It's the problem that won't go away. Despite reams of research and several excellent antiemetics, post-operative nausea and vomiting remains a difficult complication to effectively manage in the outpatient setting. Beyond improving patient satisfaction, managing and controlling PONV helps prevent serious post-operative complications. If inadequately treated, it can result in delayed discharge, the necessity for re-operation and perhaps hospital admission.

While preventing PONV is of concern to all members of the surgical team, anesthesia providers should take the lead in developing a focused approach. Following is a discussion of the current treatment options for PONV, a review of the most recent consensus panel guidelines and a framework for setting sensible protocols for prevention at your facility.

Current treatment options
Non-pharmacologic treatment options for include acupuncture, acupressure[1,2] or aromatherapy with peppermint or isopropyl alcohol.[3,4] Acupuncture and aromatherapy, says the research, are promising applications for PONV prevention currently being investigated, but are difficult techniques to master and lack proven clinical effectiveness. For now, both remain controversial (see "Aromatherapy: Are Scents Strong Enough to Stop PONV?" on page 32).

Droperidol has a well-documented history of effectiveness for prevention of PONV.[5,6] But since the well-publicized issuance of a black box warning by the FDA in 2001 that linked droperidol with fatal cardiac arrhythmias, its use for the prevention and treatment of PONV has declined.[7] This despite the questioning of the warning's validity, especially for droperidol doses less than 1.25mg.[5,8]

Antihistamines (dimenhydrinate, diphenhydramine, cyclizine, and hydroxyzine) have been used to manage PONV.[9] Metoclopramide is often used for prophylaxis of PONV, but has not been shown to be an effective option.[10] Transdermal scopolamine, meanwhile, is known to be a safe and effective drug regimen.[11,12] Dexamethasone is also an effective therapeutic agent without significant adverse events when used in single-dose therapy.[13] The serotonin type 3 receptor antagonists (5-HT3RA) ' ondansetron, granisetron, dolasetron and palonsetron ' are widely prescribed and have been shown to be quite effective with minimal side effects.[14] A new category of agents, neurokinin-1 receptor antagonists (aprepitant,15 CP-12272116 and GR20517117), is currently being considered PONV management.

Employing a predictive methodology to identify patients at greatest risk for PONV and those patients who'd most benefit from these prophylactic antiemetic therapy options is effective. A simplified PONV risk scoring system published in 1999[18] identified four factors that are highly predictive for PONV:

• female gender;
• history of motion sickness or PONV;
• non-smoking status; and
• intended use of postoperative opioids.

Research showed that when one, two, three or four of these risk factors are present (see "Simplified Risk Scoring System" above), the corresponding incidences of PONV were 21 percent, 39 percent, 61 percent and 79 percent, respectively (see "PONV Based on Number of Risk Factors" below). Sometimes simpler is better. This relatively basic risk assessment system has been found to be more accurate than more complex systems.[19,20]

A step-by-step assessment
In 2003, a multidisciplinary panel of experts developed and published consensus guidelines for managing PONV along with a management algorithm (see "Algorithm for PONV Prophylaxis" on page 32).[21] The recommendations from the panel direct therapy based on the degree of risk, with PONV prophylaxis therapy escalating in relation to patients' risk factors. Patients at low risk generally don't need to receive prophylaxis. Patients at moderate risk should receive either monotherapy or combination therapy for prophylaxis. Patients at high risk should be given combination prophylactic therapy, preferably from different therapeutic classes (see "Therapeutic Considerations for PONV Prophylaxis" on page 32).

