INTRAOPERATIVE BLOOD COLLECTION
The term intraoperative blood collection or recovery describes
the technique of collecting and reinfusing blood lost by a patient during surgery.
The oxygen-transport properties of recovered RBCs are equivalent to those of
stored allogeneic RBCs. The survival of recovered RBCs appears to be at least comparable
to that of transfused allogeneic RBCs.[73]
Intraoperative
collection is contraindicated when certain procoagulant materials (e.g., topical
collagen), are applied to the surgical field, as systemic activation of coagulation
may result. Microaggregate filters (40 µ) are most often used, as recovered
blood may contain tissue debris, small blood clots, or bone fragments.
Cell washing devices can provide the equivalent of 12 units of
banked blood per hour to a massively bleeding patient.[73]
Data regarding adverse events of reinfusion of recovered blood have been published.
[74]
Air embolus is a potentially serious problem.
Three fatalities from air embolus were reported over a 5-year interval to the New
York State Department of Public Health, for an overall fatality risk of 1 in 30,000.
[48]
Hemolysis of recovered blood can occur during
suctioning from the surface instead of from deep pools of shed blood. For this reason,
manufacturers' guidelines recommend a maximum vacuum setting of no more than 150
torr: one study found that vacuum settings as high as 300 torr could be used, when
necessary, without causing excessive hemolysis.[75]
Patients exhibit a level of plasma-free hemoglobin that is usually higher than after
allogeneic transfusion. The clinical importance of free hemoglobin in the concentrations
usually seen has not been established, although excessive free hemoglobin may indicate
inadequate washing. Positive bacterial cultures from recovered blood are sometimes
observed; however, clinical infection is rare.[76]
Most programs use machines that collect shed blood, wash it, and concentrate the
RBCs. This process typically results in 225-mL units of saline-suspended RBCs with
a hematocrit of 50% to 60%.
Clinical Studies
As with PAD and ANH, collection and recovery of intraoperative
autologous blood should undergo scrutiny with regard to both safety and efficacy.
A controlled study in cardiothoracic surgery demonstrated a lack of efficacy when
transfusion requirements and clinical outcomes were followed.[76]
A second study found that only a minority of patients undergoing major orthopedic
and cardiac surgery achieved cost equivalence with intraoperative blood recovery
using semi-automated instruments compared to banked blood.[77]
While the collection of a minimum of one blood unit equivalent is possible for less
expensive (with unwashed blood) methods, it is generally agreed that at least two
blood unit equivalents need to be recovered using a cell-recovery instrument (with
washed blood) in order to achieve cost-effectiveness.[80]
The value of intraoperative blood collection has been best defined for vascular
surgeries with large blood losses, such as aortic aneurysm repair and liver transplantation.
[81]
However, a prospective, randomized trial[80]
of intraoperative recovery and reinfusion in patients undergoing aortic aneurysm
repair showed no benefit in a reduction of allogeneic blood exposure. The value
of this technology may be in cost savings and blood inventory considerations in patients
with substantial blood losses.
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