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[7] Mittadodla PS, Kumar S, Smith E, Badireddy M, Turki M, Fioravanti GT. CT pulmonary angiography: an over-utilized imaging modality in hospitalized patients with suspected pulmonary embolism. J Community Hosp Intern Med Perspect 2013;3(1). [8] Perrier A, Roy PM, Aujesky D, Chagnon I, Howarth N, Gourdier AL, et al. Diagnosing pulmonary embolism in outpatients with clinical assessment, D-dimer measurement, venous ultrasound, and helical computed tomography: a multicenter management study. Am J Med 2004;116:291–9. [9] Righini M, Le Gal G, Aujesky D, Roy PM, Sanchez O, Verschuren F, Richman PB, Courtney DM. Diagnosis of pulmonary embolism by multidetector CT alone or combined with venous ultrasonography of the leg: a randomised non-inferiority trial. Lancet 2008;371:1343–52. [10] Kline JA, Mitchell AM, Kabrhel C, et al. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism. J Thromb Haemost 2004;2:1247–55. [11] Roy PM, Colombet I, Durieux P, Chatellier G, Sors H, Meyer G. Systematic review and meta-analysis of strategies for the diagnosis of suspected pulmonary embolism. BMJ 2005;33:259. [12] Jiang LB, Ma YF, Zhang M. Can mean platelet volume predict the prognosis of patients with acute kidney injury requiring continuous renal replacement therapy? J Crit Care 2015;30:207. [13] Varol E. Mean platelet volume in supraventricular tachyarrhythmia can be affected by many cardiovascular risk factors. Afr Health Sci 2013;13:1176–7. [14] Yuksel O, Helvaci K, Basar O, Köklü S, Caner S, Helvaci N, et al. An overlooked indicator of disease activity in ulcerative colitis: mean platelet volume. Platelets 2009;20: 277–81. [15] Kisacik B, Tufan A, Kalyoncu U, Karadag O, Akdogan A, Ozturk MA, et al. Mean platelet volume (MPV) as an inflammatory marker in ankylosing spondylitis and rheumatoid arthritis. Joint Bone Spine 2008;75:291–4. [16] Danese S, Motte Cd Cde L, Fiocchi C. Platelets in inflammatory bowel disease: clinical, pathogenic, and therapeutic implications. Am J Gastroenterol 2004;99:938–45. [17] Tanrikulu CS, Tanrikulu Y, Sabuncuoglu MZ, Karamercan MA, Akkapulu N, Coskun F. Mean platelet volume and red cell distribution width as a diagnostic marker in acute appendicitis. Iran Red Crescent Med J 2014;16:e10211. [18] Erikci AA, Karagoz B, Ozturk A, Caglayan S, Ozisik G, Kaygusuz I, et al. The effect of subclinical hypothyroidism on platelet parameters. Hematology 2009;14:115–7.

Diagnostic Value of Platelet Indices for Pulmonary Embolism: The authors respond To the Editor, First, we really appreciate to get the author's interest about our article [1]. We have read very carefully the letter and the references given by the author. We are honored to discuss the questions mentioned. 1. The spectrum of patients must be representative of the patients who will receive the test in practice [2]. We agree with this view. Our study was a retrospectively casecontrol study. All the patients in our study were suspected pulmonary embolism (PE), and corresponding examinations were carried out including blood sample examination and computed tomography pulmonary angiography (CTPA). Pulmonary embolism was confirmed by CTPA [3]. The patients with “positive” CTPA results were included in the case group, and the patients with “negative” CTPA results were included in the control group. Thank the author to help us find that it is not rigorous in the text representation. It should be better to add “suspected PE” as an attributive of the patients admitted to our hospital. 2. The prevalence of PE in our study is too high. Firstly, our study was not a cross-sectional study, thus the proportion of PE could not represent the prevalence of PE in the general population. Secondly, the sample size was small. In fact, when we retrospectively searched in our image workstation system, we found that the number of the patients who confirmed PE after CTPA was not more than one-fourth of all those who performed CTPA. It was not our aim to evaluate the prevalence of PE, so we only chose the patients matched to our inclusion criteria and matched age and sex between the 2 groups. 3. Does the posttest probability of PE change after the performance of platelet indexes? We agree that it is more comprehensive to evaluate the value of mean platelet volume (MPV), if the changed posttest probability of

