I had a crazy case of Tricyclic Overdose while on an overnight shift at Janus General.
Initial and Post-Treatment EKGs
List of Tricyclic Agents from Wikipedia.org
- Amitriptyline (Tryptomer, Elavil)
- Amitriptylinoxide (Amioxid, Ambivalon, Equilibrin)
- Butriptyline (Evadyne)
- Clomipramine (Anafranil)
- Demexiptiline (Deparon, Tinoran)
- Desipramine (Norpramin, Pertofrane)
- Dibenzepin (Noveril, Victoril)
- Dimetacrine (Istonil, Istonyl, Miroistonil)
- Dosulepin/Dothiepin (Prothiaden)
- Doxepin (Adapin, Sinequan)
- Imipramine (Tofranil, Janimine, Praminil)
- Imipraminoxide (Imiprex, Elepsin)
- Lofepramine (Lomont, Gamanil)
- Melitracen (Deanxit, Dixeran, Melixeran, Trausabun)
- Metapramine (Timaxel)
- Nitroxazepine (Sintamil)
- Nortriptyline (Pamelor, Aventyl, Norpress)
- Noxiptiline (Agedal, Elronon, Nogedal)
- Pipofezine (Azafen/Azaphen)
- Propizepine (Depressin, Vagran)
- Protriptyline (Vivactil)
- Quinupramine (Kevopril, Kinupril, Adeprim, Quinuprine)
Additionally…
- Amineptine (Survector, Maneon, Directim) Norepinephrine-dopamine reuptake inhibitor
- Iprindole (Prondol, Galatur, Tetran) 5-HT2 receptor antagonist
- Opipramol (Insidon, Pramolan, Ensidon, Oprimol) ? receptor agonist
- Tianeptine (Stablon, Coaxil, Tatinol) Selective serotonin reuptake enhancer
- Trimipramine (Surmontil) 5-HT2 receptor antagonist and moderate-potency norepinephrine reuptake inhibitor.
And of course, the non-TCA agents…
- Diphenhydramine
- Cocaine
- Cyclobenzaprine (I add this one to the list, b/c there can be TCA-like effects in toxicity, but it seems the potential for cardiac effects is markedly less though still possible. (J Emerg Med 1995;13(6):781-5) This one is from Bryan Hayes)
Pharmacologic Effects of TCAs
| K+ Channel Blockade | QTC Prolongation |
| NE & Serotonin Reuptake Inhibition | Initial hypertension quickly followed by hypotension |
| Na+ Channel Blockade | QRS Prolongation Hypotension — depresses myocardial contractility Ventricular dysrhythmias Brugada-like findings on EKG |
| Muscarinic Anticholinergic Receptor Antagonism | Anticholinergic Toxidrome |
| Antihistaminergic | CNS stimulation or sedation |
| Alpha1 Adrenergic Antagonism | Hypotension |
| GABA-A Receptor Blockade | Seizures |
This chart was taken from the excellent Resus Review Blog by Charles Bruen
Sodium Bicarbonate
Increases amount of drug in non-ionized form and may decrease binding to Na-channels (11482860)
May need many, many amps. For some reason the sodium and the bicarb don't rise significantly in severe toxicity
My goals are QRS duration <100, hemodynamically stable, Na ~150, pH ~7.5
Electrolyte Abnormalities
Beware of hypokalemia and hypocalcemia
Send VBG with lytes at least Q1 hour
Hyperventilation
To promote alkalosis
Hypertonic Saline
If the patient is too alkalotic or out of amps of Bicarb
Sodium Acetate
Can substitute for NaBicarb. This article gives dosing recommendations and precautions. (23636658)
Intubation & Sedation
Be very careful the patient doesn't become hypercapneic
Sedate with benzo or propofol to raise seizure threshold
Gastric Decon and/or Lavage
If time of ingestion <1 hour ago and airway is protected
We use a commercial device: the Easi-Lav system
Magnesium
May help, though risk of Torsades is low as long as the patient remains tachycardic
Lidocaine
Even though lidocaine is another Na-Channel Blocker, it actually antagonizes the effects of the TCA-like mediciations. As a Vaughan Williams Class IB agent, For additional information, this review discusses the pertinent issues.(20507243)
VasoPressors
Norepi or Epi
Intralipids
Certainly for cardiac arrest and probably for hypotension/increasing pressor necessity
For this or any other Lipid Question, you need to go immediately to the Lipid Rescue Site
You can find the Lipid Administration Instruction Sheet there, which should be hanging somewhere on the wall of your ED.
ECMO
The last resort for tox instability
Want More?
