occurred 48 or 72 h after operation. The increase of AST and ALT was statistically significant and correlated both to the level (10 versus 14 mmHg) and the duration of pneumoperitoneum. Conclusions: The duration and level of intraabdominal pressure are responsible for changes of hepatic function during laparoscopic procedures. Although no symptom appears in patients with normal hepatic function, patients with severe hepatic failure should probably not be subjected to prolonged laparoscopic procedures. Received: 23 May 1997/Accepted: 28 October 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     

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     

Lactate metabolism during laparoscopic cholecystectomy: comparison between CO2 pneumoperitoneum and abdominal wall retraction

Recent reports have implicated CO₂ pneumoperitoneum for laparoscopic surgery in the occurrence of postoperative mesenteric ischemia. With this kind of surgery, the increase in blood lactate levels has been attributed to anaerobic metabolism, probably due to tissue ischemia induced by high intraabdominal pressure (IAP). The aim of this study was to evaluate the metabolic repercussion of CO₂ pneumoperitoneum during laparoscopic cholecystectomy (LC). This was a prospective randomized study of CO₂ pneumoperitoneum (PP group, n= 19) versus abdominal wall retraction (AWR group, n= 15). Demographic data were collected preoperatively. Four-trocar LC was performed with either a CO₂ pneumoperitoneum (IAP of 12 mmHg) or abdominal wall retraction (abdominal wall pressure 6–10 kp). Intraoperative and postoperative blood samples were collected and lactate levels determined by enzymatic analysis. Repeated measures analysis of variance (MANOVA) was used for statistical analysis. Significance was evaluated at p < 0.05. The groups were shown to be homogeneous. Lactate concentration, expressed as mean (SD), went from 25.4 (14.4) mg/dl at baseline to 18.9 (13.6) mg/dl 4 hours after surgery in the PP group and from 19.4 (6.1) mg/dl at baseline to 17.8 (14.7) mg/dl in the AWR group. No significant differences were found between groups intraoperatively (p= 0.116) or postoperatively (p= 0.99). Our study did not show significant differences in blood lactate levels during LC with CO₂ pneumoperitoneum compared to the same procedure with abdominal wall retraction.     

Pneumoperitoneum with carbon dioxide enhances liver metastases of cancer cells implanted into the portal vein in rabbits

Background: Little is known about the role of the CO₂ pneumoperitoneum on tumor cells that spread from the portal system into the liver during laparoscopic surgery for gastrointestinal malignancies. Therefore, we designed a study to investigate the effect of CO₂ pneumoperitoneum on cancer cells implanted in the portal vein in a rabbit model. Methods: Immediately after intraportal inoculation of 2.5 × 10⁵ cells of VX₂ cancer, the rabbits received either CO₂ pneumoperitoneum at a pressure of 10 mmHg for 30 min (pneumoperitoneum group, n= 14) or laparotomy alone for 30 min (laparotomy group, n= 14). Results: The number (p < 0.01) and area of cancer nodules (p= 0.045) on the liver surface on day 17 were greater in the pneumoperitoneum group than in the laparotomy group. The frequency of cancer nodules >3.0 mm in diameter was higher in the pneumoperitoneum group than in the laparotomy group (p < 0.001). Conclusions: Compared with laparotomy, CO₂ pneumoperitoneum enhanced the development of liver metastases in this experimental model. Received: 9 December 1998/Accepted: 3 April 1999     

