- Email: [email protected]
The Effect of Aromatherapy on Postoperative Nausea in Women Undergoing Surgical Procedures
The Effect of Aromatherapy on Postoperative Nausea in Women Undergoing Surgical Procedures Luisa Ferruggiari, MS, RN, ANP-C, CPAN, Barbara Ragione, BS, RN, CPAN, Ellen R. Rich, PhD, RN, FNP, FAANP, Kathleen Lock, MBA Postoperative nausea and vomiting (PONV) is a common source of patient discomfort and decreased satisfaction. Aromatherapy has been identified as a complementary modality for the prevention and management of PONV. The purpose of this study was to assess the effect of aromatherapy on the severity of postoperative nausea (PON) in women undergoing surgical procedures in the postanesthesia care unit. Women complaining of PON received traditional antiemetics, inhalation of peppermint oil, or saline vapor. A visual analog scale was used to rate nausea at the first complaint; at 5 minutes after intervention; and, if nausea persisted, at 10 minutes after intervention. At both 5 and 10 minutes, statistical analysis showed no significant differences between intervention and nausea rating. Obtaining eligible subjects was challenging. Although many women consented, most received intraoperative antiemetics and did not report nausea postoperatively. Keywords: postoperative nausea and vomiting, aromatherapy, complementary modality, antiemetics, postanesthesia care unit, peppermint. Ó 2012 by American Society of PeriAnesthesia Nurses
POSTOPERATIVE NAUSEA AND vomiting (PONV) is a common cause of discomfort that contributes to patient dissatisfaction after surgery and may lead to an increased length of stay in the postanesthesia care unit (PACU).1 One-third of surgical patients each year experience PONV.2 Documented categories of greater risk for postoperative nausea are female gender, nonsmoker status, previ-
Luisa Ferruggiari, MS, RN, ANP-C, CPAN, Perioperative Acute Pain Service Adult Nurse Practitioner, Good Samaritan Hospital Medical Center, West Islip, NY; Barbara Ragione, BS, RN, CPAN, Coordinator of Nursing Informatics, Good Samaritan Hospital Medical Center, West Islip, NY; Ellen R. Rich, PhD, RN, FNP, FAANP, Professor, Molloy College, Rickville Centre, NY; and Kathleen Lock, MBA, Data Coordinator, Catholic Health Services of Long Island, Rockville Centre, NY, but was Performance Improvement Coordinator for Good Samaritan Hospital Medical Center in West Islip, NY, when this article was written. Conflict of interest: None to report. Address correspondence to Ellen R. Rich, Molloy College, 1000 Hempstead Avenue, PO Box 5002, Rockville Centre, NY 11571; e-mail address: [email protected]. Ó 2012 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2012.01.013
246
ous history of PONV, history of motion sickness, and duration of surgery longer than 60 minutes.3 Pharmacologic treatments for symptoms of postoperative nausea often vary in their effectiveness. Many drugs used to treat postoperative nausea are costly, have sedative effects, and may cause cardiac arrhythmias.4 Aprepitant, a neurokinin 1 receptor antagonist, has been recommended as a first-line treatment for PONV. However, its acquisition cost is relatively high, making it less appealing as a first-line agent.5 Classes of antiemetics such as the benzamides, phenothiazines, and antihistamines have sedative effects. The associated sedative side effects limit the use of antiemetics in outpatient surgical cases.6 Droperidol was recommended for administration at the end of surgery to patients at high risk for developing PONV.7 In 2001, the Food and Drug Administration issued a black box warning regarding potential for QT interval prolongation and cardiac arrhythmias that may result in torsades de pointes and sudden cardiac death, and droperidol use dropped dramatically.5,8 Ondansetron is classified
Journal of PeriAnesthesia Nursing, Vol 27, No 4 (August), 2012: pp 246-251
EFFECT OF AROMATHERAPY ON PON
247
as a serotonin antagonist, more specifically, a 5-HT3 receptor antagonist. It is used in the treatment of PONV and does not produce unwanted adverse effects such as sedation, dry mouth, and extra pyramidal symptoms that are associated with other traditional antiemetics.5
a 20-minute delay in PACU discharge that could result in a cost of several hundred million dollars per year.9 The purpose of this study was to assess the effect of aromatherapy with peppermint oil on the severity of postoperative nausea in women in the PACU after undergoing surgical procedures.
