Acute asthma in adults

Asthma pathway (BTS, NICE, SIGN) [SIGN 244]

This content is from the BTS/SIGN British guideline on the management of asthma (SIGN 158), 2019.

 

      

Initial Assessment

See asthma treatment algorithms - acute severe or life-threatening asthma in:

 

Recognition of acute asthma

Definitions of increasing levels of severity of acute asthma attacks are provided in the table below. Predicted PEF values should be used only if the recent best PEF (within two years) is unknown.

Self treatment by patients developing acute or uncontrolled asthma

Patients with asthma, and all patients with severe asthma, should have an agreed written PAAP and their own peak-flow meter, with regular checks of inhaler technique and adherence. They should know when and how to increase their medication and when to seek medical assistance. Written PAAPs can decrease hospitalisation for,166 and deaths from asthma (see the section on self-management).573

Initial assessment 

All possible initial contact personnel, for example practice receptionists, ambulance call takers, NHS 111 (England and Wales), NHS 24 (Scotland), and out-of-hours providers, should be aware that asthma patients complaining of respiratory symptoms are at risk of becoming seriously unwell very quickly. Such patients
should have immediate access to a healthcare professional trained in the emergency treatment of asthma. The assessments required to determine whether the patient is suffering from an acute attack of asthma, the severity of the attack and the nature of treatment required are detailed in the tables below. It may be helpful to use a systematic recording process. Proformas have proved useful in the ED setting.574

Levels of severity of acute asthma attacks in adults

Moderate acute asthma

  • Increasing symptoms
  • PEF >50–75% best or predicted
  • No features of acute severe asthma.

Acute severe asthma

Any one of:

  • PEF 33–50% best or predicted
  • respiratory rate ≥25/min
  • heart rate ≥110/min
  • inability to complete sentences in one breath.

Life-threatening asthma

Any one of the following in a patient with severe asthma:

Clinical signs

Measurements

Altered conscious level

PEF <30% best or predicted

Exhaustion

SpO2 <92%

Arrhythmia

PaO2 <8 kPa

Hypotension

’normal’ PaCO2 (4.6–6.0 kPa)

Cyanosis

 

Silent chest

 

Poor respiratory effort

 

Near-fatal asthma

Raised PaCO2 and/or requiring mechanical ventilation with raised inflation pressures

  • SpO2: oxygen saturation measured by a pulse oximeter
  • PaO2: partial arterial pressure of oxygen
  • kPa: kilopascals
  • PaCO2: partial arterial pressure of carbon dioxide

 

Prevention of acute deterioration

A register of patients at risk may help healthcare professionals in primary care to identify patients who are more likely to die from their asthma. A system should be in place to ensure that these patients are contacted if they fail to attend for follow up.

Criteria for referral

 

R
Refer to hospital any patients with features of acute severe or life-threatening asthma.

[BTS/SIGN 2019]

Other factors, such as failure to respond to treatment, social circumstances or concomitant disease, may warrant hospital referral.

Initial assessment of symptoms, signs and measurements

Clinical features

Clinical features can identify some patients with severe asthma, eg severe breathlessness (including too breathless to complete sentences in one breath), tachypnoea, tachycardia, silent chest, cyanosis, accessory muscle use, altered consciousness or collapse.566-571, 575

None of these singly or together is specific. Their absence does not exclude a severe attack.

PEF or FEV

Measurements of airway calibre improve recognition of the degree of severity, the appropriateness or intensity of therapy, and decisions about management in hospital or at home.576, 577

PEF or FEV1 are useful and valid measures of airway calibre. PEF is more convenient in the acute situation. PEF expressed as a percentage of the patient’s previous best value is most useful clinically. PEF as a percentage of predicted gives a rough guide in the absence of a known previous best value. Different peak-flow meters give different readings. Where possible the same or similar type of peak-flow meter should be used.

Pulse oximetry

Measure oxygen saturation (SpO2) with a pulse oximeter to determine the adequacy of oxygen therapy and the need for arterial blood gas measurement. The aim of oxygen therapy is to maintain SpO2 94–98%.578

Blood gases

Patients with SpO2 <92% (irrespective of whether the patient is on air or oxygen) or other features of life-threatening asthma require arterial blood gas measurement.566-569, 571, 579 SpO2 <92% is associated with a risk of hypercapnia. Hypercapnia is not detected by pulse oximetry.579 In contrast, the risk of hypercapnia with SpO2 >92% is much less.578

Chest X-ray

Chest X-ray is not routinely recommended in the absence of:

  • suspected pneumomediastinum or pneumothorax
  • suspected consolidation
  • life-threatening asthma
  • failure to respond to treatment satisfactorily
  • requirement for ventilation.

