Midline shift in patients with closed traumatic brain injury may be driven by cerebral perfusion pressure not intracranial pressure

Abstract

BACKGROUND:

In traumatic brain injury (TBI), swelling may disturb the potentially uniform pressure distribution in the brain, producing sustained intercompartmental pressure gradients which may associate with midline shift. The presence of pressure gradients is often neglected since bilateral invasive intracranial pressure (ICP) monitoring is not usually considered because of risks and high costs. We evaluated the presence of interhemispheric pressure gradients using bilateral transcranial Doppler (TCD) as means for non-invasive ICP (nICP) monitoring in TBI patients presenting midline shift.

METHODS:

From a retrospective cohort of 97 TBI patients with arterial blood pressure (ABP), ICP and bilateral TCD monitoring, 24 presented unilateral lesion and midline shift confirmed by computer tomography. nICP and non-invasive cerebral perfusion pressure (nCPP) on the left and right brain hemispheres were retrospectively calculated using a mathematical model associating TCD-derived cerebral blood flow velocity and ABP.

RESULTS:

The nCPP difference was correlated with midline shift (R=-0.34, p<.01) showing a tendency to record higher CPP at the side of expansion. Accordingly, nICP at the side of expansion was significantly lower in comparison to the compressed side (18.86 [±5.71] mmHg (mean ± standard deviation) versus 20.30 [±6.78] mmHg for expansion and compressed sides, respectively). Subsequently, nCPP was greater on the side of brain expansion (79.48±7.84, 78.03±8.93 mmHg [p<.01], for expansion and compressed sides, respectively).

CONCLUSIONS:

TCD-based interhemispheric nCPP difference showed significant correlation with midline shift. Cerebral perfusion pressure was greater on the side of brain expansion, acting as the driving force to shift brain structures.

IMPORTANTE ARTIGO EXPANDINDO OS CONHECIMENTOS DA MONITORAÇÃO NÃO INVASIVA DA PRESSÃO INTRACRANIANA ATRAVÉS DO DOPPLER TRANSCRANIANO E PROVENDO DADOS PARA INTERVENÇÃO ATRAVÉS DO MANUSEIO DA VOLEMIA ENCEFÁLICA NO CONTROLE  DOS DESVIOS DE TECIDO CEREBRAL (HÉRNIAS) PROMOVIDOS  POR ASSIMETRIAS NA PRESSÃO DE PERFUSÃO CEREBRAL.

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Velocity Criteria for Intracranial Stenosis Revisited An International Multicenter Study of Transcranial Doppler and Digital Subtraction Angiography

Abstract

BACKGROUND AND PURPOSE:

Intracranial atherosclerotic disease is associated with a high risk of stroke recurrence. We aimed to determine accuracy of transcranial Doppler screening at laboratories that share the same standardized scanning protocol.

METHODS:

Patients with symptoms of cerebral ischemia were prospectively studied. Stroke Outcomes and Neuroimaging of IntracranialAtherosclerosis (SONIA) criteria were used for identification of ≥50% stenosis. We determined velocity cutoffs for ≥70% stenosis on digitalsubtraction angiography by Warfarin-Aspirin Symptomatic Intracranial Disease criteria and evaluated novel stenotic/prestenotic ratio and low-velocity criteria.

RESULTS:

A total of 102 patients with intracranial atherosclerotic disease (age 57±13 years; 72% men; median National Institutes of Health Stroke Scale 3, interquartile range 6) provided 690 transcranial Doppler/digital subtraction angiography vessel pairs. On digital subtractionangiography, ≥50% stenosis was found in 97 and ≥70% stenosis in 62 arteries. Predictive values for transcranial Doppler SONIA criteria were similar (P>0.9) between middle cerebral artery (sensitivity 78%, specificity 93%, positive predictive value 73%, negative predictive value 94%, and overall accuracy 90%) and vertebral artery/basilar artery (69%, 98%, 88%, 93%, and 92%). As a single velocity criterion, most sensitive mean flow velocity thresholds for ≥70% stenosis were: middle cerebral artery>120 cm/s (71%) and vertebral artery/basilar artery>110 cm/s (55%). Optimal combined criteria for ≥70% stenosis were: middle cerebral artery>120 cm/s, or stenotic/prestenotic ratio≥3, or low velocity(sensitivity 91%, specificity 80%, receiver operating characteristic 0.858), and vertebral artery/basilar artery>110 cm/s or stenotic/prestenotic ratio≥3 (60%, 95%, 0.769, respectively).

CONCLUSIONS:

At laboratories with a standardized scanning protocol, SONIA mean flow velocity criteria remain reliably predictive of ≥50% stenosis. Novel velocity/ratio criteria for ≥70% stenosis increased sensitivity and showed good agreement with invasive angiography.

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ARTIGO ESTABELECE CORRELAÇÃO  DE ESTENOSE INTRACRANIANA ENTRE O DOPPLER TRANSCRANIANO E A  ANGIOGRAFIA CEREBRAL EM PACIENTES PORTADORES DE AVCI, AIT.

VALORES DE ESTENOSE DOS ESTUDOS SONIA E SAMMPRIS FORAM REVISITADOS E ADICIONADOS  RAZÕES DE VELOCIDADES ENTRE OS SEGMENTOS PRÉ ESTENÓTICOS E ESTENÓTICOS AFIM DE MELHORAR A PREDIÇÃO.

EXCELENTE ARTIGO PARA APLICAÇÃO DIÁRIA NO CUIDADO DOS PACIENTES VÍTIMAS DE AVCI.

Optimal cerebral perfusion pressure via transcranial Doppler in TBI: application of robotic technology

Abstract

Individualized cerebral perfusion pressure (CPP) targets may be derived via assessing the minimum of the parabolic relationship between an index of cerebrovascular reactivity and CPP. This minimum is termed the optimal CPP (CPPopt), and literature suggests that the further away CPP is from CPPopt, the worse is clinical outcome in adult traumatic brain injury (TBI). Typically, CPPopt estimation is based on intracranial pressure (ICP)-derived cerebrovascular reactivity indices, given ICP is commonly measured and provides continuous long duration data streams. The goal of this study is to describe for the first time the application of robotic transcranial Doppler (TCD) and the feasibility of determining CPPopt based on TCD autoregulation indices.

KEYWORDS:

CPP optimum; Robotic transcranial Doppler; TBI; TCD; Traumatic brain injury

PMID:

 

30267208

 

DOI:

 

10.1007/s00701-018-3687-5

Relationship Between Brain Pulsatility and Cerebral Perfusion Pressure

Artigo publicado na Neurocritical Care reforça o entendimento sobre o Índice de Pulsatilidade Cerebral como uma ferramenta complexa composta por vários parâmetros mutualmente independentes.

Leia o artigo na integra e entenda os conceitos.

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