PULMONARY-ARTERY PRESSURE VARIATION IN PATIENTS WITH CONNECTIVE-TISSUE DISEASE - 24-HOUR AMBULATORY PULMONARY-ARTERY PRESSURE MONITORING

Background-The specific contribution of secondary pulmonary hypertensi on to the morbidity and mortality of patients with underlying lung dis ease can be difficult to assess from single measurements of pulmonary artery pressure. We have studied patients with secondary pulmonary hyp ertension using an ambulatory system for measuring continuous pulmonar y artery pressure (PAP). We chose to study patients with connective ti ssue disease because they represent a group at high risk of pulmonary vascular disease, but with Little disturbance of lung function. Method s-Six patients (five with progressive systemic sclerosis and one with systemic lupus erythematosis) were studied. They underwent preliminary cardiopulmonary investigations followed by Doppler echocardiography, right heart catheterisation, and ambulatory pulmonary artery pressure monitoring to measure changes in pressure over a 24 hour period includ ing during a formal exercise test.Results-All patients had pulmonary h ypertension as measured by Doppler echocardiography with estimated pul monary artery systolic pressures of 40-100 mm Hg. Pulmonary function t esting revealed virtually normal spirometric values (mean FEV1 86.9% p redicted) but marked reduction in CO gas transfer factor (Kco 57.8% pr edicted). Exercise responses were impaired with mean Vo(2)max 50.6% pr edicted. Ambulatory PAP monitoring indicated significant changes in pr essures with variation in posture and activity throughout 24 hours. Re sting PAP did not predict the change in PAP seen on exercise. Conclusi on-Conventional methods of assessment of the pulmonary circulation bas ed on single measurements in the supine position may underestimate the stresses faced by the right side of the circulation. This ambulatory system allows monitoring of pulmonary haemodynamics continuously over 24 hours during normal activities of daily living. These measurements may increase our understanding of the contribution made by secondary p ulmonary hypertension to the morbidity and mortality of the underlying lung disease.