Author:
Kai Knudsen
Granskare:
Magnus SnäckestrandUpdated:
27 August, 2025
This chapter describes how to prevent nausea and the various medications that can be administered to counteract nausea associated with anesthesia and surgery.
Postoperative Nausea – PONV
Postoperative nausea and vomiting (PONV) has long been a significant problem in anesthesia and intensive care. In fact, this issue is what most concerns many patients before their upcoming anesthesia. During the preoperative conversation, it is often the fear of postoperative nausea that the patient first brings up. It has been shown that the choice of anesthesia technique is important for the occurrence of PONV, as well as the presence of various risk factors and the type of surgery involved. PONV can be somewhat prevented by administering one or more antiemetics perioperatively. Inhalation anesthesia results in significantly more PONV compared to intravenous anesthesia; however, there is no significant difference between desflurane and sevoflurane. The incidence of PONV is around 10-20%, in some groups up to 40%. The use of nitrous oxide increases the risk of nausea. Blood pressure drops, bradycardia, and hypoxia can trigger nausea and vomiting, as can prolonged fasting or constipation. The type of surgery naturally also plays a role. High risk of PONV is associated with abdominal surgery and breast surgery. Diabetes causes delayed gastrointestinal motility. A high dose of neostigmine for reversal of muscle relaxants increases the risk of PONV.
As preventive treatment, dopamine receptor blockers (droperidol, metoclopramide) or 5-HT3 blockers (ondansetron, granisetron) are usually used. The commonly used medications are Zofran (ondansetron), Kytril (granisetron), Betapred (betamethasone), Primperan (metoclopramide), or Dridol (droperidol). Granisetron is significantly longer-acting compared to ondansetron. A combination of 5-HT3 blockers plus betamethasone or Dridol has better efficacy than a single drug alone. The combination of 5-HT3 blockers with Dridol provides approximately the same positive effect as a combination with betamethasone. A probably better alternative to betamethasone is dexamethasone, where the scientific evidence for prophylactic effect against nausea is greater.
Suggestions for Prophylaxis Against PONV
- Low risk of PONV: ondansetron alone.
- Moderate risk of PONV: ondansetron plus betamethasone/dexamethasone.
- High risk of PONV: ondansetron, droperidol plus betamethasone/dexamethasone.
Transient ECG changes, including QT interval prolongation, have been reported in rare cases with 5-HT3 blockers. Caution should be exercised in patients with prolonged QT syndrome or arrhythmias.
Risk Factors for PONV
- Young patient
- Female gender
- Anxious patient
- Prone to motion sickness
- Non-smoker
- Previous nausea during anesthesia
- Constipation or other gastrointestinal issues
- Prolonged fasting
- Postoperative use of opioids
- Gallbladder disease
Ondansetron (Ondansetron/Zofran®)
Ondansetron: Serotonin antagonist, antiemetic.
Dosage: 4-8 mg IV as prophylaxis (8 mg is the most effective dose), 2 mg/ml solution = 2-4 ml.
Standard dose: 4 mg x 2 IV for PONV.
Warning: Not for children under 2 years old. Previous reactions to selective serotonin antagonists. Should not be used during the first trimester of pregnancy.
Atropine (Atropine®)
Anticholinergic.
Dosage: 0.5 mg IV as prophylaxis = 1 ml. 0.5 mg/ml solution. Counteracts bradycardia and nausea secondary to gastric retention and vomiting. Can be repeated up to a maximum of 1 mg per treatment session.
Standard dose: 0.5 mg x 1 IV for PONV and bradycardia episodes.
Warning: Caution in tachycardia, cardiac ischemia, hyperthermia, urinary retention, accommodation difficulties, confusion.
Betamethasone (Betapred®)
Water-soluble glucocorticoid, antiemetic. Lacks mineralocorticoid effect.
Dosage: 4 mg IV as prophylaxis, 4 mg/ml solution = 1 ml.
