From the Guidelines
Hypoxia and hypoxemia are distinct medical conditions, with hypoxemia referring to low oxygen levels in the blood and hypoxia describing inadequate oxygen supply to tissues and organs, which can result from hypoxemia or other causes. The key difference between the two conditions lies in their definitions and the factors that contribute to their development. Hypoxemia is specifically defined as a low arterial oxygen partial pressure (PaO2) or oxygen saturation (SaO2) 1, whereas hypoxia is a broader term that encompasses inadequate oxygen supply to tissues and organs. According to the BTS guideline for oxygen use in adults 1, hypoxemia can be caused by various mechanisms, including low PaO2, V/Q mismatch, and poor aeration of areas of the lung.
Hypoxia, on the other hand, can result from hypoxemia but also from other causes such as poor circulation, anaemia, or the inability of cells to use oxygen properly 1. The guideline suggests that sudden exposure to low SaO2 levels can cause impaired mental functioning, and most experts emphasize the importance of keeping the SaO2 above 90% for the majority of acutely ill patients 1. Some key points to consider when differentiating between hypoxia and hypoxemia include:
- Hypoxemia is a laboratory finding, typically defined as an arterial oxygen partial pressure (PaO2) below 80 mmHg or oxygen saturation (SaO2) less than 95% 1
- Hypoxia is a physiological state of oxygen deprivation in the body's tissues, which can be identified through clinical symptoms such as shortness of breath, confusion, rapid heart rate, or cyanosis
- The relationship between hypoxemia and hypoxia is important, as hypoxemia frequently leads to hypoxia if not corrected, but hypoxia can occur even with normal blood oxygen levels if there are problems with oxygen delivery or utilization at the tissue level 1.
From the Research
Definition and Difference
- Hypoxia refers to a condition in which the body or a region of the body is deprived of adequate oxygen supply [(2,3,4)].
- Hypoxemia, on the other hand, is a condition characterized by an abnormally low level of oxygen in the arterial blood [(2,3,5,6)].
Causes and Effects
- Hypoxia can be caused by various factors, including high altitude, anemia, or respiratory diseases, and can lead to tissue damage and organ dysfunction 4.
- Hypoxemia can be caused by respiratory problems, such as pneumonia or chronic obstructive pulmonary disease (COPD), and can lead to respiratory failure if left untreated [(2,3,5,6)].
Treatment and Management
- Treatment for hypoxia and hypoxemia typically involves increasing oxygen supply to the body, which can be achieved through oxygen therapy or mechanical ventilation [(2,3,5,6)].
- Non-invasive oxygenation strategies, such as high-flow nasal oxygen and helmet noninvasive ventilation, have been shown to be effective in reducing mortality and the need for invasive mechanical ventilation in patients with acute hypoxemic respiratory failure [(5,6)].