The American Society of PeriAnesthesia Nurses published an evidence-based clinical practice guideline for the prevention or management of PONV and post-discharge nausea and vomiting in 2006.[22] At a minimum, any strategy to prevent PONV should include the following protocols.[23,24]

• Determination of PONV risk. Using the simplified risk scoring system, assess the patient's risk for PONV. Simply use pre-op questionnaires completed by the patient or during pre-op assessments performed by the nursing staff.
• Make appropriate use of antiemetic agents. Minimize emetogenic stimuli by the selection and dosing of anesthetic agents. After assessing the patient's PONV risk, select dosing agents and protocols that match that risk. Consider regional anesthesia or the use of propofol to induce and maintain general anesthesia. Combination anti-emetic therapy improves efficacy for PONV prevention and treatment. In difficult cases, the need may arise to suppress several central neuroemetic receptors through the use of combination antiemetic therapy.[23] Patients at moderate to high risk for PONV benefit from the administration of a prophylactic antiemetic agent that blocks one or more of the following receptors: dopamine type 2, serotonin type 3, histamine type 1 and muscarinic cholinergic type 1. Effective agents include transdermal scopolamine, prochlorperazine, promethazine, droperidol, ondansetron, dolasetron, granisetron and dexamethasone. In high-risk patients, combining two or more antiemetics with different mechanisms of action has been shown to be more effective than using a single agent.[25]
• Maintain adequate pain control. Steps you take to minimize the need for post-op pain medications, particularly opioids, will decrease the risk of PONV. Non-steroidal anti-inflammatory drugs reduce pain without high incidence of PONV. Due to an increased chance of post-op bleeding, however, anesthesia providers must consult with surgeons before beginning an NSAID pain-control regimen.
• Provide adequate IV hydration. The amount of required IV hydration depends on the type of procedure, length of the case and the patient being operated on. The longer and more complicated the procedure, the more hydration the patient requires to offset the considerable loss of blood. For pediatric patients, administering 30cc per kg of actual body weight during the procedure or for the first hour post-op can lower the risk of PONV. Adult patients usually require a little less, between 15cc and 20cc per kg actual body weight.
• Employ non-pharmacologic techniques. Aromatherapy and acupuncture are not yet proven to effectively reduce PONV risk on their own, but the techniques can be used in combination with drug therapy. Currently, these non-pharmacologic techniques are more of a supplemental agent than primary course of action.
• Make it a group effort. Adopt and modify PONV treatment guidelines to the specifics of your center. Start by establishing a consensus between the surgeons, anesthesia providers and PACU nurses. Each facility and each practitioner employs various techniques and protocols to lower PONV risk. Surgeons and anesthesia providers who work at several centers may have varying ideas on the best techniques for PONV management. It's essential to get everyone on the same page.

The specifics of the medications you choose should follow the consensus guidelines based on the availability and preferences of the clinicians in your practice. Because antiemetic interventions are similarly effective and act independently, first use the safest or least expensive. Prophylaxis is rarely warranted in low-risk patients; moderate-risk patients may benefit from a single intervention and multiple interventions should be reserved for high-risk patients.[26]

A consistent approach is required to measure the efficacy of the interventions you use. If you administer various approaches to PONV prevention indiscriminately, it's nearly impossible to determine which protocols have a positive effect on patient outcomes. Systematically applying guidelines to the patients in your practice with a methodology for follow-up and analysis of quality improvement should result in an effective and sensible protocol for the prevention of PONV.

A select group
Getting facilitywide buy-in is sometimes difficult, especially when dealing with physicians who resist change. Recently, staff at my facility gathered to address our PONV protocols. The surgeons, nurses and anesthesia providers agreed to use Decadron (dexamethasone) for PONV prophylaxis. Some physicians were immediately against the idea. We tried to convince the opposition to use the drug, but didn't press the issue. Instead, we worked with those who were willing and recorded the overwhelmingly positive results. When the physicians who originally hesitated to make the switch saw how well the patients reacted to the therapy, they quickly asked to add the drug to their treatment options. Often, documented success will be the spark to evoke change.

