PATHOPHYSIOLOGY
A number of theories have been promulgated as to why MODS develops.
Hypoxia. Systemic hypoxia was initially advocated as the precipitating event
accounting for the development of organ dysfunction. Based on the pioneering work of
Rackow et al. [9], an attractive hypothesis has developed that patients with sepsis and
organ dysfunction (acute lung injury) have inadequate oxygenation. This explanation is
intuitively obvious for patients with hemorrhagic shock, cardiac arrest, etc. These conditions
are often readily reversible. For example, hemorrhagic shock is treated with transfusion
of red blood cells, and cardiopulmonary resuscitation is used for patients with cardiac
arrest, thus restoring oxygenation. In patients with sepsis, there is a more subtle oxygenation
deficit. In this condition, oxygen utilization often becomes dependent on oxygen
supply [11]. Decreased oxygen utilization, though, may be due to more than just an oxygen
delivery problem. Cellular processes may be involved [12]; to overcome the cellular
deficits, a higher oxygen gradient must be present at the mitochondrial level. Independent
of how the deficit develops, there is an increased body of evidence suggesting that
increasing oxygen supply by either increasing cardiac output or the oxygen-carrying content
of blood improves oxygen utilization and decreases morbidity and mortality.