Hematic Antegrade Repriming: A Reproducible Method to Decrease the Cardiopulmonary Bypass Insult

Abstract

The current practice of cardiopulmonary bypass (CPB) requires a preoperative priming of the circuit that is frequently performed with crystalloid solutions. Crystalloid priming avoids massive embolism but is unable to eliminate all microbubbles contained in the circuit. In addition, it causes a sudden hemodilution which is correlated with transfusion requirements and an increased risk of cognitive impairment. Several repriming techniques using autologous blood, collectively termed retrograde autologous priming (RAP), have been demonstrated to reduce the hemodilutional impact of CPB. However, the current heterogeneity in the practice of RAP limits its evidence and benefits. Here, we describe hematic antegrade repriming as an easy and reliable method that could be applied with any circuit in the market to decrease transfusion requirements, emboli, and inflammatory responses, reducing costs and the impact of CPB on postoperative recovery.

Keywords: MiECC; cardiopulmonary bypass; hematic priming; hemodilution; microemboli.

Figure 1.

The HAR class IV MiECC design. Lines: 1: 3/8 × 35 cm. 2: 3/8 × 40 cm. 3: 3/8 × 25 cm. 4: 3/8 × 55 cm. 5: 3/8 × 135. 6: 3/8 × 105 cm. 7: 3/8 × 40 cm. 8: 1/8 (double-male luer-lock connector) × 70 cm (clamp included). Dynamic priming: 1,000 mL. Final priming after HAR: 300 mL. Preprinted as: (10).

Figure 2.

HAR, the six-step procedure. Step 1: Venous line recovery: starting in Pos.1, set VAVD to −30 mmHg. Remove clamp A, collecting 300 ± 50 mL of crystalloid volume in the reservoir. Replace clamp A afterward. Step 2: Arterial line recovery: starting in Pos.2, remove clamp B after arterial line connection to the aortic cannula. Then, remove clamp D, re-priming the arterial line retrogradely until the recirculation line is primed with blood, and clamp it back afterward, avoiding the mixture of blood and crystalloid in the reservoir. The mean arterial pressure should be maintained above 60 mmHg (MAP > 60 mmHg). In this manoeuvre, 50–80 mL of additional crystalloid are collected. Step 3*: Priming withdrawal: when using a centrifugal pump (CP), increase the flow up to 2,000 rpm, then open clamp E. If using a roller pump (RP), first open clamp E, then set the flow rate to 250–500 mL/min. This should displace the crystalloid volume contained in the reservoir toward the collector bag until there is no crystalloid volume in the reservoir (zero level). Step 4*: Arterial “sequestration”: place clamp F on the base of the reservoir to prevent blood from mixing with the crystalloid solution during “sequestration.” Then, open clamp D gently (maintain a backflow between 100 and 300 mL/min, MAP > 60 mmHg) until 300–400 mL of blood are obtained in the reservoir. Close clamp D afterward. Step 5*: Antegrade re-priming: if using a CP, remove clamp F and increase the flow to 2,000 rpm, then open clamp E to re-prime the circuit. If using a RP, first open clamps F and E to avoid system over-pressurization, then initiate a 250–500 mL/min flow. Antegrade re-priming should be performed until the blood reaches the collector bag to maximize benefits. Once HAR is complete, ensure that clamp D and clamp E are closed. The three-way stopcock H must also be closed, blocking flow to the collector bag. Step 6: CPB initiation: set VAVD to −30 mmHg and remove clamp A. If using a CP, raise the pump speed to 1,500 rpm, then remove clamp C and continue increasing CP speed to the target flow. If using a RP, remove clamp C and initiate perfusion progressively up to the target flow. *Steps 3, 4, and 5 are performed during the venous cannulation, and the suckers can be activated since the step 4. Preprinted as: (11).