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 cer ebral blood Volume (CBV) during periodic breathing in healthy term infants by means of near infrared spectroscopy (NIRS). Polygraphy included electroc ardiogram, electrooculogram, heart rate, oxygen saturation, side stream cap nography, two respiratory effort sensors, a movement sensor, and NIRS. Duri ng 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 cH bD appeared in 98%, cyclical variations of cHbtot appeared in 42% of all ap noeas. During phases of apnoea, a mean decrease of cHbD of -3.45 mu mol/l o ccurred 1.75 seconds after onset of apnoea, and a mean decrease of cHbtot o f -0.79 mu mol/occurred 0.74 seconds after onset of apnoea. During these ap noeas, 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 w as a tendency that CytOx values decreased during periodic breathing, the am ount ;of decrease was -0.32 mu mol/l. In conclusion, the present study was able to show for the first time that t here is cyclical desaturation and reoxygenation of cerebral blood during pe riodic breathing. Cyclical changes in CBV in association with periodic apno ea occurred only in 42% of apnoea.