Inappropriate dispatcher decision for emergency medical service ...

American Journal of Emergency Medicine (2011) 29, 37–42

www.elsevier.com/locate/ajem

Original Contribution

Inappropriate dispatcher decision for emergency medical service users with acute myocardial infarction☆ Magali Fourny MSc a , Anne-Sophie Lucas MDb , Loïc Belle MDc , Guillaume Debaty MDb , Pierre Casez MSc a , Hélène Bouvaist MD d , Patrice François MD, PhD a,e , Gérald Vanzetto MD, PhD d , José Labarère MD a,e,⁎ a

Quality of Care Unit, Grenoble University Hospital, Grenoble, France Service d'Aide Médicale Urgente (SAMU 38), Grenoble University Hospital, Grenoble, France c Department of Cardiology, Annecy General Hospital, Annecy, France d Cardiovascular and Thoracic Department, Grenoble University Hospital, Grenoble, France e Techniques de l'Ingénierie Médicale et de la Complexité (TIMC), Unité Mixte de Recherche 5525, Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier, Grenoble, France b

Received 4 June 2009; revised 10 July 2009; accepted 11 July 2009

Abstract Objectives: Current guidelines recommend utilization of prehospital emergency medical services (EMSs) by patients with ST-elevation myocardial infarction (STEMI). The aims of this study were to estimate the percentage of inappropriate initial dispatcher decisions and determine their impact on delays in reperfusion therapy for EMS users with STEMI. Methods: As part of a prospective regional registry of patients with STEMI, we analyzed the original data for 245 patients who called a university hospital-affiliated EMS call center in France. The primary study outcome was time to reperfusion therapy calculated from the documented date and time of the first patient call. Results: The initial EMS dispatcher's decision was appropriate (ie, dispatching a mobile intensive care unit staffed by an emergency or critical care physician) for 171 (70%) patients and inappropriate for 74 (30%) patients. Inappropriate decisions included referring the patient to a family physician (n = 59), providing medical advice (n = 9), and dispatching an ambulance (n = 6). Inappropriate initial decisions resulted in increased median time to reperfusion for 140 patients receiving fibrinolysis (95 vs 53 minutes; P b .001) and 91 patients undergoing primary percutaneous coronary intervention (170 vs 107 minutes; P b .001). In-hospital mortality was not different between the 2 study groups (6.8% vs 9.9%; P = .42). Conclusion: The initial dispatcher's decision is inappropriate for 30% of EMS users with STEMI and results in substantial delays in time to reperfusion therapy. Accuracy of telephone triage should be improved for patients who activate EMSs in response to symptoms suggestive of acute coronary syndrome. © 2011 Elsevier Inc. All rights reserved.

☆

Grant support: This study was supported by a grant from Grenoble University Hospital (Direction de la Recherche Clinique, Programme de Recherche Clinique). ⁎ Corresponding author. Unité d'Evaluation Médicale, CHU Grenoble BP 217, 38 043 Grenoble Cedex 9, France. Tel.: +33 4 76 76 87 67; fax: +33 4 76 76 88 31. E-mail addresses: [email protected], [email protected] (J. Labarère). 0735-6757/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.ajem.2009.07.008

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1. Introduction

2.3. Study population

Prompt reperfusion therapy with either fibrinolysis or primary percutaneous coronary intervention (PCI) reduces mortality and morbidity for patients with ST-elevation myocardial infarction (STEMI) [1-4]. Current guidelines recommend utilization of emergency medical services (EMSs) by patients with STEMI to keep total ischemic time within 120 minutes from symptom onset to reperfusion [5]. Potential benefits of EMS utilization include early diagnosis and treatment with the use of prehospital 12-lead electrocardiography [6,7], prehospital fibrinolysis [8,9], activation of the catheterization laboratory en route [10,11], and management of life-threatening complications such as arrhythmias during transportation [10,12]. Many studies have investigated the reasons for delay in seeking treatment and EMS underutilization by patients with STEMI [13-16]. In contrast, limited data exist on the frequency of inappropriate decisions made by dispatchers and their consequences for these patients [17-19]. In this study, we aimed to determine the percentage of inappropriate initial EMS call center decisions for patients with STEMI. A secondary objective was to examine the impact of inappropriate initial EMS decisions on delays in reperfusion therapy and mortality.

