TRANSCUTANEOUS AND ARTERIAL BLOOD-GAS MONITORING DURING ACUTE ASTHMATIC SYMPTOMS IN OLDER CHILDREN

The relationship between transcutaneous and arterial blood gases was investigated in 14 children with asthmatic symptoms, aged 7-15 years, before and after the inhalation of salbutamol. The degree of bronchial obstruction was assessed by forced expiratory volume in one second (FEV,) and maximum expiratory flow when 25% of FVC remained to be expelled (MEF25). On average the transcutaneous P(O2) (tcP(O2)) was 1.3 kPa (range, 2.6-0 kPa) lower and the transcutaneous P(CO2) was 0.6 kPa (range, 0-1.5 kPa) higher than the corresponding arterial values (P < 0.01). The difference between arterial and transcutaneous P(O2) was the same over the whole range of values studied (7.5-14 kPa). After the inhalation of salbutamol, the relationship between transcutaneous and arterial blood gases was not significantly changed. Changes in transcutaneous P(O2) correlated to changes in MEF25 (P < 0.05), indicating a common denominator, probably the conditions in the peripheral airways. We conclude that the close relationship between transcutaneous and arterial blood gases, even after the inhalation of a beta-2 agonist, indicates that the transcutaneous technique can be used for monitoring acute bronchial obstruction and for evaluating the effects of treatment in children of different ages.