Topics in this EM Quick Hits podcast
Emily Austin on physostigmine for anticholinergic toxidrome (1:02)
Walter Himmel on understanding nystagmus to differentiate central vs peripheral causes of vertigo (07:00)
Rob Devins on the role of transesophageal echocardiogram in cardiac arrest (18:43)
Jesse MacLaren on nuances in inferior MI ECG changes and aVL (25:06)
Andrew Petrosoniak on a practical approach to blunt cerebrovascular injury (29:43)
Reuben Strayer on choicebo (38:46)
Podcast production, editing and sound design by Anton Helman
Podcast content, written summary & blog post by Andrew Petrosoniak, Emily Austin, Sucheta Sinha and Anton Helman
Cite this podcast as: Helman, A. Petrosoniak, A. Austin, E. Devin, R. Himmel, W. Strayer, R. EM Quick Hits 11 – Blunt Cerebrovascular Injury, Physostigmine, TEE in Cardiac Arrest, Understanding Nystagmus, Subtle Inferior MI, Choicebo. Emergency Medicine Cases. December, 2019. https://emergencymedicinecases.com/em-quick-hits-december-2019/. Accessed [date].
The return of physostigmine for antimuscarinic poisoning delirium
- Recall anticholinergic/antimuscarinic poisoning toxidrome: “mad as a hatter, blind as a bat, red as a beet, dry as a bone, hot as hell, full as a flask” – hyperthermic, hypertensive, tachycardic, dry axilla (compared to sympathomimetic patients who will often be diaphoretic), agitated, delirious, urinary retention, pupillary dilation.
- Benzodiazepines are often used to control agitation, but they are sedating and will not resolve the delirium associated with the antimuscarinic toxidrome.
- Physostigmine, the antidote for the antimuscarinic toxidrome reverses both agitation and delirium.
- Physostigmine has suffered from a bad reputation after being incorrectly used in TCA overdose with QRS prolongation, leading to cardiac arrest in case reports.
- It is safe and effective in anticholinergic overdose associated with delirium as long as the ECG shows a normal QRS and QTc.
- Physostigmine dose is 1-2 mg IV over 10 minutes for adults and 0.02 mg/kg for children. It may need to be re-dosed if symptoms return.
- Arens AM, Shah K, Al-abri S, Olson KR, Kearney T. Safety and effectiveness of physostigmine: a 10-year retrospective review<sup></sup>. Clin Toxicol (Phila). 2018;56(2):101-107.
- Burns MJ, Linden CH, Graudins A, Brown RM, Fletcher KE. A comparison of physostigmine and benzodiazepines for the treatment of anticholinergic poisoning. Ann Emerg Med. 2000;35(4):374-81.
Understanding nystagmus to differentiate central vs peripheral causes of vertigo
- Differentiating the various types of nystagmus can help differentiate central vs peripheral causes of vertigo.
- Two main types of nystagmus: pendular nystagmus (eyes move repetitively in a sinusoidal pattern) and jerk nystagmus (eyes move slowly in one direction and rapidly correct in the opposite direction).
- Types of jerk nystagmus that are always central: pure vertical, pure rotational, and multidirectional nystagmus (where the fast component changes direction depending on which direction the patient is looking).
- Types of jerk nystagmus that are almost always peripheral: unidirectional horizontal nystagmus (fast component is in the same direction regardless of where the patient is looking), vertical rotational nystagmus (the most common nystagmus seen in BPPV).
- Serra A, Leigh RJ. Diagnostic value of nystagmus: spontaneous and induced ocular oscillations. J Neurol Neurosurg Psychiatry. 2002;73(6):615-8.
- Kupersmith MJ. Practical classification of nystagmus in the clinic. Arch Ophthalmol. 2008;126(6):871-2.
TEE in cardiac arrest: Is there a role?
- During and post cardiac arrest, transesophageal echo (TEE) may have a role in improving chest compressions quality, shorten pulse check times, guiding differential diagnosis and allowing adequate cardiac views in a small subset of patients where no window exists subxiphoid or transthoracically
- However, there is no patient-oriented outcome data to date.
- Compared to transthoracic/subxyphoid POCUS, TEE often generates better quality images and does not take up important space on the patient’s chest needed for compressions, defibrillator pads etc.
- TEE requires a dedicated physician during cardiac arrest.
