Postoperative Nausea and Vomiting (PONV)

Stratify with a validated score - the Apfel score is the standard adult tool: female sex, nonsmoker, history of PONV or motion sickness, and planned postoperative opioids. Koivuranta is the alternative adult score; POVOC is the pediatric one, weighting age over 3 years, strabismus surgery, duration over 30 minutes, and family history of PONV or motion sickness. Four risk factors puts the chance of PONV near 80%.

Match prophylaxis to the score, both ways - agent count scales with risk, and some algorithms give four agents to the four-risk-factor patient. Overtreating the low-risk patient buys cost and side effects with no benefit, which is the failure mode most departments actually have.

Know the high-risk procedures - ocular, tympanic, intracranial, abdominal, gynecologic, and urologic surgery all carry elevated rates. Extremes of age are protective, and smoking lowers the risk.

First-line agents - ondansetron (5-HT3), low-dose dexamethasone, droperidol (antidopaminergic), transdermal scopolamine, and metoclopramide. Combinations across classes beat single agents. Scopolamine has to go on preoperatively to be working when you need it; metoclopramide also raises lower esophageal sphincter tone and speeds gastric emptying, so it does double duty in the aspiration-risk patient.

Aprepitant for the high-stakes case - 40 mg PO within three hours of induction. Cost keeps it for genuinely high-risk patients or where the act of vomiting would wreck the surgical repair.

Technique - propofol TIVA sidesteps the volatile agents and nitrous oxide that drive PONV, and propofol has mild antiemetic properties at low dose. But propofol infusion, whether full TIVA or combined with a volatile, does not reduce PONV in cases under two hours — do not reach for it reflexively in a short case.

Cut the opioid load - every perioperative opioid raises the risk. Multimodal analgesia with regional and epidural techniques, NSAIDs, acetaminophen, and dexmedetomidine reduces the exposure. Gabapentin, alone and particularly combined with dexamethasone, reduced PONV after knee and hip arthroplasty done under neuraxial anesthesia.

Oxygen and hydration - supplemental oxygen and IV hydration reduce incidence or severity. They cost nothing and they belong in the plan for anyone scoring moderate or above.

Side effects that should change your pick - 5-HT3 antagonists cause headache and slightly prolong QT; droperidol prolongs QT more and worsens Parkinson disease; antihistamines and anticholinergics sedate and confuse, so go carefully in the elderly; dexamethasone raises glucose and some surgeons ask you to skip it over wound-healing concerns; aprepitant renders oral contraceptives ineffective, which the patient needs to be told.

Rule out the mimics before treating - cardiac ischemia, hypotension, hypoxia, ileus, and metabolic derangement all present as postoperative nausea. Unexpected or severe PONV gets a focused history, exam, and an electrolyte panel if vomiting has been extensive, not just another dose of ondansetron.

Rescue in PACU - promethazine is the common rescue agent, but it sedates and lengthens PACU stay. Restrict movement, remove noxious stimuli, and give oxygen alongside the drug.

Nonpharmacologic adjuncts - P6 acupoint stimulation on the palmar wrist (acupressure, acupuncture, TENS, laser, capsicum plaster) has documented success across multiple studies. Isopropyl alcohol swabs to the nose have mixed results.

Neuraxial nausea is its own thing - nausea is a common complication of neuraxial anesthesia and its mechanism is not understood. Do not assume the same prophylaxis logic transfers from general anesthesia.

Postoperative nausea and vomiting (PONV) is nausea, retching, or vomiting in the hours after anesthesia — up to 30% of the general surgical population and up to 80% of high-risk patients. The chemoreceptor trigger zone in the medulla is the final common path, with acetylcholine, dopamine, and substance P among the transmitters involved, which is why the antiemetic classes span serotonin, dopamine, histamine, acetylcholine, and neurokinin-1 receptors — no single agent covers it.

Input arrives from several directions: the GI tract, where opioids act directly; the vestibular system, through movement and through sensitization by anesthetic agents; and the brainstem itself.

It is not just a comfort issue. The Valsalva of active vomiting raises intrathoracic and intracranial pressure and can produce bradycardia, while the episode itself drives a sympathetic surge with hypertension and tachycardia — a real problem after intracranial, ophthalmic, or tympanic surgery and in anyone intolerant of a pressure swing.