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Pressure-volume curve for ICP. The pressure-volume curve has four 'zones': (1) baseline intracranial volume with good compensatory reserve and high compliance (blue); (2) gradual depletion of compensatory reserve as intracranial volume increases (yellow); (3) poor compensatory reserve and increased risk of cerebral ischemia and herniation (red); and (4) critically high ICP causing collapse of cerebral microvasculature and disturbed cerebrovascular reactivity (grey).
Source publication
Intracranial pressure (ICP) monitoring is a staple of neurocritical care. The most commonly used current methods of monitoring in the acute setting include fluid-based systems, implantable transducers and Doppler ultrasonography. It is well established that management of elevated ICP is critical for clinical outcomes. However, numerous studies show...
Contexts in source publication
Context 1
... compensatory reserve is finite and is dependent on the compliance of the system. When the reserve is depleted, small elevations in volume will lead to potentially dangerous sustained elevations in ICP (Figure 2). Alongside these mechanisms to attenuate changes in ICP, cerebrovascular autoregulation functions to maintain the necessary CPP in the face of ICP changes by way of altering cerebral arteriolar resistance. ...
Context 2
... guidelines for ICP management primarily use mean ICP as the main metric to guide therapy [16,49]. Given the shape of the intracranial pressure-volume curve (Figure 2), a reliance solely on mean ICP for clinical management fates the practice to be reactive rather than proactive [50]. Many have argued that this is the reason why ICP monitoring has not provided more clinical benefit than initially hoped [18]. ...
Citations
... Various invasive and noninvasive methods and devices are employed for ICP measurement [4]. Direct evaluation of IICP involves measuring ICP values in different anatomical spaces by placing devices into the intraventricular, intraparenchymal, epidural, subdural, and subarachnoid spaces [2,4]. ...
... Various invasive and noninvasive methods and devices are employed for ICP measurement [4]. Direct evaluation of IICP involves measuring ICP values in different anatomical spaces by placing devices into the intraventricular, intraparenchymal, epidural, subdural, and subarachnoid spaces [2,4]. However, this technique is invasive, requires neurosurgical expertise, and repeat ICP measurements present challenges. ...
Background: The objective of this investigation was to formulate a model for predicting intracranial pressure (ICP) by utilizing optic nerve sheath diameter (ONSD) during endovascular treatment for an aneurysmal subarachnoid hemorrhage (aSAH), incorporating explainable predictive modeling. Methods: ONSD measurements were conducted using a handheld ultrasonography device during the course of endovascular treatment (n = 126, mean age 58.82 ± 14.86 years, and female ratio 67.46%). The optimal ONSD threshold associated with an increased ICP was determined. Additionally, the association between ONSD and ICP was validated through the application of a linear regression machine learning model. The correlation between ICP and various factors was explored through the modeling. Results: With an ICP threshold set at 20 cmH2O, 82 patients manifested an increased ICP, with a corresponding ONSD of 0.545 ± 0.08 cm. Similarly, with an ICP threshold set at 25 cmH2O, 44 patients demonstrated an increased ICP, with a cutoff ONSD of 0.553 cm. Conclusions: We revealed a robust correlation between ICP and ONSD. ONSD exhibited a significant association and demonstrated potential as a predictor of ICP in patients with an ICP ≥ 25 cmH2O. The findings suggest its potential as a valuable index in clinical practice, proposing a reference value of ONSD for increased ICP in the institution.
... Intracranial pressure ICP is one of the most important methods in neurocritical care. Doctors need to determine the numeric value and changes of ICP, whether before or after an operation [1][2][3][4][5][6][7][8][9][10]. In recent years, the ICP waveform analysis has got more attention [10][11][12][13][14][15][16][17][18][19][20]. ...
... Doctors need to determine the numeric value and changes of ICP, whether before or after an operation [1][2][3][4][5][6][7][8][9][10]. In recent years, the ICP waveform analysis has got more attention [10][11][12][13][14][15][16][17][18][19][20]. Normal ICP waveforms have 3 peaks: P1 = percussion wave, which represents arterial pulsation; P2 = tidal wave, which represents intracranial compliance (ICC); and P3 = dicrotic wave, which represents aortic valve closure and venous pulsations. ...
