Loss of physiologic hepatic blood flow control ("hepatic arterial buffer response") during CO2-pneumoperitoneum in the rat

What is the ideal preconditioning time to reduce laparoscopic-induced oxidative stress?

Introduction

Ischaemic preconditioning is the most effective method for the prevention of ischaemic-reperfusion injury; however, no study has examined the question of the ideal time for ischaemic preconditioning.

Patients and Methods

The patients were divided into five groups, each group including of 20 patients. The precondition was applied as 1, 5, 10 and 15 min in Groups I, II, III and IV and Group V was the control group. Repeated blood samples were taken to measure the total antioxidant status (TAS), total oxidant status and oxidative stress index (OSI) values, just before insufflation, at the end of the operation and at 6 and 24 h of the post-operative period.

Results

A significant difference was observed between the TAS values at the end of the operation and at the sixth post-operative time of the four groups (P = 0.001, 0.000, 0.001, 0.019 and 0.033, respectively). Furthermore, a significant difference was observed between TAS values at the post-operative 24th h of Group III and Group V, and also a significant difference was observed between the OSI values at the post-operative 6th h of Groups III and V.

Conclusion

The low OSI and TAS values may interpret as a low degree of oxidative damage. The OSI values at the post-operative 6 h of Groups I and II were lower than those of other groups. We accept this result as low oxidative damage.

Effect of laparoscopic liver resection versus the open technique on hepatocyte regenerating activity in the rat

BACKGROUND

Laparoscopic liver resection offers a safe and feasible option primarily for the excision of hepatic neoplasms. Timely recovery of liver volume is a key factor for improving prognosis and post-operative mortality of patients undergone liver resection. The aim of the present study was to compare liver regeneration after laparoscopic over open partial hepatectomy.

METHODS

Wistar rats were subjected to laparoscopic 70% hepatectomy (group LAP-HEP), open 70% hepatectomy (group HEP), sham operation (group Sham) or no intervention (group Control). At various timepoints following operation (1 h-2 weeks), the liver was excised to assess relative liver weight, thiobarbituric acid reactive substances (TBARS) levels, mitotic activity, tissue expression of Nuclear Factor-κB (NFκB), Intercellular Adhesion Molecule-1 (ICAM-1) and Vascular Cell Adhesion Molecule-1 (VCAM-1) and the histopathologic profile.

RESULTS

No differences were seen in relative liver weight between hepatectomy groups. Mitotic index was increased in all operative study groups, being higher in group LAP-HEP than in group HEP. TBARS levels were higher in group LAP-HEP compared to group HEP. NFκB and VCAM-1 tissue expression scores were increased in all operative study groups with VCAM-1 being higher in group HEP, while ICAM-1 was overexpressed only in hepatectomy groups. Mild histopathologic lesions were noted in hepatectomy groups with the histopathologic score being higher in group HEP (24 h).

CONCLUSIONS

Laparoscopic liver resection enhanced hepatocyte mitotic activity which was accompanied by mild oxidative stress and a less pronounced local inflammatory response and tissue injury to that of the open technique.

Transperitoneal versus extraperitoneal robot-assisted laparoscopic radical prostatectomy on postoperative hepatic and renal function

Background

In this retrospective study, we evaluated the effect of two approaches of robotic-assisted laparoscopic radical prostatectomy (RALP). The first approach was pneumoperitoneum via transperitoneal (TP-RALP), and the second approach was extraperitoneal (EP-RALP) on visceral function. We aimed to provide clinical evidence for the perioperative safety with RALP and to help the surgical team choose an appropriate approach for those with hepatic or renal insufficiency.

Methods

One hundred and fifty-seven eligible prostate cancer patients from 2015 to 2019 were included in this study. The postoperative related laboratory tests were compared between transperitoneal and extraperitoneal. The primary endpoint was hepatic and renal function. We also evaluate the intraoperative amount of bleeding, the length of postoperative hospital stays, the occurrence of postoperative complications (lymphatic leakage, bleeding, and infection), and the prostate-specific antigen (PSA).

Results

Postoperative total bilirubin and bound bilirubin in both groups were significantly increased, while total protein, albumin, globulin, urea, and uric acid were significantly decreased (P<0.05). The total protein, albumin, and globulin are significantly higher in the EP-RALP group than in the TP-RALP group (P<0.05) postoperatively. There are no statistical differences in estimated glomerular filtration rate (eGFR) and creatinine clearance (CCR) between these two groups, postoperatively.

Conclusions

RALP had a significant effect on hepatic function after both TP-RALP and EP-RALP approaches, while the latter showed a lesser extent. Our results suggested that pneumoperitoneal pathways have significant effects on protein consumption. Thus, we should require a more cautious choice of surgical approaches when it comes to patients with impaired hepatic function or under risk of hepatic malfunction.

Comparison of postoperative liver function between different dissection techniques during laparoscopic cholecystectomy

Aim:

In this study, we investigated and compared the effect of different types of dissector (Maryland vs Hook) on changes in liver function tests (LFTs) after laparoscopic cholecystectomy.

Patients & methods:

The enrolled patients were divided into two groups. Group A patients underwent dissection by Maryland dissecting forceps, group B by Hook dissecting instrument. LFTs were measured preoperatively and at 1 day and 1 week, postoperatively.

Results:

For both Maryland and Hook dissection, the 1-day postoperative values for total bilirubin, alanine aminotransferase and aspartate aminotransferase were significantly higher than the preoperative values. Also, there were no statistical differences between Hook and Maryland.

Conclusion:

The elevation of LFTs seems to be attributed to other factors.

Laparoscopic cholecystectomy (LC) is an alternative to laparotomy and has become the standard treatment of benign gallbladder diseases. However, it has been noted that (following LC) the serum level of certain liver function tests (LFT) raises markedly in patients who had preoperatively normal LFT. Pneumoperitoneum is the main contributing factor. This is the first study to evaluate the effect of different dissectors on alteration of LFTs after LC. As there were no statistical differences in the variation of LFTs between the Maryland and Hook, it seems that the dissector type has no effect on the alteration of LFTs.

Glucocorticoid use and ischemia-reperfusion injury in laparoscopic liver resection: Randomized controlled trial

AIM

Laparoscopic liver resection (LLR) is increasingly carried out worldwide. However, there are concerns regarding ischemia-reperfusion injury caused by pneumoperitoneum and the Pringle maneuver. It is not clear whether perioperative use of glucocorticoids lowers the risk of ischemia-reperfusion hepatic injury in LLR as has been reported for open liver resection. The aim of the present study was to investigate the role of perioperative glucocorticoid use in improving hepatic function and surgical outcomes after LLR.

METHODS

In this double-blind, randomized controlled trial (UMIN000013823), we enrolled 130 patients who presented to our institution for LLR between April 2014 and October 2018. Six patients were excluded, resulting in 124 patients being randomized to either the glucocorticoid or the control group. Preoperatively, patients in the glucocorticoid group received 500 mg methylprednisolone in saline solution, patients in the control group saline solution only. Surgical outcomes and blood parameters were compared between the two groups.

RESULTS

The Pringle maneuver could not be carried out in 24 patients, resulting in 50 patients in each group being included in the analysis. Postoperatively, total, direct and indirect bilirubin, and C-reactive protein and interleukin-6 levels were significantly lower, albumin levels were significantly higher, and prothrombin time was significantly shorter in the glucocorticoid than in the control group. Surgical outcomes were not significantly different between the groups.

CONCLUSION

This first report on preoperative glucocorticoid use in LLR showed that it significantly improved postoperative liver function and thus might enhance the safety of LLR.

