science

Postoperative nausea and vomiting

Postoperative nausea and vomiting is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Postoperative nausea and vomiting rather than just read about it. In short: Postoperative nausea and vomiting (PONV) is the common complication of nausea, vomiting, or retching experienced by a person within the first 24 hours following a surgical procedure. Untreated, PONV affects about 30% of people undergoing general anesthesia each year, with rates rising to 70–80% among those considered high-risk.

Key takeaways

Postoperative nausea and vomiting belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Postoperative nausea and vomiting to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Postoperative nausea and vomiting from memory before moving on to harder problems.

Reference excerpt

Postoperative nausea and vomiting (PONV) is the common complication of nausea, vomiting, or retching experienced by a person within the first 24 hours following a surgical procedure. Untreated, PONV affects about 30% of people undergoing general anesthesia each year, with rates rising to 70–80% among those considered high-risk. Postoperative nausea and vomiting can be highly distressing for people undergoing surgery and may pose significant barriers towards recovery, cause surgical complications, and result in delayed discharge from the surgical center if not managed properly.

Cause

Risk factors Risk factors for PONV can be classified into three main categories: patient-related, surgical, and anesthetic-related.

Patient-related Patient factors that confer increased risk for PONV include female gender, younger age (<16 years old), obesity, non-smoking status, high levels of preoperative anxiety, and prior history of PONV, motion sickness, or chemotherapy-induced nausea. The Apfel risk-scoring system is commonly used to sensitively and specifically determine the risk of PONV in adults. This simplified scoring system considers four primary predictors:

Female sex (most reliable) Non-smoking status History of PONV or motion sickness Post-operative opioid use The presence of 0, 1, 2, 3, or 4 factors corresponds to PONV risks of approximately 10%, 20%, 40%, 70%, and 80%, respectively. Research has also shown a genetic disposition towards PONV. Certain procedure types such as gynecological, abdominal, laparoscopic, ENT surgeries, and strabismus surgery in children are associated with a modestly increased risk of PONV versus other general surgical procedures.

Anesthetic-related The type of anesthetic medication plays a role in the risk for nausea and vomiting after surgery. Several medications routinely used in anesthesiology are believed to contribute to nausea and vomiting by acting on the highly sensitive chemoreceptor trigger zone (CTZ) located in the area postrema in the medulla oblangata, although the exact mechanisms remain poorly understood. Prolonged exposure to these drugs, namely volatile anesthetics, nitrous oxide (N2O), physostigmine, and opioids has been found to be correlated with increased PONV risk. The approach taken to anesthesia may also play a role in the risk of nausea and vomiting post-operatively. A significant body of evidence indicates that total intravenous anesthesia (TIVA) using propofol for induction and maintenance can reduce the incidence of postoperative nausea and vomiting significantly in both adults and children (3.5-fold vs. 5.7-fold reduction respectively) in comparison to volatile-anesthetic based techniques. Regional anesthesia has also demonstrated better outcomes for patients when compared to its general counterpart.

Mechanism The pathophysiology of PONV is mediated by several key neurotransmitters, including histamine, dopamine, serotonin, acetylcholine, and the more recently recognized neurokinin-1 (substance P). Pharmacologic stimulation of different chemoreceptors in the brain trigger different pathways that can result in PONV. Additionally, direct surgical manipulation of the vestibular system (cranial nerve VIII) or gastrointestinal structures innervated by the vagus nerve (cranial nerve X) can further activate the neural pathways involved in precipitating nausea and vomiting.

Prevention Key strategies in the prevention of postoperative nausea and vomiting include diligent risk assessment and stratification, use of non-volatile anesthetic techniques when feasible, provision of preventative medications based on risk, and employment of multimodal, opioid-sparing techniques for surgical pain control. Optimizing intravascular fluid volume during surgery is another strategy to reduce the risk of PONV, often achieved by administering additional IV fluids under general anesthesia. This approach addresses the fluid deficit caused by preoperative fasting, which typically restricts oral fluid intake for 2–6 hours before surgery. There is some evidence that providing the person undergoing anesthesia with supplemental perioperative intravenous crystalloids may reduce vomiting and/or nausea in patients with certain characteristics (American Society of Anesthesiologists (ASA) class I and II patients). The potential risks and other adverse effects with this type of therapy are unknown. For minor surgical procedures, more research is needed to determine the risks and benefits of this approach.

Management Commonly administered medications like serotonin receptor antagonists (ondansetron), corticosteroids (dexamethasone), and neurokinin-1 receptor antagonists (aprepitant) primarily act by modifying the release and activity of the aforementioned neurotransmitters involved in nausea and vomiting, effectively reducing the incidence of PONV. Using a multimodal approach by combining drugs targeting different receptors involved in PONV has been shown to be more efficacious than monotherapy. However, numerous patient factors, adverse side effects, and cost-effectiveness of these medications must be taken into consideration when selecting a treatment regimen. Recent evidence has shown that alternative therapies may also play a role in decreasing the incidence of PONV when used in conjunction with conventional treatment.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Postoperative nausea and vomiting

Start with the simplest possible case. Write down what Postoperative nausea and vomiting claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Postoperative nausea and vomiting before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Postoperative nausea and vomiting ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Postoperative nausea and vomiting

In research: Postoperative nausea and vomiting appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Postoperative nausea and vomiting in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Postoperative nausea and vomiting is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anesthesia, Vomiting, so understanding it makes those chapters shorter.
In everyday life: Look for Postoperative nausea and vomiting outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Postoperative nausea and vomiting in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Postoperative nausea and vomiting means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Postoperative nausea and vomiting out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Postoperative nausea and vomiting in simple terms?

Why does Postoperative nausea and vomiting matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Postoperative nausea and vomiting?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Postoperative nausea and vomiting.