1. Keep on movin’ don’t stop
Starling’s Equation
Keep on movin’ don’t stop
Group Members: Sahra Adan, Claire Anderson, Aminah Coleman, Wai Chum, Joseph Early, Mindy Gunn, Kyle McIntyre, Monicah Ngugi, Kathryn Sjolund, Lise Thorsvig, Lindsey Tripp, & Vincent Witwer

2. Filtration through membranes
Affected by 3 factors:
Hydrostatic pressure (HP) gradient (pushing)
Oncotic pressure gradient (OP) (pulling)
Permeability of membrane (through what?)
Where does water go? ….
In the direction where the force is GREATER!!!!!
Net: HP (Side A) – HP (Side b)
Net: OP (side A) – OP (side B)
Hydrostatic pressure: force generated by water, due to the force of gravity
Oncotic pressure: force generated by solutes (major solute: albumin)
Determine the net force by calculating hydrostatic and osmotic pressure at two different sides of a membrane,
Hydrostatic pressure (side A) - Hydrostatic pressure (side B)
Oncotic pressure (side A) - oncotic pressure (side B)
B A

3. Membrane Characteristics: Lp, s (little) and s (big)
Lp and S (big) affect HYDROSTATIC pressure:
Lp- porosity of the membrane
S (big) - membrane surface area
S (little) affects OSMOTIC pressure:
S (little)- permeability of a membrane to a solute
Ranges from 0 (completely permeable) to 1 (completely impermeable)
Solute diffusion      as permeability
The membrane factors affecting hydrostatic pressure are rarely clinically relevant.
Permeability of a membrane to a solute is clinically relevant in disorders which disrupt membrane integrity (such as sepsis).

4. The Math of Starling’s Equation Means
Movement of water between interstitial space and capillaries
Increased hydrostatic pressure = positive net filtration
inside the capillary
Increased oncotic pressure = negative net filtration
Interstitial space
Taking into account all factors, the Starling’s Law can be rewritten mathematically as:
net filtration pressure = [Lp x S (BIG)] )(capillary hp – interstitial hp) – [s(little) x (capillary op – interstitial op)]

5. Importance of Starling’s Law
This affects the flow of fluid and filtrates into and out of your capillaries...
At the ARTERIAL end of the capillary:
Net filtration pressure is POSITIVE, causing water, oxygen and nutrients to be pushed OUT of the capillary and into the interstitial fluid.
At the VENOUS end of the capillary:
Net filtration pressure is NEGATIVE, allowing the veins to pick up excess water, carbon dioxide, and other wastes from the interstitial fluid.  

6. Clinical Correlations: Pleural Fluid Analysis
High [ protein ] Low [protein ] due to damaged capillaries due to hydrostatic pressure -or- oncotic pressure “Exudate” “transudate” Inflammation, Infection, Trauma, chf, cirrhosis, severe malnutrition, Malignancy, ARDS nephrotic syndrome
transudate and exudate are classifications of pleural fluid (pleural effusion)
Determining the amount of protein and other factors contained in the fluid can help determine if the fluid collection is due to a change in hydrostatic pressure, osmotic pressure or capillary permeability (changes in capillary permeability are typically a result of damage).
Although the fluid from peripheral edema cannot be analyzed, thinking about the differential diagnosis in terms of which aspect of Starling’s law has been altered is useful. A “transudative peripheral edema” is associated with CHF and cirrhosis while an “exudative peripheral edema” is associated with infection (local or systemic), trauma and malignancy.
Diagnostic criteria: One the following is required for the pleural fluid to be considered an exudate. LDH = lactate dehydrogenase.
pleural fluid protein more
than 50% of serum protein
• pleural fluid LDH more than
60% of serum LDH
66% of the upper limit of
normal for serum LDH

7. Clinical Correlations
Fluid collections always result from a change in one component of Starling’s law ascites, peripheral edema, pulmonary edema, pleural effusion
Changes in net osmotic pressure do not become clinically significant until the plasma albumin concentration is less than 2 g/dL (normal 3.5 to 5.5 g/dL).
Decreased plasma protein concentration can be due to decreased production (e.g., chronic liver disease, severe malnutrition) or increased loss (e.g., nephrotic
syndrome, protein losing enteropathies)

8. Clinical Correlations: Albumin Gradient albumin gradient = plasma albumin – ascitic albumin
High Gradient >1.1 g/dL Low Gradient < 1.1 g/dl
Cirrhosis malignancy
Hepatitis tb
CHF pancreatic disease
Portal vein thrombosis nephrotic syndrome
myxedema
Ascites

9. Summary

10. In words
Starling’s Law explains the maintenance of fluid balance between the vasculature and the interstitial space.
Fluid balance is determined by hydrostatic and oncotic pressure balance
In a healthy person: high hydrostatic pressure forces water to filter out of capillaries at the arterial end
At the venous end, hydrostatic pressure is decreased, thus oncotic pressure - mainly the pull of the plasma proteins – returns water into the vasculature
In a disease state: hydrostatic or oncotic pressure are altered and water flows from the vasculature to the interstitial space
Membrane permeability also impacts the flow of water.