Experimental studies have shown that, during the initial bleed, cerebral autoregulation is operating.30 Both autoregulation and CO2 response are impaired in the acute stage of SAH.6,13,27 Some authors found both variables still impaired about 1 week later,2,18,28 while others demonstrated that animals in neurological Grades I and II (classification of Hunt and Hess10) had better recovery of autoregulation and CO2 reactivity than those in Grades III and IV.12 A few human studies have suggested a correlation between defective cerebrovascular reactivity and cerebral vasospasm7,11,14 and raised intracranial pressure.7
We have previously reported that regional cerebral blood flow (rCBF) and cerebral metabolic rate of oxygen (CMRO2) are decreased following SAH, and that this decrease correlates with the degree of angiographic vasospasm.34 In the present study, we have investigated the cerebral autoregulation and the CO2 reactivity in patients with recent SAH, with special reference to cerebral vasospasm.
Lassen NA: The luxury-perfusion syndrome and its possible relation to acute metabolic acidosis localised within the brain. Lancet 2:1113–11151966Lassen NA: The luxury-perfusion syndrome and its possible relation to acute metabolic acidosis localised within the brain. Lancet 2:
Lundberg N: Continuous recording and control of ventricular fluid pressure in neurosurgical practice. Acta Psychiatr Neurol Scand 36 (Suppl 149):1–1931960Lundberg N: Continuous recording and control of ventricular fluid pressure in neurosurgical practice. Acta Psychiatr Neurol Scand 36 (Suppl 149):
Mickey BVorstrup SVoldby Bet al: Serial measurement of regional cerebral blood flow in patients with SAH using 133Xe inhalation and emission computerized tomography. J Neurosurg 60:916–9221984133Xe inhalation and emission computerized tomography. J Neurosurg 60:
Olesen JPaulson OBLassen NA: Regional cerebral blood flow in man determined by the initial slope of the clearance of intra-arterially injected 133Xe. Theory of the method, normal values, error of measurement, correction for remaining radioactivity, relation to other flow parameters and response to Paco2 changes. Stroke 2:519–54019711332 changes. Stroke 2:
Olsen TSLarsen BSkriver EBet al: Focal cerebral ischemia measured by the intra-arterial 133Xenon method. Limitations of 2-dimensional blood flow measurements. Stroke 12:736–7441981133Xenon method. Limitations of 2-dimensional blood flow measurements. Stroke 12:
Paulson OBStrandgaard S: Regulation of cerebral blood flow in health and diseaseTissot R (ed): Etats Déficitaires Cérébraux Liés à l'Âge. Proceedings of the Sixth Bel-Air Symposium. Geneva: George et Cie198029–45Etats Déficitaires Cérébraux Liés à l'Âge. Proceedings of the Sixth Bel-Air Symposium.
Petruk KCWeir BKOverton TRet al: The effect of graded hypocapnia and hypercapnia on regional cerebral blood flow and cerebral vessel caliber in the rhesus monkey: study of cerebral hemodynamics following subarachnoid hemorrhage and traumatic internal carotid spasm. Stroke 5:230–2461974Stroke 5:
Pickard JDBoisvert DPJGraham DIet al: Late effects of subarachnoid haemorrhage on the response of the primate cerebral circulation to drug-induced changes in arterial blood pressure. J Neurol Neurosurg Psychiatry 42:899–9031979J Neurol Neurosurg Psychiatry 42: