Gravity Venous Drainage and the 3/8-Inch Venous Line: What Would Poiseuille Do?

The 1/2″ venous line has long been the drainage tubing diameter of choice for adult patients undergoing cardiac surgery. However, several programs use a smaller diameter venous line when used in conjunction with kinetic-assisted venous drainage or vacuum-assisted venous drainage. In 2014, our perfusion team made an institution-wide effort to miniaturize the cardiopulmonary bypass (CPB) circuit for children. One of our changes was the transition to a 3/8″ diameter venous line for drainage, even in our larger patients (up to 80 kg). We reviewed the current literature on this topic and delineated the various parameters required to be able to use the 3/8″ venous line with gravity drainage with the aim of using it on patients up to 115 kg with the appropriate venous reservoir. We have successfully used the 3/8″ venous line in more than 40 of our larger patients (35-90 kg) without the need for assisted venous drainage. We were able to reduce CPB prime from 625 ± 118 to 425 ± 52 mL before retrograde autologous priming (RAP)/venous autologous priming (VAP). The prime was further reduced to 325 ± 66 mL after RAP/VAP. Homologous blood utilization was reduced from 217 ± 311 mL to 27 ± 77 mL. Both results were statistically significant. We hypothesize that taking into account two of the parameters of Poiseuille's law, namely length and diameter, it is possible to safely drain large children and mid-size adults via gravity venous drainage and the 3/8″ venous line. This technique allows reducing prime volume, simplifies CPB circuits with increased safety and potentially reduces the need for homologous blood transfusion.

The Novel Use of a Low Prime Modified Ultrafiltration Apparatus in a 13-kg Jehovah's Witness Patient: A Case Report.

Modified ultrafiltration (MUF) is used in neonates and infants to reduce volume overload and increase oxygen-carrying capacity post cardiopulmonary bypass (CPB). In addition, it decreases edema, attenuates complementation activation and immunogenic response to CPB. Hemodilution in the pediatric patient has always been a challenge, countered in part by miniaturization of CPB circuits. We describe a case in which we maintained an acceptable hematocrit level greater than 24%, considered the nadir below which the adverse effects of hemodilution can become evident. We performed this by the novel use of an intravenous warming device (enFlow, Vyaire Medical, Mettawa, IL) to reduce the prime volume of our MUF circuit by more than 50%. We present the case and discuss the advantages and disadvantages of using a low-prime MUF circuit. We were able to conduct "bloodless" CPB, with the use of acute normovolemic hemodilution, miniaturization of the CPB and MUF circuits.

Bloodless Heart Surgery for an 11-kg Infant of the Jehovah's Witness Faith Undergoing Second Repair for Complete Atrioventricular Canal.

Bloodless pediatric cardiac surgery is the intent of most surgical centers especially in the Jehovah's Witness population where it is a desire not to administer blood products because of religious belief. It is a tremendous feat, considering that most pediatric cardiovascular prime volumes are more than 20% of the patient's estimated blood volume (EBV). We report on our bloodless strategy for a 2-year old Jehovah's Witness with trisomy 21 and complete atrioventricular canal repair, who underwent atrial septal defect and ventricular septal defect patch closure, pulmonary artery debanding, and pulmonary arterioplasty. We modified our circuit to reduce our prime volume to approximately 10% of the EBV and removed 200 mL of the patient's blood before surgery as acute normovolemic hemodilution. We did not alter our institutional standards for transfusion of blood and blood products. The post cardiopulmonary bypass (CPB) hematocrit was 30%. We conclude that bloodless CPB surgery can be performed safely in Jehovah's Witness patients with a carefully planned interdisciplinary approach.

The Impact of Roller Pump vs. Centrifugal Pump on Homologous Blood Transfusion in Pediatric Cardiac Surgery.

