Final answer:
Bleeding stops when the dressing's pressure exceeds the blood hydrostatic pressure, which in this scenario is more than 55 mm Hg.
Step-by-step explanation:
Bleeding will almost always stop when the pressure of the dressing exceeds capillary hydrostatic pressure (CHP). Given that the blood hydrostatic pressure is 55 mm Hg and colloid osmotic pressure (BCOP) is considered to be around 30 mm Hg, the dressing needs to exert a pressure that is more than the blood hydrostatic pressure to be effective in halting bleeding. From the information provided, we can gather that at the arterial end of a capillary bed, CHP is approximately 35 mm Hg, which decreases towards the venous end to about 18 mm Hg. Meanwhile, BCOP remains fairly constant throughout the capillary length. Therefore, to stop the bleeding, the pressure applied must be greater than 55 mm Hg, which is the highest pressure noted for blood hydrostatic pressure within the context given.