Pulmonary Aspects of Liver Disease and Liver Transplantation

The hepatopulmonary syndrome: new name, old complexities

On the basis of previous work, our own experience and findings, and the considerations discussed above, we propose a set of four diagnostic criteria for the hepatopulmonary syndrome: 1. presence of chronic hepatic disease (alcoholic, postnecrotic, or primary biliary cirrhosis or active chronic hepatitis)--severe liver dysfunction may not be mandatory; 2. absence of intrinsic cardiopulmonary disease, with normal chest radiograph or with nodular basal shadowing; 3. pulmonary gas exchange abnormalities--an increased alveolar-arterial oxygen gradient (> or = 2.0 kPa) with or without hypoxaemia; 4. the extrapulmonary appearance of intravenous radiolabelled microspheres or a positive contrast enhanced echocardiogram, suggesting intrapulmonary vascular abnormalities. Although these four criteria appear straightforward, there may be other features that are not always present--namely: 1. low transfer factor (diffusing capacity); 2. shortness of breath, with or without platypnoea and orthodeoxia; 3. increased cardiac output and reduced pulmonary vascular pressures; 4. small (or no) increase in pulmonary vascular resistance when the patient is breathing low oxygen mixtures. From the physiological viewpoint, the hepatopulmonary syndrome provides an excellent model for clinical research in the pathophysiology of pulmonary gas exchange. So far it has been possible to show that arterial hypoxaemia in this condition is (1) partitioned into components resulting from VA/Q mismatching, intrapulmonary shunt, and limitations of oxygen diffusion; (2) modulated by the interplay between the intrapulmonary and the extrapulmonary determinants of PaO2, such as cardiac output and minute ventilation; (3) vulnerable to the influence of inadequate pulmonary vascular tone; and (4) resolved when the injured liver is replaced and hepatic function is restored to within normal limits.

A prospective study of pulmonary function and gas exchange following liver transplantation

Pulmonary function and gas exchange were prospectively studied in 95 patients before and 9 to 15 months following liver transplantation. Pretransplant, the most common PF abnormality was impaired efficiency of gas exchange as measured by Dss. As a group, the mean Dss was 78.0 +/- 16.6 percent predicted and was found to be less than 80 percent predicted in 50 patients. As a group, patients with the most severe liver diseases clinically (Child's C classification) had the lowest mean Dss pretransplant. Posttransplant, three findings were of clinical importance: PaCO2 significantly improved posttransplantation, suggesting a resolution of pretransplant respiratory alkalosis. Expiratory airflow obstruction, measured by a change in the FEV1/FVC, was extremely uncommon posttransplant. Mean Dss improved significantly in patients with Child's C severity of liver disease. The most frequent deteriorations in Dss statistically were associated with posttransplant thoracotomy, ARDS, nonspecific pneumonitis, significant pleural effusions and hepatic retransplantation.

Frequency and significance of intrapulmonary right-to-left shunting in end-stage hepatic disease

Intrapulmonary vascular abnormalities consisting of arteriovenous malformations and capillary dilatations have been described in patients with severe liver disease. These intrapulmonary vascular abnormalities can result in intrapulmonary right-to-left shunting and hypoxemia. Twenty-five of 53 patients (47%) with end-stage hepatic disease were found to have contrast echocardiographic evidence of intrapulmonary right-to-left shunting. There was no difference in mean age, gender distribution, or severity of hepatic disease in those with and without evidence of such shunting. Although there was no difference in mean partial arterial oxygen pressure (PaO2) values in the 2 groups (82 +/- 11 vs 76 +/- 11 mm Hg), the mean PaO2 value of those with at least 2+ left ventricular opacification (2 to 4+) was significantly lower (66 +/- 3 mm Hg, n = 8; p less than 0.01). Unexpectedly, patients with evidence of intrapulmonary shunting had a lower mortality rate before transplantation (3 of 25, 12%) than those without evidence of shunting (10 of 28, 36%) resulting in a significant difference in actuarial survival (p less than 0.05) by the end of the follow-up period. It is concluded that intrapulmonary right-to-left shunting occurs frequently in patients with end-stage liver disease and may be a marker of a positive biologic process that, in some way, leads to improved short-term survival.

Severe hypoxemia-associated intrapulmonary shunt in a patient with chronic liver disease: improvement after medical treatment

A 20-yr-old woman with chronic liver disease and angioimmunoblastic lymphadenopathy presented with marked hypoxemia caused by intrapulmonary shunt. Her respiratory tract showed her to be free of angioimmunoblastic lymphadenopathy manifestations. After 12 months of treatment with cyclophosphamide and corticosteroid, the immunologic disease disappeared. Unexpectedly, hypoxia-associated intrapulmonary shunt was no longer present either. To the best of our knowledge, this is the first case of dramatic improvement, with medical therapy, of severe hypoxemia related to noncirrhotic liver disease. However, the mechanism by which this treatment caused the regression of intrapulmonary shunt is unknown.

Liver transplantation: an unheralded probable risk for tuberculosis

We present a patient who underwent orthotopic liver transplantation and died of previously undiagnosed pulmonary tuberculosis (TB). TB is known to complicate liver transplantation in rare circumstances. Liver transplantation is an unheralded risk factor for development of TB because of possible activation of latent infection or primary TB in immunosuppressed hosts. A tuberculin skin test should always be performed preoperatively. Preventive treatment with isoniazid is indicated when immunosuppressive therapy is started in patients with high TB risk. Radiographic signs of previous granulomatous disease may be important when tuberculin skin test is negative, unknown or anergy is present. TB is preventable--with a high degree of suspicion where TB is endemic and proactive programs, most TB cases in transplant recipients can be avoided.

Hypoxia and cyanosis in alpha-1-antitrypsin deficiency. Cirrhosis as an unusual etiologic factor

A patient with type PiZZ alpha-1-antitrypsin deficiency was found to have severe hypoxia despite normal pulmonary function testing and a normal chest radiograph. A nuclear medicine ventilation-perfusion study revealed a right-to-left shunt. Computed tomography showed minimal bleb formation, no diffuse changes, and hepatic changes of cirrhosis with portal hypertension. No nodular pulmonary masses or enlarged peripheral pulmonary vessels were found. The diagnosis of diffuse intrapulmonic arteriovenous shunts ("pulmonary spiders of cirrhosis") was suggested and then confirmed with a dynamic radionuclide flow study.