BACKGROUND: Accuracy of jugular venous oxygen saturation (SjvO2) measurement depends on sampling of cerebral venous outflow blood not contaminated by systemic venous blood. The influence of the rate of blood withdrawal has not been determined. METHODS: The authors examined the effect of withdrawing blood at different rates from jugular venous ...

Deep hypoxia is known to increase the intraerythrocytic 2,3 diphosphoglycerate (DPG) level and therefore to induce a right shift of the oxyhemoglobin dissociation curve (ODC), which is considered to be a protective mechanism against tissular hypoxia. Our purpose was to assess whether the ODC is shifted to the right in ...

After reperfusion of a liver graft, transcranial Doppler determined middle cerebral artery flow velocity, increases more than expected from the arterial carbon dioxide tension (PaCO2). We evaluated if this indication of cerebral hyperperfusion is reflected in the jugular oxygen saturation (SjO2) (n = 31) and oxygen saturation (ScO2) (near-infrared spectrophotometry, ...

A theoretical model predicts that forced inspiratory oxygen concentration oscillations can be used to recover cardiorespiratory data and elicit information about the oxygen transport system (Hahn, 1996). The effects of hypoxia on the penetration of these generated oxygen oscillations into arterial and venous blood were explored in dogs exposed to ...

Pulse oximetry is an important advancement in noninvasive monitoring and assessment of arterial blood oxygenation. The purpose of this study was to assess the correlation of arterial oxygen saturation (SaO2) and pulse oximetry (SpO2) in critically ill patients using the ear and finger probes. Arterial oxygen saturation was measured simultaneously ...

Pulse oximetry is a technique for estimating arterial oxygen saturation continuously and non-invasively. Reflectance pulse oximetry might become useful for monitoring the fetus during labour but it is much more susceptible to all kinds of physiological variations than the well-established transmission pulse oximetry for neonatal or adult monitoring. This review ...

OBJECTIVE: To assess the influence of the blood content of the tissue and the hemoglobin content of the blood upon pulse oximetry at oxygen saturation ranges that commonly occur in the fetus during birth. METHOD: A new in-vitro model, which differs conceptually from models used by other authors, was developed ...

Assessment of cerebral oxygenation using near-infrared spectroscopy in intensive care is increasing. We compared the ability of the Invos 3100 and the Critikon 2020 monitors to produce stable and consistent readings of regional cerebral oxygen saturation in resting volunteers. Failure to obtain any stable reading with the Critikon occurred in ...

The aim of our study was to compare, using near-infrared spectroscopy (NIRS), the effects on cerebral intracellular oxygenation and cerebral blood volume (CBV) of closed endotracheal suctioning (CS), which permits continuous ventilation of the patient, with open endotracheal suctioning (OS), which requires disconnection from the ventilator. Eleven preterm infants were ...

OBJECTIVE: A new reflectance pulse oximetry sensor, developed for intrapartum estimation of arterial oxygen saturation (SaO2), was calibrated and evaluated. The sensor contains two light emitting diodes of 735 and 890 nm, and a photodetector at a distance of 14 mm from both light emitting diodes. METHODS: In seven Yorkshire/Hampshire ...

A novel noninvasive magnetic resonance imaging (MRI) method was developed to determine in vivo blood oxygen saturation and its changes during motor cortex activation in small cerebral veins. Specifically, based on susceptibility measurements in the resting states, pial veins were found to have a mean oxygen saturation of Yrest=0.544+/-0.029 averaged ...

AIM: To study continuously cerebral blood flow velocity in the middle cerebral artery before, during, and after tube feeding in neonates. METHOD: Cerebral blood flow velocity was measured in 14 neonates using a Doppler ultrasound device. Blood pressure, respiration, and oxygen saturation were monitored. RESULTS: Mean blood flow velocity decreased ...

