In the present study 31.76 % (175/551) of patients were overweight and obese. We identify obesity as the most important risk factor for conversion mainly for inadequate exposure of the surgical field and more surgical blood loss and a longer operation time were needed in the obesity patients. However our findings were not consistent with Troisi et al. analysis. Maybe comparing with non-Asians, Asian population with the same BMI is considered to have a greater volume of intraperitoneal fat than subcutaneous fat and with more difficulty to expose the upper part of the transection plane. Although, conversion could not been considered as a failure of the laparoscopic approach, this makes some of the benefits lost. In this setting, conversion was found associated with a longer hospital stay compared with fully laparoscopic liver resection. Interestingly, there was no difference in complications between patients who underwent conversion and those who did not. It was likely that we use Clavien-Dindo classification system, which could not clearly reflect conversion related wound and pulmonary infection. And there would be a bias due to retrospective analysis. The conversion rate in present study was 13.1 % (n = 72), which corresponds to rates described in the literature.[13,15] The main reason for conversion was unclear exposure (41.67 %, 5.4 % of all patients), and the second cause was adhesion (26.39 %, 3.4 % of all patients). Our findings are not consistent with the most opinions that bleeding is the main technical difficulty.[13,16,17] This may be attributed to our special laparoscopic skill of regional occlusion of liver inflow and outflow, and well-scraping and coagulating function of LPMOD, to providing a clear view.[10,18] Another explanation could be that there was little portion of major liver resection enrolled in this study that was much more difficult to control bleeding laparoscopically.
Not inline with former studies that obese patients have a worse outcome than their leaner counterparts,[19,20] our results showed that overweight and obese patients had a lower complication rate (8.57 %) than the overall complication rate (11.98 %). One causes may be that obesity has a protective effect for adequate fat storage, better nutrition, and systemic insulin resistance that underweight people do not have.[21,22] Another possible causes may be the BMI could not adequately reflect adiposity for Asian people, who had more body fat than Europeans. However, the patients in the underweight group had an increased rate of complications (22.86 %), but the increase did not demonstrate significance. Patients with a low BMI may be with nutritional damage, possible immune deficiency and a lower physiologic reserve and thus can't withstand the hepatic resection coupled with other therapies. Also weight loss or low serum albumin levels of liver disease would be contributed to the complications.
Our study also aimed to verify the risk factors of conversion and complications. And our data revealed that obesity and surgical site of left lobe were the risk factors of conversion; abdominal surgery history and type of left and right hepatectomy were the risk factors of complication. The major finding was that conversion rate was statistically significant associated with left hemihepatectomy which also had a bit longer surgical time. For patients that we enrolled over the 15 years, the selected criteria were mostly left lateral lobe and left lobe at the early stage. Undoubtedly, a significant learning curve would account for initially higher conversion rates. And the left liver lobe is the most frequent location of hepatolithiasis, for there is an acute angle when the left hepatic duck reach the common hepatic duct.[23,24] Thus, it will take more time for surgeons to deal with the stones. But the right lobectomy, which is considered the most technically challenging with uncontrollable bleeding, did not increase conversion rate. One possible explanation is that for the small number of right lobectomy patients enrolled, surgeons attempted to choose laparoscopic approach to right hemihepatectomy until they have experienced a learning curve. In our study we found right and left hemihepatectomy were the independent predictive factors of complications. It is easy to understand laparoscopic approach to right hemihepatectomy with higher complication rate is due to the less hepatic reserve and uncontrolled bleeding. Interestingly, our result showed a significantly greater proportion of complications occurred in the laparoscopic left hemihepatectomy. This observation may be accounted for the fact that the greater number of left lobectomy patients were with hepatilithiasis, which is easy combined with biliary tract infection, leading to bile leakage and infection postoperatively.
Not compatible with the conventional view that prior abdominal operation would increase the incidence of conversion rate duo to the sequel of peritoneal adhesions, in the present study we discovered that abdominal surgery history did not increase conversion rate but increaseed complications. Maybe more proportion of patients with prior abdominal surgery history occurred in the right hepatectomy was the possible cause of higher complication rate.
Moreover, we found that postoperative LOS was significantly superior in converted patients of obese group. We speculate that although obesity did not increase the total complications after LH, it may delay the healing process of the open-wound and increase the postoperative hospitalization for its potential increased tension on the abdominal incision and tissue hypoperfusion. As highlighted by this finding, laparoscopy approach compared with open liver resection in obese patients can speed up prognosis and shorten hospitalization.
Our limitation is that the data have been retrospectively analyzed and they were from a single institution. The results of present study pertain to patients from China and hence may not be generalized to other populations. It was a retrospective observational and with selection bias, which may cloud the significant differences in outcome. We only used BMI to estimate obesity, which was not enough to assess the abdominal adiposity of Asian people.
We would also like to emphasize that our findings maybe not applicable to all the surgeons, for there were only three surgeons in a single team that performed all procedures.
BMC Anesthesiol. 2016;16(29) © 2016 BioMed Central, Ltd.