Routine use of self-expanding venous cannulas for cardiopulmonary bypass: benefits and pitfalls in 100 consecutive cases

Objective: Assess the performance of self-expanding venous cannulas for routine use in open-heart surgery. Methods: Prospective study in 100 unselected consecutive patients undergoing open-heart surgery with either remote or central smart venous cannulation. Results: The study focuses on the 76 consecutive adult patients (mean age 59.2±17.3 years; 60 males, 16 females) undergoing surgical procedures with total cardiopulmonary bypass for either valve procedures (42/76 patients=55.3%), ascending aorta and arch repair (20/76 patients=26.3%), coronary artery revascularization (13/76 patients=17.1%) or other procedures (11/76 patients=14.5%) with 14/76 patients (18.4%) undergoing redo surgery and 6/76 patients (7.9%) undergoing small access surgery. The mean pump flow achieved by gravity drainage alone accounted for 5.0±0.6l/min (=114% of target) in the entire study population (n=76) as compared to the calculated, theoretical pump flow of 4.4±0.5l/min (p<0.0001). For the femoral cannulation sub-group (n=35) pump flow achieved by gravity drainage alone accounted for 4.9±0.6l/min (=114% of target) as compared to the calculated theoretical pump flow of 4.3±0.4l/min (p<0.0001). The corresponding numbers for trans-subclavian cannulation (n=7) are 5.2±0.5l/min (111%) for the pump flow achieved by gravity drainage as compared to the theoretical target flow of 4.7±0.4l/min. For the central cannulation sub-group (n=34) mean flow achieved by gravity drainage with a self-expanding venous cannula accounted for 5.1±0.7l/min (=116% of target) as compared to the calculated theoretical flow of 4.4±0.6l/min (p<0.0001). Conclusion: Full or more than target flow was achieved in 97% of the patients studied undergoing CPB with self-expanding venous cannulas and gravity drainage. Remote venous cannulation with self-expanding cannulas provides similar flows as central cannulation. Augmentation of venous return is no longer necessar

Superior flow for bridge to life with self-expanding venous cannulas

Background: Recently, a compact cardiopulmonary support (CPS) system designed for quick set-up for example, during emergency cannulation, has been introduced. Traditional rectilinear percutaneous cannulas are standard for remote vascular access with the original design. The present study was designed to assess the potential of performance increase by the introduction of next-generation, self-expanding venous cannulas, which can take advantage of the luminal width of the venous vasculature despite a relatively small access orifice. Methods: Veno-arterial bypass was established in three bovine experiments (69 ± 10 kg). The Lifebridge® (Lifebridge GmbH, Munich, Germany) system was connected to the right atrium in a trans-jugular fashion with various venous cannulas; and the oxygenated blood was returned through the carotid artery with a 17 F percutaneous cannula. Two different venous cannulas were studied, and the correlation between the centrifugal pump speed (1500-3900 RPM), flow and the required negative pressure on the venous side was established: (A) Biomedicus 19 F (Medtronic, Tolochenaz, Switzerland); (B) Smart canula 18 F/36 F (Smartcanula LLC, Lausanne, Switzerland). Results: At 1500 RPM, the blood flow was 0.44 ± 0.26 l min−1 for the 19 F rectilinear cannula versus 0.73 ± 0.34 l min−1 for the 18/36 F self-expanding cannula. At 2500 RPM the blood flow was 1.63 ± 0.62 l min−1 for the 19 F rectilinear cannula versus 2.13 ± 0.34 l min−1 for the 18/36 F self-expanding cannula. At 3500 RPM, the blood flow was 2.78 ± 0.47 l min−1 for the 19 F rectilinear cannula versus 3.64 ± 0.39 l min−1 for the 18/36 F self-expanding cannula (p ≪ 0.01 for 18/36 F vs 19 F). At 1500 RPM, the venous line pressure was 18 ± 8 mmHg for the 19 F rectilinear cannula versus 19 ± 5 mmHg for the 18/36 F self-expanding cannula. At 2500 RPM the venous line pressure accounted for −22 ± 32 mmHg for the 19 F rectilinear cannula versus 2 ± 5 mmHg for the 18/36 F self-expanding cannula. At 3500 RPM, the venous line pressure was −112 ± 42 mmHg for the rectilinear cannula versus 28 ± 7 mmHg for the 18/36 F self-expanding cannula (p ≪ 0.01 for 18 F/36 F vs 19 F). Conclusions: The negative pressure required to achieve adequate venous drainage with the self-expanding venous cannula accounts for approximately 31% of the pressure necessary with the 19 F rectilinear cannula. In addition, a pump flow of more than 4 l min−1 can be achieved with the self-expanding design and a well-accepted negative inlet pressure for minimal blood trauma of less than 50 mmH