Sascha A. Müller

Safe and early discharge after colorectal surgery due to C-reactive protein: a diagnostic meta-analysis of 1832 patients.

Objective:To assess the predictive value of C-reactive protein (CRP) level for postoperative infectious complications after colorectal surgery. Background:Postoperative infectious complications after colorectal surgery are frequent and associated with relevant short- and long-term sequelae. Therefore, the identification of a diagnostic tool for early recognition of postoperative infectious complications is of cardinal importance. Methods:A meta-analysis was performed for diagnostic studies evaluating CRP as a predictor for postoperative infectious complications on days 1 to 5 after colorectal surgery. Results:Six studies including a total of 1832 patients were identified. The best performance of CRP to predict postoperative infectious complications was on postoperative day 4, on which the mean CRP cutoff value was 135 mg/L (SD: 10 mg/L), the pooled sensitivity 68% (95% CI: 57%–79%), the specificity 83% (95% CI: 77%–90%) and the negative predictive value 89% (95% CI: 87%–92%). The pooled area under the receiver operating characteristic curve was 0.81 (95% CI: 0.73–0.89). Conclusions:This diagnostic meta-analysis of 1832 patients-–the first in the literature–-provides compelling evidence that C-reactive protein on postoperative day 4 has a high negative predictive value for infectious complications of 89%. Therefore, CRP measurement allows safe and early discharge of selected patients after colorectal surgery.

In vivo accuracy assessment of a needle-based navigation system for CT-guided radiofrequency ablation of the liver.

Computed tomography (CT)-guided percutaneous radiofrequency ablation (RFA) has become a commonly used procedure in the treatment of liver tumors. One of the main challenges related to the method is the exact placement of the instrument within the lesion. To address this issue, a system was developed for computer-assisted needle placement which uses a set of fiducial needles to compensate for organ motion in real time. The purpose of this study was to assess the accuracy of the system in vivo. Two medical experts with experience in CT-guided interventions and two nonexperts used the navigation system to perform 32 needle insertions into contrasted agar nodules injected into the livers of two ventilated swine. Skin-to-target path planning and real-time needle guidance were based on preinterventional 1 mm CT data slices. The lesions were hit in 97% of all trials with a mean user error of 2.4 +/- 2.1 mm, a mean target registration error (TRE) of 2.1 +/- 1.1 mm, and a mean overall targeting error of 3.7 +/- 2.3 mm. The nonexperts achieved significantly better results than the experts with an overall error of 2.8 +/- 1.4 mm (n=16) compared to 4.5 +/- 2.7 mm (n=16). The mean time for performing four needle insertions based on one preinterventional planning CT was 57 +/- 19 min with a mean setup time of 27 min, which includes the steps fiducial insertion (24 +/- 15 min), planning CT acquisition (1 +/- 0 min), and registration (2 +/- 1 min). The mean time for path planning and targeting was 5 +/- 4 and 2 +/- 1 min, respectively. Apart from the fiducial insertion step, experts and nonexperts performed comparably fast. It is concluded that the system allows for accurate needle placement into hepatic tumors based on one planning CT and could thus enable considerable improvement to the clinical treatment standard for RFA procedures and other CT-guided interventions in the liver. To support clinical application of the method, optimization of individual system modules to reduce intervention time is proposed.

