When blood is lost, the greatest immediate need is to stop further blood loss. The second greatest need is replacing the lost<unk> . This way remaining red blood cells can still oxygenate body tissue. Normal human blood has a significant excess oxygen transport capability, only used in cases of great physical exertion. Provided blood<unk>  is maintained by<unk> s, a rested patient can safely tolerate very low hemoglobin levels, less than 1/3 that of a healthy person. The body detects the lower hemoglobin level, and compensatory mechanisms start up. The heart pumps more blood with each beat. Since the lost blood was replaced with a suitable fluid, the now diluted blood flows more easily, even in the small vessels. As a result of chemical changes, more oxygen is released to the tissues. These adaptations are so effective that if only half of the red blood cells remain, oxygen delivery may still be about 75 percent of normal. A patient at rest uses only 25 percent of the oxygen available in their blood. In extreme cases, patients have survived with a hemoglobin level of 2 g/dl, about 1/7 the normal, although levels this low are very dangerous. With enough blood loss, ultimately red blood cell levels drop too low for adequate tissue oxygenation, even if<unk> s maintain circulatory<unk> . In these situations, the only alternatives are blood transfusions, packed red blood cells, or oxygen therapeutics (if available). However, in some circumstances, hyperbaric oxygen therapy can maintain adequate tissue oxygenation even if red blood cell levels are below normal life-sustaining levels.
Volume expander
Osmotic dilator
Catheter lock solution
Saline flush
Contrast agent
Diuresis
Iodixanol
Uterotonic