Effect of Conservative Weaning of Thermoregulatory Support on Weight Gain and Length of Stay in Preterm Neonates

General Background:

There are three key milestones premature infants must meet prior to discharge from the NICU:

1. The ability to maintain their temperature in an open crib
2. The ability to consume enough calories for adequate growth by oral feeds
3. A demonstrated weight gain consuming these feeds.

It is well understood that infants must increase their resting metabolic rate when weaned from the isolette to an open crib (1, 6). Preterm neonates have less metabolic reserve (brown fat) to allow them to mount an appropriate thermogenic response to cold stress (4). The reserve they do have is often depleted at delivery, leaving them with little or no reserve (4). When a neonate is challenged to maintain its body temperature, it must increase heat production which may affect weight gain (3). Some institutions wean without regard to neonate's weight or feeding status, while others only begin the weaning process at a predetermined weight. Currently neonates are weaned from their isolettes based largely on the traditions and experiences of clinicians, without regard to their feeding status. However, there is currently very little evidence in the literature to inform practice on the ideal conditions for weaning a neonate from their isolette. An extensive literature review has revealed no published data regarding the relationship of feed status to success at isolette weaning.

The transfer to open crib is important; if the neonate is not able to maintain his/her temperature, the length of stay could be lengthened and weight gain adversely affected (3). Cold stress can also cause adverse clinical effects including lethargy, hypotonia, poor feeding, abdominal distention, vomiting, pallor, tachypnea, and respiratory distress (2). These adverse clinical effects may also lengthen cost and length of stay, as well as adversely affect feeding. Furthermore, a return to the isolette can be quite stressful to parents and family members (3).