Portopulmonary Hypertension and Liver Transplantation: Hemodynamic Consequences at Reperfusion

Keeping Patients with End-Stage Liver Disease Alive While Awaiting Transplant: Management of Complications of Portal Hypertension

Complications of portal hypertension such as gastroesophageal variceal hemorrhage, ascites, and spontaneous bacterial peritonitis, as well as pulmonary complications, are often responsible for diminished quality of life, excess morbidity and mortality, increased health care resource use and expenditure, and dropout from the liver transplant (LT) waiting list. Therefore, the care of LT candidates on the waiting list must be centered on anticipation and prompt intervention for these complications.

Immediate postoperative management and complications on the intensive care unit

The postoperative management of patients immediately after liver transplantation requires knowledge of this complex surgery and the physiology that accompanies liver failure. A multidisciplinary approach to the care of these patients is essential in order to reduce postoperative complications and preserve function in the transplanted organ. By their nature, patients undergoing liver transplantation have complicated medical problems before surgery which must be borne in mind when managing them after surgery. Haemorrhage, haemodynamic instability, acute renal failure, hepatic artery thrombosis and primary graft non-function are some of the complications that clinicians must be prepared for in the first days after transplantation. Pre-empting complications and acting rapidly to overt them is likely to have a considerable positive impact in these patients.

Long-term outcome in liver transplantation candidates with portopulmonary hypertension

Portopulmonary hypertension (PoPH) is diagnosed in 2-6% of liver transplantation (LT) candidates. We studied outcomes of candidates for LT suffering from PoPH. Data were collected retrospectively from a prospective registry. Pulmonary hemodynamic variables were collected at the time of PoPH diagnosis, at last evaluation before LT, and within 6 months and beyond 6 months after LT. Forty-nine patients (35 males, 48 ± 8 years) were analyzed (median Model for End-Stage Liver Disease score 20). At baseline, mean pulmonary artery pressure (mPAP) was 44 ± 10 mm Hg (range 26-73 mm Hg), cardiac index was 3.5 ± 0.9 L/min/m² , and pulmonary vascular resistance was 5.6 ± 2.8 Wood units. Hemodynamic reassessment performed in 35 patients who were treated with pulmonary arterial hypertension-targeted therapies before LT resulted in significant decreases in both mPAP (36 ± 7 versus 47 ± 10 mm Hg, P < 0.0001) and pulmonary vascular resistance (3.0 ± 1.4 versus 6.1 ± 3.1 Wood units, P < 0.0001). Fourteen patients (29%) died without having had access to LT. Thirty-five patients underwent LT and were followed up for a median of 38 months. Eight patients (23%) died after LT including 5 due to PoPH (after 1 day to 6 months). Among survivors (n = 27), all patients treated with intravenous epoprostenol were weaned off post-LT, and endothelin receptor antagonist or phosphodiesterase type 5 inhibitors were continued in 15/27 patients (55%). At last evaluation, 20/27 patients (74%) had mPAP <35 mm Hg and 8 of them (30%) had mPAP <25 mm Hg. Overall survival estimates after LT were 80%, 77%, and 77% at 6 months, 1 year, and 3 years, respectively.

CONCLUSION

Stabilization or reversibility of PoPH seems to be an attainable goal using the combination of pulmonary arterial hypertension-targeted therapies and LT in patients who are transplantation candidates. (Hepatology 2017;65:1683-1692).

Hepatopulmonary syndrome and portopulmonary hypertension

Hepatopulmonary syndrome and portopulmonary hypertension are 2 of many diseases that affect the lungs in patients with liver disease. The 2 vascular conditions are often confused. We review both hepatopulmonary syndrome and portopulmonary hypertension to better understand their pathophysiologies, clinical presentations, tools to aid in differentiating and diagnosing the disease states, treatment options, and influences on patient prognosis. We also consider patient viability for liver transplantation.

The impact of portopulmonary hypertension on intraoperative right ventricular function of living donor liver transplant recipients

BACKGROUND

Portopulmonary hypertension (PPH) burdens a right ventricle (RV) already exposed to physiologic stress during liver transplantation. The magnitude of the impact of PPH on RV function, especially early reperfusion, has not been evaluated adequately by prospective controlled trials. In this study, we prospectively quantified the impact of PPH on the RV function in living donor liver transplant recipients.

METHODS

Twenty patients undergoing living donor liver transplant were stratified based on mean pulmonary artery pressure (mPAP) into a control group (mPAP <25 mm Hg) and a PPH group (mPAP ≥25 mm Hg). Standard anesthetic technique and monitoring were used. Fiberoptic pulmonary artery catheters enabled to measure RV ejection fraction (RVEF) were used. Hemodynamics were recorded after induction of anesthesia, the end of hepatectomy, before portal unclamping, 5 and 30 minutes after reperfusion, and at skin closure.

RESULTS

The PPH group had significantly lower RVEF, stroke volume, and higher central venous pressure and RV end-diastolic volume index after portal unclamping versus the controls. Pulmonary vascular resistance index and mPAP were significantly higher throughout the operation in the PPH group, but RV stroke work index did not differ significantly between groups. RVEF was significantly reduced in the PPH group after reperfusion compared with baseline, but the control group did not experience such a reduction.