High-pressure carbon dioxide pneumoperitoneum induces oxidative stress and mitochondria-associated apoptotic pathway in rabbit kidneys with severe hydronephrosis

The primary aim of the present study was to investigate the potential effect of high‑pressure carbon dioxide (CO2) pneumoperitoneum on kidneys with severe hydronephrosis and to investigate the possible underlying mechanism. A total of 18 rabbits underwent a surgical procedure inducing severe hydronephrosis. Rabbits were then divided at random into three groups (n=6 each) and subjected to intraabdominal pressure of 0, 8 or 18 mmHg, respectively. CO2 inflation lasted for 90 min in the pneumoperitoneum groups. Oxidative stress was assessed by measurements of reactive oxygen species (ROS). Activation of apoptosis was analyzed by western blot analysis of B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated x protein (Bax), cytochrome c (Cyt c), caspase‑3 and caspase‑9 levels. In addition, TUNEL assay, hematoxylin and eosin (H&E) staining, measurement of mitochondrial membrane potential (MMP) and detection of changes to kidney ultramicrostructure were performed. In the 0 and 8 mmHg groups, all results were normal and similar. However, in the 18 mmHg group, the kidneys suffered oxidative damage and mitochondrial injuries, and increased ROS levels, lower MMP and mitochondrial vacuolization were observed. Furthermore, the mitochondrial/caspase‑dependent pathway of apoptosis was activated, as indicated by the apoptotic index, and the expression levels and translocation of Bax, Bcl‑2, Cyt c, caspase‑3 and caspase‑9. Therefore, it is concluded that high‑pressure CO2 pneumoperitoneum induces oxidative damage and apoptosis in rabbit kidneys with severe hydronephrosis, which is associated with the mitochondrial apoptotic pathway.

Arterioportal shunting, splanchnic capillary perfusion, and the effects of colloids during capnoperitoneum in neonatal and adolescent pigs

BACKGROUND

Clinical and experimental data indicate that neonates are sensitive to the CO₂ pneumoperitoneum. An impaired splanchnic perfusion during laparoscopy in adults has been reported. We recently confirmed that intravenous colloids improve macrocirculatory function in neonates. We aimed to determine the impact of CO₂ pneumoperitoneum on the perfusion of splanchnic organs in the young including effects of colloid application.

METHODS

Male piglets (n = 25) were divided into four groups: (1) neonatal controls, (2) neonates with crystalloid restitution, (3) neonates with colloidal restitution, and (4) adolescents with crystalloid restitution. Animals were ventilated and subjected to a 3-h, 10 mmHg CO₂ pneumoperitoneum followed by 2 h resuscitation. Hepatic, splanchnic, and arteriovenous shunt perfusion was assessed via central and portal venous catheters. Capillary organ flow was detected by fluorescent microspheres. The rate of bile flow was measured.

RESULTS

The neonatal crystalloid group showed a significant decrease in the intestinal capillary perfusion at the end of the recovery period. This was not detectable in the adolescent and colloid group. There was a significant increase in microcirculatory arterioportal shunt flow during the CO₂ pneumoperitoneum in both neonatal groups but not in the sham and adolescent groups (p < 0.05). Hepatic arterial perfusion increased after insufflation in all groups and dropped during capnoperitoneum to levels of about 70% baseline. There was no significant impairment of splanchnic perfusion or bile flow as a result of the pneumoperitoneum in all groups.

CONCLUSIONS

Capillary perfusion of the abdominal organs was stable during capnoperitoneum and recovery in adolescents and neonates with colloid restitution, but not with crystalloid restitution. Significant arterioportal shunting during capnoperitoneum could affect hepatic microcirculation in neonates. Our data confirm that moderate pressure capnoperitoneum has no major effect on the perfusion of abdominal organs in neonates with adequate substitution.

Effect of Increased Intra-abdominal Pressure on Liver Histology and Hemodynamics: An Experimental Study

BACKGROUND

While reduction of portal venous (PV) blood flow has been described in animal models of intra-abdominal hypertension, reports on compensatory changes in hepatic arterial (HA) flow, known as the hepatic arterial buffer response are controversial.

MATERIALS AND METHODS

Pneumoperitoneum with helium was induced in 13 piglets. Hemodynamic measurements and pathological assessment were conducted at baseline and during the three subsequent phases: Phase A: 45 minutes with a stable intra-abdominal pressure of 25 mmHg; phase B: 45 minutes with a stable intra-abdominal pressure of 40 mmHg; and phase C during which the abdomen was re-explored and reperfusion of the liver was allowed to take place.

RESULTS

Phase B pressure was significantly greater than phase A pressure in both the PV and the inferior vena cava, demonstrating a positive association between escalating intra-abdominal hypertension and the pressure in these two vessels (all p<0.001). In contrast, HA pressure was comparable between baseline and phase A, while it tended to decrease in phase B. Regarding histology, the most notable abnormality was the presence of inflammatory infiltrates and hepatocyte necrosis.

CONCLUSION

Helium-insufflation increased PV pressure with a partial compensatory decrease of HA pressure. Nonetheless, findings consistent with hepatic ischemia were observed on pathology.

Changes in duration of action of rocuronium following decrease in hepatic blood flow during pneumoperitoneum for laparoscopic gynaecological surgery

Background

A moderate insufflation pressure and deep neuromuscular blockade (NMB) have been recommended in laparoscopic surgery in consideration of the possible reduction in splanchnic perfusion due to the CO₂-pneumoperitoneum. Since the liver is the major organ for rocuronium metabolism, the question of whether NMB of rocuronium would change with the variation of liver perfusion during pneumoperitoneum during laparoscopic surgery merits investigation.

Methods

In this prospective study, a total of sixty female patients scheduled for either selective laparoscopic gynaecological surgery (group laparoscopy) or laparotomy for gynaecological surgery (group control) were analyzed. Rocuronium was administered with closed-loop feedback infusion system, which was also applied to monitor NMB complied with good clinical research practice (GCRP). The onset time, clinical duration, and recovery index were measured. Hepatic blood flow was assessed by laparoscopic intraoperative ultrasonography before insufflation/after entering the abdominal cavity (T1), 5 min after insufflation in the Trendelenburg position/5 min after skin incision (T2), 15 min after insufflation in the Trendelenburg position/15 min after skin incision (T3), 30 min after insufflation in the Trendelenburg position/30 min after skin incision (T4), and 5 min after deflation/before closing the abdomen (T5) in group laparoscopy/group control respectively. The relationship between the clinical duration of rocuronium and portal venous blood flow was analyzed using linear or quadratic regression.

Result

The clinical duration and RI of rocuronium were both prolonged significantly in group laparoscopy (36.8 ± 8.3 min; 12.8 ± 5.5 min) compared to group control (29.0 ± 5.8 min; 9.8 ± 4.0 min) (P < 0.0001; P = 0.018). A significant decrease was found in portal venous blood flow during the entire pneumoperitoneum period in group laparoscopy compared with group control (P < 0.0001). There was a significant correlation between the clinical duration of rocuronium and portal venous blood flow (Y = 51.800-0.043X + (1.86E-005) X²; r² = 0.491; P < 0.0001).

Conclusion

Rocuronium-induced NMB during laparoscopic gynaecological surgery might be prolonged due to the decrease in portal venous blood flow induced by CO₂-pneumoperitoneum. Less rocuronium could be required to achieve a desirable NMB in laparoscopic gynaecological surgery.

Trial registration

ChiCTR. Registry number: ChiCTR-OPN-15007524. Date of registration: December 4, 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0335-1) contains supplementary material, which is available to authorized users.

First totally laparoscopic ALPPS procedure with selective hepatic artery clamping: Case report of a new technique

BACKGROUND

ALPPS (Associating Liver Partition and Portal vein ligation for Staged hepatectomy) is a new surgical approach for the treatment of liver tumors. It is indicated in cases where the future liver remnant is not sufficient to maintain postoperative liver function. We report a totally laparoscopic ALPPS with selective hepatic artery clamping. Pneumoperitoneum itself results in up to 53% of portal vein flow and selective hepatic artery clamping can reduce blood loss while maintaining hepatocellular function. Therefore, the combination of both techniques may result in effective control of bleeding with no damage in the liver function that may have direct impact in the result of ALPPS procedure.

METHODS

A 65-year-old man with colorectal liver metastases in all liver segments, except liver segment 1 (S1), were evaluated as unresectable. He underwent chemotherapy with objective response and multidisciplinary board decided for ALPPS procedure. First stage was performed entirely by laparoscopy and consisted of enucleation of metastases from segments 2 and 3, ligation of the right portal vein and liver splitting under selective common hepatic artery clamping. The second stage was done 3 weeks later and consisted of laparoscopic right trisectionectomy by laparoscopy.

RESULTS

Operative time was 250 and 200 minutes, respectively. Estimated blood loss was 150 and 100 mL. There was no need for transfusion or hospitalization in intensive care. He was discharged on the 3rd and 5th postoperative day, respectively. Recovery was uneventful after both stages and patient did not present any sign of liver failure. Elevation of liver enzymes was minimal. Computerized tomography (CT) scan before second stage showed a liver hypertrophy of 53%, sFLR was 0.37 before second stage, or 33% of the total liver volume. CT scan shows no residual liver disease and optimum liver regeneration. Patient is well with no evidence of the disease 11 months after the procedure.

