Intracranial Pressure Measurement Research Articles

Focal brain oxygen, blood flow, and intracranial pressure measurements in relation to optimal cerebral perfusion pressure.

Different paradigms for neurocritical care of traumatic brain injury (TBI) have emerged in conjunction with advanced neuromonitoring technologies and derived metrics. The priority for optimizing these metrics is not currently clear. The goal of this study was to determine whether achieving cerebral perfusion pressure (CPPopt) also improves other metrics like brain oxygenation and brain blood flow. The authors performed a retrospective analysis of high-frequency data from patients with TBI who were treated at a single center and who had partial pressure of brain oxygen (PbtO2) measurements and/or brain blood flow measurements, while also undergoing intracranial pressure (ICP) monitoring. CPPopt was not calculated or targeted during patient care, but was retrospectively computed, as was the difference between the observed CPP and CPPopt. A total of 22 patients with ICP, PbtO2, and/or brain blood flow monitoring were included in the analysis, and 245.7 days of measurements obtained every second were analyzed including 6,748,866 PbtO2 measurements, 3,296,405 blood flow measurements, and 10,264,770 ICP measurements. The data obtained every second were averaged by minute for analysis. In summative data, PbtO2 measurements peaked near CPPopt and were not improved above CPPopt. Blood flow measurements remained stable near CPPopt, decreased below it, and increased when CPP exceeded CPPopt. ICP decreased linearly with CPP without a specific relationship with CPPopt. In an inverse analysis, the percentage of CPP values at CPPopt, although significantly higher on the favorable side of contemporary treatment thresholds of PbtO2, ICP, and blood flow, was not found to be strongly correlated with the mean values of the physiological measurements obtained every minute (r = 0.27, r = 0.11, and r = 0.47 for ICP, PbtO2, and blood flow, respectively; p < 0.0001). Although CPPopt was not targeted in the patients in this study, CPPopt was a physiologically significant value based on concurrent measurements of PbtO2 and blood flow. In summative data, achievement of CPPopt was associated with optimized PbtO2 and blood flow. Conversely, the correlation between achievement of CPPopt and the mean measurement value was not strong, strengthening the significance of CPPopt. In individual patients, achieving CPPopt is not always associated with optimal PbtO2 or blood flow. Further research should explore these relationships in treatment paradigms that specifically target CPPopt. These data do not support the premise that targeting and achieving CPPopt obviates the need for concurrent PbtO2 and blood flow monitoring. Although these data suggest that targeting CPPopt may be an appropriate initial treatment strategy, they do not provide evidence that CPPopt should be targeted with highest priority.

Sex differences in the diagnostic value of optic nerve sheath diameter for assessing intracranial pressure

The optic nerve sheath diameter (ONSD) can predict elevated intracranial pressure (ICP) but it is not known whether diagnostic characteristics differ between men and women. This observational study was performed at the Karolinska University Hospital in Sweden to assess sex differences in diagnostic accuracy for ONSD. We included 139 patients (65 women), unconscious and/or sedated, with invasive ICP monitoring. Commonly used ONSD derived measurements and associated ICP measurements were collected. Linear regression analyses were performed with ICP as dependent variable and ONSD as independent variable. Area under the receiver operator characteristics curve (AUROC) analyses were performed with a threshold for elevated ICP ≥ 20 mmHg. Analyses were stratified by sex. Optimal cut-offs and diagnostic characteristics were estimated. The ONSD was associated with ICP in women. The AUROCs in women ranged from 0.70 to 0.83. In men, the ONSD was not associated with ICP and none of the AUROCs were significantly larger than 0.5. This study suggests that ONSD is a useful predictor of ICP in women but may not be so in men. If this finding is verified in further studies, this would call for a re-evaluation of the usage and interpretation of ONSD to estimate ICP.

Reliability and performance of the IRRAflow® system for intracranial lavage and evacuation of hematomas-A technical note.

