scholarly journals Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation

2021 ◽  
Author(s):  
Michael C. Kolios ◽  
Eno Hysi ◽  
Ratan K. Saha
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Frequency Domain Analysis ◽  
Spectral Slope ◽  
Spectral Parameters ◽  
Oxygen Saturation Level ◽  
Oxygenation Level ◽  
Rbc Aggregation

Red blood cell (RBC) aggregation and oxygenation are important markers for a variety of blood disorders. No current technique is capable of simultaneously measuring aggregation/oxygenation levels noninvasively. We propose using photoacoustic ultrasound spectroscopy (PAUS) for assessing both phenomena. This technique relies on frequency-domain analysis of the PA signals by extracting parameters such as the ultrasound spectral slope and the midband fit. To investigate the effect of hematocrit, aggregation, and oxygenation levels on PAUS parameters, a Monte Carlo-based theoretical model and an experimental protocol using porcine RBCs were developed. The samples were illuminated at 750 and 1064 nm and changes in the PAUS parameters were compared to the oxygen-dependent optical absorption coefficients to assess the oxygenation level. Good agreement between the theoretical and experimental spectral parameters was obtained for the spectral slope of the nonaggregated spectra (∼0.3  dB/MHz∼0.3  dB/MHz). The experimental midband fit increased by ∼5  dB∼5  dB for the largest aggregate size. Based on the analysis of the PA signals, the oxygen saturation level of the most aggregated sample was >20%>20% greater than the nonaggregated sample. The results provide a framework for using PA signals’ spectroscopic parameters for monitoring the aggregation and oxygenation levels of RBCs.

scholarly journals Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation

2021 ◽  
Author(s):  
Michael C. Kolios
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Frequency Domain Analysis ◽  
Spectral Slope ◽  
Spectral Parameters ◽  
Oxygen Saturation Level ◽  
Oxygenation Level ◽  
Rbc Aggregation

Red blood cell (RBC) aggregation and oxygenation are important markers for a variety of blood disorders. No current technique is capable of simultaneously measuring aggregation/oxygenation levels noninvasively. We propose using photoacoustic ultrasound spectroscopy (PAUS) for assessing both phenomena. This technique relies on frequency-domain analysis of the PA signals by extracting parameters such as the ultrasound spectral slope and the midband fit. To investigate the effect of hematocrit, aggregation, and oxygenation levels on PAUS parameters, a Monte Carlo-based theoretical model and an experimental protocol using porcine RBCs were developed. The samples were illuminated at 750 and 1064 nm and changes in the PAUS parameters were compared to the oxygen-dependent optical absorption coefficients to assess the oxygenation level. Good agreement between the theoretical and experimental spectral parameters was obtained for the spectral slope of the nonaggregated spectra (∼0.3  dB/MHz∼0.3  dB/MHz). The experimental midband fit increased by ∼5  dB∼5  dB for the largest aggregate size. Based on the analysis of the PA signals, the oxygen saturation level of the most aggregated sample was >20%>20% greater than the nonaggregated sample. The results provide a framework for using PA signals’ spectroscopic parameters for monitoring the aggregation and oxygenation levels of RBCs.

scholarly journals Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation

2021 ◽  
Author(s):  
Michael C. Kolios
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Frequency Domain Analysis ◽  
Spectral Slope ◽  
Spectral Parameters ◽  
Oxygen Saturation Level ◽  
Oxygenation Level ◽  
Rbc Aggregation

Red blood cell (RBC) aggregation and oxygenation are important markers for a variety of blood disorders. No current technique is capable of simultaneously measuring aggregation/oxygenation levels noninvasively. We propose using photoacoustic ultrasound spectroscopy (PAUS) for assessing both phenomena. This technique relies on frequency-domain analysis of the PA signals by extracting parameters such as the ultrasound spectral slope and the midband fit. To investigate the effect of hematocrit, aggregation, and oxygenation levels on PAUS parameters, a Monte Carlo-based theoretical model and an experimental protocol using porcine RBCs were developed. The samples were illuminated at 750 and 1064 nm and changes in the PAUS parameters were compared to the oxygen-dependent optical absorption coefficients to assess the oxygenation level. Good agreement between the theoretical and experimental spectral parameters was obtained for the spectral slope of the nonaggregated spectra (∼0.3  dB/MHz∼0.3  dB/MHz). The experimental midband fit increased by ∼5  dB∼5  dB for the largest aggregate size. Based on the analysis of the PA signals, the oxygen saturation level of the most aggregated sample was >20%>20% greater than the nonaggregated sample. The results provide a framework for using PA signals’ spectroscopic parameters for monitoring the aggregation and oxygenation levels of RBCs.

