Frequency of Clinical Alarms in Intensive Care Units and Nurses' Sensitivity to Them

An Observational Study

Burcu Ceylan, PhD, RN; Leyla Baran, PhD, RN; Ülkü Yapucu Güneş, PhD, RN


Am J Crit Care. 2021;30(3):186-192. 

In This Article


Of the 20 nurses included in the study, 82.5% were women, the mean (SD) age was 30.4 (3.5) years (range, 25–40 years), the mean amount of work experience was 7.4 (3.8) years, the mean amount of experience working in the ICU was 5.4 (2.7) years, and the mean number of work hours per week was 45.2 (4.6).

Among the patients observed, 98.8% were being monitored and 17.5% were connected to a pulse oximeter, 35% to a mechanical ventilator, 81.3% to a fluid infusion pump, and 30% to an enteral feeding pump. Only 5 patients had all the devices connected simultaneously; the patients connected to mechanical ventilators were mostly connected both to bedside monitors and to fluid infusion pumps or enteral feeding pumps.

The total mean number of alarms by ICU and shift is shown in Table 1. When we assessed all of the ICUs together, we found that the total mean (SD) number of alarms sounding per hour per bed was 1.9 (1.4) during the 8 AM to 4 PM work shift and 1.7 (1.1) during the 4 PM to 8 AM work shift (Table 1). The highest total mean number of alarms per hour was in the anesthesiology and reanimation unit (2.50 [1.40]); the lowest was in the internal medicine unit (1.30 [0.92]). The differences in the total mean number of alarms sounding per hour across the various ICUs were statistically significant (P = .003). When we evaluated all of the ICUs together, we found that the mean frequency of an alarm sounding per hour per bed was 1.8. Considering that each ICU has a mean of 12 beds, the mean number of alarms sounding in an ICU in the course of an hour was 21.6. If it is assumed that a nurse is responsible for 4 patients, it follows that nurses were exposed to and required to respond to 7.2 alarms per hour.

Throughout the observation period (80 hours), in all of the ICUs together there were 144 alarms, of which 102 (70.8%) were valid, 22 (15.3%) were false, and 20 (13.9%) were technical. Many of the valid alarms were critical; all of the false and technical alarms were considered noncritical. All of the technical alarms originated from a monitor whose electrocardiogram probes, blood pressure sleeve, or oxygen saturation probe had not been connected to the patient. The false alarms stemmed from a pulse oximeter or bedside monitor. The nurses did not respond to 38.2% of the 102 valid alarms, 40.9% of the 22 false alarms, and 77.8% of the 20 technical alarms (data not shown).

Assessment of the mean duration of activation of the alarms per hour showed that valid alarms were active for a mean of 8 minutes (range, 1–25 minutes), false alarms for 14 minutes (range, 1–35 minutes), and technical alarms for 53 minutes (range, 5–60 minutes). Thus, the technical alarms were sounding almost continuously.

The distribution of nurses' responses to valid alarms according to type of device emitting the alarm during the 1-hour observation period is shown in Table 2. In the 1 hour of observation, more than 1 alarm sounded. Because each alarm sounded from a different device and for a different reason and the nurse's response was different for each alarm, all of these variables cannot be combined into a single data value. The number of alarms from first to fifth here represents the alarm sounded by any one of the devices connected to a patient cared for by the nurse during the 1-hour observation period. The first alarm represents the nurse's first exposure to any of the alarms coming from any of the devices the patient was connected to; the second, third, fourth, or fifth alarm could be from the same alarm and patient or from a different patient and alarm. The data therefore indicate the nurse's responses to the alarms sounded during that 1 hour of observation.

The mean number of alarms sounding in an ICU in the course of 1 hour was 21.6.

Of the valid alarms, 51% were emitted from the bedside monitor. More than half of the alarms emitted from the bedside monitor received no response from the nurse. In examining the reasons for the alarms emitted from the bedside monitor, we found that they were due to high mean blood pressure, low or high systolic or diastolic blood pressure, low oxygen saturation, bradycardia, or tachycardia. The nurse generally implemented an intervention in response to the alarms emitted by the enteral feeding pump or the pulse oximeter (Table 2).