Telemetric Pressure Sensor Research Articles

Radiotelemetric assessment of intracavernosal pressure in apomorphine-induced erection: hypercholesterolemic rats vs normal control

A recording of the intracavernosal pressure (ICP) in conscious rats using telemetry has the advantage of being able to evaluate erection under physiological conditions. The aim of this study was to determine whether the radiotelemetric assessment of ICP in apomorphine-induced erection is appropriate for assessing erectile function in an animal model of disease. Seven rats were assigned to the normal group, and another nine rats were assigned to the hypercholesterolemia group. A telemetric pressure sensor was implanted in the corpus cavernosum. Pressure was recorded in freely moving animals after apomorphine injection. Sexual events were visually identified and recorded. Only the pressure increase occurring during sexual behavior was analyzed. The main outcome measures were as follows: latency for first peak after injection (latency), duration, maximum ICP (Max ICP) and area under the curve (AUC). The mean latency, mean duration of each episode, mean Max ICP, mean AUC and mean summed AUC were 389.9 ± 59.4 s, 61.6 ± 7.8 s, 140.0 ± 22.5 mm Hg, 1834.4 ± 358.2 mm Hg s and 3259.1 ± 795.9 mm Hg s, respectively, for the normal group vs 652.8 ± 102.2 s, 32.4 ± 5.2 s, 92.7 ± 6.4 mm Hg, 572.9 ± 73.6 mm Hg s and 739.9 ± 87.2 mm Hg s, respectively, for the hypercholesterolemia group. There was a significant difference in mean latency, mean AUC and mean summed AUC. Additionally, we cannot find any obvious immediate adverse events after surgical implantation in both normal control and hypercholesterolemic rats. And, no catheter displacement and no adverse local reaction, including fibrosis to the implant, were observed. In conclusion, radiotelemetric assessment of ICP in apomorphine-induced erection provided consistent and accurate data during erectile events, and was appropriate for assessing erectile function in an animal model of disease.

Detecting endoleaks after endovascular AAA repair with a minimally invasive, implantable, telemetric pressure sensor: an in vitro study

A feasibility study on a completely digital telemetric pressure sensor (TPS) to detect endoleaks was performed in an in vitro model of an abdominal aortic aneurysm (AAA). An endovascular-stented AAA silicone model with different types (I-III) and sizes (3-11 French) of endoleaks was created and pulsatile pressure was applied with physiological flow and pressure rates [mean intraaortic pressure (IAP): 95-130 mmHg] and different degrees of thrombosis of the aneurysm sac. Aneurysm sac pressure (ASP) was measured with the TPS and with wired pressure sensors (WPS) as a reference. Statistical analysis included paired t-test, Pearson's correlation analysis and Bland-Altman plots. After opening an endoleak, the mean ASP increased significantly (P < 0.0001) from 15 to almost 95% of the mean IAP depending on endoleak type and size. ASP could be measured accurately with the TPS and the WPS. The telemetric and wired ASP increase showed a high Pearson's correlation coefficient (r) for a non-thrombosed (r = 0.97) and a thrombosed (r = 0.96) aneurysm sac. In an in vitro silicone model, the newly designed telemetric pressure sensor was able to detect the occurrence of an endoleak in a non-invasive way and might be a valuable device for follow-up of endovascular AAA repair.

Medical aspects of active implants in the eye

Due to progress in miniaturizing complex electronic systems the development of intraocular sensors and stimulators is feasible. The Retina Implant will restore vision in patients with progressive retinal degenerations by means of electrical stimulation of retinal neurons, e.g. in Retinitis pigmentosa. After severe destructions of the anterior segment with intact retina, e.g. after explosion trauma an intraocular display will restore vision. In glaucoma patients the implantation of a telemetric pressure sensor will help to optimise the management of each individual patient. Pressure profiles under everyday conditions will become available. These active implants will open new perspectives in treatment and diagnostics in ophthalmology.

The relationship between ventricular fluid pressure and body position in normal subjects and subjects with shunts

Using a chronically implanted telemetric pressure sensor, we have determined the quantitative relationship between changes in body position and ventricular fluid pressure in normal subjects and subjects with shunts. The method allows accurate, reliable measurement of negative as well as positive pressures. We describe the derangement of postural intraventricular pressure regulation caused by placement of a shunt, as well as the influence of various shunt systems and the antisiphon device on this problem. Ventriculoatrial, ventriculoperitoneal, and ventriculopleural shunts all caused similar severely abnormal postural intracranial pressure relationships. The antisiphon device was generally effective in restoring normal pressures in patients in the upright position. We discuss the implications of our findings for understanding the mechanisms of postural intracranial pressure regulation in patients without hydrocephalus.

The Relationship between Ventricular Fluid Pressure and Body Position in Normal Subjects and Subjects with Shunts: A Telemetric Study

Abstract Using a chronically implanted telemetric pressure sensor, we have determined the quantitative relationship between changes in body position and ventricular fluid pressure in normal subjects and subjects with shunts. The method allows accurate, reliable measurement of negative as well as positive pressures. We describe the derangement of postural intraventricular pressure regulation caused by placement of a shunt, as well as the influence of various shunt systems and the antisiphon device on this problem. Ventriculoatrial, ventriculoperitoneal, and ventriculopleural shunts all caused similar severely abnormal postural intracranial pressure relationships. The antisiphon device was generally effective in restoring normal pressures in patients in the upright position. We discuss the implications of our findings for understanding the mechanisms of postural intracranial pressure regulation in patients without hydrocephalus.