Cardiorespiratory effects of venous lipid micro embolization in an experimental model of mediastinal shed blood reinfusion

Seven adult pigs were used. A shed blood surrogate containing 400 ml diluted blood and 5 ml radioactive triolein was produced to generate a lipid embolic load. The shed blood surrogate was rapidly (<2 minutes) retransfused from a transfusion bag to the right atrium under general anesthesia. The animals' arterial, pulmonary, right and left atrial pressure were monitored, together with cardiac output and deadspace. At the end of the experiment, an increase in cardiac output and pulmonary pressure was pharmacologically induced to try to flush out lipid particles from the lungs.A more than 30-fold increase in pulmonary vascular resistance was observed, with subsequent increase in pulmonary artery pressure, and decrease in cardiac output and arterial pressure. This response was transient, but was followed by a smaller, persistent increase in pulmonary vascular resistance. Only a small portion of the infused triolein passed the lungs, and only a small fraction could be recirculated by increasing cardiac output and pulmonary pressure.Infusion of blood containing lipid micro-emboli on the venous side leads to acute, severe hemodynamic responses that can be life threatening. Lipid particles will be trapped in the lungs, leading to persistent effects on the pulmonary vascular resistance.Autotransfusion of blood is used in surgical procedures to reduce the need for allogenic blood transfusion. The main reasons for doing this are to reduce costs and transfusion-related morbidity. Adverse effects of heterologous transfusions have recently been highlighted [1]. For example, it has been shown in cardiac surgery that heterologous blood transfusion may have negative effects on long-term survival [2,3].In addition to autotransfusion, blood conservation strategies are employed routinely in several surgical procedures. In cardiac surgery, for example, blood lost in the pericardium or pleurae is routinely retransfused directly to the patient via the heart-lung machine. Sometimes, a cent