Fluorescent microspheres to measure organ perfusion: validation of a simplified sample processing technique

1995 ◽  
Vol 269 (2) ◽  
pp. H725-H733 ◽  
Author(s):  
M. F. Van Oosterhout ◽  
H. M. Willigers ◽  
R. S. Reneman ◽  
F. W. Prinzen
Keyword(s):  
Blood Flow ◽  
Coronary Artery Stenosis ◽  
Processing Technique ◽  
Processing Method ◽  
Organ Perfusion ◽  
Sample Processing ◽  
Fluorescent Microspheres ◽  
Fluorescent Microsphere ◽  
Gamma Counting ◽  
Anesthetized Dogs

A disadvantage of nonradioactive microsphere techniques is that the processing of samples is time-consuming and complex. We developed and validated a simplified processing method for the fluorescent microsphere (FM) technique. In seven anesthetized dogs with coronary artery stenosis up to six different FM and five different radioactivity labeled microspheres (RM) were injected. Two FM and two RM labels were injected simultaneously to enable inter- and intramethod comparison. After gamma-counting samples of blood, myocardium (n = 168), and other organs (n = 59) were digested in test tubes with 2 N ethanolic KOH (60 degrees C, 48 h), microspheres were sedimented by centrifugation, dye was extracted in the same tube, and fluorescence was measured. With this processing method, recovery of FM was approximately 100%. Good correlations for inter- and intramethod comparisons were found [r = 0.985 +/- 0.01 (mean +/- SD)]. The lower intermethod correlation for blue microspheres (r = 0.958) indicates that the use of this label is less desirable. RM and FM endocardial-to-epicardial blood flow ratios correlated well (r = 0.974). With this one-vessel centrifugal sedimentation method and at least five fluorescently labeled microspheres, blood flow can be reliably measured in various organs, including ischemic myocardium.

Fetal sheep adrenal blood flow responses to hypoxemia after splanchnicotomy using fluorescent microspheres

1998 ◽  
Vol 84 (1) ◽  
pp. 82-89 ◽  
Author(s):  
Lynn F. Buchwalder ◽  
Michelle Lin ◽  
Thomas J. McDonald ◽  
Peter W. Nathanielsz
Keyword(s):  
Blood Flow ◽  
Splanchnic Nerve ◽  
Radioactive Microspheres ◽  
Fluorescent Microspheres ◽  
Nerve Section ◽  
Fetal Sheep ◽  
Blood Samples ◽  
Fluorescent Microsphere ◽  
Cont Group ◽  
And Control

Buchwalder, Lynn F., Michelle Lin, Thomas J. McDonald, and Peter W. Nathanielsz. Fetal sheep adrenal blood flow responses to hypoxemia after splanchnicotomy using fluorescent microspheres. J. Appl. Physiol. 84(1): 82–89, 1998.—Adrenal gland blood flow (ABF) increases during hypoxemia in fetal sheep, but regulation of ABF is poorly understood. The purpose of this study was to determine the effects of splanchnic nerve section on fetal ABF responses to hypoxemia using the fluorescent microsphere (FM) technique. At 125 days of gestation, 14 unanesthetized fetal sheep [bilateral splanchnicotomy (Splx, n = 6) and control (Cont, n = 8)] were injected with FM before and at 60 min of N2-induced hypoxemia (∼40% decrease in fetal arterial [Formula: see text]). Adrenal tissue and reference blood samples were digested and filtered, and FM dye was extracted for spectrometer analysis. Baseline whole, medullary, and cortical ABF for the Cont group were similar to published values using radioactive microspheres and did not differ from Splx values. Hypoxemia increased whole, medullary, and cortical ABF (mean ± SE) from baseline for the Cont group by 281 ± 35, 258 ± 31, and 496 ± 81% ( P < 0.05). The increase for the Splx group was attenuated compared with the Cont group ( P < 0.05) for whole and medullary ABF (139 ± 27 and 43 ± 27%) but not cortical ABF (326 ± 91%). We conclude that 1) the FM technique is valid for measuring fetal ABF and 2) in fetal sheep the splanchnic nerve is not necessary to maintain basal ABF but plays an important role in regulating the hypoxemia-induced increase in ABF through the medullary, but not cortical, ABF response.

