Hepatopulmonary syndrome: more than just a matter of tone?

Inhaled nitric oxide improves the hepatopulmonary syndrome: a physiologic analysis

The hepatopulmonary syndrome (HPS) is defined by liver dysfunction, intrapulmonary vasodilatation and abnormal oxygenation. Hypoxaemia is progressive and liver transplant is the only effective treatment. Severe hypoxaemia is a life-threatening HPS complication, particularly after transplant. We evaluated gas-exchange and haemodynamic effects of invasive therapies in a consecutive sample of 26 pre-transplant patients. Inhaled nitric oxide significantly improved partial pressure of oxygen (12.4 mm Hg; p=0.001) without deleterious effects on cardiac output. Trendelenburg positioning resulted in a small improvement, and methylene blue did not, though individual responses were variable. Future studies should prospectively evaluate these strategies in severe post-transplant hypoxaemia.

Role of splenic reservoir monocytes in pulmonary vascular monocyte accumulation in experimental hepatopulmonary syndrome

BACKGROUND AND AIM

Pulmonary monocyte infiltration plays a significant role in the development of angiogenesis in experimental hepatopulmonary syndrome (HPS) after common bile duct ligation (CBDL). Hepatic monocytes are also increased after CBDL, but the origins remain unclear. Splenic reservoir monocytes have been identified as a major source of monocytes that accumulate in injured tissues. Whether splenic monocytes contribute to monocyte alterations after CBDL is unknown. This study evaluates monocyte distributions and assesses effects of splenectomy on monocyte levels and pulmonary vascular and hepatic abnormalities in experimental HPS.

METHODS

Splenectomy was performed in CBDL animals. Monocyte levels in different tissues and circulation were assessed with CD68. Pulmonary alterations of HPS were evaluated with vascular endothelial growth factor-A (VEGF-A) levels, angiogenesis, and alveolar-arterial oxygen gradient (AaPO₂ ). Liver abnormalities were evaluated with fibrosis (Sirius red), bile duct proliferation (CK-19), and enzymatic changes.

RESULTS

Monocyte levels increased in the lung and liver after CBDL and were accompanied by elevated circulating monocyte numbers. Splenectomy significantly decreased monocyte accumulation, VEGF-A levels, and angiogenesis in CBDL animal lung and improved AaPO₂ levels. In contrast, hepatic monocyte levels, fibrosis, and functional abnormalities were further exacerbated by spleen removal.

CONCLUSIONS

Splenic reservoir monocytes are a major source for lung monocyte accumulation after CBDL, and spleen removal attenuates the development of experimental HPS. Liver monocytes may have different origins, and accumulation is exacerbated after depletion of splenic reservoir monocytes. Tissue specific monocyte alterations, influenced by the spleen reservoir, have a significant impact on pulmonary complications of liver disease.

Proposed management algorithm for severe hypoxemia after liver transplantation in the hepatopulmonary syndrome

The hepatopulmonary syndrome (HPS) is defined as the triad of liver disease, intrapulmonary vascular dilatation, and abnormal gas exchange, and is found in 10-32% of patients with liver disease. Liver transplantation is the only known cure for HPS, but patients can develop severe posttransplant hypoxemia, defined as a need for 100% inspired oxygen to maintain a saturation of ≥85%. This complication is seen in 6-21% of patients and carries a 45% mortality. Its management requires the application of specific strategies targeting the underlying physiologic abnormalities in HPS, but awareness of these strategies and knowledge on their optimal use is limited. We reviewed existing literature to identify strategies that can be used for this complication, and developed a clinical management algorithm based on best evidence and expert opinion. Evidence was limited to case reports and case series, and we determined which treatments to include in the algorithm and their recommended sequence based on their relative likelihood of success, invasiveness, and risk. Recommended therapies include: Trendelenburg positioning, inhaled epoprostenol or nitric oxide, methylene blue, embolization of abnormal pulmonary vessels, and extracorporeal life support. Availability and use of this pragmatic algorithm may improve management of this complication, and will benefit from prospective validation.