Patients often state that the fear of developing PONV outweighs the fear of pain they may experience postoperatively.1 Those patients who have had previous episodes of postoperative nausea tend to be most fearful of a recurrence. Gan et al9 found that patients recovering in PACUs were willing to pay an average of $56 to $100 for an antiemetic that would eliminate PONV.
Literature Review
Internet and media sources have fostered patients’ increased awareness of nontraditional therapies. This awareness has led to patient inquiries about alternative measures before surgery in an attempt to mitigate the occurrence of postoperative nausea. The US Department of Health and Human Services through the National Center for Complementary and Alternative Medicine has identified essential oil of peppermint as a complementary therapy for a variety of health conditions such as nausea, indigestion, and irritable bowel syndrome.10 Aromatherapy is defined as a treatment using scents.11 Aromatherapy with peppermint oil, considered a herbal remedy,10 is a nontraditional treatment modality added to the present conventional treatment options available for PONV.3 Inhalation of essential oils leads to systemic absorption by way of the nasal mucosa and lungs. It may take only minutes for essential oils to appear in the bloodstream after inhalation. Because essential oils are lipophilic, they are absorbed by the brain and nervous system.12 Mamaril et al13 cite the use of aromatherapy as a nontraditional option for the treatment of PONV. Aromatherapy using peppermint oil has been suggested as an effective and cost-efficient complementary therapy for nausea both postoperatively and in other health care settings.14 Potential advantages of aromatherapy with peppermint oil include rapid onset, ease of administration, and absence of any major side effects.10 Another advantage of aromatherapy is potential cost savings if aromatherapy can be shown to replace traditional antiemetics. For example, peppermint oil is inexpensive, but every episode of vomiting is related to approximately
The review of the literature related to PONV includes complementary treatment modalities such as aromatherapy. The American Society of Perianesthesia Nurses, recognizing the lack of a multimodal treatment approach to PONV, developed a clinical practice guideline in 2006.3 A strategic work team consisting of 16 multidisciplinary multispecialty experts convened and produced strong evidence-based recommendations regarding the prevention and/or management of PONV. Included in these recommendations were complementary treatment modalities listing aromatherapy as an appropriate rescue intervention.3 Research performed to date has been inconclusive regarding the effect of aromatherapy with peppermint oil. Existing studies are limited by very small group sizes. Tate14 divided 18 gynecologic surgery patients into three groups: control (no treatment), placebo (peppermint essence), and experimental (peppermint oil). Although some significant difference was found in postoperative nausea between the placebo and experimental groups (P 5 .0487), little can be inferred because of small sample size and numbers of confounding variables. Anderson and Gross4 divided 33 ambulatory surgery patients into three groups: aromatherapy with peppermint, isopropyl alcohol, and saline. Results indicated that aromatherapy significantly reduced the perceived severity of postoperative nausea in all three groups. The fact that a saline placebo was as effective as alcohol or peppermint suggested that the beneficial effect may have been related to controlled breathing practices rather than the actual aroma inhaled. Normal saline is free of scent, and there is no evidence in the literature that inhalation of saline vapor has an effect on nausea. Generalizability of the study by Anderson and Gross4 was limited because of a small sample size. The lack of literature supports a need for more research regarding the effect of peppermint oil aromatherapy on postoperative nausea.
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Design This study used a quasi-experimental design to evaluate the effect of aromatherapy with peppermint oil on postoperative nausea and vomiting in women undergoing surgical procedures. Aromatherapy was also compared with traditional antiemetics, the current standard of care in the institution, based on a recommendation by the institutional review board. The outcome measured was nausea severity. Independent variables were peppermint aroma vapor inhalation, normal saline vapor inhalation, and administration of a traditional antiemetic (ondansetron). The hypothesis for this study was that women receiving aromatherapy with peppermint oil would experience a greater reduction in postoperative nausea than those receiving aromatherapy with saline.
disease, or chronic respiratory conditions. Consent was obtained in the ambulatory surgery unit on the day of surgery. Consented subjects were advised that they could receive a dose of antiemetic on request, regardless of the group assignment; therefore, no one was deprived of medication if they desired it.
Methods
Peppermint and saline aroma bags were prepared according to the recipe at the beginning of the day in a separate room to avoid dispersion of the aroma. The pure peppermint oil was obtained from the hospital pharmacy department. Peppermint oil was never stored in the PACU. For those receiving inhalation, the investigators randomly selected a sealed zip lock bag from a box containing bags of both peppermint and saline aromas. After an inhalation, the zip lock bags were resealed to prevent any aroma from spreading throughout the PACU.
