Low blood oxygen levels or hypoxemia can be caused by an airway blockage, anemia, acute respiratory distress or heart ailments, among other conditions, according to Mayo Clinic. Lung disease and cyanide poisoning can also cause hypoxemia, states WebMD.
Hypoxemia due to anemia is caused when there isn't an adequate number of red blood cells in the body to carry oxygen to the organs and tissues, according to WebMD. Acute respiratory distress syndrome occurs when fluids build up in the lung sacs. The greater the fluid accumulation, the lesser the amount of oxygen that is reaching the blood. This condition develops soon after the patient has suffered some serious trauma or injury. Shortness of breath is among the earliest symptoms.
Emphysema damages the clusters of air sacs in the lungs by breaking down their inner walls and fusing them into a large mass, notes Mayo Clinic. This reduces the surface area of each lung and in turn cuts down on the amount of oxygen reaching the blood. Emphysema is one of a number of conditions that are grouped under chronic obstructive pulmonary disease, according to Mayo Clinic Other causes of low oxygen content in the blood are cyanide poisoning and strong pain medications.