The prediction of portal pressure: a multivariate analysis of clinical data and intraoperative portal pressure

A systematic review of the impact of portal vein pressure changes on clinical outcomes following hepatic resection

BACKGROUND

There are evolving data correlating elevated post-hepatic resection portal vein pressure (PVP) with risk of developing post-resection liver failure (PLF) and other complications. As a consequence, modulation of PVP presents a potential strategy to improve outcomes following liver resection (LR). The primary aim of this study was to review the existing evidence regarding the impact of post-resection PVP on clinical outcomes in patients undergoing a LR.

METHODS

Systematic literature searches of electronic databases in accordance with PRISMA were conducted. Changes in PVP and clinical outcomes following liver resection were defined according to the existing literature.

RESULTS

Ten studies, consisting of 712 patients with a median age 61 (52-68) years, were identified that met the inclusion criteria. Of those, 77% (n = 550) underwent a major LR and 27% (n = 195) of patients had cirrhosis. Following LR, the median (range) PVP increased from 11.4 mmHg (median baseline, range 7.3-16.4) to 15.9 mmHg (7.9-19). The overall median incidence of PLF was 19%. Six of the ten studies found an elevated PVP after LR predicted PLF. One study found elevated PVP after LR predicted mortality after LR.

CONCLUSION

Elevated PVP following hepatic resection was associated with increased rates of PLF. It was not possible to define a specific threshold PVP for predicting PLF. Modulation of PVP therefore presents a potential strategy to mitigate the incidence of LR. Future studies should standardize on reporting liver remnant and haemodynamics to better characterize clinical outcomes following LR.

Portal Vein Pressure Change Predicts Posthepatectomy Liver Failure Following Right Lobectomy

The aim of this study was to evaluate the usefulness of intraoperative portal venous pressure (PVP) as a predictor of posthepatectomy liver failure (PHLF). Hepatic functional reserve is typically evaluated by using parameters such as albumin level, platelet count, prothrombin activity level, or indocyanine green retention rate at 15 minutes. Low hepatic functional reserve can enhance the risk of PHLF. We retrospectively analyzed the outcomes of 35 patients who underwent right lobectomy and intraoperative PVP measurements between April 2004 and August 2012. According to preoperative prediction scores, all patients were within a safe limit for right lobectomy. The patients were grouped into uncomplicated (n = 22) and PHLF (n = 13) groups by postoperative course. PHLF was defined as grade B or C according to International Study Group of Liver Surgery criteria. Patient background, intraoperative bleeding, operative time, and PVP elevation after hepatectomy (ΔPVP) grade were compared between the groups. No cases of in-hospital death occurred. Univariate analysis revealed significant differences in preoperative white blood counts, intraoperative bleeding, and ΔPVP between the groups (P < 0.05). The ΔPVP was an independent risk factor on multivariate analysis. A ΔPVP >3 cmH2O was associated with PHLF at 69.2% sensitivity and 90.9% specificity. Following right lobectomy, a ΔPVP >3 cmH2O indicates a risk of PHLF and warrants careful postoperative management.

A non-invasive magnetic resonance imaging-based model predicts portal venous pressure

OBJECTIVE

To establish a non-invasive model for the assessment of portal venous pressure (PVP) based on the magnetic resonance (MR) parameters.

METHODS

In this prospective study, contrast-enhanced magnetic resonance imaging (MRI) scan was performed in 109 patients indicated for upper abdominal surgeries after their written consents were obtained, and intraoperative PVP measurements were completed in 92 patients. Altogether 17 patients were excluded for not undergoing surgery or unsuccessful catheterization. A linear model was constructed for estimating PVP levels in 56 patients and further validation was conducted in the other 36 patients.

RESULTS

The PVP levels were significantly correlated with MR parameters, including splenic volume (SV), splenic venous diameter (SVD), liver/splenic volume ratio, portal venous diameter, hepatic diameter, portal venous cross-sectional area, ascites, varices and arterial portal shunts. A linear model was established as follows: PVP (mmHg) = 2.529 + 1.572 × SVD (mm) + 0.231 × SV/body mass index (× 10(4) cm(5) /kg) + 3.44 × aspartate aminotransferase-to-platelet ratio index. This model showed excellent accuracy in the detection of portal hypertension, with the area under the receiver operating characteristic curve (AUROC) of 0.945 (95% CI 0.867-1.000), with the sensitivity and specificity of 91.7% and 93.7%, respectively. The agreement analysis revealed that the predictive value using this formula closely reflected the patients' actual PVP level. Moreover, the validation confirmed the accuracy of this model for the assessment of portal hypertension [AUROC 0.935 (95% CI 0.856-1.000)].

CONCLUSIONS

The MRI-based formula has great potential for detecting portal hypertension. As a non-invasive measurement, it may be clinically accepted for the replacement of invasive modalities after further refinement.

