Patel, Mamta

Background and Aims: Hepatopulmonary syndrome (HPS) and a hyperdynamic circulation are common complications of advanced liver disease, but the relationship between HPS and cardiac index (CI) is poorly understood. We sought to compare CI in patients with and without HPS and to assess the relationship between CI and symptoms, quality of life, gas exchange, and exercise capacity among liver transplantation (LT) candidates. We performed a cross-sectional analysis within the Pulmonary Vascular Complications of Liver Disease 2 study, a multicenter prospective cohort study of patients being evaluated for LT. We excluded patients with obstructive or restrictive lung disease, intracardiac shunting, and portopulmonary hypertension. We included 214 patients (81 with HPS and 133 controls without HPS). Compared with controls, patients with HPS had a higher CI (least square mean 3.2 L/min/m2, 95% CI 3.1–3.4 vs. 2.8 L/min/m2, 95% CI 2.7–3.0, p < 0.001) after adjustment for age, sex, Model for End-stage Liver Disease-Sodium (MELD-Na) score and beta-blocker use, and a lower systemic vascular resistance. Among all LT candidates, CI was correlated with oxygenation (Alveolar-arterial oxygen gradient r=0.27, p< 0.001), intrapulmonary vasodilatation severity (p < 0.001), and biomarkers of angiogenesis. Higher CI was independently associated with dyspnea and worse functional class and physical quality of life after adjusting for age, sex, MELD-Na, beta-blocker use, and HPS status. HPS was associated with a higher CI among LT candidates. Independent of HPS, higher CI was associated with increased dyspnea and worse functional class, quality of life, and arterial oxygenation.

Background and Aims Portopulmonary hypertension (POPH) was previously associated with a single‐nucleotide polymorphism (SNP) rs7175922 in aromatase (cytochrome P450 family 19 subfamily A member 1 [CYP19A1]). We sought to determine whether genetic variants and metabolites in the estrogen signaling pathway are associated with POPH. Approach and Results We performed a multicenter case‐control study. POPH patients had mean pulmonary artery pressure >25 mm Hg, pulmonary vascular resistance >240 dyn‐sec/cm−5, and pulmonary artery wedge pressure ≤15 mm Hg without another cause of pulmonary hypertension. Controls had advanced liver disease, right ventricular (RV) systolic pressure <40 mm Hg, and normal RV function by echocardiography. We genotyped three SNPs in CYP19A1 and CYP1B1 using TaqMan and imputed SNPs in estrogen receptor 1 using genome‐wide markers. Estrogen metabolites were measured in blood and urine samples. There were 37 patients with POPH and 290 controls. Mean age was 57 years, and 36% were female. The risk allele A in rs7175922 (CYP19A1) was significantly associated with higher levels of estradiol (P = 0.02) and an increased risk of POPH (odds ratio [OR], 2.36; 95% confidence interval [CI], 1.12‐4.91; P = 0.02) whereas other SNPs were not. Lower urinary 2‐hydroxyestrogen/16‐α‐hydroxyestrone (OR per 1‐ln decrease = 2.04; 95% CI, 1.16‐3.57; P = 0.01), lower plasma levels of dehydroepiandrosterone‐sulfate (OR per 1‐ln decrease = 2.38; 95% CI, 1.56‐3.85; P < 0.001), and higher plasma levels of 16‐α‐hydroxyestradiol (OR per 1‐ln increase = 2.16; 95% CI, 1.61‐2.98; P < 0.001) were associated with POPH. Conclusions Genetic variation in aromatase and changes in estrogen metabolites were associated with POPH.

We investigated the prevalence of spirometric restriction in liver transplantation (LT) candidates and the clinical impacts of restriction. We performed a cross‐sectional study within the Pulmonary Vascular Complications of Liver Disease 2 (PVCLD2) study, a multicenter prospective cohort study of patients being evaluated for LT. Patients with obstructive lung disease or missing spirometry or chest imaging were excluded. Patients with and without restriction, defined as a forced vital capacity (FVC) <70% predicted, were compared. Restriction prevalence was 18.4% (63/343). Higher Model for End‐Stage Liver Disease–sodium score (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02‐1.11; P = 0.007), the presence of pleural effusions (OR, 3.59; 95% CI, 1.96‐6.58; P < 0.001), and a history of ascites (OR, 2.59; 95% CI, 1.26‐5.33; P = 0.01) were associated with the presence of restriction, though one‐third with restriction had neither pleural effusions nor ascites. In multivariate analysis, restriction was significantly and independently associated with lower 6‐minute walk distances (least squares mean, 342.0 [95% CI, 316.6‐367.4] m versus 395.7 [95% CI, 381.2‐410.2] m; P < 0.001), dyspnea (OR, 2.69; 95% CI, 1.46‐4.95; P = 0.002), and lower physical component summary Short Form 36 scores indicating worse quality of life (least squares mean, 34.1 [95% CI, 31.5‐36.7] versus 38.2 [95% CI, 36.6‐39.7]; P = 0.004). Lower FVC percent predicted was associated with an increased risk of death (hazard ratio, 1.16; 95% CI, 1.04‐1.27 per 10‐point decrease in FVC percent predicted; P = 0.01). Restriction and abnormal lung function are common in LT candidates; can be present in the absence of an obvious cause, such as pleural effusions or ascites; and is associated with worse exercise capacity, quality of life, and survival.

Screening for hepatopulmonary syndrome (HPS) using pulse oximetry is recommended in liver transplant (LT) candidates because mortality is increased, independently of the severity of the oxygenation defect. LT exception points may be afforded to those with HPS and severe hypoxemia. We assessed the screening characteristics of pulse oximetry for HPS. The Pulmonary Vascular Complications of Liver Disease 2 study is a multicenter, prospective cohort study of adults undergoing their first LT evaluation. Patients underwent protocolized assessment of oxygen saturation by pulse oximetry (SpO2), arterial blood gas, spirometry, and contrast‐enhanced echocardiography (CE). HPS was defined as an alveolar‐arterial gradient ≥15 mm Hg (≥20 mm Hg if age >64 years), intrapulmonary vascular dilatation on CE, and absence of lung disease. The study sample included 363 patients. Of these, 75 (20.7%; 95% confidence interval [CI], 16.6%‐25.2%) met the criteria for HPS. The area under the receiver operating characteristic curve (or c‐statistic) for SpO2 in discriminating HPS was 0.59 (95% CI, 0.51‐0.66). An SpO2 <96%, recommended by practice guidelines as a threshold to require further testing, had low sensitivity (28%; 95% CI, 18%‐28%). The c‐statistic of SpO2 in discriminating HPS with a partial pressure of oxygen (PaO2) <60 mm Hg (eligible for LT exception points) was 0.76 (95% CI, 0.46‐1.00). An SpO2 cutoff of <96% had higher sensitivity for detecting HPS with PaO2 <60 mm Hg (71%; 95% CI, 38%‐100%) but was still inadequate. Conclusion: Pulse oximetry is not sufficiently sensitive to screen for HPS in LT candidates. Arterial blood gas and CE are required in LT candidates for diagnosis of HPS.