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Tricyclic Antidepressant Overdose
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Tricyclic Antidepressant Overdose
, Tricyclic Overdose
See Also
Tricyclic Antidepressant
Overdose
QRS Widening
Anticholinergic Toxicity
Symptoms
Anticholinergic Toxicity
Delirium
or confusion
Mydriasis
(dilated pupils)
Dry Mouth
Hot red skin
Signs and Symptoms
Altered Level of Consciousness
, confusion,
Delirium
or coma
Hypotension
Seizure
s
Tachycardia
Urinary Incontinence
Diagnostics
EKG Findings
R Wave
in aVR (elevation of the terminal 40 msec)
Tall
R Wave
in aVR suggests Right Ventricular Strain
QRS Widening
>0.1 s
Also seen with
Cocaine
and
Diphenhydramine
QRS >0.16 s is associated with
Seizure
s and
Dysrhythmia
s
Sinus Tachycardia
Torsades de Pointes
Labs
Venous Blood Gas
(VBG)
Obtain serial levels until stabilized
Toxicology labs
Serum
Acetaminophen
Level
Serum
Salicylate
Level
Urine Drug Screen
Avoid
Tricyclic Antidepressant
levels
TCA levels are send-out labs that do not assist in acute management
Precautions
Avoid provocative agents
Avoid
Physostigmine
Avoid Class IA
Antiarrhythmic
s (e.g.
Procainamide
, Quinine)
Avoid Class IC
Antiarrhythmic
s
Avoid barbiturates and
Phenytoin
(see
Seizure
s below)
Avoid reducing
Heart Rate
Tachycardia
decreases the
QT Interval
and is protective against
Torsades de Pointes
Management
Gene
ral
Significant risk with ingestions >10 mg/kg
Intubate early in serious Tricyclic Overdose (due to rapid decompensation)
Succinylcholine
is preferred paralytic (unless
Hyperkalemia
) less
Respiratory Acidosis
than with longer acting agent
Gastric Decontamination
if early presentation (
Activated Charcoal
, consider
Gastric Lavage
)
Management
Seizure
s
Benzodiazepine
s:
Lorazepam
(
Ativan
)
Adult:
Lorazepam
2 to 4 mg IV
Child:
Lorazepam
0.05 to 0.1 mg/kg
Avoid barbiturates
Avoid
Phenytoin
(
Dilantin
)
Management
Prolonged QRS interval (>0.1 s)
Background
Sodium Bicarbonate
mechanism
Alkalinize blood and increases drug binding, volume of distribution and drug urinary excretion
Sodium
loading helps to overcome the TCA blocking of the
Sodium
channels
Even multiple repeat doses of
Sodium Bicarbonate
are safe
Unlikely to causes significant
Hypernatremia
or
Metabolic Alkalosis
Children
Sodium Bicarbonate
1-2 mEq/kg up to 50 mEq bolus
Adults
Sodium Bicarbonate
Start: 2-4 ampules
Titrate: 2 ampules every 2 minutes until QRS narrows (may require 15-20 ampules)
Goal VBG pH 7.45 to 7.55
Other adjunctive measures
Lidocaine
(Class IB
Antiarrhythmic
)
Fast association and dissociation allows displacement of TCA from cardiac cells
Results in increased repolarization time and QRS narrowing
Ventilator
Maintain standard
Tidal Volume
s (6-8 ml/kg) at an increased
Respiratory Rate
(at least 16-18 bpm)
Adjust
Respiratory Rate
to a goal VBG pH 7.45 to 7.55
Activated Charcoal
Risk of aspiration even when intubated (do not give unless intubated with cuffed tube)
Indicated in refractory
QRS Widening
to numerous bicarbonate ampules (e.g. more than 10 ampules)
Suggests continued
Tricyclic Antidepressant
absorption (esp. if decreased GI motility)
Management
Hypotension
Tricyclic Antidepressant
s is an alpha blocker and results in
Hypotension
Goal: Low to normal
Blood Pressure
and adquate critical end-organ perfusion
Vasopressor
s
Norepinephrine
4 mg/500 cc D5W at 0.1 to 0.2 mcg/kg/min (adults - 8-12 mcg/min)
Dopamine
is not generally recommended as may exacerbate tricyclic beta mediated effects
Other measures
Consider intra-aortic balloon pump
References
(2016)
CALS
Manual, 14th ed, 1:132-3
Swadron and Nordt in Majoewsky (2013) EM:Rap 13(3):5-7
Henry (2006) Pediatr Clin North Am 53(2): 293-315 [PubMed]
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