Anemic hypoxia is seen in -
Ans. is 'd' i.e., Co poisoning o Hypoxia is a state in which tissues suffer from oxygen deficiency, i.e., O2 deficiency at tissue level. Depending on the cause it is generally divided into four categories: -1) Hypoxic hypoxia# If hypoxia is due to a decrease in oxygen supply, it is called hypoxic hypoxia.# There is a fall in PO2 of arterial blood and there is low O2 content.# Hypoxic hypoxia is the most common type of hypoxia.# Hypoxic hypoxia is seen in hypoventilation (e.g., in restrictive lung diseases, COPD etc), reduced oxygen diffusion capacity of lung, high altitude, V/Q mismatch and right to left shunt (e.g., cyanotic CHD or AV malformation).2) Anemic hypoxia# If hypoxia is due to a decrease in the oxygen carrying capacity of blood, it is called anemic hypoxia. Since almost the entire oxygen transported by blood is in combination with hemoglobin, the oxygen carrying capacity of blood is reduced in anemia; hence the term anaemic hypoxia.# The O2 content of blood is low despite normal PO2. This is due to low oxygen saturation of hemoglobin.# Similar situation also arises in carbon monoxide poisoning because carbon monoxide has a much greater affinity for hemoglobin than oxygen. In carbon monoxide poisoning, carbon monoxide uses up the hemoglobin by combining with it, thereby leaving very little hemoglobin for combining with oxygen. Therefore the situation is similar to anemia where the hemoglobin level of blood is low. That is why the hypoxia produced by CO poisoning is also called anaemic hypoxia.# As PO2 is normal, respiration is not stimulated by anemic hypoxia. This is because peripheral chemoreceptos are sensitive only to PO2.3) Stagnant hypoxia (Hypoperfusion hypoxia)# This type of hypoxia occurs because of sluggish blood flow, e.g., in CHF or circulatory shock.# In the arterial blood PO2 and oxygen content are normal. However, the volume of blood flow in the tissues per minute is reduced.# The venous blood contains larger amount of deoxygenated hemoglobin, because of greater O2 extraction, as blood stays in the capillaries for a longer time than normal due to sluggish blood flow.# Therefore, cyanosis is a prominent feature. Arterio-venous O2 difference (A-V O2 difference) is maximum in stagnant hypoxia.4) Histotoxic hypoxia# This type of hypoxia results because the tissues are unable to use the oxygen brought to them by blood, i.e., tissues suffer from hypoxia despite an adequate delivery of O2.# Arterial blood PO2 and oxygen content are normal.# The best example of histotoxic hypoxia is cyanide poisoning which inhibits cytochrome oxidase. Therefore, O2 cannot be utilized by tissues due to inhibition of oxidative metabolism. In Histotoxic hypoxia (e.g, cyanide poisoning), A-V O2 difference is markedly reduced and it may be zero.
Cyanide poisoning
COPD
High altitude
Co poisoning
Applied Aspects and Respiratory Adjustments