Acute and Short Term Hyperoxemia: How about Hemorheology and Tissue Perfusion?

Acute and Short Term Hyperoxemia: How about Hemorheology and Tissue Perfusion? Tissue perfusion is a major factor determining the prognosis, morbidity and mortality in ICU patients. Perfusion may carry on via uninterrupted delivery of sufficient substrate and oxygen to the tissues. From this point of view, determinants of tissue perfusion that routinely mentioned are cardiac output, vascular tonus, oxygen diffusion and transportation. The impact of blood viscosity and related hemorheological factors on microcirculation and tissue perfusion is frequently neglected. Under physiological circumstances, compensatory mechanisms maintain the stability of perfusion. However, it is well-established that the changes in aggregation and deformability of red blood cells are concomitant with alterations in blood fluidity at hypoxic conditions and this fact enhances the severity of hypoxemia. On the contrary, acute hyperoxemia is performed to achieve therapeutic goals or to prevent predicted hypoxemia during ICU facilities. Although the effects of hyperoxemia on vessel reactivity and ROS generation were previously indicated, its impact on hemorheology and tissue perfusion are not clear. Further studies are needed to disclose the influence of acute hyperoxemia performed during cardiopulmonary resuscitation, intubation, sedation, tracheal suction, etc., on tissue perfusion in critically ill patients.