«Although the terms hypoxia and hypoxemia are often used interchangeably, they are not synonymous. Hypoxemia is defined as a condition where arterial oxygen tension (Pao2) is below normal (normal Pao2 = 80–100mmHg). Hypoxia is defined as the failure of oxygenation at the tissue level.
It is not measured directly by a laboratory value (though an increased arterial lactate level usually accompanies tissue hypoxia). Hypoxia and hypoxemia may or may not occur together. Generally, the presence of hypoxemia suggests hypoxia. However, hypoxiamay not be present in patients with hypoxemia if the patient compensates for a low Pao2 by increasing oxygen delivery. This is typically achieved by increasing cardiac output or decreasing tissue oxygen consumption. Conversely, patients who are not hypoxemic may be hypoxic if oxygen delivery to tissues is impaired or if tissues are unable to use oxygen effectively. Nevertheless, hypoxemia is by far the most common cause of tissue hypoxia.»
«Abstract: Adequate oxygen supply to the tissues is of vital importance to survive critical illness and trauma. Shock can be defined as an imbalance between oxygen demand and oxygen supply. Clinical features of shock, like hypotension, tachycardia, cold clammy skin et cetera, are poorly correlated with presence of tissue hypoxia. A high lactate level is an early sign of tissue hypoxia. In severely ill patients tissue hypoxia is the most important cause of increasedlactate levels. Increased blood lactate levels are related to increasedmortality. Optimizing oxygen supply by fluid resuscitation is the intervention of first choice.»
Strong Magnitude of Effect.
Comments:«A high lactate level is an early sign of tissue hypoxia. In severely ill patients tissue hypoxia is the most important cause of increasedlactate levels. »