Comparison of the stress response after laparoscopic and open cholecystectomy

Background: We designed a prospective controlled animal study to compare the stress response induced after laparoscopic and open cholecystectomy. Methods: Twelve female pigs (20–25 kg body weight) were anesthetized with ketamine, pentobarbital, and fentanyl. The animals were randomized into the following four groups: control (C), pneumoperitoneum with CO₂ at 14–15 mmHg (P), laparoscopic cholecystectomy (LC), and open cholecystectomy (OC). The average duration of the procedure in each group was 35 min. Results: Central venous pressure, mean arterial pressure, pulmonary capillary wedge pressure, and cardiac output were monitored. Measurements were recorded when animals were anesthetized (baseline), immediately before and after surgery, and thereafter every 30 min for a maximum of 3 h. White blood cell count (WBC) was determined from blood samples taken before and after 3 h of surgery. Ultrasound-guided liver biopsies were done preoperatively and after 3 h of surgery. Total RNA was isolated from the liver biopsy specimens. Steady-state mRNA levels of β-fibrinogen (β-fib), α 1-chymotrypsin inhibitor (α1-CTI), metallothionein (MT), heat shock protein 70 (Hsp70), and polyubiquitin (Ub) were detected by Northern blot/hybridization. There were no statistical differences in the hemodynamic parameters among the groups. The number of circulating neutrophils and monocytes decreased only after LC. Expression of Hsp70 was not induced after any surgical procedure, and the mRNA levels of Ub did not change after surgery. The expression of α1-CTI and β-fib (acute phase genes) were similarly increased after LC and OC. Steady-state mRNA levels of MT were slightly increased after P and LC but not after OC. Conclusion: These data indicate that there are no significant differences between LC and OC in terms of induction of the stress response. Received: 19 March 1999/Accepted: 2 July 1999/Online publication: 20 September 2000     

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     

Influence of acute hemorrhage and pneumoperitoneum on hemodynamic and respiratory parameters

Background: We examined the questions of whether resuscitated (compensated) acute hemorrhage enhances the negative effects of carbopneumoperitoneum on hemodynamic and respiratory parameters and whether pneumoperitoneum with helium has any advantages under these circumstances. Our investigation focused on the influence of acute hemorrhage with different gases on the cardiovascular and respiratory system as well as on hepatic and renal blood flow in a porcine model. Methods: Cardiac and hemodynamic function were monitored via implantation of catheters in pulmonary artery, femoral vein, and artery. Renal and hepatic blood flow were recorded using a transonic volume flow meter placed at the renal and hepatic artery and portal vein. Twelve animals were randomly assigned to one insufflation gas (carbon dioxide [CO₂] or helium [He]). Following baseline recordings, acute hemorrhage (20 ml/kg) was induced by continuous bleeding over 30 min. Animals then received a colloidal solution (20 ml/kg 6% hydroxyethylstarch solution) over 30 min. Pneumoperitoneum of 12 mmHg was established, and all parameters were measured after 30 min of adaptation. The major endpoints of the study were cardiac output (CO), arterial pressure (MAP), systemic vascular resistance (SVR), and central venous pressure (CVP), as well as blood flow in hepatic and renal artery and portal vein. Results: While CO and hemodynamic parameter as well as hepatic and renal blood flow were markedly reduced after hemorrhage, they returned nearly to their previous levels after resuscitation. Pneumoperitoneum with 12 mmHg did not further depress the cardiovascular system or reduce hepatic and renal blood flow. Pneumoperitoneum did not alter hepatic or renal blood flow. Pneumoperitoneum with helium did not substantially change the reaction of the cardiovascular system after resuscitated hemorrhage. Conclusions: If hemorrhage is compensated by proper resuscitation and hypovolemia is avoided, laparoscopic surgery with pneumoperitoneum of 12 mmHg appears to be not harmful. Using helium as the insufflating gas had no clear advantage over the carbon dioxide model. Received: 30 July 1997/Accepted: 24 October 1997     

Laparoscopic surgery during pregnancy

Background: Laparoscopic surgery is known for its many advantages, but the use of this modality during pregnancy is still under discussion. Methods: The subjects in this discussion are the unknown influence of the pneumoperitoneum and the fear of damaging the uterus while inserting the Veress needle and trocars. In a review of recent literature describing laparoscopic surgery during pregnancy, no complications were seen. We performed four laparoscopic appendectomies and three laparoscopic cholecystectomies between 12 and 33 weeks estimated gestational age (EGA). Results: All pregnancies passed without complications and ended in at-term deliveries of healthy babies. Conclusions: The risks, precautions to avoid them, and the safety of laparoscopic surgery during pregnancy are discussed in the light of our experience and reports in recent literature. Received: 26 September 1995/Accepted 3 May 1996