Positive end expiratory pressure (PEEP) slightly modifies ventilatory response during incremental exercise

To clarify the ventilatory effects of a 5-cm H2O positive end expiratory pressure (PEEP) in healthy men during incremental exercise in normoxic conditions, 22 subjects were subjected to a constant workload (0 W, 50 W, 100 W, 150 W and 200 W) on a cycle ergometer for periods of 8 min each, both with and without 5-cm H2O PEEP. Results show that PEEP increases inspiratory (TI) and expiratory (TE) duration and tidal volume (VT) and decreases breathing frequency (fB) at rest (p < 0.05). During exercise, TI is higher at 50 W and 100 W (p < 0.05), but not at 150 and 200 W. TE only increases at 50 W (p < 0.05). An increased VT (p < 0.05 at 50, 100 and 150 W) and a decreased fB (p < 0.05 throughout the experiment) were observed. However, mean inspiratory flow (VT/T1) and duty cycle (TI/TT) were unaffected by PEEP. In conclusion, this study shows that a 5-cm H2O PEEP slightly modifies the ventilatory parameters in healthy subjects during incremental exercise in normoxic conditions.