Standard dose: 4 mg x 1 IV for PONV.
Warning: Caution in osteoporosis, vertebral compression fractures, newly created intestinal anastomoses, psychosis, mania, gastric ulcers, tuberculosis, diabetes (increases blood sugar), hyperglycemia, hypertension, heart failure.
Dexamethasone (Dexamethasone®)
A synthetic corticosteroid with mainly glucocorticoid effect, antiemetic.
Dosage: 8-16 mg PO as treatment.
Standard dose: 8 mg x 1 PO for PONV.
Warning: Caution in osteoporosis, vertebral compression fractures, newly created intestinal anastomoses, psychosis, mania, gastric ulcers, tuberculosis, diabetes (increases blood sugar), hyperglycemia, hypertension, heart failure.
Droperidol (Dridol®)
Dopamine antagonist, neuroleptic, antiemetic. Vasodilator.
Dosage: 0.5-2.5 mg (most effective dose 1 mg), 0.2-1 ml, 2.5 mg/ml solution.
Standard dose: 0.4 ml, 1 mg. ECG monitoring 2-3 hours after injection.
Side effects: Nightmares, stiffness, rigidity, dystonias.
Warning: QT prolongation, pheochromocytoma.
Granisetron (Kytril®)
Antiemetic, serotonin antagonist.
Dosage: 3 mg IV as prophylaxis, 1 mg/ml solution = 3 ml. An additional dose may be given per day. Max 6 mg per day.
Standard dose: 3 mg (3 ml) given slowly intravenously for PONV.
Warning: Subileus. Severely impaired liver function. Previous reactions to selective serotonin antagonists.
Metoclopramide (Primperan®)
Antiemetic, dopamine receptor blocker. Metoclopramide has a centrally acting antiemetic effect and a prokinetic effect on the gastrointestinal tract.
Dosage: 5-10 mg IV as prophylaxis, 5 mg/ml solution = 1-2 ml. An additional dose may be given per day. Max 10 mg per day. 0.15 mg/kg for children.
Standard dose: 5 mg (1 ml) given slowly intravenously for PONV.
Note: Extrapyramidal side effects may occur, including stiffness and rigidity. Should not be given in known epilepsy as it lowers the seizure threshold.
Oxygen
Oxygen can counteract nausea secondary to hypoxia.
Dosage: Given via nasal cannula 2 l/min or via breathing mask 5 l/min.
Standard dose: 2 l/min in nasal cannula for PONV.
Warning: Caution in respiratory insufficiency (advanced COPD) and hypoventilation.
The time a gas bottle with oxygen ("bomb") is enough at different flows and pressures
| Gas cylinder size | Pressure (bar) | 2 l/min | 3 l/min | 5 l/min | 10 l/min |
|---|---|---|---|---|---|
| 1 liter | 200 | 1 hour 40 min | 1 hour | 30 min | 20 min |
| 150 | 1 hour 15 min | 50 min | 30 min | 15 min | |
| 100 | 50 min | 33 min | 20 min | 10 min | |
| 50 | 25 min | 17 min | 10 min | 5 min | |
| 2,5 liter | 200 | 4 hour 10 min | 2 tim 45 min | 1 tim 40 min | 50 min |
| 150 | 3 hour | 2 hour | 1 tim 15 min | 38 min | |
| 100 | 2 hour | 1 hour 20 min | 50 min | 25 min | |
| 50 | 1 hour | 50 min | 25 min | 13 min | |
| 5 liter | 200 | 8 hours 20 min | 5 hours 30 min | 3 hours 20 min | 1 hour 40 min |
| 150 | 6 hours 15 min | 4 hours 10 min | 2 hours 30 min | 1 hour 15 min | |
| 100 | 4 hours 20 min | 2 hours 45 min | 1 hour 40 min | 38 min | |
| 50 | 2 hours | 1 hour 20 min | 50 min | 25 min |
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