Figure 1.
Physiologic monitor device in Intensive Care Unit.
Bedside patient monitor (GE Healthcare, Milwaukee, WI) displays multiple physiologic waveforms and vital sign measurements. The nurse pictured here gave written informed consent to publish this photograph supplied by the San Francisco Chronicle newspaper (with permission) for their story on alarm fatigue at: http://www.sfgate.com/health/article/Hospitals-look-to-reduce-danger-of-alarm-fatigue-4918018.php.
Table 1.
UCSF Alarm Study Units.
Figure 2.
Hospital infrastructure to automatically store all physiologic monitor waveform and alarm data.
Figure 3.
Patient monitoring ECG lead configuration.
A 5-electrode lead configuration was used in all study ICUs with Mason-Likar electrode placement of the limb leads on the torso and one chest electrode that is routinely placed in the V1 location.
Table 2.
Alarm Default Settings for Adult ICUs during the Study Period.
Table 3.
Alarm Annotation Protocol.
Figure 4.
True positive ventricular tachycardia alarm using seven available ECG leads for diagnosis.
Page one of the alarm annotation analysis tool shows a 10-second rhythm strip of all seven available ECG leads at the time that a ventricular tachycardia alarm was triggered. In this and subsequent Figures, ECG Leads are displayed from top to bottom in the following sequence: Lead I, II, III, V (typically V1), aVR, aVL, aVF. As evident at the beginning of the rhythm strip, the patient has an underlying rhythm of atrial fibrillation with a rapid ventricular rate of about 140. There is an isolated ventricular premature beat (4th beat from the end) and its QRS morphology is identical to the initial beat of the alarm event. Knowing that the event is initiated by a ventricular ectopic beat provides strong evidence that this event is a true ventricular tachycardia alarm.
Figure 5.
True positive ventricular tachycardia alarm using non-ECG waveforms for diagnosis.
Page 2 of the alarm annotation analysis tool depicts the same alarm event as in Figure 4 with all available non-ECG waveforms. Additional proof that this is a true ventricular tachycardia alarm is provided by observing cessation of the arterial blood pressure waveform that falls to near zero during the arrhythmia.
Figure 6.
False positive ventricular tachycardia alarm using seven available ECG leads for diagnosis.
Page one of the alarm annotation analysis tool in a second patient with a ventricular tachycardia alarm. Proof that this is a false positive alarm is provided by observing Lead III that shows clearly-visible P-QRS-T waveforms indicating normal sinus rhythm. All six remaining ECG leads show artifact that mimics ventricular tachycardia. It is important to point out that Lead III is not one of the two leads routinely displayed on the bedside monitor in our ICUs so unless all available leads are reviewed, a misdiagnosis would be made of rapid polymorphic ventricular tachycardia. This type of rapid, repetitive artifact on the ECG is often created during patient monitoring by motion artifact during activities of daily living. The non-artifact lead (Lead III) uses the left arm and left leg electrodes but not the right arm electrode. So, this is likely to be a right-handed patient doing something like brushing teeth.
Figure 7.
False positive ventricular tachycardia alarm using non-ECG waveforms for diagnosis.
Page 2 of the alarm annotation analysis tool depicts the same alarm event as in Figure 6 showing all available non-ECG waveforms. Additional proof that this is a false ventricular tachycardia alarm is provided by the following: a.) no change in the arterial pressure waveform during the event, b.) arterial waveform pulsations match the normal sinus rhythm rate, and c.) SpO2 waveform pulsations match the normal sinus rhythm rate. Of interest, the same artifact that contaminates the ECG signal also contaminates the respiratory waveform, as evidenced by an erroneous device-measured respiratory rate of 162 breaths per minute.
Table 4.
Schema for Counting and Reporting Physiologic Monitor Device Alarms.
Figure 8.
Frequency of all unique alarms (N = 2,558,760) over a 31-day period.
Figure 9.
False apnea alarm in a patient breathing adequately on mechanical ventilation.