Invasive techniques are used for conventional measurements of cerebral blood volume and there is a need for methods which are more readily applicable clinically. We studied 13 healthy volunteers using near infrared spectroscopy and transcranial Doppler sonography. Middle cerebral artery flow velocity (vmca) and changes in cerebral oxygenated haemoglobin (HbO2), ...

BACKGROUND: When used during extracorporeal membrane oxygenation (ECMO), jugular venous bulb catheters, known as cephalad cannulae, increase venous drainage, augment circuit flow and decompress cerebral venous pressure. Optimized cerebral oxygen delivery during ECMO may contribute to a reduction in neurological morbidity. This study describes the use of cephalad cannulae and ...

OBJECTIVE: To test the ability of near-infrared spectrophotometry (NIRS) to predict vascular compromise in flaps postoperatively. DESIGN: Pilot study. SUBJECTS: Eleven denervated latissimus dorsi flaps were assessed in 8 pigs. INTERVENTIONS: Flaps were isolated on their vascular pedicle. We used NIRS to demonstrate tissue oxygen saturation and quantities of deoxygenated ...

In critically ill neonates the risk associated with rapid changes in oxygen saturation is high. Thus effective means of monitoring blood oxygen saturation is essential. While pulse oximetry is appealing because it is noninvasive and in general it correlates well with arterial blood gases (ABG), some concerns remain about its ...

Measuring arterial hemoglobin saturation via traditional arterial blood gas testing or co-oximetry complements the fundamental physical examination process. Within the last two decades, advancements in diagnostic technologies made possible the dynamic, noninvasive assessment of hemoglobin saturation through pulse oximetry. Technology assessment teams must determine the relative cost-effectiveness of these techniques ...

A commercially available pulse oximeter was evaluated in anaesthetised foals to determine its accuracy for estimating arterial haemoglobin saturation (SaO2). Five different transducer/transducer attachment site (TTAS) combinations were evaluated; 1-3) a fingertip transmission transducer attached to the foal's ear, lip and tongue, 4) an adhesive transmission transducer positioned on the ...

A case is reported of methaemoglobinaemia presenting with recurrent fits in the absence of cyanosis. A low oxygen saturation measured on pulse oximetry that fails to improve with oxygen treatment, the presence of "chocolate brown" blood that does not change on exposure to air, and a high PaO2 arterial blood ...

It is now possible to detect quantitative changes in cytochrome aa3 by means of near-infrared spectrophotometry. This technique is also suitable for determining oxidised hemoglobin (HbO2), reduced hemoglobin (Hb), cerebral blood volume, and the redox state of cytochrome aa3 (cyt aa3) in the tissues. The significance of elevated cyt aa3, ...

The aim of the study was to evaluate a new noninvasive transcranial near-infrared spectroscopy (TNIRS) technique for determination of the lower limit of cerebral blood flow (CBF) autoregulation by comparing this technique with the standard cerebral arteriovenous oxygen saturation difference (AVDo2) method. In eight healthy volunteers, mean arterial blood pressure ...

Jugular bulb oximetry can be used to assess the balance between oxygen supply and demand to the brain, measure metabolic byproducts, and determine cerebral blood flow. It has been useful in guiding the management of patients who are at risk of developing global ischemia. In this article, the principles upon ...

Electroconvulsive therapy (ECT) increases neuronal energy consumption and alters systemic hemodynamics. We examined the effects of ECT on regional cerebral oxygen saturation (rSo2) using a near-infrared spectro-photometer. Heart rate (HR), mean arterial blood pressure (MAP), and rSo2 were continuously monitored throughout ECT under general anesthesia in 43 patients. In all ...

The continuous, non-invasive real-time monitoring of arterial oxygenation (pulse oximetry) has become a standard of care in both human and veterinary medicine. It allows reliable, simple and inexpensive assessment of the arterial oxygenation status. In pigs, commonly used sites for oximetry-probe placement are the ear, snout or tongue, while more ...

although the waveform derived from a peripheral pulse monitor or pulse oximeter may resemble an arterial pressure waveform, it is in fact a visualization of blood volume change in transilluminated tissue caused by passage of blood: an indication of perfusion or blood flow. Most currently available pulse oximeters indicate this ...

