Causes of Prolonged Nausea After Surgery

Introduction

Any nausea and vomiting occurring in the first 24 to 48 hours of surgery are called postoperative nausea and vomiting. It is one of the common problems occurring in anesthesia practice. Post-operative nausea and vomiting are triggered by factors related to the surgery, patient, and anesthesia. The risk of nausea and vomiting can be evaluated with the help of a scoring system like the Apfel scoring system. Based on the scoring system, prophylaxis can be administered to the patients. Several new drugs are used for the prophylaxis of postoperative nausea and vomiting. A combination of pharmacological and non-pharmacological prophylaxis can be used for patients with a high risk of developing nausea and vomiting.

What Is Nausea?

Nausea is an unpleasant feeling in the stomach that leads to an urge to vomit but does not always cause vomiting.

What Is Vomiting?

Vomiting is the voluntary or involuntary emptying of the stomach's contents through the mouth.

What Is the Pathophysiology of Postoperative Nausea and Vomiting?

The pathophysiology of postoperative nausea and vomiting is complex and not understood completely. The structures in the brain associated with nausea and vomiting are found in the medulla oblongata, also known as the brain stem. These structures include the chemoreceptor trigger zone at the end of the fourth ventricle and the nucleus tractus solitarius (a part of the brain stem). The chemoreceptor trigger zone receives the signal from the vagal afferents in the gastrointestinal tract and also detects certain toxins and drugs in the bloodstream and cerebrospinal fluid because of the lack of a blood-brain barrier. The nucleus tractus solitarius triggers vomiting by stimulating the nucleus ambiguous, the ventral respiratory group, and the motor nucleus of the vagus nerve.

Postoperative nausea and vomiting can also be triggered by factors like anesthetics, anxiety, stress, opioids, certain drugs, and movement. Several neurotransmitter pathways are involved in stimulating vomiting.

They are as follows:

• The vagal pathway in the gastrointestinal system.

• The chemoreceptor trigger zone.

• Neuronal pathways from the vestibular system.

• Midbrain afferents.

• Reflex afferent pathways from the cerebral cortex.

The enterochromaffin cells in the gastrointestinal tract secrete serotonin, and the vagus nerve interacts with the chemoreceptor trigger zone via the 5-HT3 receptors. The chemoreceptor trigger zone, in turn, communicates with the nucleus tractus solitarius through the dopamine-2 receptors. The alterations in the equilibrium are detected by the vestibular system, which interacts with the nucleus tractus solitarius via acetylcholine and histamine. The process of nausea and vomiting due to anxiety occurs in the cerebral cortex, which directly communicates with the nucleus tractus solitarius through various neuroreceptors.

What Are the Factors Leading To Postoperative Nausea and Vomiting?

Nausea and vomiting are caused by the following factors:

1. Patient-related Factors:

• Gender - Compared to men, women are more prone to experience postoperative nausea and vomiting.

• Smoking - People who do not smoke are more prone to experience postoperative nausea and vomiting than smokers.

• Motion Sickness - Individuals with a tendency of motion sickness or vomiting in the previous surgery are at an increased risk.

• Age - Individuals under fifty years are at an increased risk of developing nausea and vomiting post-surgery.

• Other Factors - Individuals with diabetes mellitus, hypothyroidism, pregnancy, increased intracranial tension, etc., are at an increased risk of postoperative nausea and vomiting.

2. Preoperative Factors:

Preoperative includes the following:

• Preoperative Fasting.

• Anxiety.

3. Intraoperative Factors:

• Type of Surgery - Surgeries like cholecystectomy, laparoscopic, and gynecological surgeries are related to an increased incidence of postoperative nausea and vomiting.

• Time of Surgery - Surgeries that take a long time are usually associated with postoperative nausea and vomiting.

• Anesthesia with Nitrous oxide used in laparoscopic surgeries is found to cause postoperative nausea and vomiting due to these phenomenons:

1. Nitrous oxide stimulates the sympathetic nervous system with the release of catecholamine.

2. The alterations in the middle ear pressure stimulate the vestibular system.

3. The exchange of nitrous oxide and nitrogen in the gas filled in the gastrointestinal tract leads to increased abdominal distension.

4. Agents like cyclopropane and ether can cause an increase in postoperative nausea and vomiting.

5. Postoperative nausea and vomiting can also be induced by anesthetic agents like Etomidate and Ketamine.

6. The nitrous oxide-opioid-relaxant is found to be associated with an increased incidence of postoperative vomiting by directly stimulating the chemoreceptor trigger zone.

7. Opioids can also cause nausea and vomiting by the stimulation of the opioid receptors present in the chemoreceptor trigger zone.

The risk of developing postoperative nausea and vomiting is much less in patients receiving local anesthesia than in general anesthesia patients. The risk of nausea is greater in procedures with central block than procedures with peripheral block as this leads to postural hypotension inducing nausea and vomiting.

4. Postoperative Factors:

The postoperative factors include the following:

• Pain in the abdomen or pelvic area is a common cause of postoperative nausea.

• A sudden change in position, motion, or shift to ward from the anesthetic recovery ward to the post-surgical ward can also lead to nausea and vomiting in individuals administered with opioid compounds.

How To Prevent Postoperative Nausea and Vomiting?

Postoperative nausea and vomiting can be prevented by the following measures:

1. Reducing the Baseline Risk:

• The patient's baseline risk should be calculated with the help of the Apfel risk score.

• Local anesthesia should be used in place of general anesthesia wherever possible.

• General anesthesia should be carried out with intravenous Propofol and nitrogen which decreases the incidence of nausea and vomiting by 30 percent.

• The use of opioids should also be restricted to reduce the risk of developing nausea and vomiting.

2. Combination of Antiemetics:

Antiemetic medications such as Ondansetron, Dexamethasone, and Droperidol reduce the risk of vomiting by 25 percent. People with low-to-moderate risk can be administered one or two interventions, and patients with high risk can receive three to four interventions. It is essential to consider the patient's risk and the interventions' safety.

3. Patient Treatment:

Many patients still suffer from postoperative nausea and vomiting despite the available guidelines. In such cases, Ondansetron is generally used as an antiemetic drug. Antiemetics should be of a different class compared to the drug used as prophylaxis.

Conclusion

Postoperative nausea and vomiting are unpleasant episodes. The vomiting center in the medulla gets affected by anesthetic drugs, opioids, and surgery. The management of postoperative nausea and vomiting is done by treating the different causes of nausea and vomiting. Established nausea and vomiting can be treated with the help of rescue medication or certain drugs that have not been used as a prophylactic treatment. Purchasing disposable vomit bags can help to prevent mess. High-risk individuals can also benefit from prophylactic antiemetic drug administration.