Asthma Management Handbook

Completing secondary assessments and reassessing severity

Recommendations

When practical after starting treatment, complete clinical assessments and reassess severity.

Table. Secondary severity assessment of acute asthma in adults and children 6 years and over Opens in a new window Please view and print this figure separately: https://www.asthmahandbook.org.au/table/show/63

Table. Secondary severity assessment of acute asthma in children 0–5 years Opens in a new window Please view and print this figure separately: https://www.asthmahandbook.org.au/table/show/64

Table. Initial bronchodilator treatment in acute asthma (adults and children 6 years and over)

  • Do not use IV short-acting beta2 agonists routinely for initial bronchodilator treatment.

  • Do not give oral salbutamol.

  • Monitor for salbutamol toxicity (e.g. tachycardia, tachypnoea, metabolic acidosis, hypokalaemia) – may occur with inhaled or IV salbutamol.

Mild/Moderate

Severe

Life-threatening

Give salbutamol 4-12 puffs (100 mcg/actuation) via pMDI and spacer

Repeat every 20-30 minutes for the first hour if required (sooner, if needed to relieve breathlessness)

Give salbutamol 12 puffs (100 mcg/actuation) via pMDI and spacer

If patient unable to breathe through a spacer, give 5 mg nebule via nebuliser

Start oxygen therapy if oxygen saturation <95% and titrate to target:

Adults: 92–95%
Children: 95% or higher

Repeat salbutamol as needed. Give at least every 20 minutes for first hour (3 doses)

Give salbutamol 2 x 5 mg nebules via continuous nebulisation driven by oxygen

Maintain oxygen saturations:

Adults: 92% or higher
Children: 95% or higher

Arrange immediate transfer to higher-level care

When dyspnoea improves, consider changing to salbutamol via pMDI plus spacer or intermittent nebuliser (doses as for severe acute asthma)

† Give one puff at a time followed by 4 breaths (See Table. Using pressurised metered-dose inhalers in acute asthma)

‡ See Table. Using nebulisers in acute asthma

Note: To deliver nebulised bronchodilators in a patient receiving oxygen therapy, use an air-driven compressor nebuliser and administer oxygen by nasal cannulae.

Asset ID: 80

Close

Table. Initial bronchodilator treatment in acute asthma (children 0–5 years)

  • Do not use IV short-acting beta2 agonists routinely for initial bronchodilator treatment.

  • Do not give oral salbutamol.

  • Monitor for salbutamol toxicity (e.g. tachycardia, tachypnoea, metabolic acidosis, hypokalaemia) – may occur with inhaled or IV salbutamol.

  • Closely monitor level of consciousness, fatigue, oxygen saturation, respiratory rate and heart rate. If symptoms do not respond, contact a paediatrician or senior clinician and reconsider the diagnosis. 

  • In children under 12 months old, asthma is less likely to be the cause of wheezing than other conditions (e.g. bronchiolitis, pneumonia).

Mild/Moderate

Severe

Life-threatening

Give salbutamol 2-6 puffs (100 mcg/actuation) via pMDI and spacer plus mask

Repeat every 20-30 minutes for the first hour if needed (sooner, if needed to relieve breathlessness)

Give salbutamol 6 puffs (100 mcg/actuation) via pMDI and spacer plus mask

If patient unable to breathe through a spacer, give 2.5 mg nebule via nebuliser

Start supplementary oxygen if oxygen saturation <95%

Titrate to 95% or higher

Repeat salbutamol as needed. Give at least every 20 minutes for first hour (3 doses)

Give salbutamol 2 x 2.5 mg nebules via continuous nebulisation driven by oxygen

Maintain  oxygen saturation at 95% or higher

Arrange immediate transfer to higher-level care

When dyspnoea improves, consider changing to salbutamol via pMDI plus spacer or intermittent nebuliser (doses as for severe acute asthma)

† Give one puff at a time followed by 4 breaths (See Table. Using pressurised metered-dose inhalers in acute asthma)

‡ See Table. Using nebulisers in acute asthma

Asset ID: 81

Close
How this recommendation was developed

Consensus

Based on clinical experience and expert opinion (informed by evidence, where available).

Complete a brief history, including:

  • reliever taken for this episode (dose, number of doses, time of last dose)
  • current asthma medicines (regular and as-needed, including type of devices used)
  • what triggered this episode, if known (e.g. allergies, immediate hypersensitivity, medicines, respiratory infections. Note: acute asthma is rarely triggered by food allergies.)
  • coexisting heart or lung disease, including chronic obstructive pulmonary disease.
How this recommendation was developed

Consensus

Based on clinical experience and expert opinion (informed by evidence, where available).

