PULMONARY ARTERIAL WEDGE PRESSURE MEASUREMENT CAN MODIFY PULMONARY HEMODYNAMICS IN PATIENTS WITH CHRONIC LUNG-DISEASE

In 20 patients with chronic lung disease in stable condition, haemodyn amic values were compared during wedging of a Swan-Ganz catheter, eith er in a distal branch of the pulmonary artery, or by balloon inflation (with 1 ml) in a proximal branch, mostly excluding right lower lobe p erfusion. Average pulmonary arterial wedge pressure, systemic arterial pressure, transcutaneous and mixed venous oxygen saturation, cardiac output and pulmonary blood volume (PBV) were not statistically differe nt during distal and proximal wedging, but systolic pulmonary arterial pressure and pulmonary vascular resistance were slightly higher durin g balloon inflation (P<0.05). In four patients, PBV decreased by 20% o r more; cardiac output was reduced and mean systemic arterial pressure diminished by 10 mmHg or more in three patients. Of the two patients with the lowest PBV, one did not tolerate the balloon inflation becaus e of dyspnoea, and the other showed dramatically haemodynamic changes. These were more likely to occur when the occlusion lead to the exclus ion of a still well perfused area. Our results support optimal matchin g between ventilation and perfusion in patients with chronic lung dise ase, although both are inhomogeneous. When pulmonary vascular restrict ion can be suspected, pressure obtained during catheter wedging by bal loon inflation should be interpreted with caution. Monitoring arterial oxygen saturation and systemic arterial pressure before and during th e manoeuver could help to diagnose haemodynamic effects of the balloon inflation in a proximal pulmonary artery.