CONCLUSIONS

Totally laparoscopic ALPPS is a feasible and safe approach for selected patients with liver tumors. The hypertrophy of the remaining liver was adequate and sequential procedures were performed without morbidity and no mortality. Selective hepatic artery clamping seems to be an interesting solution to decrease intraoperative blood loss without the harsh effect of Pringle maneuver.

Use of Caval Subtraction 2D Phase-Contrast MR Imaging to Measure Total Liver and Hepatic Arterial Blood Flow: Preclinical Validation and Initial Clinical Translation

Caval subtraction phase-contrast MR imaging is technically feasible and may offer a reproducible and clinically viable method for measuring total liver blood flow and hepatic arterial flow.

Purpose

To validate caval subtraction two-dimensional (2D) phase-contrast magnetic resonance (MR) imaging measurements of total liver blood flow (TLBF) and hepatic arterial fraction in an animal model and evaluate consistency and reproducibility in humans.

Materials and Methods

Approval from the institutional ethical committee for animal care and research ethics was obtained. Fifteen Sprague-Dawley rats underwent 2D phase-contrast MR imaging of the portal vein (PV) and infrahepatic and suprahepatic inferior vena cava (IVC). TLBF and hepatic arterial flow were estimated by subtracting infrahepatic from suprahepatic IVC flow and PV flow from estimated TLBF, respectively. Direct PV transit-time ultrasonography (US) and fluorescent microsphere measurements of hepatic arterial fraction were the standards of reference. Thereafter, consistency of caval subtraction phase-contrast MR imaging–derived TLBF and hepatic arterial flow was assessed in 13 volunteers (mean age, 28.3 years ± 1.4) against directly measured phase-contrast MR imaging PV and proper hepatic arterial inflow; reproducibility was measured after 7 days. Bland-Altman analysis of agreement and coefficient of variation comparisons were undertaken.

Results

There was good agreement between PV flow measured with phase-contrast MR imaging and that measured with transit-time US (mean difference, −3.5 mL/min/100 g; 95% limits of agreement [LOA], ±61.3 mL/min/100 g). Hepatic arterial fraction obtained with caval subtraction agreed well with those with fluorescent microspheres (mean difference, 4.2%; 95% LOA, ±20.5%). Good consistency was demonstrated between TLBF in humans measured with caval subtraction and direct inflow phase-contrast MR imaging (mean difference, −1.3 mL/min/100 g; 95% LOA, ±23.1 mL/min/100 g). TLBF reproducibility at 7 days was similar between the two methods (95% LOA, ±31.6 mL/min/100 g vs ±29.6 mL/min/100 g).

Conclusion

Caval subtraction phase-contrast MR imaging is a simple and clinically viable method for measuring TLBF and hepatic arterial flow.

Online supplemental material is available for this article.

Protective effect of theophylline on renal functions in experimental pneumoperitoneum model

Our objective in this experimental study is to research the effect of the intra-abdominal pressure which rises following pneumoperitoneum and whether Theophylline has a possible protective activity on this situation. In our study, 24 Wistar Albino rats were used. Rats were divided into two groups. The first group was set for only pneumoperitoneum model. The second group was given 15 mg/kg of Theophylline intraperitoneally before setting pneumoperitoneum model. Then urea, creatinine, cystatin-C, tissue and serum total antioxidant capacity, total oxidant capacity and oxidative stress index in two groups were measured and compared with each other. Apoptosis and histopathological conditions in the renal tissues were examined. The differences between the groups were analyzed with the Mann-Whitney U test. Results were considered significant at p < 0.05. No statistically significant difference was determined between tissue and serum averages in two groups in terms of TAS, TOS and OSI values (p > 0.05). The mean value of urea were similar in pneumoperitoneum and pneumoperitoneum + theophylline groups (p = 0.12). The mean cystatin-C value was 2.2 ± 0.3 µg/mL in pneumoperitoneum, 1.74 ± 0.33 µg/mL in pneumoperitoneum + theophylline (p = 0.002). According to our study, lower cystatin-C levels in the group, where Theophylline was given, are suggestive of lower renal injury in this group. However, this opinion is interrogated as there is no difference in terms of tissue and serum TAS, TOS, OSI and urea values between the groups.

Hepatic arterial vasodilation is independent of portal hypertension in early stages of cirrhosis

Introduction

The compensatory increase in hepatic arterial flow with a decrease in portal venous flow is known as the hepatic arterial buffer response. In cirrhosis with elevated portal pressure, the vascular resistance of the hepatic artery is decreased. Whether this lower resistance of the hepatic artery is a consequence of portal hypertension or not remains unknown.

Study Aim

The aim of the study was to investigate the hepatic arterial resistance and response to vasoconstriction in cirrhosis without portal hypertension (normal portal resistance).

Methods

Cirrhosis was induced by CCl₄-inhalation for 8 weeks (8W, normal portal resistance) and for 12–14 weeks (12W, elevated portal resistance). Bivascular liver perfusion was performed at 8W or 12W and dose response curves of methoxamine were obtained in the presence or absence of LNMMA (nitric oxide synthase blocker). Vascular resistances of the hepatic artery (HAR), portal vein (PVR) and sinusoids (SVR) were measured. Western Blot (WB) and Immunohistochemistry (IHC) were done to measure eNOS and HIF 1a expression.

Results

HAR in both groups of cirrhotic animals (8W and 12W) were lower compared to controls. Dose response curves to methoxamine revealed lower HAR in both cirrhotic models (8W and 12W) regardless the magnitude of portal resistance. LNMMA corrected the dose response curves in cirrhosis (8W and 12W) to control. WB and IHC show increased protein expression of eNOS and HIF1a in 8W and 12W.

Conclusion

Hepatic arterial resistance is decreased in cirrhosis independent of portal resistance. Vasodilation of the hepatic artery in cirrhosis seems to be influenced by hypoxia rather than increase in portal resistance. Nitric oxide is the main vasodilator.

Does pneumoperitoneum adversely affect growth, development and liver function in biliary atresia patients after laparoscopic portoenterostomy?

PURPOSE

We assessed the effect of high partial pressure of arterial carbon dioxide (PaCO2) due to pneumoperitoneum (PP) on growth (height/weight) and development (gross/fine motor function, receptive/expressive communication, and social interaction), by comparing outcome after portoenterostomy (PE) for biliary atresia (BA) using laparoscopic PE (LPE: n = 13) and open PE (OPE: n = 13) cases performed between 2005 and 2014.

METHODS

Our PE is based on Kasai's original PE. All data were collated prospectively.

RESULTS

Differences in duration of follow-up (LPE: 38.8 months; OPE: 38.1 months), jaundice clearance (LPE: 12/13 = 92.3 %; OPE: 9/13 = 69.2 %), survival with the native liver (LPE: 10/13 = 76.9 %; OPE: 9/13 = 69.2 %), incidence of cholangitis, hypersplenism, and incidence of esophageal varices were not significant. Mean intraoperative PaCO2 was significantly higher in LPE (LPE: 50.1 mmHg; OPE: 40.7 mmHg, p < 0.05). Liver function impairment was not statistically different, although LPE results were slightly worse. There was no overall delay in growth observed, although height/weight gain was more consistent in LPE. The pattern of developmental delay observed was similar for LPE and OPE suggesting that developmental delay is not PE-related; in other words, PP is not implicated in developmental delay.

CONCLUSIONS

PP during LPE would appear to have no adverse effects on overall growth/development and liver function in BA patients.

Effect of laparoscopic abdominal surgery on splanchnic circulation: Historical developments

With the developments in medical technology and increased surgical experience, advanced laparoscopic surgical procedures are performed successfully. Laparoscopic abdominal surgery is one of the best examples of advanced laparoscopic surgery (LS). Today, laparoscopic abdominal surgery in general surgery clinics is the basis of all abdominal surgical interventions. Laparoscopic abdominal surgery is associated with systemic and splanchnic hemodynamic alterations. Inadequate splanchnic perfusion in critically ill patients is associated with increased morbidity and mortality. The underlying pathophysiological mechanisms are still not well understood. With experience and with an increase in the number and diversity of the resulting data, the pathophysiology of laparoscopic abdominal surgery is now better understood. The normal physiology and pathophysiology of local and systemic effects of laparoscopic abdominal surgery is extremely important for safe and effective LS. Future research projects should focus on the interplay between the physiological regulatory mechanisms in the splanchnic circulation (SC), organs, and diseases. In this review, we discuss the effects of laparoscopic abdominal surgery on the SC.

