Intravital microscopic observations of 15-μm microspheres lodging in the pulmonary microcirculation

2005 ◽  
Vol 98 (6) ◽  
pp. 2242-2248 ◽  
Author(s):  
Wayne J. E. Lamm ◽  
Susan L. Bernard ◽  
Wiltz W. Wagner ◽  
Robb W. Glenny
Keyword(s):  
Blood Flow ◽  
Flow Distribution ◽  
Lung Model ◽  
Blood Flow Distribution ◽  
Local Flow ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Perfused Lung ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Microcirculation

Vascular infusions of 15-μm-diameter microspheres are used to study pulmonary blood flow distribution. The sites of microsphere lodging and their effects on microvascular perfusion are debated but unknown. Using intravital microscopy of the subpleural surface of rat lungs, we directly observed deposition of fluorescent microspheres. In a pump-perfused lung model, ∼0.5 million microspheres were infused over 30 s into the pulmonary artery of seven rats. Microsphere lodging was analyzed for the location in the microvasculature and the effect on local flow after lodging. On average, we observed 3.2 microspheres per 160 alveolar facets. The microspheres always entered the arterioles as singlets and lodged at the inlets to capillaries, either in alveolar corner vessels or small arterioles. In all cases, blood flow continued either around the microspheres or into the capillaries via adjacent pathways. We conclude that 15-μm-diameter microspheres, in doses in excess of those used in typical studies, have no significant impact on pulmonary capillary blood flow distribution.

Measurement of pulmonary blood flow during exercise using nitrous oxide

1962 ◽  
Vol 17 (4) ◽  
pp. 579-586 ◽  
Author(s):  
Margaret R. Becklake ◽  
C. J. Varvis ◽  
L. D. Pengelly ◽  
S. Kenning ◽  
M. McGregor ◽  
...  
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Dilution Technique ◽  
Fick Principle ◽  
Pulmonary Capillary Blood Flow ◽  
Time Period ◽  
Pulmonary Capillary ◽  
Wide Range ◽  
Pulmonary Capillary Blood ◽  
The Difference

Pulmonary capillary blood flow (Qc) in the exercising subject was calculated from the rate of disappearance of N2O during steady state breathing of an N2O-He-O2 mixture. Measurements were made after alveolar rinsing (reciprocal of N2 washout) had occurred, and up to 30 sec, a time period accompanied by minimal recirculation, since FaNN2O during this period did not rise significantly. Repeatability of the method, judged as the difference of a second estimate from a first on the same subject, was comparable to that reported for the direct Fick technique in resting subjects (31 of 33 paired observations agreed within 20%). Results over a wide range agreed with almost simultaneous measurements by a dye dilution technique (24 of 26 paired observations agreed within 20%), and when related to pulse rate and to Vo2, were comparable to those of the other workers whose subjects were studied in a similar posture. Indeed, this technique (using the indirect Fick principle under “steady state” conditions) probably attains its greatest accuracy during exercise when other methods become less easily applicable. Submitted on December 18, 1961

Skimming of microspheres in vitro: implications for measurement of intrarenal blood flow

1981 ◽  
Vol 241 (3) ◽  
pp. H342-H347 ◽  
Author(s):  
E. S. Ofjord ◽  
G. Clausen ◽  
K. Aukland
Keyword(s):  
Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Particle Inertia ◽  
Local Flow ◽  
Size Dependent ◽  
Dog Kidney ◽  
Intrarenal Blood Flow ◽  
Renal Cortical Blood Flow

Skimming could result in erroneous estimation of renal cortical blood flow distribution as measured by microspheres. Skimming of microspheres with diameters 10, 12, and 15 micrometers and red blood cells was therefore studied in a model in which an interlobular artery and its first arteriolar branch were simulated by 80- and 30-micrometers-wide slits between glass prisms. The experiments were performed with citrated blood at a hematocrit (Hct) of 40, flow velocities of 3 and 6 cm/s, and branch flow varying from 2 to 25%. At a branch flow fraction comparable to that of a deep arteriole in the dog kidney (3%), Hct in branch blood was 24% lower than that of input blood, whereas 10-, 12-, and 15-micrometers microsphere concentrations were 75, 81, and 87% lower, respectively. The size-dependent skimming was probably caused by wall exclusion in the main channel. Differences in particle inertia did not affect skimming. The results suggest that the disparate local flow values obtained by use of microspheres of different sizes in dog and rat kidneys are due to a size-dependent skimming of the microspheres.

Sign in / Sign up

Export Citation Format

Share Document