My friends Sean Nordt and Stu Swadron did a great EM:RAP episode on this 2 months ago
Here is a review and guideline article.
Shout-Outs
Medcalc sent me some freebie codes for their new IOS version of the app. Join the mailing list to be in the running (see the area below to sign up for the mailing list)
Daren Lewis of leadingvisually.com designed the wonderful Janus General logo; consider him if you need any message design.
Now on to the podcast…
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Scott Weingart
Latest posts by Scott Weingart (see all)
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Hi, my name is Scott Weingart.
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34 Comments on "Podcast 98 – Cyclic (Tricyclic) Antidepressant Overdose"
R. Garrett Hanzel writes:
Hey Scott, I didn’t see cyclobenzaprine (Flexeril) on your list. I’ve heard that its 3-ringed structure can give you +TCA on a drug screen, but I can’t find much solid evidence of whether it causes sodium channel blockade and would be managed like any other TCA overdose. Thanks for any thoughts on this.?
The literature is scant, but at least 1 article: Am J Emerg Med. 2011 Jul;29(6):645-9, indicates no TCA-like effects despite the false + on urine drug testing.
Carbamazepine, Valproic acid and phenytoin also have sodium channel blocking properties.
absolutely
Although the cyclobenzaprine structure is similar to TCA and it has the potential to cause TCA-like toxicity, overdoses usually don’t cause TCA-like cardiovascular effects. Lethargy and anticholinergic toxicity predominate. Still check in ECG. J Emerg Med 1995;13(6):781-5.
fantastic. added it to the main post.
Good podcast Scoot, I’m EP from Colombia and everytime I share your Podcast with students, residents and collegues. Thank you!
relucho@gmail.com
thanks buddy!
Great stuff as always. If you pop in an ILMA after ketamine without a paralytic, is that truly RSA? I always thought RSA was defined as induction + paralysis + SGA (without any attempt at laryngoscopy).
That antidysrhythmic rap was pure gold. Reminded me of Schoolhouse Rock!
Yeah, Bill I suppose it is not classic RSA, but gosh do I not want another acronym so I’m going to stick with it. : )
sedation-only LMA = SOLMA…?
Ugggggh!
hehehe
What is the drip rate you usually use with the bicarb drip with a TCA OD?
Great podcast as always! Thanks!
Double maintenance or to make it easy 200 ml/hr
Excellent podcast.
Say I responded to an altered patient, and did not see pill bottles indicative of a TCA-like OD laying around. And I obtained the initial ECG you posted above. I’m betting my first thought would be hyperkalemia. (Not that I’m correct and I understand the significant of the R in aVR, but to me at least it has a hyperkalemia-like QRS widening and one could convince oneself that (ie V1) the sine wave is coming.)
By our EMS protocol I would give 1 G CaCl and 1 mEq/kg Sodium Bicarb, along with possibly some Albuterol; then more CaCl and Bicarb if there was no narrowing of the QRS. So my treatment may be beneficial for the TCA OD, but could potentially contribute to some intracellular shift of the K+.
(If I was aware of TCA OD, then the ECG would prompt me to give 1-2 amps of Sodium Bicarb without the CaCl and albuterol).
Any thoughts on considering hyperkalemia from the first ECG? And the effect our hyperkalemia regimen would have on the TCA OD?
Living in the dialysis belt, I have seen much more bad hyperkalemia than TCA OD (only one comes to mind).
Thanks,
Mike
Hey Mike,
Hyperkalemia generally would not give the AMS or seizures, but if in doubt give CaCl and bicarb with no loss for either dx.
Cheers Renee. At this stage the tox folks feel intra-lipids should be given a shot for any tox-induced cardiac arrest.
Your case sounds horrible and short of ECMO, probably not much else would work.
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I’ve also read about phenytoin (good and bad). What’s your opinion on this?
The article on lidocaine above goes through the evidence for phenytoin as well. Lidocaine as edged it out as the preferred agent.
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Thanks for the interesting review. I was surprised when you said you RSI-ed this pt with succs, given the wide QRS, which could lead to a sine wave rhythm cardiac arrest. Did you consider roc or another agent?
It is a great question. The EKG didn’t look like hyperK and there was no clinical context to suspect it. If you had doubt, sure give roc. Problem with a case like this is you lose the ability to know if the pt is seizing again (which she turned out to do soon afterwards).
[…] a review on EMCrit which has a podcast, ECGs & […]
Hi,
Was wondering where you found your evidence for hyperventilation these patients. I know this is still common place in many hospitals and EMS services but very little evidence exists to prove it’s worth – some studies even suggest it results in poorer outcomes. Current guidelines on up to date don’t mention it…
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