41 research outputs found

    An Optical Fiber Photoplethysmographic System for Central Nervous System Tissue

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    Evaluation of Electrical and Optical Plethysmography Sensors for Noninvasive Monitoring of Hemoglobin Concentration

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    Completely noninvasive monitoring of hemoglobin concentration has not yet been fully realized in the clinical setting. This study investigates the viability of measuring hemoglobin concentration noninvasively by evaluating the performance of two types of sensor using a tissue phantom perfused with a blood substitute. An electrical sensor designed to measure blood volume changes during the cardiac cycle was used together with an infrared optical sensor for detection of erythrocyte-bound hemoglobin. Both sensors demonstrated sensitivity to changes in pulse volume (plethysmography). The electrical sensor produced a signal referred to as capacitance plethysmograph (CPG) a quantity which was invariant to the concentration of an infrared absorbing dye present in the blood substitute. The optical sensor signal (photoplethysmograph) increased in amplitude with increasing absorber concentration. The ratio PPG:CPG is invariant to pulse pressure. This quantity is discussed as a possible index of in vivo hemoglobin concentration

    Impact of autoimmune thyroiditis on primary hyperparathyroidism

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    Aim. Primary hyperparathyroidism (PHPT) often coexists with thyroid diseases. Current guidelines advise preoperative ultrasound (US) examination of the thyroid gland for thyroid nodular disease or concomitant malignancy but not evaluation for autoimmune thyroiditis (AIT). The impact of autoimmune thyroiditis on the clinical presentation and intraoperative course of PHPT is not clear. Material and methods. We retrospectively assessed the medical records of 21 patients with PHPT who underwent parathyroidectomy. Clinical, biochemical, ultrasonographic and intraoperative data were evaluated. Results. There was a longer duration of parathyroidectomy in patients with AIT than in those without (113.3 min vs. 93.9 min, P=0.03). A lower rate of kidney stones was noted in patients with autoimmune thyroiditis (44.4% vs. 0%, P=0.03). Patients with AIT were more symptomatic, but this was not significant. There was no difference between the two groups in the prevalence of osteoporosis or thyroid nodular disease. Conclusions. A significantly longer duration of parathyroidectomy was seen in PHPT patients with AIT. Patients with PHPT undergoing surgery should be investigated for autoimmune thyroiditis, as this may affect surgical planning
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