Write it in exam oriented way.

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cd /tmp/workspace/attachments/e7df210f-02a9-4328-b6c8-fd2b6326612d && python3 -c " import pdfplumber with pdfplumber.open('TCA poisoning.pdf') as pdf: print(f'Total pages: {len(pdf.pages)}') for i, page in enumerate(pdf.pages): text = page.extract_text() print(f'--- PAGE {i+1} ---') print(text) print() "

Running Command

python3 -c " from pypdf import PdfReader import base64, json reader = PdfReader('/tmp/workspace/attachments/e7df210f-02a9-4328-b6c8-fd2b6326612d/TCA poisoning.pdf') print('Pages:', len(reader.pages)) print('Page size:', reader.pages[0].mediabox) # Check for images for i, page in enumerate(reader.pages): imgs = list(page.images) print(f'Page {i+1}: {len(imgs)} images') for img in imgs: print(f' - {img.name}, data len: {len(img.data)}') "

Running Command

python3 -c " from pypdf import PdfReader import os reader = PdfReader('/tmp/workspace/attachments/e7df210f-02a9-4328-b6c8-fd2b6326612d/TCA poisoning.pdf') os.makedirs('/tmp/workspace/tca_pages', exist_ok=True) for i, page in enumerate(reader.pages): for img in page.images: with open(f'/tmp/workspace/tca_pages/page_{i+1}.jpg', 'wb') as f: f.write(img.data) print(f'Saved page_{i+1}.jpg') "

analyse_media

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python3 -c " # Try pytesseract or other OCR import subprocess result = subprocess.run(['which', 'tesseract'], capture_output=True, text=True) print('tesseract:', result.stdout.strip() or 'not found') # Try using PIL to check image from PIL import Image img = Image.open('/tmp/workspace/tca_pages/page_1.jpg') print('Image size:', img.size, 'mode:', img.mode) "

Running Command

python3 << 'EOF' from PIL import Image img = Image.open('/tmp/workspace/tca_pages/page_1.jpg') print('Image size:', img.size, 'mode:', img.mode) # Try pytesseract try: import pytesseract text = pytesseract.image_to_string(img) print("OCR SUCCESS:") print(text[:2000]) except Exception as e: print("pytesseract error:", e) # Try easyocr try: import easyocr reader = easyocr.Reader(['en']) result = reader.readtext('/tmp/workspace/tca_pages/page_1.jpg', detail=0) print("EasyOCR result:", result[:50]) except Exception as e: print("easyocr error:", e) EOF

Running Command

pip install --user pytesseract 2>&1 | tail -3; python3 -c "import pytesseract; print('ok')" 2>&1

Running Command

python3 << 'EOF' import pytesseract from PIL import Image all_text = "" for i in range(1, 7): img = Image.open(f'/tmp/workspace/tca_pages/page_{i}.jpg') text = pytesseract.image_to_string(img) all_text += f"\n\n=== PAGE {i} ===\n{text}" print(all_text) EOF

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I now have comprehensive, authoritative content from the textbooks. Let me compile the exam-oriented note on TCA poisoning.

TCA (Tricyclic Antidepressant) Poisoning - Exam-Oriented Notes

1. OVERVIEW / HIGH-YIELD INTRO

TCAs were the mainstay of depression treatment from 1950s until SSRIs replaced them
Common agents: Amitriptyline, Imipramine, Clomipramine, Nortriptyline, Doxepin, Desipramine
Despite only 5.2% of antidepressant overdose calls to poison centers, TCAs account for 9.4% of fatalities - i.e., high lethality
Onset of toxicity: Within 1-4 hours of ingestion; onset after 6 hours is very rare
Recovery is usually rapid: within 24 hours (unless hypoxic end-organ injury has occurred)

2. MECHANISM / PATHOPHYSIOLOGY (HIGH-YIELD)

TCAs antagonize multiple receptors and ion channels - understanding each predicts clinical effects:

Target	Clinical Effect
Fast Na+ channel (cardiac)	QRS prolongation, ventricular dysrhythmias, cardiogenic shock
IKr K+ channel	QT prolongation, torsades de pointes
Alpha-1 adrenoceptor	Peripheral vasodilation, hypotension, reflex tachycardia
Muscarinic (M1) receptor	Antimuscarinic toxidrome (see below)
H1 histamine receptor	Sedation, somnolence
GABA-A receptor (antagonism)	Seizures
NE/5-HT reuptake pumps	Serotonin syndrome (rarely)

Mnemonic for TCA actions: "Na-K-M-H-Alpha-GABA" - block them all!

3. CLINICAL FEATURES (TIME-BASED - HIGH-YIELD)

Phase 1: Early (0-2 hours) - Anticholinergic Dominance

Antimuscarinic toxidrome (DUMBELLS reversed):

Delirium / confusion / agitation / hallucinations (can be comatose)
Dry mouth, anhidrosis, hot dry skin
Urinary retention
Absent bowel sounds
Mydriasis (may be absent early - competing alpha effects can keep pupils small)
Tachycardia
Rapid, mumbling speech
Early hypertension (NE reuptake block + anticholinergic)

Phase 2: Later (2-6 hours) - Cardiovascular Collapse

Hypotension (alpha-1 block + Na channel block + NE depletion)
Bradycardia (severe Na channel blockade, myocardial depression)
Seizures (GABA-A antagonism + Na channel inhibition + excess synaptic monoamines)
Coma (depressed consciousness)
Wide complex tachycardia / ventricular dysrhythmias

The classic triad of severe TCA overdose: Coma + Seizures + Wide QRS tachycardia

4. ECG FINDINGS (EXTREMELY HIGH-YIELD)

Finding	Significance
QRS < 100 ms	Low risk - patient unlikely to seize or develop dysrhythmias
QRS ≥ 100 ms	HIGH RISK - seizures and/or ventricular dysrhythmias
QRS > 160 ms	Very high risk of ventricular arrhythmia
Tall R wave in aVR (RSR' pattern in aVR)	Predicts significant toxicity - classic exam finding!
QT prolongation	Especially with Clomipramine and Amitriptyline
Sinus tachycardia	Almost universal (unless co-ingestant or moribund patient)

Key exam point: Clomipramine is especially associated with QT dispersion and mortality risk.

