Phosphorescence quenching and the microcirculation: An automated, multipoint oxygen tension measuring instrument

1995 ◽  
Vol 66 (10) ◽  
pp. 5075-5084 ◽  
Author(s):  
Ross D. Shonat ◽  
Keith N. Richmond ◽  
Paul C. Johnson
Keyword(s):  
Oxygen Tension ◽  
Measuring Instrument ◽  
Phosphorescence Quenching

Erythrocyte-associated transients in capillary Po2: an isovolemic hemodilution study in the rat spinotrapezius muscle

2007 ◽  
Vol 292 (5) ◽  
pp. H2540-H2549 ◽  
Author(s):  
Matthew C. Barker ◽  
Aleksander S. Golub ◽  
Roland N. Pittman
Keyword(s):  
Blood Flow ◽  
Oxygen Tension ◽  
Oxygen Delivery ◽  
Capillary Number ◽  
Observation Point ◽  
Isovolemic Hemodilution ◽  
Phosphorescence Quenching ◽  
Mathematical Simulations ◽  
The Impact ◽  
532 Nm

Mathematical simulations of oxygen delivery to tissue from capillaries that take into account the particulate nature of blood flow predict the existence of oxygen tension (Po2) gradients between erythrocytes (RBCs). As RBCs and plasma alternately pass an observation point, these gradients are manifested as rapid fluctuations in Po2, also known as erythrocyte-associated transients (EATs). The impact of hemodilution on EATs and oxygen delivery at the capillary level of the microcirculation has yet to be elucidated. Therefore, in the present study, phosphorescence quenching microscopy was used to measure EATs and Po2 in capillaries of the rat spinotrapezius muscle at the following systemic hematocrits (Hctsys): normal (39%) and after moderate (HES1; 27%) or severe (HES2; 15%) isovolemic hemodilution using a 6% hetastarch solution. A 532-nm laser, generating 10-μs pulses concentrated onto a 0.9-μm spot, was used to obtain plasma Po2 values 100 times/s at points along surface capillaries of the muscle. Mean capillary Po2 (Pc[Formula: see text]; means ± SE) significantly decreased between conditions (normal: 56 ± 2 mmHg, n = 45; HES1: 47 ± 2 mmHg, n = 62; HES2: 27 ± 2 mmHg, n = 52, where n = capillary number). In addition, the magnitude of Po2 transients (ΔPo2) significantly decreased with hemodilution (normal: 19 ± 1 mmHg, n = 45; HES1: 11 ± 1 mmHg, n = 62; HES2: 6 ± 1 mmHg, n = 52). Results suggest that the decrease in Pc[Formula: see text] and ΔPo2 with hemodilution is primarily dependent on Hctsys and subsequent microvascular compensations.

Oxygen tension gradients and heterogeneity in venous microcirculation: a phosphorescence quenching study

1997 ◽  
Vol 272 (5) ◽  
pp. H2233-H2240 ◽  
Author(s):  
R. D. Shonat ◽  
P. C. Johnson
Keyword(s):  
Blood Pressure ◽  
Oxygen Tension ◽  
Systemic Blood Pressure ◽  
Systemic Blood ◽  
Microvascular Network ◽  
Waste Products ◽  
Phosphorescence Quenching ◽  
Oxygen Gradients ◽  
Weakly Dependent ◽  
Made In

Localized measurements of intravascular oxygen tension (PO2) at multiple locations in the microvascular network of the rat spinotrapezius muscle were used to study the spatial distribution of PO2 in venular structures. By use of a newly developed phosphorescence system to rapidly and repeatedly measure PO2, 538 individual measurements were made in 18 different networks during rest. Average intravascular PO2 was (in mmHg +/- SD) 33 +/- 9, 21 +/- 9, 26 +/- 10, and 33 +/- 8 in small arcade arterioles, postcapillary venules (PV), 3 degrees venules (3V), and arcade venules, respectively. The coefficient of variation (CV), a descriptive indicator of spatial heterogeneity, was correspondingly 0.28, 0.45, 0.37, and 0.23 for the different vessel groups. PO2 was found to increase significantly (P < 0.001) from PV to 3V, rising 0.009 +/- 0.002 mmHg/microns along the vessel. By linear regression, the slope of PO2 for the vessel difference group, PV-3V as a function of mean systemic blood pressure (BPm; in mmHg) was -0.09 +/- 0.04 (P < 0.05), indicating that the measured longitudinal oxygen gradients and CV are only weakly dependent on BPm. The results support the hypothesis that oxygen can diffuse across the walls of postcapillary vessels and suggest that the venular structures are not merely passive conduits for removing oxygen and waste products but may play an important role in regulating oxygen delivery.

