[abstract] EVALUATING THE SAFETY, FUNCTION AND USE OF MEDICAL VENTILATORS TO PROVIDE RESPIRATORY SUPPORT OF CRITICALLY ILL PATIENTS IN THE HYPERBARIC CHAMBE

Abstract

BACKGROUND: The U.S. Navy has continuing needs to identify medical equipment that can be safely used during hyperbaric chamber treatments. Currently, Navy chambers use only the Penlon Oxford ventilator - which has not been produced since the 1980s, and for which repair parts are difficult to obtain. To replace the Penlon, NEDU has identified several ventilators, most of which are pneumatically powered, microprocessor controlled, and pressure or time cycled. Capable of ventilating patients from infants through adults, some contain internal, sealed, gel-cell, lead acid batteries that will be tested separately. METHODS: Tests conducted in 2001 determined whether units were safe for chamber operation: a minimum flow rate of 10 L/min at a depth of 6 ATA was established as a performance standard for testing and evaluating functional performance of respirators. Chamber pressure affects functions such as tidal volume, flow rate, and peak airway pressures - functions recorded with a Michigan test lung. RESULTS: Of 11 ventilators were selected for study, four passed safety requirements and could provide sufficient flow at depth: Impact Eagle, Newport, Omni-Vent, and Penlon Multivent. Troubling large disparities in peak proximal airway pressures resulted from orifice design in the test lung. For all ventilators except one, flow rates had to be increased to achieve the required 10 L/min flows at 6 ATA, and the four successfully tested ventilators required gas supply pressures maintained at 50 psi over bottom. CONCLUSION: The ventilators successfully completing evaluation can operate safely in Navy chambers. Following their successful completion of the test protocol, these devices will be added to the NEDU list of acceptable medical equipment. Ventilator, Hyperbaric Chamber Full paper here: http://archive.rubicon-foundation.org/3488