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Cardiotomy suction: a major source of brain lipid emboli during cardiopulmonary bypass
R F Brooker1, W R Brown, D M Moody
1Department of Anesthesia, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1088, USA.
Insights
Cardiopulmonary bypass (CPB) during heart surgery can cause brain injury. Using cardiotomy suction during CPB significantly increases lipid microemboli in brain capillaries, leading to more dilatations.
Area of Science:
- Cardiovascular Surgery
- Neurology
- Pathology
Background:
- Brain injury is a serious complication for patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).
- Autopsy studies reveal lipid deposits in the microvasculature of brains from patients after cardiac operations with CPB.
- These dilatations may stem from inflammation or emboli associated with CPB.
Purpose of the Study:
- To investigate the cause of microvascular dilatations observed in the brain after cardiac surgery.
- To determine if CPB or specific aspects of the procedure are associated with these changes.
Main Methods:
- A canine model was used to study four groups undergoing different CPB protocols for 60 minutes.
- Groups included right-heart CPB, lower-extremity CPB, hypothermic CPB, and hypothermic CPB with cardiotomy suction.
- Brain specimens were analyzed histochemically to quantify microvascular dilatations.
Main Results:
- All dogs completed the study protocol.
- The group undergoing hypothermic CPB with cardiotomy suction exhibited a significantly higher density of dilatations (46.5 +/- 14.5 per cm²) compared to other groups.
- Dilatation density in the cardiotomy suction group was significantly greater than in the hypothermic CPB group (p = 0.04).
Conclusions:
- Reinfusion of blood from the surgical field via cardiotomy suction during CPB leads to a higher density of microvascular dilatations.
- This suggests that lipid microembolization from cardiotomy suction is a primary contributor to these brain microvascular changes.
Background:
Brain injury remains a significant problem in patients undergoing cardiac surgery assisted by cardiopulmonary bypass (CPB). Autopsy brain specimens of patients after cardiac operations with CPB reveal numerous acellular lipid deposits (10 to 70 microm) in the microvasculature. We hypothesize that these small capillary and arterial dilatations result from a diffuse inflammatory response to CPB or from emboli delivered by the bypass circuit. This study was undertaken to determine which aspect of CPB is most clearly associated with these dilatations.
Methods:
Thirteen dogs were studied in four groups: group I (n = 3), right-heart CPB; group II (n = 2), lower-extremity CPB; group III (n = 3), hypothermic CPB; and group IV (n = 5), hypothermic CPB with cardiotomy suction. All dogs in all groups were maintained on CPB for 60 minutes and then euthanized. Brain specimens were harvested, fixed in ethanol, embedded in celloidin, and stained with the alkaline phosphate histochemical technique so that dilatations could be counted.
Results:
All dogs completed the protocol. The mean density of dilatations per square centimeter for each group was as follows: group I, 1.77 +/- 0.77; group II, 4.17 +/- 1.65; group III, 4.54 +/- 1.69; and group IV, 46.5 +/- 14.5. In group IV (cardiotomy suction), dilatation density was significantly higher than in group III (hypothermic cardiopulmonary bypass) (p = 0.04) and all other groups (p = 0.04).
Conclusions:
Blood aspirated from the surgical field and subsequently reinfused into dogs undergoing CPB produces a greater density of small capillary and arterial dilatations than CPB without cardiotomy suction, presumably because of lipid microembolization.
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