[Relationship between PEF and SpO2 on acute asthma attack in children].

We evaluated the relationship between PEF and SpO2 on 126 acute asthma attacks of 52 asthmatic children (25 males, 27 females, age 6-17 yrs-old) whose PEF and SpO2 being measured either before or after inhalation of beta-agonist at out-patient clinic. In the whole age group over 6 yrs-old, values of %PEF were proportional to individual SpO2 (n = 76, R = 0.472, p < 0.001). However, the relationship between %PEF and SpO2 in the present study was different from that of the guideline proposed by WHO (Global Initiative for asthma, GINA), showing that the value of SpO2 corresponding to %PEF was higher in the present study than in GINA. Regarding the difference in age group, significant relationship between %PEF and SpO2 was observed in both lower (6-9 yrs-old) and middle age group (10-12 yrs-old) but not in older age group (over 12 yrs-old). Also, there was a significant relationship between %PEF and SpO2 in cases whose pulmonary function during stable condition showed no-obstructive change (FEV1.0% > 80%), but not in cases with obstructive change. On the other hand, averaged values of %PEF, SpO2, heart rate (HR), respiratory rate (RR) before inhalation of beta-agonist at out-patient clinic in cases with or without admission were 32.3% vs 50.0%, 93.0%, vs 95.0%, 115 bpm vs 100 bpm, and 27/min vs 25/min respectively, those difference being statistically significant. Although measurement of SpO2 is thought to be a useful index for assessing severity of childhood asthma exacerbation, clinician should recognize that value of SpO2 could be greater than 91% even though % predicted PEF is less than 60%. Especially in older age group, obstructive change during stable condition may disturb the relation of SpO2 to %PEF. In such cases, not only SpO2 but also PEF, which is objective index of airway obstruction, should be taken into account for assessing severity of exacerbation.