ABSTRACT
Edema, external compression, passive stretch of a muscle and muscle contraction, or any combination of the four factors increases intramuscular pressure. Intramuscular pressure can be defined by the Starling equation (Equation 1.1),
which describes the magnitude and direction of fluid shift (
Jc
) over the capillary wall by the two hydrostatic and two osmotic pressures (Figure 1.1):
Jc
=
Kf
[(
Pc
–
Pt
) –
b
(
p
–
p
)] (1.1)
where
Jc
is the net fluid flow across the capillary wall,
Kf
the capillary filtration coefficient,
Pc
the capillary blood hydrostatic pressure,
Pt
the hydrostatic pressure in the interstitial fluid,
b
the capillary membrane reflection coefficient,
p
c
the capillary blood colloid-osmotic pressure, and
p
the osmotic pressure in the interstitial fluid.
