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tox.tca-overdose.core.v1PRODUCTION
tox.tca-overdose.core.v1

Tricyclic antidepressant overdose

toxicologyacuteadultpediatric
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Acute deliberate or accidental cyclic-antidepressant overdose; the engine exists to time-critically detect and reverse sodium-channel cardiotoxicity, seizures, and refractory hypotension [ACMT 2024]

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Cyclic agent overdose framed; deterioration window (peak risk 1–6 h) understood

Patient inputs (15)

Pediatric — one or two tablets can be lethal in a toddler; geriatric — cardiac comorbidity lowers arrhythmia threshold [ACMT 2024]

mg/kg ingested estimate (>10–20 mg/kg potentially life-threatening) and weight-based NaHCO3 / lipid-emulsion dosing [Goldfrank 2024]

Specific cyclic agent + estimated dose + co-ingestants (alcohol, benzodiazepines, SSRIs, antipsychotics) drives lethality estimate and serotonin-syndrome overlap [ACMT 2024]

Rapid clinical deterioration within 1–2 h is typical; an asymptomatic patient with normal serial ECGs at 6 h is reassuring [Liebelt 1995]

QRS duration, terminal R in aVR, R/S in aVR, QTc, rightward terminal 40 ms axis — the central prognostic surface [Boehnert & Lovejoy NEJM 1985]

Serum alkalinization target pH 7.50–7.55; acidosis increases free unbound drug and worsens sodium-channel blockade [Goldfrank 2024]

Baseline + tracks response to NaHCO3 boluses and risk of overshoot alkalosis [ACMT 2024]

Sodium load from NaHCO3 / hypertonic saline; hypernatremia is a dose-limiting toxicity [ACMT 2024]

Alkalinization drives intracellular K+ shift → hypokalemia potentiating arrhythmia; replete and monitor [Goldfrank 2024]

Mandatory co-ingestion screen in any deliberate self-poisoning [ACMT 2024]

QRS >100 ms predicts seizures; QRS >160 ms predicts ventricular arrhythmia; primary alkalinization target [Boehnert & Lovejoy NEJM 1985]

Refractory hypotension from myocardial sodium-channel blockade + alpha-blockade + reduced contractility drives fluid/pressor/bicarb escalation [ACMT 2024]

Rapid CNS depression / coma → airway protection before gastric decontamination; seizures lower pH and worsen cardiotoxicity [Goldfrank 2024]

Baseline QT-prolonging / serotonergic meds compound TCA cardiotoxicity and serotonin-syndrome risk [ACMT 2024]

Mandatory co-ingestion screen in any deliberate self-poisoning [ACMT 2024]

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (6)

6 need judgement
  • informationallife_threateningqrs_over_160ms_or_ventricular_dysrhythmia
    QRS >160 ms OR ventricular dysrhythmia / wide-complex tachycardia [Boehnert & Lovejoy NEJM 1985]
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningtca_seizure
    Seizure during TCA toxicity [Goldfrank 2024]
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningrefractory_hypotension
    Hypotension persisting after alkalinization + isotonic fluid bolus [ACMT 2024]
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningrefractory_cardiovascular_collapse
    Cardiac arrest or shock refractory to alkalinization + fluids + dual vasopressors [ACMT 2024]
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningcoma_with_airway_risk
    Rapidly progressive CNS depression / coma with airway compromise [Goldfrank 2024]
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereqrs_over_100ms
    QRS duration >100 ms (or terminal R in aVR >3 mm / R/S aVR >0.7) on ECG [Boehnert & Lovejoy NEJM 1985]
    Trigger could not be auto-evaluated — needs clinician judgement.

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RED_FLAGSoptionalDrives severity classification
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Recommended regimen

