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Am J Emerg Med. 2010 Feb;28(2):221-3. doi: 10.1016/j.ajem.2008.10.031.

The utility of serial peak flow measurements in the acute asthmatic being treated in the ED.

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Department of Emergency Medicine, Keck/USC School of Medicine, Los Angeles, CA 90033, USA.



Peak flow is used extensively in emergency departments (EDs) to both assess asthma patient's status on arrival as well as to document clinical improvement during treatment. Many algorithms suggest serial peak expiratory flow (PEF) measurements during an ED stay.


The aim of the study was to assess the contribution of serial PEF in describing the overall improvement of asthmatics over the course of an ED visit for acute exacerbation of their asthma.


This was a prospective institutional review board-approved study of mild/moderate asthmatics presenting to an inner-city ED serving a large Latino population. Peak expiratory flow was measured before treatment (baseline PEF) and after each inhaled treatment (PEF post RX#1, PEF post RX#2, PEF post RX#3) while in the ED.


One hundred consecutive patients made up this study cohort. The change from baseline PEF to PEF #1 represented 86% (95% confidence interval [CI], 76%-96%) of the total improvement experienced by these patients with asthma. The change from PEF post RX#1 to PEF post RX#2 represented 7.5% (95% CI, -4.2% to 26%) of the total improvement and PEF post RX#2 to PEF post RX#3 represented 8.6% (95% CI, -1% to 34%) of the total PEF improvement seen.


No correlation between outcome and PEF% of predicted was made or implied.


The improvement in PEF seen after the first ED inhaled therapy appears to describe most of the total improvement seen in asthmatic patients. Subsequent PEFs provided little additional information.

[Indexed for MEDLINE]

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