Intraventricular hemorrhage (IVH) is a severe condition with poor outcomes and high mortality. IRRAflow® (IRRAS AB) is a new technology introduced to accelerate IVH clearance by minimally invasive wash-out. The IRRAflow® system performs active and controlled intracranial irrigation and aspiration with physiological saline, while simultaneously monitoring and maintaining a stable intracranial pressure (ICP). We addressed important aspects of the device implementation and intracranial lavage. To allow versatile investigation of multiple device parameters, we designed an ex vivo lab setup. We evaluated 1) compatibility between the IRRAflow® catheter and the Silverline f10 bolt (Spiegelberg), 2) the physiological and hydrodynamic effects of varying the IRRAflow® settings, 3) the accuracy of the IRRAflow® injection volumes, and 4) the reliability of the internal ICP monitor of the IRRAflow®. The IRRAflow® catheter was not compatible with Silverline bolt fixation, which was associated with leakage and obstruction. Design space exploration of IRRAflow® settings revealed that appropriate settings included irrigation rate 20 ml/h with a drainage bag height at 0 cm, irrigation rate 90 ml/h with a drainage bag height at 19 cm and irrigation rate 180 ml/h with a drainage bag height at 29 cm. We found the injection volume performed by the IRRAflow® to be stable and reliable, while the internal ICP monitor was compromised in several ways. We observed a significant mean drift difference of 3.16 mmHg (variance 0.4, p = 0.05) over a 24-hour test period with a mean 24-hour drift of 3.66 mmHg (variance 0.28) in the pressures measured by the IRRAflow® compared to 0.5 mmHg (variance 1.12) in the Raumedic measured pressures. Bolting of the IRRAflow® catheter using the Medtronic Silverline® bolt is not recommendable. Increased irrigation rates are recommendable followed by a decrease in drainage bag level. ICP measurement using the IRRAflow® device was unreliable and should be accompanied by a control ICP monitor device in clinical settings.

Analysis of Cerebral Spinal Fluid Drainage and Intracranial Pressure Peaks in Patients with Subarachnoid Hemorrhage.

After aneurysmal subarachnoid hemorrhage (aSAH), elevated intracranial pressure (ICP) due to disrupted cerebrospinal fluid (CSF) dynamics is a critical concern. An external ventricular drainage (EVD) is commonly employed for management; however, optimal strategies remain debated. The randomized controlled Earlydrain trial showed that an additional prophylactic lumbar drainage (LD) after aneurysm treatment improves neurological outcome. We performed a post hoc investigation on the impact of drainage volumes and critical ICP values on patient outcomes after aSAH. Using raw patient data from Earlydrain, we analyzed CSF drainage amounts and ICP measurements in the first 8days after aSAH. Outcomes were the occurrence of secondary infarctions and the score on the modified Rankin scale after 6months, dichotomized in values of 0-2 as favorable and 3-6 as unfavorable. Repeated measurements were considered with generalized estimation equations. Earlydrain recruited 287 patients, of whom 221 received an EVD and 140 received an LD. Higher EVD volumes showed a trend to more secondary infarctions (p = 0.09), whereas higher LD volumes were associated with less secondary infarctions (p = 0.009). The mean total CSF drainage was 1052 ± 659mL and did not differ concerning infarction and neurological outcome. Maximum ICP values were higher in patients with poor outcomes but not related to drainage volumes via EVD. After adjustment for aSAH severity and total CSF drainage, higher LD volume was linked to favorable outcome (per 100mL: odds ratio 0.61 (95% confidence interval 0.39-0.95), p = 0.03), whereas higher EVD amounts were associated with unfavorable outcome (per 100mL: odds ratio 1.63 (95% confidence interval 1.05-2.54), p = 0.03). Findings indicate that effects of CSF drainage via EVD and LD differ. Higher amounts and higher proportions of LD volumes were associated with better outcomes, suggesting a potential quantity-dependent protective effect. Optimizing LD volume and mitigating ICP spikes may be a strategy to improve patient outcomes after aSAH. ClinicalTrials.gov identifier: NCT01258257.

Intraparenchymal near-infrared spectroscopy for detection of delayed cerebral ischemia in poor-grade aneurysmal subarachnoid hemorrhage