TCA overdose — serum alkalinization → seizure control → vasopressor → lipid emulsion / ECMO
axis: tca_sodium_channel_rescuestep 1 - Step 1 — Airway / breathing + serum alkalinization (keystone)
Selected step "Step 1 — Airway / breathing + serum alkalinization (keystone)" — QRS >100 ms OR terminal R in aVR >3 mm OR ventricular dysrhythmia OR hypotension OR seizure OR coma
  • sodium bicarbonate
    first line
    alkalinizing_agent / sodium_load
    1–2 mEq/kg IV bolus, repeat q3–5 min while QRS wide; then infusion 100–150 mEq in 1 L D5W titrated • IV • bolus then continuous
    triggers: qrs_over_100ms, terminal_R_aVR_over_3mm, ventricular_dysrhythmia, hypotension
    Goldfrank/ACMT 2024 — dual mechanism: sodium load overcomes fast-Na-channel blockade and alkalemia (target arterial pH 7.50–7.55) increases protein binding / favours the non-toxic uncharged drug; titrate to QRS <100 ms, not to a fixed dose
    rxcui 36676
  • hypertonic saline (3%)
    second line
    sodium_load
    100–250 mL IV • IV • PRN if QRS remains wide despite NaHCO3 and pH at ceiling
    triggers: qrs_wide_despite_bicarb, arterial_pH_at_7.55_ceiling, severe_hypernatremia_limiting_bicarb
    ACMT 2024 — when alkalinization is maximised but QRS stays wide, additional sodium loading without further raising pH can narrow the QRS; monitor Na+ closely
    rxcui 9863

ed playbook — drug actions (6)

  1. 1. sodium bicarbonate bolus
    1–2 mEq/kg IV, repeat q3–5 min while QRS wide • IV • bolus, repeat PRN
    trigger: QRS >100 ms OR terminal R aVR >3 mm OR dysrhythmia OR hypotension OR seizure
    Keystone — titrate to QRS <100 ms + arterial pH 7.50–7.55 [Goldfrank/ACMT 2024]
  2. 2. sodium bicarbonate infusion
    100–150 mEq in 1 L D5W titrated • IV • continuous after boluses
    trigger: After initial QRS narrowing
    Maintain alkalemia/sodium load; watch for re-widening [ACMT 2024]
  3. 3. lorazepam (or diazepam)
    Lorazepam 2–4 mg IV (diazepam 5–10 mg IV) repeat PRN • IV • PRN
    trigger: Seizure
    First-line; aborts seizure-driven acidosis [Goldfrank 2024]
  4. 4. isotonic crystalloid
    10–20 mL/kg IV bolus, reassess • IV • bolus, reassess
    trigger: Hypotension
    First volume step; cautious for reduced contractility [ACMT 2024]
  5. 5. norepinephrine
    0.05–0.5 mcg/kg/min IV titrated to MAP ≥65 • IV • continuous
    trigger: Hypotension after fluids + alkalinization
    Direct alpha counters TCA alpha-blockade [Goldfrank/ACMT 2024]
  6. 6. lipid emulsion 20%
    1.5 mL/kg IV bolus then 0.25–0.5 mL/kg/min • IV • bolus then infusion
    trigger: Refractory collapse / peri-arrest
    Rescue lipid sink; does not replace alkalinization [ACMT 2024]

Auto-drafted A&P note

ed

Subjective

- Possible entry pathways: Reported or suspected TCA / cyclic antidepressant ingestion (amitriptyline, nortriptyline, imipramine, clomipramine, doxepin, dosulepin) [AACT/EAPCCT; ACMT 2024]; QRS >100 ms or terminal R wave in aVR >3 mm on ECG [Boehnert & Lovejoy NEJM 1985; Liebelt 1995]; Anticholinergic toxidrome + seizure / coma / hypotension cluster [Goldfrank 2024].

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Tricyclic antidepressant overdose** (tox.tca-overdose.core.v1).
Phenotype framing: Differentiate from other sodium-channel-blocking xenobiotics (Class IA/IC, diphenhydramine, bupropion, propranolol, carbamazepine, cocaine), pure anticholinergic toxidrome, sympathomimetic toxidrome, serotonin syndrome, hyperkalemia, and primary VT [Goldfrank 2024; ACMT 2024]
Scope: Acute deliberate or accidental cyclic-antidepressant overdose; the engine exists to time-critically detect and reverse sodium-channel cardiotoxicity, seizures, and refractory hypotension [ACMT 2024]

No severity triggers fired against current inputs.

Plan

Regimen axis: **TCA overdose — serum alkalinization → seizure control → vasopressor → lipid emulsion / ECMO** — step "Step 1 — Airway / breathing + serum alkalinization (keystone)".
1. sodium bicarbonate 1–2 mEq/kg IV bolus, repeat q3–5 min while QRS wide; then infusion 100–150 mEq in 1 L D5W titrated IV bolus then continuous (alkalinizing_agent / sodium_load, first line) — Goldfrank/ACMT 2024 — dual mechanism: sodium load overcomes fast-Na-channel blockade and alkalemia (target arterial pH 7.50–7.55) increases protein binding / favours the non-toxic uncharged drug; titrate to QRS <100 ms, not to a fixed dose
2. hypertonic saline (3%) 100–250 mL IV IV PRN if QRS remains wide despite NaHCO3 and pH at ceiling (sodium_load, second line) — ACMT 2024 — when alkalinization is maximised but QRS stays wide, additional sodium loading without further raising pH can narrow the QRS; monitor Na+ closely

