ICUs are often equipped with telemetry equipment, which can explain the problems in Apple Watch Series 3 and without mobile connectivity support. Complaints on Apple's smart watch is also delivered by a hospital nurse who rewards Apple Watch Series 3 to her husband.
The nurse complained about the device starting to reboot every 60-90 minutes, while in the vicinity of the ICU. In addition, the nurse also claimed to have replaced his Apple Watch, but the same problem re-occur.
The Apple Support site is also enlivened by similar complaints and has received answers from other users of Apple Watch Series 3, which also claims to be experiencing similar problems while in hospital.
Apple previously mentioned that pacemakers, defibrillators or other medical devices could affect components and radios at Apple Watch in charge of emitting electromagnetic waves.
Apple's answer does not specify the chances of the device being affected by the equipment used by the hospital. The solution Apple is trying to solve for this problem is to activate the Airplane mode while inside the hospital. However, doing so will prevent Apple Watch from connecting to the internet or mobile.