Management of Postoperative Nausea and Vomiting - A Consensus Guideline

Introduction-

Emergence from the theater room post-surgery and general anesthesia is accompanied by some physiologic disturbances like postoperative nausea and vomiting (PONV), hypothermia (a sudden drop in body temperature), shivering, hypoxia (insufficient oxygen levels), and cardiovascular instability. The PONV complication rate in a PACU (post-anesthesia care unit) is 24 percent, according to a prospective study.

What Is PACU?

The post-anesthesia care unit is a setup designed and staffed to monitor the patients who are recovering from surgery and to care for the patients who are facing the immediate physiological effects of anesthesia. There will be one-on-one monitoring inside the operating room along with facilities to resuscitate patients who get unstable. It has a calm and tranquil environment to facilitate patients’ recovery and enhance their comfort.

What Is PONV?

After surgery and due to the induction of general anesthesia, the patients undergo various physiologic disturbances affecting multiple organs. The most common effect is postoperative nausea and vomiting (PONV). Prophylactic medications should be given to the patient to prevent PONV in all patients. Without this prophylaxis, about 75 percent or one-third of the patients who undergo inhalational anesthesia are likely to develop PONV.

How Does PONV Affect the Patient?

• It will cause significant discomfort in the patient.

• PONV can result in unanticipated hospital admission post-surgery.

• Due to PONV, there can be a delay in the discharge of the patient from PACU.

• There is an increased chance of pulmonary aspiration in the patient. Pulmonary aspiration refers to the accidental inhalation of vomit or saliva into the airways.

• From the patient’s perspective, the patient will find PONV more uncomfortable than postoperative pain.

How to Prevent PONV?

Prophylactic measures like modification of the technique for anesthesia administration and pharmacologic intervention should be done to reduce the incidence of PONV. Pharmacologic intervention includes Droperidol 1.25 milligrams, Dexamethasone four milligrams, or Ondansetron four milligrams. Anesthesia technique-related modification should be implicated by the inclusion of Propofol instead of volatile anesthetics, nitrogen instead of nitrous oxide, and Remifentanil instead of Fentanyl. According to a study, the use of antiemetics reduced the incidence of PONV to 26 percent. Propofol (19 percent decrease) and nitrogen (12 percent decrease) together reduced PONV to the same degree.

A) Prophylaxis:

Specific antiemetics such as Scopolamine, Aprepitant, and Dexamethasone should not be re-dosed at all. The goal is to give at least two different antiemetics to every patient older than 18 years of age who is undergoing any surgical procedure under inhalational general anesthesia if they have at least three risk factors of PONV. Emend (Aprepitant) can be very effective in very high-risk patients and refractory cases. The recommended dose for the drug is 40 milligrams by mouth within three hours before the administration of anesthesia. This drug has been shown to be effective at least 48 hours after surgery.

Commonly Used Antiemetics (Adult Doses):

B) Reduction of Baseline Risks:

The following can be done to reduce the incidence of PONV:

• Try to use regional anesthesia as far as possible instead of general anesthesia.

• Avoid using volatile anesthetic agents.

• Prefer to use Propofol infusion.

• Minimize the use of perioperative opioids. If possible, use NSAIDs (non-steroidal anti-inflammatory drugs).

• Keep the patient adequately hydrated.

What Are the Risk Factors for PONV?

1. Female gender, especially postpubertal girls, have a higher incidence of developing PONV.

2. Patients who do not smoke have increased chances of PONV.

3. Patients who have a history of PONV also are at risk.

4. Patients with conditions like motion sickness are also at risk of developing post-operative nausea and vomiting.

5. The need for postoperative opioids than intraoperative opioids is also an independent risk factor.

6. If the surgery extends beyond 30 minutes, then post-operative nausea or vomiting can occur.

7. If it is a high-risk surgery, like adenotonsillectomy and strabismus surgery, then PONV can occur.

8. It has a predilection to occur in patients above three years of age and less than 50 years of age.

9. Gynecologic and laparoscopic surgeries, along with cholecystectomy, have increased the incidence of PONV.

How to Manage PONV?

Even after prophylactic measures, a subset of patients have PONV, and there is a need to manage them in the PACU. If a dose of antiemetic did not prevent PONV incidence, then a higher dose of the same drug is not advisable to be administered for managing PONV within six hours of the first dose.

In a patient with established PONV, repetitive assessment of the patient and prompt treatment should be started. The following have to be checked during the assessment of the patient:

• Presence of blood in the throat.

• Hypotension.

• PCA (patient-controlled analgesia) opioids.

• Hypovolemia.

• Abdominal obstruction.

• Temperature checks like hypothermia, if any.

• Sepsis.

The patients should be administered with Ondansetron four milligrams as the first line of treatment. But this can be done only if the patient has not received the same drug before six hours. If not, consider an antiemetic like Prochlorperazine 12.5 milligram intramuscular injection. This drug is contraindicated in patients with Parkinson’s disease. Other options include a lower dosage of Propofol boluses of about 20 milligrams, but this is also having a risk of airway compromise. Cyclizine can be given parenterally if Prochlorperazine and Ondansetron are not appropriate for the patient. In elderly patients, the dose of Cyclizine and Prochlorperazine should be reduced.

General management includes minimizing the movement of patients, ensuring adequate analgesia is given to the patient for pain relief, ensuring adequate oxygen levels and normal blood pressure, and intravenous fluids in patients who are dehydrated.

Conclusion:

Postoperative nausea and vomiting are frequent complications after anesthesia and surgery. However, appropriate prophylaxis on account of the risk factors present in the patient can greatly reduce the incidence of PONV. All patients should be given antiemetics when they are shifted to the normal ward. Management of PONV in the PACU requires careful monitoring and swift intervention.