Nitric oxide production by the alveolar compartment of the lungs in cirrhotic patients

¹ Service de Pneumologie et Réanimation Respiratoire, Centre National de Référence de l'Hypertension Artérielle Pulmonaire, Hôpital Antoine Béclère, Clamart, France
² Service d'Exploration Fonctionnelle Respiratoire, CHU Larrey, Toulouse, France
³ Service de Pneumologie et Réanimation Respiratoire, Centre National de Référence de l'Hypertension Artérielle Pulmonaire, Hôpital Antoine Béclère, Clamart, France; and Centre Chirurgical Marie-Lannelongue, 92350 Le Plessis-Robinson, France
⁴ Dépt de Néphrologie, Dialyse et Transplantation d'Organes, CHU Rangueil, Toulouse, France

^* To whom correspondence should be addressed. E-mail: degano.b{at}gmail.com.

	Abstract

In cirrhotic patients, alveolar nitric oxide (NO) concentration is increased. This may be secondary to increased production of NO by the alveolar compartment of the lungs (V'A,NO) and/or to decreased lung transfer of NO. In advanced liver cirrhosis, NO produced by the alveoli may play a role in abnormalities of pulmonary haemodynamics and gas exchanges. In cirrhotic patients, we aimed to measure V'A,NO, and to compare V'A,NO with pulmonary haemodynamics and gas exchange parameters.

Measurements were performed in 22 healthy controls and in 29 cirrhotic patients, of whom 8 had hepatopulmonary syndrome. Exhaled NO concentrations were measured at multiple expiratory flow rates to derive alveolar NO concentration. V'A,NO was the product of alveolar NO concentration by single breath lung transfer for NO.

V'A,NO was increased in patients (median [range] 260 [177–341] nL·min^-1) compared with controls (79 [60–90], p<0.0001). Alveolar-arterial oxygen tension difference failed to correlate with V'A,NO. However, cardiac index correlated positively and systemic vascular resistance correlated negatively with V'A,NO (r=0.56, p=0.001, and r=0.52, p=0.004, respectively).

In cirrhotic patients, NO was produced in excess by the alveolar compartment of the lungs. Alveolar NO production was associated with hyperdynamic circulatory syndrome but not with arterial oxygenation impairment.