Changes in cerebral blood volume and cerebral oxygenation during periodic breathing in term infants

The present study is an analysis of changes in cerebral oxygenation and cerebral blood Volume (CBV) during periodic breathing in healthy term infants by means of near infrared spectroscopy (NIRS). Polygraphy included electrocardiogram, electrooculogram, heart rate, oxygen saturation, side stream capnography, two respiratory effort sensors, a movement sensor, and NIRS. During periodic breathing analysis of behaviour of total haemoglobin (cHbtot), Delta CBV, the haemoglobin oxygenation index (cHbD), and cytochrome oxidase (CytOx) was performed. In ten healthy term infants 30 cycles of periodic breathing with a mean of 10 apnoeas per cycle were analysed. Corresponding cyclical variations of cHbD appeared in 98%, cyclical variations of cHbtot appeared in 42% of all apnoeas. During phases of apnoea, a mean decrease of cHbD of -3.45 mu mol/l occurred 1.75 seconds after onset of apnoea, and a mean decrease of cHbtot of -0.79 mu mol/occurred 0.74 seconds after onset of apnoea. During these apnoeas, the Delta CBV was -44 mu/100 g brain. During phases of ventilation, there was an increase of cHbD and cHbtot to the pre-apnoeic levels. There was a tendency that CytOx values decreased during periodic breathing, the amount ;of decrease was -0.32 mu mol/l. In conclusion, the present study was able to show for the first time that there is cyclical desaturation and reoxygenation of cerebral blood during periodic breathing. Cyclical changes in CBV in association with periodic apnoea occurred only in 42% of apnoea.