The study was approved by the hospital’s institutional review board. Postoperative nausea severity was operationalized by use of a visual analog scale (VAS) where subjects were asked to mark a 200mm horizontal line to note the degree of their nausea, with a range from ‘‘no nausea’’ at the 0-mm mark to ‘‘worst possible nausea’’ at the 200-mm mark. Peppermint aroma vapor inhalation consisted of one inhalation from a zip lock plastic bag containing four 2 3 2 gauze pads saturated with two drops of pure pharmacy-grade peppermint oil and 5 mL of 0.9% normal saline. Normal saline vapor inhalation consisted of one inhalation from a zip lock bag containing four 2 3 2 gauze pads saturated with 5 mL of 0.9% normal saline. The traditional antiemetic was operationalized as 4 mg of ondansetron delivered via intravenous push per physician’s standing orders.
The study protocol began when a subject complained of nausea postoperatively. At the first report of nausea, nausea severity was rated on the VAS. The investigator then instructed the subject to breathe deeply. The patient then received a traditional antiemetic, an inhalation of peppermint oil or saline vapor. For those receiving the traditional antiemetic, the nurse administered it as ordered. Five minutes after intervention, the subjects were asked to re-rate their nausea on the VAS. Subjects then had the option to take another inhalation of either the peppermint oil or saline vapor. Five minutes after the second inhalation, the nausea again was rated on the VAS. If the nausea persisted, the patient had the option to take additional inhalations or receive a traditional antiemetic. Data collection ended with the 10-minute postintervention assessment.
Other variables tracked were age, body mass index (BMI), type of surgery, and anesthetic technique. Risk factor variables for postoperative nausea were also collected including previous history of PONV, history of motion sickness, duration of surgery longer than 60 minutes, and history of smoking.
Findings
The sample comprised nonpregnant females older than 18 years undergoing a surgical procedure at a suburban community hospital. Exclusionary criteria were olfactory sensory loss, allergy to peppermint, asthma, chronic obstructive pulmonary
Consent was obtained from 612 women. Of those, only 71 reported postoperative nausea over the study period and were eligible for data collection. During the implementation of the study, anesthesia providers routinely administered prophylactic doses of antiemetics intraoperatively. Fewer women than expected complained of postoperative nausea. The final model consisted of 70 subjects, with 110 data points studied. There were 23 participants in the
EFFECT OF AROMATHERAPY ON PON
aromatherapy in the peppermint oil group, 22 in the saline vapor group, and 25 in the traditional antiemetic group. Differences in PON between the groups (traditional antiemetic, peppermint oil, and saline vapor) were evaluated using an analysis of covariance at 5 and 10 minutes after intervention. Baseline PON was used as a covariate in each model. Other covariates, including surgery type, anesthetic technique, history of PONV, history of motion sickness, duration of surgery, BMI, and history of smoking, were tested in each model. Covariates that attained a level of statistical significance of .05 were retained. A power analysis was conducted before the study. To achieve a power of 80%, it would have been necessary to have 57 subjects per group. However, because of intraoperative administration of antiemetics, we were unable to reach the projected target number of subjects during the study period. The models showed that at both 5 and 10 minutes, there were no statistically significant differences in nausea rating among the interventions (P 5 .79 at 5 minutes and P 5 .71 at 10 minutes). Table 1 shows the mean PON ratings. Although peppermint oil had a lower mean rating than the other interventions and the largest drop in PON rating at 10 minutes, there is insufficient statistical evidence to declare it significantly better because of the small sample sizes and large standard deviations. There is evidence that patients with a history of motion sickness have a higher nausea rating after surgery (P 5 .009 at 5 minutes and P 5 .063 at 10 minutes). Table 2 demonstrates this difference. Patients with a history of motion sickness experienced a smaller total drop in PON after intervention than those without such history (P 5 .006).
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None of the other covariates studied were found to have a significant impact on PON. Table 3 lists other covariates and their accompanying P values.
