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.

Patients admitted as a case of acute cholecystitis, ascending cholangitis, gallbladder stones with obstructive jaundice, gallbladder stones with pancreatitis, history of chronic liver disease, gallbladder empyema, gangrene or perforation and gallbladder malignancy were excluded. Moreover, patients who experienced postoperative biliary tree complications were also excluded. Only patients who were admitted electively for gallbladder stones were included in the study. The LFTs that were ordered pre and postoperatively were: ALP, ALT, AST, GGT, direct bilirubin and total bilirubin.
Patients were allocated randomly into two groups. Group A included patients who underwent dissection of the gallbladder by the Maryland dissecting forceps connected to the electro-cautery device, while group B included patients who underwent dissection of the gallbladder by Hook instrument, connected to the same electro-cautery device.
Setting LC operations were performed by a single surgeon and following the standard method. In all patients, the same electrocautery device (Karl-Storz) was utilized on a monopolar electrode and coagulation waveform mode, with a pre-adjusted power of 30 w. Group A underwent standard LC using Maryland dissecting forceps (Karl-Storz 36 cm length). Group B underwent standard LC using Hook dissecting instrument (Karl-Storz 36 cm length).
Patients brought to the operating room received a shot of 1 g iv. cefazolin preoperatively, after the formal surgical safety checklist was performed. The abdomen was prepared and draped in a sterile fashion, in a supine position, after general anesthesia and intubation. Supra-umbilical midline incision was made and open technique was used to enter the peritoneal cavity and to establish the pneumoperitoneum at a standard pressure of 14 mmhg. The peritoneal cavity was inspected without abnormalities in all patients.
The patient was placed in reverse Trendelenburg position with the right side up. Omental attachments to the gallbladder were gently swept away until an atraumatic grasper could be used to retract the fundus of the gallbladder, superior-laterally over the dome of the liver. The infundibulum was identified and subsequently retracted laterally, toward the right lower quadrant using another grasper. This maneuver exposed Calot's triangle. The peritoneum overlying the gallbladder infundibulum was incised with either Maryland in group A or Hook in group B, anteriorly. The triangle was dissected to expose the cystic duct, the cystic artery and lymph node. Once these structures were carefully identified and the critical view of safety was adequately achieved, the cystic artery was divided first, followed by further dissection of the triangle until it was determined that the only structure remaining entering the gallbladder was the cystic duct, it was then doubly clipped and divided.
Next, the peritoneal attachments between the gallbladder and its liver bed were dissected (by Maryland in group A and by Hook in group B). The gallbladder fossa and cystic artery stump were inspected to ensure adequately secured hemostasis. The gallbladder, once freed, was placed in an endoscopic retrieval bag and removed from the abdomen through the supra-umbilical port. The same anesthetic protocol was used for both group of patients. The Hook and Maryland dissectors are of the reusable types. After each operation, both dissectors undergo the same sterilization procedure. Accordingly, the total cost for each dissector is the same.

Statistical analysis
Statistical analyses were performed using IBM SPSS Statistics Software (v.21), 2012. Categorical variables were described using the frequency distribution, while continuous variables were described using the mean ± standard error of the mean. Data were blocked into two groups and examined at the 95% confidence interval using Pearson's chi-square test of association for categorical variables and student's t-test for continuous variables, after testing for distribution normality.

Results
A total of 137 patients who underwent elective LC for gallstones were included in the study; 86 patients were excluded. The analyzed patients were divided into two groups; A and B. Group A included 68 patients (28 males and 40 females), while group B was composed of 69 patients (24 males and 45 females). The mean age for group A and B was 46.5 and 40.0 (p > 0.05), respectively.
The patients mean preoperative and postoperative LFTs values are illustrated in Table 1. For the Maryland, there was no statistical difference between the preoperative and 1-day postoperative values for ALP, direct bilirubin and GGT. However, the 1-day postoperative values for total bilirubin, ALT and AST were significantly higher than the preoperative values. Similarly, for the Hook in group B, there was no statistical difference between the preoperative    Table 2 summarizes the differences between the changes in the preoperative and 1-day postoperative values for each test for both groups. There were no statistical differences for both groups in all LFTs. In addition, all patients had returned normal values of LFTs after 1 week postoperatively.