Setting playbook (ed) — Resuscitation-bay management: secure airway, capture 12-lead, start serum alkalinization to QRS narrowing, control seizures, support hemodynamics, stage rescue tiers, disposition to ICU [ACMT 2024]
3. sodium bicarbonate bolus 1–2 mEq/kg IV, repeat q3–5 min while QRS wide IV bolus, repeat PRN — QRS >100 ms OR terminal R aVR >3 mm OR dysrhythmia OR hypotension OR seizure (Keystone — titrate to QRS <100 ms + arterial pH 7.50–7.55 [Goldfrank/ACMT 2024])
4. sodium bicarbonate infusion 100–150 mEq in 1 L D5W titrated IV continuous after boluses — After initial QRS narrowing (Maintain alkalemia/sodium load; watch for re-widening [ACMT 2024])
5. lorazepam (or diazepam) Lorazepam 2–4 mg IV (diazepam 5–10 mg IV) repeat PRN IV PRN — Seizure (First-line; aborts seizure-driven acidosis [Goldfrank 2024])
6. isotonic crystalloid 10–20 mL/kg IV bolus, reassess IV bolus, reassess — Hypotension (First volume step; cautious for reduced contractility [ACMT 2024])
7. norepinephrine 0.05–0.5 mcg/kg/min IV titrated to MAP ≥65 IV continuous — Hypotension after fluids + alkalinization (Direct alpha counters TCA alpha-blockade [Goldfrank/ACMT 2024])
8. lipid emulsion 20% 1.5 mL/kg IV bolus then 0.25–0.5 mL/kg/min IV bolus then infusion — Refractory collapse / peri-arrest (Rescue lipid sink; does not replace alkalinization [ACMT 2024])

Non-pharmacologic actions:
- RSI with controlled hyperventilation for coma / airway compromise — avoid hypercapnic acidosis [Goldfrank 2024]
- Single-dose activated charcoal 1 g/kg only if early presentation AND airway protected [AACT/EAPCCT]
- Continuous cardiac monitor + SpO2 + capnography if intubated [ACMT 2024]
- Two large-bore IVs; central access if vasopressors required [ACMT 2024]
- Do NOT give Class IA/IC/III antiarrhythmics, phenytoin, flumazenil, physostigmine, or beta-blockers [Goldfrank 2024; ACMT 2024]
- Early poison-centre / medical-toxicology consult [ACMT 2024]

AVOID / contraindication checks:
- Avoid_class_IA_antiarrhythmics_quinidine_procainamide_disopyramide_additive_sodium_channel_blockade (Goldfrank 2024)
- Avoid_class_IC_antiarrhythmics_flecainide_propafenone_additive_sodium_channel_blockade (Goldfrank 2024)
- Avoid_class_III_antiarrhythmics_amiodarone_sotalol_qt_prolongation (Goldfrank 2024)
- Avoid_phenytoin_for_seizures_class_IB_like_ineffective_may_worsen_cardiotoxicity (ACMT 2024)
- Avoid_flumazenil_precipitates_seizures_and_unmasks_proconvulsant_tca_effect (ACMT 2024)
- Avoid_physostigmine_asystole_and_seizures_reported_in_tca_toxicity (ACMT 2024)
- Avoid_beta_blockers_for_tachycardia_unmask_alpha_mediated_hypotension (Goldfrank 2024)
- Avoid_respiratory_or_metabolic_acidosis_increases_free_drug_and_channel_blockade (Goldfrank 2024)
- Do_not_force_activated_charcoal_in_unprotected_airway (AACT/EAPCCT)
- Cap_arterial_pH_at_7.55_to_avoid_overshoot_alkalosis_and_hypokalemia (ACMT 2024)

Monitoring

Regimen monitoring:
- continuous telemetry and serial 12 lead ecg qrs and terminal R aVR trend (Boehnert & Lovejoy NEJM 1985)
- arterial pH q1-2h during alkalinization ceiling 7.55 (ACMT 2024)
- K q2h alkalinization driven hypokalemia potentiates arrhythmia (Goldfrank 2024)
- Na monitoring with bicarb and hypertonic saline loads (ACMT 2024)
- neuro checks q1h for recurrent seizure or re-deterioration (Goldfrank 2024)
- capnography if intubated avoid hypoventilation (Goldfrank 2024)
- serum lactate and CK if seizures or prolonged hypotension (ACMT 2024)
- observe for post bolus QRS re-widening and delayed deterioration (Liebelt 1995)

