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Correspondence / American Journal of Emergency Medicine 32 (2014) 466–485

identified variables. After significant deliberation, this last option was adopted by the faculty. Based on the results of the first Delphi model, we decided that a workload intensity trigger system based on the number of patients and the cognitive load assigned to them would be most appropriate. We hypothesized that the cognitive load could be derived from the intrinsic complexity of patients (eg, bronchitis vs Acute Respiratory Distress Syndrome) and from whether they had been already evaluated (ie, “in the middle of the workup” vs disposition ready) [3,6]. Using those parameters, we assigned values to each patient in the ED, including incoming ambulances and those in the waiting room, depending on their stage of evaluation (seen vs not yet seen), and Emergency Severity Index acuity level. Our tracking system, known as Mayo Clinic Yes Board [7], was able to calculate this number instantaneously. The workload intensity was defined as a summation of all patients' scores (Table). We decided that the trigger would be calculated daily at 3 AM using available realtime data. The preintervention staff structure included 1 of the attending physicians leaving at 3 AM, regardless of the workload. With the new trigger, if the calculated value reached a certain predefined threshold, the attending physician scheduled to finish at 3 AM was expected to stay until 6 AM. Both attending physicians and the charge RN received a text page warning them about the staffing decision. This automated shift extension eliminated personal judgment and dynamics from the process. Following implementation, the trigger has been reached 125 times over a 22-month time span (680 days); this represents a saving of 82% (375 vs 1665) in the number of additional hours worked by attending physicians during the same period that would have been otherwise worked. Postintervention survey-based satisfaction of our staff has been extraordinarily positive. There has been a 57% increase in the perception of quality of care and the ability to match staffing with patients volumes as well as a 47% increase in efficiency and 52% in the perception of the capability of managing the cognitive load of the patients. Our nightly length of stay has decreased from 182 to 171 minutes (6%), whereas the hospital-wide rapid response team activations on patients admitted overnight have decreased by 9%. Overall, the results of the implementation of the overnight trigger are very positive. We believe that one of the key aspects of this initiative was to base the analysis of the problem and various solutions on a series of Delphi models, where all key ED stakeholders were asked to participate [4]. This novel approach to the issue of the staffing vs patient workload intensity mismatch involved the use of a metric based on both complexity and volume to plan for the expected cognitive load that may be assigned to providers caring for patients [3]. By automating the system, we minimized the inherent human factors of staffing to provide a sustainable, unbiased, and consistent staffing allocation system. The variables in the formula are easily available and simple to calculate.

Certainly, the calculation of the workload intensity can be further modified and refined, but we believe that the concept of an automatic, real-time staffing decision support tool based on work and cognitive load analysis is a promising instrument to efficiently allocate staffing resources in an ED. Daniel Cabrera, MD Department of Emergency Medicine Mayo Clinic College of Medicine Mayo Clinic, Rochester, MN, USA E-mail address: [email protected] Jeffrey L. Wiswell, MD Department of Emergency Medicine Mayo Clinic College of Medicine Mayo Clinic, Rochester, MN, USA Department of Emergency Medicine University of California Davis Davis, CA, USA Vernon D. Smith, MD Department of Emergency Medicine Mayo Clinic College of Medicine Mayo Clinic, Scottsdale, AZ, USA Andy Boggust, MD Annie T. Sadosty, MD Department of Emergency Medicine Mayo Clinic College of Medicine Mayo Clinic, Rochester, MN, USA http://dx.doi.org/10.1016/j.ajem.2013.12.051 References [1] Asplin BR, Magid DJ, Rhodes KV, Solberg LI, Lurie N, Camargo Jr CA. A conceptual model of emergency department crowding. Ann Emerg Med 2003 Aug;42(2): 173–80. [2] McCarthy ML, Zeger SL, Ding R, Aronsky D, Hoot NR, Kelen GD. The challenge of predicting demand for emergency department services. Acad Emerg Med 2008;15(4):337–46. [3] Croskerry P, Sinclair D. Emergency medicine: a practice prone to error? CJEM 2001;3(4):271–6. [4] Okoli C, Pawlowski SD. The Delphi method as a research tool: an example, design considerations and applications. Inform Manag 2004;42(1):15–29. [5] Croskerry P, Cosby KS, Schenkel SM, Wears RL. Patient safety in emergency medicine. 1st ed. Lippincott Williams & Wilkins, 2008. Chapter 37, Shiftwork, fatigue, and safety in emergency medicine; p 259–68. [6] Laxmisan A, Hakimzada F, Sayan OR, Green RA, Zhang J, Patel VL. The multitasking clinician: decision-making and cognitive demand during and after team handoffs in emergency care. Int J Med Inform 2007;76(11–12):801–11. [7] Mayo Clinic [Internet]. Rochester (MN): Mayo Clinic. Center for Innovation. Yes Board. [cited 2013 Dec 13]. From: http://www.mayo.edu/center-for-innovation/ projects/yes-board.