Discussion Target enrollment was projected as 30 participants per group. Only a small proportion of the large number of consenting subjects reported postoperative nausea. All study subjects received some type of antiemetic before admission to the PACU. It was noted that the administration of prophylactic antiemetics was based on the practice of the anesthesia provider and not on risk assessment for potential postoperative nausea. Staffing changes and low yield of eligible subjects led to the termination of data collection after 4 years, with subject totals below the desired amount. This clearly limits the power and generalizability of the study outcomes. Results demonstrated no significant differences between the type of intervention at 5 and 10 minutes. Interestingly, there was no significant difference in the nausea report between the patients in the group receiving peppermint or saline inhalations and those in the group receiving intravenous ondansetron. According to ondansetron prescribing information,15 mean peak plasma concentrations are achieved at 10 minutes after intravenous infusion. Couture et al16 discuss the role of supplemental oxygen in reducing overall incidence of PONV in the first 24 hours postoperatively. It is possible that the act of taking deep breaths may have moderated outcome. Although this study had a larger number of subjects than the works of Tate14 and Anderson and Gross,4 all three projects share the limitation of insufficient statistical power to generalize findings. In this study, the lack of significant
Table 1. Mean Nausea Ratings by Intervention Group (N, SD) Treatment
Mean Rating: Baseline
Mean Rating: 5 min After Intervention
Mean Rating: 10 min After Intervention
Saline Peppermint oil Zofran
11.9 (22, 6.12) 12.5 (23, 5.92) 11.3 (25, 5.38)
7.5 (22, 6.52) 8.0 (23, 5.82) 6.8 (25, 6.71)
3.4 (8, 4.22) 2.4 (11, 2.94) 5.8 (21, 6.31)
SD, standard deviation.
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Table 2. Mean Nausea Ratings by Motion Sickness History (N, SD) Motion Sickness History
Mean Rating: Baseline
Mean Rating: 5 min After Intervention
Mean Rating: 10 min After Intervention
History of motion sickness No history of motion sickness
13.3 (10, 4.89) 11.6 (60, 5.87)
12.2 (10, 6.29) 6.6 (60, 5.99)
9.4 (6, 7.17) 3.5 (34, 4.51)
SD, standard deviation.
difference in nausea level between all three types of intervention at 5 and 10 minutes is reminiscent of the findings of Anderson and Gross4 and may point to the benefit of controlled breathing techniques. However, unlike that of Anderson and Gross,4 this study included a pharmacologic intervention. It was unexpected to find that there was no significant difference in nausea levels between peppermint oil, saline, and ondansetron. Future research could be aimed at further investigating the effectiveness of deep breathing techniques on PONV. This study provided subjects with the possibility to experience a natural remedy rather than a more traditional medical therapy. Obtaining consents from potential study participants was never difficult, and there were very few who declined to consent. An anecdotal observation was that consented patients were disappointed when they did not experience nausea and could not participate in the study. Aromatherapy is a complementary health modality. Guidelines embrace its use as an addition to standard medical care for relief of PONV.3 As research efforts continue to build evidence supporting the use of peppermint oil to relieve postoperative nausea, patient acceptance continues to be favorable Table 3. Levels of Significance for Other PON Covariates at 5 and 10 Minutes Significance Covariate Surgery type Anesthetic technique History of PONV Duration of surgery BMI History of smoking
5 min
10 min
.922 .113 .264 .354 .231 .520
.613 .139 .910 .850 .382 .645
PONV, postoperative nausea and vomiting; BMI, body mass index. Significance at P # .05.
and administration is safe. Although further research with larger samples is necessary, PACU nurses should consider adding this modality for their patients. Limitations Despite significant effort over a long period of time, the sample size fell short of the target number. Obtaining consent was not difficult, but because of intraoperative antiemetic administration, the proportion of subjects reporting nausea was small. Although this represents a good outcome for patients, it limited the team’s ability to evaluate a low-cost treatment that has a minimal incidence of side effects. Those reporting nausea after receiving intraoperative antiemetics may represent a refractory group whose symptoms were more severe and challenging to manage, thereby making them different than the general population. Effective postoperative management of PON could have been tracked more accurately in the absence of intraoperative antiemetic administration. The management of PON with pharmaceutical and alternative treatments is a complex phenomenon, and it is a challenge to isolate the effect of a single variable. Suggestions for Future Research Further investigation with a larger sample size is recommended. A multisite study could provide a more sizable cohort. Additional measures to control and track antecedent and intervening variables could yield more definitive results, including the effects of peppermint oil in the roles of both prophylaxis and rescue. If intraoperative antiemetic use is to remain the standard of care, it may be revealing to examine the characteristics of those who develop nausea in spite of being medicated and how they respond to complementary modalities for the treatment of PON.