5. DIAGNOSIS

Clinical

Constellation of: early anticholinergic signs + decreased consciousness + seizures + wide QRS + cardiovascular collapse = highly suggestive of TCA overdose

ECG

Essential for risk stratification - do an ECG immediately
QRS width is the best predictor of severity

Labs

Serum TCA levels have NO role in managing acute poisoning - NOT predictive of severity
Serial ABG and electrolytes if treating with sodium bicarbonate
Glucose, electrolytes, renal function, LFTs

Differential Diagnosis (drugs causing wide QRS)

Class IA antiarrhythmics: quinidine, procainamide, disopyramide
Class IC antiarrhythmics: flecainide, propafenone, encainide
Diphenhydramine (also anticholinergic!)
Carbamazepine
Cocaine, amantadine, mesoridazine, thioridazine
Propoxyphene, propranolol (but cause bradycardia, not tachycardia)

Key differentiator: TCAs cause wide QRS + tachycardia + anticholinergic features - this combination is very characteristic.

6. TREATMENT (EXTREMELY HIGH-YIELD)

Step 1: Stabilize (ABC)

Airway, breathing, circulation
IV access, cardiac monitoring, pulse oximetry
Intubation frequently necessary in severe cases (profound encephalopathy, repeated seizures)

Step 2: SODIUM BICARBONATE - The Mainstay

Indications for NaHCO3:

QRS > 100 ms
Seizures
Dysrhythmias
Shock / hypotension

How it works (dual mechanism):

Sodium load - overwhelms cardiac Na channel blockade
Alkalinization - reduces TCA binding to cardiac Na channels (pH >7.45 reduces drug binding)

Dose:

Bolus: 1-2 mEq/kg IV, titrated to effect, repeat as needed
Then infusion at twice maintenance rate
Goal: QRS narrowing to <100 ms, reversal of shock
Avoid severe alkalemia: pH >7.55 is dangerous; if further treatment needed, use hypertonic saline

Step 3: Seizures

Benzodiazepines (lorazepam, diazepam) - first line (directly GABAergic)
Other directly GABAergic agents (phenobarbital) if refractory
Phenytoin is CONTRAINDICATED (sodium channel blocker - worsens toxicity)
Physostigmine is CONTRAINDICATED in TCA poisoning (asystole risk - especially in patients with bradycardia, AV block, QRS/QTc prolongation)
Flumazenil is CONTRAINDICATED (can precipitate seizures in TCA poisoning)

Step 4: Refractory Cases

Problem	Intervention
Hypotension unresponsive to NaHCO3	Norepinephrine, vasopressin
Refractory dysrhythmias/shock	Lidocaine (displaces TCA from Na channel)
Refractory shock/dysrhythmias	IV Lipid Emulsion (1.5 cc/kg bolus max 100cc, then 0.25 cc/kg/min x 20 min)
Cardiovascular collapse (last resort)	VA-ECMO

Contraindicated Treatments

Drug	Reason
Physostigmine	Asystole, especially with bradycardia/AV block
Flumazenil	Seizures
Phenytoin	Worsens Na-channel blockade
Class IA/IC antiarrhythmics	Additive Na-channel blockade
Prophylactic NaHCO3	Not indicated unless symptomatic

7. DISPOSITION

Any patient with TCA overdose requires cardiac monitoring for minimum 6 hours after ingestion
Patients who remain asymptomatic with normal ECG after 6 hours are at very low risk
Symptomatic patients require ICU admission
Patients with QRS ≥ 100 ms: admit ICU even if initially improving

8. HIGH-YIELD EXAM PEARLS (ONE-LINERS)

Most reliable predictor of severity: QRS width (not serum TCA level)
Serum TCA levels are NOT useful in acute management
Drug of choice for TCA toxicity: IV Sodium Bicarbonate
ECG sign to remember: Tall R wave / RSR' in aVR = significant toxicity
Clomipramine: Most arrhythmogenic TCA (greatest QT dispersion + mortality)
Pupils: Often small or normal despite anticholinergic features (alpha effects compete)
Never use phenytoin for seizures in TCA overdose
Physostigmine is contraindicated - risk of asystole
Onset: Toxicity begins within 1-2 hours; almost always by 6 hours
Seizures: Treat with benzodiazepines (GABAergic mechanism counters GABA-A antagonism)
Hypertonic saline can be used if alkalemia (pH >7.55) prevents further NaHCO3 dosing

9. QUICK RECALL FRAMEWORK

TCA TOXICITY = 3 Cs
   Cardiac (wide QRS, arrhythmia, shock)
   CNS (seizures, coma)
   Cholinergic block (antimuscarinic toxidrome)

TREATMENT = NaHCO3 first → Benzos for seizures → 
            NE/vasopressin if still hypotensive → 
            Lidocaine/Lipid emulsion if refractory → 
            ECMO last resort

Sources: Washington Manual of Medical Therapeutics; Rosen's Emergency Medicine, 10e - Chapter 141 (Antidepressants)

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