Spatial distribution of venous gas emboli in the lungs

1999 ◽  
Vol 87 (5) ◽  
pp. 1937-1947 ◽  
Author(s):  
Jennifer E. Souders ◽  
Jeffrey B. Doshier ◽  
Nayak L. Polissar ◽  
Michael P. Hlastala
Keyword(s):  
Blood Flow ◽  
Spatial Distribution ◽  
Pulmonary Blood Flow ◽  
Flow Dynamics ◽  
Pulmonary Vasculature ◽  
Pulmonary Emboli ◽  
Fluorescent Microspheres ◽  
Spatial Coordinates ◽  
Anesthetized Dogs ◽  
Baseline Flow

The distribution of gaseous pulmonary emboli is presumed to be determined by their buoyancy. We hypothesized that regional pulmonary blood flow may also influence their distribution. Therefore, pulmonary blood flow was measured in supine, anesthetized dogs with use of 15-μm fluorescent microspheres at baseline and during N2 embolism. The animals were killed, and the lungs were excised, air-dried, and diced into ∼2-cm3 pieces with weights and spatial coordinates recorded. Embolism was defined as a >10% flow decrease relative to baseline. Vertically, the incidence of embolism increased substantially by 6 ± 1% per additional centimeter in height compared with baseline ( P = 0.0003). Embolism also increased radially by 3 ± 1%/cm from the hilum ( P = 0.002). There was a weaker but statistically significant increase in embolism to pieces with greater baseline flow, 9 ± 2% for every 1.0 increase in relative baseline flow ( P = 0.008). We conclude that the distribution of gaseous emboli is influenced by buoyancy and flow dynamics within the pulmonary vasculature.

Dopamine-1 receptor stimulation impairs intestinal oxygen utilization during critical hypoperfusion

2003 ◽  
Vol 284 (2) ◽  
pp. H668-H675 ◽  
Author(s):  
Jorge A. Guzman ◽  
Ariosto E. Rosado ◽  
James A. Kruse
Keyword(s):  
Blood Flow ◽  
Mucosal Blood Flow ◽  
Control Group ◽  
Oxygen Utilization ◽  
Hemorrhage Control ◽  
Receptor Stimulation ◽  
Anesthetized Dogs ◽  
Group 2 ◽  
Increased Susceptibility ◽  
Group 1

Effects of a dopamine-1 (DA-1) receptor agonist on systemic and intestinal oxygen delivery (D˙o 2)-uptake relationships were studied in anesthetized dogs during sequential hemorrhage. Control ( group 1) and experimental animals ( group 2) were treated similarly except for the addition of fenoldopam (1.0 μg · kg−1 · min−1) in group 2. Both groups had comparable systemic criticalD˙o 2(D˙o 2crit), but animals in group 2 had a higher gut D˙o 2crit(1.12 ± 1.13 vs. 0.80 ± 0.09 ml · kg−1 · min−1, P < 0.05). At the mucosal level, a clear biphasic delivery-uptake relationship was not observed in group 1; thus oxygen consumption by the mucosa may be supply dependent under physiological conditions. Group 2 demonstrated higher peak mucosal blood flow and lack of supply dependency at higher mucosalD˙o 2 levels. Fenoldopam resulted in a more conspicuous biphasic relationship at the mucosa and a rightward shift of overall splanchnic D˙o 2crit despite increased splanchnic blood flow. These findings suggest that DA-1 receptor stimulation results in increased gut perfusion heterogeneity and maldistribution of perfusion, resulting in increased susceptibility to ischemia.

Backscatter Coefficient Measurements Using a Reference Phantom to Extract Depth-Dependent Instrumentation Factors

1990 ◽  
Vol 12 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Lin Xin Yao ◽  
James A. Zagzebski ◽  
Ernest L. Madsen
Keyword(s):  
Attenuation Coefficient ◽  
Time Domain ◽  
Reduction Method ◽  
Processing Technique ◽  
Processing Method ◽  
Backscatter Coefficient ◽  
Attenuation Coefficients ◽  
Reference Phantom ◽  
Dependent Signal ◽  
Data Reduction Method

In previous work, we demonstrated that accurate backscatter coefficient measurements are obtained with a data reduction method that explicitly accounts for experimental factors involved in recording echo data. An alternative, relative processing method for determining the backscatter coefficient and the attenuation coefficient is presented here. This method involves comparison of echo data from a sample with data recorded from a reference phantom whose backscatter and attenuation coefficients are known. A time domain processing technique is used to extract depth and frequency dependent signal ratios for the sample and the reference phantom. The attenuation coefficient and backscatter coefficient of the sample are found from these ratios. The method is tested using tissue-mimicking phantoms with known scattering and attenuation properties.

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