ObjectiveDetection of delayed cerebral ischemia (DCI) is challenging in comatose patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH). Brain tissue oxygen pressure (PbtO2) monitoring may allow early detection of its occurrence. Recently, a probe for combined measurement of intracranial pressure (ICP) and intraparenchymal near-infrared spectroscopy (NIRS) has become available. In this pilot study, the parameters PbtO2, Hboxy, Hbdeoxy, Hbtotal and rSO2 were measured in parallel and evaluated for their potential to detect perfusion deficits or cerebral infarction. MethodsIn patients undergoing multimodal neuromonitoring due to poor neurological condition after aSAH, Clark oxygen probes, microdialysis and NIRS-ICP probes were applied. DCI was suspected when the measured parameters in neuromonitoring deteriorated. Thus, perfusion CT scan was performed as follow up, and DCI was confirmed as perfusion deficit. Median values for PbtO2, Hboxy, Hbdeoxy, Hbtotal and rSO2 in patients with perfusion deficit (Tmax > 6 s in at least 1 vascular territory) and/or already demarked infarcts were compared in 24- and 48-hour time frames before imaging. ResultsData from 19 patients (14 University Hospital Zurich, 5 Charité Universitätsmedizin Berlin) were prospectively collected and analyzed. In patients with perfusion deficits, the median values for Hbtotal and Hboxy in both time frames were significantly lower. With perfusion deficits, the median values for Hboxy and Hbtotal in the 24 h time frame were 46,3 [39.6, 51.8] µmol/l (no perfusion deficits 53 [45.9, 55.4] µmol/l, p = 0.019) and 69,3 [61.9, 73.6] µmol/l (no perfusion deficits 74,6 [70.1, 79.6] µmol/l, p = 0.010), in the 48 h time frame 45,9 [39.4, 51.5] µmol/l (no perfusion deficits 52,9 [48.1, 55.1] µmol/l, p = 0.011) and 69,5 [62.4, 74.3] µmol/l (no perfusion deficits 75 [70,80] µmol/l, p = 0.008), respectively. In patients with perfusion deficits, PbtO2 showed no differences in both time frames. PbtO2 was significantly lower in patients with infarctions in both time frames. The median PbtO2 was 17,3 [8,25] mmHg (with no infarctions 29 [22.5, 36] mmHg, p = 0.006) in the 24 h time frame and 21,6 [11.1, 26.4] mmHg (with no infarctions 31 [22,35] mmHg, p = 0.042) in the 48 h time frame. In patients with infarctions, the median values of parameters measured by NIRS showed no significant differences. ConclusionsThe combined NIRS-ICP probe may be useful for early detection of cerebral perfusion deficits and impending DCI. Validation in larger patient collectives is needed.

Ultrasound-guided initial diagnosis and follow-up of pediatric idiopathic intracranial hypertension.

Idiopathic intracranial hypertension in children often presents with non-specific symptoms found in conditions such as hydrocephalus. For definite diagnosis, invasive intracranial pressure measurement is usually required. Ultrasound (US) of the optic nerve sheath diameter provides a non-invasive method to assess intracranial pressure. Transtemporal US allows imaging of the third ventricle and thus assessment for hydrocephalus. To investigate whether the combination of US optic nerve sheath and third ventricle diameter can be used as a screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure and exclude hydrocephalus as an underlying pathology. Further, to analyze whether both parameters can be used to monitor treatment outcome. We prospectively included 36 children with idiopathic intracranial hypertension and 32 controls. Using a 12-Mhz linear transducer and a 1-4-Mhz phased-array transducer, respectively, optic nerve sheath and third ventricle diameters were determined initially and during the course of treatment. In patients, the mean optic nerve sheath diameter was significantly larger (6.45±0.65 mm, controls: 4.96±0.32 mm) and the mean third ventricle diameter (1.69±0.65 mm, controls: 2.99±1.31 mm) was significantly smaller compared to the control group, P<0.001. Optimal cut-off values were 5.55 mm for the optic nerve sheath and 1.83 mm for the third ventricle diameter. The combined use of US optic nerve sheath and third ventricle diameter is an ideal non-invasive screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure while ruling out hydrocephalus. Treatment can effectively be monitored by repeated US, which also reliably indicates relapse.

Noninvasive Assessment of Intracranial Pressure: Deformability Index as an Adjunct to Optic Nerve Sheath Diameter to Increase Diagnostic Ability.

Today, invasive intracranial pressure (ICP) measurement remains the standard, but its invasiveness limits availability. Here, we evaluate a novel ultrasound-based optic nerve sheath parameter called the deformability index (DI) and its ability to assess ICP noninvasively. Furthermore, we ask whether combining DI with optic nerve sheath diameter (ONSD), a more established parameter, results in increased diagnostic ability, as compared to using ONSD alone. We prospectively included adult patients with traumatic brain injury with invasive ICP monitoring, which served as the reference measurement. Ultrasound images and videos of the optic nerve sheath were acquired. ONSD was measured at the bedside, whereas DI was calculated by semiautomated postprocessing of ultrasound videos. Correlations of ONSD and DI to ICP were explored, and a linear regression model combining ONSD and DI was compared to a linear regression model using ONSD alone. Ability of the noninvasive parameters to distinguish dichotomized ICP was evaluated using receiver operating characteristic curves, and a logistic regression model combining ONSD and DI was compared to a logistic regression model using ONSD alone. Forty-four ultrasound examinations were performed in 26 patients. Both DI (R = - 0.28; 95% confidence interval [CI] R < - 0.03; p = 0.03) and ONSD (R = 0.45; 95% CI R > 0.23; p < 0.01) correlated with ICP. When including both parameters in a combined model, the estimated correlation coefficient increased (R = 0.51; 95% CI R > 0.30; p < 0.01), compared to using ONSD alone, but the model improvement did not reach statistical significance (p = 0.09). Both DI (area under the curve [AUC] 0.69, 95% CI 0.53-0.83) and ONSD (AUC 0.72, 95% CI 0.56-0.86) displayed ability to distinguish ICP dichotomized at ICP ≥ 15mm Hg. When using both parameters in a combined model, AUC increased (0.80, 95% CI 0.63-0.90), and the model improvement was statistically significant (p = 0.02). Combining ONSD with DI holds the potential of increasing the ability of optic nerve sheath parameters in the noninvasive assessment of ICP, compared to using ONSD alone, and further study of DI is warranted.

