ESTIMATION OF VENTILATORY RESERVE BY STAIR CLIMBING - A STUDY IN PATIENTS WITH CHRONIC AIR-FLOW OBSTRUCTION

Clinicians and surgeons have used the subjective response to the climb of ''one or two flights of stairs' to assess the ''reserve'' of patie nts with chronic airflow obstruction (CAO). Very little objective data exist regarding the metabolic and ventilatory cost for any level of s tair climbing in these patients. Therefore, this study was designed to evaluate the use of symptom-limited stair climbing as a simple method to estimate the peak oxygen uptake (Vo2) and minute ventilation (VE) in patients with CAO. We studied 31 men with varying degrees of CAO, w ho climbed stairs until they stopped at their symptom-limited maximum. During this climb, timed expired ps was intermittently collected and analyzed, and oxygen saturation and heart and respiratory rates were r ecorded. The patients achieved 81 +/- 14 percent of their predicted ma ximal heart rate and 90 +/- 27 percent of their predicted maximal VE. The number of steps or flights climbed correlated linearly with peak V o2 (r=0.72, p<0.01) and with VE (r=0.7, p<0.01). Stair climbing peak V E, VO2, heart and respiratory rate correlated well with those achieved during leg cycle ergometry. The mean +/- SD number of flights climbed was 4.2 +/- 1.7 with most patients (87%) reaching at least 3 flights (54 steps). The group of eight patients with very severe CAO (FEV1 <0. 9 L) climbed 3.4 +/- 0.9 flights (61 +/- 16 steps). We conclude that a symptom-limited maximal stair climb helps estimate peak VO2 and VE in patients with CAO. The frequently advocated test to climb one to two flights to evaluate cardiopulmonary reserve is not adequate for most p atients with CAO. Symptom-limited maximal stair climbing is a simple, inexpensive and readily available test that may be used to evaluate th e cardiopulmonary reserve of stable patients with CAO.