Abdominal, Thoracic, and Pericadial Effusions Flashcards
A small amount of free peritoneal fluid is normal in what species?
fluid can be collected from the peritoneal cavities in clinically healthy horses, cattle, and camelids and the judgment as to whether there is an abnormal or excessive amount of fluid within the cavity is best made clinically.
The main mechanisms by which transudation can occur: (3)
This is due to altered hydrodynamic forces within the vessels serving or draining capillary beds or the interstitium (lymphatics).
- Increased plasma hydrodynamic pressure, this is usually from increased venous pressure (e.g. venous hypertension) but can be from increased blood delivery to capillary beds (arterial hypertension or dilation), although the latter is less common.
- Decreased lymphatic drainage (increases tissue hydrostatic pressure).
- Decreased plasma oncotic pressure (hypoalbuminemia)
The main mechanisms by which an exudate can occur:
This is due to increased capillary permeability and is mediated by vasoactive mediators, usually as a consequence of inflammation.
This may or may not be accompanied by chemotaxis of leukocytes in response to inflammatory cytokines.
Body cavity fluids should be collected into an
EDTA-anticoagulant (purple top) tube. This tube is preferred because cell features are better maintained and bacterial proliferation is inhibited.
Concurrent collection of fluid into a non-anticoagulant (red top) tube is always useful with bloody fluids (to observe clotting) or in case additional testing is desired, e.g. creatinine, total bilirubin or bacteriology.
At the minimum, what should be done with a collected body cavity fluid?
At the minimum, a direct smear (from unconcentrated fluid) should be made from the fluid, however if the sample is poorly cellular, there will be insufficient cells to examine.
With a poorly cellular sample, it is worthwhile making smears of concentrated fluids (after centrifugation), using only a portion (and not all) of the fluid.
Direct smears should suffice for a flocculent or non-opaque fluid.
Fluid analysis begins during
collection of the sample, with observation for blood contamination, ease of collection, and how much fluid is present in the animal.
if the fluid is white and opaque it will most likely be
chylous in nature
if the fluid is from a cat and is yellow and highly viscous (perhaps with a fibrin clot], what should be considered
infection with feline infectious peritonitis virus should be considered
body cavity Fluid analysis should include (4)
gross evaluation
cell counts (nucleated and RBCs)
protein content
cytologic eval.
how to do a cell count for a body cavity effusion?
Nucleated and RBC counts are performed by automated methods (lasercyte/procyte) but can be done using manual methods (hemacytometer).
Note, nucleated cells include leukocytes and mesothelial or cancer cells. It also can include non-nucleated cells, such as bacteria and intestinal contents (so never rely on counts – always look at a smear).
how to measure protein content of a body cavity effusion?
This is estimated on a supernatant of the fluid (if cloudy or turbid) using a refractometer. (often is the left side scale, NOT the s.g. scale on the right)
A more accurate protein can be obtained on automated chemistry analyzer, however this is more expensive and not typically done.
how to: cytologic eval. of a body cavity effusion?
microscopic examination of a Wright’s or Diff-Quik-stained smear.
Fluids with very high nucleated cell counts (>20-30,000/uL) can be prepared without concentration of the cells (direct smear), while concentration techniques such as sediment smears can be used for lower cell count effusions.
The following cells are normally present in cavity fluids: (5)
macrophages: are present in all types of effusions.
neutrophils: These are non-degenerate.
lymphocytes: These are mostly small cells and are present in low numbers.
eosinophils and mast cells: Low numbers may be present.
mesothial cells: These are the lining cells of serosal cavities. Spontaneously exfoliated mesothelial cells are round cells with round, central nuclei.
describe transudates with low protein content
usually colorless to light yellow, and transparent
TP <2.5
cell count x10^3/ul <1.5 (pure transudate) but also <5.0
Pleural fluid: Increased venous or lymphatic hypertension (non-exfoliating neoplasia, lung lobe torsion, etc).
Peritoneal fluid: Portal hypertension (liver disease), severe hypoalbuminemia (< 1.5 g/dL, an uncommon cause of effusion by itself, often combined with portal hypertension), non-exfoliating neoplasia.
describe transudates with high protein content
TP >2.5
cell count x10^3/ul <5.0
Fluid is usually light to moderate yellow, may be blood-tinged and transparent to slightly cloudy (from WBC and RBC).
minimum values for total protein content &
total nucleated cell count for transudates
< 2.5 g/dl protein
< 1500 nucleated cells/microliter
minimum values for total protein content &
total nucleated cell count for modified transudates
2.5- 7.5 g/dl protein
1000- 7000 nucleated cells/microliter
minimum values for total protein content &
total nucleated cell count for exudates
> 3.0 g/dl protein
7000 nucleated cells/microliter
