Study Group

Tricyclic antidepressants most common)
*Type Ia antiarrhythmics (quinidine, procainamide)
*Type Ic antiarrhythmics (flecainide, encainide)
*Local anaesthetics (bupivacaine, ropivacaine)
*Antimalarials (chloroquine, hydroxychloroquine)
*Dextropropoxyphene
*Propranolol
*Carbamazepine
*Quinine


In overdose, the tricyclics produce rapid onset (within 1-2 hours) of:
Sedation and coma
Seizures
Hypotension
Tachycardia
Broad complex dysrhythmias
Anticholinergic syndrome
Tricyclics mediate their cardiotoxic effects via blockade of myocardial fast sodium channels (QRS prolongation, tall R wave in aVR), inhibition of potassium channels (QTc prolongation) and direct myocardial depression.
Other toxic effects are produced by blockade at muscarinic (M1), histamine (H1) and α1-adenergic receptors. The degree of QRS broadening on the ECG is correlated with adverse events:
QRS > 100 ms is predictive of seizures
QRS > 160 ms is predictive of ventricular arrhythmias (e.g. VT)
:
*Interventricular conduction delay — QRS > 100 ms in lead II
*Right axis deviation of the terminal QRS:
*Terminal R wave > 3 mm in aVR
*R/S ratio > 0.7 in aVR
Patients with tricyclic overdose will also usually demonstrate *sinus tachycardia secondary to muscarinic (M1) receptor
Overdose >10mg/kg with Signs of cardiotoxicity (ECG changes)
Patients need to be managed in a monitored area equipped for airway management and resuscitation.
Secure IV access, administer high flow oxygen and attach monitoring equipment.
Administer IV sodium bicarbonate 100 mEq (1-2 mEq / kg); repeat every few minutes until BP improves and QRS complexes begin to narrow.
Intubate as soon as possible.
Hyperventilate to maintain a pH of 7.50 – 7.55.
Once the airway is secure, place a nasogastric tube and give 50g (1g/kg) of activated charcoal.
Treat seizures with IV benzodiazepines (e.g. diazepam 5-10mg).
Treat hypotension with a crystalloid bolus (10-20 mL/kg). If this is unsuccessful in restoring BP then consider starting vasopressors (e.g. noradrenaline infusion).
If arrhythmias occur, the first step is to give more sodium bicarbonate. Lidocaine (1.5mg/kg) IV is a third-line agent (after bicarbonate and hyperventilation) once pH is > 7.5.
Avoid Ia (procainamide) and Ic (flecainide) antiarrhythmics, beta-blockers and amiodarone as they may worsen hypotension and conduction abnormalities.
Admit the patient to the intensive care unit for ongoing management.blockade.

Study Group Internal medicine

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This maneuver is achieved by having the patient elevate both arms until they touch the sides of the face. A positive Pemberton's sign is marked by the presence of facial congestion and cyanosis, as well as respiratory distress after approximately one minute... the sign is used to evaluate SVC obstruction due to various causes like
​ are :-
*Bronchogenic Carcinoma.
*Lymphoma.
*Retrosternal Goiter.
*Mediastinal mass.