Advanced pulse oximeter signal processing technology compared to simple averaging. II. Effect on frequency of alarms in the postanesthesia care unit.
OBJECTIVE
To determine the effect of a new pulse oximeter (Nellcor Symphony N-3000, Pleasanton, CA) with signal processing technique (Oxismart) on the incidence of false alarms in the postanesthesia care unit (PACU).


METHODS
Prospective study.


METHODS
Nonuniversity hospital.


METHODS
603 consecutive ASA physical status I, II, and III patients recovering from general or regional anesthesia in the PACU.


METHODS
We compared the number of alarms produced by a recently developed "third"-generation pulse oximeter (Nellcor Symphony N-3000) with Oxismart signal processing technique and a conventional pulse oximeter (Criticare 504, Waukesha, WI). Patients were randomly assigned to either a Nellcor pulse oximeter or a Criticare with the signal averaging time set at either 12 or 21 seconds. For each patient the number of false (artifact) alarms was counted.


RESULTS
The Nellcor generated one false alarm in 199 patients and 36 (in 31 patients) "loss of pulse" alarms. The conventional pulse oximeter with the averaging time set at 12 seconds generated a total of 32 false alarms in 17 of 197 patients [compared with the Nellcor, relative risk (RR) 0.06, confidence interval (CI) 0.01 to 0.25] and a total of 172 "loss of pulse" alarms in 79 patients (RR 0.39, CI 0.28 to 0.55). The conventional pulse oximeter with the averaging time set at 21 seconds generated 12 false alarms in 11 of 207 patients (compared with the Nellcor, RR 0.09, CI 0.02 to 0.48) and a total of 204 "loss of pulse" alarms in 81 patients (RR 0.40, CI 0.28 to 0.56). The lower incidence of false alarms of the conventional pulse oximeter with the longest averaging time compared with the shorter averaging time did not reach statistical significance (false alarms RR 0.62, CI 0.3 to 1.27; "loss of pulse" alarms RR 0.98, CI 0.77 to 1.3).


CONCLUSIONS
To date, this is the first report of a pulse oximeter that produced almost no false alarms in the PACU.
Rheineck-Leyssius
A T
AT
Department of Anesthesiology, Twenteborg Hospital, Almelo, The Netherlands.
Kalkman
C J
CJ
D000762:Anesthesia Recovery Period; D016477:Artifacts; D005189:False Positive Reactions; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000628:therapy; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D010092:Oximetry; D011446:Prospective Studies; D011997:Recovery Room; D012815:Signal Processing, Computer-Assisted