Main Difference – Hypoxia vs Hypoxemia
Hypoxia and Hypoxemia are two medical terms that are used to describe certain abnormalities of oxygen concentration at the tissue level and blood of our body. Hypoxia is defined as a reduction of oxygen supply at the tissue level whereas Hypoxemia is defined as a condition where arterial oxygen tension is measured to be between 80 and 100 mmHg. This is the main difference between hypoxia and hypoxemia.
1. What is Hypoxia?
– Signs and Symptoms, Causes, Prevention and Treatment
2. What is Hypoxemia?
– Signs and Symptoms, Causes, Treatment
3. What is the difference between Hypoxia and Hypoxemia? 
What is Hypoxia
This is defined as a condition in which body tissues are not adequately oxygenated due to an insufficient oxygen concentration in blood.
Signs and Symptoms of Hypoxia
Hypoxia can result in impaired metabolic activities in the body, leading to numerous signs and symptoms of compensatory mechanisms including
- Increased heart rate, heart muscle contractility and cardiac output.
- Shortness of breath, difficulty in breathing and wheezing
- Sweating and palpitation
- Cyanosis (bluish discoloration of mucosal membranes as a result of poor peripheral blood supply)
- Various skin colour changes such as blue, cherry red, etc. depending on the aetiology.
Causes of Hypoxia
Hypoxia is categorised into two types based on how extensively the tissues are affected by this poor oxygen supply.
– Localised hypoxia affecting a specific area of the body, particularly the face or limbs.
– Generalised hypoxia which involves the whole body and sometimes called Anoxia where there is a complete deprivation of oxygen-rich blood supply, all throughout the body.
Hypoxia can be also be caused by several different pathologies like anaemia, where there is a reduced amount of functional haemoglobin resulting in a reduction of blood’s oxygen carrying capacity. Furthermore, various congenital and acquired heart defects, valvular dysfunction and lung diseases such as COPD, emphysema, bronchitis, pulmonary edema can result in hypoxia.
Carbon monoxide poisoning can also give rise to hypoxia since this gas has a higher potential of getting attached to haemoglobin when compared to that of oxygen, giving rise to complications such as cardiac failure or myocardial infarction.
Hypoxia can also be observed in completely healthy individuals, who are living in high altitudes. This is mainly due to a lowered partial pressure of oxygen in inhaled air. This can be severe and life threatening, resulting in complications such as high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE).
Prevention of Hypoxia
Prevention from hypoxia mainly depends on the aetiology and may vary from avoiding triggering factors to getting treated for underlying risk factors with appropriate medical or surgical therapy.
- Keeping respiratory conditions such as asthma under control by being compliant on drugs.
- Engaging in routine physical exercises
- Consumption of a well-balanced diet
- Getting treatments for underlying conditions like cardiac diseases, lung diseases and Anemia
- Being aware of signs and symptoms associated with hypoxia, in order to get medical advice when necessary
Cerebral hypoxia
What is Hypoxemia
Hypoxemia is defined as a condition characterised by a reduction of arterial oxygen tension or partial pressure of oxygen below 80-100 mmHg. This is mostly seen in individuals with predisposing cardiac or respiratory illnesses as well as in chronic smokers.
Commonest Causes of Hypoxemia:
- Chronic obstructive pulmonary disease (COPD)
- Airway obstruction (foreign bodies, anatomical abnormalities)
- Acute respiratory distress syndrome
- Pneumonia
- Pneumothorax
- Emphysema
- Congenital heart defects and valvular dysfunction
- Pulmonary embolism and edema
Signs and Symptoms of Hypoxemia
Most patients with Hypoxemia will experience shortness of breath (dyspnea), restlessness, anxiety, headaches and other minor alterations of the mental status since the level of oxygen supply to brain and lungs get hugely impaired. Some individuals can also experience cyanosis, acute hypertension, tachycardia (heart rate more than 100/min) and tachypnea (respiratory rate more than 24/min), depending on the overall effectiveness of body’s compensatory mechanisms.
Treatment for Hypoxemia
Once the condition is diagnosed with vital signs described above and associated clinical history, the condition can be managed depending on the severity.
Major modalities of intervention include
- Mechanical ventilation
- Supplemental oxygen therapy
- Transfusion of packed red blood cells
A basic oxyhaemoglobin (oxyhemoglobin) dissociation curve
Difference Between Hypoxia and Hypoxemia
Definition
Hypoxia is defined as a reduction of oxygen supply at the tissue level, which is not measured directly by a laboratory value
Hypoxemia is defined as a condition where arterial oxygen tension or partial pressure of oxygen (PaO2) is measured to be between 80 and 100 mmHg.
Relationship
Most patients with Hypoxemia will experience Hypoxia except for some minority of cases which are handled with an efficient bodily compensatory mechanism by increasing the cardiac output or decreasing body’s oxygen demand.
On the other hand, patients with hypoxia don’t have to be necessarily present with signs of hypoxemia especially when the delivery of oxygen to tissues become hampered or tissues are unable to use available oxygen in an efficient manner.
However, hypoxemia is known to be the commonest cause for Hypoxia and therefore it is important to understand the features of both conditions in order to make an accurate diagnosis to carry out proper and prompt treatments.
Image Courtesy:
“Arteries beneath brain Gray closer” By Wikid77 – Derivative of Image:Gray516.png (Public Domain) via Commons Wikimedia
“Oxyhaemoglobin dissociation curve” By Ratznium at English WikipediaLater versions were uploaded by Aaron Sharpe at en.wikipedia. – Transferred from en.wikipedia to Commons. (Public Domain) via Commons Wikimedia