Evaluating the utility of quantitative pupillometry in a neuro-critical care setting for the monitoring of intracranial pressure: A prospective cohort study

IntroductionAssessment of the pupillary light reflex (PLR) is key in intensive care monitoring of neurosurgical patients, particularly for monitoring intracranial pressure (ICP). Quantitative pupillometry using a handheld pupillometer is a reliable method for PLR assessment. However, many variables are derived from such devices. We therefore aimed to assess the performance of these variables at monitoring ICP. MethodsSedated patients admitted to neurocritical care in a tertiary neurosurgical centre with invasive ICP monitoring were included. Hourly measurement of ICP, subjective pupillometry (SP) using a pen torch device, and quantitative pupillometry (QP) using a handheld pupillometer were performed. Results561 paired ICP, SP and QP pupillary observations from nine patients were obtained (1122 total pupillary observations). SP and QP had a moderate concordance for pupillary size (κ=0.62). SP performed poorly at detecting pupillary size changes (sensitivity=24%). In 40 (3.6%) observations, SP failed to detect a pupillary response whereas QP did. Moderate correlations with ICP were detected for maximum constriction velocity (MCV), dilation velocity (DV), and percentage change in pupillary diameter (%C). Discriminatory ability at an ICP threshold of >22 mmHg was moderate for MCV (AUC=0.631), DV (AUC=0.616), %C (AUC=0.602), and pupillary maximum size (AUC=0.625). ConclusionQP is superior to SP at monitoring pupillary reactivity and changes to pupillary size. Although effect sizes were moderate to weak across assessed variables, our data indicates MCV and %C as the most sensitive variables for monitoring ICP. Further study is required to validate these findings and to establish normal range cut-offs for clinical use.

Reduction of cell surface attachment in experimental hydrocephalus using a novel ventricular catheter with modified tethered liquid perfluorocarbon.

Ventriculoperitoneal shunting, the most common treatment for the neurological disorder hydrocephalus, has a failure rate of up to 98% within 10 years of placement, mainly because of proximal obstruction of the ventricular catheter (VC). The authors developed a new VC design modified with tethered liquid perfluorocarbon (TLP) and tested it in a porcine model of hydrocephalus. In this study, they aimed to determine if their TLP VC design reduced cell surface attachment and consequent shunt obstruction in the pig model. TLP VCs were designed to reduce drainage hole obstruction using modified TLP and slightly enlarged draining holes, but their number and placement remained very similar to standard VCs. First, the authors tested the device in nonhydrocephalic rats to assess biocompatibility. After confirming safety, they implanted the VCs in hydrocephalic pigs. Hydrocephalus was induced by intracisternal kaolin injections in 30-day-old domestic juvenile pigs. Surgical implantation of the ventriculoperitoneal shunt (clinical control or TLP) was performed 10-14 days postinduction and maintained up to 30 days posttreatment. MRI was performed to measure ventricular volume before treatment and 10 and 30 days after treatment. Histological and immunohistochemical analyses of brain tissue and explanted VCs, intracranial pressure measurement, and clinical scoring were performed when the animals were euthanized. TLP VCs showed a similar surgical feel, kink resistance, and stiffness to control VCs. In rats (biocompatibility assessment), TLP VCs did not show brain inflammatory reactions after 30 or 60 days of implantation. In pigs, TLP VCs demonstrated increased survival time, improved clinical outcome scores, and significantly reduced total attached cells on the VCs compared with standard clinical control VCs. TLP VCs exhibited similar, but not worse, results related to ventriculomegaly, intracranial pressure, and the local tissue response around the cortical shunt track in pigs. TLP VCs may be a strong candidate to reduce proximal VC obstruction and improve hydrocephalus treatment.

