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Background: Head elevation is recommended as a tier zero measure to decrease high intracranial pressure (ICP) in neurocritical patients. However, its quantitative effects on cerebral perfusion pressure (CPP), jugular bulb oxygen saturation (SjvO2), brain tissue partial pressure of oxygen (PbtO2), and arteriovenous difference of oxygen (AVDO2) are uncertain. Our objective was to evaluate the effects of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2 among patients with acute brain injury. Methods: We conducted a systematic review and meta-analysis on PubMed, Scopus, and Cochrane Library of studies comparing the effects of different degrees of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2. Results: A total of 25 articles were included in the systematic review. Of these, 16 provided quantitative data regarding outcomes of interest and underwent meta-analyses. The mean ICP of patients with acute brain injury was lower in group with 30° of head elevation than in the supine position group (mean difference [MD] − 5.58 mm Hg; 95% confidence interval [CI] − 6.74 to − 4.41 mm Hg; p < 0.00001). The only comparison in which a greater degree of head elevation did not significantly reduce the ICP was 45° vs. 30°. The mean CPP remained similar between 30° of head elevation and supine position (MD − 2.48 mm Hg; 95% CI − 5.69 to 0.73 mm Hg; p = 0.13). Similar findings were observed in all other comparisons. The mean SjvO2 was similar between the 30° of head elevation and supine position groups (MD 0.32%; 95% CI − 1.67% to 2.32%; p = 0.75), as was the mean PbtO2 (MD − 1.50 mm Hg; 95% CI − 4.62 to 1.62 mm Hg; p = 0.36), and the mean AVDO2 (MD 0.06 µmol/L; 95% CI − 0.20 to 0.32 µmol/L; p = 0.65).The mean ICP of patients with traumatic brain injury was also lower with 30° of head elevation when compared to the supine position. There was no difference in the mean values of mean arterial pressure, CPP, SjvO2, and PbtO2 between these groups. Conclusions: Increasing degrees of head elevation were associated, in general, with a lower ICP, whereas CPP and brain oxygenation parameters remained unchanged. The severe traumatic brain injury subanalysis found similar results. [ABSTRACT FROM AUTHOR]

Background: Numerous trials have addressed intracranial pressure (ICP) management in neurocritical care. However, identifying its harmful thresholds and controlling ICP remain challenging in terms of improving outcomes. Evidence suggests that an individualized approach is necessary for establishing tolerance limits for ICP, incorporating factors such as ICP waveform (ICPW) or pulse morphology along with additional data provided by other invasive (e.g., brain oximetry) and noninvasive monitoring (NIM) methods (e.g., transcranial Doppler, optic nerve sheath diameter ultrasound, and pupillometry). This study aims to assess current ICP monitoring practices among experienced clinicians and explore whether guidelines should incorporate ancillary parameters from NIM and ICPW in future updates. Methods: We conducted a survey among experienced professionals involved in researching and managing patients with severe injury across low-middle-income countries (LMICs) and high-income countries (HICs). We sought their insights on ICP monitoring, particularly focusing on the impact of NIM and ICPW in various clinical scenarios. Results: From October to December 2023, 109 professionals from the Americas and Europe participated in the survey, evenly distributed between LMIC and HIC. When ICP ranged from 22 to 25 mm Hg, 62.3% of respondents were open to considering additional information, such as ICPW and other monitoring techniques, before adjusting therapy intensity levels. Moreover, 77% of respondents were inclined to reassess patients with ICP in the 18–22 mm Hg range, potentially escalating therapy intensity levels with the support of ICPW and NIM. Differences emerged between LMIC and HIC participants, with more LMIC respondents preferring arterial blood pressure transducer leveling at the heart and endorsing the use of NIM techniques and ICPW as ancillary information. Conclusions: Experienced clinicians tend to personalize ICP management, emphasizing the importance of considering various monitoring techniques. ICPW and noninvasive techniques, particularly in LMIC settings, warrant further exploration and could potentially enhance individualized patient care. The study suggests updating guidelines to include these additional components for a more personalized approach to ICP management. [ABSTRACT FROM AUTHOR]

Background: Cerebral perfusion pressure (CPP) is an important target in aneurysmal subarachnoid hemorrhage (aSAH), but it does not take into account autoregulatory disturbances. The pressure reactivity index (PRx) and the CPP with the optimal PRx (CPPopt) are new variables that may capture these pathomechanisms. In this study, we investigated the effect on the outcome of certain combinations of CPP or ΔCPPopt (actual CPP-CPPopt) with the concurrent autoregulatory status (PRx) after aSAH. Methods: This observational study included 432 aSAH patients, treated in the neurointensive care unit, at Uppsala University Hospital, Sweden. Functional outcome (GOS-E) was assessed 1-year postictus. Heatmaps of the percentage of good monitoring time (%GMT) of PRx/CPP and PRx/ΔCPPopt combinations in relation to GOS-E were created to visualize the association between these variables and outcome. Results: In the heatmap of the %GMT of PRx/CPP, the combination of lower CPP with higher PRx values was more strongly associated with lower GOS-E. The tolerance for lower CPP values increased with lower PRx values until a threshold of −0.50. However, for decreasing PRx below −0.50, there was a gradual reduction in the tolerance for lower CPP. In the heatmap of the %GMT of PRx/ΔCPPopt, the combination of negative ΔCPPopt with higher PRx values was strongly associated with lower GOS-E. In particular, negative ΔCPPopt together with PRx above +0.50 correlated with worse outcomes. In addition, there was a transition toward an unfavorable outcome when PRx went below −0.50, particularly if ΔCPPopt was negative. Conclusions: The PRx levels influenced the association between CPP/ΔCPPopt and outcome. Thus, this variable could be used to individualize a safe CPP-/ΔCPPopt-range. [ABSTRACT FROM AUTHOR]

Background: Patients with traumatic brain injury (TBI) with large contusions make up a specific TBI subtype. Because of the risk of brain edema worsening, elevated cerebral perfusion pressure (CPP) may be particularly dangerous. The pressure reactivity index (PRx) and optimal cerebral perfusion pressure (CPPopt) are new promising perfusion targets based on cerebral autoregulation, but they reflect the global brain state and may be less valid in patients with predominant focal lesions. In this study, we aimed to investigate if patients with TBI with significant contusions exhibited a different association between PRx, CPP, and CPPopt in relation to functional outcome compared to those with small/no contusions. Methods: This observational study included 385 patients with moderate to severe TBI treated at a neurointensive care unit in Uppsala, Sweden. The patients were classified into two groups: (1) significant contusions (> 10 mL) and (2) small/no contusions (but with extra-axial or diffuse injuries). The percentage of good monitoring time (%GMT) with intracranial pressure > 20 mm Hg; PRx > 0.30; CPP < 60 mm Hg, within 60–70 mm Hg, or > 70 mm Hg; and ΔCPPopt less than − 5 mm Hg, ± 5 mm Hg, or > 5 mm Hg was calculated. Outcome (Glasgow Outcome Scale-Extended) was assessed after 6 months. Results: Among the 120 (31%) patients with significant contusions, a lower %GMT with CPP between 60 and 70 mm Hg was independently associated with unfavorable outcome. The %GMTs with PRx and ΔCPPopt ± 5 mm Hg were not independently associated with outcome. Among the 265 (69%) patients with small/no contusions, a higher %GMT of PRx > 0.30 and a lower %GMT of ΔCPPopt ± 5 mm Hg were independently associated with unfavorable outcome. Conclusions: In patients with TBI with significant contusions, CPP within 60–70 mm Hg may improve outcome. PRx and CPPopt, which reflect global cerebral pressure autoregulation, may be useful in patients with TBI without significant focal brain lesions but seem less valid for those with large contusions. However, this was an observational, hypothesis-generating study; our findings need to be validated in prospective studies before translating them into clinical practice. [ABSTRACT FROM AUTHOR]

Background: Neuromonitoring devices are often used in traumatic brain injury. The objective of this report is to raise awareness concerning variations in optimal cerebral perfusion pressure (CPPopt) determination using exploratory information provided by two neuromonitoring monitors that are part of research programs (Moberg CNS Monitor and RAUMED NeuroSmart LogO). Methods: We connected both monitors simultaneously to a parenchymal intracranial pressure catheter and recorded the pressure reactivity index (PRx) and the derived CPPopt estimates for a patient with a severe traumatic brain injury. These estimates were available at the bedside and were updated at each minute. Results: Using the Bland and Altman method, we found a mean variation of − 3.8 (95% confidence internal from − 8.5 to 0.9) mm Hg between the CPPopt estimates provided by the two monitors (limits of agreement from − 26.6 to 19.1 mm Hg). The PRx and CPPopt trends provided by the two monitors were similar over time, but CPPopt trends differed when PRx values were around zero. Also, almost half of the CPPopt estimates differed by more than 10 mm Hg. Conclusions: These wide variations recorded in the same patient are worrisome and reiterate the importance of understanding and standardizing the methodology and algorithms behind commercial neuromonitoring devices prior to incorporating them in clinical use. [ABSTRACT FROM AUTHOR]

Background: The Brain Oxygen Optimization in Severe Traumatic Brain Injury Phase II randomized controlled trial used a tier-based management protocol based on brain tissue oxygen (PbtO2) and intracranial pressure (ICP) monitoring to reduce brain tissue hypoxia after severe traumatic brain injury. We performed a secondary analysis to explore the relationship between brain tissue hypoxia, blood pressure (BP), and interventions to improve cerebral perfusion pressure (CPP). We hypothesized that BP management below the lower limit of autoregulation would lead to cerebral hypoperfusion and brain tissue hypoxia that could be improved with hemodynamic augmentation. Methods: Of the 119 patients enrolled in the Brain Oxygen Optimization in Severe Traumatic Brain Injury Phase II trial, 55 patients had simultaneous recordings of arterial BP, ICP, and PbtO2. Autoregulatory function was measured by interrogating changes in ICP and PbtO2 in response to fluctuations in CPP using time-correlation analysis. The resulting autoregulatory indices (pressure reactivity index and oxygen reactivity index) were used to identify the "optimal" CPP and limits of autoregulation for each patient. Autoregulatory function and percent time with CPP outside personalized limits of autoregulation were calculated before, during, and after all interventions directed to optimize CPP. Results: Individualized limits of autoregulation were computed in 55 patients (mean age 38 years, mean monitoring time 92 h). We identified 35 episodes of brain tissue hypoxia (PbtO2 < 20 mm Hg) treated with CPP augmentation. Following each intervention, mean CPP increased from 73 ± 14 mm Hg to 79 ± 17 mm Hg (p = 0.15), and mean PbtO2 improved from 18.4 ± 5.6 mm Hg to 21.9 ± 5.6 mm Hg (p = 0.01), whereas autoregulatory function trended toward improvement (oxygen reactivity index 0.42 vs. 0.37, p = 0.14; pressure reactivity index 0.25 vs. 0.21, p = 0.2). Although optimal CPP and limits remained relatively unchanged, there was a significant decrease in the percent time with CPP below the lower limit of autoregulation in the 60 min after compared with before an intervention (11% vs. 23%, p = 0.05). Conclusions: Our analysis suggests that brain tissue hypoxia is associated with cerebral hypoperfusion characterized by increased time with CPP below the lower limit of autoregulation. Interventions to increase CPP appear to improve autoregulation. Further studies are needed to validate the importance of autoregulation as a modifiable variable with the potential to improve outcomes. [ABSTRACT FROM AUTHOR]