Association between duration of carbon dioxide pneumoperitoneum during laparoscopic abdominal surgery and hepatic injury: a meta-analysis

BACKGROUND

The aim of this study is to accurately assess whether the duration of intraoperative carbon dioxide pneumoperitoneum (CDP) is associated with the induction of hepatic injury.

METHODS

We conducted a systematic review of PubMed, Embase, and Cochrane Library databases (through February 2014) to identify case-match studies that compared high-pressure CDP with low-pressure CDP or varied the duration of CDP in patients who underwent abdominal surgery. The outcome of interest was postoperative liver function (ALT, AST, TB).

RESULTS

Eleven comparative studies involving 2,235 participants were included. Overall, levels of ALT, AST, and TB (on postoperative days 1, 3, and 7) were significantly elevated in the study groups. However, the results of the subanalyses of those who underwent laparoscopic colorectal cancer resection (LCR) versus open colorectal cancer resection (OCR) and those who underwent laparoscopic gastric bypass (LGBP) versus open gastric bypass (OGBP) were inconsistent.

CONCLUSIONS

The current evidence suggests that the duration of CDP during laparoscopic abdominal surgery may be associated with hepatic injury. Additional large-scale, randomized, controlled trials are urgently needed to further confirm this.

Effects of different pressure levels of CO2 pneumoperitoneum on liver regeneration after liver resection in a rat model

BACKGROUND

A recent study demonstrated that high pressure of carbon dioxide (CO2) pneumoperitoneum before liver resection impairs postoperative liver regeneration. This study was aimed to investigate effects of varying insufflation pressures of CO2 pneumoperitoneum on liver regeneration using a rat model.

METHODS

180 male Wistar rats were randomly divided into three groups: control group (without preoperative pneumoperitoneum), low-pressure group (with preoperative pneumoperitoneum at 5 mmHg), and high-pressure group (with preoperative pneumoperitoneum at 10 mmHg). After pneumoperitoneum, all rats were subjected to 70% partial hepatic resection and then euthanized at 0 min, 12 h, and on postoperative days (PODs) 1, 2, 4, and 7. Following outcome parameters were used: liver regeneration (liver regeneration rate, mitotic count, Ki-67 labeling index), hepatocellular damage (serum aminotransferases), oxidative stress [serum malondialdehyde (MDA)], interleukin-6 (IL-6), and hepatocyte growth factor (HGF) expression in the liver tissue.

RESULTS

No significant differences were observed for all parameters between control and low-pressure groups. The liver regeneration rate and mitotic count were significantly decreased in the high-pressure group than in control and low-pressure groups on PODs 2 and 4. Postoperative hepatocellular damage was significantly greater in the high-pressure group on PODs 1, 2, 4, and 7 compared with control and/or low-pressure groups. Serum MDA levels were significantly higher in the high-pressure group on PODs 1 and 2, and serum IL-6 levels were significantly higher in the high-pressure group at 12 h and on POD 1, compared with control and/or low-pressure groups. The HGF tissue expression was significantly lower in the high-pressure group at 12 h and on PODs 1 and 4, compared with that in control and/or low-pressure groups.

CONCLUSIONS

High-pressure pneumoperitoneum before 70% liver resection impairs postoperative liver regeneration, but low-pressure pneumoperitoneum has no adverse effects. This study suggests that following laparoscopic liver resection using appropriate pneumoperitoneum pressure, no impairment of liver regeneration occurs.

Effects of carbon dioxide pneumoperitoneum on hepatic and renal morphology of rats after segmental colectomy and colonic anastomosis

PURPOSE

To evaluate the effects of increased intraperitoneal pressure caused by carbon dioxide pneumoperitoneum on the hepatic and renal morphology of rats.

METHODS

Fifty-four adult male rats were randomly divided into three groups (P, PP and C) after anesthesia: P - in 18 animals, pneumoperitoneum was established for 30 minutes immediately before laparotomy; PP - in 18 animals, pneumoperitoneum was established for 60 minutes divided into 30 immediately before laparotomy and 30 after abdominal closure; control group (C) - 18 animals underwent laparotomy without pneumoperitoneum induction. The pneumoperitoneum was maintained at a pressure of 5 mm Hg. Nine animals in each group were killed on the 3(rd) and 7(th) postoperative days, when kidney and liver samples were collected for morphological analysis. The liver specimens were stained with hematoxylin and eosin (HE), and the kidney specimens, with HE and von Kossa. Blinded examiners analyzed the slides.

RESULTS

No changes in renal morphology were found. Liver samples showed histological signs of degeneration in animals in the pneumoperitoneum groups killed on the 7(th) postoperative day (p=0.029).

CONCLUSION

The CO(2) pneumoperitoneum did not affect renal morphology but caused hydropic degeneration in the liver of animals killed on the 7(th) postoperative day.

Two clinically relevant pressures of carbon dioxide pneumoperitoneum cause hepatic injury in a rabbit model

AIM: To observe the hepatic injury induced by carbon dioxide pneumoperitoneum (CDP) in rabbits, compare the effects of low- and high-pressure pneumoperitoneum, and to determine the degree of hepatic injury induced by these two clinically relevant CDP pressures.

METHODS: Thirty healthy male New Zealand rabbits weighing 3.0 to 3.5 kg were randomly divided into three groups (n = 10 for each group) and subjected to the following to CDP pressures: no gas control, 10 mmHg, or 15 mmHg. Histological changes in liver tissues were observed with hematoxylin and eosin staining and transmission electron microscopy. Liver function was evaluated using an automatic biochemical analyzer. Adenine nucleotide translocator (ANT) activity in liver tissue was detected with the atractyloside-inhibitor stop technique. Bax and Bcl-2 expression levels were detected by western blotting.

RESULTS: Liver functions in the 10 mmHg and 15 mmHg experimental groups were significantly disturbed compared with the control group. After CDP, the levels of alanine transaminase and aspartate transaminase were 77.3 ± 14.5 IU/L and 60.1 ± 11.4 IU/L, respectively, in the 10 mmHg experimental group and 165.1 ± 19.4 IU/L and 103.8 ± 12.3 IU/L, respectively, in the 15 mmHg experimental group, which were all higher than those of the control group (P < 0.05). There was no difference in pre-albumin concentration between the 10 mmHg experimental group and the control group, but the pre-albumin level of the 15 mmHg experimental group was significantly lower than that of the control group (P < 0.05). No significant differences were observed in the levels of total bilirubin or albumin among the three groups. After 30 and 60 min of CDP, pH was reduced (P < 0.05) and PaCO₂ was elevated (P < 0.05) in the 10 mmHg group compared with controls, and these changes were more pronounced in the 15 mmHg group. Hematoxylin and eosin staining showed no significant change in liver morphology, except for mild hyperemia in the two experimental groups. Transmission electron microscopy showed mild mitochondrial swelling in hepatocytes of the 10 mmHg group, and this was more pronounced in the 15 mmHg group. No significant difference in ANT levels was found between the control and 10 mmHg groups. However, ANT concentration was significantly lower in the 15 mmHg group compared with the control group. The expression of hepatic Bax was significantly increased in the two experimental groups compared with the controls, but there were no differences in Bcl-2 levels among the three groups. Twelve hours after CDP induction, the expression of hepatic Bax was more significant in the 15 mmHg group than in the 10 mmHg group.

CONCLUSION: A CDP pressure of 15 mmHg caused more substantial hepatic injury, such as increased levels of acidosis, mitochondrial damage, and apoptosis; therefore, 10 mmHg CDP is preferable for laparoscopic operations.

A protective technique for retraction of the liver during laparoscopic gastrectomy for gastric adenocarcinoma: using a Penrose drain

BACKGROUND

Retraction of the liver is necessary to ensure an adequate working space in laparoscopic surgery, but the retraction force applied may cause transient liver dysfunction. We have introduced the technique using a Penrose drain to suspend the liver with the performance of laparoscopic gastrectomy for gastric adenocarcinoma.

METHODS

111 patients with gastric adenocarcinoma underwent laparoscopic gastrectomy using either a Penrose drain (n = 47) or a Nathanson's retractor (n = 64) for displacement of the liver. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, alkaline phosphatase (ALP) and albumin were compared among the groups at baseline, immediately after operation, and on postoperative days (POD) 1, 2, 3, 5, and 7.

