Cerebral blood flow autoregulation during intracranial hypertension: a simple, purely hydraulic mechanism?
Childs Nerv Syst
; 25(3): 325-35; discussion 337-40, 2009 Mar.
Article
en En
| MEDLINE
| ID: mdl-19152096
ABSTRACT
OBJECTIVE:
In this paper, we re-propose the role of a hydraulic mechanism, acting where the bridging veins enter the dural sinuses in cerebral blood flow (CBF) autoregulation. MATERIALS ANDMETHODS:
We carried out an intraventricular infusion in ten albino rabbits and increased intracranial pressure (ICP) up to arterial blood pressure (ABP) levels. We measured CBF velocity by an ultrasound probe applied to a by-pass inserted in a carotid artery and recorded ICP by an intraventricular needle. Diastolic and pulsatile ICP and ABP values were analyzed from basal conditions up to brain tamponade and vice versa.CONCLUSIONS:
A biphasic pattern of pulsatile intracranial pressure (pICP) was observed in all trials. Initially, until the CBF velocity remained constant, pICP increased (from 1.2 to 5.4 mmHg) following a rise in diastolic intracranial pressure (dICP); thereafter, in spite of a further rise in dICP, pICP decreased (2.87 mmHg) following CBF velocity reduction until intracranial circulation arrest (pICP=1.2 mmHg). A specular pattern was observed when the intraventricular infusion was stopped and CBF velocity returned to basal levels. These findings can be interpreted as indicating a hydraulic mechanism. Initially, when CBF is still constant, pICP rise is due to an increase in venous outflow resistance; subsequently, when CBF decreases following a further increase in venous outflow resistance, the vascular engorgement produces an arteriolar vasodilation. This vasodilation determines an increase in vascular wall stiffness, thus reducing pulse transmission to surrounding subarachnoid spaces.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Velocidad del Flujo Sanguíneo
/
Flujo Pulsátil
/
Encéfalo
/
Circulación Cerebrovascular
/
Hipertensión Intracraneal
/
Homeostasis
Tipo de estudio:
Etiology_studies
Límite:
Animals
Idioma:
En
Revista:
Childs Nerv Syst
Asunto de la revista:
NEUROLOGIA
/
PEDIATRIA
Año:
2009
Tipo del documento:
Article
País de afiliación:
Italia