What is Postoperative Nausea and Vomiting (PONV)?
Postoperative nausea and vomiting (PONV) is the feeling of sickness and urge to vomit that occurs after a surgical procedure requiring anesthesia. While it is one of the most undesirable aspects of surgery for many patients, anesthesiologists have developed numerous strategies to predict, prevent, and treat it. PONV is a multifactorial issue, meaning it isn't caused by a single thing but by a combination of a patient's individual risk, the anesthetic drugs used, and the type of surgery performed.
The Pharmacological and Physiological Causes of Nausea
From a pharmacological perspective, several factors contribute to the emetic (vomiting) reflex. Anesthetic drugs, particularly the volatile or inhaled anesthetic gases, are a significant contributor. These agents can activate neural pathways in the brain that trigger nausea and vomiting. The severity can correlate with the duration of exposure to these agents.
Furthermore, pain-relief medications, especially opioids like morphine and fentanyl, are a known cause of nausea and vomiting. Opioids can slow down the gastrointestinal system and directly affect brain centers that regulate nausea. The amount and timing of opioid use are carefully managed by anesthesiologists to balance pain control with the risk of PONV.
Physiologically, other elements also play a role. Dehydration, which can result from the required fasting before surgery and fluid loss during the procedure, is a major contributor to nausea. Changes in blood pressure, a common occurrence during and after surgery, can also cause feelings of nausea and dizziness. Surgical manipulation of certain organs, especially in the abdomen, can disrupt normal gastrointestinal function and lead to feelings of sickness.
Key Risk Factors for Developing PONV
Certain patient-related and surgery-related factors can increase the likelihood of developing PONV. Anesthesiologists use a scoring system to assess a patient's risk and determine the appropriate level of prophylactic (preventive) care. These factors include:
- Gender: Women are at a higher risk of developing PONV, for reasons that are not entirely clear but may be linked to hormonal fluctuations.
- History of Motion Sickness or Prior PONV: Patients who have a history of motion sickness or have experienced PONV in a previous surgery are significantly more likely to experience it again.
- Non-Smoker Status: For unknown reasons, non-smokers have a higher incidence of PONV than smokers.
- Type of Anesthesia: As discussed, general anesthesia carries a higher risk than local or regional techniques. The use of volatile anesthetics and opioids also elevates risk.
- Duration and Type of Surgery: Longer surgical procedures are associated with a greater risk of PONV. Procedures involving the abdomen, ear, gynecological system, and laparoscopic techniques are also known to carry a higher risk.
Strategies for Prevention and Management
Modern anesthesiology employs a multi-pronged approach to prevent and manage PONV. The strategy is often based on a patient's individual risk profile.
- Medication Selection: Anesthesiologists can choose anesthetic techniques that are less likely to cause nausea, such as total intravenous anesthesia (TIVA) using propofol, which has anti-emetic properties.
- Prophylactic Antiemetics: For patients with one or more risk factors, medication is administered to prevent nausea before it starts. Common options include ondansetron (a 5-HT3 receptor antagonist), dexamethasone (a corticosteroid), and aprepitant (an NK1 receptor antagonist). These medications target different neural pathways involved in the emetic reflex.
- Multimodal Approach: Combining antiemetics from different drug classes can have an additive effect in reducing PONV, especially in high-risk patients.
- Hydration and Diet: Adequate hydration is maintained with intravenous fluids. After surgery, patients are typically advised to start with clear liquids and bland foods and to reintroduce their normal diet slowly to avoid upsetting the stomach.
- Pain Management: Careful management of pain with reduced reliance on opioids can help minimize nausea. The anesthesiologist may utilize regional nerve blocks or other non-opioid pain-relieving options.
What to Expect During Recovery
After anesthesia, patients are moved to a post-anesthesia care unit (PACU) where they are closely monitored as the effects of the anesthetic wear off. Some common side effects during this period include drowsiness, grogginess, and sometimes nausea or chills. If nausea or vomiting occurs, nurses and anesthesiologists can provide additional rescue antiemetic medication. Recovery typically involves a gradual return to normal consciousness, mobility, and oral intake. Patients are advised to arrange for a ride home and have someone assist them for the first 24 hours after a procedure involving general anesthesia.
Comparison of Anesthesia Types and Risk of Sickness
| Anesthesia Type | Key Characteristics | Risk of Postoperative Sickness | Prevention and Treatment Strategies |
|---|---|---|---|
| General Anesthesia | Induces full unconsciousness and affects the entire body. Often involves placing a breathing tube. | Highest risk of PONV due to systemic effects of anesthetic agents and associated opioid use. | Risk assessment, prophylactic multi-drug antiemetic therapy, use of less emetogenic agents like propofol (TIVA). |
| Regional Anesthesia | Numbs a specific, large region of the body (e.g., epidural for C-section, nerve block for arm surgery). | Lower risk of systemic side effects like nausea compared to general anesthesia, but still possible, especially with opioid use. | Fewer interventions needed. Careful opioid use. Prophylactic antiemetics may be used if needed. |
| Local Anesthesia | Numbs a small, targeted area for minor procedures (e.g., stitches, dental work). | Least likely to cause systemic side effects like nausea and vomiting, as its effects are localized. | Systemic nausea is rare. Treatment usually only required for local pain or discomfort. |
Conclusion
While the prospect of feeling sick after a procedure is a valid concern, the answer to 'Can going under anesthesia make you sick?' is more nuanced than a simple yes. It is a common side effect, but modern pharmacology and advanced anesthetic techniques have significantly improved patient outcomes. Anesthesiologists are highly trained to identify patients at risk and implement personalized plans using a range of medications and techniques to prevent and treat nausea effectively. Communication with your anesthesiologist about any past experiences or fears is the most effective way to ensure a comfortable recovery. For more detailed information on anesthetic effects, refer to resources from the American Society of Anesthesiologists.
