Tilting the Head Changes Cerebral Haemodynamics in Neonates

Background: Tilting only the head influences cerebral haemodynamics in term and preterm neonates. Objective: To evaluate near-infrared spectroscopy (NIRS) as a method to detect changes of cerebral oxygenated (HbO 2 ) and deoxygenated haemoglobin (Hb) and ‘cerebral tissue-oxygenation-index’ (cTOI) while tilting. Furthermore to investigate whether the comparison of cTOI and ‘cerebral mixed venous oxygen saturation’ (tiltSvO 2 ), calculated out of the increase of HbO 2 and Hb, improves reproducibility. Methods: During five ‘reapplication’ periods of NIRS optodes on the left forehead of 40 neonates, five tilting manoeuvres of the head were performed. Changes of NIRS parameters during tilting were analysed. The first quality criterion was defined by a linear increase of total haemoglobin (HbT; r 2 > 0.95). The second quality criterion was: cTOI > tiltSvO 2 (= cTOI – tiltSvO 2 > 0). Analysis of variance components and comparison of mean of standard deviations were applied to data after introduction of each quality criterion. Results: While HbO 2 , Hb and HbT showed a linear increase in all neonates during tilting, cTOI did not change. With the introduction of the second criterion, mean cTOI increased from 73.7 ± 6.9 to 75.1 ± 6.9%, mean tiltSvO 2 decreased from 72.6 ± 7.1 to 65.3 ± 6.9% and mean of standard deviations of both parameters decreased. The analysis of variance components showed no significant change. Conclusion: A tilting-down manoeuvre of the head of term and preterm neonates can cause an increase of HbO 2 , Hb and HbT. tiltSvO 2 can be calculated out of these changes. By introducing two quality criteria, reproducibility of cerebral NIRS measurements (cTOI and tiltSvO 2 ) improved.