Nausea and vomiting after surgery

The term PONV is commonly used to describe nausea or vomiting in the post-anesthesia care unit (PACU) or in the 24-hour period following surgery. This is important because post-surgery nausea, vomiting and anesthetic procedures can affect post-operative recovery. Fortunately, PONV is usually easily treated, but in some cases, the patient may need to stay in the hospital or be discharged from the hospital later than usual. In addition, vomiting can lead to wound damage, esophageal injury and rupture, aspiration, dehydration, increased intracranial pressure, and pneumothorax.

Terms such as post-discharge nausea and vomiting (PDNV[3]) refer to symptoms that occur due to post-discharge procedures. Postoperative vomiting (POV[4]) is more commonly studied in children than PONV, as nausea is more difficult to assess in young children.

Pathophysiology

Several central and peripheral mechanisms are involved in nausea and vomiting. The five types of receptors associated with the main neurotransmitters involved in nausea and vomiting include: muscarinic M1, dopamine D2, histamine H1, serotonin (5HT)-3, and neurokinin 1 (NK1) receptors (Substance P). All these receptors can be effective in the prevention or treatment of PONV.

• Central mechanisms: due to the connection of the cerebral cortex with the center of nausea and vomiting, any fear, pain, and anxiety can cause nausea and vomiting by stimulating the cerebral cortex after the operation.
• Environmental mechanisms: direct stimulation of the stomach through mechanical damage, blood, or toxins can lead to the release of substance P and serotonin from enterochromaffin cells, thereby activating serotonin receptors (5HT3), vagal nerves, and splanchnic nerves. The ends of these nerves are located in the brain stem in the vicinity of the postrema area, which is called the chemoreceptor stimulation zone (CTZ[5]). Intestinal surgery and blood in the gastrointestinal tract resulting from oral or ear, nose, and throat surgeries may cause nausea and vomiting through this pathway, however, the mechanisms by which serotonergic stimulants induce nausea and vomiting are not fully understood.
• Drugs and Toxins: The exact molecular and neuronal mechanisms of drugs and toxins, including anesthetics and opioid compounds, that can cause nausea and vomiting are not fully understood. But it is said that they can communicate with the nausea center by stimulating the postrema area at the base of the fourth ventricle through the release of dopamine and serotonin and cause nausea and vomiting.