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References 1. Darkow T, Gora Harper ML, Record KE, Goulson DT. Impact of antiemetic selection on postoperative nausea and vomiting and patient satisfaction. Pharmacotherapy. 2001;21:540-548. 2. Macario A, Weinger M, Carney S, Kim A. Which clinical anesthesia outcomes are important to avoid? The perspective of patients. Anesth Analg. 1999;89:652-658. 3. American Society for PeriAnesthesia Nurses. ASPAN’s evidenced-based clinical practice guideline for the prevention and/or management of PONV/PDNV. J Perianesth Nurs. 2006;4:230-250. 4. Anderson L, Gross J. Aromatherapy with peppermint, isopropyl alcohol, or placebo is equally effective in relieving postoperative nausea. J Perianesth Nurs. 2004;19: 29-35. 5. Golembiewski J, Tokumaru S. Pharmacological prophylaxis and treatment of adult postoperative/postdischarge nausea and vomiting. J Perianesth Nurs. 2006;21:385-397. 6. Noble K. Stop the spinning world: Postoperative nausea and vomiting. J Perianesth Nurs. 2006;21:431-435. 7. Le TP, Gan TJ. Update on the management of postoperative nausea and vomiting and post discharge nausea and vomiting in ambulatory surgery. Anesthesiol Clin. 2010;28:225-249. 8. Wilhelm SM, Dehoorne-Smith ML, Kale-Pradhan PB. Prevention of postoperative nausea and vomiting. Ann Pharmacother. 2007;41:68-78.
9. Gan TJ, Meyer T, Apfel CC, et al. Consensus guidelines for managing postoperative nausea and vomiting. Anesth Analg. 2003;97:62-71. 10. National Center for Complimentary and Alternative Medicine, National Institute of Health (2010). Herbs at a Glance: A Quick Guide to Herbal Supplements. Available at: http://nccam.nih.gov/health/NIH_Herbs_at_a_Glance. pdf. Accessed July 10, 2011. 11. Chiravalle P, Mc Caffrey R. Alternative therapy applications for postoperative nausea and vomiting. Holistic Nurs Pract. 2005;19:207-210. 12. Cristina ED. Understanding true aromatherapy: Understanding essential oils. Home Health Care Manag Pract. 2004;16:474-479. 13. Mamaril ME, Windle PE, Burkard JF. Prevention and management of postoperative nausea and vomiting: A look at complementary techniques. J Perianesth Nurs. 2006;21:404-410. 14. Tate S. Peppermint oil: A treatment for postoperative nausea. J Adv Nurs. 1997;26:543-549. 15. GlaxoSmithKline. Zofran Injection Prescribing Information. Available at: http://us.gsk.com/products/assets/us _zofran.pdf. Accessed April 11, 2011. 16. Couture DJ, Maye JP, O’Brien D, Smith AB. Therapeutic modalities for the prophylactic management of postoperative nausea and vomiting. J Perianesth Nurs. 2006;21:398-403.
POSTOPERATIVE NAUSEA AND vomiting (PONV) is a common cause of discomfort that contributes to patient dissatisfaction after surgery and may lead to an increased length of stay in the postanesthesia care unit (PACU).1 One-third of surgical patients each year experience PONV.2 Documented categories of greater risk for postoperative nausea are female gender, nonsmoker status, previ-
Luisa Ferruggiari, MS, RN, ANP-C, CPAN, Perioperative Acute Pain Service Adult Nurse Practitioner, Good Samaritan Hospital Medical Center, West Islip, NY; Barbara Ragione, BS, RN, CPAN, Coordinator of Nursing Informatics, Good Samaritan Hospital Medical Center, West Islip, NY; Ellen R. Rich, PhD, RN, FNP, FAANP, Professor, Molloy College, Rickville Centre, NY; and Kathleen Lock, MBA, Data Coordinator, Catholic Health Services of Long Island, Rockville Centre, NY, but was Performance Improvement Coordinator for Good Samaritan Hospital Medical Center in West Islip, NY, when this article was written. Conflict of interest: None to report. Address correspondence to Ellen R. Rich, Molloy College, 1000 Hempstead Avenue, PO Box 5002, Rockville Centre, NY 11571; e-mail address: [email protected]. Ó 2012 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2012.01.013
246
ous history of PONV, history of motion sickness, and duration of surgery longer than 60 minutes.3 Pharmacologic treatments for symptoms of postoperative nausea often vary in their effectiveness. Many drugs used to treat postoperative nausea are costly, have sedative effects, and may cause cardiac arrhythmias.4 Aprepitant, a neurokinin 1 receptor antagonist, has been recommended as a first-line treatment for PONV. However, its acquisition cost is relatively high, making it less appealing as a first-line agent.5 Classes of antiemetics such as the benzamides, phenothiazines, and antihistamines have sedative effects. The associated sedative side effects limit the use of antiemetics in outpatient surgical cases.6 Droperidol was recommended for administration at the end of surgery to patients at high risk for developing PONV.7 In 2001, the Food and Drug Administration issued a black box warning regarding potential for QT interval prolongation and cardiac arrhythmias that may result in torsades de pointes and sudden cardiac death, and droperidol use dropped dramatically.5,8 Ondansetron is classified
