The Science Journal of the American Association for Respiratory Care

1995 OPEN FORUM Abstracts

OPTIMAL WORK OF BREATHING WITH NEGATIVE PRESSURE VENTILATION

Timothy J. Cox, RRT, John J. McCloskey, M.D., A. I. duPont Institute, Thomas Jefferson Medical University, Wilmington, DE 19899

Since its early use, negative pressure ventilation (NPV) has been used in a control mode for patient's with neuromuscular disease. Recently, it is being used in other clinical situations such as post op cardiac patients. The conventional negative pressure ventilator can only be adjusted in terms of rate and negative pressure. However, microprocessor technology has led to the development of negative pressure ventilators, such as the Life Care NEV 100^{TM}, which allows for an assist mode of ventilation and the incorporation of extrathoracic positive pressure during ventilation cycles. Titration of optimal settings with a conventional negative pressure ventilator is to patient comfort and ABGs. We present a case report in which NPV for a 14 month old child with pulmonary hypoplasia was optimized by evaluating pulmonary mechanics. To date ,there is no literature on using pulmonary mechanics to titrate NPV.



Methods: The child was placed in a Porta - Lung^{TM} with a Life Care NEV 100^{TM} NPV attached. Pulmonary mechanics were evaluated using the Bicore CP-100 Neonatal Pulmonary Monitor^{TM} at various levels of support. Respiratory rate (RR), peak inspiratory and expiratory flow rates (PIFR, PEFR), dynamic compliance (CLD), work of breathing (WOB), mean airway resistance (Rmean), and expiratory resistance (Rex) were obtained for 10 breath cycles and graphed as follows.

SEE ORIGINAL GRAPH



Results: Pressures of -10 and base +5 proved to be the optimal pressures as reflected by a decrease in WOB, RR, Rmean, Rex and an increase in CLD and PIFR.



Conclusions: NPV was optimized in this patient by measuring pulmonary mechanics. Validation of this method for titrating NPV will require studying more patients.

OF-95-205

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