Brief Reports
ALARMED: Adverse events in Low-risk patients with chest pain Receiving continuous electrocardiographic Monitoring in the Emergency Department. A pilot study

Presented at the Canadian Association of Emergency Physicians (CAEP) Annual Scientific Meeting in Montreal, April 2004.
https://doi.org/10.1016/j.ajem.2005.05.015Get rights and content

Abstract

Objectives

Current guidelines suggest that most patients who present to an emergency department (ED) with chest pain should be placed on a continuous electrocardiographic monitoring (CEM) device. We evaluated the utility of CEM in ED patients with chest pain.

Methods

We enrolled stable patients who presented to a single ED with chest pain suspected to be ischemic in origin and who were placed on CEM. Patients were classified according to risk of poor outcome using 3 published stratification tools. Trained observers prospectively recorded number of monitored hours, alarms, changes in management, and monitor-detected adverse events (AEs). The primary outcome measure was the rate of AEs detected by CEM. Secondary outcome measures were the rate of alarms that resulted in a change in management and number of false alarms.

Results

We enrolled 72 patients, 56% of whom were categorized as very low-risk by Goldman risk criteria. During 371 monitored hours, we recorded 1762 alarms or 4.7 alarms per monitored hour. There were 11 AEs (0.68%; 95% CI, 0.35%-1.2%), 3 of which resulted in a change in management (0.2%; 95% CI, 0.04%-0.5%). Seven AEs were bradydysrhythmias with a heart rate of 45 or higher; the eighth patient had no change in symptoms and was given atropine for a heart rate of 32. The other 3 AEs were an untreated supraventricular tachycardia, a brief sinus pause that triggered a rate change in intravenous nitroglycerin by the patient's nurse, and a run of premature ventricular contractions after which heparin was administered. None of the 3 patients with a change in management was categorized as the lowest-risk.

Conclusions

Routine CEM in low-risk ED patients with chest pain results in an excessive number of alarms, most of which require no change in management. In these patients, the benefit of CEM may be limited, and given that 99.4% of alarms were false, current CEM technology needs to be improved.

Introduction

Currently in the United States and Canada, most patients who present to an ED with chest pain are placed on a continuous electrocardiographic (ECG) monitor (ie, a telemetry monitor). Because of an increased risk of a fatal arrhythmia in patients experiencing an acute myocardial infarction [1], [2] and the effectiveness of early defibrillation for dysrhythmia termination [3], both the American Heart Association and the Canadian Association of Emergency Physicians stipulate that patients with chest pain that could be due to ischemia be placed on continuous ECG monitoring (CEM) [4], [5]. These guidelines are based on expert opinion, as there are no published clinical trials on monitoring for “rule-out myocardial infarction” patients in the ED [4], [5]. Several studies have questioned the use of CEM in admitted patients with chest pain [6], citing negligible rates of adverse events (AEs) in “very low-risk” patients in particular [7], [8], [9]. ED patients with chest pain are significantly different from their admitted counterparts because (1) if they are suffering an acute coronary syndrome (ACS), they are at a significantly higher risk of having an AE early in the course of their disease when they are in the ED [10], and (2) because the majority (more than 80%) of these patients are not actually experiencing an ACS [11], this dilutes the number of AEs in the ED chest pain patient population. Approximately 70% of ED patients with chest pain have no ACS nor an AE [12]. Although studies of continuous ST-segment monitoring have been conducted in ED patients [13], currently, most EDs do not use this technology [4], and no study has evaluated the use of standard CEM in ED patients with chest pain.

ED crowding is worsening [14], [15], and because patients with chest pain are subject to these forces [16], the availability of monitored beds for these patients has decreased. If all patients with cardiac-related chest pain, including low-risk patients, use CEM, sicker patients who will yield a greater benefit may be denied the technology because of a limited number of monitors [7], [16]. In addition, ED crowding is exacerbated by time spent in the ED awaiting a monitored ward bed [17], and monitoring carries a financial burden through increased nursing time and equipment costs [14]. These monitors could be allocated more efficiently if emergency physicians (EPs) could reliably identify a subgroup of patients with chest pain with a very low risk of having a monitor-signaled AE. We suspect that in the current practice environment, EPs are frequently faced with fully occupied ED monitors and are using their clinical judgment to decide which patients to remove from monitoring when a higher acuity patient arrives. In this situation in particular, evidence-based criteria for monitor removal would be very useful.

We conducted this pilot study to test the feasibility of a large, prospective, observational study on the utility of CEM in ED patients with chest pain. In this descriptive study, we determined the rate of AEs detected by CEM, the rate of change in management that occurred secondary to alarms, and the rate of false alarms that occurred during CEM.

Section snippets

Study design

We conducted a prospective, observational cohort study of patients with chest pain who were placed on CEM in the ED from June to August 2003. Care was directed by the managing physician and was not influenced by the study. Subjects were enrolled consecutively from 11:00 until 23:00, Monday to Friday. The protocols were reviewed and approved by the hospital research ethics board.

Setting

The study took place at Mount Sinai Hospital in Toronto, Ontario, a tertiary care teaching hospital ED with an annual

Results

We identified 86 patients who were eligible for study enrolment. Thirteen patients refused consent or were unable to consent because of a language barrier. Another patient left against medical advice before consent. Thus, we enrolled 72 patients; patient characteristics are presented in Table 2. One enrolled patient had insufficient data collected to characterize his risk with the stratification tools. Using triage logs, we identified 1 eligible patient who was missed for enrolment.

On initial

Discussion

The utility of CEM among patients admitted to hospital for known or potential ischemic heart disease has been questioned because of the low rate of AEs identified by the technology [5], [6], [7], [15]. Our study reached a similar conclusion among ED patients with chest pain. This small, prospective study found that only 0.62% of CEM alarms were sounded because of an AE, none of which were hemodynamically significant, and only 0.2% resulted in a change in management. This is despite a

Conclusions

The use of CEM in patients with chest pain in the ED may be of limited value, both because of a low rate of monitor-signaled AEs and in the high number of false alarms. This resource appears to be very inefficient in its current role: given that 99.4% of alarms were false, current CEM technology needs to be improved. A large prospective study is warranted to further evaluate the utility of this resource in ED low-risk patients with chest pain.

Acknowledgment

The authors thank Michelle Loftus, research coordinator, for her valuable research assistance.

References (19)

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