Pulse oximetry desaturation alarms on a general postoperative adult unit: a prospective observational study of nurse response time.

BACKGROUND: Continuous pulse oximetry monitoring is recommended to improve safety during postoperative opioid use, however concerns with monitoring on general care units remain, given potential system barriers to alarm transmission, recognition, and nursing response.
METHODS: This prospective, observational study evaluated unit and hospital-level factors affecting nurses' response to monitor desaturation alarms in postoperative patients on a general postoperative unit. With exemption and waiver of consent granted from the Institutional Review Board, monitoring data were downloaded from bedside monitors of postoperative patients. Alarm notification data and response times were recorded from the continuous capture of institutional surveillance data. Paging notifications were coded as clinically relevant (i.e., true oxygen desaturation with SpO2<89 for >15s) or irrelevant (i.e., artifact, inappropriate alarm threshold, or failure to delay page). Linear mixed models, and correlation coefficients were used to examine the relationships between unit staffing, shift, paging burden and response time. Means and [95% confidence intervals] are presented.
RESULTS: 1616 monitoring hours in 103 patients yielded 342 desaturation events (duration 23.6s [20.99, 26.1]) and 710 notification pages, 36% of which were for clinically relevant desaturation. Nursing response time was 52.1s [46.4, 57.7], which was longer at night (63.8 [51.2, 76.35]; p=0.035), but not related to unit staffing. Missed alarm events (i.e., no notification page transmitted) occurred for 26% of the clinically relevant events, and were associated with higher paging burden (p=0.04), lower SpO2 values (81.8 [80.5, 83.0] vs. 83.2 [82.6, 83.8]; p=0.026), and higher odds of intervention (OR 3.5 [1.38, 8.9]). 65% of patients with desaturation events received interventions which correlated with the number of pages (rho=0.422; p<0.01) and events (rho=0.57; p<0.01), desaturation duration (rho=0.505; p<0.01), and SpO2 (rho=-0.324; p<0.01).
CONCLUSIONS: One-third of pulse oximetry alarm notifications were for clinically relevant oxygen desaturation, facilitating timely nursing response and intervention for most patients. Unit staffing and false alarm frequency were not associated with response time, suggesting a high level of attention on this unit. The nature and degree of missed alarm events suggests patient safety concerns posed by hospital-level transmission systems warranting further strategies to ensure monitoring safety.