Discussion
To the best of our knowledge, 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.
The significant elevation of both ALT and AST points toward hepatocellular injury, which is contributed mostly to by the reduction in the hepatic blood flow due to an increase in intra-abdominal pressure [7][8][9][10]. There are two situations that can contribute to the alterations of LFTs: the increased intra-abdominal pressure and the use of CO2 to induce pneumoperitoneum. Pneumoperitoneum induces hepatic hypoperfusion by increasing intra-abdominal pressure. The normal portal blood pressure is approximately 8 mmHg, but the intra-abdominal pressure employed in laparoscopy can rise up to 16 mmHg. Pneumoperitoneum causes a reduction of portal venous inflow, marked reduction in liver perfusion and inadequate oxygen supply, with the consequence of hepatocellular injury [14]. This hepatocellular ischemic injury, due to increased abdominal pressure, can explain the elevation of ALT and AST as they are more sensitive and specific for hepatocellular injury [15]. Also, the anesthetic procedures and drugs used can induce hepatic toxic injury [16][17][18]. Moreover, CO2 employed to induce the pneumoperitoneum has a vasoconstrictive effect, which can reduce visceral blood flow [19]. Two studies by Hasukic et al. and Morino et al. demonstrated a pressure-dependent decrease in hepatic blood flow and enzyme elevations of ALT and AST [2,4]. However, postoperative bilirubin, ALP and GGT were not significantly elevated [9,20]. Eryilmaz et al. used indocyanine green elimination tests (ICG-PDR) as an indicator for liver function. In their trial, a significant decrease in ICG-PDR values in the standard pressure (14 mmHg) pneumoperitoneum was observed, when compared with the low-pressure group (10 mmHg) [21].
Furthermore, the alteration in LFTs could be contributed to by the use of electrocautery device. Hochstädetr et al. demonstrated a significant rise in liver enzymes (ALT and AST) after surgery, in both monopolar cutter and harmonic scalpel. However, postoperative values of these two enzymes were significantly higher in patients operated on using the monopolar cutter [22]. It is obvious that the usage of ultrasonic energy is better than electrocautery in LC in terms of shorter operating time, hospital stay sick leave and lower gallbladder perforation risk [23][24][25][26].
After these hypotheses and explanations, an important question arises: is it necessary to do routine testing of LFTs pre-and post-elective cases of LC? The assessment of preoperative LFTs is usually done to find if there is any hepatic disease or biliary obstructions in order to take the appropriate management. Tan et al. proposed that for patients with liver disease or any patients exhibiting altered LFTs before the surgery, laparoscopy might not be the right choice because it can further deteriorate hepatic function [3]. On the other hand, Pavlidis et al. suggested that LC can be safely carried out in patients with child classes A and B liver cirrhosis, without a significant increase in complications [27]. In fact, LC is not the only procedure associated with elevated postoperative LFTs. Other laparoscopic operations such as colorectal surgeries or other abdominal surgery have also been associated with altered postoperative LFTs [20,28]. Early elevation of LFTs after surgery usually returns to normal without intervention. Ahmad confirmed that mild-to-moderate elevation in preoperative LFTs may not be associated with any serious effect [29]. In the absence of clinical indications, routine preoperative or postoperative liver function testing is unnecessary [29]. In our study population, the LFTs for all patients returned to baseline level after 1 week.
Another factor that would play a role in the elevation of LFTs is the duration of surgery. Singal et al. demonstrated that the mean duration of surgery in the LC group was 57.7 min and in the open cholecystectomy group the mean duration of surgery was 61.8 min, which is nonsignificant (p = 0.109) and made both the groups comparable. In the LC group, they determined that the patient with minimum duration of surgery (40 min) had less elevation in liver enzymes (serum bilirubin, AST and ALT) as compared with the patient with maximum duration (90 min) of surgery [30].

Conclusion
In LC, no differences were found between the utilization of Maryland and Hook dissectors in term of changes in LFTs. The elevation of LFTs seems to be attributable to other factors.

Future perspective
As there is no difference between the Mayland and Hook dissectors, surgeons would have the choice to use any type of dissectors depending on their training and skills. Also, pneumoperitoneum would be the most important factor contributing to the elevation of LFTs after laparoscopic surgery. Further research should be conducted to find the optimal level of pressure. In addition, further investigations and studies should be performed to determine which patients should avoid laparoscopic surgery based on their perioperative clinical and laboratory status.

Summary points
• Elevation in levels of liver function tests following laparoscopic cholecystectomy is an apparent cause of apprehension to the surgeon. • Pneumoperitoneum is a main contributing factor.
• No study was heretofore conducted to compare the effect of different techniques of dissection in laparoscopic cholecystectomy (Maryland vs Hook). • This study includes patients who underwent laparoscopic cholecystectomy and were divided into two groups.
Group A included patients who underwent dissection by Maryland dissecting forceps while group B underwent Hook dissecting instrument. • Liver function tests were measured preoperatively and at 1 day and 1 week postoperatively.
• No statistical differences were seen in the variation of liver function tests between the Maryland and Hook.
• It seems that the dissector type has no effect on the alteration of liver function tests.

Author contributions
All authors conceived the concept of the study. All authors were involved in the design of the research and wrote the paper. All authors were involved in data collection. A Aleshawi analyzed the data. All authors read, edited and approved the final version of the manuscript.

Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research
The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.The authors state that they have obtained verbal and written informed consent from the patient/patients for the inclusion of their medical and treatment history within this case report.
Written informed consent was obtained from the patients for publication. Institutional approval was obtained from the Institutional Review Board at Jordan University of Science and Technology. This study was conducted in accordance with the Declaration of Helsinki.

Data availability
The datasets generated and analyzed during the current study are available from the corresponding author.

Open access
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