RESULTS

The levels of ALT on POD 2, 3, and 5 were significant higher in the Nathanson's retractor group than in the Penrose drain group. Levels of AST on POD 2 and 3 were also higher in the Nathanson's retractor group than in the Penrose drain group. There was no significant difference in total bilirubin, ALP, and serum albumin levels between groups.

CONCLUSIONS

The use of the Penrose drain for retraction of the liver appears to attenuate postoperative liver dysfunction during laparoscopic gastrectomy for gastric adenocarcinoma.

Regulation of hepatic blood flow: The hepatic arterial buffer response revisited

The interest in the liver dates back to ancient times when it was considered to be the seat of life processes. The liver is indeed essential to life, not only due to its complex functions in biosynthesis, metabolism and clearance, but also its dramatic role as the blood volume reservoir. Among parenchymal organs, blood flow to the liver is unique due to the dual supply from the portal vein and the hepatic artery. Knowledge of the mutual communication of both the hepatic artery and the portal vein is essential to understand hepatic physiology and pathophysiology. To distinguish the individual importance of each of these inflows in normal and abnormal states is still a challenging task and the subject of ongoing research. A central mechanism that controls and allows constancy of hepatic blood flow is the hepatic arterial buffer response. The current paper reviews the relevance of this intimate hepatic blood flow regulatory system in health and disease. We exclusively focus on the endogenous interrelationship between the hepatic arterial and portal venous inflow circuits in liver resection and transplantation, as well as inflammatory and chronic liver diseases. We do not consider the hepatic microvascular anatomy, as this has been the subject of another recent review.

Effect of increased abdominal pressure on cytokines (IL1 beta, IL6, TNFalpha), C-reactive protein (CRP), free radicals (NO, MDA), and histology

BACKGROUND

It is generally accepted that proinflammatory mediators, including cytokines, are responsible for the metabolic changes associated with injury. Recent clinical and experimental studies have also shown that the laparoscopic procedures actually produce ischemia-reperfusion injury in the organs by oxygen-derived free radicals. This study aimed to assess the effect of different insufflation pressures and laparotomy on tissue response by comparing the proinflammatory cytokines, C-reactive protein, and serum and tissue levels of oxygen-derived free radicals.

METHODS

Forty mature New Zealand white rabbits were assigned to 4 groups of 10 animals. In groups 1 to 3, CO2 pneumoperitoneum was created using an automatic insufflator to the designated pressure of 10, 15, and 20 mm Hg, respectively. The remaining 10 animals underwent laparotomy using 10 cm midline incision (group 4). Blood samples were collected before (0 min) and at the end of the procedure (60 min). After the collection of last blood samples, all animals were killed and samples from liver and gut were obtained for measurements of tissue malondialdehyde levels and histology.

RESULTS

The proinflammatory cytokine levels were increased significantly in groups 1 to 3, but did not change in the laparotomy group. Serum C-reactive protein levels were elevated in all groups. The comparison of the results between the laparotomy and laparoscopy groups showed that serum interleukin 6 and nitric oxide levels were significantly elevated in relation the intra-abdominal pressure, and serum interleukin 6 and nitric oxide levels peaked in group 3. Tissue malondialdehyde levels were significantly higher in groups 1 and 2 than in groups 3 and 4.

CONCLUSIONS

The findings of our experiment suggest that the elevated intra-abdominal pressure is responsible for ischemia, free radical production, and proinflammatory cytokine response-mediated cell damage during laparoscopic surgery.

Increased susceptibility to liver damage from pneumoperitoneum in a murine model of biliary atresia

HYPOTHESIS

We hypothesized that livers with biliary atresia (BA) are more susceptible to the harmful effects of a high-pressure CO(2) pneumoperitoneum (PP) than healthy livers.

METHODS

A murine model of BA was used in this experiment. Mice were divided into 6 groups: (1) control Balb/c; (2) control Balb/c, CO(2)-PP; (3) control BA; (4) BA-sham; (5) BA, CO(2)-PP; and (6) BA, air-PP. Mice from groups 2, 5, and 6 underwent an 8-mm Hg-PP for 60 minutes. Liver samples were collected for histology, colorimetry, and flow cytometry analysis 18 to 24 hours after the procedure. Markers of apoptosis were investigated as indicators of acute cell damage.

RESULTS

We observed a statistically significant higher rate of apoptosis in livers with BA exposed to a prolonged CO(2)-PP or air-PP compared with control groups. There were no significant differences between groups 1 and 2, or between groups 5 and 6.

CONCLUSIONS

In this animal model, we have shown that livers with BA are more susceptible than healthy livers to injury by a prolonged PP. This injury was caused by both CO(2) and air-PP, implying that it is the direct result of pressure. These results may have implications for the success of minimally invasive Kasai procedures.

Modification of the hepatic hemodynamic response to acute changes in PaCO2 by nitric oxide synthase inhibition in rabbits

BACKGROUND

Hypercapnia has been reported to modify liver circulation. The vascular regulations implicated in this response remain partly unknown.

METHODS

Using anesthetized and ventilated rabbits, we designed this study to evaluate the hepatic artery and portal vein blood flow velocity adjustments (20 MHz pulsed Doppler) after changes in PaCO2 (by varying the inspiratory fraction of CO2 and to assess the proper role of pH, independent of PaCO2 changes, the role of portal vein CO2, and the effect of nitric oxide synthase inhibition on CO2-induced modifications of hepatic hemodynamics.

RESULTS

Increasing PaCO2 from 30.9 +/- 5 mm Hg to 77 +/- 11 mm Hg increased arterial blood pressure by 20% (P < 0.01) and hepatic artery blood flow velocity by 90% (P < 0.05) and decreased aortic blood flow velocity by 15% and portal vein blood flow velocity by 40% (both P < 0.05). Changes in pH (1 mL of 0.1 N hydrochloric acid infusion) or isolated changes in portal vein CO2 at constant PaCO2 induced by CO2 insufflation in an open abdomen had no effect on hepatic hemodynamics. Pretreatment with a nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine (2.5 mg/kg), blunted the systemic response to hypercapnia, whereas the portal modifications persisted, with a largely attenuated hepatic artery blood flow increase.

CONCLUSIONS

CO2 per se acts on hepatic blood flow by its systemic effect, probably via chemoreflexes. Nitric oxide does not mediate hepatosplanchnic hemodynamic modifications to acute changes in PaCO2 but may play a permissive role by regulating the amplitude of hepatic vascular response.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

What should be the ideal time for ischemic preconditioning in a laparoscopic rat model?

BACKGROUND

Pneumoperitoneum (Pp) induces an ischemia and reperfusion (I/R) injury as a result of released oxidative stress markers. Ischemic preconditioning (IP) is one of the used methods to reduce the harmful effects of Pp, which is a mechanism for reducing organ I/R injury by a brief period of organ ischemia. The aim of this study was to investigate the ideal time for IP in the laparoscopic model.

METHODS

Thirty-two rats were assigned into four groups: group 1 (control, n = 8) was subjected to a sham operation. Group 2 (5-minutes IP, n = 8) was subjected to 5 minutes of Pp with 15 mm Hg of pressure followed immediately by 5 minutes of deflation, and after that, 60 minutes of Pp with 15 mm Hg, followed by 60 minutes of deflation. Group 3 (10-minutes IP, n = 8) was subjected to 10 minutes of Pp and 10 minutes of deflation. Group 4 (Pp only, n = 8) was subjected to 60 minutes of Pp with 15 mm Hg of pressure, followed by 60 minutes of deflation. At the end of the experiment, plasma malondialdehyde (MDA) values, the oxidative stress marker, and plasma-reduced glutathione (GSH) levels, the marker showing antioxidant activity, were determined.

RESULTS

Highest plasma MDA values were in group 4 (Pp only), followed by groups 2 and 3 and group 1 (P = 0.181). In addition, IP groups had almost the same values for MDA. Plasma GSH levels in the control group were significantly higher than those in the IP groups and the Pp-only group (P < 0.001). Similarly, as in MDA levels, no difference was found between plasma GSH levels of the IP 5-minutes and IP 10-minutes groups.

CONCLUSIONS

Five minutes of the IP model may be as reliable as 10 minutes of the IP model. In that case, 5 minutes of IP can be more suitable in reducing I/R injury in laparoscopy.

