O058 Are short central apnoeas in preterm infants really benign? Effects on cardiovascular control.

INTRODUCTION: Preterm infants frequently experience respiratory instability in the form of short apnoeas and periodic breathing. Animal studies have shown that repetitive hypoxia associated with periodic breathing can alter autonomic control. We aimed to elucidate if apnoea and periodic breathing were associated with autonomic cardiovascular control, thus exacerbating the consequences of respiratory disturbance longitudinally over the first 6 months after hospital discharge. METHODS: Preterm infants born between 28-32 weeks gestational age (GA) were studied during supine daytime sleep at 32-36 weeks post menstrual age (PMA) (n=29), 36-40 weeks PMA (n=27), 3-months corrected age (CA) (n=20) and 6-months CA (n=26). The percentage total sleep time (%TST) spent having central apnoeas at each study was calculated. Autonomic control was assessed using heart rate variability in ranges of total power, low frequency (LF, reflecting sympathetic + parasympathetic activity) and high frequency (HF, parasympathetic activity), and LF/HF ratio (sympathovagal balance). RESULTS: The amount of time spent with short central apnoeas decreased with increasing postnatal age in both active sleep (AS) and quiet sleep (QS). In both sleep states, total, LF and HF power increased with postnatal age, while LF/HF decreased in AS. In both AS and QS %TST spent with short central apnoeas was negatively correlated with Total, LF and HF power (p<0.001 for all) and positively correlated with LF/HF (p<0.05). CONCLUSION: This study provides new evidence that short apnoeas, particularly periodic breathing, which is currently not detected or treated in the neonatal unit can affect autonomic cardiovascular control.