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.

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

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

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.

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.

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