Prediction of posthepatectomy hepatic functional reserve by serum hyaluronate

BACKGROUND

Serum hyaluronate can be used as an index of hepatic sinusoidal endothelial cell function and hepatic fibrosis. This study was designed to clarify the clinical significance of the serum hyaluronate level as a parameter of functional reserve.

METHODS

The study included 283 patients undergoing hepatectomy. Liver function parameters were examined before surgery and compared with outcomes. Patients were retrospectively grouped according to the presence or absence of postoperative hepatic dysfunction.

RESULTS

Preoperative serum hyaluronate levels were significantly raised in parallel with the degree of severity of the underlying chronic liver disease. Regression analysis revealed serum hyaluronate level to be an independent predictor of portal hypertension. In 131 patients undergoing major hepatectomy, preoperative hyaluronate levels were significantly higher in patients with poor outcome. Multivariable logistic regression analysis demonstrated serum hyaluronate and total bilirubin levels to be independent variables associated with postoperative hepatic dysfunction. Patients with high indocyanine green retention rate at 15 min (over 15 per cent) showed significantly higher morbidity and mortality rates when their serum hyaluronate levels were over 180 ng/ml.

CONCLUSION

Serum hyaluronate is a simple clinical marker for portal venous pressure and a reliable auxiliary parameter of hepatic functional reserve in combination with other liver function tests.

"Splenic artery steal syndrome" is a misnomer: the cause is portal hyperperfusion, not arterial siphon

Splenic artery embolization (SAE) improves hepatic artery (HA) flow in liver transplant (OLT) recipients with so-called splenic artery steal syndrome. We propose that SAE actually improves HA flow by reducing the HA buffer response (HABR). Patient 1: On postoperative day (POD) 1, Doppler ultrasonography (US) showed patent vasculature with HA resistive index (RI) of 0.8. On POD 4, aminotransferases rose dramatically; his RI was 1.0 with no diastolic flow. Octreotide was begun, but on POD 5 US showed reverse diastolic HA flow with no signal in distal HA branches. After SAE, US showed markedly improved flow, RI was 0.6, diastolic flow in the main artery, and complete visualization of all distal branches. By POD 6, liver function had normalized. RI in the main HA is 0.76 at 2 months postsurgery. Patient 2: On POD 1, RI was 1.0. US showed worsening intrahepatic signal, with no signal in the intrahepatic branches and reversed diastolic flow despite good graft function. On POD 7, SAE improved the intrahepatic waveform and RI (from 1.0 to 0.72). Patient 3: Intraoperative reverse diastolic arterial flow persisted on PODs 1, 2, and 3, with progressive loss of US signal in peripheral HA branches. SAE on POD 4 improved the RI (0.86) and peripheral arterial branch signals. Patient 4: US on POD 1 showed good HA flow with a normal RI (0.7). A sudden waveform change on POD 2 with increasing RI (0.83) prompted SAE, after which the wave form normalized, with reconstitution of a normal diastolic flow (RI 0.68). In conclusion, these reports confirm the usefulness of SAE for poor HA flow but suggest that inflow steal was not the problem. Rather than producing an increase in arterial inflow, SAE worked by reducing portal flow and HABR, thereby reducing end-organ outflow resistance. Evidence of this effect is the marked reduction of the RI after the SAE to 0.6, 0.72, 0.86, and 0.68, in patients 1-4, respectively. SAE reduces excessive portal vein flow and thereby ameliorates an overactive HABR that can cause graft dysfunction and ultimately HA thrombosis.

Jejunectomy can reduce excessively elevated portal pressure after major hepatectomy in beagle dogs

A number of factors can lead to the life-threatening liver dysfunction in the aftermath of an extended hepatectomy. Prominent among them is the high portal pressure induced by the concentrated flow of the entire stream of portal blood toward the small remnant liver. Twelve beagle dogs were randomly divided into group A (n=6, 70% hepatectomy) and group B (n=6, 70% hepatectomy after jejunectomy). Three dogs in each group were euthanized at 1 or 4 weeks after the operation and examined to evaluate hemodynamic changes, liver functions, and liver histology. One hour after the hepatectomy, the animals in group B exhibited a significantly lower portal pressure (P=0.002) and significantly higher hepatic arterial flow (P=0.004) than the animals in group A. As more time passed, the total hepatic flow and hepatic tissue flow both rose up to levels significantly higher than those in group A (P=0.037 and P=0.025, respectively). The alkaline phosphatase, total protein, albumin, and anti-thrombin III were all significantly better in group B than in group A on the 1st post-operative day. Liver specimens biopsied at 1 h after the hepatectomy showed significantly more swelling of the hepatocytes in group A than in group B. In addition, an immunohistochemical study using the TUNEL method for liver biopsy on the seventh post-operative day revealed numerous positive cells in group A but few in group B. Our results suggest that the portal pressure control by the enterectomy can forestall dysfunction of the remnant liver after extended hepatectomy, especially during the early post-operative period.