To validate the intracranial pressure (ICP) dose-response visualization plot for the first time in a novel prospectively collected pediatric traumatic brain injury (pTBI) data set from the multi-center, multi-national KidsBrainIT consortium. Prospectively collected minute-by-minute ICP and mean arterial blood pressure time series of 104 pTBI patients were categorized in ICP intensity-duration episodes. These episodes were correlated with the 6-month Glasgow Outcome Score (GOS) and displayed in a color-coded ICP dose-response plot. The influence of cerebrovascular reactivity and cerebral perfusion pressure (CPP) were investigated. The generated ICP dose-response plot on the novel data set was similar to the previously published pediatric plot. This study confirmed that higher ICP episodes were tolerated for a shorter duration of time, with an approximately exponential decay curve delineating the positive and negative association zones. ICP above 20 mm Hg for any duration in time was associated with poor outcome in our patients. Cerebrovascular reactivity state did not influence their respective transition curves above 10 mm Hg ICP. CPP below 50 mm Hg was not tolerated, regardless of ICP and duration, and was associated with worse outcome. The ICP dose-response plot was reproduced in a novel and independent pTBI data set. ICP above 20 mm Hg and CPP below 50 mm Hg for any duration in time were associated with worse outcome. This highlighted a pressing need to reduce pediatric ICP therapeutic thresholds used at the bedside. [ABSTRACT FROM AUTHOR]

This article explores the importance of optimizing brain tissue oxygenation after traumatic brain injury (TBI) to prevent further damage and improve outcomes. It discusses the impact of variables such as blood pressure, oxygen levels, and metabolic demands on cerebral blood flow and tissue oxygenation. The article emphasizes the role of cerebral autoregulation in maintaining blood flow and suggests that monitoring brain tissue oxygenation could be beneficial in TBI management. However, the widespread adoption of this approach by trauma centers is limited. A study by Kunapaisal et al. examines the relationship between blood pressure augmentation, cerebral autoregulation, and brain tissue oxygenation in severe TBI patients. The study identifies individual differences in blood flow response and variability in brain tissue oxygenation after blood pressure augmentation. It suggests that traditional clinical factors may not be as effective in predicting cerebral hypoxia compared to multimodal monitoring techniques. The study raises questions about identifying the patient population that would benefit from autoregulation measurement and the need for further research in this area. The authors of the text discuss the timing and potential benefits of mean arterial pressure (MAP) augmentation in TBI patients. They acknowledge the challenges of comparing results over a large time range due to the evolving nature of brain injury. The authors also highlight missing critical values in the data analysis and express concerns about confounding factors. They propose that incorporating multimodal neuromonitoring and direct measurements can improve blood flow and patient outcomes. The authors caution against indiscriminate MAP augmentation and stress [Extracted from the article]

Cerebral blood flow (CBF) autoregulation is the physiologic process whereby blood supply to the brain is kept constant over a range of cerebral perfusion pressures ensuring a constant supply of metabolic substrate. Clinical methods for monitoring CBF autoregulation were first developed for neurocritically ill patients and have been extended to surgical patients. These methods are based on measuring the relationship between cerebral perfusion pressure and surrogates of CBF or cerebral blood volume (CBV) at low frequencies (<0.05 Hz) of autoregulation using time or frequency domain analyses. Initially intracranial pressure monitoring or transcranial Doppler assessment of CBF velocity was utilised relative to changes in cerebral perfusion pressure or mean arterial pressure. A more clinically practical approach utilising filtered signals from near infrared spectroscopy monitors as an estimate of CBF has been validated. In contrast to the traditional teaching that 50 mm Hg is the autoregulation threshold, these investigations have found wide interindividual variability of the lower limit of autoregulation ranging from 40 to 90 mm Hg in adults and 20–55 mm Hg in children. Observational data have linked impaired CBF autoregulation metrics to adverse outcomes in patients with traumatic brain injury, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and in surgical patients. CBF autoregulation monitoring has been described in both cardiac and noncardiac surgery. Data from a single-centre randomised study in adults found that targeting arterial pressure during cardiopulmonary bypass to above the lower limit of autoregulation led to a reduction of postoperative delirium and improved memory 1 month after surgery compared with usual care. Together, the growing body of evidence suggests that monitoring CBF autoregulation provides prognostic information on eventual patient outcomes and offers potential for therapeutic intervention. For surgical patients, personalised blood pressure management based on CBF autoregulation data holds promise as a strategy to improve patient neurocognitive outcomes. [ABSTRACT FROM AUTHOR]