The Relationship between Lumbar Puncture Opening Pressure and Retinal Nerve Fiber Layer Thickness in the Diagnosis of Idiopathic Intracranial Hypertension: Is a Lumbar Puncture Always Necessary?

Idiopathic intracranial hypertension (IIH), is characterized by elevated intracranial pressure (ICP) without an identified cause. Today, lumbar puncture (LP) is the most common method used for diagnosis by measuring cerebrospinal fluid (CSF) pressure to reflect intracranial pressure. This invasive examination has significant disadvantages, such as complications and negative experiences for patients. Therefore, noninvasive methods for ICP measurement are desired. Optical coherence tomography (OCT) is widely used for the diagnosis and follow-up of IIH patients as it reflects papilledema. The aim of this study is to investigate the relationship between CSF pressure and OCT parameters and the ability of OCT in the diagnostic approach. In our study, patients who were followed up with a diagnosis of IIH with complete neuro-ophthalmological examinations, including visual acuity (VA), visual field, and OCT imaging within 24 hours before lumbar puncture, were retrospectively evaluated. CSF pressure, visual acuity LogMAR, mean deviation of visual fields, retinal nerve fiber layer (RNFL) thickness measured by OCT, and treatment protocols were obtained from our hospital data system. A total of 42 eyes of 21 patients were enrolled in the study. A statistically significant positive and moderate correlation was found between CSF pressure values and average RNFL thickness (r=0.507; P=0.001). The same relationship was demonstrated in all 4 quadrants: inferior, superior, nasal, and temporal. Increased peripapillary RNFL thickness in optic nerve head OCT may be correlated with increased ICP in IIH patients. A larger number of patients are needed to better understand the correlation between OCT parameters and CSF pressure in patients with IIH.

Quantitative Pupillometry for Intracranial Pressure (ICP) Monitoring in Traumatic Brain Injury: A Scoping Review.

The neurological examination has remained key for the detection of worsening in neurocritical care patients, particularly after traumatic brain injury (TBI). New-onset, unreactive anisocoria frequently occurs in such situations, triggering aggressive diagnostic and therapeutic measures to address life-threatening elevations in intracranial pressure (ICP). As such, the field needs objective, unbiased, portable, and reliable methods for quickly assessing such pupillary changes. In this area, quantitative pupillometry (QP) proves promising, leveraging the analysis of different pupillary variables to indirectly estimate ICP. Thus, this scoping review seeks to describe the existing evidence for the use of QP in estimating ICP in adult patients with TBI as compared with invasive methods, which are considered the standard practice. This review was conducted in accordance with the Joanna Briggs Institute methodology for scoping reviews, with a main search of PubMed and EMBASE. The search was limited to studies of adult patients with TBI published in any language between 2012 and 2022. Eight studies were included for analysis, with the vast majority being prospective studies conducted in high-income countries. Among QP variables, serial rather than isolated measurements of neurologic pupillary index, constriction velocity, and maximal constriction velocity demonstrated the best correlation with invasive ICP measurement values, particularly in predicting refractory intracranial hypertension. Neurologic pupillary index and ICP also showed an inverse relationship when trends were simultaneously compared. As such, QP, when used repetitively, seems to be a promising tool for noninvasive ICP monitoring in patients with TBI, especially when used in conjunction with other clinical and neuromonitoring data.

Preoperative estimation of intracranial compliance in symptomatic children with Chiari malformation type 1: impact on outcome and risk of complications

BackgroundThe role of reduced intracranial compliance (ICC) in the outcome after foramen magnum decompression (FMD) was demonstrated in adults with Chiari malformation Type 1 (CMI). However, similar observations from children treated for CMI are missing.MethodsWe reviewed pediatric cases of CMI referred to FMD between 2006 and 2022. Children with clinical and/or radiological signs suggesting reduced ICC (Group A) underwent overnight measurements of the pulsatile intracranial pressure (ICP): mean ICP wave amplitude (MWA) served as a surrogate marker of ICC. Children with more typical symptoms of CMI (Group B) underwent FMD without preoperative ICC estimation. This study presents the clinical, radiological, and outcome differences between these groups.ResultsSixty-four children (mean age 11.1 ± 4.3 years) underwent FMD: In Group A (n = 30), the finding of reduced ICC as estimated from preoperative ICP measurement resulted in CSF diversion (ventriculoperitoneal shunt) before FMD in 11 children. Two patients required shunt due to complications after FMD (total shunt rate 43%). In Group B (n = 34) treated with FMD without preoperative ICC estimation, five children (15%) required shunting due to complications. In Group A, we found a significantly higher frequency of headache, nausea, fatigue, and dizziness. The outcome assessed by the modified Chicago Chiari Outcome Scale (mean follow-up 83 ± 57 months) was comparable between the groups, but the complication rate after FMD was significantly lower in Group A (7% vs. 32%; p = 0.011). The number of procedures (ICP measurement, FMD, shunt, re-do FMD, shunt revisions) was significantly higher in Group A (2.6 ± 0.9 vs. 1.5 ± 1.1 per patient; p < 0.001).ConclusionIn symptomatic children with CMI, the preoperative estimation of ICC from the overnight measurement of pulsatile ICP was more reliable for identifying those with reduced ICC than clinical and radiological assessment alone. When children with abnormally reduced ICC were identified and treated with CSF diversion before FMD, the complication rate was significantly reduced.

