ACUTE SEVERE ASTHMA

Recognition

Definition

• “It is a disease characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from person to person” (WHO).
• “This condition is due to inflammation of the air passages in the lungs and affects the sensitivity of the nerve endings in the airways so they become easily irritated. In an attack, the lining of the passages swell causing the airways to narrow and reducing the flow of air in and out of the lungs.” (WHO).

History

If possible, ascertain if patient has:

• Previous admissions with exacerbation of asthma
• Any history of eczema or hayfever
• Any admissions to Intensive Care Unit (ITU)
• Any allergies

General symptoms

• Shortness of breath (dyspnoea)
• Cyanosis
• Cough (often worse at night, cold air, exercise)
• Chest tightness

General Signs

• Tachypnoea
• Low Oxygen saturations
• Use of accessory muscles for breathing
• Wheeze

Severity (SIGN guidance 2016)

Moderate Acute Asthma

• Increasing symptoms
• Peak Expiratory Flow (PEFR) > 50 - 75% of best or predicted
• No features of acute severe asthma

Acute Severe Asthma

Any one of:

• Respiratory rate ≥ 25 breaths/minute
• Heart rate ≥ 110 beats/minute
• Inability to complete sentences in one breath
• PEFR 33 - 55% of best or predicted

Life-Threatening Asthma

In a patient with severe asthma and one of:

• Oxygen saturations < 92% on air
• Arterial partial pressure of oxygen (PaO₂) < 8 kPa. Result from arterial blood gas
• Normal partial pressure of Carbon Dioxide (PaCO₂) 4.6 - 6.0 kPa
• Silent chest
• Cyanosis
• Poor respiratory effort
• Arrhythmia
• Hypotension
• Exhaustion
• Altered conscious level
• PEFR < 33% of best or predicted

Near-Fatal Asthma

One of both of:

• Raised PaCO₂
• Requiring mechanical ventilation with raised inflation pressures

Initial Assessment and Investigations

• ABCDE assessment
• Sit patient up if able to tolerate
• Assess patient’s airway
• Monitor oxygen saturations and respiratory rate
• If patient is hypoxic give Oxygen (O₂) to achieve target saturations. Initially give 15 L/min via a reservoir mask if the patient is acutely unwell
• Target saturations:
• 94 - 98% for patients not at risk of hypercapnic respiratory failure
• 88 - 92% for patients at risk of hypercapnic respiratory failure due to conditions such as Chronic Obstructive Pulmonary Disease (COPD)
• Call for senior help
• Examine patient’s chest
• Listening for:
• Wheeze
• Silent chest
• Crackles
• Hyper - resonant (In pneumothorax)
• PEFR, if patient is able to perform this
• Arterial blood gas (ABG)
• Low 0₂ and increasing CO₂ is Type 2 Respiratory Failure and may be a sign that the patient is tiring. For further information see “Response” Section in “Breathing” Chapter
• Chest X-ray if:
• You suspect
• Pneumothorax
• Consolidation
• Life-threatening asthma
• There is:
• Failure to respond to treatment satisfactorily
• Requirement for ventilation
• If the patient is unwell this will need to be a portable X-ray
• Obtain intravenous (IV) access by placing 2 large bore cannulae in the antecubital fossa. Take blood to check Full Blood Count (FBC), Urea and Electrolytes (U&Es), C-Reactive Protein (CRP), Liver function tests (LFTs), Glucose
• Check Capillary Refill Time (CRT) - hold for five seconds and refilling should occur in 3 seconds
• Assess pulse rate, rhythm and character
• Monitor heart rate and blood pressure
• Listen to patient’s heart sounds
• Consider sepsis six if sepsis suspected. For further information see “Sepsis” Section in “Medical Emergencies” Chapter.
• Electrocardiogram (ECG) if patient tachycardic or abnormal rhythm palpated
• Check pupils are equal and reactive
• Assess Glasgow Coma Scale or ACVPU using the NEWS2 chart
• Check patient’s temperature and blood sugar
• Examine patient’s abdomen and legs
• Consider venous thromboembolism prophylaxis

Response

Management

Immediate management

• Steroids
• Hydrocortisone 100 mg intravenously (IV) or Prednisolone 40 mg orally (PO)

• Bronchodilators
• Salbutamol 5 mg nebulised with ~6 – 7 L/min Oxygen. If patient is requiring Oxygen at 15 L/min via reservoir mask to maintain saturations, then consider giving the patient supplemental oxygen via nasal cannula whilst they are receiving the nebuliser
• Repeat as required. May need to be back to back.
• Ipratropium Bromide 500 micrograms nebulised with oxygen as above. This can be given 4 - 6 hrly

• Additional therapies
• Consider Magnesium Sulphate in patients with acute severe asthma. Give a single dose of 1.2 - 2 g IV of Magnesium Sulphate over 20 minutes

Referrals

• Additional therapies
• Discuss with senior member of the team
• Contact critical care outreach team
• Referral to the Respiratory team
• Referral to physiotherapy team
• Consider referral to Intensive Care Unit (ICU) if:
• Failure to respond to treatment satisfactorily
• Patient requires ventilator support
• Patient requires blood pressure support
• Deterioration of blood gas following medical management

Future management

• Patient may require review of current medications