Clark T.M.,University of Auckland |
Clark T.M.,Millar Inc. |
Malpas S.C.,University of Auckland |
McCormick D.,University of Auckland |
And 2 more authors.
IEEE Sensors Journal | Year: 2015
Hydrocephalus is the single most common pediatric neurosurgical problem worldwide. Current treatment of this life-threatening disorder involves diverting excess fluid from the ventricles of the brain via a prosthetic shunt. While many hydrocephalus sufferers rely heavily on their ventriculo-distal shunt to maintain a healthy intracranial pressure, shunts carry a high risk of failure. Current methods of assessing shunt patency are performed within the hospital, and many patients and their families feel bound to remaining within close proximity of a hospital in order to receive timely medical intervention in the event of a shunt failure. There is a need for a system which can detect shunt malfunction, simply and reliably. We present a novel method of obtaining flow measurements from a piezoresistive pressure transducer. This builds on an earlier development of obtaining simultaneous temperature and pressure measurement from the single ultra-miniature solid-state transducer. The flow measurement system is capable of measurements in the range 0-35 ml/h, typical of the fluid flow rates through a hydrocephalus shunt. Within the flow range 0-14 ml/hour the resolution is 2 ml/hour. For flow rates greater than 16 ml/hour the resolution is 5 ml/hour. Employing a thermal flow sensing technique, the maximum heating of the local fluid is 0.65 ± 0.02 °C. The flow signal is independent of ambient temperature. The sensor would be implanted in the shunt to allow the detection of the flow rate of fluid through it, enabling the clinician to measure the patency of a shunt in real time. © 2015 IEEE.
Millar Inc. and Millar Instruments Inc. | Date: 2007-05-15
Blood glucose meter; Blood pressure measuring apparatus; Blood pressure monitors; Cardiac electrodes; Cardiac probes; Catheter based ultra-sound imaging probe; Catheters; Devices for measuring intracranial pressure; Medical diagnostic apparatus, analytical apparatus for medical purposes and blood pressure measuring apparatus; Medical electrodes; Medical instrument for cardiovascular diagnostics; Medical ultrasound apparatus; Ultrasonic medical diagnostic apparatus; Ultrasound diagnostic apparatus.
Millar Inc. | Date: 2008-02-12
EKG machines; Blood pressure measuring apparatus; Blood pressure monitors; Medical diagnostic apparatus, analytical apparatus for medical purposes and blood pressure measuring apparatus.
Guild S.-J.,University of Auckland |
Guild S.-J.,Millar Inc. |
McBryde F.D.,University of Auckland |
Malpas S.C.,University of Auckland |
Malpas S.C.,Millar Inc.
Journal of Applied Physiology | Year: 2015
cerebral perfusion pressure (CPP) is known to be fundamental in the control of normal brain function, there have been no previous long-term measurements in animal models. The aim of this study was to explore the stability and viability of long-term recordings of intracranial pressure (ICP) in freely moving rats via a telemetry device. We also developed a repeatable surgical approach with a solid-state pressure sensor at the tip of the catheter placed under the dura and in combination with arterial pressure (AP) measurement to enable the calculation of CPP. Telemeters with dual pressure catheters were implanted in Wistar rats to measure ICP and AP. We found that the signals were stable throughout the 28-day recording period with an average ICP value of 6 ±0.8 mmHg. Significant light-dark differences were found in AP (3.1 ±2.7 mmHg, P = 0.02) and HR (58 ± 2 beats/min, P = 0.003), but not ICP (0.3 ± 0.2 mmHg, P =0.05) or CPP (2.6 ± 2.8 mmHg, P ± 0.05). Use of kaolin to induce hydrocephalus in several rats demonstrates the ability to measure changes in ICP throughout disease progression, validating this new solution for chronic measurement of ICP, CPP, and AP in conscious rats. © 2015 the American Physiological Society.
Millar Inc. and Millar Instruments Inc. | Date: 1992-06-09
pressure transducers, fluid velocimeters, transducer control units, electrical continuity testers, and catheter pressure transducers for medical applications.