Pulmonary blood transit time and impaired arterial oxygenation in patients with chronic liver disease

Abstract

Background

Contrast-enhanced echocardiography (CEE) using agitated saline can detect intrapulmonary vasodilatation (IPVD) in patients with hepatopulmonary syndrome (HPS). We estimated the pulmonary transit time of erythrocytes (PTT) by CEE, using microbubbles, and studied its relationship to arterial oxygenation in chronic liver disease.

Methods

Sixteen patients with chronic liver disease and seven healthy subjects were studied. PTT was defined as the time between opacification of the right atrium and left atrium on CEE, using human serum albumin-air microbubble complexes with a mean diameter of 4 µm (Albunex). IPVD was detected by CEE with agitated saline. Arterial blood gases were analyzed with patients in the supine position, and while they were seated. Cardiac output (CO) was determined by Doppler echocardiography.

Results

The mean PTT value for all of the patients was 4.0 ± 1.4 s. One of the 3 patients who showed IPVD was normoxemic. Mild orthodeoxia was observed in the patients with abnormal alveolar-arterial oxygen difference (A-aDO₂) values (>15 mmHg), but not in those with normal A-aDO₂ values, or in the healthy subjects. PTT was correlated with PaO₂ (r = 0.52; P < 0.05; n = 16) and A-aDO₂ (r = −0.54; P < 0.05; n = 16) in the seated position. CO was significantly correlated with PTT (r = −0.62; P < 0.05; n = 15), but not with PaO₂ and A-aDO₂, in both positions.

Conclusions

PTT may be a useful parameter for evaluating arterial oxygenation in patients with chronic liver disease with early HPS.