Background: Vital sign monitors and ventilator/anesthesia workstations are equipped with multiple alarms to improve patient safety. A high number of false alarms can lead to a "crying wolf" phenomenon with consecutively ignored critical situations. Systematic data on alarm patterns and density in the perioperative phase are missing. Our objective of this study was to characterize the patterns of alarming of a commercially available patient monitor and a ventilator/anesthesia workstation during elective cardiac surgery.
Methods: We performed a prospective, observational study in 25 consecutive elective cardiac surgery patients. In all patients, identically fixed alarm settings were used. All incoming patient data and all alarms from the patient monitor and the anesthetic workstation were digitally recorded. Additionally, the anesthesia workplace was videotaped from 2 different angles to allow retrospective annotation and correlation of alarms with the clinical situation and assessment of the anesthesiologists' reaction to the alarms.
Results: Of the 8975 alarms, 7556 were hemodynamic alarms and 1419 were ventilatory alarms. For each procedure, 359 ± 158 alarms were recorded, representing a mean density of alarms of 1.2/minute.
Conclusion: Approximately 80% of the total 8975 alarms had no therapeutic consequences. Implementation of procedure-specific settings and optimization in artifact and technical alarm detection could improve patient surveillance and safety.