A sinusoidal forcing function inert-gas-exchange model (C. E. W. Hahn, A. M. S. Black, S. A. Barton, and I. Scott. J. Appl. Physiol. 75: 1863-1876, 1993) is modified by replacing the inspired inert gas with oxygen, which then behaves mathematically in the gas phase as if it were an inert ...

OBJECTIVES: Monitoring jugular venous oxygen saturation (SjvO2) has been useful for the early identification and treatment of cerebral ischemia in patients with severe head injury. However, the catheters that have been used for this purpose have not performed optimally. The purpose of this study was to evaluate the performance of ...

Midazolam in combination with nitrous oxide (N2O) is a commonly used sedative approach for pediatric dental patients. Respiratory morbidity and mortality have been reported with midazolam administration, particularly when used in combination with other drugs in the absence of supplemental oxygen. Thus, the purpose of this investigation was to determine ...

A novel, noninvasive method for measuring peripheral venous oxygen saturation (Svo2) in newborn infants using near infrared spectroscopy (NIRS) with venous occlusion is described, along with a comparison with co-oximetry of peripheral venous blood. Peripheral Svo2 was measured in 16 newborn infants by NIRS with venous occlusion, and the results ...

BACKGROUND: Because hemodilution decreases the oxygen-carrying capacity of blood, it was hypothesized that severe hemodilution would decrease the tolerance to alveolar hypoxia. METHODS: Hemodynamics, oxygen transport, and blood lactate concentrations were compared in ten pigs with normal hematocrit (33 +/- 4%), and ten hemodiluted pigs (hematocrit 11 +/- 1%; mean ...

We have analyzed the role that instrument error plays in the oximetric diagnosis of shunts. First, we review the accuracy specifications of instruments currently available for measuring oxyhemoglobin saturation during cardiac catheterization. Then we derive a mathematical model of a left-to-right shunt and illustrate the relationships between the magnitude of ...

In conclusion, NIRS appears to offer both a new monitoring modality and new information about cerebral oxygenation. Technical problems in the application of this technology persist, most notably determination of pathlength and the volume of tissue interrogated. Those familiar with the history of pulse oximetry will recall that although Millikan ...

Current routine methods for assessment of pulp vitality rely on stimulation of A-delta nerve fibers and give no direct indication of blood flow within the pulp. Recent papers have suggested that pulse oximeters may be used to diagnose pulp vitality by detection of blood flow. In this study, an optimized ...

BACKGROUND: Near-infrared spectroscopy is a potential tool for measuring adequacy of cerebral oxygenation during cardiac operations. The cerebral microcirculation is predominantly venous (by volume) and therefore regional cerebral oxygenation measured by near-infrared spectroscopy should reflect jugular bulb venous saturations. METHODS: We compared simultaneous regional cerebral oxygenation and jugular bulb venous ...

A 4-French gauge Opticath catheter, inserted into a neonate's right atrium through the right internal jugular vein, can be used to continuously monitor venous blood oxygen saturation in the right atrium. This method instantly detects subtle changes in cardiopulmonary function in small infants and neonates and enables the appropriate treatment ...

Hemoglobin-based artificial blood substitutes as oxygen carrier is advantageous over current plasma expander. In this study, oxygen saturation of hemoglobin solution, red blood cell suspension and artificial blood substitute under various conditions were measured by yeast-consuming-oxygen experiments instead of spectrophotometer. The empirical results were assigned into training feedforward back-propagation neural ...

The effect of measurement error in pH, PCO2, and PO2 on mathematically derived variables of oxygen transport in patients was delineated by comparing calculated oxygen saturations from a blood-gas machine with measured saturations from a CO-oximeter and further by modeling the error in a computer simulation. Twenty-one critically ill patients ...

