Emergency treatment of asthma

Most asthma deaths occur pre-hospital raising the importance of early recognition. By Dr Andrew Bentley

Metered dose inhalers with spacer chambers can be used in the presence of a less severe exacerbation (Photograph: SPL)
Metered dose inhalers with spacer chambers can be used in the presence of a less severe exacerbation (Photograph: SPL)

Asthma is very common, with 5.4 million people in UK receiving treatment (1.1 million children and 4.3 million adults). It remains a common reason for presentation to A&E, and accounted for 1,204 deaths in the UK in 2008.

It is a heterogeneous condition with multiple triggers and clinical presentations. It is characterised by airways inflammation and mucus plugging to varying degrees, with individual responsiveness to beta-2 agonists and corticosteroids.

The excessive use of beta-2 agonists, and prescription of beta-blockers and NSAIDs are still associated with mortality from asthma. Reviews of asthma deaths have identified multiple adverse psychosocial and behavioural factors and clinical phenotypes (for example, chronic severe asthma and brittle asthma) associated with increased mortality, including:

  • Non-compliance with treatment.
  • Failure to attend appointments.
  • Fewer GP contacts/frequent home visits.
  • Obesity.
  • Alcohol or drug abuse.
  • Social isolation.
  • Financial difficulties and domestic, legal or marital stress.
  • Depression/psychiatric illness/major tranquiliser use.
  • Learning difficulties.
  • Childhood abuse.
  • History of self-discharge from hospital.

The clinician is faced with a major challenge when assessing patients presenting with acute asthma. Most asthma deaths occur pre-hospital emphasising the importance of early recognition of the features of acute severe asthma and appropriate referral to hospital.

These are described in the revised British Guideline on the Management of Asthma.1 Patients presenting with acute severe asthma in the presence of one or more of the above factors are at risk of death.

Case study
A 30-year-old female patient presents to the GP surgery with an asthma attack. Clinical records show that she has been admitted to hospital on several occasions and once to ICU within the past 12 months.

She has failed to attend follow-up hospital appointments with a chest physician following previous admissions.

On assessment she was finding it difficult to complete full sentences and had a 48-hour history of an upper respiratory illness with increasing shortness of breath and wheezing for the past six hours.

Her prescribed asthma medication was a twice-daily inhaled corticosteroid in combination with a long-acting beta-2 agonist and inhaled salbutamol. She normally used salbutamol once or twice a day but over the past two days her use had increased to eight to 10 times per day and she could not sleep because of her breathlessness and wheeze.

Rapid assessment
A rapid assessment, including a brief history and examination, should be taken without delaying urgent treatment. Previous invasive ventilation on ICU, hospital admissions within the past 12 months, repeated attendances to A&E and the use of more than three classes of asthma medication are all associated with more severe presentations of acute asthma.2

The priority of the initial assessment is to grade the severity of the exacerbation which will then dictate the decision to refer to hospital.

ASTHMA SEVERITY GRADING1
Moderate asthma Acute severe Life-threatening asthma
PEF >50-75 per
cent best or predicted
PEF 33–50 per cent
best or predicted
PEF <33 per cent
best or predicted
SpO2 ≥92 per cent SpO2 ≥92 per cent SpO2 <92 per cent
  • Speech normal
  • Respiratory rate <25/min
  • Pulse rate <110 beats per minute
  • Cannot complete sentences
  • Respiratory rate ≥25/min
  • Pulse rate ≥110 beats per minute
  • Silent chest, cyanosis or weak respiratory effort
  • Arrhythmia or hypotension
  • Exhaustion, altered consciousness

Patients with acute asthma may not be distressed; hence it is vital to make objective measurements to avoid underestimating the severity of an attack.

In a general practice setting this can be achieved by peak expiratory flow (PEF) recording compared with predicted or previous best, pulse rate and respiratory rate recording and oxygen saturation by pulse oximetry (SpO2).

Immediate management
Immediate management includes supplementary oxygen to achieve oxygen saturations >94 per cent,3 and a nebulised beta-2 agonist, such as salbutamol 5mg, driven by oxygen to reduce the risk of desaturation.

Metered dose inhalers with large volume spacer chambers can be used in the presence of a less severe exacerbation: give four puffs initially followed by two puffs every two minutes for up to 10 puffs.4

Prompt administration of oral prednisolone 40-50mg or IV hydrocortisone 100mg is essential.5 During a life-threatening attack nebulised ipratropium bromide 0.5mg can be given with the first beta-2 agonist nebuliser. It has a slower onset of action than beta-2 agonists and is then administered every four to six hours.6

Referral
There was no best peak flow recorded for the patient in her clinical records. She achieved 40 per cent predicted PEF on initial assessment with no immediate response to treatment and was now starting to show signs of exhaustion. It is clear that there is a need to arrange urgent admission.

The presence of any features of acute severe or life-threatening asthma indicates referral to hospital. The only indication for not requiring admission is a presentation without any acute severe or life-threatening features, and a sustained clinical response to initial treatment with PEF >50 per cent predicted allowing a step up in usual treatment and continuation of prednisolone.

It is wise to have a lower threshold for admission with asthma attacks in the afternoon or evening and with recent nocturnal symptoms. Administration of nebulised beta-2 agonists can be repeated immediately up to three times per hour.

It is essential to stay with the patient until the ambulance arrives. A written assessment with clinical and psychosocial history is invaluable to the admitting team.

Follow up
Following discharge from hospital, early GP review is advisable to monitor symptoms and PEF and to review inhaler technique. Ideally, a written asthma plan should be agreed with the patient, GP and chest physician to enable modification of treatment within guidelines for chronic persistent asthma and to address other potentially preventable contributors to admission.

  • Dr Bentley is a consultant in respiratory and intensive care medicine at the University Hospital of South Manchester

References
1. British Guideline on the Management of Asthma; a national clinical guideline. SIGN and British Thoracic Society, 2009.

2. Turner MO, Noertjojo K, Vedal S, et al. Risk factors for near fatal asthma. A case-control study in hospitalised patients with asthma. Am J Respir Crit Care Med 1998; 157(6 pt 1): 1804-9.

3. British Thoracic Society. Emergency oxygen use in adult patients. Thorax 2008; 63 (suppl VI).

4. Cates CJ, Crilly JA, Rowe BH. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database Syst Rev 2006; (2): CD000052.

5. Rowe BH, Spooner C, Ducharme FM, et al.

Early emergency department treatment of acute asthma with systemic corticosteroids Cochrane Database Syst Rev 2001; (1): CD002178.

6. Lanes SF, Garrett JE, Wentworth CE 3rd, et al. The effect of adding ipratropium bromide to salbutamol in the treatment of acute asthma. A pooled analysis of three trials. Chest 1998; 114(2): 365-72.

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