For adults and children, start titrated oxygen therapy for all patients with severe or life-threatening acute asthma. Maintain oxygen saturation of 92–95% for adults and at least 95% for children.

  • Excessive oxygen administration can lead to hypercapnoea in people with asthma and COPD
How this recommendation was developed

Adapted from existing guidance

Based on reliable clinical practice guideline(s) or position statement(s):

  • British Thoracic Society and Scottish Intercollegiate Guidelines Network, 20081
  • Global Initiative for Asthma, 20122
  • Abramson et al. 20123
  • O'Driscoll et al. 20084

Arrange chest X-ray if pneumonia, atelectasis, pneumothorax or pneumomediastinum is suspected.

How this recommendation was developed

Consensus

Based on clinical experience and expert opinion (informed by evidence, where available).

More information

Assessment of oxygen status in acute asthma

Hypoxia is the main cause of death that is due to acute asthma.5

Routine objective assessment of oxygen saturation at initial assessment of acute asthma is needed because clinical signs may not correlate with hypoxaemia.

Pulse oximetry is the internationally accepted method for routine assessment of oxygen status in patients with acute asthma.2

The risk of hypercapnoea increases when oxygen saturation falls below 92%.6

Pulse oximetry does not detect hypercapnoea, so blood gas analysis is necessary if hypercapnoea is suspected in patients with severe or life-threatening acute asthma.

Close
Oxygen therapy in acute asthma

Oxygen is a treatment for hypoxaemia, not breathlessness. Oxygen has not been shown to improve the sensation of breathlessness in non-hypoxaemic patients.4 When oxygen supplementation is used, pulse oximetry is necessary to monitor oxygen status and titrate to target.

The aim of titrated oxygen therapy in acute care is to achieve normal or near-normal oxygen saturation, except in patients who are at risk of hypercapnoeic respiratory failure,4 such as patients with overlapping asthma and COPD.

Adults

In adults with acute asthma, titrated oxygen therapy using pulse oximetry to maintain oxygen saturation at 93–95% while avoiding hyperoxaemia achieves better physiological outcomes than 100% oxygen at high flow rate (8 L/min).7 High-concentration and high-flow oxygen therapy cause a clinically significant increase in blood CO2 concentration in adults with acute asthma.78

National guidelines for the management of acute exacerbations of COPD recommend that hypoxic patients should be given controlled oxygen therapy via nasal prongs at 0.5–2.0 L/minute or a venturi mask at 24% or 28%, with target oxygen saturation of over 90% (PaO2 >50 mmHg, or 6.7 kPa).3 Excessive oxygen administration should be avoided because it can worsen hypercapnoea.3

Children

Drying of the upper airway is a potential complication of oxygen therapy in children,910 which might contribute to bronchoconstriction.10 Humidified oxygen can be considered if necessary. Humidification is usually not needed for low flow oxygen (<4 L/minute in children or 2 L/minute in infants) for short term. Humidification may be considered if the oxygen is required for longer than 48 hours or if the nasal passages are becoming uncomfortable or dry.9

Guidance on oxygen delivery techniques and practical issues is available from  Sydney Children's Hospital Network and The Royal Children's Hospital Melbourne.

Close
Spirometry in acute asthma

Utility

Assessment of response to treatment should include spirometry considered alongside clinical assessment. Clinical assessment alone may underestimate the severity of airflow limitation.11

On its own, FEV1 (measured by spirometry) at 1 hour after admission to the emergency department does not closely correlate with the need for hospital admission in adults with acute asthma as assessed clinically.11

Feasibility and technique

Most adults with acute asthma can perform spirometry within the first hour of admission to the emergency department.12 (Hospital staff and primary care health professionals may need specific training in spirometry technique to be able to obtain acceptable spirometry in patients with acute asthma.12)

Younger children (most children under 6 years) are unlikely to be able to perform spirometry.

It may not be feasible to apply standard spirometry technique and manoeuvre acceptability criteria in patients with acute asthma:12

  • 80% of patients older than 12 years with acute asthma can perform an FEV1 manoeuvre. A forced exhalation from total lung capacity for 2 seconds is sufficient and provides useful information about the severity of airflow obstruction12
  • two attempts may suffice if patients are unable to make three attempts12
  • variability between manoeuvres of < 10% should be considered acceptable12
  • patients may not be able to tolerate nose clips12
  • patients are unlikely to be able to exhale for long enough to demonstrate the time-volume plateau. Although patients should aim for forced exhalation of at least 6 seconds, 2 seconds is acceptable for measuring FEV1 in clinical assessment during acute asthma.12 A spirometry manoeuvre might be considered acceptable if back-extrapolated volume is either < 5% of FVC or 0.15 L (whichever is greater), or a time to peak flow < 120 ms.12

Table. Tips for performing spirometry in patients with acute asthma

  • Ask the patient to sit straight upright, either in a chair or on a stretcher with their legs over the side.
  • Make sure the person forms a tight seal around the mouthpiece.
  • Tell the patient to take as deep a breath as possible, then blast out air as fast and hard as they can, then keep blowing until asked to stop. Aim for exhalation of maximal force for at least 2 seconds (6 seconds if FVC is measured).
  • You may need to give the patient lots of coaching, repeat instructions, and give immediate feedback on technique.

