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Correspondence
The authors' response to comments
College of Medicine Yonsei University Seoul, Korea
To the Editor, We would like to thank Dr Xue for his interest and insightful comments on our recent report [1]. We certainly agree with his 2 points that the participants in our study should not be regarded as novices to 2 video laryngoscopes (VLs) and that Macintosh laryngoscope (MAC) is generally more cost-effective than the VLs. However, in the aspect of clinical experiences, the participants' experiences in the VLs are different from the MAC. Like direct laryngoscopic intubation, clinical experiences in addition to training on manikin are required for adequate skill acquisition of indirect laryngoscopic intubation using new VLs. Although they received prior training with the VLs in a manikin with normal airway, the clinical experiences could influence their performance in a simulated cardiac arrest situation. Rescuers must be aware of risks and benefits of insertion of an advanced airway during a resuscitation attempt. Such risks are affected by the condition of the patient and the rescuer's expertise in airway management. Direct laryngoscopic intubation using the MAC has been widely used for advanced airway management during cardiopulmonary resuscitation (CPR). Although the direct laryngoscopic intubation has many benefits, skill acquisition is not easy and requires a long learning time [2-4]. If there is a device that has a rapid learning curve and not affected by chest compressions, it might be a useful adjunct or alternative tool in advanced airway management during CPR. Although the evidence was not robust, both the VLs have been used successfully in patients with anticipated difficult airways and difficult clinical conditions [5-8]. Therefore, considering situational urgency of cardiac arrest, risks of failed intubation due to unexpected difficult airway during emergency intubation, and relatively shorter learning time, the VLs may be useful adjuncts or backup tools for experienced intubators during CPR. Young-Min Kim MD Ji-Hoon Kim MD Department of Emergency Medicine College of Medicine The Catholic University of Korea Seoul, Korea E-mail address:
[email protected] Hyung-Goo Kang MD Department of Emergency Medicine College of Medicine Hanyang University Seoul, Korea Hyun Soo Chung MD Department of Emergency Medicine
Hyeon-Woo Yim MD, MPH Department of Preventive Medicine College of Medicine The Catholic University of Korea Seoul, Korea CMC Clinical Research Coordinating Center The Catholic University of Korea Seoul, Korea Seung-Hee Jeong MPH CMC Clinical Research Coordinating Center The Catholic University of Korea Seoul, Korea doi:10.1016/j.ajem.2010.09.024
References [1] Kim YM, Kim JH, Kang HG, et al. Tracheal intubation using Macintosh and 2 video laryngoscopes with and without chest compressions. Am J Emerg Med 2010;28. doi:10.1016/j.ajem. 2010.02.014. [2] Konrad C, Schüpfer G, Wietlisbach M, et al. Learning manual skills in anesthesiology: is there a recommended number of cases for anesthetic procedures? Anesth Analg 1998;86:635-9. [3] Mulcaster JT, Mills J, Hung OR, et al. Laryngoscopic intubation: learning and performance. Anesthesiology 2003;98:23-7. [4] Wang HE, Seitz SR, Hostler D, et al. Defining the “learning curve” for paramedic student endotracheal intubation. Prehosp Emerg Care 2005; 9:156-62. [5] Cooper RM, Pacey JA, Bishop MJ, McCluskey SA. Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients. Can J Anesth 2005;52:191-8. [6] Choi HJ, Kang H-G, Lim TH, et al. Endotracheal intubation using a GlideScope video laryngoscope by emergency physicians: a multicentre analysis of 345 attempts in adult patients. Emerg Med J 2010; 27:380-2. [7] Asai T, Liu EH, Matsumoto S, et al. Use of the Pentax-AWS® in 293 patients with difficult airways. Anesthesiology 2009;110: 898-904. [8] Komatsu R, Kamata K, Daniel I, Sessler DI, et al. Airway Scope and Macintosh laryngoscope for tracheal intubation in patients lying on the ground. Anesth Analg 2010;111:427-31.
Temporal pattern of occurrence of cardiac emergencies To the Editor, We have read with interest the article by Li et al [1] dealing with temporal distribution of onset of acute coronary syndrome (ACS). However, although we appreciate the quality of the study and the efforts of the authors, we do not agree with some statements, and at least a series of considerations are to be made.
