Objective: To (a) explore the contribution of infant, environmental, and historical factors to the number of days from initiation to achievement of full nipple feeding (transition time) for premature infants with a history of lung disease; (b) examine differences in the contribution of infant and environmental factors to transition time made by historical era, either earlier (in the 1980s) or later (in the 1990s); and (c) compare, within eras, the contribution to transition time of infant and environmental factors for infants with each lung diagnosis, respiratory distress syndrome (RDS) without bronchopulmonary dysplasia (BPD) or BPD.
Design: Data were collected at two midwestern hospitals from the records of premature infants with a diagnosis of either RDS without BPD or BPD. The influence on transition time of infant, environmental and historical factors was assessed with the Cox proportional hazards model. This analytic model, a form of regression analysis, also was used to explore how era influenced the contribution to transition time of infant and environmental factors. Finally, the contribution to transition time of infant and environmental factors was examined within diagnostic group for each era.
Sample: The hospital records audited were for infants who were 32 weeks gestational age or less with weight appropriate for gestational age. The number in each diagnostic group for each era was (a) BPD--Early, n = 35; (b) RDS--Early, n = 21; (c) BPD--Late, n = 21; and (d) RDS--Late, n = 15).
Results: All three types of factors (infant, environmental, and historical) contributed significantly (p < .05) to shortening or lengthening transition time. A diagnosis of BPD lengthened transition time only in the early era. Across both eras, the number of days on tube feedings significantly lengthened transition time, and the older the infant in postconceptional age (PCA) at initiation of nipple feeding, the shorter the transition time.
Conclusion: The contribution of infant, environmental, and historical factors to transition time confirmed the basic structure of the theoretical model of transition time for premature infants with a history of lung disease. The influence of era on the contributions to transition time of infant and environmental factors suggests that care policy and practice have shortened the transition time. Although the current findings support the basic structure of the theoretical model for infants with either RDS or BPD, the marginally significant (p < .10) shortening effect of PCA on transition time for infants with BPD in both eras suggests that advancement to full nipple feeding may be limited by neurodevelopmental capacities, including respiratory control. How these capacities can be supported for advancement to full nipple feeding is a challenge for nursing practice and research.