PE after the performance of MPV has been evaluated. To compare the posttest probability of PE among different diagnostic tests, the study should be prospective [4] with a large enough sample size, and the suspected patients should be strictly grouped according to different diagnostic strategies. Our study did not meet these requirements. We look forward to evaluate this index in the future studies. 4. The value of MPV is affected by many factors. We had realized that it might be more accurate to evaluate the diagnostic value of MPV after excluding the influencing factors. But it was difficult to rule out all these factors. As a retrospective study, the medical history of the patients might be incomplete, and relevant examinations might be inadequate. For example, it is not routine to carry out examinations associated with rheumatic and immune diseases. In addition, the value of MPV is significantly variable because of technical reasons [5]. The clinical application of MPV alone is limited. Thank the author again. It is pleasant to discuss medical problems with others. Jianqiang Huang, MD⁎ Yanyan Chen, BSN Zhixiong Cai, MD Ping Chen, MD Department of Cardiovascular Medicine Shantou Central Hospital, Guangdong, China ⁎Corresponding author. Department of Cardiovascular Medicine Shantou Central Hospital, No. 114, Waima Road, Shantou City Guangdong Province, China. Tel./fax: +86 0754 88550450 E-mail address: [email protected]

http://dx.doi.org/10.1016/j.ajem.2015.04.013 References [1] Jianqiang H, Yanyan C, Zhixiong C, Ping C. Diagnostic value of platelet indexes for pulmonary embolism. Am J Emerg Med 2015 [Epub ahead of print]. [2] Whiting Penny, Rutjes Anne WS, Reitsma Johannes B, Bossuyt Patrick MM, Kleijnen Jos. The development of QUADAS: a tool for the quality assessment of studies of diagnostic accuracy included in systematic reviews. BMC Med Res Methodol 2003;3:25–37. [3] Torbieki A, Perrier A, Konstantinides S, Agnelli G, Galiè N, Pruszczyk P, et al. ESC Committee for Practice Guide1ines (CPG). Guidelines on the diagnosis and management of acute pulmonary embolism: the Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC). Eur Heart J 2008;29:2276–315. [4] Roy PM, Colombet I, Durieux P, Chatellier G, Sors H, Meyer G. Systematic review and meta-analysis of strategies for the diagnosis of suspected pulmonary embolism. BMJ 2005;33:259–67. [5] Leader A, Pereg D, Lishner M. Are platelet volume indices of clinical use? A multidisciplinary review. Ann Med 2012;44(8):805–16.

Dengue myocarditis and profound shock

To the Editor, The report on “dengue myocarditis and profound shock” by Lin et al [1] is very interesting. Dengue infection can be severe and result in shock. Indeed, clinically, shock is possible in any dengue case, whereas the systemic complications of dengue myocarditis are not related to shock [2]. In the present case [1], it might be only concomitant. Focusing on myocarditis, it is a rare clinical manifestation of dengue [3]. It is usually not a fatal problem [3]. The fatality in the present case [1] could be directly related to dengue shock, not myocarditis. In the present case, the poor fluid replacement therapy might be the cause of profound shock and fatality. In addition, there might be a possible underlying cardiac problem that might induce a more serious cardiac pathology when myocarditis occurs.

Correspondence / American Journal of Emergency Medicine 33 (2015) 1093–1107

Somsri Wiwanitkit, PhD Wiwanitkit House, Bangkhae, Bangkok, Thailand Corresponding author at: Wiwanitkit House, Bangkhae Bangkok, Thailand 10160 E-mail address: [email protected] Viroj Wiwanitkit, MD Hainan Medical University, Haikou, Hainan, China Faculty of Medicine, University of Nis, Nis, Serbia Joseph Ayobabalola University, Nigeria Dr DY Patil Medical University, Pimpri, Pune, Maharashtra, India

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Subramanian Senthilkumaran, MD, Dip A&E, FCCM Department of Emergency and Critical Care Sri Gokulam Hospitals, Salem, Tamil Nadu, India Corresponding author. Department of Emergency & Critical Care Medicine, Sri Gokulam Hospital, Salem 636004, Tamil Nadu, India Tel.: +91 999 4634 444 (mobile) E-mail address: [email protected] Shah Sweni, MD Department of Emergency and Critical Care Sri Gokulam Hospitals, Salem, Tamil Nadu, India Department of Internal Medicine, Chennai Medical College Hospital and Research Center, Irungalur, Trichy, Tamil Nadu, India

http://dx.doi.org/10.1016/j.ajem.2015.04.059 Namasivayam Balamurugan, MD, DM Department of Neurosciences SIMS Chellam Hospital, Salem, Tamil Nadu, India

References [1] Lin TC, Lee HC, Lee WH, Su HM, Lin TH, Hsu PC. Fulminant dengue myocarditis complicated with profound shock and fatal outcome under intra-aortic balloon pumping support. Am J Emerg Med 2015. http://dx.doi.org/10.1016/j.ajem.2015.03.039 [pii: S0735-6757(15)00183-7, Epub ahead of print]. [2] Wiwanitkit V. Acute shock dengue myocarditis. Rev Esp Cardiol 2014;67(6):502. [3] Wiwanitkit V. Dengue myocarditis, rare but not fatal manifestation. Int J Cardiol 2006; 112(1):122.