Defining and characterizing severe hypoxemia after liver transplantation in hepatopulmonary syndrome

Hepatopulmonary syndrome is defined as a triad of liver disease, intrapulmonary vascular dilatations, and abnormal gas exchange, and it carries a poor prognosis. Liver transplantation is the only known cure for this syndrome. Severe hypoxemia in the early postoperative period has been reported to be a major complication and often leads to death in this population, but it has been poorly characterized. We sought to propose an objective definition for this complication and to describe its risk factors, incidence, and outcomes. We performed a systematic literature search and reviewed our single-center experience to characterize this complication. On the basis of the most commonly applied definition in 27 identified studies, we objectively defined severe postoperative hypoxemia as hypoxemia requiring a 100% fraction of inhaled oxygen to maintain a saturation ≥ 85% and out of proportion to any concurrent lung process. Nineteen of the 27 reports (70%) fulfilled this definition, as did 4 of the 21 patients (19%) at our center. We determined the prevalence and mortality of this complication from reports including 10 or more consecutive patients and providing sufficient postoperative details to determine whether this complication had occurred. In these reports, the prevalence of this complication was 12% (25/209). For the 11 cases with reported outcomes, the posttransplant mortality rate was 45% (5/11). There was a trend toward an increased risk of developing this complication in patients with very severe preoperative hypoxemia, defined as a partial pressure of arterial oxygen ≤ 50 mm Hg (8/41 with very severe hypoxemia versus 3/49 without severe hypoxemia, P = 0.053), and there was a significantly increased risk for patients with anatomic shunting ≥ 20% (7/25 with anatomic shunting ≥ 20% versus 1/25 without anatomic shunting ≥ 20%, P = 0.049). In conclusion, increased preoperative vigilance for this common complication is required among high-risk patients, and further research is required to identify the best management strategies.

Unexplained cyanosis revealing hepatopulmonary syndrome in a child with asymptomatic congenital hepatic fibrosis: a case report

Introduction

Hepatopulmonary syndrome is a rare disease that affects patients of any age with acute or chronic liver disease. Liver transplantation is the only therapeutic option of proved benefit, and can result in substantial improvement or total improvement in postoperative gas exchange abnormalities.

Case presentation

We report the case of a cyanotic 13-year-old Pakistani boy whose chest computed tomography scan showed normal lung fields and mediastinum with incidental findings of a prominent liver surface with a collateral vein connecting a portal cavernoma to the dilated terminal inferior vena cava. Sonography of his abdomen along with a portal venous Doppler study showed multiple collateral veins replacing the portal vein. A liver biopsy revealed congenital hepatic fibrosis. Contrast-enhanced echocardiography with agitated saline and a 99m Technetium-macroaggregated albumin perfusion lung scan confirmed intrapulmonary shunting. The patient underwent a successful liver transplantation that resulted in improved gas exchange.

Conclusions

Hepatopulmonary syndrome should be included in the differential diagnosis of unexplained hypoxemia with an evaluation of possible portal hypertension or liver disease even in the absence of other clinical symptoms.

Norfloxacin therapy for hepatopulmonary syndrome: a pilot randomized controlled trial

BACKGROUND & AIMS

The hepatopulmonary syndrome occurs in up to one-third of patients with cirrhosis. Animal models of this disease suggest that endotoxemia might cause nitric oxide-mediated vascular dilatation that can be inhibited by the antibiotic norfloxacin. We sought to test this hypothesis in humans.

METHODS

We conducted a pilot randomized, controlled crossover trial of norfloxacin 400 mg twice daily for 4 weeks with a 4-week washout period to assess the feasibility of a larger trial. The primary clinical end point was change in alveolar-arterial oxygen gradient (AaDO₂).

RESULTS

Recruitment was challenging, and change in AaDO₂ was highly variable. We recruited 9 adults (1 woman; age, 60 ± 9 years; AaDO₂, 50 ± 22 mm Hg). AaDO₂ decreased by 0.8 ± 4.8 and 3.4 ± 12.4 mm Hg while on norfloxacin and placebo, respectively (P = .59).

CONCLUSIONS

Recruitment difficulties and variability of the primary outcome measure suggest the need for a multicenter clinical research network for future therapeutic trials in this disease. There was no major effect of norfloxacin on gas exchange in patients with hepatopulmonary syndrome.

Respiratory failure and hypoxemia in the cirrhotic patient including hepatopulmonary syndrome

PURPOSE OF REVIEW

Liver cirrhosis and portal hypertension present with three unique pulmonary complications that are the subject of ongoing clinical research: hepatopulmonary syndrome, portopulmonary hypertension (POPH), and hepatic hydrothorax. The present article is based on a review of the current literature on how to manage these disorders, which are highly important to both anesthesiologists and intensive care physicians.

RECENT FINDINGS

Hepatopulmonary syndrome leads to progressive hypoxemia through diffuse vasodilatation of the pulmonary microcirculation. Liver transplantation, although associated with increased mortality, is the only viable treatment. POPH occurs when vascular remodeling triggers an increase in pulmonary artery pressure and resistance. The role of liver transplantation in POPH is controversial given the excessive mortality in patients with moderate to severe POPH. Medical treatment is able to decrease pulmonary artery pressures, though multicenter randomized controlled trials showing improved outcome are lacking to date. Ultrasound plays an increasingly important role in the diagnosis of all three conditions.

