Design and Evaluation of a Wireless Electrocardiogram Monitor in an Operating Room: A Pilot Study

BACKGROUND: Wired electrocardiogram monitors are an important component of current perioperative monitoring. Wireless monitoring units could help reduce the number of cables attached to patients and thus improve anesthesia ergonomics and patient management. However, there is concern that electromagnetic interference generated by electrosurgical units may prevent effective wireless signals in the operating room. To evaluate the extent of this problem, we developed a Bluetooth electrocardiogram prototype monitor and compared its electrocardiogram traces to those captured with a standard wired electrocardiogram monitor in our operating room. METHODS: Bluetooth electrocardiogram and standard electrocardiogram traces captured from 10 patients undergoing surgical procedures that required use of an electrosurgical unit were compared by analysis of the durations of the P wave, QRS complex, and T wave and the position of the ST segment from the isoelectric line. The impact of the electrosurgical units on the Bluetooth electrocardiogram and S-electrocardiogram recordings was also assessed. RESULTS: There were no clinically relevant differences in P wave, QRS complex, or T-wave durations (0.006, 0.004, and 0.017 seconds, respectively) between Bluetooth electrocardiogram and standard electrocardiogram or in the position of the ST segment from the isoelectric line (0.02 mV). Mean differences were near zero, and Bland-Altman limits of agreement for individual differences were narrow (-0.035 to 0.047, -0.03 to 0.038, and -0.112 to 0.078 seconds for P wave, QRS complex, and T-wave durations, respectively, and -0.13 to 0.17 mV for ST segment position). Electrosurgical units use electrically disrupted Bluetooth electrocardiogram and standard electrocardiogram signals, but there was no electromagnetic interference effect on the Bluetooth electrocardiogram signals. CONCLUSIONS: Wireless electrocardiogram using Bluetooth can be reliably used in the operating room. The electrosurgical unit induces electric rather than electromagnetic artifacts, thus affecting wired and wireless electrocardiogram in a similar fashion.