Amiodarone lung toxicity: role of pulmonary function tests

Forty-three patients treated with amiodarone hydrochloride with an average daily dose of 204.7 +/- 79.4 mg/day for a mean period of 37.1 +/- 25.3 months, were studied by clinical examination, chest roentgenograms, pulmonary function tests and blood gas analyses. The habits of cigarette smoking were also recorded and expressed as cigarette pack/years. Pulmonary function tests did not show any differences from control subjects and no correlation was found between exposure to drug and lung function. However, one patient developed abnormalities in the chest X-ray (interstitial type) and a reduction of carbon monoxide diffusion capacity as a possible manifestation of amiodarone lung toxicity. Nine patients (22%) had a 20% decrease from normal in carbon monoxide diffusion capacity and three (7%) had a 15% decrease in total lung capacity. More treated patients had interstitial abnormalities in the chest X-ray (14%) than controls (5.5%). Although pulmonary function test abnormalities could be detected in patients taking amiodarone, they were not usually severe enough to interfere with gas exchange. Our results confirm the rarity of amiodarone lung toxicity when a low dosage is used, and suggest the advisability of periodical monitoring, including clinical examination, chest X-ray and pulmonary function tests in order to detect the earliest signs of amiodarone lung toxicity.