Tracheal/chest auscultation for wheeze and transcutaneous oximetry have bot
h been suggested as measures of outcome in bronchial provocation tests in y
oung children. This study aimed to compare the sensitivity and safety of th
ese two techniques as end-points for methacholine challenge in children age
d <4 yrs.
Seventy-two methacholine challenges were performed in 39 children aged <4 y
rs with recurrent wheeze. Arterial oxygen saturation (Sa,O-2) and transcuta
neous oxygen pressure tcPO(2) continuously, and the test was terminated whe
n wheeze was heard or at Sa,O-2 <91%. tcPO(2) was not used as an end-point.
Wheeze or desaturation occurred at less than or equal to 8 mg.mL(-1) methac
holine in every test. One child had transient clinical cyanosis, but no oth
er ill-effects were seen. Fifty-six tests (78%) were terminated for wheeze,
seven (10%) for fall in Sa,O-2 and nine (12%) showed simultaneous response
s in both parameters. Twenty-eight tests (39%) contained a fall in tcPO(2)
>3 kPa but six of these also showed a significant rise. Fifty-three tests (
75%) contained a fall in tcPO(2) >15%, but 20 of these also showed a signif
icant rise.
Tracheal/chest auscultation with Sa,Oz monitoring is a sensitive and relati
vely safe end-point for bronchial challenges in preschool children, The err
atic pattern of transcutaneous oxygen pressure response in some children ca
sts doubt on its reliability as a proxy measure of bronchial obstruction.