Journal of PeriAnesthesia Nursing, Vol 27, No 4 (August), 2012: pp 246-251
EFFECT OF AROMATHERAPY ON PON
247
as a serotonin antagonist, more specifically, a 5-HT3 receptor antagonist. It is used in the treatment of PONV and does not produce unwanted adverse effects such as sedation, dry mouth, and extra pyramidal symptoms that are associated with other traditional antiemetics.5
a 20-minute delay in PACU discharge that could result in a cost of several hundred million dollars per year.9 The purpose of this study was to assess the effect of aromatherapy with peppermint oil on the severity of postoperative nausea in women in the PACU after undergoing surgical procedures.
Patients often state that the fear of developing PONV outweighs the fear of pain they may experience postoperatively.1 Those patients who have had previous episodes of postoperative nausea tend to be most fearful of a recurrence. Gan et al9 found that patients recovering in PACUs were willing to pay an average of $56 to $100 for an antiemetic that would eliminate PONV.
Literature Review
Internet and media sources have fostered patients’ increased awareness of nontraditional therapies. This awareness has led to patient inquiries about alternative measures before surgery in an attempt to mitigate the occurrence of postoperative nausea. The US Department of Health and Human Services through the National Center for Complementary and Alternative Medicine has identified essential oil of peppermint as a complementary therapy for a variety of health conditions such as nausea, indigestion, and irritable bowel syndrome.10 Aromatherapy is defined as a treatment using scents.11 Aromatherapy with peppermint oil, considered a herbal remedy,10 is a nontraditional treatment modality added to the present conventional treatment options available for PONV.3 Inhalation of essential oils leads to systemic absorption by way of the nasal mucosa and lungs. It may take only minutes for essential oils to appear in the bloodstream after inhalation. Because essential oils are lipophilic, they are absorbed by the brain and nervous system.12 Mamaril et al13 cite the use of aromatherapy as a nontraditional option for the treatment of PONV. Aromatherapy using peppermint oil has been suggested as an effective and cost-efficient complementary therapy for nausea both postoperatively and in other health care settings.14 Potential advantages of aromatherapy with peppermint oil include rapid onset, ease of administration, and absence of any major side effects.10 Another advantage of aromatherapy is potential cost savings if aromatherapy can be shown to replace traditional antiemetics. For example, peppermint oil is inexpensive, but every episode of vomiting is related to approximately
The review of the literature related to PONV includes complementary treatment modalities such as aromatherapy. The American Society of Perianesthesia Nurses, recognizing the lack of a multimodal treatment approach to PONV, developed a clinical practice guideline in 2006.3 A strategic work team consisting of 16 multidisciplinary multispecialty experts convened and produced strong evidence-based recommendations regarding the prevention and/or management of PONV. Included in these recommendations were complementary treatment modalities listing aromatherapy as an appropriate rescue intervention.3 Research performed to date has been inconclusive regarding the effect of aromatherapy with peppermint oil. Existing studies are limited by very small group sizes. Tate14 divided 18 gynecologic surgery patients into three groups: control (no treatment), placebo (peppermint essence), and experimental (peppermint oil). Although some significant difference was found in postoperative nausea between the placebo and experimental groups (P 5 .0487), little can be inferred because of small sample size and numbers of confounding variables. Anderson and Gross4 divided 33 ambulatory surgery patients into three groups: aromatherapy with peppermint, isopropyl alcohol, and saline. Results indicated that aromatherapy significantly reduced the perceived severity of postoperative nausea in all three groups. The fact that a saline placebo was as effective as alcohol or peppermint suggested that the beneficial effect may have been related to controlled breathing practices rather than the actual aroma inhaled. Normal saline is free of scent, and there is no evidence in the literature that inhalation of saline vapor has an effect on nausea. Generalizability of the study by Anderson and Gross4 was limited because of a small sample size. The lack of literature supports a need for more research regarding the effect of peppermint oil aromatherapy on postoperative nausea.