To assess whether monitoring brain tissue oxygen partial pressure (PbtO2) or employing intracranial pressure (ICP)/cerebral perfusion pressure (CCP)-guided management improves patient outcomes, including mortality, hospital length of stay (LOS), mean daily ICP and mean daily CCP during the intensive care unit(ICU)stay. We searched the Web of Science, EMBASE, PubMed, Cochrane Library, and MEDLINE databases until December 12, 2023. Prospective randomized controlled and cohort studies were included. A meta-analysis was performed for the primary outcome measure, mortality, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eleven studies with a total of 37,492 patients were included. The mortality in the group with PbtO2 was 29.0% (odds ratio: 0.73;95% confidence interval [CI]:0.56–0.96; P = 0.03; I = 55%), demonstrating a significant benefit. The overall hospital LOS was longer in the PbtO2 group than that in the ICP/CPP group (mean difference:2.03; 95% CI:1.03–3.02; P<0.0001; I = 39%). The mean daily ICP in the PbtO2 monitoring group was lower than that in the ICP/CPP group (mean difference:-1.93; 95% CI: -3.61 to -0.24; P = 0.03; I = 41%). Moreover, PbtO2 monitoring did not improve the mean daily CPP (mean difference:2.43; 95%CI: -1.39 to 6.25;P = 0.21; I = 56%).Compared with ICP/CPP monitoring, PbtO2 monitoring reduced the mortality and the mean daily ICP in patients with severe traumatic brain injury; however, no significant effect was noted on the mean daily CPP. In contrast, ICP/CPP monitoring alone was associated with a short hospital stay. [ABSTRACT FROM AUTHOR]

Current neurointensive care guidelines recommend intracranial pressure (ICP) and cerebral perfusion pressure (CPP) centered management for moderate-severe traumatic brain injury (TBI) because of their demonstrated associations with patient outcome. Cerebrovascular reactivity metrics, such as the pressure reactivity index (PRx), pulse amplitude index (PAx), and RAC index, have also demonstrated significant prognostic capabilities with regard to outcome. However, critical thresholds for cerebrovascular reactivity indices have only been identified in two studies conducted at the same center. In this study, we aim to determine the critical thresholds of these metrics by leveraging a unique multi-center database. The study included a total of 354 patients from the CAnadian High-Resolution TBI (CAHR-TBI) Research Collaborative. Based on 6-month Glasgow Outcome Scores, patients were dichotomized into alive versus dead and favorable versus unfavorable. Chi-square values were then computed for incrementally increasing values of each physiological parameter of interest against outcome. The values that generated the greatest chi-squares for each parameter were considered to be the thresholds with the greatest outcome discriminatory capacity. To confirm that the identified thresholds provide prognostic utility, univariate and multivariable logistical regression analyses were performed adjusting for the International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) variables. Through the chi-square analysis, a lower limit CPP threshold of 60 mm Hg and ICP thresholds of 18 mm Hg and 22 mm Hg were identified for both survival and favorable outcome predictions. For the cerebrovascular reactivity metrics, different thresholds were identified for the two outcome dichotomizations. For survival prediction, thresholds of 0.35, 0.25, and 0 were identified for PRx, PAx, and RAC, respectively. For favorable outcome prediction, thresholds of 0.325, 0.20, and 0.05 were found. Univariate logistical regression analysis demonstrated that the time spent above/below thresholds were associated with outcome. Further, multivariable logistical regression analysis found that percent time above/below the identified thresholds added additional variance to the IMPACT core model for predicting both survival and favorable outcome. In this study, we were able to validate the results of the previous two works as well as to reaffirm the ICP and CPP guidelines from the Brain Trauma Foundation (BTF) and the Seattle International Severe Traumatic Brain Injury Consensus Conference (SIBICC). [ABSTRACT FROM AUTHOR]

This article provides a comprehensive review and analysis of the significance of intracranial pressure (ICP) monitoring, including the discovery of pressure reactivity index, its measurement methods, advantages, and limitations, as well as the derived parameters of pressure reactivity index and its mechanism in affecting patient prognosis. The methods used to determine pressure reactivity index are classified into invasive and non-invasive approaches. The pressure reactivity index can aid in evaluating patient outcomes, calculating optimal brain perfusion values, and enhancing the tolerance of damaged brains. Furthermore, its derived parameters also perform well in assessing the prognosis of patients with head injury. This article details the progress of pressure reactivity index in head injury. [ABSTRACT FROM AUTHOR]

Background: Bolus administration of adrenaline during cardiopulmonary resuscitation (CPR) results in only short-term increases in systemic and cerebral perfusion pressure (CePP) with unclear effects on cerebral oxygenation. The aim of this study was to investigate the effects of bolus compared to continuous adrenaline administration on cerebral oxygenation in a porcine CPR model. Methods: After five minutes of cardiac arrest, mechanical CPR was performed for 15 min. Adrenaline (45 μg/kg) was administered either as a bolus every five minutes or continuously over the same period via an infusion pump. Main outcome parameter was brain tissue oxygen tension (PbtO2), secondary outcome parameters included mean arterial pressure (MAP), intracranial pressure (ICP), CePP and cerebral regional oxygen saturation (rSO2) as well as arterial and cerebral venous blood gases. Results: During CPR, mean MAP (45 ± 8 mmHg vs. 38 ± 8 mmHg; p = 0.0827), mean ICP (27 ± 7 mmHg vs. 20 ± 7 mmHg; p = 0.0653) and mean CePP (18 ± 8 mmHg vs. 18 ± 8 mmHg; p = 0.9008) were similar in the bolus and the continuous adrenaline group. Also, rSO2 (both 24 ± 6 mmHg; p = 0.9903) and cerebral venous oxygen saturation (18 ± 12% versus 27.5 ± 12%; p = 0.1596) did not differ. In contrast, relative PbtO2 reached higher values in the continuous group after five minutes of CPR and remained significantly higher than in the bolus group until the end of resuscitation. Conclusion: Continuous administration of adrenaline improved brain tissue oxygen tension compared with bolus administration during prolonged CPR.

