FIXED MAXIMAL STROKE INDEX IN PATIENTS AFTER PNEUMONECTOMY

Patients who have undergone pneumonectomy (PNX) show limited exercise capacity, partly attributable to an impaired stroke index (SI). To det ermine whether this limitation is due to deconditioning, we assessed e xercise performance and cardiopulmonary function in seven patients aft er PNX (age: 59 +/- 2 yr, mean +/- SEM) and eight normal, healthy nons mokers (52 +/- 3 yr) before and after an ergometer exercise training p rogram for 30 min per day, 5 d per week, for 8 wk at 65% of measured m aximal O-2 uptake. Lung volume, diffusing capacity of carbon dioxide ( DLCO) and cardiac index (CI) were determined during steady-state exerc ise by a rebreathing method. Exercise endurance was measured at 80% of maximal power. As compared with normal subjects, patients who had had PNX showed diminished maximal oxygen uptake ((V) over dot O-2max), as well as diminished lung volumes, ventilatory capacities, and maximal cardiac and stroke indexes. After training, (V) over dot O-2max, endur ance, and peripheral O-2 extraction improved in both groups. However, maximal cardiac and stroke indexes increased only in normal subjects a nd not in patients. We conclude that an irreversibly fixed maximal Sr is a major source of exercise limitation after PNX, probably because o f pulmonary arterial hypertension and/or mechanical distortion of the cardiac fossa. Ventilatory impairment after PNX did not prevent a trai ning-induced increase in (V) over dot O-2max. Exercise training confer s significant functional benefit on postpneumonectomy patients by enha ncing peripheral O-2 extraction.