Wednesday Wrap-up 11/28 – Anaphylaxis, AV Node Blocks and Cardiotoxic Drugs

For those who were not in conference yesterday:

Dr. Rushabh Shah discussed AV nodal blocks:

• • For all AV blocks consider: beta blocker or calcium channel blocker overdose, hyperkalemia, inferior MI, cardiomyopathy, and myocarditis

• • 1st degree and 2nd degree Mobitz type 1 AV block: typically benign

• • 2nd degree Mobitz type 2: not benign, often caused by structural damage distal to the AV node
    • • ⅓ of patients will have asystole within a year
    • These patients need a pacemaker

• • 3rd degree AV block: similar to Mobitz type 2, need admission for permanent pacemaker

• • Treatment algorithm for patients with Mobitz type 2, 3rd degree or significant bradycardia: atropine -> transcutaneous pacing -> transvenous pacing

• Transcutaneous pacing pearls: use ultrasound to make sure the patient’s heart is actually contracting, give them analgesia because it hurts

Dr. Peter Tepler discussed RVUs:

• • RVU is basically the medical value of your services

• • Your pay = RVU x patients per hour

• • Increased complexity of medical decision-making increases RVUs: broader differential, more tests and getting extra history/chart review, higher level of patient risk

• • Critical care time increases RVUs: critical care is defined as anyone who’s condition impairs one or more organ – i.e. “everyone”

• • Procedures increase RVUs: laceration repairs, fracture reductions, nerve blocks – document everything

• Beware of up-coding that runny nose – you could be arrested for fraud

Dr. Sage Wiener discussed Cardiac Toxicity:

TCA overdose: sodium channel blockade causes QRS widening

• • QRS width: If >100ms, you’re at risk for seizure; >160ms, you are at risk for dysrhythmia
  • Look for terminal R wave in aVR to identify TCA overdose

• Treatment is sodium bicarbonate bolus: large doses of sodium to overcome the blockade
  • • Keep the ECG running during this to see if the QRS narrows; if it works, start them on bicarb drip – you get the extra sodium and the increased pH will decrease TCA affinity for the sodium channel
  • Really, you should sit at bedside and watch their monitor and when their QRS widens again, give another bolus of sodium bicarbonate

Potassium channel drugs: prolong QT which can lead to Torsades

• • If patient gets an adrenergic stimulus, i.e. heart rate suddenly increases, you can get depolarization while the heart is still repolarizing, which leads to torsades

• If patient is in Torsades: defibrillate if unstable, give magnesium, then consider a beta blocker to make sure adrenergic stimulus doesn’t happen again

Toxicologic bradycardia: beta-blocker, calcium channel blocker (diltiazem or verapamil), digoxin, clonidine and cholinergics

• • Beta blocker overdose will cause hypoglycemia and AMS

• Calcium channel will cause hyperglycemia and preserved mental status

Cocaine-related chest pain: it’s probably safe to do 2 troponin rule out, but it should be over 9-12 hours

Dr. Jennah Morgan discussed Anaphylaxis:

Definition of anaphylaxis: two or more organs involved after allergen exposure – dermatological (rash or itching), respiratory (bronchospasm), cardiovascular (hypotension), GI (nausea, vomiting, cramping, diarrhea)

• • Airway: the big concern is laryngeal edema – GIVE EPINEPHRINE and try not to intubate
    • • If you do have to intubate – consider DSI if patient is not tolerating pre-oxygenation while they are awake, use ketamine as your induction agent (1-2 mg/kg), put them on nasal cannula and nonrebreather or BiPAP to oxygenate/denitrogenate; then paralyze and intubate
    • Vent settings: patients need prolonged expiration – start with volume assist control, lung protective tidal volumes (6-8cc/kg of ideal body weight), low rate (8-10 bpm) with permissive hypercapnia (titrate to pH not CO2 level), I:E ratio should be prolonged (1.3); monitor plateau pressures not peak pressures

• • Breathing: patients can have bronchospasm, give epinephrine, can also try albuterol

• • Circulation: patients may have distributive shock, give epinephrine, can also give IV fluids
    • If hypotension is refractory to fluids and epinephrine consider giving glucagon

• Treatment: give IM epinephrine (0.01 mg/kg)
  • • Even if the patient doesn’t appear super sick right away, IM epinephrine is relatively benign
  • • Can give IV epinephrine as well in either push dose (10-50 mcg boluses) or infusion (1 mcg/kg/min for adults)
  • Other treatment: steroids and antihistamines have no proven benefit – steroids are too slow and antihistamines are too late (all the histamine is already released)

For more posts on anaphylaxis see: Anaphylaxs in the Wilderness,  How to get more doses from an Epi-pen, ED Management of Angioedema

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Charles Murchison

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