{
  "abstract": "Introduction Asthma exacerbations are diagnosed and monitored using clinical features and forced airways manoeuvres which can be difficult for patients to perform. Tests assessing small airways function might provide more nuanced information about the exacerbation and response to treatment, and this systematic review (SR) evaluated the evidence to support these tests during adult asthma exacerbations.Methods The SR followed PRISMA guidelines and was registered with PROSPERO (CRD42024494994). MEDLINE, EMBASE, CENTRAL, and CINAHL with no time or language restrictions. Risk of bias was assessed using RoB 2.0 (RCTs) and the Newcastle-Ottawa Scale (observational studies). A narrative synthesis was conducted due to methodological heterogeneity.Results Seven studies (six observational, one RCT) involving 634 adults with asthma exacerbations met inclusion criteria. Five studies assessed Forced Expiratory Flow (FEF) at 25%–75% of the pulmonary volume, one reported FEF25/50/75, and one used multiple-breath washout (MBW). Most studies were exploratory and limited by small sample sizes, heterogeneous methodologies, and incomplete statistical reporting, including inconsistent use of group comparisons and varied follow-up durations. No study used small airway tests as a primary diagnostic tool, and statistical significance was inconsistently reported. Risk of bias was notable across all studies.All studies reported a good ability for patients to perform tests of small airways during exacerbations. All reported impaired small airway function during exacerbations with improvements at follow-up (taken 2 to 8 weeks after the initial presentation). Most reported a greater improvement in FEF25–75 than in FEV1 (Increments in FEF25–75 of 152%, 124%, and 99.7% and 80%, 62%, and 54% in FEV1). MBW indices were elevated during exacerbations and declined during recovery, with a strong inverse correlation between Sacin and FEV1 (ρ=–0.67, p=.006). One RCT (n=36) evaluated bronchodilator response with or without non-invasive ventilation, showing modest post-treatment changes in FEF25–75.Abstract M20 Figure 1Percentage change in FEF25–75 and FEV1 from pre- to post-treatment in three studies. Changes were calculated from reported group mean values unless otherwise specified. Units shown are percent predicted (% predicted)Conclusion Tests of small airway function are feasible during asthma exacerbations and may detect clinically relevant changes. It remains unclear which test may be optimal and whether tests of small airways function during exacerbation enhance early diagnosis or treatment monitoring.",
  "authors": [
    {
      "affiliations": [
        "University of Birmingham, Birmingham, UK"
      ],
      "name": "A Alshehri"
    },
    {
      "affiliations": [
        "University of Birmingham, Birmingham, UK"
      ],
      "name": "MI Alshahrani"
    },
    {
      "affiliations": [
        "University of Birmingham, Birmingham, UK"
      ],
      "name": "E Sapey"
    },
    {
      "affiliations": [
        "University of Birmingham, Birmingham, UK"
      ],
      "name": "RA Stockley"
    },
    {
      "affiliations": [
        "King Saud University, Riyadh, Saudi Arabia"
      ],
      "name": "M Almeshari"
    }
  ],
  "title": "M20 Can measures of small airway dysfunction aid with the diagnosis or management of asthma exacerbations? – A systematic review",
  "uid": "4e39175e-4edc-52e7-a6b4-35969551a456"
}