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Meltem Izzetoglu

Publications and source records attributed to Meltem Izzetoglu.

6 recordsLinked to original sources
PubMed2006

A novel method to measure regional muscle blood flow continuously using NIRS kinetics information.

BACKGROUND: This article introduces a novel method to continuously monitor regional muscle blood flow by using Near Infrared Spectroscopy (NIRS). We demonstrate the feasibility of the new method in two ways: (1) by applying this new method of determining blood flow to experimental NIRS data during exercise and ischemia; and, (2) by simulating muscle oxygenation and blood flow values using these newly developed equations during recovery from exercise and ischemia. METHODS: Deoxy (Hb) and oxyhemoglobin (HbO2), located in the blood of the skeletal muscle, carry two internal relationships between blood flow and oxygen consumption. One is a mass transfer principle and the other describes a relationship between oxygen consumption and Hb kinetics in a two-compartment model. To monitor blood flow continuously, we transfer these two relationships into two equations and calculate the blood flow with the differential information of HbO2 and Hb. In addition, these equations are used to simulate the relationship between blood flow and reoxygenation kinetics after cuff ischemia and a light exercise. Nine healthy subjects volunteered for the cuff ischemia, light arm exercise and arm exercise with cuff ischemia for the experimental study. RESULTS: Analysis of experimental data of both cuff ischemia and light exercise using the new equations show greater blood flow (four to six times more than resting values) during recovery, agreeing with previous findings. Further, the simulation and experimental studies of cuff ischemia and light exercise agree with each other. CONCLUSION: We demonstrate the accuracy of this new method by showing that the blood flow obtained from the method agrees with previous data as well as with simulated data. We conclude that this novel continuous blood flow monitoring method can provide blood flow information non-invasively with NIRS.

Journal Article↗
PubMed2005

Fetal transabdominal pulse oximeter studies using a hypoxic sheep model.

OBJECTIVE: This study investigates the validity of transabdominal pulse oximetry using a sheep fetal hypoxia model with fetal arterial hemoglobin saturation. METHODS: Four pregnant ewes were anaesthetized and cannulated through the brachial artery to measure direct arterial blood saturation, SaO(2). Next, the transabdominal pulse oximeter was used to measure indirect measurement of the arterial saturation of the fetus, SpO(2), from the maternal abdomen. Hypoxia was induced by a balloon placed in the maternal aorta. RESULTS: There is a linear relationship between SaO(2), arterial blood saturation values of the fetus, and SpO(2), the values measured by the transabdominal pulse oximetry with a slope of 0.75 (r(2)=0.76). CONCLUSION: This information can be used to calibrate the transabdominal pulse oximeter as a measurement of fetal arterial saturation. With these results, we can advance the accurate, no-risk, noninvasive transabdominal fetal pulse oximeter for human use. This research may contribute to the more accurate diagnosis of the diseases of the fetus including Hypoxic Ischemic Encephalopathy.

Abdomen↗
PubMed2005

Motion artifact cancellation in NIR spectroscopy using Wiener filtering.

We present a Wiener filtering based algorithm for the elimination of motion artifacts present in Near Infrared (NIR) spectroscopy measurements. Until now, adaptive filtering was the only technique used in the noise cancellation in NIR studies. The results in this preliminary study revealed that the proposed method gives better estimates than the classical adaptive filtering approach without the need for additional sensor measurements. Moreover, this novel technique has the potential to filter out motion artifacts in functional near infrared (fNIR) signals, too.

Algorithms↗
PubMed2005

Functional near-infrared neuroimaging.

Functional near-infrared spectroscopy (fNIR) is a neroimaging modality that enables continuous, noninvasive, and portable monitoring of changes in blood oxygenation and blood volume related to human brain function. Over the last decade, studies in the laboratory have established that fNIR spectroscopy provides a veridical measure of oxygenation and blood flow in the brain. Our recent findings indicate that fNIR can effectively monitor cognitive tasks such as attention, working memory, target categorization, and problem solving. These experimental outcomes compare favorably with functional magnetic resonance imaging (fMRI) studies, and in particular, with the blood oxygenation level dependent signal. Since fNIR can be implemented in the form of a wearable and minimally intrusive device, it has the capacity to monitor brain activity under real life conditions and in everyday environments. Moreover, the fNIR system is amenable to integration with other established physiological and neurobehavioral measures, including electroencephalogram, eye tracking, pupil reflex, heart rate variability, respiration, and electrodermal activity.

Algorithms↗