- There exist descriptions of effective simulator-based training strategies as well as workshops for TEE skill learning
- Chenkin J, Hockmann E, Jelic T. Simulator-based training for learning resuscitative transesophageal echocardiography. CJEM. 2019;21(4):523-526.
- Parker BK, Salerno A, Euerle BD. The Use of Transesophageal Echocardiography During Cardiac Arrest Resuscitation: A Literature Review. J Ultrasound Med. 2019;38(5):1141-1151.
- Fair J, Mallin M, Mallemat H, et al. Transesophageal Echocardiography: Guidelines for Point-of-Care Applications in Cardiac Arrest Resuscitation. Ann Emerg Med. 2018;71(2):201-207.
The wonders of aVL in detecting inferior STEMI early
- aVL is reciprocal to the inferior wall
- ST changes in aVL may precede ST changes of inferior STEMI thus allowing for early diagnosis, heightened scrutiny in serial ECG interpretation for an evolving inferior STEMI, and earlier time to definitive treatment
- In a 1993 study of 107 patients with inferior MI, only 61% of patients had 1mm of ST elevation in all three leads, and this only rose to 87% if the threshold was dropped to 1mm of ST elevation in one inferior lead (13% of inferior MI had no significant ST elevation in any lead), however, 0.5mm ST depression in aVL was 97% sensitive for identifying inferior MI.
- ST changes in aVL may also help differentiate MI from pericarditis
For further details and to improve your skills in using aVL in STEMI run through the 8 cases on ECG Cases #3
- Birnbaum Y, Sclarovsky S, Mager A, Strasberg B, Rechavia E. ST segment depression in a VL: a sensitive marker for acute inferior myocardial infarction. Eur Heart J. 1993;14(1):4-7.
- Marti D, Mestre JL, Salida L, et al. Incidence, angiographic features and outcomes of patients presenting with subtle ST-elevation myocardial infarction. Am Heart J 2014;168(6): 884-890
- Bischof J, Worral C, Thompson P, et al. ST depression in lead aVL differentiates inferior ST elevation myocardial infarction from pericarditis”. Am J Emerg Med. 2015;34(2):149-154.
Practical approach to blunt cerebrovascular injury
- Think about the possibility of blunt cerebrovascular injury in your head injured patients getting a CT head and/or neck, an often under-recognized phenomenon.
- Non penetrating injury to the carotid or vertebral arteries in trauma can result in aneurysm, dissection (with subsequent ischemic stroke), and even transection.
- The Denver Criteria have 97% sensitivity and 47% specificity for blunt cerebrovascular injury.
- If positive by the Denver criteria, CTA of the head and neck is the imaging modality of choice in the ED.
- Decision making in blunt cerebrovascular injury treatment involves weighing the risk of bleeding (in the trauma patient who may have other injuries) with anti-thrombotic medications, against the risk of stroke without these medications; consultation with neurosurgery/neurology is advised.
- Grigorian A, Kabutey NK, Schubl S, et al. Blunt cerebrovascular injury incidence, stroke-rate, and mortality with the expanded Denver criteria. Surgery. 2018;164(3):494-499.
- Brommeland T, Helseth E, Aarhus M, et al. Best practice guidelines for blunt cerebrovascular injury (BCVI). Scand J Trauma Resusc Emerg Med. 2018;26(1):90.
Choicebo: The therapeutic benefits of giving patients a choice
- Just as there is a placebo effect in medicine that is well known, there is also a phenomenon called the choicebo effect, where being able to choose between two outcomes increases the likelihood that the choice will have a positive outcome.
- When there are two reasonable and equally efficacious options to offer a patient, discuss them with your patient.
- Empowering your patient to choose may increase the likelihood of that choice having a good outcome.
- Similarly, avoid the nocebo effect. If a patient has an opinion that a particular treatment will not be effective, it may decrease the likelihood that it will be effective.
- Neighbor ML, Puntillo KA. Intramuscular ketorolac vs oral ibuprofen in emergency department patients with acute pain. Acad Emerg Med. 1998;5(2):118-22.
- Bartley H, Faasse K, Horne R, Petrie KJ. You Can’t Always Get What You Want: The Influence of Choice on Nocebo and Placebo Responding. Ann Behav Med. 2016;50(3):445-51.
- Rose JP, Geers AL, Rasinski HM, Fowler SL. Choice and placebo expectation effects in the context of pain analgesia. J Behav Med. 2012;35(4):462-70.
None of the authors have any conflicts of interest to declare