Hepatic Hemodynamic Changes Following Stepwise Liver Resection

Postoperative Management of Portal Vein Arterialization: An Interdisciplinary Institutional Approach

Portal vein arterialization (PVA) is a surgical procedure that plays a crucial role in hepatic vascular salvage when hepatic artery flow restoration remains elusive. Dedicated diagnostic vascular imaging and the timely management of PVA shunts are paramount to preventing complications, such as portal hypertension and thrombosis. Regrettably, a lack of standardized postoperative management protocols for PVA has increased morbidity and mortality rates post-procedure. In response to this challenge, we developed a PVA standard operating procedure (SOP) tailored to the needs of interventional radiologists. This SOP is designed to harmonize postoperative care, fostering scientific comparability across cases. This concise brief report aims to offer radiologists valuable insights into the PVA technique and considerations for post-PVA care and foster effective interdisciplinary collaboration.

Future liver remnant volume is associated with postoperative fentanyl consumption following open donor hepatectomy: a retrospective multivariate analysis

PURPOSE

Liver resection has a risk of postoperative hepatic dysfunction, including drug metabolism. Since fentanyl is primarily metabolized in the liver, liver resection requires exercising caution against fentanyl overdose in postoperative analgesia. The rationale for dose adjustment of fentanyl in the preoperative prescription for patients undergoing liver resection remains unclear. We examined whether postoperative fentanyl consumption is associated with the future liver remnant after liver resection and investigated factors influencing fentanyl consumption.

METHODS

In this retrospective study, 89 living liver donors undergoing open liver resection received intravenous patient-controlled analgesia with fentanyl 2 mg with thoracic epidural analgesia. The primary outcome was postoperative hourly consumption of intravenous patient-controlled analgesia with fentanyl. Future liver remnant volume (ml) and the ratio of future liver remnant volume to whole liver volume (%) were estimated by computed tomography volumetry and compared to determine which correlated more strongly with fentanyl hourly consumption. Multivariable analysis identified independent factors affecting fentanyl consumption, with adjustments for patient characteristics and intravenous patient-controlled analgesia setting.

RESULTS

Future liver remnant volume (ml) was significantly correlated more strongly than the ratio of future liver remnant (%) with postoperative fentanyl consumption (r = 0.53 vs. 0.36, p < 0.001). Larger future liver remnant volume (β = 0.25, p = 0.006) and age < 45 years (β = 0.24, p = 0.009) were independently associated with higher fentanyl consumption, while sex and weight were not.

CONCLUSIONS

Future liver remnant volume was significantly associated with postoperative fentanyl consumption. Smaller remnant liver volume and older age (≥ 45 years) were independent factors reducing postoperative fentanyl consumption in patients undergoing open donor hepatectomy.

Portocaval shunt can optimize transhepatic flow following extended hepatectomy: a short-term study in a porcine model

The aim of this study was to evaluate whether the portocaval shunt (PCS) corrects these unwanted changes in transhepatic flow after extended hepatectomy (EH). Forty female Landrace pigs were divided into two main groups: (A) EH (75%) and (B) no EH. Group A was divided into 3 subgroups: (A1) EH without PCS; (A2) EH with side-to-side PCS; and (A3) EH with end-to-side PCS. Group B was divided into 2 subgroups: (B1) side-to-side PCS and (B2) end-to-side PCS. HAF, PVF, and PVP were measured in each animal before and after the surgical procedure. EH increased the PVF/100 g (173%, p < 0.001) and PVP (68%, p < 0.001) but reduced the HAF/100 g (22%, p = 0.819). Following EH, side-to-side PCS reduced the increased PVF (78%, p < 0.001) and PVP (38%, p = 0.001). Without EH, side-to-side PCS reduced the PVF/100 g (68%, p < 0.001) and PVP (12%, p = 0.237). PVP was reduced by end-to-side PCS following EH by 48% (p < 0.001) and without EH by 21% (p = 0.075). PCS can decrease and correct the elevated PVP and PVF/100 g after EH to close to the normal values prior to resection. The decreased HAF/100 g in the remnant liver following EH is increased and corrected through PCS.

Effect of liver resection-induced increases in hepatic venous pressure gradient on development of postoperative acute kidney injury

BACKGROUND

The impact of changes in portal pressure before and after liver resection (defined as ΔHVPG) on postoperative kidney function remains unknown. Therefore, we investigated the effect of ΔHVPG on (i) the incidence of postoperative AKI and (ii) the renin-angiotensin system (RAAS) and sympathetic nervous system (SNS) activity.