Optic Nerve Head and Retinal Changes in Idiopathic Intracranial Hypertension: Correlation with Short-Term Cerebrospinal Fluid Pressure Monitoring.

We aimed to assess the status of the optic nerve and retina by optical coherence tomography (OCT) in a group of patients with idiopathic intracranial hypertension (IIH) on the basis of dynamic changes in intracranial pressure. This observational and cross-sectional study included patients affected by idiopathic intracranial hypertension with papilledema (IIHWP) and patients with idiopathic intracranial hypertension without papilledema (IIHWOP). All participants underwent an OCT examination of the macula and optic nerve head. Parameters related to intracranial pressure, including cerebrospinal fluid (CSF) opening pressure (oCSFp), CSF mean pressure (mCSFp), and pulse wave amplitude (PWA), were included in the analysis. Out of the 22 subjects enlisted for the study, a total of 16 patients suggestive of IIH were finally enrolled. Papilledema was detected in nine subjects (56.2%) and seven patients were affected by IIHWOP (43.7%). The OCT examination showed a higher mean RNFL thickness in IIHWP patients in comparison to IIHWOP in both eyes (p < 0.05 and p < 0.01, respectively). Intracranial pressure (ICP) measurements showed that IIHWP had higher values of oCSFp, mCSFp, and PWA compared to IIHWOP (p = 0.0001, p = 0.0001, and p = 0.0001, respectively). In addition, ICP parameters significantly correlated with RNFL. Clinical parameters suggestive of idiopathic intracranial hypertension are associated with retina and optic nerve OCT parameters. OCT is a useful tool to detect these alterations in a non-invasive fashion.

Intraorbital pressure-volume characteristics in a piglet model: In vivo pilot study.

Intracranial pressure measurement is frequently used for diagnosis in neurocritical care but cannot always accurately predict neurological deterioration. Intracranial compliance plays a significant role in maintaining cerebral blood flow, cerebral perfusion pressure, and intracranial pressure. This study's objective was to investigate the feasibility of transferring external pressure into the eye orbit in a large-animal model while maintaining a clinically acceptable pressure gradient between intraorbital and external pressures. The experimental system comprised a specifically designed pressure applicator that can be placed and tightly fastened onto the eye. A pressure chamber made from thin, elastic, non-allergenic film was attached to the lower part of the applicator and placed in contact with the eyelid and surrounding tissues of piglets' eyeballs. External pressure was increased from 0 to 20 mmHg with steps of 1 mmHg, from 20 to 30 mmHg with steps of 2 mmHg, and from 30 to 50 mmHg with steps of 5 mmHg. An invasive pressure sensor was used to measure intraorbital pressure directly. An equation was derived from measured intraorbital and external pressures (intraorbital pressure = 0.82 × external pressure + 3.12) and demonstrated that external pressure can be linearly transferred to orbit tissues with a bias (systematic error) of 3.12 mmHg. This is close to the initial intraorbital pressure within the range of pressures tested. We determined the relationship between intraorbital compliance and externally applied pressure. Our findings indicate that intraorbital compliance can be controlled across a wide range of 1.55 to 0.15 ml/mmHg. We observed that external pressure transfer into the orbit can be achieved while maintaining a clinically acceptable pressure gradient between intraorbital and external pressures.

