Introduction: Compromised cerebrovascular autoregulation (CA) is a consequence of acute cerebrovascular events and/or immaturity of CA. We studied CA capacity in response to tilting in healthy term neonates longitudinally using a transcranial Doppler system.

Methods: 14 healthy neonates CBFV were assessed synchronously in both MCA for > 30 min at the age < 36 h and at 4-6 wks. CA-reactivity was tested with a tilting manoever: the infants were tilted by 40° from supine to orthostatic head-up position, kept tilted for 2 min and then tilted back. CBFV were analysed at baseline, 20 sec and 2 min; statistical analysis was done by Wilcoxon-signed-rank-test. In addition to CBFV, on-line heart rate, breathing movements and oxygen saturation were recorded. Video tracings were performed in order to detect artefacts.

Results: At the age < 36h, all neonates showed significantly decreased values of Vdiast in orthostatic position at 20 sec(Vdiast: 74% ±21, p < 0.01) and 2 min (Vdiast: 83%±25; p < 0.003) as compared to respective values obtained at the age of 4-6 wks (Vdiast 20 sec: 101% ±9; 2 min: 97% ±14). Significant alterations were also observed in mean velocities, systolic velocities did not show any significant difference.

Conclusion: Non-invasive assessment of CA is possible by tilting and continuous Doppler sonography of CBFV. CA capacity of term neonates improves with advancing age.

Supported by the Austrian Research Foundation (FWF-Nr-9342) & DWL Instruments, Germany