Non-invasive estimation of cerebral perfusion pressure using transcranial Doppler ultrasonography in children with severe traumatic brain injury

Abstract

Objective To identify if cerebral perfusion pressure (CPP) can be non-invasively estimated by either of two methods calculated using transcranial Doppler ultrasound (TCD) parameters. Design Retrospective review of previously prospectively gathered data. Setting Pediatric intensive care unit in a tertiary care referral hospital. Patients Twenty-three children with severe traumatic brain injury (TBI) and invasive intracranial pressure (ICP) monitoring in place. Interventions TCD evaluation of the middle cerebral arteries was performed daily. CPP at the time of the TCD examination was recorded. For method 1, estimated cerebral perfusion pressure (CPPe) was calculated as: CPPe = MAP × (diastolic flow (Vd)/ mean flow (Vm)) + 14. For method 2, critical closing pressure (CrCP) was identified as the intercept point on the x-axis of the linear regression line of blood pressure and flow velocity parameters. CrCP/CPPe was then calculated as MAP-CrCP. Measurements and main results One hundred eight paired measurements were available. Using patient averaged data, correlation between CPP and CPPe was significant (r = 0.78, p = < 0.001). However, on Bland-Altman plots, bias was 3.7 mmHg with 95% limits of agreement of − 17 to + 25 for CPPe. Using patient averaged data, correlation between CPP and CrCP/CPPe was significant (r = 0.59, p = < 0.001), but again bias was high at 11 mmHg with wide 95% limits of agreement of − 15 to + 38 mmHg. Conclusions CPPe and CrCP/CPPe do not have clinical value to estimate the absolute CPP in pediatric patients with TBI.

Multimodal and autoregulation monitoring in the neurointensive care unit

“…Similar findings have been reported in nCPP estimation in children with TBI using nICP_CrCP where the ability to identify CPP values below 70 mmHg was excellent (AUC = 0.91; 95% CI: 0.83–0.99) though overestimated true CPP by about 20 mmHg and was less precise for more clinically relevant thresholds of CPP < 60 mmHg and <50 mmHg ( 167 ). In another pediatric TBI study, both nICP_FVd and nICP_CrCP were compared against invasive monitoring and while there was a strong correlation between both models and CPP, each were also associated with wide limits of agreement and unable to discriminate CPP values <50–60 mmHg ( 171 ). Although the performance characteristics of current non-invasive TCD models preclude the ability to precisely measure ICP and CPP, they may still serve as a primary assessment tool in the acute stages of management or in patients who are not candidates for invasive monitoring.…”

ASNM and ASN joint guidelines for transcranial Doppler ultrasonic monitoring: An update

“…Within the intracranial pressure (ICP) ranges above 20 mmHg, the PI has been evaluated as an alternative to direct ICP measurement 16–22 . There is also a significant correlation between the cerebral perfusion pressure and PI 23–25 …”

“…[16][17][18][19][20][21][22] There is also a significant correlation between the cerebral perfusion pressure and PI. [23][24][25]…”

Transcranial Doppler Ultrasound, a Review for the Pediatric Intensivist

“…This formula was applied to a small study of 23 children with severe TBI using intermittent TCD data and was not successful. The average discrepancy was 3.7 mmHg but limits of agreement were −17 to +25 mmHg [ 32 ]. A similar study was performed applying the same formula to a group of 10 children with acute brain injury requiring an ICP monitor ( n = 3 with TBI, n = 7 with intracranial hemorrhage) to non-invasively estimate ICP based on intermittent TCD data [ 33 ].…”