MANAGEMENT OF ACUTE SEVERE ASTHMA

Introduction

• A life-threatening exacerbation of asthma symptoms

• Findings:

PEF (peak expiratory flow) 33-50% predicted (< 200 l/min) Respiratory rate ≥ 25/min Heart rate ≥ 110/min Arterial blood gas analysis PaO2 (N: 75-105 mm Hg)and

. PaCO2 (N: 35-45 mm Hg)

Inability to complete sentences in 1 breath

Management

• Initial assessment

• Treatment

• Mechanical ventilation

• Monitoring

Initial assessmentImmediate assessment of

ability to speak

Vital signs

Measurement of PEF is mandatory unless the

patient is too ill to cooperate

Arterial blood gas analysis

Treatment

• Oxygen

• High doses of inhaled bronchodilators

• Systemic corticosteroids

• Intravenous fluids

• Subsequent management

Treatment contd…

• Oxygen

– High concentrations of oxygen (humidified if

possible)

– Goal: SaO2 > 92%

– Failure to achieve appropriate oxygenation

assisted ventilation.

Treatment contd…

• High doses of inhaled bronchodilators

– Short-acting β2-agonists (Salbutamol 5mg/hr)

• via nebuliser driven by oxygen or via a metered

dose inhaler through a spacer device

– An inhaled anticholinergics (Ipratropium bromide

500µg) may be added

Treatment contd…

• Systemic corticosteroids

– intravenous hydrocortisone 200 mg : in patients

who are unable to swallow or vomiting.

– Oral prednisolone 40 mg

Treatment contd…

• Intravenous fluids

– To correct dehydration and acidosis

– Normal saline + sodium bicarbonate/lactate

infusion

– Potassium supplements to treat hypokalemia

induced by Salbutamol

Treatment contd…• Subsequent management– If patients fail to improve• Intravenous magnesium sulphate(1.2–2 g over 20

min)• Intravenous β2 agonists(e.g. Salbutamol) • Intravenous aminophylline (5mg/kg loading dose

over 20 minutes followed by continuous infusion at 1mg/kg/hr )• Intravenous leukotriene receptor antagonists • Anaesthetics (e.g. halothane)

Mechanical Ventilation • Initial goals– To correct hypoxaemia

– To achieve adequate alveolar ventillation

– To minimize circulatory collapse

– To buy time for medical management to work• Indications– Coma – Respiratory arrest – Deterioration of arterial blood gas tensions despite

optimal therapy – Exhaustion, confusion, drowsiness

Monitoring of treatment• PEF should be recorded every 15-30 minutes • Pulse oximetry should ensure that SaO2 remains >

92% • If aminophylline is given, then monitor the serum

concentration (therapeutic range 10–20 µg /ml)• Repeat arterial blood gases if – initial PaCO2 measurement was raised

– PaO2 was < 8 kPa (60 mmHg) or – the patient deteriorates.