Some authors refer to anaerobic metabolism as anaerobic respiration. This is an unfortunate term with regard to human physiology. In other organisms there are other types of energy metabolism that do not produce lactic acid and do not involve breathing. Doctors, nurses and others who encounter acidemia and the accumulation of lactate with anaerobic metabolism as it occurs in humans would find the term anaerobic respiration confusing. To most people particularly medical professionals respiratory or respiration refers to breathing and the consumption of oxygen not lacking oxygen as in an anaerobic (without oxygen) process.
Anaerobic metabolism, energy production in the form of ATP in humans and indeed all mammals produces lactic acid. This results in an acidemia resulting from the process of metabolic acidosis. The term anaerobic respiration should not be used in human physiology.
There are other forms of energy production particularly in anaerobic bacteria that don’t utilize oxygen and are anaerobic. These don ‘t involve breathing or respiration. A better term would be anaerobic oxidation in organisms that don’t have lungs and therefor don’t breath or respire. Fermentation occurs in yeast and should not refer to respiration.
Conditions in humans where anaerobic metabolism occurs from Cardiovascular Insufficiency
Strenuous exercise
Sepsis
Hemorrhagic Shock
Severe Dehydration
Some drug overdoses particularly methamphetamine.
The illnesses that are associated with anaerobic metabolism are primarily are cardiovascular conditions that produce low flow states. The flow of blood and the delivery of oxygen are impaired in these conditions leading to anaerobic metabolism supplementing but not replacing the normal aerobic metabolism for the production of energy. The decreased delivery of oxygen to highly metabolic tissues and organs is the primary cause of anaerobic metabolism in humans. The effect of anaerobic metabolism is that bicarbonate levels fall and pH decreases. There is generally a compensatory respiratory alkalosis with an increase in the depth and rate of breathing.
Arterial hypoxia is usually carefully monitored which is easy to do with modern technology. The saturation of oxygen is supported with supplemental oxygen and usually significant hypoxia of arterial blood is easily detected and avoided. Arterial hypoxia may cause or contribute to anaerobic metabolism if the support of arterial oxygenation begins to fail but the failure of perfusion is the more common cause of anaerobic metabolism.
It is often confusing that a cardiovascular condition causes an increase in the depth and rate of respiration and the perception of dyspnea. This is particularly the case in acute Cardiovascular Insufficiency which is commonly identified and mistakenly labeled as Flash Pulmonary Edema. This is a cardiovascular illness that causes severe dyspnea. The edema of the lungs commonly seen is the result of the illness not the cause.