Acute Severe Asthma Medication Protocol

Acute severe asthma is an attack in which the patient cannot complete sentences, has a respiratory rate of 25 or more, a heart rate of 110 or more, or a peak flow of 33 to 50 percent of best. Life-threatening features include peak flow under 33 percent, oxygen saturation under 92 percent, silent chest, cyanosis, exhaustion, arrhythmia and hypotension.

Oxygen. Target saturation of 94 to 98 percent.

Core treatment. Repeated bronchodilators, early systemic corticosteroid, and escalation to magnesium for severe or life-threatening features.

First line. Salbutamol with oxygen, ipratropium bromide, and prednisolone orally or hydrocortisone intravenously.

Second line. Intravenous magnesium sulphate. Aminophylline or intravenous salbutamol by specialist decision.

Avoid. Sedatives, and routine antibiotics without evidence of infection.

Special groups.

• Children: weight-based or age-based doses, with a spacer.

• Pregnancy: use the usual adult treatment, with oxygen and an aim of saturation 95 percent or more.

• East Africa: where nebulisers are scarce, give salbutamol by metered-dose inhaler through a spacer (a plastic bottle can be adapted), and oral prednisolone is widely available.

• Triggers: infection, smoke, NSAIDs and non-adherence.

• Salbutamol: 5 mg nebulised, repeated every 15 to 20 minutes, or continuous nebulisation of 5 to 10 mg/h. Metered-dose inhaler with spacer, 4 to 10 puffs of 100 micrograms every 10 to 20 minutes.

• Ipratropium bromide: 500 micrograms nebulised every 4 to 6 hours (every 20 minutes for the first 3 doses in severe attacks).

• Prednisolone: 40 to 50 mg orally once daily for 5 to 7 days. Hydrocortisone 100 mg intravenously every 6 hours if oral is not possible.

• Magnesium sulphate: 2 g intravenously over 20 minutes, single dose.

• Aminophylline: 5 mg/kg intravenously over 20 minutes (omit if on theophylline), then 0.5 mg/kg/h.

• Children: salbutamol 2.5 mg (under 5 years) or 5 mg (5 years and over), ipratropium 250 micrograms, prednisolone 1 to 2 mg/kg (maximum 40 mg) for 3 days, magnesium 40 mg/kg (maximum 2 g).

• Intubation: ketamine 1 to 2 mg/kg, with permissive hypercapnia and low respiratory rate.

Monitoring. Peak flow, oxygen saturation, heart rate, blood gases for life-threatening features, and potassium (salbutamol lowers it) and lactate.

Stop rules. Step down to 4-hourly bronchodilators when improving. Discharge when peak flow is over 75 percent of best, with inhaler technique checked, and a course of oral steroid.

Referral and escalation. Seek intensive care review for life-threatening features, exhaustion, rising carbon dioxide, a normal or high PaCO2, or no response after 1 hour of treatment.

Common errors. Under-treating with a single nebuliser, giving sedatives, delaying steroid, forgetting potassium, and discharging without a plan.