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Hepatopulmonary Syndrome Unmasked by Interstitial Pneumonitis

Oregon Health Sciences University, Portland, OR

INTRODUCTION: We present a case of hepatopulmonary syndrome which was unmasked by interstitial pneumonitis resulting from a drug exposure.

CASE REPORT: MB is a 43 year old male with Childs Class A cirrhosis secondary to hepatitis C who presented with increasing dyspnea on exertion and dry cough over a one month period. He had previously been well but was now winded with minimal exertion and reported his fingertips turning blue with one flight of stairs. Six weeks prior he had begun therapy with ribaviron and alpha interferon. Past medical history was otherwise noncontributory.

Vitals: BP 130/65, R 18, HR 78, O2 saturations 90% on room air (RA) at rest, 84% with ambulation. Exam notable for bibasilar inspiratory rales and clubbing. Chest radiograph revealed interstitial opacities. High resolution CT chest confirmed subpleural interstitial fibrosis with ground glass attenuation predominantly in the bases. He was also noted to have significant orthodeoxia, with RA O2 saturations of 78% while standing and 93% in the supine position. ABG’s revealed a PaO2 of 55 on RA and 266 on 100% oxygen (mmHg). Physiologic shunt estimated at 15-20%. Delayed positive contrast echocardiogram confirmed intrapulmonary shunt.Pulmonary angiogram showed no arteriovenous malformations. Extrapulmonary (brain) uptake of radioisotope was demonstrated to be 8.5% on 99mTcMAA lung scan.

The patient was diagnosed with hepatopulmonary syndrome (HPS), as well as an interstitial pneumonitis secondary to his Hep C medications. These were discontinued, a trial of steroids was initiated and the patient was listed for liver transplantation.

He reported significant symptomatic improvement within weeks. Follow up CT chest showed improvement with resolution of ground glass attenuation and some mild residual fibrosis. Repeat ABG two months after presentation now showed a PaO2 of 81 on RA and 428 on 100% oxygen (mmHg).

DISCUSSION: We present a case of HPS that was unmasked by a concomitant interstitial pneumonitis. Alpha interferon and ribaviron have been implicated as a cause of reversible interstitial pneumonitis.1 HPS is defined as the clinical triad of chronic liver disease (cirrhotic or non cirrhotic), arterial hypoxemia (PaO2 < 70 mmHg or AaO2 gradient > 20 mmHg)) and intrapulmonary vascular dilations.2 Interestingly, the degree of hypoxemia associated with HPS is not related to the severity of liver disease.3 Orthotopic liver transplantation may result in complete resolution of HPS, but carries a higher surgical mortality.4 The co-existence of intrinsic lung abnormalities in addition to HPS has been reported in 20 % to 31% of patients.3

Given the rapid progression of symptoms, we postulate that he had clinically silent HPS and the additional insult to his gas exchange by the interstitial process caused hypoxemic vasoconstriction. This effectively shunted more blood through his pulmonary vascular dilatations. In addition, by treating the pneumonitis we were able to demonstrate improvement in the shunt, although it remains present.

CONCLUSION: Severity of HPS may be increased by concomitant defects in gas exchange, as seen with interstitial pneumonitis. By treating the pulmonary process, the degree of shunt from HPS may be lessened, although not eliminated. Liver transplantation remains the best treatment for HPS.

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REFERENCES

1. Karim A, et al. Interstitial pneumonitis in a patient treated with alpha-interferon and ribaviron for hepatitis C infection. Am J Med Sciences. 2001;322:233–235
2. Krowka MJ, Hepatopulmonary syndrom: recent literature (1997-1999) and implications for liver transplantation. Liver Transpl. 2000;6:S31–S35
3. Krowka MG, et al. Hepatopulmonary Syndrome: A prospective study of Relationships between severity of liver disease, PaO2 response to 100% oxygen and brain uptake after 99mTcMAA lung scanning. Chest. 2000;118:615–624
4. Arguedas MR, et al. Prospective evaluation of Outcomes and predictors of mortality in patients with hepatopulmonary syndrome undergoing liver transplantation. Hepatology. 2003;37:192–197