The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

COMPARISON OF POSITIVE EXPIRATORY PRESSURE (PEP) VALVES: A LABORATORY STUDY.

James B. Fink, MS, RRT., Hines VA Hospital and Loyola Univ. Chicago, Stritch School of Medicine, Hines IL.

Several devices have been recently approved by the FDA for use in airway clearance with scant data demonstrating physical effects of the devices on airway and lung mechanics. AARC clinical guidelines for Positive Airway Pressure identifies fixed orifice (FO) resistors as the mechanism used to apply Positive Expiratory Pressure (PEP). The aim of this study was to compare and characterize three fixed orifice resistors marketed as PEP devices The Resistex (Mercury Medical), TheraPEP (DHD) and Westmed PEP (Westmed) resistors were attached to a CP-100 Pulmonary Monitor (Bicore) to determine effects on airway pressure patterns, peak expiratory flows (PEFR; L/min), peak expiratory pressure (Pexp; cmH_{2}O), work of breathing (W_{pt};Joule/L), pressure time product (PTP) of passive exhalation (VT 500 ml, PIF 40 L/min) simulated with a test lung driven by a mechanical ventilator. A comparison of the devices' largest (L) and smallest (S) orifices are shown below:

PEFR Pexp WOB(pt) PTP

Resistex (L) 14.4 6 0.690 52

Resistex (S) 4.8 7 0.680 53

TheraPEP(L) 17.4 6 0.560 44

TheraPEP (S) 6.1 7 0.630 48

WestMed (L) 36.0 3 0.480 36

WestMed (S) 16.8 7 0.520 41

Range of PEFR, WOB and PTP differed between devices (p < 0.05; ANOVA). Pexp was lower than recommended therapeutic levels of 10 - 20 cmH_{2}O for all devices studied. Passive exhalation, as simulated, may not be adequate to generate therapeutic pressures with these devices.

In conclusion, there are significant differences in the ranges of flow restriction with the three fixed orifice PEP devices studied.

Reference: OF-96-188

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