Authors

S Disney¹;  ¹ University Hospitals Plymouth NHS Trust, UK

Objective

An important part of the perfusionist's role is to mitigate the risk of emboli during cardiopulmonary bypass. However, there are still incidents of air being pumped to the patient via suckers and vents. One mechanism that can help to reduce these incidents is the implementation of one-way valves in the sucker and vent lines. It is currently unknown whether or not more microemboli is generated as a consequence of having these one-way valves in. Therefore, the aim of the study is to determine whether or not more air is delivered to the patient with one-way valves in the suckers and vents compared to not having one, as well as discovering under what conditions this may occur.

Method

There were 2 experimental arms; valved and non valved. Each arm was tested under 4 conditions; fully open (only blood running through), having the line fully occluded, blood plus a bolus of air, partial occlusion on the sucker line. Each of these aimed to replicate scenarios seen in clinic. Each test condition was completed 3 times for 2 minutes with pre and post oxygenator bubble number, size and volume counted. The average of the 3 tests was calculated and then compared between groups.

Results

The results showed that in the fully open and fully occluded groups there was very little difference between air number and volume between the valved and non valved suckers. However, in the bolus of air and partially occluded groups post oxygenator bubble count and volume were significantly raised in the valved arm compared to the non valved. In the air bolus valved group post oxygenator total counts and volume were 1138 and 28.03nl respectively compared to 144 and 3.5nl in the non valved arm. Similarly in the partially clamped groups valved total post oxygenator bubble count was 1490 and total volume 35.9nl compared to 118 and 2.3nl in the non valved arm.

Conclusion

In conclusion the study shows that during periods of mixed air and blood and partial occlusions on the line the use of a one-way valve in the suckers and vents may produce and deliver more microemboli to the patient. However, this may vary depending on the stressors placed on the vents and suckers during each case and may be different between centres, surgeons and different operations. The clinical significance of this would be extremely difficult to prove and it may be worth further exploring whether different brands of one way valves differ in their production of microemboli.