Vacuum assisted venous drainage (VAVD)

Poor venous drainage is a common problem in cardiac surgery, causing trouble for the surgeon and adverse effects to the patient. Smaller incisions for minimally invasive cardiac surgery require smaller venous catheters. In this study the function, safety and possible benefits of a system for vacuum assisted venous drainage has been tested experimentally and applied clinically. A vacuum regulator ('The Hamlet box') and safety procedures were developed. The system was characterized in vitro in regard to the relationship between vacuum, catheter size, and blood temperature and flow. The clinical study included 54 adult patients, coronary artery bypass graft surgery and valve operations. Venous cannulation was bi-caval with two 24 Fr catheters. All the perfusions were essentially event free, and the system was easy to manage and regulate. Venous drainage was totally adequate, irrespective of the position of the heart, and less fluid was added during the perfusions (a median of 250 ml/patient compared to a median of 1000 ml/patient in the control group). There has been no evidence of increased haemolysis or other adverse effects. All patients were hospital survivors and had uneventful postoperative courses. Vacuum assisted venous drainage is now used routinely, and further studies are under way to develop the system and clarify the physiological effects.