Radiofrequency transmission to monitoring devices in the operating room: a simulation study

We evaluated radiofrequency (RF) transmission to various monitoring devices using circuits that simulated potentially hazardous conditions for patients in the operating room. Right heart ejection fraction (REF) pulmonary artery catheters, transesophageal atrial pacing stethoscopes, and temperature-sensing esophageal stethoscopes were subjected to RF transmission from an electrosurgery unit. Peak voltage and spark intensity were measured in circuits between the electrocautery dispersive pad and conductive elements of the various medical devices. All monitoring devices with an exposed conductive surface were found to have induced voltages and even spark generation. The ranking for peak voltage from least to most was as follows: disrupted esophageal stethoscope (620 volts), the transesophageal pacemaker (640 volts), and the REF pulmonary artery catheter (PAC) (680 volts). Peak voltage measurements of the REF PAC significantly decreased from 388 +/- 23 to 142 +/- 22 volts (P < 0.0001, Student's t-tests) in a fluid medium compared to air. In a fluid medium, peak voltage significantly decreased from 142 +/- 22 to 85 +/- 15 volts (P < 0.0001, Student's t-tests) when the REF PAC was connected to the cardiopulmonary monitor.