In neurocritical care, the gold standard method is intracranial pressure (ICP) monitoring for the patient's lifesaving. Since it is an invasive method, it is desirable to use an alternative, noninvasive technique. The computerized real-time invasive cerebral blood flow (CBF) autoregulation (AR) monitoring calculates the status of CBF AR, called the pressure reactivity index (PRx). Studies documented that the electrical impedance of the head (Rheoencephalography – REG) can detect the status of CBF AR (REGx) and ICP noninvasively. We aimed to test REG to reflect ICP and CBF AR.
For nineteen healthy subjects we recorded bipolar bifrontal and bitemporal REG derivations and arm bioimpedance pulses with a 200 Hz sampling rate. The challenges were a 30-second breath-holding and head-down-tilt (HDT – Trendelenburg) position. Data were stored and processed offline. REG pulse wave morphology and REGx were calculated.
The most relevant finding was the significant morphological change of the REG pulse waveform (2 nd peak increase) during the HDT position. Breath-holding caused REG amplitude increase, but it was not significant. REGx in male and female group averages have similar trends during HDT by indicating the active status of CBF AR.
The morphological change of REG pulse wave during HDT position was identical to ICP waveform change during increased ICP, reflecting decreased intracranial compliance. A correlation study between ICP and REG was initiated in neurocritical care patients. The noninvasive REG monitoring would also be useful in space research as well as in military medicine during the transport of wounded service members as well as for fighter pilots to indicate the loss of CBF and consciousness.
... Существуют инвазивные и неинвазивные методики измерения ВЧД. В настоящее время «золотым стандартом» считаются инвазивные методики (введение катетера в мозговую ткань и/или желудочки ГМ), обладающие, однако, рядом таких недостатков, как инфекционные осложнения, внутрижелудочковые, субарахноидальные кровоизлияния, риск возникновения которых увеличивается на 5 % через пять дней после проведения [3,4]. ...
Modern methods of neuroimaging make it possible to develop approaches for assessing intracranial pressure as a replacement for the “gold standard” of invasive monitoring. Aim of the study was to investigate the possibility of using magnetic resonance (MR) characteristics to assess the increase in intracranial pressure in patients with secondary intracranial hypertension. Material and methods . Group 1 – 40 patients with brain tumors, group 2 – 15 patients with communicating hydrocephalus, control group – 36 individuals. The patients underwent MRI with measurement and evaluation of the optic nerve sheath diameter (ONSD), the optochiasmal cistern and the pituitary gland vertical sizes, and tortuosity of the ON. Patients of the 2nd group underwent a phase-contrast MRI with an assessment of the velocity and volumetric characteristics of blood and cerebrospinal fluid flows with the calculation of the intracranial compliance index (ICC). Using the FreeSurfer program, the brain volumes were estimated. Results and discussion . A statistically significant increase in ONSD was found in the groups of patients compared with the control group (by 24 %, p < 0.05), decrease in the vertical size of the pituitary gland and an increase in the vertical size of the optochiasmal cistern (p < 0.05), as well as ICC lowering in group 2 (by 1.7 times, p < 0.05). Tortuosity of ON in group 1 was observed more often than in other groups. A statistically significant positive correlation between ONSD and brain volumes in group 1 (r = 0.55, p < 0.05) and a negative correlation between brain volumes and ICC in group 2 (r = –0.86, p < 0.05) has been found. Conclusions . Based on the presented results, we believe that the combined use of qualitative and quantitative MRI criteria can expand the diagnostic capabilities of non-invasive assessment of increased intracranial pressure.
