Continuous intracranial multimodality monitoring comparing local cerebral blood flow, cerebral perfusion pressure, and microvascular resistance

• Published in: Acta neurochirurgica. Supplement Vol. 71; p. 82
• Main Authors: Miller, J I, Chou, M W, Capocelli, A, Bolognese, P, Pan, J, Milhorat, T H
• Format: Journal Article
• Language: English
• Published: Austria 1998
• Subjects: Adolescent; Adult; Blood Pressure - physiology; Brain - blood supply; Brain Injuries - diagnosis; Brain Injuries - physiopathology; Child; Child, Preschool; Critical Care; Female; Homeostasis - physiology; Humans; Laser-Doppler Flowmetry; Male; Microcirculation - physiopathology; Middle Aged; Monitoring, Physiologic - instrumentation; Regional Blood Flow - physiology; Signal Processing, Computer-Assisted - instrumentation; Subarachnoid Hemorrhage - diagnosis; Subarachnoid Hemorrhage - physiopathology; Vascular Resistance - physiology
• ISSN: 0065-1419

Maintaining cerebral perfusion pressure (CPP) above 70 mmHg is currently a mainstay of neurosurgical critical care. Shalmon, et al. recently showed poor correlation between CPP and regional cerebral blood flow (CBF) [1]. To study the relationship between CPP and CBF, at a microvascular level, we retrospectively analyzed multimodality digital data from 12 neurosurgical critical care patients in whom a combined intracranial pressure (ICP)--laser Doppler flowmetry (LDF) probe (Camino, San Diego) had been placed. Over the entire interval of continuous monitoring for all patients, 97% of local CBF data was at ischemic levels below a CPP of 70 mmHg. For CPP above 70 mmHg, local CBF data had considerable dispersion ranging from ischemic (71%), to normal (19%), and hyperemic (10%) levels. Elevated jugular bulb oxyhemoglobin saturation levels (SjO2) complemented intervals of hyperemia. Autoregulation was impaired or absent in all monitored patients. We conclude that with disrupted autoregulation, CPP above 70 mmHg does not necessarily insure adequate levels of cerebral perfusion. Restoration and maintenance of adequate cerebral perfusion should be performed under the guidance of direct CBF monitoring.