Low oxygen saturation, also known as hypoxia, refers to a shortage of oxygen within the body. Hypoxia can be classified as generalised hypoxia, resulting when the entire body is denied of oxygen, or tissue hypoxia, caused by dearth of oxygen in a specific body section or region. It results from inadequate oxygen supply to the body which leads to a drop in the partial pressure of oxygen within the arterial blood. Normal oxygen saturation ranges between 96 per cent to a 100 per cent whereas a percentage below 90 can cause life-threatening complications.
Cyanosis is attributed to the un-oxygenated haemoglobin levels within the capillaries that exceed 5g/dl leading to fingernail beds, mucosal membrane, skin pigment and sometimes the nose, ears and feet turning blue. The blue pigment is easily visible when the oxygen levels of the body fall below 90 per cent. Cyanosis can also be attributed to the presence of abnormally high methemoglobin (metHb) which prevents metHb from binding with oxygen, lowering the oxygen saturation.
When the availability of oxygen reaching the brain is obstructed, it decreases the level of consciousness and attention and leads to uncoordinated movement. Further reduction of oxygen availability in the brain can cause cerebral hypoxia that can result in a coma, which is a complete loss of awareness. Other symptoms of cerebral hypoxia such as lack of response to light and poor breathing can arise from severe reduction of oxygen saturation in the brain.
When the body experiences low oxygen saturation, blood is directed to the vital organs such as the heart, brain and the lungs, leading to the decrease in digestion and absorption of food in the gastrointestinal tract, thus compromising its core function. Disturbance of the digestive system as a result of hypoxia will cause people to feel nauseated and suffer from loss of appetite. Slow absorption and breakdown of food in the gastrointestinal tract as a result of hypoxia can cause vomiting.
When the body experiences hypoxia, it automatically comes up with various coping mechanisms to deal with the situation. Depth and rate of breathing are increased to help deliver more oxygen to the lungs. Pulse rate increases as a result of the heart's pumping blood faster so as to increase the level of oxygen being supplied to tissues. All of these adaptations manifest in rapid breathing as the body tries to make up for the oxygen deficit in the system. The body can accommodate these adaptations only for a limited time, which necessitates supplemental oxygen.
Treatment of Hypoxia
Hypoxia is often treated by giving patients supplemental oxygen, commonly referred to as oxygen therapy. People suffering from hypoxia are hospitalised and placed on a mechanical ventilation to assist in breathing. The vital signs of blood pressure, respiratory rate, temperature and heart rate are monitored constantly. Cold blankets can help slow down the brain cell activity, decreasing the demand for extra oxygen. However, the underlying cause of hypoxia should be treated to prevent future occurrences.
- Mayo Clinic; Hypoxemia (Low Blood Oxygen); 2010
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- Sleep Apnea; Sleep Apnea Symptoms; 2010
- National Outdoor Leadership School; Altitude Illness; 1991
- Flight Station; Hypoxia, Oxygen and Pulse Oximetry; Fred Furgang, MD