Review Note
Last Update: 03/30/2025 10:11 PM
Current Deck: ACG Part 2::Plastic Surgery and Burns
New Card (Unpublished)Currently Published Content
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Front
Commit #312095
SS_PB 1.1 Describe the physiological principles relevant to optimising blood flow to tissue flaps, including:
- Physics of blood flow
- Physics of blood flow
Back
Commit #312095Blood flow is typically laminar and follows the Hagen-Poiseuille equation:
Flow = (ΔP × πr⁴) / (8nl)
Flow = (ΔP × πr⁴) / (8nl)
Flow is influenced by:
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Perfusion pressure, determined by Starling’s forces:
Net Fluid Flux = k [(Pcap - PISF) – σ (πcap - πISF)]-
The balance between capillary hydrostatic/interstitial hydrostatic pressures and capillary/interstitial oncotic pressures regulates fluid movement:
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Fluid enters tissues at the arteriolar end.
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Fluid returns to capillaries at the venous end.
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Calibre of the vessel – The primary determinant of blood flow, explaining why arterioles are key in regulating regional blood flow.
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Small changes in radius impact flow significantly (proportional to r⁴).
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Blood viscosity – Resistance to flow increases with viscosity.
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Optimal rheology occurs at a hematocrit of ~30%.