... Furthermore, in some patient populations, such as those with coagulopathies, liver failure, acute respiratory syndrome and pre-eclampsia, the risks associated with invasive ICP (ICPi) monitoring may preclude its routine use [5]. Additionally, challenges in accurate measurement of ICP may arise from asymmetry between hemispheres or compartments and progressive loss of precision over time [6]. It also may not be widely available in certain locations, particularly in rural areas or medical facilities with limited resources in developing countries [7]. ...
... Other noninvasive methods, such as Near Infrared Spectroscopy (NIRS), although promising, lack on evidences to the assess ICP and exclude IH [46]. Although several methods exist for non-invasive prediction of IH, all have some limitations, mostly being operator-dependent (transcranial Doppler and optic nerve sheath diameter) and not being able to show real-time changes in ICP (neuroimaging) [6,10,11]. In contrast, this noninvasive ICPW technique is highly suitable for either emergency or intensive care settings because of its readiness to acquire waveforms showing a higher NPV if compared with the methods described. ...
Intracranial hypertension (IH) is a life-threating condition especially for the brain injured patient. In such cases, an external ventricular drain (EVD) or an intraparenchymal bolt are the conventional gold standard for intracranial pressure (ICPi) monitoring. However, these techniques have several limitations. Therefore, identifying an ideal screening method for IH is important to avoid the unnecessary placement of ICPi and expedite its introduction in patients who require it. A potential screening tool is the ICP wave morphology (ICPW) which changes according to the intracranial volume-pressure curve. Specifically, the P2/P1 ratio of the ICPW has shown promise as a triage test to indicate normal ICP. In this study, we propose evaluating the noninvasive ICPW (nICPW-B4C sensor) as a screening method for ICPi monitoring in patients with moderate to high probability of IH. This is a retrospective analysis of a prospective, multicenter study that recruited adult patients requiring ICPi monitoring from both Federal University of São Paulo and University of São Paulo Medical School Hospitals. ICPi values and the nICPW parameters were obtained from both the invasive and the noninvasive methods simultaneously 5 min after the closure of the EVD drainage. ICP assessment was performed using a catheter inserted into the ventricle and connected to a pressure transducer and a drainage system. The B4C sensor was positioned on the patient's scalp without the need for trichotomy, surgical incision or trepanation, and the morphology of the ICP waves acquired through a strain sensor that can detect and monitor skull bone deformations caused by changes in ICP. All patients were monitored using this noninvasive system for at least 10 min per session. The area under the curve (AUC) was used to describe discriminatory power of the P2/ P1 ratio for IH, with emphasis in the Negative Predictive value (NPV), based on the Youden index, and the negative likelihood ratio [LR-]. Recruitment occurred from August 2017 to March 2020. A total of 69 patients fulfilled inclusion and exclusion criteria in the two centers and a total of 111 monitorizations were performed. The mean P2/P1 ratio value in the sample was 1.12. The mean P2/P1 value in the no IH population was 1.01 meanwhile in the IH population was 1.32 (p < 0.01). The best Youden index for the mean P2/P1 ratio was with a cutoff value of 1.13 showing a sensitivity of 93%, specificity of 60%, and a NPV of 97%, as well as an AUC of 0.83 to predict IH. With the 1.13 cutoff value for P2/P1 ratio, the LR-for IH was 0.11, corresponding to a strong performance in ruling out the condition (IH), with an approximate 45% reduction in condition probability after a negative test (ICPW). To conclude, the P2/P1 ratio of the noninvasive ICP waveform showed in this study a high Negative Predictive Value and Likelihood Ratio in different acute neurological conditions to rule out IH. As a result, this parameter may be beneficial in situations where invasive methods are not feasible or unavailable and to screen high-risk patients for potential invasive ICP monitoring.
... After the occurrence of cerebral hemorrhage, the spaceoccupying effect of hematoma and the edema of perihematoma increases the intracranial volume, and the ICP increases according to the law of intracranial volume-pressure curve after exceeding the co-compensatory regulation effect of cerebrospinal fluid and cerebral blood flow [5,[19][20][21][22]. ...
