A noninvasive estimation of cerebral perfusion pressure using critical closing pressure

• Published in: Journal of neurosurgery Vol. 123; no. 3; p. 638
• Main Authors: Varsos, Georgios V, Kolias, Angelos G, Smielewski, Peter, Brady, Ken M, Varsos, Vassilis G, Hutchinson, Peter J, Pickard, John D, Czosnyka, Marek
• Format: Journal Article
• Language: English
• Published: United States 01.09.2015
• Subjects: Adolescent; Adult; Blood Flow Velocity - physiology; Blood Pressure - physiology; Cerebrovascular Circulation - physiology; Craniocerebral Trauma - diagnostic imaging; Craniocerebral Trauma - physiopathology; Female; Humans; Intracranial Pressure - physiology; Male; Middle Aged; Monitoring, Physiologic; Retrospective Studies; Sensitivity and Specificity; Ultrasonography, Doppler, Transcranial; Young Adult; IQR = interquartile range; TBI = traumatic brain injury; AUC = area under the curve; TAU = time constant of the cerebrovascular arterial bed; ABP = arterial blood pressure; CVR = cerebrovascular resistance; CPP = cerebral perfusion pressure; MCA = middle cerebral artery; eCPP = noninvasive estimator of CPP; ICP = intracranial pressure; vascular disorders; transcranial Doppler ultrasonography; GOS = Glasgow Outcome Scale; critical closing pressure; CBF = cerebral blood flow; FV = flow velocity; GCS = Glasgow Coma Scale; TCD = transcranial Doppler; ROC = receiver operating characteristic; noninvasive model; CrCP = critical closing pressure; cerebral perfusion pressure; nICP = noninvasive estimator of ICP
• DOI: 10.3171/2014.10.JNS14613

Cerebral blood flow is associated with cerebral perfusion pressure (CPP), which is clinically monitored through arterial blood pressure (ABP) and invasive measurements of intracranial pressure (ICP). Based on critical closing pressure (CrCP), the authors introduce a novel method for a noninvasive estimator of CPP (eCPP). Data from 280 head-injured patients with ABP, ICP, and transcranial Doppler ultrasonography measurements were retrospectively examined. CrCP was calculated with a noninvasive version of the cerebrovascular impedance method. The eCPP was refined with a predictive regression model of CrCP-based estimation of ICP from known ICP using data from 232 patients, and validated with data from the remaining 48 patients. Cohort analysis showed eCPP to be correlated with measured CPP (R = 0.851, p < 0.001), with a mean ± SD difference of 4.02 ± 6.01 mm Hg, and 83.3% of the cases with an estimation error below 10 mm Hg. eCPP accurately predicted low CPP (< 70 mm Hg) with an area under the curve of 0.913 (95% CI 0.883-0.944). When each recording session of a patient was assessed individually, eCPP could predict CPP with a 95% CI of the SD for estimating CPP between multiple recording sessions of 1.89-5.01 mm Hg. Overall, CrCP-based eCPP was strongly correlated with invasive CPP, with sensitivity and specificity for detection of low CPP that show promise for clinical use.