Exposure of the critically ill patient to extremely low-frequency electromagnetic fields in the intensive care environment

Abstract

Objective: To measure the electromagnetic emission of intensive care medical equipment, in order to assess whether a potentially dangerous magnetic flux is present around the patient, and to evaluate the exposure conditions of the patient to extremely-low-frequency electromagnetic fields (ELF EMF). Design: Descriptive study. Setting: Intensive care unit (ICU) at a general hospital. Measurement and results: The flux density of alternating (AC) 50-Hz, EMF was measured and mapped around electrical devices in a six-beds adult ICU furnished with standard equipment (ventilator, monitor, infusion pumps, heated airbed, humidifier). The overall flux density in the patient area was assessed by measuring the field intensity at the patient's head during the day and at night over 6 days. The magnetic flux density was not uniformly distributed around each device, being higher [up to 40 microTesla (μT)] close to fan motors and mains supply. In 83% of the patients a field intensity > 0.20 μT (safety limit) was detected. Conclusions: The ICU environment is at risk from electromagnetic pollution, the long stay patients and their 'day-long' exposure are additional risk factors. EMFs drop off as the distance from the equipment is increased, according to the inverse-square law, and the exposure risk may be minimized by keeping a safety distance from the EMF source. The actual value of that safety distance may be variable and depends on several factors: (1) type of equipment, (2) orientation of equipment, (3) equipment 'overcrowding' and (4) available space in each bed space. The magnetic flux density should be monitored regularly in every ICU for the specific design of each unit.