Narendra Nath Jena, FAEM Department of Emergency Medicine Meenakshi Mission Hospital and Research Centre Madurai, Tamil Nadu, India Ponniah Thirumalaikolundusubramanian, MD Department of Internal Medicine, Chennai Medical College Hospital and Research Center, Irungalur, Trichy, Tamil Nadu, India http://dx.doi.org/10.1016/j.ajem.2015.04.072

Hounsfield units in pseudosubarachnoid hemorrhage—an old yet fascinating tool☆,☆☆

To the Editor, The importance of recognizing pseudosubarachnoid hemorrhage (PSAH) in a case of dialysis disequilibrium syndrome was “illustrated” by Tsai et al [1]. However, the appearance of PSAH within the basal cisterns, in conjunction with diffuse cerebral edema, has received limited attention in medical literature. We would like to stress the usefulness of Hounsfield units (HU) to distinguish PSAH from SAH with reference to the report published [1]. Literature suggests autopsy and cerebrospinal fluid studies are the ways to confirm PSAH. In contrast, careful measurement of the density of different visible elements in cranial computed tomography scans by HU [2] helps discriminate hyperintensity of SAH from PSAH even in antemortem. Many recent computed tomography software programs have the capability to appraise even tiny areas precisely and assist to differentiate normal from edematous parenchyma or hemorrhage. The HU of SAH is between 60 and 70, which is higher than both normal gray matter (30-40 HU) and white matter (20-30 HU), whereas the HU of PSAH varies from 29 to 33 [3]. With lower HU, values are presumed to indicate PSAH and obviate more invasive testing [4]. Awareness of the various manifestations of PSAH is important for patient counseling and management because treatment is different and could potentially change outcomes. One should assess the abnormalities detected in computed tomography by HU before making decisions or pronouncing statements. Failure to differentiate SAH from PSAH may result in peril of patient safety. Hence, all emergency physicians should be familiar with these potential mimics of SAH. In fact, HU should be included in regular practice and for discussion in clinical rounds.

☆ Financial support: Nil. ☆☆ Conflict of interest: Nil.

References [1] Tsai WC, Chen JC, Tsao YT. Pseudosubarachnoid hemorrhage: an ominous sign in dialysis disequilibrium syndrome. Am J Emerg Med 2015;33(4):602.e3–4. [2] Avrahami E, Katz R, Rabin A, Friedman V. CT diagnosis of non- traumatic subarachnoid haemorrhage in patients with brain edema. Eur J Radiol 1998;28:222–5. [3] Given CA, Burdette JH, Elster AD, Williams DW. Pseudo- subarachnoid hemorrhage: a potential imaging pitfall associated with diffuse cerebral edema. AJNR Am J Neuroradiol 2003;24:254–6. [4] Senthilkumaran S, Balamurugan N, Menezes RG, Thirumalaikolundusubramanian P. Role of Hounsfield units to distinguish pseudo-subarachnoid hemorrhage. Clin Toxicol (Phila) 2011;49:948.

Lung Ultrasound for Chest Tube Insertion

To the Editor, We read with interest the observational study by Matsumoto et al [1] identifying the incidence and corresponding risk factors for traumatic pneumothoraxes in the presence of a hemothorax, which should be monitored. This secondary end point was designed to identify the incidence of malpositioned chest tubes based on different insertion directions using computed tomography (CT). The analysis of 78 chest tubes insertions revealed that posterior insertion for monitoring of hemothoraces is more often useless than anterior position. Among the 42 chest tubes with a posterior insertion, 20 (48%) were radiologically malpositioned vs 4 (13%) of the chest tubes among the 32 patients with an anterior insertion. The rates of both radiologic and functional malpositioning with a posterior chest tube insertion were significantly higher than in patients with an anterior insertion (P b .01). The malposition of chest tubes is responsible for an increased rate of nonfunctional chest tubes and an increased mortality [2]. In the discussion section, Matsumoto et al propose that malpositioning can be identified using portable chest radiography in trauma care after the insertion is completed. They also highlight the higher malposition rate identified with the use of CT. We would like to go further into the discussion and propose that lung ultrasounds (US) help the clinicians in beside