Current concepts in transplant surgery: liver transplantation today

IntroductionThe discipline of liver transplantation (LTx) has been developed over the past decades, and LTx is now considered the gold standard for the treatment of patients with end-stage liver diseases and early liver tumors in cirrhotic livers. This procedure is now performed routinely in many transplant centers, and it has provided an enormous technical innovation to the field of hepatobiliary surgery. Allocation decision of liver organs is based on medical need and timing.Materials and methodsThe Mayo Model for End Stage Liver Disease based on patient-specific criteria was developed and applied to prioritize patients on the waiting list. From the donor aspects of LTx, sources of organ, excluding xenotransplantation, can be brain-dead donors, living donors, and non-heart-beating donors. Today, the majority of livers are procured from cadaveric donors. In addition to the conventional LTx, other types are living-donor LTx, reuse of grafts as domino transplantation, ex situ as well as in situ split LTx, and reduced-size LTx. The transplantation procedure consists of several steps including donor selection and management, liver procurement and preservation, back-table preparation, recipient operation with liver implantation, postoperative care, immunosuppression, and follow-up.ResultsThe postoperative complications are divided into surgical, non-surgical, and multifactorial complications. Surgical complications account about 34% of morbidities after LTx and are mainly categorized to vascular and biliary complications. The main medical ones are non-surgical bleeding and infections. The multifactorial complications include primary non- or poor function and small-for-size syndrome. The pretransplant outcome predictors of LTx can be divided into donor, recipient, operative, and postoperative factors.ConclusionLTx is now considered a safe and standardized procedure with a substantially improved graft and patient survival and acceptable morbidity rates. However, the new problems, including recurrence of hepatitis C or hepatocellular carcinoma, chronic biliary complications, opportunistic infections, and development of de-novo malignancies are the major problems affecting the long-term outcome of transplanted patients.

Diagnostic accuracy of C-reactive protein and white blood cell counts in the early detection of inflammatory complications after open resection of colorectal cancer: a retrospective study of 1,187 patients.

Purpose Although widely used, there is a lack of evidence concerning the diagnostic accuracy of C-reactive protein (CRP) and white blood cell counts (WBCs) in the postoperative period. The aim of this study was to evaluate the diagnostic accuracy of CRP and WBCs in predicting postoperative inflammatory complications after open resection of colorectal cancer.

Mesohepatectomy as an Option for the Treatment of Central Liver Tumors

BACKGROUND Despite substantial improvements in intra- and postoperative management of extended hemihepatectomy as the curative option for treatment of central liver tumors, the high morbidity and mortality rates accompanying the procedure still represent major obstacles. Mesohepatectomy preserves up to 35% more functional liver tissue than extended hepatectomy, but it has not been widely applied, perhaps because of its complexity as a resection method. STUDY DESIGN Forty-eight consecutive patients (29 men and 19 women) with centrally located liver tumors underwent mesohepatectomy. Peri- and postoperative morbidity and mortality rates were prospectively evaluated and analyzed. Mean age of the patients was 60.7 years. Indications for mesohepatectomy were liver metastasis (n = 29), hepatocellular carcinoma (n = 5), gallbladder carcinoma (n = 4), cholangiocellular carcinoma (n = 4), hemangioma (n = 2), and other benign diseases (n = 4). RESULTS Mean operative time was 238 minutes (range 65 to 480 minutes) and mean intraoperative blood loss was 1,120 mL (range 100 to 5,000 mL). Mean amount of intraoperative red blood cells and fresh frozen plasma transfusion was 3.6 U (range 1 to 12 U) and 3.8 U (range 2 to 14 U), respectively. Mean postoperative hospitalization was 15.8 days (range 6 to 104 days). Postoperative surgical complications were seen in 18.8% of patients (n = 9) and included liver failure (n = 1), intraabdominal abscess (n = 1), bilioma or bile leakage (n = 4), hemorrhage and hematoma (n = 2), peritonitis because of intestinal perforation (n = 1), and wound infection (n = 1). One patient (2%) died in the early postoperative phase from portal vein bleeding and disseminated intravascular coagulation, followed by liver failure. CONCLUSIONS Compared with extended liver resection, mesohepatectomy clearly leads to less parenchymal loss. Although it is a technically difficult operation and requires special attention to prevent surgical complications, it is justified in selected patients with centrally located tumors and is a feasible and safe alternative to extended liver resection.

The need for venovenous bypass in liver transplantation.

