Hazard [Health Devices Jan 1990;19(1):25-7]
In two investigations of intraoperative autotransfusion procedures at
different institutions, ECRI determined that excessive vacuum levels and insufficient
normal saline wash volumes during orthopedic surgery led to gross hemolysis and subsequent
renal dysfunction. In each case, the patient required hemodialysis for two to three weeks,
and one also required mechanical ventilation for three weeks.
In intraoperative autotransfusion, blood is removed from the surgical site
with a suction catheter connected to either a central vacuum system or an aspirator and
mixed with an anticoagulant (e.g., heparin or citrate solution) as it is drawn into the
reservoir of the autotransfusion unit. The anticoagulated blood is then washed with normal
(isotonic) saline in a centrifuge and reduced to a unit of packed red blood cells for
Autotransfusion units have Manual or Manual/Automatic modes for filling
the centrifuge, washing the blood, and emptying the packed cells from the centrifuge into
a collection bag. In Manual mode, an operator determines the volume of normal saline and
the length of time for the wash cycle. In Automatic mode, the unit is programmed for a
specified wash volume. Some units have an Automatic mode for different applications
(primarily cardiovascular and orthopedic surgery).
The operator's manuals of most autotransfusion devices state a maximum
recommended reservoir vacuum level of 100-150 mm Hg. (Central vacuum systems and many
aspirators can attain a maximum vacuum of more than 500 mm Hg.) In its July 1988
guidelines for salvaging intraoperative blood, the National Autologous Blood Resource
Information Center (of the American Association of Blood Banks) stated that "the
vacuum in the collection reservoir should be regulated as far as possible to be less than
100 mm Hg." That document also raises concern about suctioning shallow pools of blood
from tissue surfaces where the air-blood interface increases turbulence. Turbulence that
results from either excessive vacuum level or suctioning air mixed with blood is a major
cause of hemolysis. To further minimize hemolysis, the guidelines recommend that "a
plastic suction tip with a large orifice should be used."
Blood is more likely to be hemolyzed in the suctioning process in
orthopedic cases than in cardiovascular cases for three reasons: 1) Surgical sites tend
to be shallower, and it is more difficult to suction without "skimming" (i.e.,
sucking in air with the blood). 2) Orthopedic procedures tend to produce more surgical
debris; this debris causes partial blockage of the suction tip holes, resulting in
increased blood velocity and turbulence at these sites. 3) Blood may ooze for long
periods from capillary beds, whereas bleeders are easier to locate and ligate or
During our investigations, we found that neither device operator knew how
to properly adjust the suction regulator. One operator believed that it could be done by
listening to the sound of the airflow. In addition, if the regulator is adjusted with the
line open to air (using the regulator gauge), a much greater vacuum level will result when
flow resistance (e.g., from suctioned blood) is encountered.
To ensure that the vacuum level does not exceed the set level, clamp the
catheter line while the regulator is adjusted using the gauge. Few clinical personnel appear to be aware of this
technique, which should be performed whenever a low or precise vacuum level is
required (e.g., for tracheal suctioning). The correct procedure for adjusting
suction should be fully discussed in suction regulator and autotransfusion unit
operator's manuals and emphasized during operator training by autotransfusion
We therefore recommend use of a suction regulator with a factory-set maximum vacuum level of
150-200 mm Hg for autotransfusion. For blood-processing units used with central vacuum systems,
hospitals may wish to consider mounting the regulator on the unit. An alternate vacuum
source (greater than or equal to 300 mm Hg) should be
immediately available for the occasional surgical conditions that require high-flow
suction (e.g., ruptured aneurysm, major trauma). (In the event of massive hemorrhage,
salvaging blood is secondary to clearing the surgical site and achieving hemostasis.)
At one hospital, a suction regulator gauge was out of calibration by 100
mm Hg, while another regulator was defective and could not be adjusted below 400 mm Hg.
Suction regulators are frequently damaged when overflow protection is not used or is
defective. In addition, because they are small, portable devices, regulators may receive a
great deal of physical abuse, particularly in an OR. We know of very few clinical
engineering departments that routinely inspect suction regulators. We believe that these
devices should be included in an equipment control program and inspected at least once a
year. Accordingly, we have developed a procedure for the Health Devices Inspection and
Preventive Maintenance System. It may also be advisable for autotransfusion unit
operators to verify suction regulator accuracy and function more frequently (e.g.,
Blood processed for autotransfusion should be
washed until the waste effluent is clear. Although 1 L of normal saline is
generally sufficient for washing each unit of blood collected during
cardiovascular surgery, a greater wash volume (greater than or equal to1
.5 L) is almost always required to clean blood from orthopedic
surgical cases. (One source suggests a wash volume equal to seven times the centrifuge
bowl volume.)(1) Blood from orthopedic cases usually contains more fat, activated clotting
factors, free hemoglobin (released from lysed red cells), and stroma (the cell membranes
of lysed red cells). If these components are not removed before reinfusion, especially in
cases where multiple units are processed, they may cause renal dysfunction and, possibly,
respiratory distress syndrome in adults. A greater wash volume may also be necessary to
remove the larger amounts of irrigation solution and anticoagulant typically used in
orthopedic cases. Autotransfusion units with an Automatic mode permitting only a 1 L
wash must be used in the Manual mode when a greater wash volume is needed.
- Clamp the catheter line when adjusting suction
- Attempt blood suctioning for autotransfusion with
both blood-processing and whole-blood-recovery units at a vacuum level of
100 mm Hg. Use a suction regulator with a factory-set maximum vacuum level
of 150-200 mm Hg. An alternate vacuum source with a maximum vacuum level
greater than or equal to 300 mm Hg should be available for situations
requiring high-flow suction.
- Minimize suctioning air with blood.
- Use a plastic suction tip with several large holes.
- Add suction regulators to hospital equipment
control programs. They should be inspected annually by clinical engineering,
respiratory therapy, or other qualified staff.
- Users should periodically verify the accuracy and
function of suction regulators used for autotransfusion.
- When using blood-processing autotransfusion units,
wash blood until the saline entering the waste bag is clear. Blood from
orthopedic surgical cases will generally require a minimum wash volume of
- Blood-processing autotransfusion units with Automatic mode fixed-volume
wash cycles of only 1 L should be prominently labeled:
Do not use Automatic mode for orthopedic surgery. In Manual mode, wash
with a minimum volume of 1.5 L or until clear.
* Use a vacuum gauge or electronic pressure
meter to check maximum suction. Then, disconnect the gauge or meter, turn the
regulator off, reconnect the gauge or meter, and verify the accuracy at a
setting of 100 mm Hg.
- Flynn JC, Metzger CR, Csencsitz TA.
Intraoperative autotransfusion (IAT) in spinal surgery. Spine
- Autotransfusion Units, Blood Processing [17-537]
- Autotransfusion Units, Whole Blood Recovery
- Regulators, Suction [13-325]
Device factor: Improper maintenance, testing,
repair, or lack or failure of incoming inspection
User errors: Failure to read label; Incorrect
External factor: Medical gas and vacuum
Mechanism of Injury or