Are Nonpharmacologic Techniques Useful Alternatives to Antiemetic Drugs for the Prevention of Nausea and Vomiting?

In spite of the more widespread application of minimally invasive ("keyhole") surgical techniques and the availability of rapid and short-acting anesthetic, analgesic, and muscle relaxant drugs, postoperative nausea and vomiting (PONV) remains a common problem after surgery 1,2. In the ambulatory setting, PONV can delay discharge 3 and is a leading cause of unanticipated hospital admissions for both pediatric 4 and adult 5 outpatients. In addition, the occurrence of nausea after general anesthesia can prolong the stay of inpatients in the recovery room 6. Orkin reported that when prospective patients were asked what they would most want to avoid after surgery, more than 70% listed emetic symptoms as their primary concern. These subjects were willing to accept a variety of tradeoffs (including dysphoria, increased cost, decreased mental acuity, and even increased pain) to avoid PONV. Orkin F. What do patients want? Preferences for immediate postoperative recovery abstract. Anesth Analg 1992;74:S225. In considering approaches to minimizing PONV, most clinical investigations have focused on the use of prophylactic antiemetic drugs e.g., phenothiazine [7 and anticholinergic drugs 8, as well as dopamine 9 and serotonin 10 antagonists] and anesthetic techniques associated with a low incidence of PONV e.g., propofol-based sedative and anesthetic techniques [11,12, as well as avoiding opioid analgesics 13,14, nitrous oxide 15,16, and reversal drugs 17,18]. Of interest, other important factors which can also influence the incidence of PONV are often ignored e.g., hydration status [19, adequacy of pain control 20]. Concerns regarding the side effects associated with the use of traditional antiemetics 21,22 and the high cost of the newer drug 23,24 have led many practitioners to reexamine the use of nonpharmacologic techniques e.g., acupuncture [25, electroacupuncture 26, transcutaneous electrical nerve stimulation 27, acupoint stimulation 28, and acupressure 29] for the prevention of nausea and vomiting. In the current and February 1997 issues of Anesthesia & Analgesia, Stein et al. 30 and Fan et al. 31 describe the use of acupressure for the prevention of intra- and postoperative nausea and vomiting, respectively. In these two clinical studies, acupressure (a noninvasive alternative to acupuncture) was applied at the Neiguan (P6) acupoint throughout the perioperative period. Both investigative groups reported that acupressure was effective in reducing nausea and vomiting compared to a placebo (inactive device) or sham treatment (device applied in a non-P6 location). In addition, Stein et al. 30 suggested that P6 acupressure was as effective as metoclopramide, 10 mg intravenously (IV), in preventing intraoperative nausea during spinal anesthesia. The choice of control groups used in these protocols can be criticized e.g., a placebo wrist band without a pressure button [30 and a loosely applied acupressure band with the stimulation applied in an inappropriate location 31]. However, it is virtually impossible to design a truly doubleblind, placebo (or sham)-controlled study when investigating nonpharmacologic therapeutic techniques such as acupressure. This is a very important issue because the clinical benefits associated with this type of treatment appear to be related in part to a placebo-type mechanism. Since the acupressure bands used in the control groups did not provide comparable stimulation at a nonacupoint site, the importance of applying the pressure at a specific acupoint (versus a nonacupoint) location was not evaluated in these studies. Although Dundee and Ghaly 32 suggested that the timing of acupressure stimulation was an important determinant of its antiemetic efficacy, the relative importance of intraoperative versus postoperative stimulation also remains to be determined. Additional studies are clearly needed to assess the relative importance of these factors in the successful application of acupressure as a prophylactic antiemetic therapy. Furthermore, well-controlled studies comparing acupressure with standard doses of the commonly used prophylactic antiemetics (e.g., droperidol, 0.625 mg IV, and ondansetron, 4 mg IV), are needed. Although small doses of metoclopramide (10 mg IV) possess antiemetic activity during regional anesthesia 33, this dose of metoclopramide has not been found to be very effective in preventing PONV 7,34. Future studies involving noninvasive acustimulation techniques e.g., sensory afferent stimulation [35] should include a sham (control) group that receives the same type and intensity of stimulation at a comparable "nonacupoint" location. In comparing acustimulation to the most widely used prophylactic antiemetic drugs (i.e., metaclopramide, droperidol and ondansetron), it would be useful to include a pharmacoeconomic analysis 23. Recent studies have suggested that small-dose droperidol, 0.625 mg IV, is more cost-effective than ondansetron, 4 mg IV, or metoclopramide, 10 mg IV, for routine prophylactic antiemetic therapy 23,36. However, the cost-effectiveness of ondansetron relative to other antiemetic therapies is also influenced by the dose and the timing of its administration 37,38, as well as the type of surgical procedure being evaluated 39. While potentially more effective antiemetic drugs are likely to be introduced into clinical practice in the near future (e.g., the 5-hydroxytryptamine type 3 antagonists, and the neurokinin NK-1 antagonists), the usefulness of simple, inexpensive, noninvasive approaches to the treatment and prevention of nausea and vomiting should not be overlooked as practitioners continue to search for more cost-effective approaches to improving patient outcome. Although there is no obvious mechanism to explain the apparent efficacy of acupressure stimulation in reducing nausea and vomiting, it has been demonstrated that acupoint stimulation using a transcutaneous electrical nerve stimulation device can increase levels of endogenous analgesic-like substances within the central nervous system 40. More than 20 years ago, Anderson and Krohg 20 demonstrated that the relief of pain led to the resolution of emetic symptoms in over 80% of patients experiencing both pain and nausea in the early postoperative period. Future studies involving acupoint stimulation should carefully examine the relationship between pain and emesis. While many practitioners still consider nausea and vomiting to be a "minor" complication associated with anesthesia and surgery, it remains "a big, 'little,' problem" 42 for many of our patients.