Asthma: acute exacerbation: PEFR was comparable to FEV1.

Clinical bottom line (level 4)

  1. PEFR correlated reasonably well with FEV1 in patients with acute asthma.
Nowak et al: Annals of Emergency Medicine 1982; 11: 64-69
Expires November 2002

The study

Setting: emergency department, university hospital, USA

90 patients (aged mean 25 years, 62% female) with 109 episodes of acute asthma (acute bronchospasm and acute respiratory distress)

Excluded if
  • <16 or >40 years old
  • other cardiac or respiratory disease


    • All patients had terbutaline 0.25 mg s/c and iv aminophylline 5.6 mg/kg loading dose, followed by 0.9 mg/kg/hour.
    Independent unblinded reference standard, applied in all patients from a ?consecutive appropriate spectrum.
    Reference standard:
    • FEV1
    Diagnostic test: peak expiratory flow rate
    • ?100% followed for 48 hours

    The evidence

    pre-test probability of PEFR >75% predicted: 19%, (95% CI: 12% to 27%)
    pre-test probability of PEFR 50-75% predicted: 28%, (95% CI: 19% to 36%)
    pre-test probability of PEFR 25-50% predicted: 39%, (95% CI: 30% to 49%)
    pre-test probability of PEFR <25% predicted: 13%, (95% CI: 6.6% to 19%)

    diagnostic test FEV1 75% or more FEV1 <75% LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    PEFR 75% or more 18 13 5.8
    (3.4 to 9.9)     		58% 0.17
    (0.06 to 0.48)     		4%
    total 21 88


    diagnostic test FEV1 50-75% FEV1 <50%, >75% LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    PEFR 50-75% 21 22 2.5
    (1.6 to 3.9)     		49% 0.42
    (0.24 to 0.73)     		14%
    total 30 79


    diagnostic test FEV1 25-50% FEV1 <25%, >50% LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    PEFR 25-50% 22 6 5.6
    (2.5 to 13)     		79% 0.54
    (0.39 to 0.74)     		26%
    total 43 66


    diagnostic test FEV1 <25% FEV1 25% or more LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    PEFR <25% 7 3 16
    (4.6 to 54)     		70% 0.52
    (0.31 to 0.87)     		7%
    total 14 95

    • Correlation coefficient between PEFR and FEV1 = 0.8416 (p < 0.01).

    Comments

    1. Peak expiratory flow meters are cheaper, easier to use and more portable than spirometers.

    Citation

    1. Nowak RM, Pensler MI, Sarkar DD, et al: comparison of peak expiratory flow and FEV1 admission criteria for acute bronchial asthma. Annals of Emergency Medicine 1982; 11: 64-69
    Search Terms: reference from acute asthma chapter; Lee, Hsu, Stasior; Quick consult manual to evidence-based medicine: publ. Lippincott-Raven, 1997
    Contributor: Chris Ball and Clare Wotton, November 2000
    Reviewer: Mitsuhiro Kamei

    Clinical Question.
    Patient acute asthma
    Intervention or Exposure PEFR
    Comparison FEV1
    Outcome diagnosis.