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At least 73 records · Page 4Linked to original sources
PubMed2003

A new method for the measurement of cerebral blood volume and total circulating blood volume using near infrared spatially resolved spectroscopy and indocyanine green: application and validation in neonates.

A new technique known as tissue dye densitometry (TDD) has been developed to simultaneously measure cerebral blood volume (CBV) and total circulating blood volume (TCV) using near infrared (NIR) spatially resolved spectroscopy (SRS) and the injection of indocyanine green (ICG). Using a medical NIR spectrometer with SRS capability (NIRO-300, Hamamatsu KK), a new parameter is calculated known as the ICG Hb index (IHI), which represents the ratio of ICG concentration to Hb concentration in tissue. Acting as a tracer, ICG is cleared by the liver over 15 min, providing a change of tracer concentration (DeltaCICG,tis), which allows the calculation of the total Hb concentration in tissue (tcHb) using the equation: tcHbtis (micro molar) = DeltaCICG,tis/DeltaIHI. The CBV can subsequently be calculated from tcHbtis given the absolute Hb concentration in blood (g/dL), from which the ICG concentration in blood (DeltaCICG,bl) is obtained. By back-extrapolating the DeltaCICG,bl curve to the peak time, the initial ICG concentration in tissue blood (C0ICG,bl) can be found and TCV can then be calculated. The TCV of 17 neonates were measured using the TDD technique and for comparison using the previously reported fetal Hb dilution technique (FHD). The mean TCV measured by the FHD and TDD techniques were 70.19 +/- 13.73 mL/kg and 70.80 +/- 32.54 mL/kg. The Bland Altman plot showed that the bias was 0.61 +/- 34.34 mL/kg and limits of agreement (2 SD) were -68.07 mL/kg and 69.30 mL/kg. The agreement is limited and the TDD technique needs further validation and development for use in a clinical environment.

Blood Transfusion↗
PubMed2001

Pulse dye densitometry: a novel bedside monitor of circulating blood volume.

INTRODUCTION: Monitoring of circulating blood volume is important in the management of critically ill patients. Current methods of circulating blood volume measurements such as indicator dilution using radioisotopes or Evans blue dye are unsuitable for clinical application as these tests do not allow for frequent repeated measurements to be done. A direct bedside measurement of circulating blood volume using the principle of pulse dye densitometry was recently introduced. This is essentially an indicator dilution technique using indocyanine green combined with the principle of pulse spectrophotometry. METHODS: This paper aims to review this method of circulating blood volume measurement and provide a summary of the published clinical trials that compared its accuracy with the other conventional methods of circulating blood volume measurement, based on a Medline search, spanning the period 1966 to August 2000. RESULTS: Published studies show that pulse dye densitometry gives comparable results when compared to other conventional methods of blood volume measurement. Its ability to measure circulating blood volume accurately and repeatedly, as frequently as every 20 min makes it suitable for clinical application. CONCLUSION: Pulse dye densitometry provides for a rapid, semi-noninvasive and convenient bedside assessment of circulating blood volume that is applicable clinically. Further studies are needed to ascertain the impact of the use of pulse dye densitometry on the mortality and morbidity of the critically ill.

Blood Circulation↗
PubMed1983

[Glucose metabolism in trauma-induced brain edema, with special reference to local blood circulation and blood-brain barrier].

Local cerebral glucose utilization (LCGU) was studied using the carbon 14-deoxyglucose method in rats with local freezing lesion in the left parietal cortex. A depression of LCGU developed with time after the lesion, being most prominent throughout the cortical areas of the lesioned hemisphere 3 days after lesion. Corresponding results in other regions were contralateral cortical areas, ipsilateral and contralateral subcortical structures. Brain stem structures were not affected. In white matter bilateral depression of LCGU reached its peak 24 hours after the lesion. LCGU returned to normal within 5 days in all affected areas. The areas affected and the time-course of the observed changes did not correlate with the location and known time-course of development of cerebral edema. Local cerebral blood flow (LCBF) was measured 1 and 3 days after a freezing lesion using the carbon 14-iodoantipyrine method. Twenty-four hours after a freezing lesion normal LCBF were seen throughout the traumatized brain. Three days after the lesion an increased LCBF involved all cortical areas, with the hyperemia being more pronounced in the hemisphere contralateral to the lesion. No corresponding changes in LCBF were observed. Evans blue dye was injected intravenously before the start of the barrier (BBB) at each time period following the lesion could be determined. Blue staining was seen in the area of the lesion in all animals killed 4 or 24 hrs after the lesion was made, indicating a BBB permeable to the Evans blue-serum protein complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