Erroneous intracranial pressure measurements from simultaneous pressure monitoring and ventricular drainage catheters

The objective of this report is to highlight the potential for false pressure measurements from systems that combine intracranial pressure (ICP) measurement and ventricular drainage. If the ports of the drain become blocked to the extent that they present a high resistance to cerebrospinal fluid flow, then a significant pressure gradient between the inside and outside of the catheter may be established. Thus, any intracatheter transducer will faithfully record a pressure much lower than true ICP. This holds true for catheter tip transducers when the transducer lies inside the catheter. In the absence of flow, however, pressures will equalize; therefore, accurate measurements may be taken if the drain is temporarily closed. We model this situation and provide simulations of expected measurements in such situations; these compare well to observed clinical readings.     

Clinical comparison of the Spiegelberg parenchymal transducer and ventricular fluid pressure

The Spiegelberg brain pressure catheter is a low cost implantable intracranial pressure measuring system which has the unique ability to perform regular automatic zeroing. A new version of the catheter has become available with a subdural bolt fixation to allow insertion of the device into the brain parenchyma. The accuracy of this system has been evaluated in comparison with a ventricular fluid pressure method in a series of patients to determine its accuracy and utility in the clinical environment. Hourly readings from the Spiegelberg system have been compared with those obtained using a standard pressure transducer connected to an external ventricular drain. Measurements continued while there was a clinical need for CSF drainage. Eleven patients were recruited to the study and data were recorded for periods ranging from 40 to 111 hours. A good agreement between the two systems was obtained. In 10 cases the mean difference was less than +/-1.5 mm Hg and the dynamic changes in value were contemporaneous. In one case an intracerebral haemorrhage developed around the tips of the Spiegelberg catheter and significant differences occurred between the two methods of measurement. In conclusion, the Spiegelberg parenchymal transducer provides an accurate measurement of intracranial pressure when compared with ventricular pressure. The transducer was found to be robust in the clinical environment and very popular with the nursing staff. Further studies may determine whether the complication rate of this system is comparable with other available devices.     

Recording methods of intracranial pressure. (author's transl)]

The physiopathology of intracranial pressure and its measuring techniques are briefly discussed. Such measurements may be achieved: 1) At lumbar level (measurement of cerebrospinal fluid): the main limitations of this method are due to impossibility of long term recording and the danger of "cerebral erniation* in patients with increased ICP. 2) At cranial level with: a) ventricular catheter connected to a pressure transducer: its limitations are due to difficulties in entering small and/or displaced ventricules in case of cerebral edema or expanding lesion, danger of infections, and catheter obstruction amongst others. b) pressure transducer in the extradural space connected with external recorder by electric wires: its limitations are due to frequent lack of parallelism with the dural surface and the variability of correlations between extra and intradural pressure; c) subdural pressure transducer; these appear the most reliable both from the literature and from the Authors personal experience. The Authors stress the importance of ICP monitoring in head injuries and after intracranial surgery (mostly for an early detection of complications due to cerebral edema or hemorrhages).     

经侧脑室引流管测压与有创颅内压监测的对比研究

目的探讨经侧脑室引流管测压进行实时颅内压（ICP）监测的准确性和安全性。 方法对福建医科大学附属第一医院神经外科自2016年1月至2018年6月收治的行脑室型有创ICP监测传感器置入术的28例患者,同时采用压力传感器连接侧脑室外引流管测量脑脊液传导压力（P1）,通过临床监测数据采集软件系统每分钟实时采集P1和同期监测的有创ICP数据,每频段连续采集30 min,分析和对比2组数据的一致性。同时对患者的临床特征、颅内感染和浅表手术切口感染、颅内再出血等进行分析。 结果28例患者共获得87个频段和2610对P1和ICP数值。有创ICP监测的平均值为（14.217±6.729）mmHg（1 mmHg=0.133 kPa）,引流管测压P1的平均值为（14.263±6.765）mmHg,ICP与P1的组内相关系数（ICC）为0.977（P<0.001）,具有较高的一致性。2组数据Band-Altman散点图显示P1与ICP的差值为（0.046±1.435）mmHg（95%CI：-2.767~2.859）。28例患者均未发生手术相关的颅内感染、浅表手术切口感染和愈合不良、颅内再出血等。 结论经侧脑室引流管连接压力传感器测压与有创ICP传感器监测所得到的ICP值具有良好的一致性,其准确性和安全性较高,可作为持续监测ICP的有效技术。     

Infratentorial intracranial pressure monitoring in neurosurgical intensive care unit

Monitoring intracranial pressure (ICP) is an important element of neurosurgical critical care that is used primarily as an indicator of adequate cerebral perfusion. Such monitoring is usually done with intraparenchymal, subdural or intraventricular pressure sensor connected to a pressure transducer system. In the past, multiple studies have shown that there are certain pressure gradients between various intracranial compartments, especially if there is some focal intracranial pathological process. Several clinical and laboratory studies measured ICP inside the posterior fossa by placing the sensor into the cisterna magna or the cerebellopontine angle. None of them, however, monitored direct intraparenchymal pressure in the posterior fossa. Such measurement may be a more sensitive way to assess focal swelling, ischemia and tissue perfusion in the posterior fossa structures. We simultaneously monitored supratentorial ICP using an external ventricular drain placed in the lateral ventricle and infratentorial ICP with an intraparenchymal sensor inserted into the cerebellum. We subsequently analyzed data from five patients with different posterior fossa pathology each of which had simultaneous supra- and infratentorial ICP recordings for up to five days. We found difference in ICP between the infratentorial and supratentorial compartments and this difference changed over time. In this article, we discuss feasibility and safety of simultaneous infra- and supratentorial ICP monitoring in patients with the posterior fossa pathology.     

Infratentorial intracranial pressure monitoring in neurosurgical intensive care unit

Abstract

Monitoring intracranial pressure (ICP) is an important element of neurosurgical critical care that is used primarily as an indicator of adequate cerebral perfusion. Such monitoring is usually done with intraparenchymal, subdural or intraventricular pressure sensor connected to a pressure transducer system. In the past, multiple studies have shown that there are certain pressure gradients between various intracranial compartments, especially if there is some focal intracranial pathological process. Several clinical and laboratory studies measured ICP inside the posterior fossa by placing the sensor into the cisterna magna or the cerebellopontine angle. None of them, however, monitored direct intraparenchymal pressure in the posterior fossa. Such measurement may be a more sensitive way to assess focal swelling, ischemia and tissue perfusion in the posterior fossa structures. We simultaneously monitored supratentorial ICP using an external ventricular drain placed in the lateral ventricle and infratentorial ICP with an intraparenchymal sensor inserted into the cerebellum. We subsequently analyzed data from five patents with different posterior fossa pathology each of which had simultaneous supra- and infratentorial ICP recordings for up to five days. We found difference in ICP between the infratentorial and supratentorial compartments and this difference changed over time. In this article, we discuss feasibility and safety of simultaneous infra- and supratentorial ICP monitoring in patients with the posterior fossa pathology.     

Intracranial pressure monitoring in children: comparison of external ventricular device with the fiberoptic system

Several intracranial pressure monitoring devices have been developed in the past several years. We have recently adopted the Camino fiberoptic device that permits subdural, intraparenchymal, and intraventricular monitoring. In this report we compare experiences in monitoring a group of pediatric patients with severe craniocerebral trauma and coma, grouped according to severity of Glasgow Coma Scale score. Patient age ranged from 2 to 16 years. Twelve patients were monitored by a ventricular catheter and 37, treated more recently, by a Camino fiberoptic device. The study demonstrated that the fiberoptic device and the ventricular catheter have the same accuracy and reliability. The fiberoptic method correlates very closely with the ventriculostomy method, but the pressure values are always 3±2 mmHg lower than those obtained with the conventional pressure transducer system, especially in more critically ill patients. This new technique is also easier to implant, safer to use, has minimal drift, and is minimally invasive, which particularly speaks for its use in pediatric patients.     

Cerebral Vascular Changes During Acute Intracranial Pressure Drop

Neurocritical Care - This study applied a new external ventricular catheter, which allows intracranial pressure (ICP) monitoring and cerebral spinal fluid (CSF) drainage simultaneously, to study...     

Risk factors and complications of intracranial pressure monitoring with a fiberoptic device

We prospectively investigated the complications associated with intraparenchymal intracranial pressure (ICP) monitoring using the Camino intracranial pressure device. A fiberoptic ICP monitoring transducer was implanted in 631 patients. About half of the patients (n = 303) also received an external ventricular drainage set (EVDS). The durations (mean ± SD) of ICP monitoring in patients without and with an EVDS were 6.5 ± 4.4 and 7.3 ± 5.1 days, respectively. Infection occurred in 6 patients with only an ICP transducer (6/328, 1.8%) and 24 patients with an EVDS also (24/303, 7.9%). The duration of monitoring had no effect on infection, whereas the use of an EVDS for more than 9 days increased infection risk by 5.11 times. Other complications included transducer disconnection (2.37%), epidural hematoma (0.47%), contusion (0.47%), defective probe (0.31%), broken transducer (0.31%), dislocation of the fixation screw (0.15%), and intraparenchymal hematoma (0.15%). In conclusion, intraparenchymal ICP monitoring systems can be safely used in patients who either have, or are at risk of developing, increased ICP.     

Measurement of intracranial pressure in children: a critical review of current methods

Assessment of intracranial pressure (ICP) is essential in the management of acute intracranial catastrophe to limit or actively reduce ICP. This article provides background information and reviews the current literature on methods of measuring ICP in children. Indications for ICP measurement are described for children with traumatic brain injury, shunt insertion or malfunction, arachnoid cyst, craniosynostosis, and prematurity. Various methods of ICP monitoring are detailed: non-invasive, indirect (lumbar puncture, visual-evoked potentials, fontanelle compression, and optic nerve sheath), and direct assessment (ventricular cannulation, and epidural, subdural, and intraparenchymal devices). Normal levels of ICP will depend on the age and position of the child during monitoring. This article provides clinical and research-based evidence in this area where there is currently limited guidance.     

The importance of valve alignment in determining the pressure/flow characteristics of differential pressure shunt valves with anti-gravity devices

Object: The proper functioning of shunt valves in vivo is dependent on many factors, including the valve itself, the anti-siphon device or ASD (if included), patency of inlet and outlet tubing, and location of the valve. One important, but sometimes overlooked, consideration in valve function is the valve location relative to the tip of the ventricular inlet catheter. As with any pressure measurement, the zero or reference position is an important concept. In the case of shunt valves, the position of the proximal inlet catheter tip is fixed and therefore serves as the reference point for all pressure measurements. This study was conducted to document the importance of this relationship for the pressure/flow characteristics of the shunt valve. Methods: We bench-tested differential pressure valves (with integral anti-gravity devices; AGDs) from three manufacturers. Valves were connected to an ”infinite” reservoir, and the starting head pressure for each was determined from product inserts. The inlet catheter tip was fixed at this position, and the valve body was moved in relation to the inlet catheter tip. Outflow rates were determined gravimetrically for positions varying between 4 cm above and 8 cm below the inlet catheter tip. Conclusions: All differential pressure valves utilized in this study that contained AGDs showed significant increases in outflow rate as the valve body was moved incrementally below the level of the inlet catheter tip. To allow functioning as a zero- hydrostatic pressure differential pressure valve, the AGD and the inlet catheter tip should be aligned at the same horizontal level. Received: 27 March 2000 Revised: 14 July 2000     

Non-invasive ICP monitoring in infants: the Rotterdam Teletransducer revisited

Measurement of intracranial pressure (ICP) is important in patients at risk of raised ICP, as in hydrocephalus. Ideally, it should be non-invasive, thus avoiding the risk of infection and other complications. Such is provided by measurement of ICP through the anterior fontanelle. There are several methods of measuring anterior fontanelle pressure (AFP); those most frequently used are based on the applanation principle. An evaluation of AFP measurement devices resulted in the choice of the Rotterdam Teletransducer (RTT) to be used in our study of children with hydrocephalus. The literature contains little information on the accuracy or validation of the AFP measurements using the RTT. Therefore, the physical qualities of the RTT were reassessed, using a specially developed calibration device. The results of this study demonstrate that membrane temperature does not have any effect on the measured pressure. The thermal stabilization time of the RTT was found to be 3 h after switching on . Insufficient thermal stabilization results in a pressure underestimation of up to 3 mmHg. Furthermore, a maximum inaccuracy of 2.6 mmHg, after calibration and readjustment of the transducer, was calculated. Validation of the equipment was achieved by simultaneous AFP/ICP measurements in hydrocephalic patients showing high correlations (r=0.96–0.98). The discusion suggests a measurement protocol as a means of increasing the reliability of RTT measurements.     

Accuracy of ultrasound-guided puncture of the ventricular system

Objects Puncture of the ventricular system as one of the most frequently performed operative procedures in neurosurgery is usually done in a freehand way without guiding devices. The objective of this study is to examine whether ultrasonic guidance is able to heighten the accuracy of ventricular tapping. Methods Real-time imaging via a single burr hole approach is achieved by aid of a bajonet-like shaped transducer with a footprint of 8x8 mm only (EUP-NS32, Hitachi Medical Systems). The needle is advanced towards the frontal horn along a displayed guideline. 51 punctures in 48 patients were performed with ultrasonic guidance and compared to 85 punctures in 67 patients without a guiding device. Conclusion The presented ultrasound method was not able to heighten the access rate of ventricular tapping, but it improved correct positioning of the catheter tip inside the frontal horn of the ventricular system significantly.     

Cerebral intraparenchymal pressure monitoring in non-traumatic coma: clinical evaluation of a new fibreoptic device

Initial reporting and validation of the Camino miniaturised fibreoptic cerebral intraparenchymal pressure monitoring device has indicated that this tip transducing system (a) allows direct measurement of brain tissue pressure, (b) has a rapid response rate to intracranial changes and (c) correlates well with intraventricular pressure. However, there are no specific reports of this form of monitoring during non-traumatic coma in children, or any evaluation of change in clinical practice when compared with experience of other forms of invasive intracranial pressure monitoring. Over a 5-year-period (1985-1989) on the General Paediatric Intensive Care Unit, 74 children with presumed raised intracranial pressure complicating non-traumatic coma have had invasive intracranial pressure monitoring with a variety of devices. An intraventricular catheter was used in 16 patients, a subdural catheter in 6 patients, a subarachnoid screw in 35 patients and a fibreoptic intraparenchymal catheter in 17 patients. In 1985 to 1986 our preferred technique was the subarachnoid screw (33/49 patients monitored). Between 1987 and 1989 we have mainly used the Camino fibreoptic intraparenchymal monitoring system (17/25 patients monitored). In the whole series there were no cases of acute haemorrhage related to monitoring and only one patient developed infection and in this child an intraventricular catheter was used. The experience with the fibreoptic system has been favourable and the technique for insertion does not require additional expertise in comparison with standard subarachnoid screw pressure monitoring. Therefore in young children with raised intracranial pressure complicating non-traumatic coma, cerebral fibreoptic intraparenchymal pressure monitoring should be used in preference to standard subarachnoid screw pressure monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)     

Third ventriculostomy through the lamina terminalis for intracranial pressure monitoring after aneurysm surgery: technical note

OBJECTIVE: A new ventriculostomy technique through the lamina terminalis is described. This technique is applied mainly during aneurysm surgery at the acute stage. METHOD: Thirteen patients were operated on intracranial aneurysms and, during the procedure, had the lamina terminalis fenestrated. A ventricular catheter was inserted into the third ventricule, left in place and connected to an external drainage system for further intracranial pressure (ICP) monitoring and/or cerebrospinal fluid (CSF) drainage. RESULTS: ICP readings and CSF drainage were obtained in all cases. No complication was recorded. CONCLUSION: Third ventriculostomy through the lamina terminalis is a simple and easy technique that can be used as an alternative to conventional ventriculostomy. This procedure can be indicated in cases where the ventricule is not reached by means of another technique, and when the decision to perform ventriculostomy is made at the end of aneurysm surgery.     

2058例重型颅脑创伤颅内压动态监护分析

目的 探讨颅内压(intraeranial pressure,ICP)持续动态监护对重型颅脑创伤(severe traumatic brain injury,sTBI)救治的指导意义.方法 分别采用脑窜内及脑实质内ICP监护法,对2058例sTBI患者进行ICP持续动态监护,观察ICP与患者生命体征、临床表现和预后的关系,分析其对脑室外引流及其他降颅压治疗的指导作用.结果 ICP持续动态监护末并发严重颅内感染及出血,脑室外引流对持续ICP增高者有显著的治疗作用,ICP值与患者预后呈显著负相关.结论 ICP持续动态临护安全、易行,其有助于sTBI患者病情变化的及时、正确判断,能为临床医生制定治疗方案及预后病人评估提供重要的参考依据.     

An epidural intracranial pressure monitor for experimental use in the rat

We described the construction and use of a simple and reliable catheter system that can be used to monitor intracranial pressure (ICP) from the epidural space in rats in an experimental setting. The catheter system is easily fabricated in the laboratory from readily available materials. The monitor is fitted flush with the inner table through a burr hole in the temporal squama. A side port is used to fill the system with saline and to irrigate the system should be catheter become obstructed. The distal end of the catheter is fitted to a pressure transducer that is connected to a graphic display and recording system. This system was used to record ICP in 30 anaesthetized adult rats. Seven were subjected to baseline ICP recording only and 23 were subjected to baseline recordings followed by epidural balloon compression of the contralateral hemisphere. Baseline ICP varied between 0 and 8 mmHg and respiratory variation could be detected on the tracings for 24 rats (75%). ICP responded directly and sensitively to epidural balloon inflation in all 23 rats tested. In 5 rats that died during balloon inflation, the decrease in ICP after death followed closely the loss of arterial blood pressure. There was a close correlation of numerical values obtained in two rats in which ICP was recorded simultaneously from the epidural catheter and from a catheter in the subarachnoid space at the cisterna magna. In one rat in which ICP increased to more than 70 mmHg, the epidural catheter continued to record ICP accurately while the cisternal catheter became obstructed with herniated brain.(ABSTRACT TRUNCATED AT 250 WORDS)     

Monitoring and interpretation of intracranial pressure

Intracranial pressure (ICP) is derived from cerebral blood and cerebrospinal fluid (CSF) circulatory dynamics and can be affected in the course of many diseases of the central nervous system. Monitoring of ICP requires an invasive transducer, although some attempts have been made to measure it non-invasively. Because of its dynamic nature, instant CSF pressure measurement using the height of a fluid column via lumbar puncture may be misleading. An averaging over 30 minutes should be the minimum, with a period of overnight monitoring in conscious patients providing the optimal standard. Computer-aided recording with online waveform analysis of ICP is very helpful. Although there is no "Class I" evidence, ICP monitoring is useful, if not essential, in head injury, poor grade subarachnoid haemorrhage, stroke, intracerebral haematoma, meningitis, acute liver failure, hydrocephalus, benign intracranial hypertension, craniosynostosis etc. Information which can be derived from ICP and its waveforms includes cerebral perfusion pressure (CPP), regulation of cerebral blood flow and volume, CSF absorption capacity, brain compensatory reserve, and content of vasogenic events. Some of these parameters allow prediction of prognosis of survival following head injury and optimisation of "CPP-guided therapy". In hydrocephalus CSF dynamic tests aid diagnosis and subsequent monitoring of shunt function.     

Pressure gradients within the central nervous system

The existence of clinically relevant pressure gradients within the central nervous system (CNS) is the subject of ongoing debate. Such gradients, if they do exist, would have significant implications for intracranial pressure (ICP) monitoring and ICP management in traumatic brain injury. As summarised in this short review, there is considerable experimental and clinical evidence that ICP is not evenly distributed within the central nervous system. Larger clinical trials on the implications of ICP gradients are warranted to address questions on the correct placement of ICP probes and on ICP management. It seems paradoxical to develop and employ ever more sophisticated monitoring devices in traumatic brain injury, such as monitoring of CNS metabolites with microdialysis or near-infrared spectroscopy, while fundamental issues such as the existence of ICP gradients remain unresolved.     

Intracranial Pressure Monitoring: Fundamental Considerations and Rationale for Monitoring

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In large part critical care for TBI is focused on the identification and management of secondary brain injury. This requires effective neuromonitoring that traditionally has centered on intracranial pressure (ICP). The purpose of this paper is to review the fundamental literature relative to the clinical application of ICP monitoring in TBI critical care and to provide recommendations on how the technique maybe applied to help patient management and enhance outcome. A PubMed search between 1980 and September 2013 identified 2,253 articles; 244 of which were reviewed in detail to prepare this report and the evidentiary tables. Several important concepts emerge from this review. ICP monitoring is safe and is best performed using a parenchymal monitor or ventricular catheter. While the indications for ICP monitoring are well established, there remains great variability in its use. Increased ICP, particularly the pattern of the increase and ICP refractory to treatment is associated with increased mortality. Class I evidence is lacking on how monitoring and management of ICP influences outcome. However, a large body of observational data suggests that ICP management has the potential to influence outcome, particularly when care is targeted and individualized and supplemented with data from other monitors including the clinical examination and imaging.