Physicians at emergency departments and mobile intensive care units (SMUR) recruited patients 24 hours a day, 7 days a week between October 2002 and December 2004. Patients 18 years or older were eligible if they presented within 12 hours after the onset of symptoms suggestive of myocardial infarction (chest pain lasting for more than 20 minutes and not responsive to nitrates) with evidence of ST-segment elevation of at least 1 mm in 2 or more limb leads, ST-segment elevation of at least 2 mm in 2 or more precordial leads, or new or presumed new left bundle branch block. Although the registry included both EMSs and selftransported patients with STEMI, the present analysis focused on the subset of patients who called the Grenoble University Hospital–affiliated EMS call center (SAMU 38). To avoid confounding by a prehospital health care provider, our analytical sample was restricted to the patients for whom the call was placed by the patient or his/her relative.

2. Methods 2.1. Study design We analyzed the original data for prehospital EMS users who were enrolled in a regional prospective registry of patients with STEMI in the Northern Alps in France. The data collection methods, verification procedures, accuracy, and primary outcomes of this registry have been reported in detail elsewhere [20-22].

2.2. Setting As part of the French EMS [23], 3 call centers (Service d'Aide Médicale Urgente [SAMU]) and 12 mobile emergency care units (Service Mobile d'Urgence et Réanimation [SMUR]) are disseminated throughout the Northern Alps. Patients dial 15 to contact the call center. Using standardized clinical algorithms and local protocols, a physician handles the call by providing medical advice, referring the patient to a general practitioner, or dispatching an ambulance or a mobile intensive care unit (SMUR) [23,24]. Mobile intensive care units are staffed by emergency or critical care physicians who may administer prehospital fibrinolysis or activate the catheterization laboratory en route for primary PCI [25,26]. Mobile intensive care units and EMS call centers are affiliated with hospitals.

2.4. Data collection For each patient, the attending physician prospectively collected baseline characteristics, initial EMS decision, reperfusion therapy, and EMS response using a case report form. The initial EMS dispatcher's decision was coded as appropriate vs inappropriate. An appropriate initial decision was defined as an immediate decision to dispatch a mobile intensive care unit. Conversely, an inappropriate initial decision was defined as providing medical advice, referring the patient to a general practitioner, or dispatching an ambulance. The number of calls a patient placed before receiving an appropriate decision was also recorded. Reperfusion therapy was defined as receiving either fibrinolysis or PCI as a primary reperfusion strategy within 12 hours of the mobile intensive care unit's arrival on the scene. Although expeditious reperfusion therapy was advocated by our EMS guideline, physicians in charge of patients ordered fibrinolysis or primary PCI autonomously in this observational study [20].

2.5. Outcomes Our primary outcome was time to reperfusion therapy. Delay in EMS response (call to on scene time) was calculated from the documented date and time of the first patient call to the date and time that the mobile intensive care unit arrived on the scene. Time to fibrinolysis was calculated from the first patient call to needle. Time to primary PCI was calculated from the first patient call to the first balloon inflation. Our secondary outcome was inhospital mortality.

EMS triage of acute myocardial infarction

39

2.6. Statistical analysis Categorical variables were expressed as frequency and percentage, and continuous variables were presented as the median and interquartile range (IQR). Baseline characteristics, delays in reperfusion therapy, and in-hospital mortality were compared for patients receiving an appropriate vs an inappropriate initial decision using χ2 or Fisher exact tests for categorical variables and Wilcoxon rank sum test for continuous variables. We performed logistic regression to estimate the adjusted odds ratios of baseline characteristics associated with an inappropriate initial decision. Independent variables entered into the model included age, sex, chest pain duration,

Fig. 1

history of coronary artery disease, prior PCI, prior coronary artery bypass surgery, off-hour (weekdays 7 PM-7 AM and weekends) vs regular hour (weekdays 7 AM-7 PM) call, and distance from the PCI facility. Two-sided P values of less than .05 were considered statistically significant. Analyses were performed using Stata 9.0 (Stata Corp, College Station, TX).

3. Results Overall, 389 patients with STEMI were transported by mobile intensive care units after calling the Grenoble

Flow chart of patient enrollment.

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M. Fourny et al.

University Hospital–affiliated EMS call center (Fig. 1). The call was placed by a health care provider for 144 patients, including 141 (98%) patients for whom an appropriate decision to dispatch a mobile intensive care unit was made. Finally, our analytical sample consisted of 245 EMStransported patients for whom the call was placed by the patient or a relative. The median age for all patients was 63 years (IQR, 5172 years), 176 (72%) were men, and 42 (17%) had a prior history of coronary artery disease. The median chest pain duration was 45 minutes (IQR, 18-105 minutes) and the call was placed during off-hours for 164 (67%) patients. The initial EMS dispatcher's decision was inappropriate for 74 (30%) patients (95% confidence interval, 24%-36%), consisting of referring the patient to a family physician (n = 59), providing medical advice (n = 9), and dispatching an ambulance (n = 6). The number of calls placed before receiving an appropriate decision to dispatch a mobile intensive care unit was 2 for 67 patients, 3 for 6 patients, and 4 for 1 patient. No baseline characteristic was associated with an inappropriate initial decision in univariable (Table 1) and multivariable (Table 2) analyses. The percentages of patients receiving reperfusion therapy did not differ between the 2 study groups, and most of them received prehospital fibrinolysis (Table 3). Because of a longer EMS response time, an inappropriate initial decision resulted in median times to reperfusion increasing by 42 minutes for patients receiving fibrinolysis and 63 minutes for