... cerebral vascular regulation function maintains a stable CBF by regulating cerebral artery resistance. Hypoperfusion and cerebral edema may occur when the CPP's automatic regulation range (50~100 mmHg) is exceeded [21]. After an ICH occurs, the effects of the damage caused by compression of the hematoma on the peripheral cerebral vessels decrease the local CBF, leading to peripheral cerebral tissue ischemia, hypoxia, and cerebral edema [26]. ...
Intracerebral hemorrhage (ICH) is the second major stroke type, with high incidence, high disability rate, and high mortality. At present, there is no effective and reliable treatment for ICH. As a result, most patients have a poor prognosis. Minimally invasive surgery (MIS) is the fastest treatment method to remove hematoma, which is characterized by less trauma and easy operation. Some studies have confirmed the safety of MIS, but there are still no reports showing that it can significantly improve the functional outcome of ICH patients. Intracranial pressure (ICP) monitoring is considered to be an important part of successful treatment in traumatic brain diseases. By monitoring ICP in real time, keeping stable ICP could help patients with craniocerebral injury get a good prognosis. In the course of MIS treatment of ICH patients, keeping ICP stable may also promote patient recovery. In this review, we will take ICP monitoring as the starting point for an in-depth discussion.
... Despite several limitations of the invasive method for monitoring ICP (ICPi) 5 , a noninvasive method (ICPni) that meets all the requirements to replace it is still not available 6 . Recently, either the association of noninvasive methods 7 or the creation of new ICPni monitoring techniques has renewed the interest in these technologies [8][9][10] . ...
Although the placement of an intraventricular catheter remains the gold standard method for the diagnosis of intracranial hypertension (ICH), the technique has several limitations including but not limited to its invasiveness. Current noninvasive methods, however, still lack robust evidence to support their clinical use. We aimed to estimate, as an exploratory hypothesis generating analysis, the discriminative power of four noninvasive methods to diagnose ICH. We prospectively collected data from adult intensive care unit (ICU) patients with subarachnoid hemorrhage (SAH), intraparenchymal hemorrhage (IPH), and ischemic stroke (IS) in whom invasive intracranial pressure (ICP) monitoring had been placed. Measures were simultaneously collected from the following noninvasive methods: optic nerve sheath diameter (ONSD), pulsatility index (PI) using transcranial Doppler (TCD), a 5-point visual scale designed for brain Computed Tomography (CT), and two parameters (time-to-peak [TTP] and P2/P1 ratio) of a noninvasive ICP wave morphology monitor (Brain4Care[B4c]). ICH was defined as a sustained ICP > 20 mmHg for at least 5 min. We studied 18 patients (SAH = 14; ICH = 3; IS = 1) on 60 occasions with a mean age of 52 ± 14.3 years. All methods were recorded simultaneously, except for the CT, which was performed within 24 h of the other methods. The median ICP was 13 [9.8-16.2] mmHg, and intracranial hypertension was present on 18 occasions (30%). Median values from the noninvasive techniques were ONSD 4.9 [4.40-5.41] mm, PI 1.22 [1.04-1.43], CT scale 3 points [IQR: 3.0], P2/P1 ratio 1.16 [1.09-1.23], and TTP 0.215 [0.193-0.237]. There was a significant statistical correlation between all the noninvasive techniques and invasive ICP (ONSD, r = 0.29; PI, r = 0.62; CT, r = 0.21; P2/P1 ratio, r = 0.35; TTP, r = 0.35, p < 0.001 for all comparisons). The area under the curve (AUC) to estimate intracranial hypertension was 0.69 [CIs = 0.62-0.78] for the ONSD, 0.75 [95% CIs 0.69-0.83] for the PI, 0.64 [95%Cis 0.59-069] for CT, 0.79 [95% CIs 0.72-0.93] for P2/P1 ratio, and 0.69 [95% CIs 0.60-0.74] for TTP. When the various techniques were combined, an AUC of 0.86 [0.76-0.93]) was obtained. The best pair of methods was the TCD and B4cth an AUC of 0.80 (0.72-0.88). Noninvasive technique measurements correlate with ICP and have an acceptable discrimination ability in diagnosing ICH. The multimodal combination of PI (TCD) and wave morphology monitor may improve the ability of the noninvasive methods to diagnose ICH. The observed variability in non-invasive ICP estimations underscores the need for comprehensive investigations to elucidate the optimal method-application alignment across distinct clinical scenarios. Abbreviations ICH Intracranial hypertension SAH Subarachnoid hemorrhage IPH Intraparenchymal hemorrhage IS Ischemic stroke ICPi Invasive intracranial pressure ONS Optic nerve sheath ONSD Optic nerve sheath diameter ONSUS Optic nerve sheath ultrasound OPEN
... Intracranial pressure monitoring assists in the diagnosis and treatment of various brain disorders, and continuous monitoring of ICP is recommended to avoid irreversible brain damage or deterioration of neurological function. [110,111] The limits of normal ICP depend on age and physical condition and are generally www.advancedsciencenews.com www.advhealthmat.de 5-15 mm Hg in adults. ...
