1. Introduction To discharge a preterm newborn after staying in neonatal intensive care unit (NICU) is a multifactorial decision. According to the American Academy of pediatrics guidelines of the physiologic competencies for hospital discharge of the high-risk neonate including preterm ones, are sufficient oral feeding and mature respiratory control, and finally the ability to maintain a normal body temperature in an unheated open bed (1). These mostly are achieved between 36 and 37 weeks' postmenstrual age (2-4).
Shortening the period of a hospital stay, it could be beneficial to decrease the emotional stress resulted from the separation between the mother and the newborn and parents; furthermore, it may reduce the hospital-acquired co-morbidities as sepsis and surgical needs (5) and accordingly reduce the economic burden on the society.
The timing to wean from the incubator is crucial since the immaturity of preterm newborn's thermoregulatory mechanisms which could affect weight gain as an attempt to maintain body temperature, achieving full feeding volume, and as a result could delay discharge from hospital (6, 7). The target weight for incubator weaning varies widely among NICUs. The common usual practice is between of 1700-1800 g, and it is generally based on the professional experience and judgment (8, 9).
In 2010, a Cochrane Review assessed transferring preterm infants from incubator to open bed at a lower body weight (˂1700 g) by comparing to a higher body weight (˃ 1700 g). The review showed that preterm newborns can be transferred to open beds at 1600 g without adverse effects on temperature stability in terms of return to incubator or daily weight gain (10). A multicenter trial achieved the same result (11).
Moreover, there are few studies showed that infants can be successfully transferred into cots at weights down to 1500 g (9, 12). A pilot study carried out stepwise four cohort trials of newborn's transfer from incubators to open beds at 1800 g, then at 1700 g, then at 1600 g and then finally at 1500 g (13). It demonstrated that there were no significant differences between the four cohorts in maintain body temperature after incubator weaning.
The primary outcome of this study was to evaluate the feasibility and safety of incubator weaning for medically stable preterm neonates to unheated open cot at a body weight of 1400 g in terms of daily weight gain and temperature control. Newborns in the same study period were compared to a control group weaned at body weight of 1600 g.
2. Subjects and Methods:
2.1. Study design A prospective randomized clinical trial was conducted at NICU at King Fahad Medical City, Riyadh, Saudi Arabia. Preterm newborns admitted to NICU fulfilling items in inclusion and exclusion criteria during the period from August 2017 to October 2018 were included into the study.
All eligible newborns were randomized into two groups to be weaned at 1,400 or at 1,600 g in a 1:1 ratio, using random block of 4. Newborns were eligible if body weight less than 1400 g, they were at least 5 days of age at the time of transferring to cot, they fed at least 60 ml/kg/day at the time of transferring to cot, and they are medically stable with no significant apnea or bradycardia, no ventilator support, no phototherapy and not having a major congenital abnormality. Newborns were excluded if they didn't fulfill the above criteria or unlikely to reach the target weight within 7 days.
2.2. Procedures Nursery temperatures were adjusted at 24-28 ◦c from birth to cot. The subjects were dressed in a hat, one vest and two wraps. Then, they were randomly assigned to either study group or control group. Infants were weighed naked daily. In the study group, the newborns were transferred to cot at a weight of 1400 to 1499 g and in the control group; they were transferred at a weight of 1600 to 1699 g. In the first day in the open cot, they were not bathed.
2.3. Data Collected
* Baseline characteristics as birth weight, gestational age (GA), gender, age in days in the transfer day, body weight and GA in the transfer day.
* Relevant data from to incubator weaning
* After transfer, hourly axillary temperatures were taken until two consecutive readings between 36.4 and 37.1 °C. Then, temperatures were taken every 3 hours with each feed for at least 72 hours. After that, temperatures were taken four times a day minimum until discharge. If the axillary temperature was ˂36.4°C, thus an additional wrap was added. If the temperature was still low for an hour later, then the infant was returned to the incubator. Meanwhile, if the temperature was more than 37.1°C, a wrap was reduced.
* No of infants who failed to be transferred to cot. Failure of transfer is defined as the inability to maintained body temperatures above 36.4°C in a two consecutive axillary temperatures in a cot despite of adding covering.
* For infants who remained in an open crib, the rate of weight gain calculated every day over the week before and after transfer. In the discharge day, age in days after transfer to discharge date, WT and GA.
2.4. Statistical methodology: Data were statistically described in terms of mean ± SD for continuous data and in frequencies (number of cases). For comparative purposes between groups in all continuous data, independent t-test or Mann Whitney t test was adopted. X2-square and fisher test were used for assessing association in categorical data.. P values less than 0.05 were considered statistically significant. All statistical calculations were done using computer program IBM SPSS (Statistical Package for the Social Science; IBM Corp, Armonk, NY, USA) release 21 for Microsoft Windows.
2.5. Ethical considerations: Due to safety concerns, the study was carried out in two steps. Initially, we started infants' weaning with the approved weaning weight at1500 grams. A total of 19 preterm infants were randomized in two groups. Both groups were weaned to cot with a 100% success rate without any complications. Afterwards, the study was approved by the local Ethics Committee to start the second phase of the study at weaning weight of 1400 g. The parents were all directly contacted and agreed in writing informed consent.
