Background and aim of the work: Sarcoidosis is a granulomatous disease with frequent pul monary involvement. Patients generally exhibit a 25-30% reduction in maximal aerobic capacit (VO2max). As most investigations have included patients with both normal and abnormal resting pulmonary function tests (PFT), the mechanisms responsible for this limitation remain unclear. We initiated a prospective study to characterize the cardio-respiratory response to exercise in sarcoid patients with normal resting PFT.
Methods: 19 untreated male patients with biopsy-proven sarcoidosis and 19 age- an sex-matched sedentary healthy controls (38 +/- 8.7 vs 37 +/- 8.7 yrs ; Body Mass Index: 24 +/- 3.05 vs 23 +/- 3.05) were included in the study. All patients had normal resting PFT including diffusing capacity for CO (DLCO) > 80% predicted and normal cardiac status at rest as assessed by EKG and echocardiography. A maximal cycling test was performed in all subjects.
Results: True maximal effort was obtaine in all subjects (plasma lactate 9.1 +/- 2.6 vs 11.0 +/- 2.2 mmol l(-1), pH 7.35 +/- 0.04 vs 7.34 +/- 0.04) (patients vs controls). Patients exhibited a 30% lower maximal workload and/or VO2max (2,128 +/- 413 vs 2,909 +/- 387 ml x min(-1)) than controls. Maximal ventilation (79 +/- 21.7 vs 110 +/- 21.7 l x min(-1)) and tital volume (VT) (2,313 +/- 517 ml vs 2,856 +/- 339) were significantly lower in patients than in controls while dead space t tital volume ratio (VD/V(T)) (0.18 +/- 0.09 vs 0.11 +/- 0.04) was higher in patients than in controls. PaO2, PAiO2, and PAi-aO2 at VO2max were not significantly different between patient and controls. Peak exercise EKG was normal in all but one patient. Interestingly, heart rate was significantly lower in patients for all relative exercise intensities > or = 60% VO2max including maximum (159 +/- 21.7 vs 182 +/- 13)
Conclusion: The present observations indicate a significant maximal exercise limitation in sarcoid patients without significant pulmonary impairment which could be related at least in part to an impaired heart rate response to exercise.