FERRUGGIARI ET AL
248
Design This study used a quasi-experimental design to evaluate the effect of aromatherapy with peppermint oil on postoperative nausea and vomiting in women undergoing surgical procedures. Aromatherapy was also compared with traditional antiemetics, the current standard of care in the institution, based on a recommendation by the institutional review board. The outcome measured was nausea severity. Independent variables were peppermint aroma vapor inhalation, normal saline vapor inhalation, and administration of a traditional antiemetic (ondansetron). The hypothesis for this study was that women receiving aromatherapy with peppermint oil would experience a greater reduction in postoperative nausea than those receiving aromatherapy with saline.
disease, or chronic respiratory conditions. Consent was obtained in the ambulatory surgery unit on the day of surgery. Consented subjects were advised that they could receive a dose of antiemetic on request, regardless of the group assignment; therefore, no one was deprived of medication if they desired it.
Methods
Peppermint and saline aroma bags were prepared according to the recipe at the beginning of the day in a separate room to avoid dispersion of the aroma. The pure peppermint oil was obtained from the hospital pharmacy department. Peppermint oil was never stored in the PACU. For those receiving inhalation, the investigators randomly selected a sealed zip lock bag from a box containing bags of both peppermint and saline aromas. After an inhalation, the zip lock bags were resealed to prevent any aroma from spreading throughout the PACU.
The study was approved by the hospital’s institutional review board. Postoperative nausea severity was operationalized by use of a visual analog scale (VAS) where subjects were asked to mark a 200mm horizontal line to note the degree of their nausea, with a range from ‘‘no nausea’’ at the 0-mm mark to ‘‘worst possible nausea’’ at the 200-mm mark. Peppermint aroma vapor inhalation consisted of one inhalation from a zip lock plastic bag containing four 2 3 2 gauze pads saturated with two drops of pure pharmacy-grade peppermint oil and 5 mL of 0.9% normal saline. Normal saline vapor inhalation consisted of one inhalation from a zip lock bag containing four 2 3 2 gauze pads saturated with 5 mL of 0.9% normal saline. The traditional antiemetic was operationalized as 4 mg of ondansetron delivered via intravenous push per physician’s standing orders.
The study protocol began when a subject complained of nausea postoperatively. At the first report of nausea, nausea severity was rated on the VAS. The investigator then instructed the subject to breathe deeply. The patient then received a traditional antiemetic, an inhalation of peppermint oil or saline vapor. For those receiving the traditional antiemetic, the nurse administered it as ordered. Five minutes after intervention, the subjects were asked to re-rate their nausea on the VAS. Subjects then had the option to take another inhalation of either the peppermint oil or saline vapor. Five minutes after the second inhalation, the nausea again was rated on the VAS. If the nausea persisted, the patient had the option to take additional inhalations or receive a traditional antiemetic. Data collection ended with the 10-minute postintervention assessment.
Other variables tracked were age, body mass index (BMI), type of surgery, and anesthetic technique. Risk factor variables for postoperative nausea were also collected including previous history of PONV, history of motion sickness, duration of surgery longer than 60 minutes, and history of smoking.