Since introduction of the conventional liver transplantation (CLTx) by Starzl, which was based on the resection of recipient inferior vena cava (IVC) along the liver, the procedure has undergone several refinements. Successful use of venovenous bypass (VVB) was first introduced by Shaw et al., although in recent decades there has been controversy regarding the routine use of VVB during CLTx. With development of piggyback liver transplantation (PLTx), the use of caval clamping and VVB is avoided, leading to fewer complications related to VVB. However, some authors still advocate VVB in PLTx. The great diversity among centers in their use of VVB during CLTx, or even along the PLTx technique, has led to confusion regarding the indication setting for VVB. For this reason, we present an overview of the use of VVB in CLTx, the target of patients for whom VVB could be beneficial, and the needs assessment of VVB for patients undergoing PLTx. Recent studies have shown that with the advancement of surgical skills, refinement of surgical techniques, and improvements in anesthesiology, there are only limited indications for doing CLTx with VVB routinely. PLTx with preservation of IVC can be performed in almost all primary transplants and in the majority of re-transplantations without the need for VVB. Nevertheless, in a few selective cases with severe intra-operative hemodynamic instability, or with a failed test of transient IVC occlusion, the application of VVB is still justifiable. These indications should be judged intra-operatively and the decision is based on each centers preference.

Respiratory motion compensation for CT-guided interventions in the liver

Computed tomography (CT) guided minimally invasive procedures in the liver, such as tumor biopsy and thermal ablation therapy, require precise targeting of hepatic structures that are subject to breathing motion. To facilitate needle placement, we introduced a navigation system which uses needle-shaped optically tracked navigation aids and a real-time deformation model to continuously estimate the position of a moving target. In this study, we assessed the target position estimation accuracy of our system in vitro with a custom-designed respiratory liver motion simulator. Several real-time compatible transformations were compared as a basis for the deformation model and were evaluated in a set of experiments using different arrangements of three navigation aids in two porcine and two human livers. Furthermore, we investigated different placement strategies for the case where only two needles are used for motion compensation. Depending on the transformation and the placement of the navigation aids, our system yielded a root mean square (RMS) target position estimation error in the range of 0.7 mm to 2.9 mm throughout the breathing cycle generated by the motion simulator. Affine transformations and spline transformations performed comparably well (overall RMS < 2 mm) and were considerably better than rigid transformations. When two navigation aids were used for motion compensation instead of three, a diagonal arrangement of the needles yielded the best results. This study suggests that our navigation system could significantly improve the clinical treatment standard for CT-guided interventions in the liver.

Precision targeting of liver lesions with a needle-based soft tissue navigation system

In this study, we assessed the targeting precision of a previously reported needle-based soft tissue navigation system. For this purpose, we implanted 10 2-ml agar nodules into three pig livers as tumor models, and two of the authors used the navigation system to target the center of gravity of each nodule. In order to obtain a realistic setting, we mounted the livers onto a respiratory liver motion simulator that models the human body. For each targeting procedure, we simulated the liver biopsy workflow, consisting of four steps: preparation, trajectory planning, registration, and navigation. The lesions were successfully hit in all 20 trials. The final distance between the applicator tip and the center of gravity of the lesion was determined from control computed tomography (CT) scans and was 3.5 +/- 1.1 mm on average. Robust targeting precision of this order of magnitude would significantly improve the clinical treatment standard for various CT-guided minimally invasive interventions in the liver.

