Intracranial pressure and cerebral perfusion pressure responses to head elevation changes in pediatric traumatic brain injury

Abstract

Objectives: To determine the effect of and dynamic interaction between head elevation on intracranial pressure and cerebral perfusion pressure in severe pediatric traumatic head injury.

Design: Prospective, randomized, interventional cohort study.

Setting: Two tertiary pediatric critical care referral units.

Patients: Ten children admitted with severe traumatic brain injury defined as Glasgow Coma Score ≤ 8 necessitating intracranial pressure monitoring (10 yrs ± 5 SD; range 2-16 yrs).

Interventions: Head elevation was randomly increased or decreased between 0 and 40 degrees from baseline level (30 degrees) in increments or decrements of 10 degrees.

Measurements and main results: Intracranial pressure and arterial blood pressure were continuously recorded in combination with time-stamped clinical notations. Data were available for analysis in eight subjects (seven males and one female; mean age, 10 yrs ± SD 5; range, 2-16 yrs) during 18 protocol sessions. This resulted in a total of 66 head-of-the-bed challenges. To compare results for a given change in head-of-the-bed elevation across age, we transformed head-of-the-bed angle to change in height (cm) at the level of Monro's foramen. An increase in head elevation of 10 cm resulted in an average change in intracranial pressure of -3.9 mm Hg (SD ± 3.2 mm Hg; p < .001), whereas cerebral perfusion pressure remained unchanged (0.1 ± 5.6 mm Hg; p = .957). Individual subjects showed marked variability in intracranial pressure change (range, -8.4 to +1.9 mm Hg/10 cm). The overall regression analysis for intracranial pressure response was change in intracranial pressure = -0.39/cm Δh, r2 = 0.42, and p < .001, where Δh is the change in vertical height at the level of foramen of Monro attributable to a change in the head of the bed.

Conclusions: In severe pediatric traumatic brain injury, the relationship between change in head of the bed and change in intracranial pressure was negative and linear. The lowest intracranial pressure was usually, but not always, achieved at highest head-of-the-bed angles. The effect size of a head-of-the-bed angle change depended, in part, on the subject's height. In contrast, cerebral perfusion pressure was mostly unaffected by head-of-the-bed changes.