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Abstract
Hyperbaric Oxygen Therapy [HBOT] is a widely accepted treatment for patients suffering from conditions associated with low oxygen content or delivery. HBOT utilizes a pressurized environment [typically 2.4 to 2.8 atmospheres absolute] and high fraction of inspired oxygen to drive oxygen deep within the body’s tissues to facilitate healing. Although a variety of patients may benefit from this therapy, many medical devices have not been tested in the hyperbaric environment, including ventricular assist devices [VADs]. Such testing needs to consider the mechanical operation of VADs and the environmental changes that occur with HBOT. There are few published documents describing the ability of VADs to function during descent to a therapeutic depth and the return to surface pressure that occur with HBOT.
The main goal of this study was to determine if two common VADs [HeartMate II and HeartWare] and their components would properly function during HBOT. The specific hypothesis tested was that the LVADs and their components would maintain function throughout the duration of the testing without suffering any damage from a pressurized mono-place chamber. One parameter used to assess adequacy of VAD function was the ability of the VAD to maintain flow within 1 liters per minute [LPM] of the initial flow at pressures ranging up to 2.8 ATA in the mono-place hyperbaric chamber. Thoratec’s HeartMate II Left Ventricular Assist System [HM II LVAS] was powered in the mono-place chamber using its mobile power unit [MPU]. The MPU utilizes AC power, which met the requirements stated in the 2018 version of the National Fire Protection Agency 99 guidelines for safe use of the medical device within a hyperbaric chamber. Medtronic’s HeartWare Ventricular Assist System [HW VAS] was powered using its AC adapter. Again, the setup met the requirements stated in the 2018 version of the National Fire Protection Agency 99 guidelines for safe use of the medical device within a hyperbaric chamber.
The HM II LVAS maintained flow within ±0.25 LPM of the VAD’s initial flow during testing in the mono-place chamber. The HM II LVAS remained completely functional for the entirety of testing and no components suffered any damage from the pressurized environment. The HW VAS maintained flow within ±0.50 LPM of the VAD’s initial flow during testing in the mono-place chamber. The HW VAS remained completely functional for the entirety of testing and no components suffered any damage from the pressurized environment. The results of this study indicate that the mechanical operation of the VADs will function appropriately at high pressures during HBOT. However, prior to utilizing HBOT for a VAD patient, extra safety precautions, such as N2 purging of electrical components and the use of non-explosive/waterproof fittings for AC power cords, should be implemented and tested.