Effect of liposome encapsulated hemoglobin "neo red cells" on severe hemorrhagic shock.

We induced shock by exsanguination and administered Neo Red Cells (NRC) after 30 minutes to experimentally examine the efficacy of NRC on severe shock with respect to hemodynamics and oxygen transport capacity. Seven beagles were used for this experiment. After intravenous anesthesia, intratracheal intubation was performed, and inhalation of 50% oxygen was administered. Animals were exsanguinated through a vein at a rate of 30 mL/min. Animals showing systolic blood pressure of 60 to 69 mmHg were regarded as being in shock. After animals were left untreated for 30 minutes, NRC was administered. This was then repeated. Administration of NRC at a 1.5-fold dose compared to the exsanguinated blood volume was required for animals to recover from shock. Animals tolerated shock 3 times, but did not recover from the 4th shock. Although NRC with approximately one third the viscosity of whole blood was administered, vascular resistance was increased and cardiac output was decreased, resulting in progression of heart failure. In addition, oxygen consumption increased with shock. NRC satisfied oxygen requirements by compensating for the decrease in cardiac output with an increase in AV difference, but erythrocytes were insufficient to increase difference in arterial and venous oxygen content (AV difference), and did not supply sufficient volume of oxygen.