The respiratory waveform (bottom tracing labelled “Resp”) has a flat line appearance. The detection of respirations from the ECG lead (impedance method) is inaccurate in this patient, displaying an erroneous respiratory rate of 4 per minute.
Table 5.
ST-Segment Alarm Durations in a 16-Bed Cardiac ICU.
Table 6.
Accuracy of 12,671 Arrhythmia Alarms.
Figure 10.
False alarm with one non-artifact ECG lead that confirms artifact mimicking ventricular fibrillation.
Six of the seven ECG leads show what looks like a rapid (>400) polymorphic ventricular arrhythmia. However, Lead II clearly shows sinus rhythm at a rate of 94. Without this single non-artifact lead, a misdiagnosis would be made of ventricular fibrillation.
Figure 11.
False accelerated ventricular rhythm alarm in a patient with left bundle branch block.
Sinus rhythm at a rate in the 60′s is evident by observing P waves preceding each QRS complex with a consistent PR interval. P waves are visible in all seven leads (especially clear-cut in Leads I and II).
Figure 12.
True accelerated ventricular rhythm alarm showing why this arrhythmia is not considered an “actionable” alarm condition.
Accelerated ventricular rhythm at a rate of 56 for the first 5 beats followed by 2 fusion beats; the last 2 beats are normal sinus rhythm. The invasive arterial pressure waveform (bottom tracing) shows no change between normal rhythm and accelerated ventricular rhythm which confirms the rationale for the published guidelines stating no treatment is indicated for this arrhythmia in hospital settings [5].
Figure 13.
False accelerated ventricular rhythm alarm in a patient with ventricular pacing.
Patient with atrial fibrillation and intermittent ventricular pacing does not have PaceMode activated. As a result, a period of ventricular pacing goes undetected by the algorithm (no pacemaker spikes are “painted” in) and a false alarm is generated of accelerated ventricular rhythm. The investigators determined this to be intermittent pacing (rather than accelerated ventricular rhythm) because the rate matched the pacemaker heart rate setting. Moreover, the QRS morphology across all 7 leads matched the QRS morphology of corresponding leads on a hospital-acquired standard “diagnostic” 12-lead ECG during a known period of pacing.
Figure 14.
Low amplitude QRS in a patient with an excessive number of alarms.
Standard “diagnostic” 12-lead ECG recorded from the patient who contributed nearly half of the 12,671 arrhythmia alarms for annotation. The ECG shows left bundle branch block with low amplitude QRS complexes in the limb leads but not in the V leads. Since one of the available leads acquired with the physiologic patient monitoring device is a V lead, the arrhythmia algorithm could have avoided the excessive number of false alarms had all available leads been used for QRS detection.
Table 7.
Frequency of Visible QRS Complexes in One or More ECG Leads during False Brady-Arrhythmia Alarms.
Figure 15.
ECG signal quality in 12,671 annotated arrhythmia alarms.
Good signal quality (green) was defined as a clearly visible P-QRS-T waveform across all available leads with little to no noise, baseline wander, or leads off. Fair signal quality (yellow) was defined as moderate noise or baseline wander but having identifiable QRS complexes for basic rhythm/rate detection. Poor signal quality (red) was defined as being unanalyzable because of excessive noise, baseline wander or leads off.
Figure 16.
Electrode failure causing artifact and a false ventricular tachycardia alarm.
Electrocardiogram in 6 of the 7 available leads shows intermittent loss of signal (signal “squares off” on top and bottom of tracing) due to an electrode problem such as loss of skin contact or dried out electrode gel. One ECG lead (Lead II that uses the right arm and left leg electrodes) does not show electrode failure so the likely electrode that is malfunctioning is the left arm electrode. Failure to apply fresh electrodes in this case will result in numerous false alarms.
Table 8.
Comparison of Annotated Arrhythmia Alarm ICU Databases.
Table 9.
Key Insights into the Problem of Alarm Fatigue and Recommendations.