METHODS

We included 30 patients undergoing partial liver resection. Our primary outcome was postoperative AKI according to KDIGO criteria. For our secondary outcome we assessed the plasma renin, aldosterone, noradrenaline, adrenaline, dopamine and vasopressin concentrations prior and 2 h after induction of anaesthesia, on the first and fifth postoperative day. HVPG was measured prior and immediately after liver resection.

RESULTS

ΔHVPG could be measured in 21 patients with 12 patients HVPG showing increases in HVPG (∆HVPG≥1 mmHg) while 9 patients remained stable. AKI developed in 7/12 of patients with increasing HVPG, but only in 2/9 of patients with stable ΔHVPG (p = 0.302). Noradrenalin levels were significantly higher in patients with increasing ΔHVPG than in patients with stable ΔHVPG. (p = 0.009). Biomarkers reflecting RAAS and SNS activity remained similar in patients with increasing vs. stable ΔHVPG.

CONCLUSIONS

Patients with increased HVPG had higher postoperative creatinine concentrations, however, the incidence of AKI was similar between patients with increased versus stable HVPG.

Intraoperative Increase of Portal Venous Pressure is an Immediate Predictor of Posthepatectomy Liver Failure After Major Hepatectomy: A Prospective Study

OBJECTIVES

The aim of this study was to assess intraoperative changes of hepatic macrohemodynamics and their association with ascites and posthepatectomy liver failure (PHLF) after major hepatectomy.

SUMMARY OF BACKGROUND DATA

Large-scale ascites and PHLF remain clinical challenges after major hepatectomy. No study has concomitantly evaluated arterial and venous liver macrohemodynamics in patients undergoing liver resection.

METHODS

Portal venous pressure (PVP), portal venous flow (PVF), and hepatic arterial flow (HAF) were measured intraoperatively pre- and postresection in 67 consecutive patients with major hepatectomy (ie, resection of ≥3 liver segments). A group of 30 patients with minor hepatectomy served as controls. Liver macrohemodynamics and their intraoperative changes (ie, Δ) were analyzed as predictive biomarkers of ascites and PHLF using Fisher exact, t test, or Wilcoxon rank sum test for univariate and logistic regression for multivariate analyses.

RESULTS

Major hepatectomy increased PVP by 26.9% (P = 0.001), markedly decreased HAF by 40.7% (P < 0.001), and slightly decreased PVF by 13.4% (P = 0.011). Minor resections had little effects on hepatic macrohemodynamics. There was no significant association of liver macrohemodynamics with ascites. While middle hepatic vein resection caused higher postresection PVP after right hepatectomy (P = 0.04), the Pringle maneuver was associated with a significant PVF (P = 0.03) and HAF reduction (P = 0.03). Uni- and multivariate analysis revealed an intraoperative PVP increase as an independent predictor of PHLF (P = 0.025).

CONCLUSION

Intraoperative PVP kinetics serve as independent predictive biomarker of PHLF after major hepatectomy. These data highlight the importance to assess intraoperative dynamics rather than the pre- and postresection PVP values.

The beneficial impacts of splanchnic vasoactive agents on hepatic functional recovery in massive hepatectomy porcine model

Background

Excessive portal pressure after massive hepatectomy can cause hepatic sinusoidal injury and have deleterious impacts on hepatic functional recovery, contributing to developing post-hepatectomy liver failure. This study aimed to assess the effects of splanchnic vasoactive agents on hepatic functional recovery and regeneration while clarifying the underlying mechanism, using a 70% hepatectomy porcine model.

Methods

Eighteen pigs undergoing 70% hepatectomy were involved in this study and divided into three groups: control (n=6), terlipressin (n=6), and octreotide (n=6). Terlipressin (0.5 mg) and octreotide (0.2 mg) were administered 3 times a day for each group with the first dose starting just before surgery until the 7th postoperative day, at which time the surviving pigs were sacrificed. During the period, portal pressure, liver weight, biochemical analysis, histological injury score, and molecular markers were evaluated and compared between groups.