Asset ID: 66

Close
Close
Peak expiratory flow in acute asthma

Peak expiratory flow rate obtained using a peak flow meter underestimates the severity of airflow limitation in patients with acute asthma, compared with FEV1 obtained by spirometry.13

Peak expiratory flow is not a sensitive measure of small clinical improvements as perceived by the patient.14

Close

References

  1. British Thoracic Society (BTS) Scottish Intercollegiate Guidelines Network (SIGN). British Guideline on the Management of Asthma. Quick Reference Guide. Revised May 2011. BTS, SIGN, Edinburgh, 2008.
  2. Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. GINA, 2012. Available from: http://www.ginasthma.org
  3. Abramson MJ, Crockett AJ, Dabscheck E, et al. The COPD-X Plan: Australian and New Zealand guidelines for the management of chronic obstructive pulmonary disease. Version 2.34. The Australian Lung Foundation and The Thoracic Society of Australia and New Zealand, 2012. Available from: http://www.copdx.org.au/
  4. O’Driscoll BR, Howard LS, Davison AG, British Thoracic Society (BTS) Emergency Oxygen Guideline Development Group. BTS guideline for emergency oxygen use in adult patients. Thorax. 2008; 63 (Suppl 6): vi1-vi68. Available from: http://thorax.bmj.com/content/63/Suppl_6/vi1.full
  5. Hodder R, Lougheed MD, Rowe BH, et al. Management of acute asthma in adults in the emergency department: nonventilatory management. CMAJ. 2010; 182: E55-67. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2817338/
  6. British Thoracic Society (BTS), Scottish Intercollegiate Guidelines Network (SIGN). British Guideline on the Management of Asthma. A national clinical guideline. BTS, SIGN, Edinburgh, 2012. Available from: https://www.brit-thoracic.org.uk/guidelines-and-quality-standards/asthma-guideline/
  7. Perrin K, Wijesinghe M, Healy B, et al. Randomised controlled trial of high concentration versus titrated oxygen therapy in severe exacerbations of asthma. Thorax. 2011; 66: 937-41. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21597111
  8. Rodrigo GJ, Rodriquez Verde M, Peregalli V, Rodrigo C. Effects of short-term 28% and 100% oxygen on PaCO2 and peak expiratory flow rate in acute asthma: a randomized trial. Chest. 2003; 124: 1312-7. Available from: http://journal.publications.chestnet.org/article.aspx?articleid=1081910
  9. Sydney Children's Hospital. Oxygen therapy and delivery devices – SCH. Practice guideline. Guideline No: 0/C/13:7019-01:00. Sydney Children's Hospital Westmead, Sydney, 2013. Available from: http://www.chw.edu.au/about/policies/alphabetical.htm
  10. The Royal Children's Hospital of Melbourne, Oxygen Delivery. Clinical Guidelines (Nursing), The Royal Children's Hospital 2013. Available from: http://www.rch.org.au/rchcpg/hospitalclinicalguidelineindex/Oxygendelivery/
  11. Wilson MM, Irwin RS, Connolly AE, et al. A prospective evaluation of the 1-hour decision point for admission versus discharge in acute asthma. J Intensive Care Med. 2003; 18: 275-285. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15035763
  12. Silverman RA, Flaster E, Enright PL, Simonson SG. FEV1 performance among patients with acute asthma: results from a multicenter clinical trial. Chest. 2007; 131: 164-171. Available from: http://journal.publications.chestnet.org/article.aspx?articleid=1084897
  13. Choi IS, Koh YI, Lim H. Peak expiratory flow rate underestimates severity of airflow obstruction in acute asthma. Korean J Intern Med. 2002; 17: 174-179. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12298428
  14. Karras DJ, Sammon ME, Terregino CA, et al. Clinically meaningful changes in quantitative measures of asthma severity. Acad Emerg Med. 2000; 7: 327-334. Available from: http://onlinelibrary.wiley.com/doi/10.1111/j.1553-2712.2000.tb02231.x/abstract