Peak Expiratory Flow Rate for Emergency Department Management of Acute Asthma Exacerbation

It is common practice to use peak-expiratory flow rate (PEFR) as an indicator of severity in patients that present with acute asthma exacerbation. There is, however, little data supporting this practice.

A recent Canadian 20 site prospective observational cohort study of 805 ED patients with acute asthma exacerbation concluded PEFR was not useful in predicting need for hospitalization or relapse following discharge.

As this was a cohort observational study, the conclusions that can be drawn are limited by the lack of randomization and control; it is necessary to conduct a randomized controlled trial to quantify how much time is expended caring for these patients, and gather safety data.

This is important because no studies have quantified differences in resource utilization based on PEFR-guided management compared to non-PEFR-guided management. It is possible physicians following PEFR-guided management use comparatively more resources, such as nebulizer treatments and hospitalization, in order to treat low PEFR values in patients they would have otherwise discharged based on clinical judgement alone. If outcomes are not affected by non-PEFR-guided management, it may reduce resource utilization to avoid using PEFR-guided management.

The investigators seek to determine if PEFR-based management and non-PEFR-based management perform similarly in guiding ED management of acute asthma exacerbations. Specifically, they seek to determine if the proportion of patients with no or mild asthma symptoms at 150 minutes after enrollment arrival is similar in the two groups.

At 150 minutes, it is expected that approximately 80% of patients will have no or mild asthma symptoms in both groups. When comparing the proportion of patients between the two groups, a confidence interval less than 20% wide (10% on either side of the point estimate) is desired. Therefore, goal enrollment is 110 patients per group.

This study will only include patients who are discharged from the ED. Patients who are enrolled and then eventually admitted to the hospital will be tabulated but excluded from the analysis.

Statistical analysis will compare the difference in the proportion of patients who achieve the primary outcome between groups, with the associated 95% confidence interval. Secondary outcomes will be presented descriptively; depending on the final distribution of the data, the investigators will present the means or medians of the data with the associated difference in mean/median with the associated 95% confidence intervals

Inclusion criteria

• Presumed diagnosis of asthma, requiring at least 2 nebulized albuterol treatments
• Presenting with acute asthma exacerbation defined as acute or subacute episodes of progressively worsening shortness of breath, cough, wheezing, and chest tightness, or some combination of these symptoms
• Start of enrollment process must occur within 15 minutes of being roomed in the ED
• Working phone number and willingness to be contacted at least 72 hours following encounter

Exclusion criteria

• Prisoner or in custody
• Pregnant
• Known diagnosis of COPD
• Co-morbid medical conditions that patient is seeking treatment for concurrently
• Non-English speaking
• Unable to provide informed consent
• In the resuscitation bay or on non-invasive positive pressure ventilation (NPPV)