The impact of carbon dioxide pneumoperitoneum on liver regeneration after liver resection in a rat model

BACKGROUND

In recent years, laparoscopic hepatic resection is performed by an increasing number of surgeons. Despite many advantages of the laparoscopic procedure, it is unclear whether the pneumoperitoneum affects the postoperative liver regeneration after liver resection. The current study aimed to investigate the influence of a carbon dioxide (CO(2)) pneumoperitoneum on liver regeneration in a rat model.

METHODS

In this study, 60 male Wistar rats were subjected to 70% partial hepatic resection. Of these 60 animals, 30 underwent preoperative pneumoperitoneum at 9 mmHg for 60 min. After hepatic resection, the rats were killed at 12, 24, and 48 h, and on days 4 and 7. The outcome parameters were hepatocellular injury (plasma aminotransferases), oxidative stress (plasma malondialdehyde), interleukin-6 (IL-6), and liver regeneration (mitotic index, KI-67; regenerating liver mass).

RESULTS

The mitotic index was significantly lower in the pneumoperitoneum group than in the group without pneumoperitoneum at all time points (p < 0.05). In the pneumoperitoneum group, KI-67 was significantly lower on day 4 (p < 0.05). The liver regeneration rate was significantly lower for the animals with pneumoperitoneum on days 2 and 4 (p < 0.05). The postoperative hepatocellular injury was significantly greater after pneumoperitoneum at 12, 24, and 48 h (p < 0.05). Plasma malondialdehyde and IL-6 were significantly higher in the pneumoperitoneum group at 24 h and on day 4 (p < 0.05).

CONCLUSION

This study showed that pneumoperitoneum before extended liver resection impaired postoperative liver regeneration. Oxidative stress reaction and hepatocellular damage was markedly higher after pneumoperitoneum. Further investigations, especially with patients that have impaired liver function, are necessary for clinical consequences to be drawn from these results.

What is the role of the abdominal perfusion pressure for subclinical hepatic dysfunction in laparoscopic cholecystectomy?

BACKGROUND

Subclinical hepatic dysfunction after laparoscopic cholecystectomy (LC) has been described in the literature. However, this alteration is not encountered in all patients. In order to address this situation, a prospective study was conducted to investigate the effect of abdominal perfusion pressure (APP) on liver function tests after LC performed under constant intra-abdominal pressure (IAP).

PATIENTS AND METHODS

Of 78 patients who underwent LC between May 2007 and October 2007, 40 patients were eligible for the study. In all the patients, six parameters of liver function (aspartate aminotransferase, alanine aminotransferase, direct bilirubin, indirect bilirubin, alkaline phosphatase, and gamma-glutamyltransferase) were assessed before and 24 hours after surgery. Patients who showed more than a 100% increase in at least one parameter (group 1) were compared to those who did not (group 2) regarding age, sex, body weight, body height, operation time, pneumoperitoneum time, IAP, preoperative, and intraoperative APP.

RESULTS

Of the patients, 37.5% showed more than a 100% increase in at least one parameter of liver function. No significant difference was found between the two groups with regard to age, sex, body weight, body height, operation time, pneumoperitoneum time, and IAP. There were significant increase in AST and ALT at 24 hours postoperatively in group 1, as compared with group 2 (P = 0.000, P = 0.001). In comparison of preoperative APP with intraoperative APP values, group 1 showed a statistically significant decrease (P = 0.000), while no difference was found in group 2.

CONCLUSION

Subclinical hepatic dysfunction after LC could mostly be attributed to the negative effects of the pneumoperitoneum on hepatic blood flow. For the evaluation of hepatic hypoperfusion, APP may be a new criterion as a determinant of interaction with mean arterial pressure (MAP) and IAP.

Creatine synthesis: hepatic metabolism of guanidinoacetate and creatine in the rat in vitro and in vivo

Since creatinine excretion reflects a continuous loss of creatine and creatine phosphate, there is a need for creatine replacement, from the diet and/or by de novo synthesis. Creatine synthesis requires three amino acids, methionine, glycine, and arginine, and two enzymes, l-arginine:glycine amidinotransferase (AGAT), which produces guanidinoacetate acid (GAA), and guanidinoacetate methyltransferase (GAMT), which methylates GAA to produce creatine. In the rat, high activities of AGAT are found in the kidney, whereas high activities of GAMT occur in the liver. Rat hepatocytes readily convert GAA to creatine; this synthesis is stimulated by the addition of methionine, which increases cellular S-adenosylmethionine concentrations. These same hepatocytes are unable to produce creatine from methionine, arginine, and glycine. (15)N from (15)NH(4)Cl is readily incorporated into urea but not into creatine. Hepatic uptake of GAA is evident in vivo by livers of rats fed a creatine-free diet but not when rats were fed a creatine-supplemented diet. Rats fed the creatine-supplemented diet had greatly decreased renal AGAT activity and greatly decreased plasma [GAA] but no decrease in hepatic GAMT or in the capacity of hepatocytes to produce creatine from GAA. These studies indicate that hepatocytes are incapable of the entire synthesis of creatine but are capable of producing it from GAA. They also illustrate the interplay between the dietary provision of creatine and its de novo synthesis and point to the crucial role of renal AGAT expression in regulating creatine synthesis in the rat.

Nitric oxide administration restores the hepatic artery buffer response during porcine endotoxemia

The hepatic artery buffer response, which is lost during endotoxemia, plays a central role in the autoregulation of liver perfusion. A temporarily decreased synthesis of nitric oxide during early endotoxemia might be responsible for this dysfunction; hence exogenous administration of nitric oxide could reestablish the autoregulation of hepatic blood flow and help prevent hepatic damage later in septic shock. Fifteen pigs were treated with lipopolysaccharide +/- the nitric oxide donor nitroprusside-sodium via the portal vein. Hemodynamics were measured, and serum chemistry and liver biopsies for nitric oxide synthase expression were obtained. Lipopolysaccharide decreased arterial liver perfusion after 5 hours by 38% (p = .012), which was reversed by addition of nitroprusside (8%). Administration of nitroprusside preserved an increase of 28% in hepatic arterial upon portal vein flow reduction (p < .001). Nitroprusside maintained mRNA levels of constitutive nitric oxide synthase in liver tissue which were decreased by lipopolysaccharide (p = .026 vs. p = .114) and tempered the burst in inducible nitric oxide synthase expression at t = 3 hours. The early administration of the nitric oxide donor sodium nitroprusside during endotoxemia is able to reestablish the autoregulatory response of the hepatic artery following reduction of hepatic blood flow. This beneficial effect might help to prevent subsequent hepatic damage in the course of abdominal sepsis.

Liver histology alterations during carbon dioxide pneumoperitoneum in a porcine model

BACKGROUND

This study aimed to investigate the time course changes in liver histology during carbon dioxide (CO(2)) pneumoperitoneum in a large animal model.

METHODS

For this study, 14 white pigs were anesthetized. Liver biopsies performed 0, 1, and 2 h after establishment of CO(2) pneumoperitoneum (at 12 mmHg) and after peritoneal desufflation were sent for histologic examination. Heart rate, mean blood pressure, hepatic artery flow, portal vein flow, and aortic flow were recorded in 10-min increments. Three animals served as control subjects.

RESULTS

A statistically significant time course increase was observed in portal inflammation, intralobular inflammation, edema, sinusoidal dilation, sinusoidal hyperemia, centrilobular dilation, centrilobular hyperemia, pericentrilobular ischemia, and focal lytic necrosis scores. There were no significant changes in the control group. This eliminated an effect of anesthesia only. The portal vein flow increased as much as 21%, and the hepatic artery flow decreased as much as 31% of baseline, but these differences did not attain statistical significance. Aortic flow remained relatively stable.

CONCLUSION

Histomorphologic changes occurred, indicating liver tissue injury during CO(2) pneumoperitoneum at an intraabdominal pressure of 12 mmHg in the porcine model. Portal vein flow increased, and hepatic artery flow decreased, whereas aortic flow remained relatively unaffected in this experiment.