Results

The 7-day survival rates in the octreotide, terlipressin, and control groups were 100%, 83.3%, and 66.7%, respectively. The portal pressures decreased in both terlipressin and octreotide groups than the control group at 30 minutes, 1 hour and 6 hours after hepatectomy. The amount of regeneration measured by liver weight to body weight ratio at the time of sacrifice in the terlipressin group was smaller than that in the control group (117% vs. 129%, P=0.03). Serum aspartate aminotransferase (AST) and total bilirubin levels at 1 and 6 hours after hepatectomy and prothrombin time/international normalized ratio (PT/INR) at 6 hours after hepatectomy were significantly improved in the terlipressin and octreotide groups compared to the control group. Serum endothelin-1 (ET-1) was significantly lower in the terlipressin group than that in the control group 6 hours after hepatectomy (P<0.01). The histological injury score in the control group was significantly higher than that in the terlipressin group on the 7th postoperative day (P<0.01).

Conclusions

Splanchnic vasoactive agents, such as terlipressin and octreotide, could effectively decrease portal pressure and attenuate liver injury after massive hepatectomy.

Portal vein arterialization as a salvage procedure in hepatopancreatobiliary surgery: a systematic review

Background

Portal vein arterialization (PVA) is a possible option when hepatic artery reconstruction is impossible during liver resection. The aim of this study was to review the literature on the clinical application of PVA in hepatopancreatobiliary (HPB) surgery.

Methods

We performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We systematically searched the PubMed, Embase and Web of Science databases until December 2019. Experimental (animal) studies, review articles and letters were excluded.

Results

Twenty studies involving 57 patients were included. Cholangiocarcinoma was the most common indication for surgery (40 patients [74%]). An end-to-side anastomosis between a celiac trunk branch and the portal vein was the main PVA technique (35 patients [59%]). Portal hypertension was the most common long-term complication (12 patients [21%] after a mean of 4.1 mo). The median follow-up period was 12 (range 1–87) months. The 1-, 3- and 5-year survival rates were 64%, 27% and 20%, respectively.

Conclusion

Portal vein arterialization can be considered as a rescue option to improve the outcome in patients with acute liver de-arterialization when arterial reconstruction is not possible. To prevent portal hypertension and liver injuries due to thrombosis or overarterialization, vessel calibre adjustment and timely closure of the anastomosis should be considered. Further prospective experimental and clinical studies are needed to investigate the potential of this procedure in patients whose liver is suddenly de-arterialized during HPB procedures.

Lipidomic signatures of post-hepatectomy liver failure using porcine hepatectomy models

Background

Clinical diagnosis of post-hepatectomy liver failure (PHLF) can only be made on or after the 5th postoperative day. Biomarker for early diagnosis is considered as a critical unmet need.

Methods

Twenty domestic female crossbreed (Yorkshire-landrace and duroc) pigs underwent sham operation (n=6), 70% (n=7) and 90% (n=7) partial hepatectomy (PH). A comprehensive lipidomic analysis was conducted using sera collected at pre-operation (PO), 14, 30, and 48 h after PH using nanoflow ultrahigh performance liquid chromatography-electrospray ionization-tandem mass spectrometry.

Results

Of the 184 quantified lipids, 14 lipids showed significant differences between the two resection groups starting at 30 h after surgery. Four phosphatidylcholine (PC) plasmalogen species (P-16:0/16:0, P-18:0/18:2, P-18:0/20:4, and P-18:0/22:6) and PC 32:2 significantly increased in the 90% PH group while these returned to PO level after 30 h in the 70% PH group, presumably implying the failure markers. In contrast, eight triacylglycerol (TG) species (40:0, 42:1, 42:0, 44:1, 44:2, 46:1, 46:2, and 48:3) and sphingomyelin d18:1/20:0 showed an opposite trend, wherein they significantly decreased in the 90% PH group while these in the 70% PH group were abruptly increased until 30 h but returned to near PO levels at 48 h, implying the recovery markers. Same trends could also be observed in the level of whole lipid classes of PC plasmalogens and TGs, in addition to selected individual lipid species.

Conclusions

Characteristic lipidomic signatures of PHLF could be identified using large animal models. These candidates have a potential to serve as a tool for early diagnosis and may open new paths to the study to overcome PHLF.

No alteration of Cyp3A4 activity after major hepatectomy in the early postoperative period - A prospective before-after study

BACKGROUND

The impact of major liver resection (LR) on the detoxifying function of the remaining liver tissue as represented by CYP3A activity has yet to be assessed. Therefore, this study evaluates the changes in CYP3A activity between preoperative values and after liver resection.

