Clinical experience with a fiberoptic intracranial pressure monitor

Fiber-Optic Intracranial Pressure Monitoring System Using Wi-Fi-An In Vivo Study

BACKGROUND

Continuous invasive monitoring of intracranial pressure (ICP) is essential in neurocritical care for surveillance and management of raised ICP. Fluid-based systems and strain gauge microsensors remain the current standard. In the past few decades, several studies with wireless monitoring were developed aiming to reduce invasiveness and complications.

OBJECTIVE

To describe a novel Wi-Fi fiber-optic device for continuous ICP monitoring using smartphone in a swine model.

METHODS

Two ICP sensors (wireless prototype and wire-based reference) were implanted in the cerebral parenchyma of a swine model for a total of 120 minutes of continuous monitoring. Every 5 minutes, jugular veins compression was performed to evaluate ICP changes. The experimentation was divided in 3 phases for comparison and analysis.

RESULTS

Phase 1 showed agreement in ICP changes for both sensors during jugular compression and releasing, with a positive and strong Spearman correlation (r = 0.829, P < .001). Phase 2 started after inversion of the sensors in the burr holes; there was a positive and moderately weak Spearman correlation (r = 0.262, P < .001). For phase 3, the sensors were returned to the first burr holes; the prototype behaved similarly to the reference sensor, presenting a positive and moderately strong Spearman correlation (r = 0.669, P < .001).

CONCLUSION

A Wi-Fi ICP monitoring system was demonstrated in a comprehensive and feasible way. It was possible to observe, using smartphone, an adequate correlation regarding ICP variations. Further adaptations are already being developed.

Bedside burr hole for intracranial pressure monitoring performed by pediatric intensivists in children with CNS infections in a resource-limited setting: 10-year experience at a single center

OBJECTIVE

Intracranial pressure monitoring can help in early identification of raised intracranial pressure and in setting more informed goals for treatment. We describe our 10-year experience of bedside burr holes performed by pediatric intensivists to establish intracranial pressure monitoring in children with CNS infections in a resource-limited setting and the technical difficulties and complications encountered.

DESIGN

Descriptive study of prospectively recorded data.

SETTING

PICU of a tertiary care academic institute.

PATIENTS

Consecutive comatose patients with raised intracranial pressure who underwent intracranial pressure monitoring from 2004 to 2013.

INTERVENTION

An intraparenchymal (1.2 mm) or an intraventricular transducer (3.4 mm) (Codman) was placed by a pediatric intensivist through a micro burr hole using a standard protocol. Technical difficulties during the procedure and complications were recorded.

MEASUREMENTS AND MAIN RESULTS

Over 10 years, 265 intracranial pressure catheters were placed in 259 patients, mainly for acute CNS infections (n = 242, 93.4%). Median age of patients was 4.8 years, youngest being 6 weeks; 21 patients (8.1%) were younger than 1 year. Intraparenchymal transducer was used in 252 patients (97.3%). Median (interquartile range) duration of intracranial pressure monitoring was 96 hours (72-144 hr). Complications were seen in 3.5% of patients (n = 9/259); the incidence was 0.28 per 1,000 hours of intracranial pressure monitoring. Procedure-related ventriculitis occurred in three of seven patients (42.8%) with intraventricular catheter, in contrast to none in patients with intraparenchymal transducer. Overall mortality was 32.8% (n = 85). On Cox-regression analysis, "blood component therapy" was an independent predictor of poor outcome defined as death or severe neurodisability (adjusted hazard ratio, 1.58; 95% CI, 1.16-2.16; p = 0.004).

CONCLUSIONS

In a resource-limited setting, pediatric intensivists can safely and successfully perform burr holes at bedside for establishing intraparenchymal intracranial pressure monitoring in children with acute CNS infections. However, our data do not support placement of ventriculostomy catheters by pediatric intensivists in similar settings.

Infection Rates in Standard vs. Hydrogel Coated Ventricular Catheters

Background:

Infection related to external ventricular drain (EVD) use is a common neurosurgical complication. Modified catheters with a hydrophilic surface may impede bacterial adherence and thereby reduce catheter related cerebrospinal fluid (CSF) infection.

Methods:

A prospective randomized clinical trial compared the occurrence of CSF infection related to use of either standard silastic or hydrogel coated EVD catheters (Bioglide®, Medtronic). Enrolment was available to all adult neurosurgery patients undergoing placement of a first EVD, at three university centers. The catheters were presoaked in a low concentration of bacitracin solution for 5-10 minutes prior to insertion. Bacterial infection was defined by heavy growth in a single CSF sample or light / medium growth in two consecutive samples. A secondary analysis was also conducted for “probable” CSF infection, including patients started on antibiotics after light / medium growth in a single CSF sample. Statistical analyses included Kaplan-Meier survival curve estimates accompanied by Log Rank and Breslow tests.

Results:

There were 158 randomized patients available to assess for EVD related infection of CSF. The two study groups had similar clinical characteristics including average duration of EVD use (8±4 days). Definite CSF infection occurred in seven and probable infection in another six (8% total). Infection incidence rose steadily from day 2 (1%) to day 11 (11%). There was no difference of daily occurrence of EVD infection between the two catheter types.

Conclusion:

Infection remains a common hazard in the use of EVD, and we found no reduction of infection using the hydrogel-coated catheters when presoaked in low concentration bacitracin solution.

Subdural intracranial pressure monitoring in severe head injury: clinical experience with the Codman MicroSensor

BACKGROUND

Our main objective was to study the clinical outcome and complications of the subdural ICP monitoring with the CMS (Johnson and Johnson Medical Ltd, Raynhan, MA) in severe head injury.

METHODS

A retrospective analysis of patients with head injury with a GCS score of 8 or less was performed. Patients with severe systemic injury with hypotension (systolic blood pressure of <90 mm Hg on admission), a GCS score of 3 with fixed and dilated pupils after resuscitation, a GCS score of 3 to 4 whose family refused aggressive treatment, and those who were dead on arrival were excluded from this study. During the period from January 1997 to April 2004, 120 patients with severe head injuries were included and met criteria for insertion of a subdural ICP monitoring device (CMS).

RESULTS

A total of 120 patients (84 males and 36 females), aged 16 to 80 years old (mean, 43.8 +/- 14.4), were enrolled in the study. The average duration of ICP monitoring device use was 7.6 +/- 0.4 days (range, 2-14 days). The overall clinical outcomes of these patients were as follows: mortality rate, 13.5%; percentage of unfavorable outcomes, 17.3%; percentage of favorable outcomes, 69.2%. There were no complications such as CNS infection or hemorrhage in this study.

CONCLUSION

A subdural transducer-tipped catheter (CMS) can be used as the first-line equipment for monitoring ICP in patients with severe head injury. The clinical results are similar with other recent studies, but no complication such as infection or hemorrhage occurred in this study.

Intracranial pressure monitoring: why monitor?

Evidence suggests that the mortality and morbidity of acquired brain injury could be reduced if clinicians used an aggressive intracranial pressure guided approach to care. Despite nearly 50 years of evidence that intracranial pressure monitoring benefits patient care, only about half of the patients who could benefit are monitored. Some clinicians express concerns regarding risks such as bleeding, infections, and inaccuracy of the technology. Others cite cost as the reason. This article discusses the risks and benefits of intracranial pressure monitoring and the current state of evidence of why patients should be monitored.

Bedside invasive monitoring techniques in severe brain-injured patients

In patients with severe brain injury, brain edema, elevated intracranial pressure, and cerebral ischemia are accountable for a significant morbidity and mortality. New invasive methods of monitoring attempt to foresee the physiopathological mechanisms responsible for the production of secondary brain injuries. The available methods for monitoring severely brain-injured patients, their potential usefulness, advantages, and disadvantages are reviewed.

The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Recommendations for intracranial pressure monitoring technology

In patients who require ICP monitoring, a ventricular catheter connected to an external strain gauge transducer or catheter tip pressure transducer device is the most accurate reliable method of monitoring ICP and enables therapeutic CSF drainage. Clinically significant infections or hemorrhage associated with ICP devices causing patient morbidity are rare and should not deter the decision to monitor ICP. Parenchymal catheter tip pressure transducer devices measure ICP similar to ventricular ICP pressure but have the potential for significant measurement differences and drift due to the inability to recalibrate. These devices are advantageous when ventricular ICP is not obtained or if there is obstruction in the fluid couple. Subarachnoid or subdural fluid coupled devices and epidural ICP devices are currently less accurate.

Intrahospital transport of critically ill patients

BACKGROUND

This review on the current literature of the intrahospital transport of critically ill patients addresses type and incidence of adverse effects, risk factors and risk assessment, and the available information on efficiency and cost-effectiveness of transferring such patients for diagnostic or therapeutic interventions within hospital. Methods and guidelines to prevent or reduce potential hazards and complications are provided.

METHODS

A Medline search was performed using the terms 'critical illness', 'transport of patients', 'patient transfer', 'critical care', 'monitoring' and 'intrahospital transport', and all information concerning the intrahospital transport of patients was considered.

RESULTS

Adverse effects may occur in up to 70% of transports. They include a change in heart rate, arterial hypotension and hypertension, increased intracranial pressure, arrhythmias, cardiac arrest and a change in respiratory rate, hypocapnia and hypercapnia, and significant hypoxaemia. No transport-related deaths have been reported. In up to one-third of cases mishaps during transport were equipment related. A long-term deterioration of respiratory function was observed in 12% of cases. Patient-related risk indicators were found to be a high Therapeutic Intervention Severity Score, mechanical ventilation, ventilation with positive end-expiratory pressure and high injury severity score. Patients' age, duration of transport, destination of transport, Acute Physiology and Chronic Health Evaluation II score, personnel accompanying the patient and other factors were not found to correlate with an increased rate of complications. Transports for diagnostic procedures resulted in a change in patient management in 40-50% of cases, indicating a good risk:benefit ratio.

CONCLUSIONS

To prevent adverse effects of intrahospital transports, guidelines concerning the organization of transports, the personnel, equipment and monitoring should be followed. In particular, the presence of a critical care physician during transport, proper equipment to monitor vital functions and to treat such disturbances immediately, and close control of the patient's ventilation appear to be of major importance. It appears useful to use specifically constructed carts including standard intensive care unit ventilators in a selected group of patients. To further reduce the rate of inadvertent mishaps resulting from transports, alternative diagnostic modalities or techniques and performing surgical procedures in the intensive care unit should be considered.

Intracranial pressure monitor placement by midlevel practitioners

BACKGROUND

The timely treatment of patients with head injuries is affected by the availability and commitment of neurosurgeons. Use of midlevel practitioners (MLPs) may permit more efficient neurosurgical coverage. Intracranial pressure monitoring is among the most frequently used neurosurgical procedures. The purpose of this study was to examine the placement of intracranial pressure (ICP) monitors by MLPs.

METHODS

Medical records and trauma registry data for a Level I trauma center were reviewed from December 1993 to June 1997. Patients who had ICP monitors placed were included. Patient data recorded were age, mechanism of injury, injury type, ICP monitor placement and length of placement, complications related to the ICP monitor, and outcomes.

RESULTS

Two hundred ten patients had 215 monitors placed. ICP monitors were placed by neurosurgeons (105), MLPs (97), and general surgery residents (13), and remained in place a mean of 4 days. No major complications attributable to ICP monitor placement occurred; 19 minor complications (malfunction, dislodgment) were noted. Eleven monitors placed by neurosurgeons (10%), seven placed by MLPs (7%), and one placed by a resident (8%) had complications.

CONCLUSION

ICP monitor placement by MLPs is safe. Use of MLPs may aid neurosurgeons in providing prompt monitoring of patients with head injuries.

Comparison of percutaneous ventriculostomies and intraparenchymal monitor: a retrospective evaluation of 156 patients

Intraventricular catheters (IVC) and Intraparenchymal fiberoptic catheters (IPC) are the prevalent methods of intracranial pressure (ICP) monitoring. This study assesses the complications caused by either method. Previous studies have shown a higher complication rate with IVC. In 156 consecutive patients, with IVC (n = 104) or IPC (n = 52) insertion, the demographics, Glasgow coma score (GCS), ICP, duration of monitoring, changes in monitoring device, complications and computerized tomography findings, were recorded. The patients were categorized into severe (GCS 3-8), moderate (GCS 9-12) and mild (GCS 13-15) groups. A retrospective, comparative analysis of both techniques was conducted, using Kruskal-Wallis one way analysis of variance with chi square approximation and Mann-Whitney U tests. The use of IPC at 86.5% predominated in patients with GCS 3-8, while IVC at 81.4% and 92% prevailed in GCS groups 9-12 and 13-15, respectively (p = 0.000). 43.2% IVC were used for 10+ days and 25.9% for 1-3 days, while 80% of IPC were used for less than 6 days (p = 0.000). The complication rate for IVC and IPC was 25% vs 4.4% (p = 0.000). The infection rate was 4.4% and 0.6% (p = 0.1) while, inadvertent removal 4.4% vs 1.2% (p = 0.4), respectively. Malpositions occurred only with IVC (20.1%). All documented complications were without untoward clinical sequelae. We conclude that, IVC remains comparable to IPCs in complications.

[Techniques for measuring intracranial hypertension]

A wide variety of monitoring devices have been used for intracranial pressure measurement. The aim of this article is to present the most common devices and to assess their accuracy, stability and complications, with reference to current literature. Measurement with an intraventricular catheter remains, the reference method. However new techniques with distal measurement (fiberoptic or strain gauge) seem to be accurate, but have a higher cost. Some practical problems, such as the zero pressure reference level and the side of measurement, are also discussed.

Assessment of the CAMINO intracranial pressure device in clinical practice

The purpose of this study was to investigate reliability, handling characteristics and complication rate of the CAMINO-ICP-monitor-system in clinical routine. In a case controlled study 82 patients with intracranial pathology necessitating ICP-monitoring received either a ventricular or a parenchymal CAMINO-device. Clinical assessment of curve shape and apparent reliability of the measurement was documented. Probe position and presence of hematoma was evaluated in all patients with a CT after probe insertion. Handling complications, i.e. dislocation were recorded. At the end of the measuring period the drift of the probe was checked ex vivo and a two point calibration was performed using a water column. During one year 82 patients received 95 probes (parench, 73. ventric. 22). The average measuring period was 91.3 +/- 70.6 hrs. Catheter position was verified by CCT for 67 (70.5%) probes. 92.5% of the devices were placed correctly. Clinically 88.4% of the measurements were assessed plausible, in 8.2% the displayed ICP-values were judged to be too high, in 2.1% too low. Probe drift after explanation was -0.21 mmHg/24 hrs. The mean value of the recalibrated probes in the water column corresponding to 15.8 mmHg was 14.7 +/- 1.9 mmHg. There was no correlation between neither drift nor function in the water column and the duration of the measurement. Technical complications exclusively related to the construction of the CAMINO-system like kinking of the cable, dislocation (probe pulled out) or dislocated fixation screw were too high (25.3%).

Atrial distension in humans during microgravity induced by parabolic flights

The hypothesis was tested that human cardiac filling pressures increase and the left atrium is distended during 20-s periods of microgravity (microG) created by parabolic flights, compared with values of the 1-G supine position. Left atrial diameter (n = 8, echocardiography) increased significantly during microG from 26.8 +/- 1.2 to 30.4 +/- 0.7 mm (P < 0.05). Simultaneously, central venous pressure (CVP; n = 6, transducer-tipped catheter) decreased from 5.8 +/- 1.5 to 4.5 +/- 1.1 mmHg (P < 0.05), and esophageal pressure (EP; n = 6) decreased from 1.5 +/- 1.6 to -4.1 +/- 1.7 mmHg (P < 0.05). Thus transmural CVP (TCVP = CVP - EP; n = 4) increased during microG from 6.1 +/- 3. 2 to 10.4 +/- 2.7 mmHg (P < 0.05). It is concluded that short periods of microG during parabolic flights induce an increase in TCVP and left atrial diameter in humans, compared with the results obtained in the 1-G horizontal supine position, despite a decrease in CVP.

Prospective study of zero drift in fiberoptic pressure monitors used in clinical practice

One hundred and one fiberoptic pressure transducers (59 subdural and 42 ventricular) were studied in 86 patients (some in whom more than one device had been inserted). Only four complications occurred: two transient cerebrospinal fluid leaks after removal and two clinically insignificant intracerebral hematomas. No intracranial infections could be attributed to the devices. Technical problems occurred 23 times, with 11 devices ceasing to function before removal, seven becoming displaced, and five microventricular catheters failing to enter the ventricles. Zero-drift readings were obtained for 83 devices at the time of removal (median 66 hours after insertion, range 2 hours-13 days). There was a clear negative bias in the readings (median -3), with a wide range of values (-12 to +14 mm Hg; interquartile range -6 to -1) that was apparent even in the first 3 days of use. There was no important relationship between zero drift and any recorded variable. It is concluded that zero drift of fiberoptic pressure transducers is a significant problem and that undue reliance should not be placed on intracranial pressure readings from these devices in isolation from other clinical and radiological information.

Bedside burr hole for intracranial pressure monitoring performed by intensive care physicians. A 5-year experience

OBJECTIVE

To assess the results of a 5-year experience with bedside burr hole for intracranial pressure (ICP) monitoring performed by intensive care physicians.

DESIGN

Prospective, observational study in 120 patients.

SETTING

A general-neurologic Intensive Care Unit in a University Hospital.

PATIENTS

Patients admitted for acute neural lesion requiring ICP monitoring.

METHOD

A 2.71 mm burr hole was made with positioning of a subarachnoid screw, through which a miniaturized fiberoptic, tip transducer device (Camino) was advanced and inserted 2 mm in the frontal cortex.

MAIN RESULTS

Over a 5-year period 120 patients, mainly with severe head trauma, underwent ICP monitoring. None of the planned patients was excluded because of technical difficulties. No life-threatening complications were reported, and the overall morbidity rate related to the ICP monitor was 3.3%. Complications were infectious in nature, with 2.5% wound infections and 0.8% meningitis. Although seven patients bled when opening the dura, no intracranial hematomas were recorded due to the ICP monitor. The fiberoptic device was left in place for 5 +/- 1.6 (SD) days (range 1-12 days). Five patients (4.1%) required catheter substitution due to breakage of the system components (fiberoptics).

CONCLUSIONS

Bedside insertion of a ICP monitor performed by intensive care physicians is a safe procedure, with a complication rate comparable to other series published by neurosurgeons. The overall morbidity rate is comparable to, or even lower than, that caused by central vein catheterization.