This information in sourced from the Primary Care Respiratory Society, SIGN, NICE, NHS England and the Centre for Evidence-Based Medicine (CEBM):

Investigations

• Spirometry is frequently normal in patients with asthma (unless they are experiencing a current worsening of their asthma symptoms)
• Most pulmonary function tests have the potential to spread Covid‑19 including spirometry, FeNO and PEFR
• Only carry out pulmonary function tests for urgent cases and if the results will have a direct impact on patient care
• Spirometry and FeNO should be reserved for those patients with an intermediate probability of asthma (ideally through a primary care-based respiratory diagnostic service)
• If PEFR evaluation in clinic is considered necessary this can be carried out using the patients own PEF meter and disposable mouthpiece in a room with an open window or outside the building
• Guidance from the Association for Respiratory Technology and Physiology (ARTP) and the Primary Care Respiratory Society (PCRS) on 3 June – developed by an NHS England ‘task and finish group’ – said that GP practices should begin to restore spirometry ‘as a matter of urgency’ and a ‘priority’.

Structured clinical assessment

• Diagnosis of patients with suspected asthma can, in many cases, be made without the need for testing procedures
• A structured clinical assessment should include a detailed history, examination and review of the patient’s clinical records including the results of any previous PEFR, spirometry or blood eosinophils
• Patients with a high probability of asthma following a structured clinical assessment can be managed with a trial of treatment with peak flow monitoring at home
• It is important to ensure that the patient is well trained to undertake peak flow readings at home using maximal respiratory effort and in accurately recording the measurements
• This training can take place via video consultation
• Where peak flow monitoring is not possible use of a validated symptom questionnaire is recommended eg the Asthma Control Test (paper based version or weblink are freely available)

Criteria for a high probability of asthma include:

• Recurrent episodes of symptoms
• Wheeze confirmed by a health care professional
• A personal or family history of asthma
• A past record of variable airflow obstruction
• No features to suggest an alternate diagnosis
• Clear and repeated evidence of 20% variability of PEFR collected using a PEFR diary

See also:

Asthma – managing exacerbations