Background: Cerebral autoregulation is impaired in a multitude of neurological conditions.
Increasingly, clinical studies are correlating the nature of this impairment with
prognostic markers. In acute intracerebral hemorrhage, impairment of cerebral autoregulation
has been associated with worsening clinical outcomes including poorer Glasgow Coma
Score and larger hematoma volume. Hypocapnia has been shown to improve cerebral autoregulation
despite concerns over hypoperfusion and consequent ischemic risks, and it is therefore
hypothesized that hypocapnia (via hyperventilation) in acute intracerebral hemorrhage
may improve cerebral autoregulation and consequently clinical outcome.Aims: To assess
the feasibility and acceptability of the first cerebral autoregulation-targeted intervention
in acute intracerebral hemorrhage utilizing a simple bed-side hyperventilatory maneuver.Methods:
Twelve patients with acute intracerebral hemorrhage within 48 h of onset were enrolled.
The experimental setup measured cerebral blood flow velocity (transcranial Doppler),
blood pressure (Finometer), and end-tidal CO2 (EtCO2, capnography) at baseline, and
in response to hypocapnia (-5 mmHg below baseline) achieved via a 90-s hyperventilatory
maneuver. Cerebral autoregulation was evaluated with transfer function analysis and
autoregulatory index calculations.Results: We observed tolerance to the protocol in
a cohort of mild (National Institutes of Health Scale 4) supratentorial intracerebral
hemorrhage patients with small volume hematomas without intraventricular extension.
Importantly, a significant difference was noted between ipsilateral autoregulatory
index at baseline 4.8 (1.7) and autoregulatory index during hypocapnic intervention
7.0 (0.8) (p = 0.0004), reflecting improved cerebral autoregulation, though a dose-dependent
effect of EtCO2 on autoregulatory index was not observed.Conclusions: In this small
study, there was no observed effect on 14-day death and disability in recruited participants.
This is the first report of improvement in cerebral autoregulation in acute intracerebral
hemorrhage using a non-invasive interventional maneuver, through induction of hypocapnia