Wellens syndrome presented in a patient with de Winter sign electrocardiogram☆ To the Editor,

Table Work and cognitive load work index formula Index = 0.75 1.50 0.75 0.50 1.50 1.50 0.75

× (no. × (no. × (no. × (no. × (no. × (no. × (no.

of of of of of of of

patients already seen in all ED) + patients not yet seen in all ED) + Level 1 patients in all ED) + Level 2 patients in all ED) + patients in the waiting room) + patients coming by ambulance) + red light patients coming by ambulance)

We thank Samadov et al [1] for their article titled “Acute proximal left anterior descending artery occlusion with de Winter sign,” which was published in The American Journal of Emergency Medicine. The authors wrote a very excellent case report and review on a 41year-old man presented to the emergency department because of angina-like chest pain, and interestingly, the electrocardiogram (ECG)

☆ Conflict of interest statement for all authors: We do not have any financial or nonfinancial potential conflicts of interest.

Correspondence / American Journal of Emergency Medicine 32 (2014) 466–485

showed de Winter sign in Fig. 1. We would like to put emphasis on the ECG in Fig. 2B showing the Wellens syndrome. Wellens syndrome, or left anterior descending artery (LAD) coronary T-wave syndrome, is an acute coronary syndrome characterized by ECG changes of symmetric, deeply inverted T waves or biphasic T waves in the anterior leads with preserved R-wave progression and without pathologic Q waves and ST-segment elevation. Interestingly, pain is usually resolved at the time of these ECG changes and presented with this case presentation. These ECG findings are suggestive of significant LAD stenosis, and patients are at high risk for anterior wall myocardial infarction [2]. The sensitivity, specificity, and positive predictor value of T-wave inversion for significant LAD stenosis are 69%, 89%, and 86%, respectively [3]. Narat Srivali, MD Patompong Ungprasert, MD Lee C. Edmonds, MD Department of Internal Medicine, Bassett Medical Center and Columbia University College of Physicians and Surgeons Cooperstown, NY 13326, USA E-mail address: [email protected] http://dx.doi.org/10.1016/j.ajem.2013.12.054 References [1] Samadov F, Akaslan D, Cincin A, Tigen K, Sarı I. Am J Emerg Med. 2014;32(1):110. e1-3. [2] Rhinehardt J, Brady WJ, Perron AD, et al. Electrocardiographic manifestations of Wellens' syndrome. Am J Emerg Med 2002;20(7):638. [3] Haines DE, Raabe DS, Gundel WD, Wackers FJ. Anatomic and prognostic significance of new T-wave inversion in unstable angina. Am J Cardiol 1983;52 (1):14.

Electrocardiographic criteria of proximal left anterior descending artery occlusion: sign of de Winter or Wellens? To the Editor, We have read with great interest the recently published article by Samadov et al [1] entitled “Acute proximal left anterior descending artery occlusion with de Winter sign.” In that well-described case report, the authors [1] reported a 41-year-old man with an acute thrombotic occlusion of proximal left anterior descending artery (LAD). The authors mentioned that an acute occlusion of coronary arteries could be recognized by ST-segment elevation myocardial infarction equivalents in patients presenting with an atypical electrocardiographic (ECG) manifestation. While this current case report is interesting and provides us exhaustive information, some comments may be of interesting. Precordial ST-segment depression could be regarded as an indicator of concomitant posterior involvement with high specificity (92%) [2]. In acute coronary syndrome patients presenting with precordial ST-segment depression, posterior ECG should be evaluated to detect posterior segment involment or posterior myocardial infarction, thereby avoiding timely intervention [2]. Wellens’ syndrome is characterized by specific T waves (deeply inverted or biphasic) found in precordial leads, thereby suggesting high-grade luminal narrowing of the proximal LAD [3-5]. Wellens’ sign is a predictor of acute anterior wall myocardial infarction within 1 week with high sensitivity and specificity [3,4]. As in this case, ST-segment depression with upright T waves during episodes of pain, biphasic T waves during pain-free periods, no pathologic precordial Q waves, no loss of precordial R waves, absence of ST-segment elevation in lead aVR, dynamic ECG changes, and mildly elevated cardiac enzymes could suggest us Wellens’ syndrome,