Table 2 Adjusted odds ratios of baseline characteristics associated with inappropriate dispatcher decision for patients with STEMI Characteristics a

Adjusted odds ratio (95% confidence interval)

Age ≥75 y Male sex Chest pain duration b3 h History of coronary artery disease Prior PCI Prior coronary artery bypass surgery Off-hours call Distance from PCI facility 0-14 km 15-29 km ≥30 km

0.93 (0.45-1.90) 0.64 (0.34-1.22) 0.67 (0.29-1.54) 0.69 (0.17-2.74) 0.38 (0.05-2.77) 1.42 (0.16-12.26)

patients undergoing primary PCI (Table 3). In-hospital mortality did not differ according to the appropriateness of the initial dispatcher's decision.

Table 3 Comparison of reperfusion therapy, delays, and inhospital mortality for patients with STEMI receiving an appropriate vs inappropriate initial dispatcher decision Outcomes

Initial dispatcher decision

P

Appropriate Inappropriate (n = 171) (n = 74) Age ≥75 y Male sex Chest pain duration b3 h History of coronary artery disease Prior PCI Prior coronary artery bypass surgery Off-hours call Distance from PCI facility 0-14 km 15-29 km ≥30 km Anterior myocardial infarction Left bundle branch block Cardiogenic shock

39 129 149 34

(22.8) (75.4) (87.1) (19.9)

17 (23.0) 47 (63.5) 61 (82.4) 8 (10.8)

.98 .06 .31 .08

19 (11.1) 6 (3.5)

3 (4.1) 2 (2.7)

.08 .99

111 (64.9)

53 (71.6)

.31 .70

101 23 47 65

41 (55.4) 13 (17.6) 20 (27.0) 24 (32.4)

.40

2 (2.7) 2 (2.7)

.99 .99

(59.1) (13.4) (27.5) (38.0)

5 (2.9) 4 (2.3)

Values are presented as no. (%). a Values were missing for chest pain duration in 6 patients and offhours call in 5 patients.

1.00 1.38 (0.62-3.08) 1.14 (0.58-2.23)

a Six patients were excluded from multivariable analysis because of missing values for 1 or more covariates.

Table 1 Comparison of baseline characteristics for patients with STEMI receiving appropriate vs inappropriate initial dispatcher decision Characteristics a

1.05 (0.55-2.01)

Initial dispatcher decision Appropriate (n = 171)

Inappropriate (n = 74)

Reperfusion therapy, no. (%) 102 (59.7) 38 (51.4) Fibrinolysis a Primary PCI 62 (36.2) 29 (39.2) None 7 (4.1) 7 (9.4) Time from call to 53 (46-70) 95 (83-115) fibrinolysis, median (IQR), min b First call to on scene 28 (20-37) 71 (58-95) (EMS response time) On scene to fibrinolysis 24 (15-35) 22 (15-35) Time from call to PCI, 107 (85-146) 170 (126-199) median (IQR), min b First call to on scene 25 (20-38) 79 (63-101) (EMS response time) On scene to PCI 80 (56-113) 66 (55-101) In-hospital mortality, 17 (9.9) 5 (6.8) no. (%) a

P

.19

b.001 b.001 .87 b.001 b.001 .42 .42

A total of 138 patients received prehospital fibrinolysis. Delay in EMS response (call to on scene) was calculated from the documented date and time of the first patient call to the date and time of the mobile emergency care unit (SMUR) arrival on the scene. Time to fibrinolysis was calculated from the first patient call to needle. Time to primary PCI was calculated from the first patient call to the first balloon inflation. Median times do not sum arithmetically. Values were missing for time to fibrinolysis in 1 patient and time to PCI in 3 patients. b