Regulatory processes interacting to maintain hepatic blood flow constancy: Vascular compliance, hepatic arterial buffer response, hepatorenal reflex, liver regeneration, escape from vasoconstriction

Constancy of hepatic blood flow (HBF) is crucial for several homeostatic roles. The present conceptual review focuses on interrelated mechanisms that act to maintain a constant HBF per liver mass. The liver cannot directly control portal blood flow (PF); therefore, these mechanisms largely operate to compensate for PF changes. A reduction in PF leads to reduced intrahepatic distending pressure, resulting in the highly compliant hepatic vasculature passively expelling up to 50% of its blood volume, thus adding to venous return, cardiac output and HBF. Also activated immediately upon reduction of PF are the hepatic arterial buffer response and an HBF-dependent hepatorenal reflex. Adenosine is secreted at a constant rate into the small fluid space of Mall which surrounds the terminal branches of the hepatic arterioles, portal venules and sensory nerves. The concentration of adenosine is regulated by washout into the portal venules. Reduced PFreduces the washout and the accumulated adenosine causes dilation of the hepatic artery, thus buffering the PF change. Adenosine also activates hepatic sensory nerves to cause reflex renal fluid retention, thus increasing circulating blood volume and maintaining cardiac output and PF. If these mechanisms are not able to maintain total HBF, the hemodynamic imbalance results in hepatocyte proliferation, or apoptosis, by a shear stress/nitric oxide-dependent mechanism, to adjust total liver mass to match the blood supply. These mechanisms are specific to this unique vascular bed and provide an excellent example of multiple integrative regulation of a major homeostatic organ.

Effect of carbon dioxide pneumoperitoneum on liver function following laparoscopic cholecystectomy

BACKGROUND

It has been noted that following a laparoscopic cholecystectomy (LC), liver function parameters were disturbed. The causes of this disturbance are still controversial.

PATIENTS AND METHODS

The serum levels of eight parameters of liver function were measured both before and 24 hours after surgery in 142 consecutive patients who underwent LC, 23 patients who underwent open cholecystectomy (OC), and in 25 patients who underwent a conventional hernial repair. The same anesthetic protocol was applied to all patients in the various groups and in the case of LC; the intra-abdominal pressure was maintained at 12 mmHg of CO2.

RESULTS

Twenty-four (24) hours after surgery, there was a statistically significant change of all the eight parameters studied, except alkaline phosphatase in patients who underwent LC, whereas there were only 3 patients from the OC group who had changes of alanine aminotransferase and aspartite aminotransferase and 2 patients who had raised levels of direct bilirubin, and no changes were observed among those who had conventional hernial repair. We found that 83% of the patients showed more than a 100% increase in at least one parameter, 43% showed an increase in two or more parameters, and 23% showed an increase in three or more parameters. We also observed a significant drop of total proteins and albumin levels in all patients who had LC.

CONCLUSIONS

It appears that the pneumoperitoneum plays a major role in these changes. Although these changes of liver function were of no clinical relevance in healthy patients, the safety of the procedure must nonetheless be assessed in those with underlying liver diseases.

Carbon dioxide pneumoperitoneum-related liver injury is pressure dependent: A study in an isolated-perfused organ model

BACKGROUND

Disturbed liver function tests are associated with the pneumoperitoneum applied for biliary and non-biliary laparoscopic surgical procedures. The extent, duration and reversibility of such an injury are unknown. An isolated organ model was used to assess reversibility of liver injury in a CO(2)-pneumoperitoneum-like environment.

METHODS

Rat livers (n = 63) were isolated and perfused within a chamber pressurized at 0, 3, 5, 8, 12, 15 or 18 mmHg for 60 minutes. Pressure was annulled during the ensuing 61-90 minutes in one-half of the groups and markers of liver function were measured and recorded.

RESULTS

Inflow pressure level, flow rate, effluent partial O(2) and CO(2) pressures, O(2) extraction rate, lactate dehydrogenase level, lactic to pyruvic acid ratio, and total xanthine oxidase and dehydrogenase levels became abnormal, starting at 15 minutes after a pressure >5 mmHg was applied in the chamber. Signs of injury slowly reversed towards baseline values in all groups except for the 15 mmHg and 18 mmHg-pressurized ones, even after pressure had been annulled for 30 minutes.

CONCLUSIONS

CO(2)-pneumoperitoneum-like conditions directly injured rat liver tissue to a degree which correlated with the amount of applied pressure. Damage caused by pressure >or=15 mmHg was no longer reversible if it had been applied over a 60-minute period.

Microdialysis of the rectus abdominis muscle for early detection of impending abdominal compartment syndrome

OBJECTIVE

To investigate whether microdialysis is capable of assessing metabolic derangements during intra-abdominal hypertension (IAH), and whether monitoring of the rectus abdominis muscle (RAM) by microdialysis represents a reliable approach in the early detection of organ dysfunctions in abdominal compartment syndrome (ACS).

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University animal research facility.

SUBJECTS

Fifteen isoflurane-anesthetized and mechanically ventilated Sprague-Dawley rats.

INTERVENTIONS

IAH of 20 mmHg was induced for 3 h and followed by decompression and reperfusion for another 3-h period (n = 10). Five sham-operated animals served as controls. Microdialysis was performed in the anterior gastric wall, liver, kidney, and RAM. The anterior cervical muscles served as distant reference. Glucose, lactate, pyruvate, and glycerol was analyzed throughout the 6-h experiment.

MEASUREMENTS AND MAIN RESULTS

Prolonged IAH induced significant cardiopulmonary dysfunction and persistent abdominal organ injury. Microdialysis revealed a significant increase of lactate/pyruvate and glycerol in kidney, intestine and liver, indicating ischemia, energy failure, and cell membrane damage. In addition, at 3 h IAH glucose was significantly decreased in all organs studied. The distant reference did not show any alteration of lactate/pyruvate, glycerol, and glucose over the entire 6-h observation period. In contrast to the other organs, microdialysis of the RAM showed an early and more pronounced increase of lactate, lactate/pyruvate and glycerol already at 1 h IAH. It is noteworthy that lactate, glycerol, and glucose did not completely recover upon decompression of IAH.

CONCLUSIONS

Our data suggest that continuous microdialysis in the RAM may represent a promising tool for early detecting IAH-induced metabolic derangements.

A new model for the study of the abdominal compartment syndrome in rats

BACKGROUND

The purpose of the present study was to develop of a rodent model of abdominal compartment syndrome (ACS), which allows detailed analysis of intra-abdominal hypertension (IAH)- and decompression-associated reperfusion injury.

METHODS

In 20 anesthetized and ventilated Sprague-Dawley rats an IAH of 20 mmHg was induced for 3 h by intraperitoneal infusion of gelatin polysuccinate. After decompression, an additional 3-h period of reperfusion was studied. Sham-operated animals, undergoing identical procedures without IAH induction, served as controls. Controlled hyperventilation and intravenous fluid substitution were adapted to keep PCO(2) <60 mmHg and mean arterial pressure (MAP) >100 mmHg.

RESULTS

IAH of 20 mmHg could successfully be maintained for the entire 3-h period. MAP was not affected during IAH, however, decreased upon decompression despite forced fluid resuscitation. CVP was markedly elevated during IAH, but returned to baseline after decompression. Of interest, the IAH-induced reduction of PaO(2) did not recover to baseline after decompression, indicating a persistent deterioration of gas exchange. In contrast, IAH-associated elevation of PaCO(2) normalized during reperfusion. IAH was further accompanied by metabolic acidosis, which persisted after decompression, indicating reperfusion injury. IAH was further associated with a significant increase of serum potassium, lactate, AST, LDH, bilirubin, urea, and creatinine as well as creatine kinase (CK) and CK-MB. Histomorphological analysis revealed parenchymal injury in liver, lung, intestine, and myocardium.

CONCLUSION

We established an easily reproducible ACS model in the rat, demonstrating hemodynamic deteriorations and organ dysfunctions similar as known from patients with IAH. Decompression did not restore functional deteriorations, indicating persistent post-ACS reperfusion injury. The model may be suitable to study mechanisms and novel treatment strategies in ACS.

The role of the spleen in laparoscopy-associated inflammatory response

BACKGROUND

Carbon dioxide (CO(2)) pneumoperitoneum alters the inflammatory response in animal models of sepsis. The spleen is a key organ in inflammation and its removal was predicted to modify this effect.

METHODS

The acute phase inflammatory response to lipopolysaccharide (LPS) challenge in male rats was examined for the effects of splenectomy (spx) and the technique of removal (open or laparpscopic). A series of experiments compared LPS-only controls with LPS injection 2 or 9 days following open spx, lap CO2 spx, open sham, or lap CO2 sham. The method of splenectomy was studied by randomization to control, open spx, lap CO2 spx, lap helium (He) spx, or lap air spx with LPS challenge on postoperative day 2. Serum levels of tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (INF-gamma) and, interleutin (IL) 10 were collected at multiple time points, assayed by commercial enzyme-linked immunosorbent assay, analyzed by analysis of variance.

