The Science Journal of the American Association for Respiratory Care
BACKGROUND: Closed-chest compression during cardiopulmonary resuscitation (CPR) is an important lifesaving procedure.1 Breathing assistance devices, such as manual bag-valve and automatic resuscitators, are pressure sensitive, and their function is affected by chest compression. As breathing assistance devices evolve, the need exists to test these devices, techniques, and equipment to ensure their safety and efficacy. Such a system is described below.
EQUIPMENT: The lung environment was simulated by a commercially available lung simulator (SMS, England MS0015001). An external compression simulator was attached to its structure as well as a pressure tap for data acquisition. The simulator was equipped with controls to regulate cycle rate, speed, force, and distance. The lung compression device was comprised of an air cylinder with bi-directional flow adjustments to control compression speed, a pressure adjustable air supply to control maximum force, and control circuits and a solenoid valve for actuation. The cylinder mount directed the cylinder rod against the mechanical test lung and a stop was mounted to the frame to simulate the maximum depth of an external compression. A fine adjustment scale on the speed and pressure control was essential to ensure repeatability.
METHODS: A breathing device, such as a manual bag-valve or automatic resuscitator, was used to simulate inhalation and exhalation functions. The chest compression simulator was cycled to simulate CPR. This was helpful in evaluating synchronous and non-synchronous compressions with breathing cycles at various compression rates.
RESULTS: The compression rate was set at 80 times per minute with a ratio of 5 compressions per breath. The proximal airway pressure waveform was recorded utilizing a computer data acquisition system. The pressure waveform represented external chest compressions during resuscitation.
CONCLUSION: Because this lung compression system is so versatile, it can be used to evaluate many different types of respiratory devices. In this case, closed chest compressions were simulated under controlled conditions. This system can be effectively used to test the safety and efficacy of other breathing assistance devices.
Supported by VORTRAN Medical Technology 1, Inc.
1. National Conference on Cardiopulmonary Resuscitation and Emergency Cardiac Care. Standards and guidelines for cardiopulmonary resuscitation (CPR) and Emergency Cardiac Care (ECC). JAMA 1986;255(21):2905-2984.
(See Original for Figure)