EMS triage of acute myocardial infarction

4. Discussion Timely reperfusion therapy for patients with STEMI activating EMSs requires accurate identification of acute coronary syndrome by the dispatcher. In this study, 30% of EMS users with STEMI received an inappropriate initial decision despite telephone triaging by trained physicians. The main reason for this finding is probably that telephone triage of acute coronary syndrome is difficult even with the help of a computerized clinical decision support system [17-19,27]. Chest pain alone has been shown to be a poor indicator of acute coronary syndrome, and other symptoms are of limited additional value. Moreover, the symptoms of acute coronary syndrome may progress between the first and subsequent calls, explaining some of the inappropriate initial EMS dispatcher decisions. Among the potential triaging criteria investigated in our study, a history of coronary artery disease and prior PCI were both associated with a trend toward less frequent inappropriate initial dispatcher decisions, although this did not reach statistical significance. Evidence suggests that women receive less medical and invasive treatments after acute myocardial infarction compared with men [28,29]. Although the sample size of our study was too small to adequately address this issue, we found a nonsignificant trend raising the hypothesis that women are more often inappropriately dispatched. Our study shows that the rate of inappropriate initial EMS decisions was much lower when the call was placed by a health care provider (2% vs 30%). This finding, which was expected [19], should not convey the wrong message that calling a family physician first is the appropriate course of action in response to symptoms suggestive of acute coronary syndrome. Indeed, previous studies have shown that calling a physician's office increases delay in seeking treatment for patients with STEMI [9,16,30]. The use of EMSs is associated with greater and faster receipt of reperfusion therapies for patients with STEMI in routine practice [14]. The advantages of EMS utilization over self-transportation may be partially counterbalanced by delays in dispatching a mobile emergency care unit for patients receiving an inappropriate initial EMS dispatcher's decision. In our study, an inappropriate initial decision resulted in delays increasing by 42 minutes for patients receiving fibrinolysis and 63 minutes for patients undergoing primary PCI. Reassuringly, an initial inappropriate EMS dispatcher decision did not exclude patients from reperfusion therapy or incur incremental delays after the mobile emergency care unit's arrival on the scene. An inappropriate initial EMS dispatcher decision was not associated with higher in-hospital mortality despite delays in reperfusion therapy; however, our study was not powered to detect differences in clinical outcomes such as death, given its relatively small sample size. Moreover, in-hospital mortality comparison for patients who were and were not appropriately

41 dispatched would require rigorous adjustment for imbalances in baseline characteristics and clinical course between the 2 study groups. The appropriateness of the initial EMS dispatcher decision encompasses important dimensions other than undertriage of patients with STEMI. Unnecessary dispatching of mobile intensive care units has many consequences, including safety risks to the staff and the community, the limited availability of mobile units, the increase in the EMS response time for other patients, and the financial cost of providing an unnecessary service [19]. Estimating the overtriage of patients with chest pain was not within the scope of the present analysis. A previous study reported a 28% prevalence of nonorganic disorders among cardiac emergency calls dispatched by nurses who did not use formal protocols or decision rules [19]. Telephone triaging by physicians at the EMS call center probably resulted in lower overtriage rates in our study, although this cannot be formally demonstrated. The limitations of our study should be acknowledged. First, our analysis focused on patient baseline characteristics available from a prospective registry of STEMI, and dispatchers were not asked for the reasons for inappropriate initial decision. Future prospective studies are needed to investigate the reasons why physicians at EMS call centers do not dispatch a mobile emergency care unit for hospital admission for these patients. Second, we did not investigate whether dispatcher characteristics were associated with the appropriateness of the initial decision. However, all dispatchers at our EMS call center were physicians experienced in telephone triaging [24]. Third, our study was not powered to show statistically significant differences in the percentages of inappropriate decisions according to patient characteristics. Therefore, the results of our analyses should be considered to be only hypothesis generating. Fourth, our study was conducted in a university hospital– affiliated EMS call center in France, and we cannot exclude that the results would have been different in other countries or settings. In conclusion, the initial dispatcher decision was inappropriate for 30% of EMS users with STEMI and resulted in substantially increased time to reperfusion therapy in this prospective observational study. The reasons for inappropriate initial decisions are uncertain and deserve further study. The findings from this study suggest that efforts are needed to improve the accuracy of telephone triage for patients who activate EMSs in response to symptoms suggestive of acute coronary syndrome.

Acknowledgments The following investigators and institutions participated in this study: Jacques Machecourt and Stéphanie Marlière,

42 Grenoble University Hospital; Olivier Guénot, Clinique Belledonne, Saint-Martin d'Hères; Bruno Rossignol, Benjamin Faurie, and Claire Haffner, Clinique Mutualiste, Grenoble; Christophe Escallier, Voiron General Hospital; and Hervé Labourel, Marie-Hélène Schmidt, and Jean-Pierre Torres, SAMU 38. The authors are indebted to Ms Sandrine Jean and Christine Rubio for data management. Ms Linda Northrup from English Solutions (Voiron, France) provided assistance in preparing and editing the manuscript.

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