Near-infrared spectroscopy may allow continuous and noninvasive monitoring of regional brain hemoglobin oxygen saturation by measuring the differential absorption of infrared light by oxyhemoglobin and deoxyhemoglobin. We have previously examined the correlation between the spectroscopic signal generated by a prototype cerebral oximeter (Invos 3100; Somanetics, Troy, MI), and global brain ...

STUDY OBJECTIVE: Hemoglobin-based oxygen carrier 201 (HBOC-201) is a polymerized hemoglobin of bovine origin being developed for use in hemorrhage during surgery or trauma. Pulse oximetry is commonly used in clinical practice to assess percent saturation of hemoglobin (Spo2). The ability to measure Spo2 in the presence of HBOC-201 will ...

Cerebral oximeters based on near-infrared spectroscopy may provide a continuous, noninvasive assessment of cerebral oxygenation. We evaluated a prototype cerebral oximeter (Invos 3100; Somanetics, Troy, MI) in 22 conscious, healthy volunteers breathing hypoxic gas mixtures. Using the first 12 subjects (training group), we developed an algorithm based on the mathematic ...

This study looked at the problem of the excessive variability in oxygenator testing results, induced by variation of inlet parameters, particularly of inlet oxyhaemoglobin saturation. The investigation was carried out in the laboratory. An in vitro circuit was used to perfuse a small oxygenating cell. Blood flow rate (BFR) and ...

A consistent set of definitions is given of the principal quantities pertaining to the oxygen transport by the blood, and of their mutual relationships, in relation to the methods used in their measurement. At the core is the correct definition of oxygen saturation, the deviation of which has recently been ...

Research has demonstrated that much of the mortality and morbidity in severely head-injured patients is due to secondary injury. The development of techniques to monitor cerebral blood flow, arteriovenous difference of oxygen or saturation of jugular venous blood flow with oxygen, and cerebral metabolic rate of oxygen has led to ...

The aims of this research were (a) to evaluate the validity of pulse oximetry as a criterion of tissue oxygenation for nurses to use during ventilator weaning in adult open heart surgery patients, (b) determine which measure of tissue oxygenation (via pulse oximeter or arterial blood gas analyzer) is most ...

With the advent of near-infrared spectroscopy (NIRS), it has become possible for the first time to make continuous measurements of in vivo cerebral oxygenation and hemodynamic changes at the bedside, in the intensive care unit, and in the operating room. NIRS has shown immense potential as a noninvasive technique for ...

The present study applies near infrared spectroscopy (NIRS) to the haemodynamics of the pedal circulation in normal and laminitic horses. NIRS is a noninvasive technique which uses changes in light absorption at 4 wavelengths to provide information on the changes in cytochrome aa3 (cyt aa3) reduction-oxidation (redox) status, and changes ...

BACKGROUND: The application of phase-modulated near-infrared techniques for measurement of the oxygen saturation of cerebral tissue requires both validation by conventional measures of cerebral oxygenation and determination of normal and abnormal values. This study was undertaken to validate phase-modulated near-infrared measurements of cerebral oxygen saturation by comparing them with electroencephalographic ...

Counter-current exchange of oxygen may occur between inflow and outflow microvessels of the small intestine and greatly influence the dominant sites of tissue oxygenation. To determine the location and magnitude of potential exchange, percent saturation of hemoglobin with oxygen (%SHb) was measured in microvessels throughout the intestine of rats and ...

OBJECTIVES: Several substances may be released from ischemic tissues with the declamping shock that occurs during abdominal aortic aneurysm surgery. To clarify the relationship between tissue ischemia and venous endothelin-1 (ET-1) level in humans, plasma ET-1 and oxygen content in the iliac vein were measured before anesthesia, after the induction ...

Using transcranial cerebral oximetry, we monitored 30 patients who underwent cerebral angiography by the femoral route. Transcranial cerebral oximetry is a noninvasive technique of regional cerebral oxygen saturation measurement that uses near-infrared spectroscopy to differentiate oxyhemoglobin from reduced hemoglobin. Needle puncture, catheterization, and contrast media injection produced no significant peak ...