Flexible sensors, as a significant component of flexible electronics, have attracted great interest the realms of human–computer interaction and health monitoring due to their high conformability, adjustable sensitivity, and excellent durability. In comparison to wearable sensor‐based in vitro health monitoring, the use of implantable flexible sensors (IFSs) for in vivo health monitoring offers more accurate and reliable vital sign information due to their ability to adapt and directly integrate with human tissue. IFSs show tremendous promise in the field of health monitoring, with unique advantages such as robust signal reading capabilities, lightweight design, flexibility, and biocompatibility. Herein, a review of IFSs for vital signs monitoring is detailly provided, highlighting the essential conditions for in vivo applications. As the prerequisites of IFSs, the stretchability and wireless self‐powered properties of the sensor are discussed, with a special attention paid to the sensing materials which can maintain prominent biosafety (i.e., biocompatibility, biodegradability, bioresorbability). Furthermore, the applications of IFSs monitoring various parts of the body are described in detail, with a summary in brain monitoring, eye monitoring, and blood monitoring. Finally, the challenges as well as opportunities in the development of next‐generation IFSs are presented.
... Intracranial pressure assessment and monitoring is critical in the management of several neurological and neurosurgical scenarios. Imbalances in central nervous system (CNS) fluid dynamics can result in increased intracranial pressure (IICP) requiring prompt identification and management which impacts clinical outcome [1]. But invasive techniques of intracranial pressure monitoring, including serial lumbar punctures and invasive intracranial pressure monitoring devices, have significant risks, namely postprocedural infection or hemorrhage [2][3][4]. ...
... 27,[30][31][32] However, the so-called Monro-Kellie doctrine, as it is known today, was not fully synthesized until the renowned American neurosurgeon, Harvey Cushing, compiled the various contributions into a succinct synopsis, which, to this day, serves as a fundamental concept in the field of neurosurgery. 27,33,34 The modern doctrine states that, with an intact skull and dura, the cranial compartment is of fixed volume and that the combined intracranial volume of brain parenchyma, blood, and CSF must remain constant, and therefore an increase in the volume of one component must be offset by a decrease in the volume of another component. 32,33 This doctrine lays out the fundamental principles that dictate ICP dynamics and is crucial for understanding the detrimental effects of ICH. ...
... 32,33 This doctrine lays out the fundamental principles that dictate ICP dynamics and is crucial for understanding the detrimental effects of ICH. 32,34 It should be noted that this concept does not apply to the infant given that the sutures of the infantile skull have not yet fused and thus allow for some degree of volumetric compliance. 35 Given that the contents of the cranium are relatively incompressible, stable ICP requires a volumetric equilibrium, where changes in the volume of one component are compensated for by changes in the volume of the other two components. ...
... 35 Given that the contents of the cranium are relatively incompressible, stable ICP requires a volumetric equilibrium, where changes in the volume of one component are compensated for by changes in the volume of the other two components. 24,34 This compensatory reserve is primarily provided by the brain's venous blood pool, which can be adjusted to maintain stable ICP. 34 The brain's CSF pool can also contribute to the maintenance of physiological ICP, however, to a lesser extent. ...