RESULTS

Levels of TNF-alpha at 1.5 were significantly lower following open sham than following lap sham (p < 0.05). Splenectomy drastically reduced INF-gamma and TNF-alpha levels compared to controls (p < 0.05) on postoperative day 2. No method of spx preserved TNF-alpha or INF-gamma responses. Recovery of TNF-alpha response on day 9 was delayed in the spx groups.

CONCLUSIONS

Splenectomy dramatically reduces TNF-alpha and INF-gamma responses to LPS challenge, although by different mechanisms. Pneumoperitoneum-mediated modulation of the septic inflammatory response is partially dependent on the spleen.

Postoperative changes in liver function tests: randomized comparison of low- and high-pressure laparoscopic cholecystectomy

BACKGROUND

Pneumporeitoneum at 14 mmHg causes dangerous hemodynamic disturbances in some patients, leading to splanchnic ischemia. Laparoscopic cholecystectomy (LC) using low-pressure pneumoperitoneum (7 mmHg) minimizes adverse hemodynamic effects on hepatic portal blood flow and hepatic function. This study evaluated the changes in liver function tests after high-pressure LC (HPLC; 14 mmHg) and low-pressure LC (LPLC; 7 mmHg).

METHODS

For this study, 50 patients were randomly assigned to undergo either HPLC (n = 25) or LPLC (n = 25) Liver function tests including total bilirubin, gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were obtained preoperatively, then 24 and 48 h postoperatively. All patients had normal values on the preoperative liver function tests. The anesthesiologic protocol was uniform.

RESULTS

The findings showed that ALT after 24 h (LPLC: 1473.72 +/- 654.85; HPLC: 2233.74 +/- 1247.33; p = 0.0096) and 48 h (LPLC: 1322.99 +/- 601.51; HPLC 2007.80 +/- 747.55; p = 0.0008) and AST after 24 h (LPLC: 1189.96 +/- 404.79 i.j.; HPLC: 1679.40 +/- 766.13; p = 0.0069) were increased in the patients who underwent HPLC. The AST levels after 48 h were statistically unchanged from baseline in both groups. Total bilirubin, ALP, and GGT levels remained unchanged from baseline in both groups, without a significant difference between the two groups.

CONCLUSIONS

Because LPLC minimizes adverse hemodynamic effects on hepatic function, a low-pressure pneumoperitoneum should be considered for patients with compromised liver function, particularly those undergoing prolonged laparoscopic surgery.

Comparison of postoperative hepatic function between laparoscopic and open cholecystectomy

OBJECTIVE

In this prospective study, we evaluated the effects of pneumoperitoneum on hepatic function during laparoscopic (LC) and open cholecystectomy (OC).

SUBJECTS AND METHODS

One hundred patients who underwent LC (n = 50) or OC (n = 50) were included in the study. The groups were similar in age, sex, weight and height. Following liver function tests (total bilirubin; gamma-glutamyltransferase, GGT; alkaline phosphatase, ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) were obtained preoperatively and at 24 and 48 h postoperatively. Similar anesthesiologic protocol was used for both LC and OC. During LC, the intra-abdominal pressure was maintained within the conventional range of 12-14 mm Hg.

RESULTS

Total bilirubin, ALP, GGT and LDH levels remained unchanged from baseline in both groups without significant difference between them. A higher number of patients had increased values of ALT (26/50 vs. 5/50) and AST (23/50 vs. 6/50) in LC compared to OC group. Although the difference was statistically significant (p < 0.000 for ALT and p = 0.0004 for AST) the increased level decreased at 48 compared to 24 h.

CONCLUSION

The results indicate that LC is associated with transient elevation of ALT and AST. The disturbances in the function of the liver after LC are self-limited and not associated with any morbidity in patients with a normal liver function.

The Effects of Intraabdominally Insufflated Carbon Dioxide on Hepatic Blood Flow During Laparoscopic Surgery Assessed by Transesophageal Echocardiography

Conflicting results have been published about the effects of carbon dioxide (CO(2)) pneumoperitoneum on splanchnic and liver perfusion. Several experimental studies described a pressure-related reduction in hepatic blood flow, whereas other investigators reported an increase as long as the intraabdominal pressure (IAP) remained less than 16 mm Hg. Our goal in the present study was to investigate the effects of insufflated CO(2) on hepatic blood flow during laparoscopic surgery in healthy adults. Blood flow in the right and middle hepatic veins was assessed in 24 patients undergoing laparoscopic surgery by use of transesophageal Doppler echocardiography. Hepatic venous blood flow was recorded before and after 5, 10, 20, 30, and 40 min of pneumoperitoneum, as well as 1 and 5 min after deflation. Twelve patients undergoing conventional hernia repair served as the control group. The induction of pneumoperitoneum produced a significant increase in blood flow of the right and middle hepatic veins. Five minutes after insufflation of CO(2) the median right hepatic blood flow index increased from 196 mL/min/m(2) (95% confidence interval (CI), 140-261 mL/min/m(2)) to 392 mL/min/m(2) (CI, 263-551 mL/min/m(2)) (P < 0.05) and persisted during maintenance of pneumoperitoneum. In the middle hepatic vein the blood flow index increased from 105 mL/min/m(2) (CI, 71-136 mL/min/m(2)) to 159 mL/min/m(2) (CI, 103-236 mL/min/m(2)) 20 min after insufflation of CO(2). After deflation blood flow returned to baseline values in both hepatic veins. Conversely, in the control group hepatic blood flow remained unchanged over the entire study period. We conclude that induction of CO(2) pneumoperitoneum with an IAP of 12 mm Hg is associated with an increase in hepatic perfusion in healthy adults.

The effect of timing of pneumoperitoneum on the inflammatory response

BACKGROUND

We examined the effects of an identical period of pneumoperitoneum applied at three different time points after lipopolysaccharide (LPS) challenge. Two different insufflation gases were also compared.

METHODS

Male rats (n = 70) were injected intravenously with 1 mg/kg of LPS (time 0). The time relationship between a 1.5-h period of insufflation and initial LPS stimulation was the experimental variable. All rats were killed 6 h after injection. CO2 and helium insufflation were investigated. Ten control rats received LPS only. Serum interleukin-6 (IL-6) levels were determined by enzyme-linked immunosorbent assay (ELISA). Hepatic expression of alpha2-macroglobulin, beta-fibrinogen, and metallothionein were measured by Northern blot analysis. Statistical analysis was performed using one-way analysis of variance (ANOVA).

RESULTS

Expression of alpha2-macroglobulin mRNA was lower in CO2 groups compared to the control group (p < 0.05 at time 120 and 270). beta-Fibrinogen message was diminished in CO2 0 and 120 groups compared to control. Serum levels of IL-6 and expression of metallothionein mRNA did not show significant differences between groups.

CONCLUSIONS

These findings suggest that CO2 pneumoperitoneum downregulates the inflammatory response to LPS challenge. Start time of CO2 insufflation does not appear to alter hepatic expression of acute phase genes. The mechanism of alpha2-macroglobulin downregulation does not appear to be due to IL-6.

Microcirculation and excretory function of the liver under conditions of carbon dioxide pneumoperitoneum

BACKGROUND

To date, the effects of increased abdominal pressure, as given during carbon dioxide (CO(2)) pneumoperitoneum, on hepatic microcirculation and biliary excretion are unknown.

METHODS

Using a custom-made peritoneal cavity chamber, we performed intravital microscopy of the left liver lobe under conditions of CO(2) pneumoperitoneum in a rat model. In addition, biliary excretion was assessed.

RESULTS

The establishment of a CO(2) pneumoperitoneum of 4 or 8 mmHg resulted in sinusoidal perfusion failure that was more pronounced in the periportal regions than in the midzonal and pericentral regions of the liver acinus. Biliary excretion was considerably reduced at an intraabdominal pressure of 8 mmHg. Leukocyte-endothelial cell interactions increased significantly in both hepatic sinusoids and postsinusoidal venules.

CONCLUSION

Alterations in hepatic microcirculation and liver function must be taken into consideration in any kind of laparoscopic surgery and may be of particular clinical relevance in patients with liver pathology.