Background and purpose: Body position can play an important role in an infant's recovery from respiratory disease, but few studies have accounted for sleep state which is known to have a direct influence on the control of respiratory muscles as well as on metabolic and circulatory changes. The purpose of this study was to examine the influence of body position on respiratory function in pre-term infants whilst accounting for sleep state.
Method: Thoraco-abdominal motion was assessed using respiratory inductance plethysmography (RIP) to provide measures of relative rib cage (RC) and abdominal (AB) movement in ten non-ventilated pre-term infants. Continuous measurements of oxygen saturation (SaO2), pulse and heart rate (HR), were made and sleep state was recorded using behavioural criteria and electro-oculogram (EOG) measurements.
Results: The results showed a significant increase in HR in supine, but no significant difference in SaO2 as a function of position, compared to the prone position where a significant reduction was found in thoraco-abdominal asynchrony for both groups and a reduction in variability in both HR and SaO2. Intra-subject variability of thoraco-abdominal motion as a function of position demonstrated no significant difference on return to supine or on return to prone, illustrating good repeatability of measures.
Conclusions: Prone positioning of pre-term infants recovering from respiratory disease may improve respiratory function. As measured, the improvement in respiratory synchrony in prone position brings pre-term infants' breathing pattern into line with that expected in term infants.