Overview
Definition:
Postoperative nausea and vomiting (PONV) is a common and distressing complication following anesthesia and surgery
It is characterized by the subjective sensation of nausea and/or the involuntary expulsion of gastric contents
PONV can significantly impact patient satisfaction, prolong hospital stay, and increase healthcare costs.
Epidemiology:
The incidence of PONV varies widely depending on patient risk factors, type of surgery, and anesthetic technique, ranging from 20% to as high as 80%
Higher risk is associated with female gender, history of PONV or motion sickness, nonsmoking status, and use of volatile anesthetics
Certain surgical procedures, such as gynecological, abdominal, and intra-ocular surgeries, are associated with higher PONV rates.
Clinical Significance:
PONV can lead to serious complications including dehydration, electrolyte imbalance, aspiration, wound dehiscence, and esophageal rupture
It also causes significant patient discomfort, anxiety, and dissatisfaction with surgical care
Effective prevention and management are crucial for improving patient outcomes and enhancing the overall surgical experience
Understanding risk stratification and evidence-based prophylaxis is essential for all surgical residents.
Risk Factors
Patient Factors:
Female gender
History of PONV or motion sickness
Nonsmoking status
Age (higher in younger adults)
Obesity
Opioid use (preoperative and postoperative).
Anesthetic Factors:
Use of volatile anesthetic agents
Nitrous oxide
Opioid administration (intravenous, intraoperative)
Duration of anesthesia
Type of anesthesia (general anesthesia carries higher risk than regional anesthesia).
Surgical Factors:
Type of surgery (e.g., laparoscopic procedures, gynecological, abdominal, ear/nose/throat, breast surgery)
Duration of surgery
Increased intra-abdominal pressure
Stimulation of visceral afferents.
Risk Scoring Systems:
Apfel score is widely used to stratify risk: female gender (+1), history of PONV or motion sickness (+1), nonsmoking (+1), and intraoperative use of opioids (+1)
Patients with 0-1 risk factors have low risk
2 risk factors moderate risk
3-4 risk factors high risk.
Prevention Strategies
Multimodal Prophylaxis:
Combining multiple antiemetic agents from different pharmacological classes targeting various receptors is more effective than monotherapy
Aim for prophylaxis in patients with a risk score of 2 or higher.
Pharmacological Prophylaxis:
Serotonin (5-HT3) receptor antagonists (e.g., ondansetron, granisetron, palonosetron) are first-line agents, often given intraoperatively
Dexamethasone, a corticosteroid, is also effective, especially when given intraoperatively
Dopamine antagonists (e.g., droperidol, prochlorperazine) and antihistamines (e.g., dimenhydrinate) can be used, though some have more sedative side effects
Butyrophenones like droperidol are highly effective but may be associated with QT prolongation.
Non Pharmacological Prophylaxis:
Adequate hydration
Avoidance of nitrous oxide where possible
Limiting intraoperative opioid use
Early mobilization postoperatively
Acupressure bands (e.g., P6 acupoint stimulation) may offer some benefit
Ensuring adequate ventilation to minimize volatile anesthetic exposure.
Management Of Established PONV
Acute Management:
If PONV occurs despite prophylaxis, administer an antiemetic from a different class than those used for prophylaxis
Options include IV ondansetron, IV droperidol, or IV metoclopramide
Consider adjusting opioid analgesia if it is contributing.
Pharmacological Options:
For breakthrough PONV: Ondansetron 4 mg IV
Dexamethasone 4-8 mg IV if not given prophylactically
Prochlorperazine 10-25 mg IV or IM
Promethazine 12.5-25 mg IV or IM (caution with side effects)
Haloperidol 0.5-1 mg IV (for refractory PONV)
Scopolamine transdermal patch (apply preoperatively).
Supportive Care:
Maintain adequate hydration with IV fluids
Monitor vital signs and fluid balance
Advance diet as tolerated
Avoid triggers like strong odors
Encourage deep breathing and relaxation techniques.
Specific Surgical Considerations
Laparoscopic Surgery:
Higher incidence of PONV due to pneumoperitoneum and CO2 absorption
Multimodal prophylaxis is strongly recommended
Consider avoidance of nitrous oxide.
Intraocular Surgery:
High risk of PONV, particularly associated with remifentanil infusion and patient susceptibility
Ondansetron and dexamethasone are frequently used
Careful management of anesthetic agents is critical.
Bariatric Surgery:
Increased risk due to prolonged surgery, opioid use, and altered gastrointestinal physiology
Aggressive multimodal prophylaxis is essential.
Gynecological And Abdominal Surgery:
These procedures often involve manipulation of abdominal organs, increasing PONV risk
Antiemetic choice should consider potential interactions and patient factors.
Key Points
Exam Focus:
The Apfel score is crucial for risk stratification
Multimodal prophylaxis is superior to monotherapy
Different classes of antiemetics target different receptors (5-HT3, D2, H1, NK1)
Palonosetron has a longer duration of action and higher efficacy for established PONV
Dexamethasone has antiemetic properties and also reduces postoperative pain.
Clinical Pearls:
Always tailor prophylaxis to individual patient risk factors and surgical procedure
Consider the timing of antiemetic administration for optimal efficacy
Be aware of the side effect profiles of different antiemetic classes, especially sedation and QT prolongation
For patients with a history of PONV, consider adding a third agent for prophylaxis.
Common Mistakes:
Underestimating patient risk factors
Relying on a single antiemetic for high-risk patients
Delaying prophylaxis until nausea or vomiting has already occurred
Not considering alternative antiemetic classes for breakthrough PONV
Overlooking the potential for drug interactions or contraindications.