Parent perception of telemetric intracranial pressure monitoring in children - A qualitative case study

IntroductionTelemetric monitoring of intracranial pressure (ICP) in children with a complex cerebrospinal disorder might help parents distinguish acute and potential life-threatening symptoms of hydrocephalus from other illnesses. Research questionWhat is patient and parent perceptions of system utility of telemetric ICP monitoring, and how does a long-term telemetric implant influence daily life of both patients and their families? Material and methodsA qualitative case study design with a focus group interview including parents of children with a complex cerebrospinal fluid disorder and an implanted telemetric ICP sensor. ResultsThree parents participated. Based on thematic analysis, three themes were created: ‘Daily living with telemetric ICP monitoring’, ‘Parenting a child with a CSF disorder’, and ‘The healthy sibling’. The ICP sensor provided the parents with security and made them trust their intuition, while the possibility of home monitoring ensured stability for the entire family and had a calming effect on healthy siblings. Home monitoring was seen as the system's greatest advantages, whereas size, weight, and functionality of the external monitoring equipment were highlighted as disadvantages. Discussion and conclusionAll parents supported the telemetric ICP sensor as a valued tool in treatment guidance of their child and stated that advantages exceeded disadvantages. It was stated that the possibility of conducting ICP measurements at home reduced the need for acute hospital admissions, which consequently led to a more stable daily life for the entire family. Suggestions regarding technical improvements with focus on more compatible external monitoring equipment were raised by all parents included.

Non-Invasive Quantitative Approximation of Intracranial Pressure in Pediatric Idiopathic Intracranial Hypertension Based on Point-of-Care Ultrasound of the Optic Nerve Sheath Diameter.

To investigate whether ultrasound-based optic nerve sheath diameter (US-ONSD) is a reliable measure to follow up children with idiopathic intracranial hypertension (IIH). In addition, to analyze the inter- and intra-individual relationships between US-ONSD and intracranial pressure (ICP), and to investigate whether an individualized mathematical regression equation obtained from two paired US-ONSD/ICP values can be used to approximate ICP from US-ONSD values. 159 US examinations and 53 invasive ICP measures via lumbar puncture (LP) were performed in 28 children with IIH. US-ONSD was measured using a 12 Mhz linear transducer and compared to ICP values. In 15 children, a minimum of 2 paired US-ONSD/ICP determinations were performed, and repeated-measures correlation (rmcorr) and intra-individual correlations were analyzed. The cohort correlation between US-ONSD and ICP was moderate (r = 0.504, p < 0.01). Rmcorr (r = 0.91, p < 0.01) and intra-individual correlations (r = 0.956-1) of US-ONSD and ICP were excellent. A mathematical regression equation can be calculated from two paired US-ONSD/ICP values and applied to the individual patient to approximate ICP from US-ONSD. Related to excellent intra-individual correlations between US-ONSD and ICP, an individualized regression formula, created from two pairs of US-ONSD/ICP values, may be used to directly approximate ICP based on US-ONSD values. Hence, US-ONSD may become a non-invasive and reliable measure to control treatment efficacy in pediatric IIH.

Cerebral hemodynamic effects of head-up CPR in a porcine model

AimTo assess the hemodynamic effects of head elevation on cerebral perfusion during cardiopulmonary resuscitation (CPR) in a porcine model of cardiac arrest. MethodsVF was induced in eight 65 kg pigs that were treated with CPR after five minutes of no flow. Mean arterial pressure (MAP) was measured at the descending thoracic aorta. Internal carotid artery blood flow (CBF) was measured with an ultrasound probe. Cerebral perfusion pressure (CerPP) was calculated in two ways (CerPPICAP and CerPPreported) using the same intracranial pressure (ICP) measurement. CePPreported was calculated as MAP-ICP. CerPPICAP was calculated by using intracranial arterial pressure (ICAP) – ICP. The animals were switched between head up (HUP) and supine (SUP) CPR every five minutes for a total of twenty minutes of resuscitation. ResultsMAP and coronary perfusion pressure measurements were similar in both CPR positions (p = 0.36 and p = 0.1, respectively). ICP was significantly lower in the HUP CPR group (14.7 ± 1 mm Hg vs 26.9 ± 1 mm Hg, p < 0.001) as was ICAP (30.1 ± 2 mm Hg vs 42.6 ± 1 mmHg, p < 0.001). The proportional decrease in ICP and ICAP resulted in similar CerPPICAP comparing HUP and SUPCPR (p = 0.7). CBF was significantly lower during HUPCPR when compared to SUPCPR (58.5 ± 3 ml/min vs 78 ± 4 ml/min, p < 0.001). A higher CerPPreported was found during the HUP compared to SUP-CPR, when MAP was used (36.6 ± 2 mm Hg vs 23 ± 2 mm Hg, p < 0.001) without correcting for the hydrostatic pressure drop. ConclusionHUP did not affect cerebral perfusion pressure and it significantly decreased internal carotid blood flow.

Diagnostic accuracy of optic nerve sheath diameter on ultrasound for the detection of increased intracranial pressure in patients with traumatic brain injury: A systematic review and meta‑analysis.

