A new method of estimating bronchial hyper-responsiveness in younger children.

By using the new device, the "Astograph," it is possible to measure the continuous changes of respiratory resistance (Rrs) during bronchial inhalation challenge. This method, however, is not suitable for younger children because of wide variations in Rrs. So we studied a technique using a transcutaneous oxygen pressure (tcPO2) monitoring system. The bronchial reactivity and sensitivity were significantly correlated between Rrs and tcPO2 (P less than .001), and there was no correlation between cardiac output and Rrs. The tcPO2-method is useful for measuring bronchial responsiveness, especially in younger children.