Summary
Ultrasonic “time-of-flight” monitor (Vittamed) was used for continuous monitoring of intracranial blood volume (IBV) pulse, respiratory, slow waves and cerebrovascular autoregulation (CA). The objectives are to compare of invasively and non-invasively monitored slow intracranial waves and CA of ICU patients and to evaluate the phase shift between ABP and IBV respiratory waves as a possible estimator of CA.
CA monitoring has been performed in 13 patients with severe TBI (age mean/range 30.5/(18–64)). Data were collected from 87 one-hour sessions of simultaneous invasive and non-invasive wave monitoring and from 53 one-hour sessions of invasive and non-invasive CA monitoring.
High correlation (R>0.9) has been obtained between invasively and non-invasively recorded intracranial slow waves. Bland Altman difference between invasively and non-invasively recorded intracranial slow waves is clinically not significant (mean=−0.07, SD=0.089, α=0.05). Agreement has been confirmed between invasive and non-invasive CA monitoring data in a wide range of R = [−0.85; +0.96].
Hypothesis of the coincidence of invasive and non-invasive CA assessment is accepted (p<0.05).
Phase shift monitoring of permanent respiratory ABP waves and IBV waves permit continuous non-invasive CA estimation without unnatural physical or pharmacological stimulations of CA system.