The timely diagnosis and treatment of elevated intracranial pressure (ICP) reduces morbidity rates and prevents mortality. The aim of the present systematic review and meta-analysis was to determine the diagnostic accuracy of optic nerve sheath diameter (ONSD) vs. standard invasive ICP measurements in patients with traumatic brain injury (TBI). The PubMed, Embase, Web of Science and Cochrane Library databases were systematically searched for studies including adult patients with TBI with suspected elevated ICP, and the sonographic ONSD measurements were compared with those from a standard invasive method. The quality of the studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool by two independent authors. A bivariate random effects model was used to summarize the pooled sensitivity, specificity and diagnostic odds ratio (DOR). A total of eight prospective studies with 222 patients with TBI were included. The pooled sensitivity was 0.82 [95% confidence interval (CI), 0.75-0.88], the specificity was 0.82 (95% CI, 0.71-0.90) and the DOR was 17.75 (95% CI, 7.02-44.83) with partial evidence of heterogeneity. The accuracy of the area under the summary ROC was 0.87. An ultrasound-determined elevated ICP has reasonable performance indicators with high sensitivity and specificity in patients with TBI. As such, this method may be a useful complementary monitoring tool in acute care.

Aeromedical Transportation in an Area Intensive Care Unit: Experimental Study of Aircraft Pilots Undergoing Non-Invasive in-Flight Intracranial Pressure Measurement

Introduction: In certain emergency situations, a patient admitted to a hospital with fewer resources needs to be transferred quickly to a unit better prepared to deal with them. This is when the aeromedical transport service is needed. For this, the aircraft must be staffed by specialized health professionals and have a variety of resources to provide the best care for the patient. Objectives: 1) The general objective of this article was to analyze changes in intracranial pressure (ICP) in Brazilian Air Force pilots undergoing a level straight flight. 2) To help collect data for the development of a non-invasive sensor for monitoring ICP in flight. 3). To verify whether the equipment for measuring non-invasive Intracranial Pressure can be used in air ICUs. Materials and Methods: The work evaluated the presence of morphological changes in non-invasive ICP during level straight flight lasting 30 min among 10 (ten) pilots who volunteered for the collection. Results: It was observed that the ICP pulse waveform did not change during straight level flight, when compared to normal resting situations of an individual in a collection in a terrestrial environment, demonstrating the reliability of the equipment and the research. Final considerations: This study has helped to understand not only the need for rapid diagnosis of non-invasive ICP, but also the possible suitability of this equipment in aircraft prepared for rapid diagnosis and tratament.

Comparative Effectiveness of Intracranial Pressure Monitoring on 6-Month Outcomes of Critically Ill Patients With Traumatic Brain Injury

While the relationship between persistent elevations in intracranial pressure (ICP) and poorer outcomes is well established for patients with traumatic brain injury (TBI), there is no consensus on how ICP measurements should drive treatment choices, and the effectiveness of ICP monitoring remains unknown. To evaluate the effectiveness of ICP monitoring on short- and mid-term outcomes of patients with TBI. CREACTIVE was a prospective cohort study that started in March 2014 and lasted 5 years. More than 8000 patients with TBI were enrolled at 83 intensive care units (ICUs) from 7 countries who joined the CREACTIVE Consortium. Patients with TBI who met the Brain Trauma Foundation guidelines for ICP monitoring were selected for the current analyses, which were performed from January to November 2022. Patients who underwent ICP monitoring within 2 days of injury (exposure group) were propensity score-matched to patients who were not monitored or who underwent monitoring 2 days after the injury (control group). Functional disability at 6 months as indicated by Glasgow Outcome Scale-Extended (GOS-E) score. A total of 1448 patients from 43 ICUs in Italy and Hungary were eligible for analysis. Of the patients satisfying the ICP-monitoring guidelines, 503 (34.7%) underwent ICP monitoring (median [IQR] age: 45 years [29-61 years]; 392 males [77.9%], 111 females [22.1%]) and 945 were not monitored (median [IQR] age: 66 years [48-78 years]; 656 males [69.4%], 289 females [30.6%]). After matching to balance the variables, worse 6-month recovery was observed for monitored patients compared with nonmonitored patients (death/vegetative state: 39.2% vs 40.6%; severe disability: 33.2% vs 25.4%; moderate disability: 15.7% vs 14.9%; good recovery: 11.9% vs 19.1%, respectively; P = .005). Monitored patients received medical therapies significantly more frequently. In this cohort study, ICP monitoring was associated with poorer recovery and more frequent medical interventions with their relevant adverse effects. Optimizing the value of ICP monitoring for TBI requires further investigation on monitoring indications, clinical interventions, and management protocols.