Since its introduction in the 1960s, intracranial pressure (ICP) monitoring has become an indispensable tool in neurocritical care practice and a key component of the management of moderate/severe traumatic brain injury (TBI). The primary utility of ICP monitoring is to guide therapeutic interventions aimed at maintaining physiological ICP and preventing intracranial hypertension. The rationale for such ICP maintenance is to prevent secondary brain injury arising from brain herniation and inadequate cerebral blood flow. There exists a large body of evidence indicating that elevated ICP is associated with mortality and that aggressive ICP control protocols improve outcomes in severe TBI patients. Therefore, current management guidelines recommend a cerebral perfusion pressure (CPP) target range of 60–70 mm Hg and an ICP threshold of >20 or >22 mm Hg, beyond which therapeutic intervention should be initiated. Though our ability to achieve these thresholds has drastically improved over the past decades, there has been little to no change in the mortality and morbidity associated with moderate-severe TBI. This is a result of the “one treatment fits all” dogma of current guideline-based care that fails to take individual phenotype into account. The way forward in moderate-severe TBI care is through the development of continuously derived individualized ICP thresholds. This narrative review covers the topic of ICP monitoring in TBI care, including historical context/achievements, current monitoring technologies and indications, treatment methods, associations with patient outcome and multi-modal cerebral physiology, present controversies surrounding treatment thresholds, and future perspectives on personalized approaches to ICP-directed therapy.
... The classical view of large-artery compliance is that it supports the dampening of strong cardiac ventricular ejections and assists in the reduction of the pulsatile nature of the flow into a more constant downstream flow at the site of the arterioles, thus supporting organ perfusion and ensuring consistent and manageable pulsatility to the downstream vessels [47]. In a similar physiological phenomenon, intracranial compliance has been described as essential to the compensatory mechanisms to maintain ICP stability and intracranial homeostasis [48]. ...
Introduction
Optimal shunt-based hydrocephalus treatments are heavily influenced by dynamic pressure behaviors between proximal and distal ends of shunt catheters. Posture-dependent craniospinal, arterial, venous, and abdominal dynamics thereby play an essential role.
Methods
An in-vivo ovine trial (n = 6) was conducted to evaluate communication between craniospinal, arterial, venous, and abdominal dynamics. Tilt-testing was performed between –13° and + 13° at 10-min intervals starting and ending at 0° prone position. Mean pressure, pulse pressure, and Pearson correlation (r) to the respective angle were calculated. Correlations are defined as strong: |r|≥ 0.7, mild: 0.3 <|r|< 0.7, and weak: |r|≤ 0.3. Transfer functions (TFs) between the arterial and adjacent compartments were derived.
Results
Strong correlations were observed between posture and: mean carotid/femoral arterial (r = − 0.97, r = − 0.87), intracranial, intrathecal (r = − 0.98, r = 0.94), jugular (r = − 0.95), abdominal cranial, dorsal, caudal, and intravesical pressure (r = − 0.83, r = 0.84, r = − 0.73, r = 0.99) while mildly positive correlation exists between tilt and central venous pressure (r = 0.65). Only dorsal abdominal pulse pressure yielded a significant correlation to tilt (r = 0.21). TFs followed general lowpass behaviors with resonant peaks at 4.2 ± 0.4 and 11.5 ± 1.5 Hz followed by a mean roll-off of − 15.9 ± 6.0 dB/decade.
Conclusions
Tilt-tests with multi-compartmental recordings help elucidate craniospinal, arterial, venous, and abdominal dynamics, which is essential to optimize shunt-based therapy. Results motivate hydrostatic influences on mean pressure, with all pressures correlating to posture, with little influence on pulse pressure. TF results quantify the craniospinal, arterial, venous, and abdominal compartments as compliant systems and help pave the road for better quantitative models of the interaction between the craniospinal and adjacent spaces.