Correspondence
1. In-hospital vs out-of-hospital patients In their introduction and discussion, the authors affirm that previous studies on circadian rhythm of ACS were based on in-hospital series, no study has examined the presentation of ACS in the prehospital setting, and this represents the first study examining the circadian rhythm of ACS cases derived from the prehospital data. Unfortunately, these are not correct. Most studies of the last 2 decades (including the milestone ones) [2-4] dealt with case series of patients experiencing their ACS—in particular, acute myocardial infarction (AMI), sudden death, and cardiac arrest—out-of-hospital and only successively assisted by an emergency rescue team or directly referred to the hospital. In fact, also under a methodological point of view, it is extremely unusual that studies on chronobiologic variations may be performed on in-hospital patients, and this has to be clearly stated [5]. This is because hospitalization and hospital-driven rhythms may alter or mask endogenous rhythms. Thus, the optimal for methodologically correct studies is to address out-of-hospital subjects. Moreover, at least 1 article, published in this Journal, has been addressed to out-of-hospital emergencies [6]. The study, conducted on more than 20 000 emergency calls to the Italian telephone number 118 (the equivalent of 911 in the United States) confirmed a morning pattern for those (more than 3000) with attribution of a “cardiologic” code. The conclusion of this article was that it is possible to suggest a morning-load staffing pattern also for ambulance service. In fact, this morning load was reported also by previous studies that found a clear circadian variation in the distribution of requests for helicopter transport of cardiac patients [7].
2. Biphasic pattern of ACS The existence of a biphasic pattern (morning-evening) is well known, both for AMI [8-10], ischemic and hemorrhagic stroke [11,12], and rupture/dissection of aortic aneurysms [13,14]. At least for stroke, the mechanisms underlying the double peak have been described: secondary peak of blood pressure, afternoon catecholamine increase, waking up from an afternoon siesta (that exposes to the same risk of waking up in the morning) are plausible explanations [15]. Moreover, type and severity of ACS may also vary by time of day. For example, a significant and important variability in the type of ACS (ST-elevation myocardial infarction [STEMI], non–STEMI, and unstable angina) based on the time of day of presentation has been reported [16]. In the absence of meaningful differences in sex or age between groups, only 35.8% of patients for whom time of presentation was available (n = 1869) presented during the 12 hours defined as night (P b .001). Although this reduced frequency of ACS admissions at nighttime, a significant difference was found in the overall distribution of all 3 types of ACS. In fact, the proportion presenting with STEMI was 30.9% higher at nighttime
129 compared with daytime (P = .022), with corresponding significant decreases in unstable angina at nighttime. As a result of the increased STEMI, the proportion of ACS presenting with AMI increased 7.1% at nighttime (P = .033).
3. Weekly distribution The Monday peak of MI (quite similar to that of ischemic stroke) [17] has been widely investigated, and a metaanalysis on 21 available studies, aimed to quantify the excess risk associated with the Monday peak in cardiovascular mortality, found an increased pooled odds ratio of 1.19, without significant differences between subgroups by sex and age [18]. Another confirmation study of the Monday peak of AMI, conducted in the database of the EmiliaRomagna region of Italy (accounting for more than 64 000 infarctions), has been recently published in this Journal [19]. Moreover, it is not true that Willich et al [20] “indicated no significant weekly variation at all.” The authors simply found that this weekly variation with a Monday peak was present only in the working but not in nonworking population. Of course, it is true that some studies did not find a weekly variation, as also Lit et al did [1]. In our opinion, under the research point of view, negative results are equally important with positive results. However, when the term “first” is used, a complete study of the available literature is mandatory. THE AUTHOR RESPONDS (1) It is not uncommon that some authors have different understanding of the reference articles mentioned. (2) Some