Tilting the head changes cerebral haemodynamics in neonates

Area of Science:

• Neonatal physiology and cerebral hemodynamics.
• Medical instrumentation and signal processing.

Background:

• Head tilting is known to influence cerebral hemodynamics in both term and preterm neonates.
• Understanding these hemodynamic changes is crucial for neonatal care and monitoring.

Purpose of the Study:

• To evaluate near-infrared spectroscopy (NIRS) for detecting changes in cerebral oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (Hb), and cerebral tissue-oxygenation-index (cTOI) during head tilting.
• To investigate if comparing cTOI with calculated cerebral mixed venous oxygen saturation (tiltSvO2) enhances measurement reproducibility.

Main Methods:

• NIRS optodes were applied to the foreheads of 40 neonates, with five head tilting maneuvers performed during each of five NIRS reapplication periods.
• Changes in NIRS parameters (HbO2, Hb, HbT, cTOI) were analyzed.
• Two quality criteria were established: linear increase in total hemoglobin (HbT; r(2) > 0.95) and cTOI > tiltSvO2. Analysis of variance components and mean standard deviations were used.

Main Results:

• Head tilting consistently increased HbO2, Hb, and HbT in all neonates.
• Initially, cTOI did not change during tilting. However, after applying the second quality criterion, mean cTOI increased (73.7% to 75.1%), while mean tiltSvO2 decreased (72.6% to 65.3%).
• The mean of standard deviations for both cTOI and tiltSvO2 decreased, indicating improved reproducibility.

Conclusions:

• Head-down tilting in neonates causes measurable increases in HbO2, Hb, and HbT, allowing for the calculation of tiltSvO2.
• Implementing specific quality criteria significantly improves the reproducibility of cerebral NIRS measurements, including cTOI and tiltSvO2.
• NIRS is a valuable tool for assessing cerebral hemodynamics in neonates during positional changes.