Monitoring and interpretation of intracranial pressure

Czosnyka, Marek; Pickard, John D.

doi:10.1136/jnnp.2003.033126

Cited by 673 publications

(524 citation statements)

References 77 publications

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“…35 Hyperventilation reduces cerebral blood volume and consequently decreases ICP. 36 But the reduction of ICP induced by hyperventilation in patients without cerebrovascular disease is expected to be small.…”

Section: Discussionmentioning

confidence: 99%

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

Grüne

Kazmaier

Stolker

et al. 2015

J Cereb Blood Flow Metab

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In addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO 2 -induced changes in CBF, CVR, CPPe, ZFP, and RAP is not fully understood. In a controlled crossover trial, we investigated 10 anesthetized patients aiming at PaCO 2 levels of 30, 37, 43, and 50 mm Hg. Cerebral blood flow was measured with a modified Kety-Schmidt-technique. Zero flow pressure and RAP was estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. Effective cerebral perfusion pressure was calculated as the difference between mean arterial pressure and ZFP, CVR as the ratio CPPe/CBF. Statistical analysis was performed by one-way RM-ANOVA. When comparing hypocapnia with hypercapnia, CBF showed a significant exponential reduction by 55% and mean V MCA by 41%. Effective cerebral perfusion pressure linearly decreased by 17% while ZFP increased from 14 to 29 mm Hg. Cerebrovascular resistance increased by 96% and RAP by 39%; despite these concordant changes in mean CVR and Doppler-derived RAP correlation between these variables was weak (r = 0.43). In conclusion, under general anesthesia hypocapnia-induced reduction in CBF is caused by both an increase in CVR and a decrease in CPPe, as a consequence of an increase in ZFP.

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Section: Discussionmentioning

confidence: 99%

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

Grüne

Kazmaier

Stolker

et al. 2015

J Cereb Blood Flow Metab

View full text Add to dashboard Cite

show abstract

“…In the case of the RAP index, it was calculated as the correlation coefficient between mean ICP and the estimated amplitude of the first harmonic of the pulse waveform (AMP) during the first 4 minutes of the recording. For this task, the signal was divided into 6-s length nonoverlapping windows [2,12,37]. In each 6-s length window, mean ICP was calculated and AMP was estimated as the squared root of the power of the first harmonic component [38].…”

Section: Correlation With Patient Datamentioning

confidence: 99%

“…Therefore, 40 consecutive data points were considered in the calculation of the correlation coefficient [2,12,37].…”

Section: Correlation With Patient Datamentioning

confidence: 99%

“…Traditionally, therapies derived from ICP monitoring relied on the time-averaged mean, as this parameter has been related to pathological patterns [12]. However, it does not account for all the information contained in the ICP waveform and does not clarify the pathophysiology underlying NPH [8,12].…”

Section: Introductionmentioning

confidence: 99%

“…However, it does not account for all the information contained in the ICP waveform and does not clarify the pathophysiology underlying NPH [8,12]. For this reason, prior research has been devoted to the development of alternatives to study ICP.…”

Section: Introductionmentioning

confidence: 99%

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Effect of infusion tests on the dynamical properties of intracranial pressure in hydrocephalus

García

Poza

Bachiller

et al. 2016

Computer Methods and Programs in Biomedicine

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Analysis of Normal High-Frequency Intracranial Pressure Values and Treatment Threshold in Neurocritical Care Patients

et al. 2020

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IMPORTANCE Intracranial pressure (ICP) elevation is a compartment syndrome that impairs blood flow to the brain. Despite the importance of ICP values in neurocritical care, normal ICP values and the precise ICP threshold at which treatment should be initiated remain uncertain.OBJECTIVE To refine our understanding of normal ICP values and determine the ICP threshold most strongly associated with outcome. Prospective observational study (2004Prospective observational study ( -2010, with outcomes determined at hospital discharge. The study included neurocritical care patients from a single level I trauma center, San Francisco General Hospital. Three hundred eighty-three patients had a traumatic brain injury with or without craniectomy; 140 patients had another indication for ICP monitoring. Consecutive patients were studied. Data analyses were completed between March 2015 and December 2019. DESIGN, SETTING, AND PARTICIPANTSEXPOSURES Five hundred twenty-three ICP-monitored patients.MAIN OUTCOMES AND MEASURES A computer system prospectively and automatically collected 1-minute physiologic data from patients in the intensive care unit during a 6-year period. Mean ICP was calculated, as was the proportion of ICP values greater than thresholds from 1 to 80 mm Hg in 1-mm Hg increments. The association between these measures and outcome was explored for various epochs up to 30 days from the time of injury. A principal component analysis was used to explore physiologic changes at various ICP thresholds, and elastic net regression was used to identify ICP thresholds most strongly associated with Glasgow Outcome Scale score at discharge. RESULTSOf the 523 studied patients, 70.7% of studied patients were men (n = 370) and 72.1% had a traumatic brain injury (n = 377). A total of 4 090 964 1-minute ICP measurements were recorded for the included patients (7.78 years of recordings). Intracranial pressure values of 8 to 9 mm Hg were most commonly recorded and could possibly reflect normal values. The principal component analysis suggested state shifts in the physiome occurred at ICPs greater than 19 mm Hg and 24 mm Hg. Elastic net regression identified an ICP threshold of 19 mm Hg as most robustly associated with outcome when considering all neurocritical care patients, patients with TBI, and patients with TBI who underwent craniectomy. Intracranial pressure values greater than 19 mm Hg were associated with mortality, while lower values were associated with outcome in surviving patients. CONCLUSIONS AND RELEVANCEThis study provides insight into what normal ICP values could be. An ICP threshold of 19 mm Hg was robustly associated with outcome in studied patients, although lower ICP values were associated with outcome in surviving patients.

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Monitoring and interpretation of intracranial pressure

Cited by 673 publications

References 77 publications

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

Carbon Dioxide Induced Changes in Cerebral Blood Flow and Flow Velocity: Role of Cerebrovascular Resistance and Effective Cerebral Perfusion Pressure

Effect of infusion tests on the dynamical properties of intracranial pressure in hydrocephalus

Analysis of Normal High-Frequency Intracranial Pressure Values and Treatment Threshold in Neurocritical Care Patients

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