scholarly journals Microvascular oxygen tension in the rat mesentery

2008 ◽  
Vol 294 (1) ◽  
pp. H21-H28 ◽  
Author(s):  
Aleksander S. Golub ◽  
Matthew C. Barker ◽  
Roland N. Pittman
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Tension ◽  
Oxygen Delivery ◽  
Vascular Wall ◽  
Spot Size ◽  
Vessel Diameter ◽  
Primary Site ◽  
Phosphorescence Quenching ◽  
Rat Mesentery ◽  
Mesenteric Microcirculation

Longitudinal Po2 profiles in the microvasculature of the rat mesentery were studied using a novel phosphorescence quenching microscopy technique that minimizes the accumulated photoconsumption of oxygen by the method. Intravascular oxygen tension (Po2, in mmHg) and vessel diameter ( d, in μm) were measured in mesenteric microvessels ( n = 204) of seven anesthetized rats (275 g). The excitation parameters were as follows: 7 × 7-μm spot size; 410 nm laser; and 100 curves at 11 pulses/s, with pulse parameters of 2-μs duration and 80-pJ/μm2 energy density. The mean Po2 (± SE) was 65.0 ± 1.4 mmHg ( n = 78) for arterioles ( d = 18.8 ± 0.7 μm), 62.1 ± 2.0 mmHg ( n = 38) at the arteriolar end of capillaries ( d = 7.8 ± 0.3 μm), and 52.0 ± 1.0 mmHg ( n = 88) for venules ( d = 22.5 ± 1.0 μm). There was no apparent dependence of Po2 on d in arterioles and venules. There were also no significant deviations in Po2 based on d (bin width, 5 μm) from the general mean for both of these types of vessels. Results indicate that the primary site of oxygen delivery to tissue is located between the smallest arterioles and venules (change of 16.3 mmHg, P = 0.001). In conclusion, oxygen losses from mesenteric arterioles and venules are negligible, indicating low metabolic rates for both the vascular wall and the mesenteric tissue. Capillaries appear to be the primary site of oxygen delivery to the tissue in the mesenteric microcirculation. In light of the present results, previously reported data concerning oxygen consumption in the mesenteric microcirculation can be explained as artifacts of accumulated oxygen consumption due to the application of instrumentation having a large excitation area for Po2 measurements in slow moving and stationary media.

A new technique for the mapping of oxygen tension on the brain surface

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S543-S543
Author(s):  
Satoshi Kimura ◽  
Keigo Matsumoto ◽  
Yoshio Imahori ◽  
Katsuyoshi Mineura ◽  
Toshiyuki Itoh
Keyword(s):  
Oxygen Tension ◽  
New Technique ◽  
Brain Surface ◽  
A New Technique ◽  
The Brain

The Software «MMI–calibration 3.0»

Metrologiya ◽  
2020 ◽  
pp. 16-24
Author(s):  
Alexandr D. Chikmarev
Keyword(s):  
Power Series ◽  
Data Processing ◽  
Statistical Treatment ◽  
Correction Function ◽  
Calibration Function ◽  
Measuring Instrument ◽  
Working Standard ◽  
Calibration Protocol ◽  
Error Probabilities ◽  
Continuous Power

A single program has been developed to ensure that the final result of the data processing of the measurement calibration protocol is obtained under normal conditions. The calibration result contains a calibration function or a correction function in the form of a continuous sedate series and a calibration chart based on typical additive error probabilities. Solved the problem of the statistical treatment of the calibration protocol measuring in normal conditions within a single program “MMI–calibration 3.0” that includes identification of the calibration function in a continuous power series of indications of a measuring instrument and chart calibration. An example of solving the problem of calibration of the thermometer by the working standard of the 3rd grade with the help of the “MMI-calibration 3.0” program.

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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