Abstract
Background: Continuous monitoring of dynamic cerebral autoregulation, using a moving correlation index of cerebral perfusion pressure and mean middle cerebral artery flow velocity, may be useful in patients with severe traumatic brain injury to guide treatment, and has been shown to be of prognostic value.
Objective: To compare an index of dynamic cerebral autoregulation (Mx) with an index of static cerebral autoregulation (sRoR).
Methods: Mx was validated in a prospective comparative study against sRoR, using 83 testing sessions in 17 patients with traumatic brain injury. sRoR and Mx were calculated simultaneously during pharmacologically induced blood pressure variations.
Results: Mx was significantly correlated with sRoR (R = -0.78, p < 0.05). Nine patients were found to have failure of cerebral autoregulation, with an sRoR value < 50%. If an Mx value of 0.3 was used as the cut off point for failure of cerebral autoregulation, this index had 100% sensitivity and 90% specificity for demonstrating failure of autoregulation compared with the sRoR. An increase in cerebral blood flow velocity correlated significantly with Mx (R = 0.73, p < 0.05) but not with cerebral perfusion pressure (R = 0.41).
Conclusions: Dynamic and static cerebral autoregulation are significantly correlated in traumatic brain injury. Cerebral autoregulation can be monitored continuously, graded, and reliably assessed using a moving correlation analysis of cerebral perfusion pressure and cerebral blood flow velocity (Mx). The Mx index can be used to monitor cerebral blood flow regulation. It is useful in traumatic brain injury because it does not require any external stimulus.
Full Text
The Full Text of this article is available as a PDF (107.9 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Aaslid R., Lindegaard K. F., Sorteberg W., Nornes H. Cerebral autoregulation dynamics in humans. Stroke. 1989 Jan;20(1):45–52. doi: 10.1161/01.str.20.1.45. [DOI] [PubMed] [Google Scholar]
- Czosnyka M., Smielewski P., Kirkpatrick P., Menon D. K., Pickard J. D. Monitoring of cerebral autoregulation in head-injured patients. Stroke. 1996 Oct;27(10):1829–1834. doi: 10.1161/01.str.27.10.1829. [DOI] [PubMed] [Google Scholar]
- Czosnyka M., Smielewski P., Piechnik S., Steiner L. A., Pickard J. D. Cerebral autoregulation following head injury. J Neurosurg. 2001 Nov;95(5):756–763. doi: 10.3171/jns.2001.95.5.0756. [DOI] [PubMed] [Google Scholar]
- Dawson S. L., Blake M. J., Panerai R. B., Potter J. F. Dynamic but not static cerebral autoregulation is impaired in acute ischaemic stroke. Cerebrovasc Dis. 2000 Mar-Apr;10(2):126–132. doi: 10.1159/000016041. [DOI] [PubMed] [Google Scholar]
- Giller C. A. A bedside test for cerebral autoregulation using transcranial Doppler ultrasound. Acta Neurochir (Wien) 1991;108(1-2):7–14. doi: 10.1007/BF01407660. [DOI] [PubMed] [Google Scholar]
- Heckmann J. G., Hilz M. J., Hagler H., Mück-Weymann M., Neundörfer B. Transcranial Doppler sonography during acute 80 degrees head-down tilt (HDT) for the assessment of cerebral autoregulation in humans. Neurol Res. 1999 Jul;21(5):457–462. [PubMed] [Google Scholar]
- Larsen F. S., Olsen K. S., Hansen B. A., Paulson O. B., Knudsen G. M. Transcranial Doppler is valid for determination of the lower limit of cerebral blood flow autoregulation. Stroke. 1994 Oct;25(10):1985–1988. doi: 10.1161/01.str.25.10.1985. [DOI] [PubMed] [Google Scholar]
- Lewis S. B., Wong M. L., Bannan P. E., Piper I. R., Reilly P. L. Transcranial Doppler identification of changing autoregulatory thresholds after autoregulatory impairment. Neurosurgery. 2001 Feb;48(2):369–376. [PubMed] [Google Scholar]
- Mahony P. J., Panerai R. B., Deverson S. T., Hayes P. D., Evans D. H. Assessment of the thigh cuff technique for measurement of dynamic cerebral autoregulation. Stroke. 2000 Feb;31(2):476–480. doi: 10.1161/01.str.31.2.476. [DOI] [PubMed] [Google Scholar]
- Mascia L., Andrews P. J., McKeating E. G., Souter M. J., Merrick M. V., Piper I. R. Cerebral blood flow and metabolism in severe brain injury: the role of pressure autoregulation during cerebral perfusion pressure management. Intensive Care Med. 2000 Feb;26(2):202–205. doi: 10.1007/s001340050046. [DOI] [PubMed] [Google Scholar]
- Piechnik S. K., Yang X., Czosnyka M., Smielewski P., Fletcher S. H., Jones A. L., Pickard J. D. The continuous assessment of cerebrovascular reactivity: a validation of the method in healthy volunteers. Anesth Analg. 1999 Oct;89(4):944–949. doi: 10.1097/00000539-199910000-00023. [DOI] [PubMed] [Google Scholar]
- Smielewski P., Czosnyka M., Kirkpatrick P., Pickard J. D. Evaluation of the transient hyperemic response test in head-injured patients. J Neurosurg. 1997 May;86(5):773–778. doi: 10.3171/jns.1997.86.5.0773. [DOI] [PubMed] [Google Scholar]
- Strebel S., Lam A. M., Matta B., Mayberg T. S., Aaslid R., Newell D. W. Dynamic and static cerebral autoregulation during isoflurane, desflurane, and propofol anesthesia. Anesthesiology. 1995 Jul;83(1):66–76. doi: 10.1097/00000542-199507000-00008. [DOI] [PubMed] [Google Scholar]
- Tiecks F. P., Douville C., Byrd S., Lam A. M., Newell D. W. Evaluation of impaired cerebral autoregulation by the Valsalva maneuver. Stroke. 1996 Jul;27(7):1177–1182. doi: 10.1161/01.str.27.7.1177. [DOI] [PubMed] [Google Scholar]
- Tiecks F. P., Lam A. M., Aaslid R., Newell D. W. Comparison of static and dynamic cerebral autoregulation measurements. Stroke. 1995 Jun;26(6):1014–1019. doi: 10.1161/01.str.26.6.1014. [DOI] [PubMed] [Google Scholar]