EFFECT OF SLEEP STATE ON CEREBRAL HAEMOGLOBIN (Hb) VOLUME IN TERM NEWBORN INFANTS ASSESSED BY NEAR INFRARED SPECTROSCOPY (NIRS)

Abstract

NIRS can be used for monitoring cerebral haemodynamics and oxygenation in newborn infants. The AIM of this study was to assess the difference in cerebral Hb volume (Hb-tot = Hb-ox + Hb-red) between quiet and active sleep and to observe Hb during sleep state transitions. METHOD: NIRS (Wyatt. Lancet 1986;2:1063) was performed on 20 healthy term infants (birthweight: 2570 to 4150g, age: 2 to 8 days); TcpCO2, tcpO2, SO2 and heart rate were recorded and sleep states assessed according to Prechtl (Brain Res 76, p 185, 1974).RESULTS (values are median (range) umol/l): After transition from quiet to active sleep Hb-ox decreased: -3.0 (+5 -10) p>0.001 and Hb-tot: -4 (+5 -10) p<0.002. From active to quiet sleep Hb-ox increased: 3.5 (0 +13) p<0.001 and Hb-tot 3.3 (0 +16) p<0.001. Heart rate increased by 9 bpm (p<0.001) from quiet to active sleep while Hb-red, tcpO2, tcCO2 and SO2 did not change significantly.CONCLUSION: These findings demonstrate that sleep state changes correlate with changes in cerebral Hb volume (around 5 %) and therefore must be taken into account during studies of cerebral haemodynamics.