THE 88-PARTS-PER-THOUSAND SATURATION TEST - A SIMPLE LUNG-FUNCTION TEST FOR YOUNG-CHILDREN

Objective. The 88% saturation test (88%-SAT) was developed as an alter native to standard spirometry for those young children unable to perfo rm standard forced expiratory maneuvers. In adults, this test revealed rapid desaturation in those persons with a history of asthma when com pared with healthy control subjects. Similar findings in children were tested. Setting. Tertiary care hospital. Patients. Thirty-three forme r premature infants (28.3 +/- 2.3 weeks gestation), aged 5 to 7 years, who were participating in a follow-up study, were enrolled in this st udy. Design. The study compared the 88%-SAT with standard spirometry a nd respiratory health characteristics ascertained through a parental q uestionnaire. The 88%-SAT consists of continuous measurement of hemogl obin saturation by pulse oximetry (Sao(2)) while the subject breathes a nonhumidified 12% oxygen and nitrogen mixture for 10 minutes or unti l Sao(2) decreases to 88%, whichever occurs first. Abnormal 88%-SAT wa s defined as a decrease of Sao(2) to 88% within the 10-minute period, and abnormal spirometry was defined using standardized values. Results . Of the 20 children who successfully completed both spirometry and th e 88%-SAT, 10 had normal spirometry results and did not desaturate to 88%, and 5 had abnormal spirometry and 88%-SAT results. Four children did not desaturate during the 88%-SAT, but had abnormal spirometry res ults, and one child had abnormal 88%-SAT results, but normal spirometr y. Ten additional children completed the 88%-SAT, but not standard spi rometry. Three children were unable to complete either test. Of those 30 children tested, 7 (23%) had a history ol: reactive airways disease , and all 7 had abnormal 88%-SAT results. The 88%-SAT had greater sens itivity (100% vs 75%) and specificity (87% vs 63%) than spirometry in identifying children with known reactive airways disease. The mean McC arthy general cognitive index (GCI) of the group performing both spiro metry and the 88%-SAT (n = 20) achieved a mean (+/- SD) GCI of 96.2 +/ - 16.7, and the group (n = 30) that completed the 88%-SAT had a mean ( +/- SD) GCI of 75.2 +/- 26.3 (chi(2) P <.012). The 10 children able to perform only the 88%-SAT had a mean GCI (+/- SD) of72.8 +/- 26.9, and the 3 children unable to perform either test had a mean GCI (+/- SD) of 63 +/- 11. Conclusions. Our data suggest that the 88%-SAT may be mo re effective than spirometry for identifying reactive airways disease in young, uncooperative, or developmentally delayed children. The dry air of the hypoxic inspired gas may function as an airway challenge, l eading to decreased oxygenation in patients with reactive airways.