MATERIAL AND METHODS

To determine CYP3A activity, midazolam (MDZ) was used as a marker substance, 3 μg were applied intravenously one day before surgery and on the 3rd day after surgery. Subsequently blood was withdrawn at 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, 3, 4 and 6 h post application of the study drug. Plasma MDZ and 1-OH-MDZ concentration was assessed using a LC-MS/MS method. Volumetric analysis of the resected liver was done by syngo.CT liver analysis software (Siemens Healthineers) using preoperative multidetector computed tomography.

RESULTS

N = 13 (8 male/5 female) patients were included in this study and received preoperative evaluation, 11 patients were studied also after liver resection. The mean age was 62 (±15.3) years with a mean BMI of 23.6 ± 4.8 kg/m². No patient suffered from acute liver dysfunction postoperatively. None of the pharmacokinetic parameters assessed were significantly altered by liver resection. CYP3A activity over time was not significantly reduced by major liver resection.

CONCLUSION

This study gives first time data on the impact of major liver resection on CYP3A activity. It was shown that MDZ clearance representing in vivo CYP3A activity is not altered by major liver resection. This suggests no dose adjustment of commonly applied drugs which are CYP3A substrates needs to be carried out.

Modeling the hepatic arterial flow in living liver donor after left hepatectomy and postoperative boundary condition exploration

Preoperative and postoperative hepatic perfusion is modeled with one-dimensional (1-D) Navier-Stokes equations. Flow rates obtained from ultrasound (US) data and impedance resulted from structured trees are the inflow and outflow boundary condition (BC), respectively. Structured trees terminate at the size of the arterioles, which can enlarge their size after hepatectomy. In clinical studies, the resistance to pulsatile arterial flow caused by the microvascular bed can be reflected by the resistive index (RI), a frequently used index in assessing arterial resistance. This study uses the RI in a novel manner to conveniently obtain the postoperative outflow impedance from the preoperative impedance. The major emphasis of this study is to devise a model to capture the postoperative hepatic hemodynamics after left hepatectomy. To study this, we build a hepatic network model and analyze its behavior under four different outflow impedance: (a) the same as preoperative impedance; (b) evaluated using the RI and preoperative impedance; (c) computed from structured tree BC with increased radius of terminal vessels; and (d) evaluated using structured tree with both increased radius of root vessel, ie, the outlets of the postoperative hepatic artery, and increased radius of terminal vessels. Our results show that both impedance from (b) and (d) give a physiologically reasonable postoperative hepatic pressure range, while the RI in (b) allows for a fast approximation of postoperative impedance. Since hemodynamics after hepatectomy are not fully understood, the methods used in this study to explore postoperative outflow BC are informative for future models exploring hemodynamic effects of partial hepatectomy.

Evaluation of the role of transhepatic flow in postoperative outcomes following major hepatectomy (THEFLOW): study protocol for a single-centre, non-interventional cohort study

INTRODUCTION

Liver resection is the only curative treatment for primary and secondary hepatic tumours. Improvements in perioperative preparation of patients and new surgical developments have made complex liver resections possible. However, small for size and flow syndrome (SFSF) is still a challenging issue, rendering patients inoperable and causing postoperative morbidity and mortality. Although the role of transhepatic flow in the postoperative outcome has been shown in small partial liver transplantation and experimental studies of SFSF, this has never been studied in the clinical setting following liver resection. The aim of this study is to systematically evaluate transhepatic flow changes following major liver resection and its correlation with postoperative outcomes.

METHODS AND ANALYSIS

The TransHEpatic FLOW (THEFLOW) study is a single-centre, non-interventional cohort study, and aims to enrol 50 patients undergoing major hepatectomy (defined as hemihepatectomy or extended hepatectomy based on the Brisbane classification) with or without prior chemotherapy. The portal venous flow, hepatic artery flow and portal venous pressure are measured before and after each resection. All patients are followed-up for 3 months after the operation. During each evaluation, standard clinical data, posthepatectomy liver failure and overall morbidity and mortality will be recorded. THEFLOW study was initiated on 25 March 2018 and is expected to progress for 2 years.

ETHICS AND DISSEMINATION

This protocol study received approval from the Ethics Committee of the University of Heidelberg (registration number: S576/2017). The results of this study will be published in a peer-reviewed journal, and will also be presented at medical meetings.

TRIAL REGISTRATION NUMBER

NCT03762876.

Effect of Portal Venous Pressure on Liver Function of Donors in Living Donor Liver Transplantation

Background

We assessed the alterations in portal hemodynamics associated with donor right hepatectomy and its effects on functional regeneration of the remnant liver.

