Red blood cells may become hemolyzed by mechanical forces during blood infusion. This risk can be minimized by careful attention to the infusion system. In general a combination of several factors is required to produce mechanical hemolysis.

Factors implicated in mechanical hemolysis:

(1) use of an infusion pump, especially when used improperly

(2) use of a very small diameter needle

(3) attempting to infuse quickly using high pressures

(4) fibrin or other barrier in the blood vessel

(5) blood product with high viscosity


Peristaltic and diaphragm-type pumps have been asssociated with increased hemolysis of packed red blood cells. A pump should be tested for its effect on red blood cells before it is used to infuse blood.


Blood can be infused safely through a small caliber needle provided it is done slowly and with low pressure. The flow rate should be < 50 mL per hour.


Other factors implicated in mechanical hemolysis:

(1) increased length of tubing

(2) decreased diameter of tubing

(3) use of a filter

(4) decreased viability of red cells (older blood product, other)

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