Minimizing interference and false alarms from electrocautery in the Nellcor N-100 pulse oximeter.

Because the Nellcor N-100 pulse oximeter is generally quite sensitive to electrocautery interference, erroneous oxygen saturation values may be displayed and an audible false alarm may sound. We have discovered, through trial and error, several techniques that may minimize both the interference and the false alarms. Keeping the pulse oximeter sensor and the oximeter unit as far as possible from the surgical site and the electrocautery grounding plate will usually decrease the interference. If this step is inadequate, the incidence of false alarms can be decreased by setting the high pulse rate alarm to approximately 160, operating the unit in mode 2 (the rapid-response mode), and setting the "alarm off" function to 120 seconds. These steps will usually markedly decrease the incidence of false alarms.