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thereby wandering away from the sign of de Winter, which represents acute proximal LAD occlusion [6]. Nonetheless, whatever the sign is, patients should undergo urgent cardiac catheterization in both conditions. Emre Yalcinkaya, MD Department of Cardiology, Aksaz Military Hospital 48750, Mugla, Turkey E-mail address: [email protected] Murat Celik, MD Department of Cardiology, Gulhane Military Medical Faculty 06018, Ankara, Turkey http://dx.doi.org/10.1016/j.ajem.2013.12.057 References [1] Samadov F, Akaslan D, Cincin A, Tigen K, Sarı I. Acute proximal left anterior descending artery occlusion with de Winter sign. Am J Emerg Med 2014;32(1):110. e1-3. [2] Sugiura T, Iwasaka T, Takehana K, Nagahama Y, Hasegawa T, Inada M. Precordial ST segment depression in patients with Q wave inferior myocardial infarction: role of infarction-associated pericarditis. Am Heart J 1993;125(3):672–5. [3] Ahmed S, Ratanapo S, Srivali N, Ungprasert P, Cheungpasitporn W, Chongnarungsin D. Wellens’ syndrome and clinical significance of T-wave inversion in anterior precordial leads. Am J Emerg Med 2013;31(2):439–40. [4] Mead NE, O'Keefe KP. Wellens’ syndrome: an ominous EKG pattern. J Emerg Trauma Shock 2009;2(3):206–8. [5] Parikh KS, Agarwal R, Mehrotra AK, Swamy RS. Wellens’ syndrome: a life-saving diagnosis. Am J Emerg Med 2012;30(1):255.e3-5. [6] de Winter RJ, Verouden NJW, Wellens HJJ, Wilde AAM. A new ECG sign of proximal LAD occlusion. N Engl J Med 2008;359:2071–3.

Determining the etiology of hypotension: associated with reperfusion injury?☆ To the Editor, We read the recently published article by Zarar et al [1] entitled “Anaphylactic shock associated with intravenous thrombolytics” with great interest. In that well-described case report, the authors [1] presented a case of an anaphylactic reaction directly attributable to intravenous recombinant tissue plasminogen activator (r-tPA). Although we commend the authors for their valuable article, some comments may be beneficial. Type I hypersensitivity is an allergic reaction provoked by reexposure to a specific antigen [2]. Anaphylactic shock, a systemic form of type I hypersensitivity, is associated with systemic vasodilation that could cause low blood pressure. Given that the late-phase type 1 hypersensitivity reaction could occur 1 to 4 hours after the exposure to an antigen [2,3], omnipaque iodinated contrast agent could not be excluded to be a potential antigen. Ischemia-reperfusion–induced cerebral or cardiac injury could result in systemic hypotension. Reperfusion-induced cerebral injury could result in hypotension due to cerebral reactive hyperemia as a consequence of repressurization in hypotensive vascularity [4]. Reflex hypotension and bradycardia could be observed after cardiac reperfusion therapy associated with the Bezold-Jarisch reflex, which maintains the arterial pressure constant [5,6]. Consequently, hypersensitivity to recombinant tissue plasminogen activator or omnipaque iodinated contrast agent could have been determined before administration. The lack of accompanying symptoms of anaphylactic reaction causes us to question the diagnosis of anaphylactic shock. Hypotension could be associated with either anaphylactic reaction or reperfusion-induced cerebral injury. ☆ Conflict of interest: None declared.

Wellens syndrome presented in a patient with de Winter sign electrocardiogram.

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