The article explores the impact of physiological factors on patient outcomes in traumatic brain injury (TBI). It discusses the association between intracranial pressure, cerebral perfusion pressure, and pressure reactivity index with unfavorable outcomes in TBI patients. The study introduces the concept of a "physiologic insult dose" and suggests the potential use of multiparameter visualizations in assessing autoregulation impairment. However, the study is limited by its single-center cohort and the need for further research to determine the practical application of these visualizations in clinical settings. [Extracted from the article]

Intracranial aneurysm is a common cerebrovascular disease with high mortality. Neurosurgical clipping for the treatment of intracranial aneurysms can easily lead to serious postoperative complications. Studies have shown that intraoperative monitoring of the degree of cerebral ischemia is extremely important to ensure the safety of operation and improve the prognosis of patients. Aim of this study was to probe the application value of combined monitoring of intraoperative neurophysiological monitoring (IONM)-intracranial pressure (ICP)-cerebral perfusion pressure (CPP) in craniotomy clipping of intracranial aneurysms. From January 2020 to December 2022, 126 patients in our hospital with intracranial aneurysms who underwent neurosurgical clipping were randomly divided into two groups. One group received IONM monitoring during neurosurgical clipping (control group, n=63), and the other group received IONM-ICP-CPP monitoring during neurosurgical clipping (monitoring group, n=63). The aneurysm clipping and new neurological deficits at 1 day after operation were compared between the two groups. Glasgow coma scale (GCS) score and national institutes of health stroke scale (NIHSS) score were compared before operation, at 1 day and 3 months after operation. Glasgow outcome scale (GOS) and modified Rankin scale (mRS) were compared at 3 months after operation. All aneurysms were clipped completely. Rate of new neurological deficit at 1 day after operation in monitoring group was 3.17 % (2/63), which was markedly lower than that in control group of 11.11 % (7/30) (P<0.05). At 1 day after operation, in monitoring group, GCS score was remarkably higher while NIHSS score was lower than that of control (P<0.05). At 3 months of postoperative follow-up, 5 cases were lost to follow-up in control group and 4 cases were lost in monitoring group. Excellent and good rate of GOS grading in control group was 89.65 % (52/58), and 93.22 % (55/58) in monitoring group. In addition, the excellent and good rate of mRS grading in control group was 91.38 % (53/58), and 94.92 % (56/58) in monitoring group, there was no remarkable difference in the excellent and good rate of GOS and mRS grading between the two groups at 3 months after operation (P>0.05). Combined monitoring of IONM-ICP-CPP can monitor the cerebral blood flow of patients in real time during neurosurgical clipping, according to the monitoring results, timely intervention measures can improve the consciousness state of patients in early postoperative period and reduce the occurrence of early postoperative neurological deficits. [ABSTRACT FROM AUTHOR]

Objective To study the normal reference values of intracranial pressure and cerebral perfusion pressure in children of different ages. Methods A retrospective study was conducted on the children with simple epidural hematoma who received hematoma removal and implantation for intracranial pressure monitoring in our department from January 2015 to June 2022.The intracranial pressure and arterial blood pressure of the children were monitored per hour after surgery, and the changes in intracranial pressure and cerebral perfusion pressure were analyzed based on time and age in different age groups.The intracranial pressure and cerebral perfusion pressure in stable period (72 h after surgery) were used as the relative normal reference values, and the 95% range of intracranial pressure and cerebral perfusion pressure were calculated statistically by percentile method as the reference range. Results A total of 207 children were included in this study, including 25 in the < 2-year-old group, 82 in the 2~6-year-old group and 100 in the >6-year-old group.Intracranial pressure in different age groups was increased rapidly after a short period of low level, while cerebral perfusion pressure experienced a short period of high level, and both reached a peak and a trough from 12 to 24 h after surgery, and gradually reached a stable range at 72 h after surgery.The range of intracranial pressure 72 h after surgery was 3.0~8.0 mmHg for the < 2-year-old group, 5.0~11.0 mmHg for the 2~6-year-old group, and 6.0~14.0 mmHg for the >6-year-old group.Cerebral perfusion pressure range was 50.9~68.7, 55.0~73.3, and 57.3~79.6 mmHg, respectively for the above 3 age groups. Conclusion The normal ranges of intracranial pressure and cerebral perfusion pressure are different in children of different ages, and we suggest increasing with age.

