Podcast production, editing and sound design by Anton Helman. Voice editing by Raymond Cho and Sheza Qayyum
Podcast content by Salim Rezaie, Bourke Tillmann, Brit Long, Michael Gottlieb, Justin Hensley, Hans Rosenberg, Peter Johns, Justin Morgenstern, Jeannette Wolfe and Anton Helman
Written summary & blog post by Graham Mazereeuw, edited by Anton Helman
Cite this podcast as: Helman, A. Rezaie, S. Tillman, B. M. Long, B. Gottlieb, M. Hensley, J. Rosenberg, H. Johns, P. Morgenstern, J. Wolfe, J. EM Quick Hits 23 – Clinical Probability Adjusted D-dimer, ARDS Part 2, Pharyngitis Mimics, Barotrauma, Vertigo, CPR Gender-Based Differences. Emergency Medicine Cases. October, 2020. https://emergencymedicinecases.com/em-quick-hits-october-2020/. Accessed [date].
Clinical Probability Adjusted D-Dimer: The PEGeD Study
PEGeD Study – prospective study of 2,017 patients presenting to the ED with symptoms of pulmonary embolism (NEJM, 2019)
Kearon C, de Wit K, Parpia S, et al. Diagnosis of pulmonary embolism with d-dimer adjusted to clinical probability. N Engl J Med. 2019;381(22):2125-2134.
Wells PS, Anderson DR, Rodger M, et al. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer. Ann Intern Med. 2001;135(2):98-107.
Brower RG, Lanken PN, MacIntyre N, et al. Higher versus lower positive end-expiratory pressures in patients with the acute respiratory distress syndrome. N Engl J Med. 2004;351(4):327-336.
Acute Respiratory Distress Syndrome Network, Brower RG, Matthay MA, et al. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342(18):1301-1308.
National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network, Wiedemann HP, Wheeler AP, et al. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006;354(24):2564-2575.
Guérin C, Reignier J, Richard J-C, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013;368(23):2159-2168.
National Heart, Lung, and Blood Institute PETAL Clinical Trials Network, Moss M, Huang DT, et al. Early neuromuscular blockade in the acute respiratory distress syndrome. N Engl J Med. 2019;380(21):1997-2008.
Pharyngitis is usually straightforward, but there are several dangerous mimics including epiglottitis, acute retroviral syndrome, peritonsillar abscess and retropharyngeal abscess to consider in patients presenting with sore throat and fever; prior EM Quick Hits episodes have covered Ludwig’s angina, Lemierre’s syndrome, and Kawasaki’s disease
Epiglottitis occurs with inflammation of the supraglottic airway structures, most commonly due to infection
In patients with fever, sore throat and a relatively normal appearing pharynx, think epiglottitis
Stridor and tripoding are clues for impending obstruction which can occur suddenly; these are predicted difficult airways
Involve ENT and anesthesia early; intubate in the OR, with a surgical airway prepared
Nasopharyngoscopy is your imaging of choice if available, otherwise lateral neck XR (thumbprint sign) or CT if stable
Give antibiotics and steroids ASAP
Pearl: these patients often prefer to sit up/tripoding (vs. retropharyngeal abscess patients usually prefer to lie flat)
Acute retroviral syndrome occurs in the first several months of HIV infection
Patients present with pharyngitis and flu like symptoms making it difficult to distinguish from other types of pharyngitis, however one clinical clue is the presence of generalized lymphadenopathy
Think of this condition in pharyngitis patients with generalized lymphadenopathy, symptoms lasting ≥ one week or other risk factors for HIV
Peritonsillar abscess is a purulent fluid collection between the tonsillar capsule and posterior pharyngeal muscles
The diagnosis is clinical with unilateral peritonsillar swelling and deviation of the tonsils and uvula
Ultrasound may assist in the diagnosis
Drain the abscess using incision and drainage or needle aspiration (as effective as I &D), and provide antibiotics
Barotrauma exists because of Boyle’s law: P1V1 = P2V2
The higher the environmental pressure, the more air is compressed into a smaller volume
Failure to equalize pressures while diving can cause vacuum and expansion injuries
While barotrauma can occur in the sinuses, external auditory canal, middle ear and inner ear, the most life threatening barotrauma occurs with ascent barotrauma that includes pulmonary barotrauma and arterial gas embolism
Occurs with ascent without exhaling
Causes alveolar hemorrhages, pneumothorax – both simple and tension
HINTS has a greater sensitivity for stroke than MRI at less than 48 hours
If any element favours a central cause, you must consider a central cause (most commonly a stroke)
If HINTS positive, investigate with MRI after 48 hours (MRI can miss a cerebellar stroke < 48 hours), admit if needed
If persistent vertigo and difficulty walking without observed nystagmus, the risk of a central lesion (usually an ischemic stroke) should not be considered to be low
Bottom line: MRI is not sensitive enough to rule out stroke until 48 hours after the insult.
Update 2023:A systematic review and meta-analysis assessing the diagnostic accuracy of physical exam findings for central versus peripheral causes in acute vertigo found that a general neurological examination had a sensitivity of 46.8% (95% CI 32.3-61.9%), and specificity of 92.8% (95% CI 75.7-98.1%). HINTS had a sensitivity of 92.9% (95% CI 79.1-97.9%), and specificity of 83.4% (95% CI 69.6-91.7%). HINTS+ (HINTS with hearing component) had the highest sensitivity at 99% (95% CI 73.6%-100%), and specificity of 84.8% (95% CI 70.1-93.0%). Abstract
Video demonstrating the HINTS exam: https://emcrit.org/emcrit/posterior-stroke-video/
Kattah JC, Talkad AV, Wang DZ, Hsieh Y-H, Newman-Toker DE. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009;40(11):3504-3510.
Machner B, Choi JH, Trillenberg P, Heide W, Helmchen C. Risk of acute brain lesions in dizzy patients presenting to the emergency room: who needs imaging and who does not? J Neurol. Published online May 27, 2020.
Gender-based differences in CPR
Increasingly recognized that gender differences can affect cardiovascular risk
Highest 30-day mortality from a STEMI is among females younger than 55 years old
Diabetes and cigarette smoking are stronger risk factors for cardiovascular disease in females than in males
Gender now also recognized to influence resuscitation outcomes
If collapse at home, men and women have an equal chance of receiving bystander CPR
If collapse in public, men (45%) are more likely to receive CPR than women (39%)
Reasons bystanders might be reluctant to perform CPR on a woman
Potential for inadvertent intimate touching or an erroneous sexual assault charge
Women perceived as frailer than men and may be seriously injured by CPR
Less suspicious of a cardiac cause when a woman collapses
Bottom line: Sex and gender confer important disparities in health outcomes and must continue to be addressed in research and clinical training
Blewer AL, McGovern SK, Schmicker RH, et al. Gender disparities among adult recipients of bystander cardiopulmonary resuscitation in the public. Circ Cardiovasc Qual Outcomes. 2018;11(8):e004710.
Perman SM, Shelton SK, Knoepke C, et al. Public perceptions on why women receive less bystander cardiopulmonary resuscitation than men in out-of-hospital cardiac arrest. Circulation. 2019;139(8):1060-1068.
None of the authors have any conflicts of interest to declare
Dr. Anton Helman is an Emergency Physician at North York General in Toronto. He is an Assistant Professor at the University of Toronto, Division of Emergency Medicine and the Education Innovation Lead at the Schwartz-Reisman Emergency Medicine Instititute. He is the founder, editor-in-chief and host of Emergency Medicine Cases.