By Kai Knudsen, Senior Physician in Anesthesia & Intensive Care. Sahlgrenska University Hospital.
Postoperative nausea and vomiting (PONV) has long been a significant problem in anesthesia and intensive care. In fact, this problem is the most worrying of many patients for their imminent anesthesia. In the preoperative interview, there is often concern about postoperative nausea that the patient first addresses. It has been shown that the choice of anesthesia technique is important for the emergence of PONV as well as the presence of a variety of risk factors as well as the type of surgery that is relevant. PONV can be prevented to some extent by administering one or more antiemetics peroperatively. Inhalation anesthesia produces significantly more PONV compared to intravenous anesthesia, however, no significant difference between desfluran and sevoflurane has been demonstrated. The incidence of PONV is around 10-20%, in some groups up to 40%. The use of nitrous oxide gives an increased risk of nausea. Blood pressure drops, bradycardia and hypoxia can trigger nausea and vomiting as well as prolonged permanent or constipation. Of course, the type of surgery also plays a part. High risk of PONV is present in abdominal surgery and chest surgery. Diabetes causes prolonged may bowel motility. High doses of neostigmine for reversal of muscle relaxants causes increased risk of PONV.
As a preventive treatment, dopamine receptor blockers (droperidol, metoclopramide) or 5-HT3 blockers (ondansetron, granisetron) are usually used. The commonly used drugs are ondansetron (Zofran), granisetron (Kytril), betamethasone (Betapred), dexamethason, metoclopramide (Primperan) or droperidol (Dridol). Granisetron is significantly more long-acting compared to ondansetron. A combination of 5-HT3 blockers plus betamethasone or dridol has a better effect than just one drug. The combination of 5-HT3 blockers with dridol gives approximately the same positive effect as a combination with betamethasone. A probably better alternative to betametason is dexametason where the scientific evidence of prophylactic effect against nausea is greater.
Proposals for prophylaxis against PONV:
- Small risk for PONV: ondansetron only.
- Moderate risk of PONV: ondansetron plus betamethasone.
- High risk of PONV: ondansetron, droperidol plus betamethasone.
Transient ECG changes, including prolongation of QT interval have been reported rarely with 5-HT3 blockers. Caution should be exercised in patients with prolonged QT syndrome or arrhythmias.
Risk factors for PONV are:
- Young patient
- Female gender
- Anxious patient
- Easy to get sick or sick
- Earlier nausea in anesthesia
- Constipation or other stomach upsets
- Long-term fasting
- Use of opioids postoperatively
- Gall bladder disease
Dosage: 0.5 mg i v as prophylaxis = 1 ml. 0.5 mg/ml solution, prevents bradycardia and nausea secondary to ventricular retention and vomiting. Repeat to max 1 mg per treatment.
Standard dose: 0.5 mg x 1 i v at PONV and bradycardia episodes.
Cave: Caution in Tachycardia, Cardiac Disease, Hyperthermia, Urinary Retention, Accommodation Difficulty, Confusion.
Water-soluble glucocorticoid, antiemetic drug.
Dosage: 4 mg i v as prophylaxis, 4 mg/ml solution = 1 ml.
Standard dose: 4 mg x 1 i v at PONV.
Cave: Caution in osteoporosis, cot compressions, newborn bowel ducts, psychosis, fashion, ulcer ventriculi, tbc, diabetes (raises blood sugar), hyperglycemia, hypertension, cardiac insufficiency.
Dopamine antagonist, neuroleptic drug, antiemetic.
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, dystonia.
Contraindications: QT extension, Phaeochromocytoma
Antiemetic drug, a serotonin antagonist.
Dosage: 3 mg is given as prophylaxis, 1 mg/ml solution = 3 ml. An additional dose can be given per day. Maximum dose 6 mg per day.
Standard dose: 3 mg (3 ml) is given intravenously at PONV.
Contraindications: Subileus. Severe liver failure. Previous reactions to selective serotonin antagonists.
Antiemetic drug, dopamine receptor blocker.
Metoclopramide has a centrally acting antiemetic effect and a motility promoting effect within the gastrointestinal tract.
Dosage: 5-10 mg is given as prophylaxis, 5 mg/ml solution = 1-2 ml. An additional dose can be given per day. Max 10 mg per day. 0.15 mg/kg for children.
Standard dose: 5 mg (1 ml) is given intravenously intravenously at PONV.
Caution: Extrapyramidal side effects may occur with stiffness and rigidity. Should not be given to patients with EP as it lowers the seizure threshold.
Nausea secondary to hypoxia.
Dosage: In nasal cavities 2 l/min or in respiratory system 5 l/min.
Standard dose: 2 l/min in nose catheters at PONV.
Caution: Caution in respiratory insufficiency (advanced COPD) and hypoventilation.
|Size of each bottle||Pressure (bar)||2 l/min||3 l/min||5 l/min||10 l/min|
|1 litre||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 litres||200||4 hours 10 min||2 hours 45 min||1 hour 40 min||50 min|
|150||3 hours||2 hours||1 hour 15 min||38 min|
|100||2 hours||1 hour 20 min||50 min||25 min|
|50||1 hour||50 min||25 min||13 min|
|5 litres||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 hours 40 min||38 min|
|50||2 hours||1 hour 20 min||50 min||25 min|
Serotonin antagonist, antiemetic drug.
Dosage: 4-8 mg iv as prophylaxis (8 mg most effective dose), 2 mg/ml solution = 2-4 ml.
Standard dose: 4 mg x 2 i v at PONV.
Caution: Not for children under 2 years. Previous reactions to selective serotonin antagonists.