Systolic paradox

Systolic paradox (pulsus paradoxus) is an inadequate indicator of the severity of an attack and should not be used.566-571, 580

 

Criteria for admission

Adult patients with any feature of a life-threatening or near-fatal asthma attack or a severe asthma attack that does not resolve after initial treatment should be admitted to hospital. Admission may also be appropriate when peak flow has improved to greater than 75% best or predicted one hour after initial treatment but concerns remain about symptoms, previous history or psychosocial issues (see Lessons from asthma deaths and near-fatal asthma).556, 558, 566-571

 

R
Admit patients with any feature of a life-threatening or near-fatal asthma attack.

[BTS/SIGN 2019]

 

R
Admit patients with any feature of a severe asthma attack persisting after initial treatment.

[BTS/SIGN 2019]

 

R
Patients whose peak flow is greater than 75% best or predicted one hour after initial treatment may be discharged from ED unless they meet any of the following criteria, when admission may be appropriate:
  • still have significant symptoms
  • concerns about adherence
  • living alone/socially isolated
  • psychological problems
  • physical disability or learning difficulties
  • previous near-fatal asthma attack
  • asthma attack despite adequate dose of oral corticosteroid prior to presentation
  • presentation at night
  • pregnancy.

[BTS/SIGN 2019]

 

Management of acute asthma in adults in general practice

Many deaths from asthma are preventable. Delay can be fatal. Factors leading to poor outcome include:

  • Clinical staff failing to assess severity by objective measurement
  • Patients or relatives failing to appreciate severity
  • Under use of corticosteroids

Regard each emergency asthma consultation as for acute severe asthma until shown otherwise

Assess and record:

  • Peak expiratory flow (PEF)
  • Symptoms and response to self treatment
  • Heart and respiratory rates
  • Oxygen saturation (by pulse oximetry)

Caution: Patients with severe or life-threatening attacks may not be distressed and may not have all the abnormalities listed below. The presence of any should alert the doctor.

Initial assessment

  • PEF>50–75% best or predicted - moderate asthma
  • PEF 33–50% best or predicted - acute severe asthma
  • PEF<33% best or predicted - life-threatening asthma

Further assessment

Moderate asthma:

  • SpO2 ≥92%
  • Speech normal
  • Respiration <25 breaths/min
  • Pulse <110 beats/min.

Acute severe asthma:

  • SpO2 ≥92%
  • Can’t complete sentences
  • Respiration ≥25 breaths/min
  • Pulse ≥110 beats/min.

Life-threatening asthma:

  • SpO2 <92%
  • Silent chest, cyanosis or poor respiratory effort
  • Arrhythmia or hypotension
  • Exhaustion, altered consciousness.

 

Management and Treatment

Moderate asthma:

Treat at home or in surgery and assess response to treatment.

  • β2 bronchodilator:
    • via spacer*
  • If no improvement:
    • via nebuliser (preferably oxygen-driven), salbutamol 5 mg
  • Give prednisolone 40–50 mg
  • Continue or increase usual treatment
  • If good response to first treatment (symptoms improved, respiration and pulse settling and PEF >50%) continue or increase usual treatment and continue prednisolone.

Admit to hospital if any:

  • Life-threatening features
  • Features of acute severe asthma present after initial treatment
  • Previous near-fatal asthma

Lower threshold for admission if afternoon or evening attack, recent nocturnal symptoms or hospital
admission, previous severe attacks, patient unable to assess own condition, or concern over social circumstances.

Acute Severe asthma:

Consider admission.

  • Oxygen to maintain SpO2 94–98% if available
  • β2 bronchodilator:
    • via nebuliser (preferably oxygen-driven), salbutamol 5 mg
    • or if nebuliser not available, via spacer*
  • Prednisolone 40–50 mg or IV hydrocortisone 100 mg
  • If no response in acute severe asthma: ADMIT.

If admitting the patient to hospital:

  • Stay with patient until ambulance arrives
  • Send written assessment and referral details to hospital
  • β2 bronchodilator via oxygen-driven nebuliser in ambulance.

Life-threatening asthma:

Arrange immediate admission.

  • Oxygen to maintain SpO2 94–98%
  • β2 bronchodilator with ipratropium:
    • via nebuliser (preferably oxygen-driven), salbutamol 5 mg and
      ipratropium 0.5mg
    • or if nebuliser and ipratropium not available, β2 bronchodilator via spacer*
  • Prednisolone 40–50 mg or IV hydrocortisone 100 mg immediately.

