Intraoperative Electromagnetic Navigation Bronchoscopy Interference With Cardiac Monitoring

Abstract

To the Editor: Electromagnetic navigation bronchoscopy (ENB) is indispensable for a robust thoracic oncology program. It allows for safe and effective sampling of peripheral lung nodules and transbronchial placement of fiducial markers to guide stereotactic body radiotherapy or surgical wedge resection.1 ENB is now routinely performed in hospitals around the world and has revolutionized care of lung cancer patients. In this letter, we present a case of intraoperative ENB interference with cardiac monitoring. The patient was scheduled for peripheral lung nodule tattoo placement to guide lung nodule wedge resection using the robotic assisted thoracoscopic surgery. The patient was sedated and intubated and remained hemodynamically stable. The patient was verified to be lying on the ENB board and the electrodes of the ENB (superDimension Inc., Minnesota, Plymouth, MN) were placed on the patient’s chest. The cardiac monitor alarmed and indicated asystole on the continuous electrocardiographic (EKG) monitoring. The patient’s pulse and blood pressure were stable, and the pulse oxymetry monitor indicated a heart rate of 78 per minute with good pulsatile flow. Troubleshooting the monitor wires did not solve the issue. Upon disconnecting The ENB board, we noticed an immediate return to normal sinus rhythm on the cardiac monitor. Connecting the board again led to asystole. The problem of electromagnetic interference (EMI) resolved by moving the EKG leads anteriorly on the patient’s chest and further away from the ENB board (Figs. 1, 2). The cardiac monitor (model: M1097AA02; Philips, Boeblingen GmbH Germany) was in excellent condition with no apparent damage and no previously reported malfunction.FIGURE 1: Cardiac monitor during ENB showing the rhythm converting from normal sinus to asystole. ENB indicates electromagnetic navigation bronchoscopy.FIGURE 2: The cardiac monitor showing the rhythm converting from normal sinus to asystole when the ENB under bed board was connected and back to normal sinus rhythm when the board is disconnected. ENB indicates electromagnetic navigation bronchoscopy.EMI with medical devices is a widely accepted dictum. EMI from mobile phones has been shown to affect pacemakers, defibrillators, and even mechanical ventilators.2 EMI generated through these devices can also interfere with EKG machines which can lead to unnecessary interventions and confusion. The ENB system (superDimension Inc.) consists of a planning software that converts computed tomographic images into 3-dimensional reconstruction and virtual bronchoscopy of the airways, an electromagnetic localization board/amplifier that generates a low frequency alternating voltage current, an extended working channel (EWC) similar to a guided sheath, a steerable navigation catheter and a “locatable guide” containing sensors that allow precise tracking of both position and orientation throughout the electromagnetic field.3 Sensor probes are used to navigate the bronchial tree and include 8 movable navigated pathway mechanisms. SuperDimension procedure screen showing 6 simultaneous views, bronchoscopy unit/screen, fluoroscopy equipment, patient monitoring equipment and the anesthesia machine are routinely used during the procedure. The location board is placed underneath the patient’s mattress ensuring that the region of interest is encompassed within an imaginary rectangular prism of magnetic field extending 50 cm above the location board.3 This board is 1 cm in thickness with the dimension of 47×56 cm2 and creates a magnetic field around the patient. The patients are placed in supine position on the localization board and 3 reference electrodes are placed on the anterior chest of the patient to enable precise tracking of the locatable guide through the electromagnetic field. Patient sensor triplets are adjusted on the patient to account for movement, inspiration, and expiration. Metal objects and/or electronic devices within one meter of the electromagnetic