An evaluation of positive expiratory pressure using mask and mouthpiece

The aim of the trial was to investigate positive expiratory pressure (PEP) using mask or mouthpiece regarding pressure during constant flow and resistance, dead-space volume and how postoperative patients perform and estimate perceived exertion during the breathing exercises. Twenty volunteers were included in the first part where a PEP valve, connected to a mask or mouthpiece, was used and pressure in the system was measured during constant gas flows and resistances. Dead space in each system was measured with water. In the clinical part, 40 patients undergoing abdominal surgery were included where the degree of leakage from the device was observed and perceived exertion was estimated during the sessions with PEP by mask or mouthpiece. The results revealed a significantly higher expiratory pressure when using the mouthpiece compared with mask, irrespective of flow and resistance (p<0.05). Dead space was greater when using the mask (170±7 vs. 26 ml). In the clinical part, there were no significant differences in the outcome variables between the groups concerning degree of leakage and estimated perceived exertion. The mouthpiece produces higher positive pressure and smaller dead space compared with the mask. Half of patients failed to use the systems correctly.