INHALED NITRIC-OXIDE TEST FOR PATIENTS WI TH CHRONIC LUNG-DISEASE - INTEREST AND RELIABILITY

Patients suffering from chronic lung disease (CLDP) often develop seco ndary pulmonary hypertension (HP), which contributes to light ventricu lar dysfunction and worsens their prognosis. In order to evaluate the severity of this HP, pharmacodynamics tests are periodically proposed to these patients. Therefore, the administration of vasodilators is li mitated by systemic and pulmonary side-effects. Inhaling nitric oxide gas (NO) has been reported to induce a selective pulmonary vasodilatat ion. The purpose of this study was to evaluate the safety and efficacy of an inhaled NO test perfected in our service. Sixteen CLDP were inv estigated in the absence of acute pulmonary failure. All had severe pr e-capillary HP, confirmated after placement of a thermodilution pulmon ary-artery catheter (mean pulmonary artery pressure >20 mmHg, pulmonar y capillary wedge pressure >12 mmHg). Each subject breathed spontaneou sly NO in a concentration of 10 ppm for. 15 minutes. They were connect ed through a facial mask and a one-way valve put on the inspiratory co nnection of a ventilator (Drager-Evita), to a tank of nitrogen with a NO concentration of 900 ppm. Hemodynamic variables and gas exchange we re measured before, during and after gas inhalation. The inspirated fr actions of NO and NO2 were determinated using a Polytron analyser (Dra ger). The methemoglobin levels were measured with spectrophotometry (O SM3). Inhaled NO acts as a selective pulmonary arterial vasodilator; w ithout systemic effect. The action on the shunt is variable. Methemogl obin levels are remained <0.01%. All the patients were satisfied with the way of NO administration. In view of the lack of systemic effects, its seems that the NO inhaled test proposed in this study may De used accurately to evaluate the HP of chronic lung disease patients.