scholarly journals Photoacoustic Detection of Red Blood Cell Aggregation

2021 ◽  
Author(s):  
Eno Hysi
Keyword(s):  
Blood Cell ◽  
Oxygen Saturation ◽  
Red Blood Cell ◽  
Photoacoustic Imaging ◽  
Power Spectra ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Spectral Slope ◽  
Photoacoustic Detection ◽  
Rbc Aggregation

The potential of photoacoustic imaging for detecting red blood cell (RBC) aggregation is explored. Enhanced aggregation is observed in disorders such as diabetes impairing oxygen release into tissue. Simultaneous measurements of aggregation and oxygenation levels cannot be made using current tools. Photoacoustic detection of aggregation and assessment of oxygen saturation was investigated. A theoretical and experimental model of aggregation was developed using human and porcine RBCs. Frequency-domain analysis of the PA signals was used to derive the spectral slope and midband fit of the normalized power spectra for various hematorit and aggregation conditions. Oxygen saturation was assessed using multiple wavelengths of illumination. The experimental spectral slope (~0.3 dB/MHz) for non-aggregated samples agreed with the theory decreasing with increasing aggregate size. The midband fit increased by ~5 dB when the aggregate size reached the largest level while the oxygen saturation increased by > 20%. These results suggest that photoacoustic-radio-frequency-spectroscopic-parameters have the potential to monitor RBC aggregation and oxygenation level.

scholarly journals Photoacoustic Detection of Red Blood Cell Aggregation

2021 ◽  
Author(s):  
Eno Hysi
Keyword(s):  
Blood Cell ◽  
Oxygen Saturation ◽  
Red Blood Cell ◽  
Photoacoustic Imaging ◽  
Power Spectra ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Spectral Slope ◽  
Photoacoustic Detection ◽  
Rbc Aggregation

The potential of photoacoustic imaging for detecting red blood cell (RBC) aggregation is explored. Enhanced aggregation is observed in disorders such as diabetes impairing oxygen release into tissue. Simultaneous measurements of aggregation and oxygenation levels cannot be made using current tools. Photoacoustic detection of aggregation and assessment of oxygen saturation was investigated. A theoretical and experimental model of aggregation was developed using human and porcine RBCs. Frequency-domain analysis of the PA signals was used to derive the spectral slope and midband fit of the normalized power spectra for various hematorit and aggregation conditions. Oxygen saturation was assessed using multiple wavelengths of illumination. The experimental spectral slope (~0.3 dB/MHz) for non-aggregated samples agreed with the theory decreasing with increasing aggregate size. The midband fit increased by ~5 dB when the aggregate size reached the largest level while the oxygen saturation increased by > 20%. These results suggest that photoacoustic-radio-frequency-spectroscopic-parameters have the potential to monitor RBC aggregation and oxygenation level.

scholarly journals On the use of photoacoustics to detect red blood cell aggregation

2021 ◽  
Author(s):  
Michael C. Kolios
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Spectral Power ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Dominant Frequency ◽  
Red Blood Cell Aggregation ◽  
Theoretical Predictions ◽  
Rbc Aggregation ◽  
Simulation Results

The feasibility of detecting red blood cell (RBC) aggregation with photoacoustics (PAs) was investigated theoretically and experimentally using human and porcine RBCs. The theoretical PA signals and spectra generated from such samples were examined for several hematocrit levels and aggregates sizes. The effect of a finite transducer bandwidth on the received PA signal was also examined. The simulation results suggest that the dominant frequency of the PA signals from non-aggregated RBCs decreases towards clinical frequency ranges as the aggregate size increases. The experimentally measured mean spectral power increased by ~6 dB for the largest aggregate compared to the non-aggregated samples. Such results confirm the theoretical predictions and illustrate the potential of using PA imaging for detecting RBC aggregation.