Setting (ed) monitoring:
- Continuous telemetry + serial 12-lead ECG q15–30 min until QRS normal [Boehnert & Lovejoy NEJM 1985]
- ABG q1–2h during alkalinization (arterial pH ceiling 7.55) [ACMT 2024]
- K+ q2h, Na+ with each Na load [Goldfrank 2024]
- GCS / seizure surveillance q1h [Goldfrank 2024]

Follow-up plan: Psychiatry safety plan and means-restriction counselling for intentional ingestion, PCP medication reconciliation (limit TCA dispensed quantity / switch to safer agent), social work, neurology if anoxic injury, cardiology if persistent conduction abnormality [ACMT 2024]
- Close-out criterion: Safety plan, prescribing review, and follow-up documented

Monitoring phase: Continuous telemetry + serial 12-lead ECG (QRS / terminal-R-aVR trend), ABG q1–2h during active alkalinization, K+ q2h (alkalinization-driven hypokalemia), arterial pH ceiling 7.55, neuro checks q1h, capnography if intubated, watch for delayed deterioration and post-bolus re-widening [Goldfrank 2024]

Disposition

Current setting: ed — Resuscitation-bay management: secure airway, capture 12-lead, start serum alkalinization to QRS narrowing, control seizures, support hemodynamics, stage rescue tiers, disposition to ICU [ACMT 2024]

Disposition criteria:
- ICU: any QRS prolongation, seizure, dysrhythmia, hypotension, AMS, or ongoing NaHCO3 infusion [ACMT 2024]
- Medically cleared for psychiatry: asymptomatic with normal serial ECGs + normal mental status at ≥6 h post-ingestion [ACMT 2024]
- Psychiatry consult mandatory for all intentional ingestions [ACMT 2024]

Escalation triggers (move to higher acuity):
- QRS persistently >100 ms despite alkalinization → ICU + hypertonic saline / lipid emulsion [ACMT 2024]
- Ventricular dysrhythmia / cardiac arrest → ICU + lipid emulsion + consider VA-ECMO [ACMT 2024]
- Refractory hypotension on dual vasopressors → ICU + lipid emulsion / mechanical support [ACMT 2024]
- Status epilepticus → ICU + propofol + intubation (NOT phenytoin) [ACMT 2024]

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] QRS >160 ms OR ventricular dysrhythmia / wide-complex tachycardia [Boehnert & Lovejoy NEJM 1985]
- [LIFE_THREATENING] Seizure during TCA toxicity [Goldfrank 2024]
- [LIFE_THREATENING] Hypotension persisting after alkalinization + isotonic fluid bolus [ACMT 2024]

Citations

- AACT/EAPCCT decontamination position papers + Goldfrank's Toxicologic Emergencies 11th ed (cyclic antidepressants) + 2024 ACMT lipid-emulsion workgroup + Boehnert & Lovejoy NEJM 1985 QRS / terminal-R-aVR seizure & arrhythmia thresholds + Liebelt 1995 aVR criterion [PMID:3969674](https://pubmed.ncbi.nlm.nih.gov/3969674/)
- Cited evidence (PMID 7715035) [PMID:7715035](https://pubmed.ncbi.nlm.nih.gov/7715035/)
- Cited evidence (PMID 3057117) [PMID:3057117](https://pubmed.ncbi.nlm.nih.gov/3057117/)
- Cited evidence (PMID 23590707) [PMID:23590707](https://pubmed.ncbi.nlm.nih.gov/23590707/)
- Cited evidence (PMID 26594093) [PMID:26594093](https://pubmed.ncbi.nlm.nih.gov/26594093/)

Last reconciled with current guidelines: 2026-05-16.
References
  • AACT/EAPCCT decontamination position papers + Goldfrank's Toxicologic Emergencies 11th ed (cyclic antidepressants) + 2024 ACMT lipid-emulsion workgroup + Boehnert & Lovejoy NEJM 1985 QRS / terminal-R-aVR seizure & arrhythmia thresholds + Liebelt 1995 aVR criterion — PMID:3969674
  • Cited evidence (PMID 7715035) — PMID:7715035
  • Cited evidence (PMID 3057117) — PMID:3057117
  • Cited evidence (PMID 23590707) — PMID:23590707
  • Cited evidence (PMID 26594093) — PMID:26594093