Abstract Background The primary aim was to explore the association of global cerebral physiological variables including intracranial pressure (ICP), cerebrovascular reactivity (PRx), cerebral perfusion pressure (CPP), and deviation from the PRx-based optimal CPP value (∆CPPopt; actual CPP-CPPopt) in relation to brain tissue oxygenation (pbtO2) in traumatic brain injury (TBI). Methods A total of 425 TBI patients with ICP- and pbtO2 monitoring for at least 12 h, who had been treated at the neurocritical care unit, Addenbrooke’s Hospital, Cambridge, UK, between 2002 and 2022 were included. Generalized additive models (GAMs) and linear mixed effect models were used to explore the association of ICP, PRx, CPP, and CPPopt in relation to pbtO2. PbtO2 20 mmHg, PRx > 0.30, CPP 20 mmHg, PRx > 0.30, CPP

Cerebral perfusion pressure (CPP) is the net pressure gradient that drives oxygen delivery to cerebral tissue. It is the difference between the mean arterial pressure (MAP) and the intracranial pressure (ICP). As CPP is a calculated value, MAP and ICP must be measured simultaneously. In research models, anesthetized and acute monitoring is incapable of providing a realistic picture of the relationship between ICP and MAP under physiological and/or pathophysiological conditions. For long-term monitoring of both pressures, the principle of telemetry can be used. The aim of this study was to map changes in CPP and spontaneous behavior using continuous pressure monitoring and video recording for 7 days under physiological conditions (group C - 8 intact rats) and under altered brain microenvironment induced by brain edema (group WI - 8 rats after water intoxication) and neuroprotection with methylprednisolone - MP (group WI+MP - 8 rats with MP 100 mg/kg b.w. applicated intraperitoneally during WI). The mean CPP values in all three groups were in the range of 40-60 mm Hg. For each group of rats, the percentage of time that the rats spent during the 7 days in movement pattern A (standard movement stereotype) or B (atypical movement) was defined. Even at very low CPP values, the standard movement stereotype (A) clearly dominated over the atypical movement (B) in all rats. There was no significant difference between control and experimental groups. Chronic CPP values with correlated behavioral type may possibly answer the question of whether there is a specific, universal, optimal CPP at all. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate if the absolute pressure reactivity index (PRx) value influenced the association between cerebral perfusion pressure (CPP) and outcome and if the optimal CPP (CPPopt) curve shape influenced the association between deviation from CPPopt and outcome in traumatic brain injury (TBI). We included 383 TBI patients treated at the neurointensive care in Uppsala between 2008 and 2018 with at least 24 h of CPP data. To determine the influence of absolute PRx values on the association between absolute CPP and outcome, the percentage of monitoring time for combinations of CPP and PRx were correlated with outcome (Extended Glasgow Outcome Scale [GOS-E]) in a heatmap. To determine the association between CPP and the relatively best PRx (CPPopt), the percentage of monitoring time of ΔCPPopt (actual CPP-CPPopt) ±5 mm Hg was analyzed in relation to GOS-E. To determine the association between CPP and the relatively best PRx within a certain absolute PRx range (curve shape), both the percentage of ΔCPPopt within the absolute limits of reactivity (PRx <0.00, < 0.15, etc.) and within certain confidence intervals of PRx-deterioration (+0.025, +0.05 etc.) from CPPopt were analyzed in relation to GOS-E. The heatmap of PRx and absolute CPP versus outcome indicated that the CPP range (55-75 mm Hg) associated with favorable outcome was wider when PRx was below 0, whereas the upper CPP-threshold decreased as PRx increased. CPPopt could be calculated during 53% of the monitoring time. Higher percentage of monitoring time with ΔCPPopt ±5 mm Hg, ΔCPPopt within the reactivity-thresholds (PRx <0.30), and ΔCPPopt within the PRx-confidence interval +0.025 were all independently associated with favorable outcome in separate logistic regressions. These regressions had similar area under receiver operating curve and were not superior to a similar regression when the CPPopt-target was replaced by the percentage of monitoring time within the traditional fixed CPP-targets 60 to 70 mm Hg. Individualized CPPopt-targets exhibited a comparable outcome association as traditional CPP targets and different definitions of the best CPPopt range based on the PRx value had a limited effect on the association between deviation from CPPopt and outcome. Since CPPopt could only be calculated during half of the time, an alternative approach would be to assess the absolute PRx to anticipate a safe CPP range. [ABSTRACT FROM AUTHOR]

Cerebral autoregulation (CA) is a physiological mechanism that maintains constant cerebral blood flow regardless of changes in cerebral perfusion pressure and prevents brain damage caused by hypoperfusion or hyperperfusion. In recent decades, researchers have investigated the range of systemic blood pressures and clinical management strategies over which cerebral vasculature modifies intracranial hemodynamics to maintain cerebral perfusion. However, proposed clinical interventions to optimize autoregulation status have not demonstrated clear clinical benefit. As future trials are designed, it is crucial to comprehend the underlying cause of our inability to produce robust clinical evidence supporting the concept of CA-targeted management. This article examines the technological advances in monitoring techniques and the accuracy of continuous assessment of autoregulation techniques used in intraoperative and intensive care settings today. It also examines how increasing knowledge of CA from recent clinical trials contributes to a greater understanding of secondary brain injury in many disease processes, despite the fact that the lack of robust evidence influencing outcomes has prevented the translation of CA-guided algorithms into clinical practice. [ABSTRACT FROM AUTHOR]

