Effects of prone and supine positions on sleep state and stress responses in mechanically ventilated preterm infants during the first postnatal week

Background/rationale. Preterm infants in mechanical ventilation are vulnerable and may manifest physiological instability and a disorganized behavioural state when responding to external stimuli. Adequate positioning strategies may play an important role in protecting infants from environmental stressor and assisting quality of sleep. However, no study has examined effects of prone and supine positions on behavioural state and stress signs including startle, tremor, and twitch responses for ventilated preterm infants during the critical first week postbirth.</x> Aim of the study. The purpose of this study was to compare effects of prone and supine positions on behavioural state and stress responses in mechanically ventilated preterm infants. Design/methods. The infants were aged 25-36 weeks of gestation, less than or equal to 7 days of age, and without sedation or congenital abnormalities. Using a crossover design, 28 infants were randomly assigned to supine/prone or prone/supine position sequence. Infants were placed in each position for 2 hours. A stabilization period of 10 minutes before observation of each position was allowed. During the protocol, care procedures were kept minimal and ventilator settings remained unchanged. Behavioural state and frequencies of stress signs including startle, tremor, and twitch were systemically recorded and analysed with repeated measures analysis of variance. Findings. Infants when prone compared with supine had (a) less crying, less active sleep, and more quiet sleep states, and (b) fewer stress responses of startle, tremor, and twitch. Conclusion. Results indicate that prone positioning improves the quality of sleep and decreases stress for ventilated preterm infants during the first week postbirth. These may conserve energy and assist infants' extrauterine adaptation.