Regardless of which prevention regimen you employ, be selective with its administration. All patients should not receive PONV prophylaxis. By first assessing and separating low-risk patients from those that are high risk, you'll focus your staff's energy and facility's resources on patients most likely to experience PONV. A definitive answer to treating this common complication may not exist, but you can optimally manage PONV if you take a practical, systematic approach.

References:
1. Chernyak GV, Sessler DI. Perioperative acupuncture and related techniques. Anesthesiology. 2005;102:1031-49.
2. Lee A, Done ML. Stimulation of the wrist acupuncture point P6 for preventing postoperative nausea and vomiting. Cocrane Database Sys Rev. 2004:CD003281.
3. Chiravalle P, McCaffrey R. Alternative therapy applications for postoperative nausea and vomiting. Holistic Nursing Practice. 2005;19:207-10.
4. Smiler BG, Srock M. Isopropyl alcohol for transport-related nausea. Anesthesia and Analgesia. 1998;87:1214.
5. Habib AS, Gan TJ. Food and drug administration black box warning on the perioperative use of droperidol: a review of the cases. Anesthesia and Analgesia. 2003;96:1377-9.
6. Henzi I, Sonderegger J, Tramer MR. Efficacy, dose-response, and adverse effects of droperidol for prevention of postoperative nausea and vomiting. Canadian Journal of Anaesthesia. 2000;45: 537-51.
7. U.S. Food and Drug Administration. FDA Talk Paper. FDA strengthens warnings for droperidol. December 5, 2001. Available at: www.fda.gob/bbs/topics/ANSWERS/2001/ANS01123.html. Accessed June 30, 2007.
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12. Bailey PL, Streisand JB, Pace NL, et al. Transdermal scopolamine reduces nausea and vomiting after outpatient laparoscopy. Anesthesiology. 1990:72:977-80.
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16. Gesztesi Z, Scuderi PE, White PF, et al. Substance P (neurokinin-1) antagonist prevents postoperative vomiting after abdominal hysterectomy procedures. Anesthesiology. 2006;93:931-7.
17. Diemunsch P, Schoeffler P, Bryssine B, et al. Antiemetic activity of the NK1 receptor antagonist GR205171 in the treatment of established postoperative nausea and vomiting after major gynaecological surgery. British Journal of Anaesthesia. 1999;82:274-6.
18. Apfel CC, Laara E, Koivuranta M, Grein CA, Roewer N. A simplified risk score for predicting postoperative nausea and vomiting: conclusions from cross-validations between two centers. Anesthesiology. 1999;91:693-700.
19. Apfel CC, Kranke P, Eberhart LHJ, Roos A, Roewer N. Comparison of predictive models for postoperative nausea and vomiting. British Journal of Anaesthesia. 2002;88:234-40.
20. Pierre S, Benais H, Pouymayou J. Apfel's simplified score may favourably predict the risk of postoperative nausea and vomiting. Canadian Journal of Anaesthesia. 2002;49: 237-42.
21. Gan TJ, Meyer T, Apfel CC, et al. Consensus guidelines for management of postoperative nausea and vomiting. Anesthesia and Analgesia. 2003;97:62-71.
22. American Society of PeriAnesthesia Nurses. ASPAN's evidence-based clinical practice guideline for the prevention and/or management of PONV/PDNV. Available at: http://www.aspan/ponv_pdnv_guidelines.htm. Accessed June 30, 2007.
23. Kovac AL. Prevention and treatment of postoperative nausea and vomiting. Drugs. 2000;59:213-43.
24. Gan TJ. Postoperative nausea and vomiting'can it be eliminated? Journal of the American Medical Association. 2002;287:1233-6.
25. Golembiewski J, Chernin E, Chopra T. Prevention and treatment of postoperative nausea and vomiting. American Journal of Health-System Pharmacy. 2005; 62:1247-60.
26. Apfel CC, Korttila K, Abdalla M, et al. A factorial trial of six interventions for the prevention of postoperative nausea and vomiting. New England Journal of Medicine. 2004;351: 1458-9.