Changes in cerebral blood volume with changes in position in awake and anesthetized subjects.

Autor:	Lovell AT; Department of Surgery, University College London Medical School, The Middlesex Hospital, London, UK., Marshall AC, Elwell CE, Smith M, Goldstone JC
Jazyk:	angličtina
Zdroj:	Anesthesia and analgesia [Anesth Analg] 2000 Feb; Vol. 90 (2), pp. 372-6.
DOI:	10.1097/00000539-200002000-00025
Abstrakt:	Unlabelled: Changes in posture affect cerebral blood volume (CBV), and moderate head-up tilt is used as a therapeutic maneuver to reduce CBV and intracranial pressure. However, CBV is rarely measured in the clinical setting. Near-infrared spectroscopy allows real-time bedside monitoring of cerebral hemodynamics, and we have used this technique to measure changes in CBV with changes in posture in 10 normal subjects and 10 propofol-anesthetized patients. In the awake subjects, changes in CBV were correlated with the degree of table tilt. CBV decreased with 18 degrees head-up tilt and increased with 18 degrees head-down tilt (P < 0.0001, r = -0.924). In anesthetized patients, there were differences between head-up and head-down tilt. In the head-down position, CBV was also correlated with the degree of table tilt (P < 0.001, r = -0.782), whereas there was a clinically insignificant reduction in CBV in the head-up position. Near-infrared spectroscopy allows continuous, real time measurement of changes in CBV at the bedside. Implications: Near-infrared spectroscopy, a bedside technique, has been used to measure changes in cerebral blood volume in normal subjects. We have used the same technique in anesthetized patients and have shown that, when a patient is placed in the head up position, the decrease in cerebral blood volume is attenuated, relative to normal subjects.
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu