Telemetric Implantable Pressure Sensor for Short- and Long-Term Monitoring of Intracranial Pressure

The ability of an implanted mediastinal pressure sensor to produce a stable respiratory signal that could be used to trigger stimulation of upper airway muscles was examined. In 6 dogs, a pressure sensor was secured to the manubrium (4 by wires and 2 by transmanubrial placement). In 6 other dogs, the pressure sensor was placed in the upper anterior mediastinum. The animals were monitored for a minimum of 8 weeks (2 transmanubrial sensors for 12 months). Sensors that were able to maintain a midline position, high in the mediastinum, had the best signals. A caudal sensor position or abutment against an intrathoracic structure caused signal inversion (unusable signals). Transmanubrial placement resulted in a stable signal for 1 year. We conclude that long-term monitoring of respiration with a mediastinal pressure sensor can be successfully performed in dogs, providing an adequate signal for nerve-muscle stimulation. Separation from cardiovascular structures improves signal quality.

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CFRP Strengthening and Long-Term Monitoring of an Old Metallic Roadway Bridge in Melbourne

IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management ◽

10.2749/guimaraes.2019.0360 ◽

2019 ◽

Author(s):

Elyas Ghafoori ◽

Ardalan Hosseini ◽

Riadh Al-Mahaidi ◽

Xiao-Ling Zhao ◽

Masoud Motavalli ◽

...

Keyword(s):

Maximum Tensile Stress ◽

Before And After ◽

Carbon Fibre Reinforced Polymer ◽

Fibre Reinforced Polymer ◽

Short And Long Term ◽

Heavy Truck ◽

Long Term Monitoring ◽

One Year ◽

Term Monitoring

<p>This study gives an overview on carbon fibre-reinforced polymer (CFRP) strengthening and wireless sensor network (WSN) monitoring of a 121-year-old metallic roadway bridge in Melbourne, Australia. A flat prestressed unbonded retrofit (FPUR) system was developed to apply prestressed CFRP plates to the steel cross-girders of Diamond-Creek Bridge. The bridge is subjected to daily passenger and heavy truck vehicles. Sets of laboratory tests were performed to examine the efficiency and fatigue performance of the proposed FPUR system, prior to its installation on the bridge. Furthermore, in order to demonstrate the efficiency of the proposed retrofit technique, the bridge was instrumented with different types of sensors (including strain gauges, temperature and humidity sensors), and short- and long-term measurements were performed. As for short-term measurements, the bridge was loaded by a 42.5-tonne semi-trailer before and after strengthening. For the long-term monitoring, a WSN system was used to monitor the prestress level in the CFRP reinforcements for at least one year. The CFRP plates were prestressed up to about 980 MPa (38% of the CFRP ultimate strength), which resulted in about 50% reduction in the maximum tensile stress in the bottom flanges of the strengthened I-girders. The results of the short- and long-term measurements in this study showed that the proposed FPUR system can be very effective for flexural and fatigue strengthening of such bridge girders.</p>

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A novel method for long-term monitoring of intracranial pressure in rats

Journal of Neuroscience Methods ◽

10.1016/j.jneumeth.2014.01.036 ◽

2014 ◽

Vol 227 ◽

pp. 1-9 ◽

Cited By ~ 23

Author(s):

Maria Uldall ◽

Marianne Juhler ◽

Anders Daehli Skjolding ◽

Christina Kruuse ◽

Inger Jansen-Olesen ◽

...

Keyword(s):

Intracranial Pressure ◽

Novel Method ◽

Long Term Monitoring ◽

Term Monitoring

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Long-term testing of an intracranial pressure monitoring device

Journal of Neurosurgery ◽

10.3171/jns.2000.93.5.0852 ◽

2000 ◽

Vol 93 (5) ◽

pp. 852-858 ◽

Cited By ~ 18

Author(s):

Jeffrey S. Kroin ◽

Robert J. McCarthy ◽

Lee Stylos ◽

Keith Miesel ◽

Anthony D. Ivankovich ◽

...

Keyword(s):

Intracranial Pressure ◽

Pressure Sensors ◽

Tissue Reaction ◽

Capacitive Transducer ◽

Content Type ◽

Csf Pressure ◽

Long Term Monitoring ◽

Term Monitoring ◽

Fine Print

Object. Long-term monitoring of intracranial pressure (ICP) is limited by the lack of an implantable sensor with low drift. The goal of this study was to demonstrate that a new capacitive transducer system will produce accurate and stable ICP records over extended periods.Methods. Intracranial pressure sensors were implanted into the frontal white matter of four dogs. In addition, a fluid-filled catheter was placed in the cisterna magna (CM) to measure cerebrospinal fluid (CSF) pressure. The animals were tested using standard physiological maneuvers such as jugular vein compression, head elevation, and CSF withdrawal from and saline injection into the CM to verify that the ICP sensor precisely matched CSF pressure changes. The mean ICP pressure and CM pressure were compared for months to demonstrate that the transducer system produced minimal drift over time.The change in the ICP sensor record closely duplicated that of the CSF waveform in the CM in response to well-known physiological stimuli. More important, mean ICP pressure remained within 3 mm Hg of CM pressure for months, with a mean difference of less than 0.3 mm Hg. Histological examination of the dog brains revealed only minimal tissue reaction to the presence of the sensor.Conclusions. The authors demonstrate a new implantable solid-state sensor that reliably measures ICP for months, with minimal drift. The clinical application of this sensor and its telemetry is for long-term monitoring of patients with head injury, mass lesions, and hydrocephalus.

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