Recent Advances in Artificial Blood Substitutes & Oxygen Carriers

Abstract

B lood is a specialized body fluid that delivers necessary substances to the body's cells – such as nutrients & oxygen – & transports waste products away from those same cells. It consists of cellular & non-cellular parts. Cellular part includes Red Blood Cells (RBCs), White Blood Cells (WBCs) & platelets; while the non-cellular part is the plasma. Blood accounts for 8% of the human body weight; the average adult has a blood volume of roughly 5 liters. The most important function of the red blood cells is to carry the oxygen molecules. The Mammalian life depends on a continuous supply of oxygen to sustain aerobic metabolism. Reduced oxygen delivery & failure of cellular use of oxygen occur in various circumstances & if not recognized; result in organ dysfunction & death. Although oxygen is the substrate that cells use in the greatest quantity & on which aerobic metabolism & cell integrity depend, the tissues have no storage system for oxygen. They rely on a continuous supply at a rate that precisely matches changing metabolic requirements. Oxygen transport from environmental air to the mitochondria of individual cells occurs as a series of steps were the heart, lungs & circulation extract oxygen from the atmosphere & generate a flow of oxygenated blood to the tissues to maintain aerobic metabolism; while at the tissue level, cells must extract oxygen from the extracellular environment & use it efficiently in cellular metabolic processes. Complications of blood transfusion are rare but can be life-threatening. Since 2005, it has been a legal requirement that all serious adverse reactions attributable to the safety or quality of blood are reported. Most of reported complications are because of transfusion of mismatched blood products & are avoidable through clinical vigilance. Moreover, Massive blood transfusions result in abnormalities of coagulation status, serum biochemistry, acid–base balance & temperature homeostasis. However, Transfusion-related acute lung injury (TRALI) is the most common cause of major morbidity & death after transfusion. Serious complications of blood transfusion have been documented. Although immunologically mediated reactions to transfusion products are potentially serious, anaesthetists are most likely to encounter those relating to massive blood transfusion & transfusion-related acute lung injury (TRALI). These adverse events are of most relevance to our profession. Safe & effective artificial oxygen carriers are the subject of great interest due to the problems of traditional blood transfusion & enormous demand in clinical use. A blood substitute is a substance used to mimic & fulfill some functions of biological blood. It aims to provide an alternative to blood transfusion, which is transferring blood or blood-based products from one person into another. There are widely available non-blood volume expanders