Follow up after treatment or discharge from hospital:

  • Continue prednisolone until recovery (minimum 5 days)
  • GP review within 2 working days
  • Monitor symptoms and PEF
  • Check inhaler technique
  • Written asthma action plan
  • Modify treatment according to guidelines for chronic persistent asthma
  • Address potentially preventable contributors to admission.

 

* β2 bronchodilator via spacer given one puff at a time, inhaled separately using tidal breathing; according to response, give another puff every 60 seconds up to a maximum of 10 puffs

References

  1. 166. Gibson PG, Powell H, Coughlan J, Wilson AJ, Abramson M, Haywood P, et al. Self-management education and regular practitioner review for adults with asthma (Cochrane Review). In: The Cochrane Library, 2003.
  2. 555. Rea HH, Scragg R, Jackson R, Beaglehole R, Fenwick J, Sutherland DC. A case-control study of deaths from asthma. Thorax 1986;41(11):833-9.
  3. 556. Campbell MJ, Cogman GR, Holgate ST, Johnston SL. Age specific trends in asthma mortality in England and Wales, 1983-95: results of an observational study. BMJ 1997;314(7092):1439-41.
  4. 557. Richards GN, Kolbe J, Fenwick J, Rea HH. Demographic characteristics of patients with severe life threatening asthma: comparison with asthma deaths. Thorax 1993;48(11):1105-9.
  5. 558. Innes NJ, Reid A, Halstead J, Watkin SW, Harrison BD. Psychosocial risk factors in near-fatal asthma and in asthma deaths. J R Coll Physicians Lond 1998;32(5):430-4.
  6. 566. British Thoracic Society, National Asthma Campaign, Royal College of Physicians of London in association with the General Practitioner in Asthma Group, The British Association of Accident and Emergency Medicine, The British Paediatric Respiratory Society, Royal College of Paediatrics and Child Health. The British guidelines on asthma management 1995 review and position statement. Thorax 1997;52(Suppl 1):S1-S21.
  7. 567. Scottish Intercollegiate Guidelines Network (SIGN). Emergency management of acute asthma. Edinburgh: SIGN; 1999. (SIGN publication no. 38). [cited
  8. 568. International consensus report on the diagnosis and treatment of asthma. National Heart, Lung, and Blood Institute, National Institutes of Health. Bethesda, Maryland 20892. Publication no. 92- 3091, March 1992. Eur Respir J 1992;5(5):601-41.
  9. 569. Neville E, Gribbin H, Harrison BD. Acute severe asthma. Respir Med 1991;85(6):463-74.
  10. 570. Brenner B, Kohn MS. The acute asthmatic patient in the ED: to admit or discharge. Am J Emerg Med 1998;16(1):69-75.
  11. 571. Boulet LP, Becker A, Berube D, Beveridge R, Ernst P. Canadian asthma consensus report, 1999. Canadian asthma consensus group. CMAJ 1999;161(11 Suppl):S1-61.
  12. 573. Abramson MJ, Bailey MJ, Couper FJ, Driver JS, Drummer OH, Forbes AB, et al. Are asthma medications and management related to deaths from asthma? Am J Respir Crit Care Med 2001;163(1):12-8.
  13. 574. Robinson SM, Harrison BD, Lambert MA. Effect of a preprinted form on the management of acute asthma in an accident and emergency department. J Accid Emerg Med 1996;13(2):93-7.
  14. 575. Arnold DH, Gebretsadik T, Minton PA, Higgins S, Hartert TV. Clinical measures associated with FEV1 in persons with asthma requiring hospital admission. Am J Emerg Med 2007;25(4):425-9.
  15. 576. Shim CS, Williams MH Jr. Evaluation of the severity of asthma: patients versus physicians. Am J Med 1980;68(1):11-3.
  16. 577. Emerman CL, Cydulka RK. Effect of pulmonary function testing on the management of acute asthma. Arch Intern Med 1995;155(20):2225-8.
  17. 578. O'Driscoll BR, Howard LS, Davison AG, British Thoracic Society. BTS guideline for emergency oxygen use in adult patients. Thorax 2008;63(suppl. 6):vi1-68.
  18. 579. Carruthers D, Harrison BD. Arterial blood gas analysis or oxygen saturation in the assessment of acute asthma? Thorax 1995;50(2):186-8.
  19. 580. Pearson MG, Spence DP, Ryland I, Harrison BD. Value of pulsus paradoxus in assessing acute severe asthma. British Thoracic Society Standards of Care Committee. BMJ 1993;307(6905):659.