There is no information regarding the relationship between middle cerebral artery flow velocity (Vmca) and cerebral perfusion pressure in pediatric traumatic brain injury (TBI). We determined the incidence of low, normal and high mean Vmca when CPP is > 40 mm Hg in children with severe TBI.
Prospective observational study
Level 1 pediatric trauma center
42 children < 17 years of age with an admission diagnosis of severe TBI (admission Glasgow Coma Scale [GCS] score < 9), TBI on computed tomography (CT) scan, tracheal intubation/mechanical ventilation and intracranial pressure (ICP) monitoring.
Measurements and Main Results
Bilateral middle cerebral arteries were insonated using transcranial Doppler ultrasonography (TCD) to calculate mean Vmca after TBI. Low mean Vmca was defined as Vmca < 2SD and high was defined as mean Vmca > 2SD. Patients were grouped by age (0.8–2.9, 3–5.9, 6–9.9, and 10–16.9 years) and gender to examine the relationship between CPP and low, high or normal mean Vmca. Potential confounders of the relationship between CPP and mean Vmca (ICP, PaCO2, hematocrit [Hct], sedation, fever and impaired autoregulation were examined). Most (33; 79%) children had normal mean Vmca but 4 (9%) patients had low mean Vmca and 5 children (12%) had high mean Vmca despite CPP > 40 mm Hg. There was no difference in potential confounders of the relationship between CPP and mean Vmca except for Hct, which was lower (25 ± 4 [range 21–30]) in children with high mean Vmca. An inverse relationship between mean Vmca and Hct was also found in boys 10–16.9 years.
Both low and/or high mean Vmca occur with CPP > 40 mm Hg in severe pediatric TBI. Of the potential confounders considered, only lower Hct was associated with high mean Vmca.