Catching up on CME: Random Emergency Medicine Notes (for EM doctors-in-training, or insomniacs)

https://docs.google.com/document/d/142Cj6_fbtA-3PNCL79jrMEJxFx1kzIhe_L1IAVgfxlo/edit?usp=sharing

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When a car’s airbag goes off, an electrical current hits the sodium azide inside, exploding it into nitrogen gas and hydrocarbons, and producing sodium hydroxide (lye), sodium bicarbonate, and metal oxides. When and if this dust gets into a patient’s eyes, it can cause caustic (alkali) burns. Liquefactive necrosis can take places over hours, unnoticed if the patient is unconscious, potentially destroying the cornea. So, always copiously irrigate eyes with water after an airbag deployment and pH test.

Ocular Burns and Chemical Injuries: Background, Pathophysiology, Etiology
https://emedicine.medscape.com/article/798696-overview

Rhabdomyolysis CK>6,000 associated with 50% progression to AKI.

Urine output is key in rhabdomyolysis management. After first bolusing IVFs, check serum pH, (not urine pH) to ensure urinary alkalinisation at pH>6.5.

Rhabdo is commonly associated with hypocalcemia and hyperkalemia.

Beware endoscopy on Day 5 to Day 15 in alkali/caustic esophageal burns. Risk of perforation.

Norovirus: common cause of traveler’s diarrhea, watery. 

Shiga-like E. coli (ETEC): common, bloody cause of traveler’s diarrhea, bloody.

Third-trimester painless bleeding is placental previa until proven otherwise [on exams]. Get an ultrasound before you do a digital exam.

Ultrasound misses half of placental abruptions.

Facial trauma with bloody and clear discharge, consider CSF leak.

Older patient with painless haematuria:  ddx is infection, cancer, papillary necrosis.

Esophageal varices: terlipressin/octreotide first, then balloon/endoscopy/TIPS as needed.

Boerhaave syndrome: use water-soluble gastrograffin (not barium), less mediastinitis.

Idarucizimab (Praxbind) reverses dabigatran. Hemodialysis works too, removing 60% in 2 hours. rVIIa or PCC may help too.

Hyponatremia in myxedema coma is better treated by fluid restriction than IV saline. IV thyroxine is the mainstay of myxedema treatment.

Systolic>180 or diastolic>110 + essential hypertension = ED initiation of antihypertensive (such as HCTZ)

Clindamycin actually stops toxin production in toxic shock syndrome beyond solely its bacteriostatic effect.

Bladder temperature probe (thermistor) preferred to rectal. Rectal feces can remain cool and yield inaccurate rectal temps in hypothermic patients.

Warm IV fluids are an OK way of helping prevent heat loss, but are largely ineffective at rewarming a hypothermic patient.

Heat stroke: undress, wet, and use evaporative cooling in preference to axillary ice packs.

Lidocaine is ineffective treatment for hypothermic dysrhythmias.

Phenothiazide overdoses cause sodium- and potassium-channel blockage. Sodium bicarbonate is the treatment for Na-channel blockade, may also warrant anticholinergic treatment (promethazine/diphenhydramine), benzodiazepines, and fluids.

Pacemaker problems simplified: holding a battery over the pacer unit puts it into asynchronous mode, usually a rate around 70.

Oversensing is most common problem, with the pacer causing bradycardia. Fixed (temporarily) with a magnet.

Undersensing: patient is tachycardic or has extrasystoles.

Battery failure: slow pulse, no change when you put the magnet on.

Broken wires: no change when you put the magnet on.

NMS: neuroleptic malignant syndrome. Fever, rigidity, confusion in a patient on psych meds.

Thyrotoxicosis: metoprolol is OK. Dexamethasone for thyroid storm.

Pneumocystis pneumonia: 15% have a normal chest x-ray. Trimethoprim/sulfamethoxazole is the treatment of choice.

Syphilis: initial small round painless ulcer, gone in about a month. Secondary (2-10 wks later): rash, copper-colored macules on palms and soles, condylomata lata (flat genital warts); aortitis/tabes dorsalis/etc : 10-40 years later.

Prostate cancer patient with neurological findings: suspect thoracolumbar spine metastases.

Transvaginal ultrasound is poor at identifying retroplacental clot in placental abruption.

Rectal foreign body: if bleeding, suspect possible perforation. May want to avoid anoscopy. 

X-ray prior to digital rectal exam to prevent laceration/injury to examiner.

Gabapentin, metoclopramide, and chlorpromazine are all effective treatments for intractable hiccups.

Appendicitis: RLQ pain is the most important symptom to consider, with a + likelihood ratio of 8. Followed by the findings of rigidity, and periumbilical-to-RLQ pain migration. Non-specific symptoms/signs: anorexia, fever, vomiting…except in those under 18yrs old, in which case fever carries the highest + likelihood ratio. 

A NIF (negative inspiratory force) of <30 predicts respiratory failure in Guillain-Barre syndrome.

The line between simple and febrile seizures :

>3 seizures

under six months or over six years of age

seizures longer than 30 minutes

seizures that have focal signs

seizures that are not tonic clonic

Seizure meds:

1st: 2mg lorazepam

2nd: phenytoin or fosphenytoin 

3rd: propofol/ketamine/phenobarbital 

Isolated vertical nystagmus: almost always has a central / toxic cause.

Stroke thrombolysis with rTPA: alteplase. Obtain PT/INR only if suspecting a coagulopathy.

Trauma, hypotension/shock and intraabdominal free fluid: no delay for CT, straight to OR. It’s the strongest justification to perform a FAST.

Haloperidol toxicity: seizure, fever, long QT, ventricular tachycardia

Intracranial hemorrhage: nicardipine/clevidipine preferred to control hypertension. Hydralazine causes increased ICP. Labetalol doubled infection in one 2017 study. https://pubmed.ncbi.nlm.nih.gov/28904237/

Outside 4.5 hour stroke thrombolysis window? Direct that ambulance to a comprehensive stroke center, i.e., one offering mechanical thrombectomy. They may treat out to 24 hours.

Rivaroxaban (10a inhibitor) reversed by andexanet alfa (andexxa/10a). Also give prothrombinex (efficacy uncertain).

DAWN and mechanical thrombectomy take home point: on CTA/perfusion you want a small infarcted area, a large watershed area with reduced but not absent flow, and an amenable large vessel occlusion. 

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