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Cardiology |
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Challenges associated with continuous 12-lead ECG monitoring in critically ill patients admitted for non-cardiac conditions
Booker KJ*, Drew BJ and Holm K*
Loyola University Chicago* and University of California
San Francisco, USA
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Preliminary communication
Critically ill patients present challenges to continuous 12-lead ECG monitoring. Vital data reflective of ischemia and arrhythmias are obtained, but potential for motion artifact associated with interventions, difficulties with lead placement due to dressings, lead adherence problems, and frequent on and off-unit testing are but a few of the challenges in obtaining continuous, accurate signal monitoring.
The purpose of this analysis was to determine the frequency and types of signal interruptions as a secondary analysis in a study designed to detect the relationship between myocardial ischemia and acuity of critical illness in medical-surgical critically ill patients.
| Study Purpose |
| To determine the frequency and types of signal interruptions using 12 lead ECG monitoring in critically ill non-cardiac patients during the first 48 hours of ICU stay |
Methods
A total of 104 patients were enrolled at two community hospitals in the Midwest over a five-month period beginning June 2000. Continuous 12-lead ECG monitoring (Datex-Ohmeda S/5 Telemetry System, available in US and Canada only) was performed for 48 hours or until discharge from the ICU. Positional ECGs were obtained for head of bed (HOB) flat, HOB elevation 45 degrees, right and left side lying positions whenever patient's condition allowed.
| Study Design |
| Secondary analysis from an ongoing prospective study to determine the relationship between transient myocardial ischemia and patient acuity, troponin I levels, cardiac complications, and length of ICU and hospital stay |
The ECG monitoring system stores continuous 12 lead ECGs for 72 hours. All patient tracings were reviewed daily. The amount and cause of monitoring interruptions, off-unit testing, or surgeries that necessitated removal of the monitoring system and amount of artifact was documented.
| Patient selection |
Included: Excluded: |
Findings
The 104 patients were monitored for a total of 3613 hours (mean 34.7 hours/patient), and 42 patients (40%) had excellent quality tracings, with no interruptions in monitoring. Interruptions included
152.7 hours of artifact of unknown cause, 37.4 hours for off-unit testing/surgery and 34.3 hours for technical problems. In addition, several unique situations occurred which will be reported.
| Number of cases | Special observations |
| 1 | Tracings indicated switch of LBBB to RBBB. Further inspection: limb and precordial lead wire reversal with mirror image tracings of V1/V6, V2/V5 and limb leads. |
| 2 | Leads V3 & V4 were inaccurately placed due to defibrillator pads on the chest. This caused inconsistent lead placement for 24 hrs in the affected leads. |
| 2 | Extreme diaphoresis caused displacement of electrodes and periods that could not be analyzed. |
| 1 | There was a severe respiratory artifact due to respiratory failure for most of the monitoring period (i.e. for 30 of 38 monitored hours) |
| 1 | Tracings had poor quality due to severe tremor from Parkinson's disease |
| 2 | Extreme confusion resulted in repeated removal of electrodes by patient forcing termination of monitoring |
| 1 | Power line 60 Hz interference obscured tracings in leads I, II and aVR for several hrs |
| Additional findings |
| Of 76 patients who remained in the study for 24 hrs, eight (10.5%) developed transient ischemia (total 37 events, 86% ST depressions) |
| Twelve patients (15.8%) developed elevated troponin I levels, identical to Guest et al (1995) study of medical/respiratory ICU patients |
| Most ischemic events were detected in two or more leads; V5 and lead II were most sensitive |
Conclusions
In general, critically ill patients present unique challenges due to the critical nature of physiological processes and multiple demands placed on these patients. However, most ECG signals obtained were of excellent quality with minimal artifact.
| Summary |
| Continuous 12 lead ECG ST monitoring is feasible in critically ill patients. With careful skin prep, the vast majority of monitoring hrs (94%) have excellent quality |
| Most patients do not report discomfort despite placement of additional electrodes; nurses do express concern on patient's behalf |
| Consistent precordial electrode placement is challenging in some high-acuity patients and is expected to be more frequent in clinical practice without researcher involvement |
Literature
See the More
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(ed.)
Last updated: 1 September 2001Created |
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