Concurrent validity of a new instrument for measuring nutritive sucking in preterm infants.

The purpose of this study was to examine the concurrent validity of the Whitney strain gage for the measurement of nutritive sucking in preterm infants. Ten preterm infants were studied continuously during at least one entire bottle feeding per week, from admission into the study until discharge from the nursery. Sucking was measured simultaneously by an adapted nipple and the Whitney gage. The two instruments were compared on the following measures: number of sucking bursts, number of sucks per burst, and duration of bursts and pauses between bursts. Total percent agreement for the occurrence of a sucking burst was 99.3% (K = .99). Sucks per burst varied from 2 to 113, with 89.3% of the pairs of sucking bursts differing by < or = 1 suck per burst. The mean absolute difference between the two instruments for the duration of sucking bursts and pauses was .64 s and .72 s, respectively. These results demonstrate the concurrent validity of the Whitney gage for measurement of sucking events in preterm infants.