SUMMARY

Patients with end-stage liver disease are at risk for respiratory failure and hypoxemia and need to be screened for hepatopulmonary syndrome, POPH, and hepatic hydrothorax. Failure to timely recognize and adequately treat these complications of cirrhosis may have severe consequences.

Relationship between liver cirrhosis and pulmonary function impairment

AIM: To determine the relationship between liver cirrhosis and pulmonary function impairment.

METHODS: Fifty patients with liver cirrhosis, who were treated at our hospital and the First Affiliated Hospital of Sun Yat-Sen University from May 2007 to March 2008, were included in the study. All patients underwent pulmonary function tests (PFTs) to assess forced expiratory volume in one second (FEV₁), FEV₁/FVC (forced vital capacity), single-breath carbon monoxide diffusing capacity (DLCO) and DLCO per unit of alveolar volume (KCO, also known as DLCO/VA). The mean FEV1, FEV1/FVC, DLCO and KCO were compared between patients with and without liver palm, spider naevi, clinical jaundice, hypoproteinemia, hypersplenism or widening of the portal vein, respectively.

RESULTS: Approximately 34 percent of patients presented with ventilation abnormalities, mainly restrictive ventilation disorders. Decreased diffusion capacity was the most common pulmonary function disorder and was found in 72% of patients. The Child-Pugh score was correlated inversely with KCO (r = -0.351, P < 0.05). Serum albumin level was correlated positively with FEV₁ and KCO (r = 0.334 and 0.336, respectively; both P < 0.05). The width of the portal vein was correlated inversely with FEV₁ and DLCO (r = -0.389 and -0.417, respectively; both P < 0.05). The thickness of the spleen was correlated inversely with DLCO and KCO (r = -0.644 and -0.536, respectively; both P < 0.01). Hemoglobin concentration and the thickness of the spleen were independent predictors of DLCO (P < 0.05).

CONCLUSION: The impairment of diffusion capacity is a very common disorder in patients with liver cirrhosis. Long-term portal hypertension is closely associated with the development of impaired diffusion capacity in patients with liver cirrhosis.

Safety and efficacy of combined use of sildenafil, bosentan, and iloprost before and after liver transplantation in severe portopulmonary hypertension

Portopulmonary hypertension (PPHTN) represents a constrictive pulmonary vasculopathy in patients with portal hypertension. Liver transplantation (LT) may be curative and is usually restricted to patients with mild-to-moderate disease severity characterized by a mean pulmonary artery pressure (mPAP < 35 mm Hg). Patients with severe disease (mPAP > 50 mm Hg) are usually excluded from transplantation. We describe a patient with severe PPHTN, initiated on sequential and ultimately combination therapy of prostacyclin, sildenafil, and bosentan (PSB) pretransplantation and continued for 2 years posttransplantation. Peak mPAP on PSB therapy was dramatically reduced from 70 mm Hg to 32 mm Hg pretransplantation, and continued therapy facilitated a further fall in mPAP to 28 mm Hg posttransplantation. The pulmonary vascular resistance index fell from 604 to 291 dyne second(-1) cm(-5). The perioperative mPAP rose to 100 mm Hg following an episode of sepsis and fell with optimization of PSB therapy. In conclusion, this is the first reported patient with severe PPHTN using this combination of vasodilator therapy as a bridge to LT and then as maintenance in the posttransplantation phase. This regimen may enable LT in similar patients in the future, without long-term consequences.

Pulmonary vascular abnormalities in cirrhosis

Two pulmonary vascular disorders can occur in liver disease and/or portal hypertension: the hepatopulmonary syndrome (HPS), which is characterized by intrapulmonary vascular dilatations, and portopulmonary hypertension (POPH), in which pulmonary vascular resistance is elevated. POPH and HPS are characterized by distinct pulmonary microvascular remodelling, which occurs at different anatomical sites of the pulmonary microcirculation. The exact pathophysiological mechanisms of these pulmonary vascular disorders are unknown. However, as HPS and POPH have been reported in patients with extrahepatic portal hypertension, the factor that determines their development must be portal hypertension. The clinical presentations are very different, with gas exchange impairment in HPS and hemodynamic failure in POPH. The severity of HPS seems to parallel the severity of liver failure, whereas no simple relationship has been identified between hepatic impairment and the severity of POPH. Resolution of HPS is common after liver transplantation, which has an uncertain effect in POPH.