Parameters of red blood cell aggregation as correlates of the inflammatory state

2001 ◽  
Vol 280 (5) ◽  
pp. H1982-H1988 ◽  
Author(s):  
R. Ben Ami ◽  
G. Barshtein ◽  
D. Zeltser ◽  
Y. Goldberg ◽  
I. Shapira ◽  
...  
Keyword(s):  
Shear Stress ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Aggregate Fraction ◽  
Plasma Factor ◽  
Cellular Factors ◽  
Rbc Aggregation ◽  
Aggregation Parameters

To identify clinically relevant parameters of red blood cell (RBC) aggregation, we examined correlations of aggregation parameters with C-reactive protein and fibrinogen in unstable angina (UA), acute myocardial infarction (AMI), and bacterial infection (BI). Aggregation parameters were derived from the distribution of RBC population into aggregate sizes (cells per aggregate) and changing of the distribution by flow-derived shear stress. Increased aggregation was observed in the following order: UA, AMI, and BI. The best correlation was obtained by integration of large aggregate fraction as a function of shear stress. To differentiate plasmatic from cellular factors in RBC aggregation, we determined the aggregation in the presence and absence of plasma and formulated a “plasma factor” (PF) ranging from 0 to 1. In AMI the enhanced aggregation was entirely due to PF (PF = 1), whereas in UA and BI it was due to both plasmatic and cellular factors (0 ≤ PF ≤ 1). It is proposed that clinically relevant parameters of RBC aggregation should express both RBC aggregate size distribution and aggregate resistance to disaggregation and distinguish between plasmatic and cellular factors.

scholarly journals On the use of photoacoustics to detect red blood cell aggregation

2021 ◽  
Author(s):  
Michael C. Kolios
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Spectral Power ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Dominant Frequency ◽  
Red Blood Cell Aggregation ◽  
Theoretical Predictions ◽  
Rbc Aggregation ◽  
Simulation Results

The feasibility of detecting red blood cell (RBC) aggregation with photoacoustics (PAs) was investigated theoretically and experimentally using human and porcine RBCs. The theoretical PA signals and spectra generated from such samples were examined for several hematocrit levels and aggregates sizes. The effect of a finite transducer bandwidth on the received PA signal was also examined. The simulation results suggest that the dominant frequency of the PA signals from non-aggregated RBCs decreases towards clinical frequency ranges as the aggregate size increases. The experimentally measured mean spectral power increased by ~6 dB for the largest aggregate compared to the non-aggregated samples. Such results confirm the theoretical predictions and illustrate the potential of using PA imaging for detecting RBC aggregation.

Modulation of endothelial nitric oxide synthase expression by red blood cell aggregation

2004 ◽  
Vol 286 (1) ◽  
pp. H222-H229 ◽  
Author(s):  
Oguz K. Baskurt ◽  
Ozlem Yalcin ◽  
Sadi Ozdem ◽  
Jonathan K. Armstrong ◽  
Herbert J. Meiselman
Keyword(s):  
Nitric Oxide ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Aggregation ◽  
Shear Stresses ◽  
Control Mechanisms ◽  
Vascular Control ◽  
Arterial Blood ◽  
Rbc Aggregation ◽  
Endothelial Nitric Oxide

