SMELL OF RELIEF Aromatherapy is just one of the many measures at your disposal to prevent post-operative nausea and vomiting.

How much do patients dread feeling nauseated after they emerge from anesthesia? My research has shown that many patients would be willing to pay $100 out of pocket to avoid experiencing post-operative nausea and vomiting (PONV). The downstream impact of their sick feelings might turn your stomach, too. Vomiting can delay discharge by 20 minutes and the cost of treating PONV is 100 times higher than preemptive therapy with a generic antiemetic. The good news: You can help keep recovering patients feeling fine by following the Society for Ambulatory Anesthesia's recently issued PONV management guidelines, which I helped author (osmag.net/jTEF6h). Here are some highlights from the updated recommendations that you should incorporate into your anesthesia routines.

Identifying likely sufferers
We all know the traditional PONV risk factors: female sex, a history of PONV or motion sickness, non-smokers and post-op opioids. The new guidelines add another risk factor to the list: patients younger than 50. You should determine the need and use of antiemetics on each patient's baseline risk score. Those with 3 or more of the above risk factors are at high risk of PONV, putting the likelihood that they'd experience it at between 60 and 80%. Although patients who undergo surgery in the outpatient setting are at lower risk of PONV, they are at significant risk of experiencing post-discharge nausea and vomiting (PDNV). In addition to the same risk factors for PONV, patients who experience nausea in the PACU are most likely to suffer PDNV.

Reducing the baseline risk
Once you know which patients are more likely to suffer PONV, then it's time to reduce the risk. These interventions have proven effective.

• Limit general anesthesia. Volatile anesthetics and nitrous oxide are among the most likely causes of PONV. When possible, opt for regional anesthesia instead of general anesthesia; research has shown that patients who receive regional anesthesia are 9 times less likely to experience PONV.
• Avoid opioids. Post-op opioids increase the risk of PONV in a dose-dependent manner — one-third of patients treated with powerful painkillers will feel nauseated. NSAIDs and cyclooxygenase-2 inhibitors help reduce opioid use during post-op recovery.
• Add propofol. Combining propofol with total IV anesthesia (TIVA) reduces PONV risk by 25%. Using propofol during the induction and maintenance of general anesthesia decreases the risk of early onset PONV. Administering a 1-mg bolus of propofol followed by an infusion of 20 mcg/kg/min also reduces the overall risk of PONV.
• Don't count on neostigmine. Although avoiding the use of the muscle relaxant reversal agent neostigmine has long been viewed as a way to reduce the risk of PONV, new research shows the drug's effects are minimal. The latest SAMBA guidelines remove it from the list of ways to reduce the baseline risk of PONV.

LOCAL STOP Placing regional blocks instead of administering general anesthesia is one way to help lower PONV risks.

REDUCE THE RISK
6 Practical Ways To Prevent PONV

• Use regional anesthesia in place of general anesthesia when possible.
• Use propofol for induction and maintenance of anesthesia.
• Avoid nitrous oxide.
• Avoid volatile anesthetics.
• Use intraoperative and post-op opioids sparingly.
• Ensure adequate hydration.

— TJ Gan, MD

Effective combinations
The updated guidelines included several newer drugs that have proven effective in lowering PONV risk: the 5-HT3 receptor antagonists ramosetron and palonosetron; the NK-1 receptor antagonists aprepitant, casopitant and rolapitant; the corticosteroid methylprednisolone; the butyrophenone haloperidol; and the antihistamine meclizine.

Adult patients at moderate risk of PONV should receive combination therapy with antiemetics that target different receptors. There is no one combination that works better than others, but combinations involving ondansetron with droperidol or dexamethasone are the most often studied. To reduce PONV risk by 25%, try this one-two punch — give dexamethasone 4 mg at induction, and ondansetron 4 mg and droperidol 1.25 mg at the end of surgery.

Using 5-HT3 receptor antagonists with dexamethasone or droperidol, or droperidol combined with dexamethasone, outperforms use of either drug alone. The combinations of 5-HT3 receptor antagonists plus droperidol, 5-HT3 receptor antagonists plus dexamethasone, and droperidol plus dexamethasone are similarly effective in reducing PONV.

Droperidol, which is similar to many 5-HT3 antagonists, has an FDA black box warning regarding its potential to prolong QT interval. Although its efficacy has been proven, it's not commonly used due to the black box warning and is in short supply.

A multimodal approach involving 2 or more interventions is most effective in high-risk patients. For example, opt for regional or TIVA with propofol over general anesthesia. Also administer antiemetic agents from different classes to optimize their effects.

If patients fail to respond to the action of a primary antiemetic, switch to another agent with a different mechanism of action. If they haven't received prophylactic antiemetic therapy, treat vomiting with the oral NK-1 receptor antagonist aprepitant and nausea with the 5-HT3 receptor antagonists ramosetron and palonosetron.

Scopolamine patches are effective options for preventing PONV, especially before ambulatory surgery, but aren't optimal for treatment once the symptoms manifest, because it takes 3 or 4 hours for the patches to reach maximum efficacy. Aromatherapy is certainly a viable preventative measure worth exploring, but the data is not solid on its overall impact.

One-third of patients who undergo outpatient surgery experience nausea and vomiting after they're discharged to home, where they don't have access to therapy. That's a significant issue, one that researchers are trying to solve. Current efforts to reduce incidence of PDNV focus on administering IV and oral doses of antiemetics at various times throughout the perioperative period. For example, administering dexamethasone 8 mg IV at induction, ondansetron 4 mg IV at the end of surgery and oral ondansetron 8 mg post-operatively is more effective than administering ondansetron 4 mg IV alone at the end of surgery.

Should you administer antiemetics to low-risk patients — those with 1 or no risk factors? No. Doing so puts them at unnecessary risk of experiencing side effects related to the therapy and adds unnecessary expense to their treatment. While the SAMBA guidelines advise against giving antiemetic agents to all patients, regardless of their baseline risk, they do acknowledge that the addition of less expensive generics to the market (ondansetron, for example) offers the possibility of a more widespread use of prophylactic antiemetic therapies.

STICK TO IT Scopolamine patches offer effective prophylactic effects, especially in the outpatient setting.

Solving the problem
CMS has added PONV risk assessment and prevention to the Physician Quality Reporting System. That means anesthesiologists have to document patients' PONV risk factors and, if they have 2 or more, administer prophylactic antiemetic agents. The evolution to pay for performance will be based in part on the appropriate administration of preventative antiemetic therapy according to the PONV risk scoring system, so the stakes have been raised in the effort to prevent patients from feeling sick after surgery.

The incidence of PONV is increasing as outpatient facilities attempt to recover and mobilize patients faster. Research has shown that PACU staff members recognized symptoms of PONV only 42% of the time and that only about one-third of patients at medium to high risk of experiencing PONV were administered appropriate preventative measures. Those findings suggest that incorporating multimodal prevention strategies into your facility's anesthesia routines will help ensure that high-risk patients receive antiemetic interventions. Once that general approach is established, your anesthesia providers can implementing a risk-based model.

We need to standardize our efforts to manage PONV. That doesn't mean every patient should receive the same preventative treatment, regardless of risk factors. But limiting variability across caregivers and facilities would let us track and identify the most effective treatments. A consistently applied strategy that selects antiemetics based on a patient's risk factors, and dictates which treatment to use when prophylaxis fails, would help to reduce the incidence of PONV. OSM