CONCLUSIONS

Mild to moderate PPH was associated with reduced RVEF during liver transplantation, especially after reperfusion, likely because of a reduced RV contractile reserve in PPH patients. This reduction in RVEF was clinically well tolerated by patients with mild to moderate PPH.

Postoperative Care of the Liver-Transplant Patient

Liver transplantation (LT) is performed to improve life expectancy and quality of life in patients with advanced chronic liver disease (CLD), and to save life in the context of acute liver failure (ALF). These two groups of patients differ significantly in terms of mean age, prior comorbidity, and degree of extra-hepatic organ dysfunction, requiring substantially different approaches to supportive care. Common aspects of care are those directed at the transplanted organ itself, with regard to monitoring and recognition of early dysfunction, initiation of immunosuppression, and management of surgical complications. Close liaison with the multidisciplinary team, which will include the intensivist, transplant surgeon, transplant hepatologist, anesthesiologist, and radiologist, is required.

Portopulmonary hypertension

It has been widely accepted that development of porto-pulmonary hypertension (POPH) is independent of the cause of portal hypertension. The degree of hepatic damage and liver function do not correlate with predisposition to POPH or its severity. However, portal hypertension has been confirmed as a prerequisite for developing pulmonary hypertension. Transthoracic echocardiography is the best screening test for the presence of POPH, but a diagnosis of POPH can be established only by right heart catheterization. Randomized controlled trials comparing the efficacy and safety of different pharmacologic strategies are lacking in patients with POPH. The general management includes diuretics and oxygen supplementation. Notably, moderate to severe POPH predisposes candidates for orthotopic liver transplantation to a higher risk of perioperative mortality. Vasomodulating pharmacologic agents are used in patients with moderate to severe POPH to decrease pulmonary arterial hypertension, thereby permitting liver transplantation to be performed safely. Epo-prostenol is the best-studied medication, and bosentan appears promising.

Assessment of acute pulmonary vascular reactivity in portopulmonary hypertension

The role of acute pulmonary vasodilator testing in portopulmonary hypertension (PoPH), a current contraindication for orthotopic liver transplantation (OLT), has not been thoroughly elucidated. The purpose of this work was to analyze the results of acute vasodilator testing with inhaled nitric oxide (NO), to compare them with intravenous epoprostenol (PGI(2)), and to investigate the acute effects of the oral vasodilator isosorbide-5-mononitrate (Is-5-MN), in patients with PoPH. A total of 19 patients with PoPH (male/female = 9/10) were studied. Pulmonary hemodynamic measurements were performed at baseline and during NO inhalation (40 ppm); additionally, 15 patients were tested with PGI(2) (2-12 mug/kg/minute) and 8 were tested with Is-5-MN (20-40 mg). Inhaled NO reduced pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) by 5.7% and 11.0%, respectively. PGI(2) elicited greater reductions in PAP (11.8%) and PVR (-24.0%), and produced a 28% drop in systemic vascular resistance (SVR) and a 17% increase in the cardiac index (CI). Is-5-MN reduced PAP by 25.6% and PVR by 21.5%, without systemic changes. There was good agreement between the response to PGI(2) and Is-5-MN: 6 patients of the whole series (32%) decreased PAP >20% from baseline, reaching a final value < or = 35 mmHg, the current limit for OLT. In conclusion, acute vasodilator testing has a relevant role in PoPH, as it identifies one-third of patients able to reach a more favorable hemodynamic situation, which can be determinant for their management. For vasodilator testing, PGI(2) is more suitable than NO in PoPH. Is-5-MN exerts a selective effect on pulmonary circulation in patients who had already responded to PGI(2).

Hepatopulmonary syndrome and portopulmonary hypertension

The incidence of pulmonary vascular disorders is significantly increased in patients with liver disease. Intrapulmonary shunting with hypoxemia in patients with liver disease is diagnosed as hepatopulmonary syndrome (HPS), whereas precapillary pulmonary vessel obliteration is identified as portopulmonary hypertension (PPHTN). Because the symptoms of liver disease can mimic those of pulmonary vascular disease, all patients with hepatic failure should be screened for these two diseases. Pulse oximetry effectively screens for hypoxemia associated with HPS, whereas an elevated right ventricular systolic pressure estimated by echocardiography identifies patients at risk of having PPHTN. Liver transplantation is the only effective medical therapy for HPS. However, those who have a resting arterial oxygenation less than 50 mm Hg or a shunt measured by scintigraphic perfusion greater than 20% have an unacceptably high mortality rate following surgery. Compared with HPS, there are more therapeutic options that can bridge patients with PPHTN to transplantation. Drugs used to manage idiopathic pulmonary hypertension have shown promise in the treatment of PPHTN. Prostanoids, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors have improved transplant survival. Despite treatment, however, perioperative mortality for patients with PPHTN remains high. Even with successful transplantation, HPS and PPHTN can persist or develop de novo. Long-term follow-up and surveillance of liver transplant recipients is thus indicated to identify HPS and PPHTN following surgery.