Transcapillary refill in hemorrhage and shock
W. R. Drucker, C. D. Chadwick and D. S. Gann
Moderate or major hemorrhage leads to diminished cardiac output and to
increased total peripheral resistance. These cannot be corrected fully
until blood volume is restored, which, in the absence of therapy, requires
the movement of fluid and of protein from the interstitium into the
capillaries. This movement appears mediated entirely by changes in the
Starling forces, dominated in the first phase by a fall in capillary
hydrostatic pressure, which promotes a rapid shift of protein-free fluid
from the interstitium into the capillaries. The second phase, temporally
overlapping the initial phase, involves the return of protein to support
plasma oncotic pressure. Interstitial albumin probably constitutes the
source of the immediate restoration of plasma protein. The driving force
for return of the protein depends on interstitial volume and pressure,
which in turn appear to depend on movement of fluid from cells to the
interstitium, mediated by an increase in solute bathing the cells,
especially glucose. It is suggested that this solute is delivered to
peripheral cells from the splanchnic bed, where it appears to be formed
under the action of hormones whose secretion is stimulated by hemorrhage
and injury.
