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Effect of perfusionist technique on cerebral embolization during cardiopulmonary bypass
Rosendo A Rodriguez1, Kathryn A Williams, Andrei Babaev
1Department of Anesthesiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. Rrodriguez@Ottawaheart.ca
Insights
Perfusionist interventions during cardiopulmonary bypass, like purging the oxygenator or using bolus drug injections, increase high-intensity transient signals (HITS), indicating potential cerebral emboli. Minimizing these interventions can reduce HITS during surgery.
Area of Science:
- Cardiovascular Surgery
- Neuroanesthesia
- Perfusion Technology
Background:
- High-intensity transient signals (HITS) detected via transcranial Doppler are indicators of cerebral emboli.
- Perfusionist interventions during cardiopulmonary bypass (CPB) may contribute to HITS.
- Understanding the relationship between CPB management and HITS is crucial for patient safety.
Purpose of the Study:
- To investigate the association between high-intensity transient signals (HITS) and specific perfusionist interventions during CPB.
- To identify which CPB management strategies, including purging, drug administration, pump flow, and reservoir volume, correlate with HITS.
Main Methods:
- Transcranial Doppler monitoring was used to detect HITS in the middle cerebral artery during CPB in coronary artery bypass grafting patients.
- Perfusionist interventions, such as blood sampling, purging of the oxygenator sampling manifold, drug bolus injections, infusions, pump flows, and venous reservoir volume, were meticulously recorded.
Main Results:
- A total of 534 interventions across 90 patients were analyzed, with a median of 17 HITS per patient.
- Intervention type and individual perfusionist significantly influenced HITS counts (p <0.0001 and p =0.0012, respectively).
- Blood sampling and drug bolus injections generated more HITS than infusions. Repetitive purging (p <0.001), lower reservoir volumes (< or =800 mL, p =0.001), and higher pump flow rates (p =0.008) were associated with increased HITS.
Conclusions:
- Cerebral emboli, indicated by HITS, can be reduced by avoiding oxygenator sampling manifold purging.
- Utilizing continuous infusions over bolus injections and maintaining venous reservoir volumes above 800 mL are recommended strategies to minimize HITS during CPB.
Objective:
To determine the association between high-intensity transient signals (HITS) and perfusionist interventions, purging techniques, pump flows and venous reservoir blood volume levels during cardiopulmonary bypass.
Methods:
Transcranial Doppler was used to detect HITS in the middle cerebral artery during the period of aortic crossclamping in patients undergoing coronary artery bypass grafting. Perfusionist-related interventions were recorded and included blood sampling (including the number of times that the oxygenator sampling manifold was purged), drug bolus injections and infusions (vasopressors, crystalloid and mannitol). Pump flows and venous reservoir volume levels were also documented.
Results:
There were 534 interventions in 90 patients [median number of interventions per patient: 6 (quartiles: 4, 8)]. The median total HITS count from all interventions was 17 (5, 37). This represented 38% of the total HITS counts during aortic crossclamping. Factors contributing to differences in the HITS count included type of intervention (p <0.0001) and perfusionist (p =0.0012). Blood sampling (p<0.001) and drug bolus injections (p=0.06) had higher HITS counts per patient than infusions. Repetitive purging significantly increased HITS counts (r=0.74; p <0.001). Purging perfusionists (purging: 1-10 times) had higher HITS counts per patient [5 HITS (1, 15) than nonpurgers [0 HITS (0, 1) p <0.0001]. HITS counts were significantly correlated with reservoir volumes (r= -0.20, p=0.017) and pump flow rates (r=0.21, p =0.008). Reservoir volume levels < or =800 mL were associated with higher HITS counts per intervention [11 HITS (2, 27)] during blood sampling compared with higher volume levels [3 HITS (1, 10), p =0.001].
Conclusions:
Cerebral emboli associated with perfusionist interventions can be minimized by not purging the sampling manifold, using continuous infusions rather than bolus injections, and maintaining high blood-volume levels (>800mL) in the venous reservoir.