The effects of enhanced red blood cell (RBC) aggregation on nitric oxide (NO)-dependent vascular control mechanisms have been investigated in a rat exchange transfusion model. RBC aggregation for cells in native plasma was increased via a novel method using RBCs covalently coated with a 13-kDa poloxamer copolymer (Pluronic F-98); control experiments used RBCs coated with a nonaggregating 8.4-kDa poloxamer (Pluronic F-68). Rats exchange transfused with aggregating RBC suspensions demonstrated significantly enhanced RBC aggregation throughout the 5-day follow-up period, with mean arterial blood pressure increasing gradually over this period. Arterial segments (≈300 μm in diameter) were isolated from gracilis muscle on the fifth day and mounted between two glass micropipettes in a special chamber equipped with pressure servo-control system. Dose-dependent dilation by ACh and flow-mediated dilation of arterial segments pressurized to 30 mmHg and preconstricted to 45–55% of the original diameter by phenylephrine were significantly blunted in rats with enhanced RBC aggregation. Both responses were totally abolished by nonspecific NO synthase (NOS) inhibitor ( Nω-nitro-l-arginine methyl ester) treatment of arterial segments, indicating that the responses were NO related. Additionally, expression of endothelial NOS protein was found to be decreased in muscle samples obtained from rats exchanged with aggregating cell suspensions. These results imply that enhanced RBC aggregation results in suppressed expression of NO synthesizing mechanisms, thereby leading to altered vasomotor tonus; the mechanisms involved most likely relate to decreased wall shear stresses due to decreased blood flow and/or increased axial accumulation of RBCs.

Effects of red blood cell aggregation on myocardial hematocrit gradient using two approaches to increase aggregation

2006 ◽  
Vol 290 (2) ◽  
pp. H765-H771 ◽  
Author(s):  
Ozlem Yalcin ◽  
Funda Aydin ◽  
Pinar Ulker ◽  
Mehmet Uyuklu ◽  
Firat Gungor ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Control Level ◽  
Three Dimensional ◽  
Cell Aggregation ◽  
Plasma Viscosity ◽  
Covalent Attachment ◽  
Erythrocyte Aggregation ◽  
Rbc Aggregation ◽  
A New Technique

The normal transmyocardial tissue hematocrit distribution (i.e., subepicardial greater than subendocardial) is known to be affected by red blood cell (RBC) aggregation. Prior studies employing the use of infused large macromolecules to increase erythrocyte aggregation are complicated by both increased plasma viscosity and dilution of plasma. Using a new technique to specifically alter the aggregation behavior by covalent attachment of Pluronic F-98 to the surface of the RBC, we have determined the effects of only enhanced aggregation (i.e., Pluronic F-98-coated RBCs) versus enhanced aggregation with increased plasma viscosity (i.e., an addition of 500 kDa dextran) on myocardial tissue hematocrit in rapidly frozen guinea pig hearts. Although both approaches equally increased aggregation, tissue hematocrit profiles differed markedly: 1) when Pluronic F-98-coated cells were used, the normal transmyocardial gradient was abolished, and 2) when dextran was added, the hematocrit remained at subepicardial levels for about one-half the thickness of the myocardium and then rapidly decreased to the control level in the subendocardial layer. Our results indicate that myocardial hematocrit profiles are sensitive to both RBC aggregation and to changes of plasma viscosity associated with increased RBC aggregation. Furthermore, they suggest the need for additional studies to explore the mechanisms affecting RBC distribution in three-dimensional vascular beds.

scholarly journals Red blood cell (RBC) aggregation and its influence on non-Newtonian nature of blood in microvasculature

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Chitra Murali ◽  
Perumal Nithiarasu
Keyword(s):  
Blood Flow ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Aggregation ◽  
Time Dependent ◽  
Shear Rates ◽  
Red Blood Cell Aggregation ◽  
Significant Difference ◽  
Rbc Aggregation ◽  
Rouleaux Formation

AbstractA robust computational model is proposed to investigate the non-Newtonian nature of blood flow due to rouleaux formation in microvasculature. The model consists of appropriate forces responsible for red blood cell (RBC) aggregation in the microvasculature, tracking of RBCs, and coupling between plasma flow and RBCs. The RBC aggregation results have been compared against the available data. The importance of different hydrodynamic forces on red blood cell aggregation has been delineated by comparing the time dependent path of the RBCs. The rheological changes to the blood flow have been investigated under different shear rates and hematocrit values and quantified with and without RBC aggregation. The results obtained in terms of wall shear stress (WSS) and blood viscosity indicate a significant difference between Newtonian and powerlaw fluid assumptions.

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