TRANSCUTANEOUS BLOOD-GAS ANALYSIS DURING SLEEP AND EXERCISE IN CYSTIC-FIBROSIS

Forty patients with cystic fibrosis (CF) (mean age, 13 ± 2.5 years) were studied with transcutaneous (tc) blood gas monitoring (TCM) during sleep and exercise. By comparing arterial blood samples and TCM in 24 of them (27 samples), a mean bias of tc O 2–15.91 mmHg with a precision of 8.4 mmHg was found. The mean bias of tc CO 2 was 7.21 mmHg with a precision of 3.9 mmHg. A standardized submaximal exercise test (1.7 W/kg) was performed in all 40 CF patients and in 14 healthy control subjects (mean age, 13 ± 0.5 years). The typical tc trend during exercise for CF and healthy subjects was a slight increase of tc O 2 levels and tc CO 2 stability. A minor decrease of tc CO 2 values occurred in four CF patients (no greater than 7 mmHg). In 28 patients (mean age, 13 ± 3 years), tc O 2 and tc CO 2 were recorded during sleep. In 13 of them, apparent hypoxemic episodes were noted, without relation to the degree of airway obstruction. There were simultaneous episodes of hypercapnia in ten patients. Some difficulties were encountered in analyzing long‐term recordings. Tc O 2 drifts upward and tc CO 2 decreases during the recordings over several hours. The change in electrode position after 4 h of sleep modified tc O 2 and tc CO 2 values. Such difficulties limit the usefulness of long‐term but not short‐term recordings. Pediatr Pulmonol 1990; 8:162‐167. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company