1. DEFINITION
HYPOXIA: A condition in which the oxygen available is inadequate at the tissue level
Five types of hypoxia:
Anemic
Hypoxemic
Histotoxic
Circulatory
Hypermetabolic
In this condition, there are anaerobic mechanisms that are activated at the tissue level that produce waste products such as lactate and hydrogen ions which are detrimental to the body.

2. Anemic Hypoxia
Having a decreased carrying capacity for oxygen, the pt with decreased or abnormal Hb
Anemia
Carbon monoxide poisoning
Methemoglobinemia
Sickle Cell Anemia
Treatment involves blood transfusions, hyperbaric chamber, bone marrow transplant
In this type of hypoxia, there can be an adequate amount of oxygen available in the arterial blood, but the problem is the lack of hemoglobin a protein in our RBCs or the inability to carry oxygen
Anemia is having a low blood count, the oxygen is unable to reach the body because the number of blood cells is low in the body.
Carbon monoxide poisoning is very commonly seen especially because carbon monoxide is undetectable unless you have alarms in your house. Also related to smoking.
Carbon monoxide has an affinity for hemoglobin that is 210x greater than oxygen. Therefore the CO will cling to the RBC before the oxygen can.
Methemoglobinemia is a condition in which iron atoms oxidize into a ferric state which eliminate the ability for hemoglobin to carry oxygen. Can be seen in patients receiving iNO.
Red blood cells are normally circular shaped and the oxygen can bind with the cell
Sickle cell anemia is a genetic condition in which the patient produces hemoglobin that is shaped like sickle or banana-shaped. Results in the inability to carry oxygen which lead to hypoxia and pain crises

3. Hypoxemic Hypoxia Low PAO2 due to the atmosphere
Hypoventilation – PCO2 is rising
Diffusion Defects
The PaO2 will be lower in all cases, but the PCO2 may or may not be increased.
Treatment: Compensatory actions to reduce inequalities, supplemental oxygen
Aka – hypoxemic hypoxia
Clinically called hypoxemia or low oxygen concentration in the blood
Low PaO2
Certain diseases that can cause hypoventilation causing the patient to not breathe the amount of oxygen necessary to maintain good oxygen levels in the blood
Drug overdose
Neuromuscular diseases that affect the respiratory muscles ex-myasthenia gravis
COPD – asthma, bronchitis, cystic fibrosis, emphysema
V/Q mismatch – occurs when the pulmonary capillary blood flow (the blood that flows through the lungs) exceeds alveolar ventilation (when gas exchange occurs between the alveoli – the sacs in the lung – and the blood going to the heart and then the rest of the body)
When this occurs you have far more red blood cells that are not carrying oxygen causing this hypoxic hypoxia
Diffusion defects – occur with certain pulmonary diseases where the time available for oxygen to be exchanged is inadequate
Interstitial fibrosis
Alveolar consolidation
Interstitial or alveolar edema

4. Histotoxic Hypoxia Inability for tissues to utilize oxygen available
Cyanide Poisoning will inhibit cellular metabolism from occuring; the cells can not process the O2
Treatment: Reversal of poisoning, supplemental oxygen and/or ventilation
Previously talked about problems with the blood, problems caused by respiratory or ventilation issues.
Histotoxic Hypoxia is the inability of the tissue to use the oxygen that is available.
Cyanide poisoning is commonly seen from smoke inhalation when materials such as silk and plastic is burned.
This is the most common cause for histotoxic hypoxia.
poisoning that blocks the enzymes that involved in the use of oxygen in the cells.

5. Circulatory Hypoxia
A decrease in cardiac output results in a low BP and a prolonged systemic transit time
The PaO2 can be high, but because of the time it takes to get to the tissues, the pt is hypoxic
Cardiovascular instability or failure
Shock
Arrhythmias
Treatment include increasing cardiac output with use of cardiovascular drugs and therapy, supplemental oxygen
This type of hypoxia is associated with cardiac issues.
Because the heart is malfunctioning, the blood flows sluggishly. When this happens the time needed for gas exchange at the tissue level is increased and at the same time the oxygen supply depletes.

6. Hypermetabolic Hypoxia
In some disease states the body requires a slight increase in metabolism (i.e. – wound healing requires 5% increase)
Extensive burns and some cancers will cause large increases metabolism to the point that supplemental O2 is required
Treatment: Supplemental O2 or FiO2