Background: Critical closing pressure (CrCP) and resistance-area product (RAP) have been conceived as compasses to optimize cerebral perfusion pressure (CPP) and monitor cerebrovascular resistance, respectively. However, for patients with acute brain injury (ABI), the impact of intracranial pressure (ICP) variability on these variables is poorly understood. The present study evaluates the effects of a controlled ICP variation on CrCP and RAP among patients with ABI. Methods: Consecutive neurocritical patients with ICP monitoring were included along with transcranial Doppler and invasive arterial blood pressure monitoring. Internal jugular veins compression was performed for 60 s for the elevation of intracranial blood volume and ICP. Patients were separated in groups according to previous intracranial hypertension severity, with either no skull opening (Sk1), neurosurgical mass lesions evacuation, or decompressive craniectomy (DC) (patients with DC [Sk3]). Results: Among 98 included patients, the correlation between change (Δ) in ICP and the corresponding ΔCrCP was strong (group Sk1 r = 0.643 [p = 0.0007], group with neurosurgical mass lesions evacuation r = 0.732 [p < 0.0001], and group Sk3 r = 0.580 [p = 0.003], respectively). Patients from group Sk3 presented a significantly higher ΔRAP (p = 0.005); however, for this group, a higher response in mean arterial pressure (change in mean arterial pressure p = 0.034) was observed. Exclusively, group Sk1 disclosed reduction in ICP before internal jugular veins compression withholding. Conclusions: This study elucidates that CrCP reliably changes in accordance with ICP, being useful to indicate ideal CPP in neurocritical settings. In the early days after DC, cerebrovascular resistance seems to remain elevated, despite exacerbated arterial blood pressure responses in efforts to maintain CPP stable. Patients with ABI with no need of surgical procedures appear to remain with more effective ICP compensatory mechanisms when compared with those who underwent neurosurgical interventions. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) describes parenchymal brain damage caused by external forces to the head. It has a massive personal and socioeconomic impact, as it is a disease with high morbidity and mortality. Both young and old people are affected, as a result of traffic or sports accidents as well as due to falls at home. The term TBI encompasses various clinical pictures, differing considerably in cause, prognosis and therapy. What they all have in common is the pathophysiological cascade that develops immediately after the initial trauma and which can persist for several days and weeks. In this phase, medical treatment, whether surgical or pharmacological, attempts to reduce the consequences of the primary damage. The aim is to maintain adequate cerebral perfusion pressure and to reduce intracranial pressure. [ABSTRACT FROM AUTHOR]

This article describes the anesthetic management of patients with traumatic brain injury (TBI) undergoing non-neurosurgery, primarily targeting intraoperative management for multiple-trauma surgery. The aim of this review is to promote the best clinical practice for patients with TBI in order to prevent secondary brain injury. Based on the current clinical guidelines and evidence, anesthetic selection and administration; maintenance of optimal cerebral perfusion pressure, oxygenation and ventilation; coagulation monitoring; glucose control; and temperature management are addressed. Neurological recovery, which is critical for improving the patient’s quality of life, is most important; therefore, future research needs to be focused on this aspect.

Purpose: The aim was to investigate the combined effect of insult intensity and duration, regarding intracranial pressure (ICP), pressure reactivity index (PRx), cerebral perfusion pressure (CPP), and optimal CPP (CPPopt), on clinical outcome in pediatric traumatic brain injury (TBI). Method: This observational study included 61 pediatric patients with severe TBI, treated at the Uppsala University Hospital, between 2007 and 2018, with at least 12 h of ICP data the first 10 days post-injury. ICP, PRx, CPP, and ∆CPPopt (actual CPP-CPPopt) insults were visualized as 2-dimensional plots to illustrate the combined effect of insult intensity and duration on neurological recovery. Results: This cohort was mostly adolescent pediatric TBI patients with a median age at 15 (interquartile range 12–16) years. For ICP, brief episodes (minutes) above 25 mmHg and slightly longer episodes (20 min) of ICP 20–25 mmHg correlated with unfavorable outcome. For PRx, brief episodes above 0.25 as well as slightly lower values (around 0) for longer periods of time (30 min) were associated with unfavorable outcome. For CPP, there was a transition from favorable to unfavorable outcome for CPP below 50 mmHg. There was no association between high CPP and outcome. For ∆CPPopt, there was a transition from favorable to unfavorable outcome when ∆CPPopt went below −10 mmHg. No association was found for positive ∆CPPopt values and outcome. Conclusions: This visualization method illustrated the combined effect of insult intensity and duration in relation to outcome in severe pediatric TBI, supporting previous notions to avoid high ICP and low CPP for longer episodes of time. In addition, higher PRx for longer episodes of time and CPP below CPPopt more than −10 mmHg were associated with worse outcome, indicating a potential role for autoregulatory-oriented management in pediatric TBI. [ABSTRACT FROM AUTHOR]

Background: The primary aim was to determine the association of intracranial hemorrhage lesion type, size, mass effect, and evolution with the clinical course during neurointensive care and long-term outcome after traumatic brain injury (TBI). Methods: In this observational, retrospective study, 385 TBI patients treated at the neurointensive care unit at Uppsala University Hospital, Sweden, were included. The lesion type, size, mass effect, and evolution (progression on the follow-up CT) were assessed and analyzed in relation to the percentage of secondary insults with intracranial pressure > 20 mmHg, cerebral perfusion pressure < 60 mmHg, and cerebral pressure autoregulatory status (PRx) and in relation to Glasgow Outcome Scale-Extended. Results: A larger epidural hematoma (p < 0.05) and acute subdural hematoma (p < 0.001) volume, greater midline shift (p < 0.001), and compressed basal cisterns (p < 0.001) correlated with craniotomy surgery. In multiple regressions, presence of traumatic subarachnoid hemorrhage (p < 0.001) and intracranial hemorrhage progression on the follow-up CT (p < 0.01) were associated with more intracranial pressure-insults above 20 mmHg. In similar regressions, obliterated basal cisterns (p < 0.001) were independently associated with higher PRx. In a multiple regression, greater acute subdural hematoma (p < 0.05) and contusion (p < 0.05) volume, presence of traumatic subarachnoid hemorrhage (p < 0.01), and obliterated basal cisterns (p < 0.01) were independently associated with a lower rate of favorable outcome. Conclusions: The intracranial lesion type, size, mass effect, and evolution were associated with the clinical course, cerebral pathophysiology, and outcome following TBI. Future efforts should integrate such granular data into more sophisticated machine learning models to aid the clinician to better anticipate emerging secondary insults and to predict clinical outcome. [ABSTRACT FROM AUTHOR]

