Circadian patterns of emergency asthma presentations: implications for staffing and treatment.

UNLABELLED

Are there circadian patterns for time of presentation and clinical status in asthmatic patients admitted to an emergency department for acute exacerbations?

DESIGN

Prospective observational study.

SETTING

Urban community teaching hospital emergency department.

PARTICIPANTS

279 consecutive patients who presented a total of 310 times with asthma exacerbations between October 19 and December 31, 1993. We grouped patients aged 16 years and above as adults and patients younger than 16 years of age as children. INFORMATION COLLECTED: Time of emergency department presentation, time attack began (for adult patients), peak expiratory flowrate prior to emergency department treatment (for adult patients), need for hospital admission, ventilatory failure during an acute attack, and death during an acute attack.

RESULTS

Circadian patterns were demonstrated for time of presentation. For the total study group, the peak time of presentation was 8:00 PM to 11:59 PM (p < 0.05) and the trough time of presentation was 4:00 AM to 7:59 AM (p < 0.01). There were differences in peak time of presentation for patients grouped by age. For adult patients only, the peak time of presentation was 8:00 AM to 11:59 AM (p < 0.01), whereas for children only, the peak time of presentation was 8:00 PM to 11:59 PM (p < 0.001). No statistically significant patterns in time of attack onset, hospital admission rates, or peak flow measurements were observed.

CONCLUSIONS

There are circadian patterns for the time at which patients with acute asthmatic exacerbations present to our emergency department. Adult patients have a peak time of presentation between 8:00 AM and 11:59 AM, whereas children have an apparent peak time of presentation between 8:00 PM and 11:59 PM. For all age groups, there is a trough in presentation between 4:00 AM and 7:59 AM.