Thus any cause that influences the rate or volume of air entering the lungs (ventilation) or any cause that influences the transfer of air from the lungs to the blood may cause hypoxemia. As well as these respiratory causes, cardiovascular causes such as shunts may also result in hypoxemia. Hypoxemia is caused by five categories of etiologies: hypoventilation, ventilation/perfusion mismatch, right-to-left shunt, diffusion impairment, and low PO2. Low PO2 and hypoventilation are associated with a normal alveolar–arterial gradient (A-a gradient) whereas the other categories are associated with an increased A-a gradient. : 229

Ventilation
If the alveolar ventilation is low, there will not be enough oxygen delivered to the alveoli for the bodys use. This can cause hypoxemia even if the lungs are normal, as the cause is in the brainstems control of ventilation or in the bodys inability to breathe effectively. Respiratory drive
Respiration is controlled by centers in the medulla, which influence the rate of breathing and the depth of each breath. This is influenced by the blood level of carbon dioxide, as determined by central and peripheral chemoreceptors located in the central nervous system and carotid and aortic bodies, respectively. Hypoxia occurs when the breathing center doesnt function correctly or when the signal is not appropriate:

Strokes, epilepsy and cervical neck fractures can all damage the medullary respiratory centres that generates rhythmic impulses and transmit them along the phrenic nerve to the diaphragm, the muscle that is responsible for breathing.
These results suggest that 5-HT7 receptor antagonism mediates the antidepressant effects of amisulpride.Amisulpride also appears to bind with high affinity to the serotonin 5-HT2B receptor (Ki = 13 nM), where it acts as an antagonist. The clinical implications of this, if any, are unclear. In any case, there is no evidence that this action mediates any of the therapeutic effects of amisulpride.Amisulpride shows stereoselectivity in its actions. Aramisulpride ((R)-amisulpride) has higher affinity for the 5-HT7 receptor (Ki = 47 nM vs. 1,900 nM) while esamisulpride ((S)-amisulpride) has higher affinity for the D2 receptor (4.0 nM vs. 140 nM). An 85:15 ratio of aramisulpride to esamisulpride (SEP-4199) which provides more balanced 5-HT7 and D2 receptor antagonism than racemic amisulpride (50:50 ratio of enantiomers) is under development for the treatment of bipolar depression. Society and culture
Brand names
Brand names include: Amazeo, Amipride (AU), Amival, Solian (AU, IE, RU, UK, ZA), Soltus, Sulpitac (IN), Sulprix (AU), Midora (RO) and Socian (BR). Availability
Amisulpride was not approved by the Food and Drug Administration for use in the United States until February 2020, but it is used in Europe, Israel, Mexico, India, New Zealand and Australia to treat psychosis and schizophrenia.An IV formulation of Amisulpride was approved for the treatment of postoperative nausea and vomiting ("PONV") in the United States in February 2020. History
The U.S. Food and Drug Administration (FDA) approved amisulpride based on evidence from four clinical trials of 2323 subjects undergoing surgery or experiencing nausea and vomiting after the surgery.