A single center experience of combined liver kidney transplantation

With advancements in the operative techniques, patient survival following liver transplantation (LTx) has increased substantially. This has led to the acceleration of pre‐existing kidney disease because of immunosuppressive nephrotoxicity making additional kidney transplantation (KTx) inevitable. On the other hand, in a growing number of patients on the waiting list to receive liver, long waiting time has resulted in adverse effect of decompensated liver on the kidney function. During the last two decades, the transplant community has considered combined liver kidney transplantation (CLKTx) to overcome this problem. The aim of our study is to present an overview of our experience as well as a review of the literature in CLKTx and to discuss the controversy in this regard. All performed CLKTx (n = 22) at our institution as well as all available reported case series focusing on CLKTx are extracted. The references of the manuscripts were cross‐checked to implement further articles into the review. The analyzed parameters include demographic data, indication for LTx and KTx, duration on the waiting list, Model for End‐Stage Liver Disease (MELD) score, Child‐Turcotte‐Pugh (CTP) score, immunosuppressive regimen, post‐transplant complications, graft and patient survival, and cause of death. From 1988 to 2009, a total of 22 CLKTx were performed at our institution. The median age of the patients at the time of CLKTx was 44.8 (range: 4.5–58.3 yr). The indications for LTx were liver cirrhosis, hyperoxaluria type 1, polycystic liver disease, primary or secondary sclerosing cholangitis, malignant hepatic epithelioid hemangioendothelioma, cystinosis, and congenital biliary fibrosis. The KTx indications were end‐stage renal disease of various causes, hyperoxaluria type 1, polycystic kidney disease, and cystinosis. The mean follow‐up duration for CLKTx patients were 4.6 ± 3.5 yr (range: 0.5–12 yr). Overall, the most important encountered complications were sepsis (n = 8), liver failure leading to retransplantation (n = 4), liver rejection (n = 3), and kidney rejection (n = 1). The overall patient survival rate was 80%. Review of the literature showed that from 1984 to 2008, 3536 CLKTx cases were reported. The main indications for CLKTx were oxalosis of both organs, liver cirrhosis and chronic renal failure, polycystic liver and kidney disease, and liver cirrhosis along with hepatorenal syndrome (HRS). The most common encountered complications following CLKTx were infection, bleeding, biliary complications, retransplantation of the liver, acute hepatic artery thrombosis, and retransplantation of the kidney. From the available data regarding the need for post‐operative dialysis (n = 673), a total of 175 recipients (26%) required hemodialysis. During the follow‐up period, 154 episodes of liver rejection (4.3%) and 113 episodes of kidney rejection (3.2%) occurred. The cumulative 1, 2, 3, and 5 yr survival of both organs were 78.2%, 74.4%, 62.4%, and 60.9%, respectively. Additionally, the cumulative 1, 2, 3, and 5 yr patient survival were 84.9%, 52.8%, 45.4%, and 42.6%, respectively. The total number of reported deaths was 181 of 2808 cases (6.4%), from them the cause of death in 99 (55%) cases was sepsis. It can be concluded that there is still no definitive evidence of better graft and patient survival in CLKTx recipients when compared with LTx alone because of the complexity of the exact definition of irreversible kidney function in LTx candidates. Additionally, CLKTx is better to be performed earlier than isolated LTx and KTx leading to the avoidance of deterioration of clinical status, high rate of graft loss, and mortality. Shorter graft ischemia time and more effective immunosuppressive regimens can reduce the incidence of graft malfunctioning in CLKTx patients. Providing a model to reliably determine the need for CLKTx seems necessary. Such a model can be shaped based upon new and precise markers of renal function, and modification of MELD system.

On combining internal and external fiducials for liver motion compensation

This paper presents an in-vivo accuracy study on combining skin markers (external fiducials) and fiducial needles (internal fiducials) for motion compensation during liver interventions. We compared the target registration error (TRE) for different numbers of skin markers ns and fiducial needles nf, as well as for different transformation types, in two swine using the tip of an additional tracked needle as the target. During continuous breathing, nf had the greatest effect on the accuracy, yielding mean root mean square (RMS) errors of 4.8 ± 1.1 mm (nf = 0), 2.0 ± 0.9 mm (nf = 1) and 1.7 ± 0.8 mm (nf = 2) when averaged over multiple tool arrangements (n = 18, 36, 18) with ns = 4. These values correspond to error reductions of 11%, 64% and 70%, respectively, compared to the case when no motion compensation is performed, i.e., when the target position is assumed to be constant. At expiration, the mean RMS error ranged from 1.1 mm (nf = 0) to 0.8 mm (nf = 2), which is of the order of magnitude of the target displacement. Our study further indicates that the fiducial registration error (FRE) of a rigid transformation reflecting tissue motion generally correlates strongly with the TRE. Our findings could be used in practice to (1) decide on a suitable combination of fiducials for a given intervention, considering the trade-off between high accuracy and low invasiveness, and (2) provide an intra-interventional measure of confidence for the accuracy of the system based on the FRE.