Our bodies require a precise balance of oxygen to function correctly. While a lack of oxygen, known as hypoxia, can be dangerous, an excess of oxygen can also pose significant health risks. This abundance of oxygen leads to a state that is the direct opposite of oxygen deprivation.
Understanding Hyperoxia
Hyperoxia is the condition characterized by abnormally high levels of oxygen in the body’s tissues or blood. This state occurs when the partial pressure of oxygen in the alveoli, the tiny air sacs in the lungs, becomes greater than what is typically found when breathing normal air at sea level.
For healthy adults at sea level, normal arterial oxygen pressure (PaO2) ranges from 75 to 100 millimeters of mercury (mmHg). Blood oxygen saturation (SpO2), which measures the percentage of oxygen bound to hemoglobin, falls between 95% and 100%. While oxygen is necessary for life, maintaining these levels within an optimal range is crucial, as exceeding them can lead to various physiological consequences.
When and Why Oxygen Levels Become Elevated
Elevated oxygen levels occur in controlled medical environments where high concentrations of oxygen are administered. A common scenario involves supplemental oxygen therapy, used to increase oxygen delivery to tissues, particularly in patients experiencing respiratory distress or during surgical procedures. This therapy can involve administering oxygen via nasal cannula or ventilators.
Another significant context is hyperbaric oxygen therapy (HBOT), a specialized treatment where individuals breathe nearly 100% oxygen within a pressurized chamber set above normal atmospheric pressure. HBOT increases the amount of dissolved oxygen in the blood. Less common scenarios leading to hyperoxia include certain diving accidents, where divers breathe gas mixtures with a high oxygen fraction at increased ambient pressures.
How Elevated Oxygen Levels Impact the Body
Controlled hyperoxia, particularly through hyperbaric oxygen therapy, can offer therapeutic benefits. It increases dissolved oxygen in the blood, which can help reverse tissue hypoxia and promote angiogenesis. This increased oxygen can also modulate inflammation, offering advantages in treating conditions like severe infections, carbon monoxide poisoning, and non-healing wounds.
Conversely, excessive oxygen can be toxic, a condition known as oxygen toxicity. The effects depend on the oxygen level, duration of exposure, and individual susceptibility. In the lungs, pulmonary oxygen toxicity can lead to inflammation and reduced lung function. Symptoms can include pleuritic chest pain, coughing, and shortness of breath.
The central nervous system (CNS) can also be affected, leading to CNS oxygen toxicity. Symptoms may include headaches, dizziness, visual changes, nausea, muscle twitching, and even seizures. In infants, particularly premature newborns, prolonged exposure to high oxygen levels can lead to retinopathy of prematurity.