Background: The primary aim was to explore the association of global cerebral physiological variables including intracranial pressure (ICP), cerebrovascular reactivity (PRx), cerebral perfusion pressure (CPP), and deviation from the PRx-based optimal CPP value (∆CPPopt; actual CPP-CPPopt) in relation to brain tissue oxygenation (pbtO2) in traumatic brain injury (TBI). Methods: A total of 425 TBI patients with ICP- and pbtO2 monitoring for at least 12 h, who had been treated at the neurocritical care unit, Addenbrooke's Hospital, Cambridge, UK, between 2002 and 2022 were included. Generalized additive models (GAMs) and linear mixed effect models were used to explore the association of ICP, PRx, CPP, and CPPopt in relation to pbtO2. PbtO2 < 20 mmHg, ICP > 20 mmHg, PRx > 0.30, CPP < 60 mmHg, and ∆CPPopt < − 5 mmHg were considered as cerebral insults. Results: PbtO2 < 20 mmHg occurred in median during 17% of the monitoring time and in less than 5% in combination with ICP > 20 mmHg, PRx > 0.30, CPP < 60 mmHg, or ∆CPPopt < − 5 mmHg. In GAM analyses, pbtO2 remained around 25 mmHg over a large range of ICP ([0;50] mmHg) and PRx [− 1;1], but deteriorated below 20 mmHg for extremely low CPP below 30 mmHg and ∆CPPopt below − 30 mmHg. In linear mixed effect models, ICP, CPP, PRx, and ∆CPPopt were significantly associated with pbtO2, but the fixed effects could only explain a very small extent of the pbtO2 variation. Conclusions: PbtO2 below 20 mmHg was relatively frequent and often occurred in the absence of disturbances in ICP, PRx, CPP, and ∆CPPopt. There were significant, but weak associations between the global cerebral physiological variables and pbtO2, suggesting that hypoxic pbtO2 is often a complex and independent pathophysiological event. Thus, other variables may be more crucial to explain pbtO2 and, likewise, pbtO2 may not be a suitable outcome measure to determine whether global cerebral blood flow optimization such as CPPopt therapy is successful. [ABSTRACT FROM AUTHOR]

Background: Prevention and treatment of haemodynamic instability and increased intracranial pressure (ICP) in patients with subarachnoid haemorrhage (SAH) is vital. This study aimed to evaluate the effects of protocolised cerebral perfusion pressure (CPP)-guided treatment on morbidity and functional outcome in patients admitted to the intensive care unit (ICU) with SAH. Methods: We performed a retrospective study comparing 37 patients who received standard haemodynamic treatment (control group) with 17 individuals (CPP-guided group) who were on the CPP-guided treatment aimed at maintaining CPP > 70 mmHg using both optimisations of ICP and mean arterial pressure (MAP). Results: MAP, cumulative crystalloid doses and fluid balance were similar in both groups. However, the incidence of delayed cerebral ischaemia was significantly lower in the CPP-guided group (14% vs. 64%, p < 0.01), and functional outcome as assessed by the Glasgow Outcome Scale at 30 days after SAH was improved (29.0% vs. 5.5%, p = 0.03). Conclusions: This preliminary analysis showed that implementing a CPP-guided treatment approach aimed at maintaining a CPP > 70 mmHg may reduce the occurrence of delayed cerebral ischaemia and improve functional outcomes in patients with SAH. This observation merits further prospective investigation of the use of CPP-guided treatment in patients with SAH. [ABSTRACT FROM AUTHOR]

The Japan Neurotrauma Data Bank is a source of epidemiological data for patients with severe traumatic brain injury (TBI) and is sponsored by the Japan Society of Neurotraumatology. In this report, we examined the changes in the treatment of severe TBI in Japan based on data of the Japan Neurotrauma Data Bank. Controlling and decreasing intracranial pressure (ICP) are the primary objective of severe TBI treatment. Brain-oriented whole-body control or neurocritical care, including control of cerebral perfusion pressure, respiration, and infusion, are also increasingly considered important because cerebral tissues require oxygenation to improve the outcomes of patients with severe TBI. The introduction of neurocritical care in Japan was delayed compared with that in Western countries. However, the rate of ICP monitoring increased from 28.0% in 2009 to 36.7% in 2015 and is currently likely to be higher. Neurocritical care has also become more common, but the functional prognosis of patients has not significantly improved in Japan. Changes in the background of patients with severe TBI suggest the need for improvement of acute-phase treatment for elderly patients. Appropriate social rehabilitation from the subacute to chronic phases and introduction of cellular therapeutics are also needed for patients with TBI.