Safety Testing of Left Ventricular Vent Valves.

Vent vacuum relief valves (VRVs) are used to limit the negative pressure at the ventricular vent catheter tip as well as prevent reversal of blood flow and prevention of air embolism. The purpose of this study was to evaluate the performance of three commercially available ventricular vent valves. The negative pressure at which the vent valve opened was measured at the valve inlet using high-fidelity pressure transducers. Also, the flow rate at which air entrainment occurred due to valve opening was recorded. Using a 51.5 cm column of saline, the resistance for each valve was calculated. The mean ± SD opening negative pressures were -231.3 ± 35.2 mmHg for the Quest Medical valve, -219.8 mmHg ± 17.2 for the Sorin valve, and -329.6 · 38.0 mmHg for the Terumo valve. The red Quest Medical valve opened at a lower flow (1.44 ± .03 L/min) than the dark blue Sorin valve (2.93 ± .01 L/min) and light blue LH130 Terumo valve (2.36 ± .02 L/min). The Sorin valve had the least resistance of 34.1 dyn-s/cm, followed by the Terumo LH130 valve resistance of 58.1 dyn·s/cm5, and the Quest Medical VRV-II valve with a resistance of 66.5 dyn·s/cm. We found that the valves are significantly different in the negative pressure generated. Understanding the limitations of these devices is important to reduce the occurrence of adverse events associated with venting and to select the best device for a specific clinical application.

Professionalism as a perfusion problem.

Perfusion has existed as a vocation for 50 years and has been officially recognized as an allied health profession since 1976. As a profession, perfusion holds a social contract within society defined in part by its Code of Ethics. There is very little that has been written to explore whether perfusion is a profession in the sense of a "learned profession" or if perfusionists function as professionals. This article provides evidence that perfusion is a profession in the classic interpretation and that the practitioners of this profession are professionals in the global sense. As is true in all professions, individuals have free will to conduct their behaviors in a professional manner or not. There are challenges to the professional status of perfusion on several levels, some of which we will discuss, and offer possible solutions. It takes an effort on the part of a profession to gather, maintain, and increase their professionalism. The profession of perfusion is not exempt from this and is discussed in that light.

Cardiopulmonary bypass with bivalirudin in type II heparin-induced thrombocytopenia.

Cardiopulmonary bypass in patients with type II heparin induced-thrombocytopenia poses significant challenges. Inadequate pharmacokinetic profiles, monitoring, reversibility, and availability often limit alternative anticoagulation strategies. Bivalirudin, a semisynthetic direct thrombin inhibitor, was recently approved for use in patients undergoing percutaneous coronary interventions. Its unique properties, including a relatively short half-life, an anticoagulation effect that closely correlates with activated clotting time, and an alternate metabolic pathway for elimination, make bivalirudin an attractive agent for cardiopulmonary bypass in patients with type II heparin induced-thrombocytopenia. We report our experience using bivalirudin in 2 patients undergoing coronary artery bypass grafting.

Fresh frozen plasma in the pediatric pump prime: a prospective, randomized trial.

BACKGROUND: The aim of this study was to determine whether the use of fresh frozen plasma (FFP) in the infant pump prime can avoid dilution of fibrinogen, decrease the need for blood product transfusion after bypass, and decrease exposure to donor blood products. METHODS: Twenty infants weighing less than 8 kg were prospectively randomized to receive either 1 U of FFP (10 patients) or no FFP (10 patients) in the pump prime. Mean age (4.2 +/- 2.8 months), weight (4.3 +/- 1.1 kg), total prime volume (641 +/- 96 ml), cardiopulmonary bypass time, cross-clamp time, lowest temperature on bypass, and preoperative coagulation parameters did not differ between the two groups. RESULTS: At the end of bypass, the mean fibrinogen level was significantly higher in the FFP than the no FFP group (123 +/- 20 versus 58 +/- 17 mg/dL; p < 0.0001), whereas the mean platelet count did not differ (60 +/- 25 versus 52 +/- 26 K/mm(3); p = 0.5). Patients in the FFP group received significantly fewer units of cryoprecipitate (0.4 +/- 0.8 versus 2.0 +/- 0.9 U/patient; p < 0.001), and had a mean total donor exposure of 4.1 +/- 1.5 U/patient versus 5.4 +/- 1.4 U/patient in the no FFP group (p = 0.06). The mean chest tube output over the first 24 hours did not differ between groups. CONCLUSIONS: The use of FFP in the pump prime significantly limited dilutional hypofibrinogenemia, decreased the transfusion of cryoprecipitate after bypass, and tended to decrease the overall mean patient exposure to blood products.

The effectiveness of low-prime cardiopulmonary bypass circuits at removing gaseous emboli.

During extracorporeal circulation, the patient's blood is siphoned into the extracorporeal circuit (ECC) by gravity or may be assisted kinetically or by vacuum. In all instances, negative pressure is generated in the venous line, which can cause entrainment of air into the ECC at the cannulation site. The typical ECC uses a venous reservoir, membrane oxygenator, and arterial line filter, which together aid in removal of air that has entered the venous line and minimize the transmission of gaseous microemboli to the patient. Recently, several manufacturers have introduced low prime ECCs with component configurations that differ from conventional ECCs, including the omission of a venous reservoir. These configuration changes may change the ability of the circuit to handle air and therefore their ability to minimize gaseous microemboli. The purpose of this study was to test the ability of new low prime ECCs to remove air introduced into the venous line and minimize gaseous microemboli from entering the patient's circulation. Using a model of CPB, air was introduced into the venous line of a low prime ECC and a conventional CPB circuit. The detection of the gaseous microemboli produced was monitored distal to the oxygenator by an ultrasonic emboli detector to determine if venous air was able to traverse the ECC at varying rates of air introduction and blood flow. Data was collected using data acquisition software loaded on a personal computer. Gaseous microemboli levels detected in the arterial line of the low prime ECC were 8 to 10 times higher than the microemboli levels detected in the conventional ECC at all blood flow rates. Every effort should be made to minimize and prevent air from being entrained in the venous line of a low prime CPB circuit to minimize the risk of arterial gaseous microemboli generation.

pH-stat ventilation management: a simple method of achieving this regimen.

Since the advent of extracorporeal circulation for life support during cardiac surgery, there have been varied opinions as to the best method of ventilating an oxygenator to achieve the optimum arterial blood gas. With respect to the optimum pCO2, clinical investigators have focused primarily on the pros and cons of the alpha-stat and pH-stat ventilation schemes. pH-stat is a ventilation scheme that attempts to maintain the temperature corrected pH of the arterial blood at 7.40, no matter what the actual temperature of the blood. This paper does not attempt to elucidate the benefits of one scheme over the other, but is offered to provide perfusionists with a simple method of achieving pH-stat ventilation, using a CO2 source and materials readily available in any operating room. Strict adherence to a few cautionary notes should enable any perfusionist to safely deliver pH-stat ventilation when indicated. This technique of providing pH-stat ventilation has been used at our institution for over three years. It has proven to be easy to accomplish, adjust and maintain.