Centrifugal pumps are considered to be less destructive to blood elements (1) when compared to roller pumps. However, their large prime volumes render them unsuitable as arterial pumps in heart lung machine (HLM) circuitry for children. In November of 2014, the circuit at Arnold Palmer Hospital, a Biomedicus BP-50 with kinetic assist venous drainage (KAVD) and 1/4″ tubing was converted to a roller pump in the arterial position with gravity drainage. Vacuum-assisted venous drainage (VAVD) was mounted on the HLM as a backup, but not used. Tubing was changed to 3/16″ in the arterial line in patients <13 kg. A retrospective study with a total of 140 patients compared patients placed on cardiopulmonary bypass (CPB) with Biomedicus centrifugal pumps and KAVD (Centrifugal Group, n = 40) to those placed on CPB with roller pumps and gravity drainage (Roller Group, n = 100). Patients requiring extra-corporeal membrane oxygenation (ECMO)/cardio-pulmonary support (CPS) or undergoing a hybrid procedure were excluded. Re-operation or circulatory arrest patients were not excluded. Prime volumes decreased by 57% from 456 ± 34 mL in the Centrifugal Group to 197 ± 34 mL in the Roller Group (p < .001). There was a corresponding increase in hematocrit (HCT) of blood primes and also on CPB. Intraoperative homologous blood transfusions also decreased 55% from 422 mL in the Centrifugal Group to 231 mL in the Roller Group (p < .001). The Society of Thoracic Surgeons--European Association for Cardio-Thoracic Surgery (STAT) categorized intubation times and hospital length of stay (LOS) for all infants showed a trend toward reduction, but was not statistically significant. Overall mortality was 5% utilizing the centrifugal configuration and 0% in the roller pump cohort. We demonstrated that the transition to roller pumps in the arterial position of the HLM considerably reduced our priming volume and formed a basis for a comprehensive blood conservation program. By maintaining higher HCTs on CPB, we were able to reduce intraoperative homologous blood transfusions.

Anatomical advantage to percutaneous insertion of the intra-aortic balloon through the left brachial artery over the right brachial artery.

Off-label use of the intra-aortic balloon (IAB) is not recommended in ideal situations and certainly not a Food and Drug Administration-approved activity. The instruction-for-use manual for the IAB recommends percutaneous insertion. However, there are certain extreme situations where "thinking outside the box" appears necessary. We have successfully inserted a transthoracic IAB (TIAB) in the operating room where an open sternum is an option. This has been instituted whenever severe peripheral vascular disease (PVD) precludes a percutaneous attempt or when attempted insertion fails. An open chest is not a choice in the catheterization laboratory or the postoperative setting. We have successfully inserted the IAB through the brachiall axillary artery in a patient with bilateral aortofemoral grafts, with a history of severe PVD, in the cardiac catheterization laboratory. A left-sided approach is advisable for brachial artery insertion and an axillary approach is also possible under sedation. This case report details our experience with transbrachial insertion of the IAB and establishes counterpulsation through this route as a viable option, where an open chest is not available and a percutaneous femoral approach has failed.

Trans-aortic counterpulsation: a viable alternative?

Transthoracic intra-aortic balloon pump (IABP) insertion has been a relatively rare and uncommon procedure. However, it is an established beneficial option in patients with severe peripheral vascular disease (PVD) accompanied with bi-lateral femoral arterial occlusion. There are several viable alternatives to trans-aortic IABP insertion, including trans-axillary or in abdominal aorta (requiring a laparotomy). Cardiac surgery has the advantage of an open sternum, facilitating effortless direct intra-aortic balloon (IAB) insertion into the aorta. The IAB can be inserted either through a 9-mm graft or directly into the ascending aorta. During cardiac surgery, direct insertion into the ascending aorta with the balloon tip lying distally in the abdominal aorta is facilitated with an open sternum. The base of the balloon lies approximately 2 cm below the left subclavian and can be confirmed through a trans-esophageal echocardiogram (TEE). Elimination of a graft insertion saves the team from time-consuming maneuvers and additional hemorrhagic complications. In our experience, postoperative vasoplegic syndrome coupled with myocardial edema contributed to patent instability and was treated with vasopressin and transthoracic IAB insertion. The CS 100 (Datascope Corp., Mahwah, NJ) console allowed the ability to time the balloon accurately. This case report details our experience with one such patient and establishes trans-aortic counter-pulsation as a safe and viable option in patients with severe PVD, where percutaneous insertion is precluded or has failed.