**1. Introduction**

The hyperbaric chamber is an active medical device, which is potentially hazardous taking into accounts its application and exposure of people inside to increased ambient pressure and increased partial pressure of oxygen. Typically, in most clinical indications, the internal pressure of 2.5 absolute atmosphere (ATA) (equivalent to 15 m of sea water [msw]) is used, with the range from 1.5 to 6.0 ATA (equivalent to 5–50 msw), for a period of 60 min, with the range from 30 to 120 min, as depending on the specific hyperbaric center [1]. Regardless of using the monoplace chamber, where patient is left alone within the pressure vessel, or in multiplace chamber, where patient is staying in the larger internal space together with medical attendant, as with other patients, if so organized, in all cases, any medical device, either external to the patients or implanted, including Implantable Cardiac Defibrillators (ICD) and Pacemakers (PM), is exposed to increased ambient pressure.

Use of other medical devices for therapeutic purpose in the hyperbaric chamber is also related with additional hazards due to increased pressure, oxygen-enriched atmosphere, electricity, and confined space. Therefore, every medical device introduced into the hyperbaric chamber should be designed in that way that its use in the hyperbaric chamber does not create significant risk of malfunction, damage, or ignition of fire in the hyperbaric environment; this should be certified by the manufacturer for specific conditions (working pressure, maximum allowable content of oxygen, temperature, and humidity). Unfortunately, until now only few medical devices are specifically designed for usage in hyperbaric chambers.

Therefore, medical providers often need to conduct themselves appropriate assessment of the medical equipment needed for continuation of intensive or general care during hyperbaric treatment.
