ANAPHYLAXIS

Allergic reaction due to mediators in a sensitised individual. It may be due to drugs, food, sera, stings and intravascular contrast media.

Clinical Features

Pruritus, Urticaria. Respiratory distress (due to laryngeal edema, bronchospasm). Hypotension.

Management

• Avoid offending agents

• Adrenaline 0.5-1 ml (children: 0.01 ml/kg) IM repeated every 10 minutes for 3 doses

• Antihistamine:

- chlorpheniramine 10 mg IV slowly. IM/SC then continued 10 mg 8 hourly for 24-48 hours (children 0.1 mg/kg)

- hydrocortisone 100 mg IV is of secondary value but useful to prevent delayed recurrences

• Aminophylline 6 mg kg IV over 20 minutes if there is wheezing

• Nebulised oxygen OR bronchodilators e.g. salbutamol

• Patients with mild to moderate reaction e.g. urticaria or mild bronchospasm should be observed for at least 6 hours because attacks may recur after full recovery.

Admit For

• Severe reactions e.g. hypotension, severe bronchospasm (especially with orally ingested antigens). Severe reactions require intravenous fluid replacement with normal saline and close monitoring especially BP and urinary output.

CARDIAC ARREST

Due to asystole, ventricular fibrillation, and cardiovascular collapse in extreme arterial hypotension. There is absence of heart sounds and of carotid and femoral pulses. There may be associated apnoea and cyanosis.

Management - General

AIRWAY Clear airway immediately. Vomitus and secretions should be aspirated or removed with fingers or handkerchief.

VENTILATION Inflate lungs with air or oxygen by mouth-to-mouth OR mouth-to-nose insufflation OR by bag and mask devices, (ensure thoracoabdominal motion).

CIRCULATION Carry out external cardiac massage (compressions) by applying appropriate pressure over the sternum. One breath should be interposed between every 4 to 5 cardiac compressions.

• For newborn or small infants effective cardiac output can be produced by applying maximum pressure with the tip of 2 fingers over middle third of the sternum. For larger infants and small children use the heel of one hand over the sternum opposite the 4th interspace

• For big children the heel of the right hand is placed over the heel of the left hand to provide the strength of both arms and shoulders

• When ventilation and massage are effective carotid and femoral pulses become palpable, pupils constrict and the colour of mucous membranes improves.

Management - Pharmacologic

• Adrenaline (1:1000) 0.5-1 ml IV/IM (children 0.01 ml/Kg) which increases myocardial contractile force

• Sodium bicarbonate IV to correct severe metabolic acidosis which develops rapidly after cessation of circulation (1.0 mEq/kg). 1 ml of 8.4% NaHCO₃ contains 1 mEq.

• Drug therapy of cardiac arrest remains controversial.

Management - Post Resuscitation Care

• Treat cause of collapse
• Monitor and regulate arterial pressure.