studies have different results on a particular topic. Simply comparing the results of one or several previous studies without a complete meta-analysis is not particularly convincing. (3) In previous studies, different ethnic populations with different cultures were studied. The lifestyles are not similar, and lifestyle is definitely related to people's health. In our article, the reasons for the temporal pattern of our people were discussed, and the difference of the previous researches was analyzed. This seems to have been overlooked by the reader. (4) Through a communication, we would have hoped that the reader would also provide new ideas or publish their new data. Unfortunately, these do not appear in their correspondence. Houli Wang, MD
Roberto Manfredini MD Department of Internal Medicine Hospital of the Delta Azienda USL di Ferrara, Italy Department of Clinical and Experimental Medicine Section of Clinica Medica and Vascular Diseases Center University of Ferrara, Italy E-mail address:
[email protected]
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Correspondence Massimo Gallerani MD Department of Internal Medicine Hospital of Ferrara, Italy
doi:10.1016/j.ajem.2010.09.028
References [1] Li Y, Du T, Lewin MR, et al. Circadian, day-of-week, and age patterns of the occurrence of acute coronary syndrome in Beijing's emergency medical services system. Am J Emerg Med 2010;28:663-7. [2] Muller JE, Ludmer PL, Willich SN, et al. Circadian variation in the frequency of onset of sudden cardiac death. Circulation 1987;75:131-8. [3] Muller JE, Stone PH, Turi ZG, et al. Circadian variation in the frequency of onset of acute myocardial infarction. N Engl J Med 1985; 313:1315-22. [4] Levine RL, Pepe PE, Fromm RE, et al. Prospective evidence of a circadian rhythm for out-of-hospital cardiac arrests. JAMA 1992;267: 2935-7. [5] Manfredini R, Gallerani M, Salmi R, Zamboni P, Fersini C. Fatal pulmonary embolism in hospitalized subjects: evidence for a winter peak. J Int Med Res 1994;22:85-9. [6] Manfredini R, la Cecilia O, Boari B, et al. Circadian pattern of emergency calls: implications for ED organization. Am J Emerg Med 2002;20:282-6. [7] Fromm RE, Levine RL, Pepe PE. Circadian variation in the time of request for helicopter transport of cardiac patients. Ann Emerg Med 1990;21:1196-9. [8] Behar S, Halabi M, Reicher-Reiss H, et al. Circadian variation and possible external triggers of onset of myocardial infarction. SPRINT Study Group. Am J Med 1993;94:395-400.
[9] Peters RW, Zoble RG, Liebson PR, Pawitan Y, Brooks MM, Proschan M. Identification of a secondary peak in myocardial infarction onset 11 to 12 hours after awakening: the Cardiac Arrhythmia Suppression Trial (CAST) experience. J Am Coll Cardiol 1993;22:998-1003. [10] Manfredini R, Boari B, Bressan S, et al. Influence of circadian rhythm on mortality after myocardial infarction: data from a prospective cohort of emergency calls. Am J Emerg Med 2004;22:555-9. [11] Casetta I, Granieri E, Fallica E, la Cecilia O, Paolino E, Manfredini R. Patient demographic and clinical features and circadian variation in onset of ischemic stroke. Arch Neurol 2002;59:48-53. [12] Casetta I, Granieri E, Portaluppi F, Manfredini R. Circadian variability in hemorrhagic stroke. JAMA 2002;287:1266-7. [13] Manfredini R, Portaluppi F, Zamboni P, Salmi R, Gallerani M. Circadian variation in spontaneous rupture of abdominal aorta. Lancet 1999;353:643-4. [14] Mehta HR, Manfredini R, Hassan F, et al. Chronobiological patterns of acute aortic dissection. Circulation 2002;106:1110-5. [15] Manfredini R, Boari B, Smolensky MH, et al. Circadian variation in stroke onset: identical temporal pattern in ischemic and hemorrhagic events. Chronobiol Int 2005;22:417-53. [16] LaBounty T, Eagle KA, Manfredini R, et al. The impact of time and day on the presentation of acute coronary syndromes. Clin Cardiol 2006;29:542-6. [17] Manfredini R, Casetta I, Paolino E, et al. Monday preference in onset of ischemic stroke. Am J Med 2001;111:401-3. [18] Witte DR, Grobbee DE, Bots ML, Hoes AW. Meta-analysis of excess cardiac mortality on Monday. Eur J Epidemiol 2005;20:401-6. [19] Manfredini R, Manfredini F, Boari B, et al. Seasonal and weekly patterns of hospital admissions for nonfatal and fatal myocardial infarction. Am J Emerg Med 2009;27:1096-102. [20] Willich SN, Lowel H, Lewis M, Hormann A, Arntz HR, Keil U. Weekly variation of acute myocardial infarction: increased Monday risk in the working population. Circulation 1994;90:87-93.
