The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

EVALUATION OF AN INSPIRATORY IMPEDANCE VALVE

Thomas A Barnes EdD RRT, Sarah K Melville, Keith G Lurie* MD, Department of Cardiopulmonary Sciences, Northeastern University, Boston, Massachusetts, *Arrhythmia Center, Department of Medicine, University of Minnesota, Minneapolis.

We evaluated the performance and safety of a prototypic inspiratory impedance valve, Resuscitator Valve^{TM} (CPRx Inc). The valve when attached to the patient connection of a manual resuscitator is designed to increase the duration and magnitude of negative intrathoracic pressure during CPR. In animal models of ventricular fibrillation the Resuscitator Valve has been reported to enhance venous return and vital organ perfusion during CPR. This device was awarded United States Patent 5,692,248 on Dec. 2, 1997. The Resuscitator Valve was tested while connected to a Spur manual resuscitator (Ambu Inc). Method: We used standards and methods approved by American Society for Testing and Materials (F 920-93, ASTM Committee on Standards, Philadelphia, 1993) and International Organization for Standardization (ISO 8382:1988E, New York, 1988). A Bio-Tek VT-1 Ventilator Tester was used as a lung model with C=0.02 L/cm H_{2}O [0.20L/kPa] and R=20 cm H_{2}O.s.L^{-1} (2 kPa.s.L^{-1}). Results: The Resuscitator Valve used with the Spur met ASTM and ISO standards for V_{T} (600 mL), f (20/min), and I:E ( < 1:2). The ASTM and ISO standards specify an FDO_{2} of >= 0.85 with O_{2} reservoir and O_{2} flow of 15 L/min and V_{E} of 7.2 L/min (V_{T} 600 mL, f 12/min). The Resuscitator Valve used with the Spur had a FDO_{2}, mean (SD), of 0.97 (0.01). When tested with simulated vomitus the Resuscitator Valve attached to the Spur manual resuscitator was able to be restored to proper function within 20 seconds. The mechanical deadspace of the Resuscitator Valve was determined to be less than 5% of the tidal volume recommended by the American Heart Association for resuscitation of adults. Inspiratory and expiratory resistance were measured at a flow of 50 L/min. The Resuscitator Valve when attached to the Spur manual resuscitator passed the test for expiratory resistance (pressure < 5 cm H_{2}O). The Resuscitator Valve when attached to the Spur required an inspiratory pressure, mean (SD), of -22.4 (.01) cm H_{2}O. Conclusions: We conclude that the Resuscitator Valve when attached to the Spur manual resuscitator generates the intended negative inspiratory impedance. The Resuscitator Valve used with the Spur does not significantly effect the expiratory resistance, FDO_{2}, valve clearance of vomitus, tidal volume, or cycle rate. Because the valve adds deadspace and requires > -5 cm H_{2}O to open, we recommend that it be removed from a manual resuscitator when return of spontaneous circulation and breathing occurs. We conclude based on testing that the Resuscitator Valve is in substantial compliance with ASTM and ISO standards.

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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