Material/Methods

This prospective study included 30 adult living donors who underwent right hepatectomy in the Liver Transplantation Unit, Faculty of Medicine, Cairo University from June 2015 to October 2016. During donor surgery, portal venous pressure (PVP) was measured using an antithrombotic catheter inserted into the main portal vein, and was measured before and after clamping of the right portal vein. Postoperatively, liver function tests were done daily until normalization. The outcome measures were the time to normalization of liver function tests and effect of residual volume and steatosis on PVP.

Results

All donors had normal PVP before clamping and changed significantly after clamping (p<0.001). After clamping, 25 donors (83%) had a PVP above 12 mmHg; i.e. had high portal pressure. The median percentage of change was 55%. There were obvious increases in liver enzymes and bilirubin after surgery, but albumin and international normalized ratio showed progressive decreases postoperatively. The percent change in PVP was positively correlated with the levels of liver enzymes, time to normalization of liver enzymes, albumin, and bilirubin, and with the degree of steatosis, bit it was negatively correlated with residual liver volume.

Conclusions

During living donor liver transplantation, PVP increases by over 50% after clamping of the right portal vein of the donor’s liver. This increase is associated with temporary delay of normalization of liver function of the donors.

Does acid-base equilibrium correlate with remnant liver volume during stepwise liver resection?

Small for size and flow syndrome (SFSF) is one of the most challenging complications following extended hepatectomy (EH). After EH, hepatic artery flow decreases and portal vein flow increases per 100 g of remnant liver volume (RLV). This causes hypoxia followed by metabolic acidosis. A correlation between acidosis and posthepatectomy liver failure has been postulated but not studied systematically in a large animal model or clinical setting. In our study, we performed stepwise liver resections on nine pigs to defined SFSF limits as follows: step 1: segment II/III resection, step 2: segment IV resection, step 3: segment V/VIII resection (RLV: 75, 50, and 25%, respectively). Blood gas values were measured before and after each step using four catheters inserted into the carotid artery, internal jugular vein, hepatic artery, and portal vein. The pH, [Formula: see text], and base excess (BE) decreased, but [Formula: see text] values increased after 75% resection in the portal and jugular veins. EH correlated with reduced BE in the hepatic artery. Pco₂ values increased after 75% resection in the jugular vein. In contrast, arterial Po₂ increased after every resection, whereas the venous Po₂ decreased slightly. There were differences in venous [Formula: see text], BE in the hepatic artery, and Pco₂ in the jugular vein after 75% liver resection. Because 75% resection is the limit for SFSF, these noninvasive blood evaluations may be used to predict SFSF. Further studies with long-term follow-up are required to validate this correlation.NEW & NOTEWORTHY This is the first study to evaluate acid-base parameters in major central and hepatic vessels during stepwise liver resection. The pH, [Formula: see text], and base excess (BE) decreased, but [Formula: see text] values increased after 75% resection in the portal and jugular veins. Extended hepatectomy correlated with reduced BE in the hepatic artery. Because 75% resection is the limit for small for size and flow syndrome (SFSF), postresection blood gas evaluations may be used to predict SFSF.

Establishing a Porcine Model of Small for Size Syndrome following Liver Resection

BACKGROUND

Small for size syndrome (SFSS) is responsible for a high proportion of mortalities and morbidities following extended liver resection.

AIM

The aim of this study was to establish a porcine model of SFSS.

METHODS

Twenty-four Landrace pigs underwent liver resection with a remnant liver volume of 50% (group A, n = 8), 25% (group B, n = 8), and 15% (group C, n = 8). After resection, the animals were followed up for 8 days and clinical, laboratory, and histopathological outcomes were evaluated.

RESULTS

The survival rate was significantly lower in group C compared with the other groups (p < 0.001). The international normalized ratio, bilirubin, aspartate transaminase, alanine transaminase, and alkaline phosphatase levels increased shortly after surgery in groups B and C, but no change was observed in group A (p < 0.05 for all analyses). The histopathological findings in group A were mainly mild mitoses, in group B severe mitoses and hepatocyte ballooning, moderate congestion, and hemorrhage, along with mild necrosis, and in group C extended tissue damage with severe necrosis, hemorrhage, and congestion.

CONCLUSIONS

Combination of clinical, laboratory, and histopathological evaluations is needed to confirm the diagnosis of SFSS. 75% liver resection in porcine model results in SFSS. 85% liver resection causes irreversible liver failure.