Findings
The sample comprised nonpregnant females older than 18 years undergoing a surgical procedure at a suburban community hospital. Exclusionary criteria were olfactory sensory loss, allergy to peppermint, asthma, chronic obstructive pulmonary
Consent was obtained from 612 women. Of those, only 71 reported postoperative nausea over the study period and were eligible for data collection. During the implementation of the study, anesthesia providers routinely administered prophylactic doses of antiemetics intraoperatively. Fewer women than expected complained of postoperative nausea. The final model consisted of 70 subjects, with 110 data points studied. There were 23 participants in the
EFFECT OF AROMATHERAPY ON PON
aromatherapy in the peppermint oil group, 22 in the saline vapor group, and 25 in the traditional antiemetic group. Differences in PON between the groups (traditional antiemetic, peppermint oil, and saline vapor) were evaluated using an analysis of covariance at 5 and 10 minutes after intervention. Baseline PON was used as a covariate in each model. Other covariates, including surgery type, anesthetic technique, history of PONV, history of motion sickness, duration of surgery, BMI, and history of smoking, were tested in each model. Covariates that attained a level of statistical significance of .05 were retained. A power analysis was conducted before the study. To achieve a power of 80%, it would have been necessary to have 57 subjects per group. However, because of intraoperative administration of antiemetics, we were unable to reach the projected target number of subjects during the study period. The models showed that at both 5 and 10 minutes, there were no statistically significant differences in nausea rating among the interventions (P 5 .79 at 5 minutes and P 5 .71 at 10 minutes). Table 1 shows the mean PON ratings. Although peppermint oil had a lower mean rating than the other interventions and the largest drop in PON rating at 10 minutes, there is insufficient statistical evidence to declare it significantly better because of the small sample sizes and large standard deviations. There is evidence that patients with a history of motion sickness have a higher nausea rating after surgery (P 5 .009 at 5 minutes and P 5 .063 at 10 minutes). Table 2 demonstrates this difference. Patients with a history of motion sickness experienced a smaller total drop in PON after intervention than those without such history (P 5 .006).
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None of the other covariates studied were found to have a significant impact on PON. Table 3 lists other covariates and their accompanying P values.
Discussion Target enrollment was projected as 30 participants per group. Only a small proportion of the large number of consenting subjects reported postoperative nausea. All study subjects received some type of antiemetic before admission to the PACU. It was noted that the administration of prophylactic antiemetics was based on the practice of the anesthesia provider and not on risk assessment for potential postoperative nausea. Staffing changes and low yield of eligible subjects led to the termination of data collection after 4 years, with subject totals below the desired amount. This clearly limits the power and generalizability of the study outcomes. Results demonstrated no significant differences between the type of intervention at 5 and 10 minutes. Interestingly, there was no significant difference in the nausea report between the patients in the group receiving peppermint or saline inhalations and those in the group receiving intravenous ondansetron. According to ondansetron prescribing information,15 mean peak plasma concentrations are achieved at 10 minutes after intravenous infusion. Couture et al16 discuss the role of supplemental oxygen in reducing overall incidence of PONV in the first 24 hours postoperatively. It is possible that the act of taking deep breaths may have moderated outcome. Although this study had a larger number of subjects than the works of Tate14 and Anderson and Gross,4 all three projects share the limitation of insufficient statistical power to generalize findings. In this study, the lack of significant
Table 1. Mean Nausea Ratings by Intervention Group (N, SD) Treatment
Mean Rating: Baseline
Mean Rating: 5 min After Intervention
Mean Rating: 10 min After Intervention
Saline Peppermint oil Zofran
11.9 (22, 6.12) 12.5 (23, 5.92) 11.3 (25, 5.38)
7.5 (22, 6.52) 8.0 (23, 5.82) 6.8 (25, 6.71)
3.4 (8, 4.22) 2.4 (11, 2.94) 5.8 (21, 6.31)
SD, standard deviation.
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Table 2. Mean Nausea Ratings by Motion Sickness History (N, SD) Motion Sickness History
Mean Rating: Baseline
Mean Rating: 5 min After Intervention
Mean Rating: 10 min After Intervention
History of motion sickness No history of motion sickness
13.3 (10, 4.89) 11.6 (60, 5.87)
12.2 (10, 6.29) 6.6 (60, 5.99)
9.4 (6, 7.17) 3.5 (34, 4.51)
SD, standard deviation.
difference in nausea level between all three types of intervention at 5 and 10 minutes is reminiscent of the findings of Anderson and Gross4 and may point to the benefit of controlled breathing techniques. However, unlike that of Anderson and Gross,4 this study included a pharmacologic intervention. It was unexpected to find that there was no significant difference in nausea levels between peppermint oil, saline, and ondansetron. Future research could be aimed at further investigating the effectiveness of deep breathing techniques on PONV. This study provided subjects with the possibility to experience a natural remedy rather than a more traditional medical therapy. Obtaining consents from potential study participants was never difficult, and there were very few who declined to consent. An anecdotal observation was that consented patients were disappointed when they did not experience nausea and could not participate in the study. Aromatherapy is a complementary health modality. Guidelines embrace its use as an addition to standard medical care for relief of PONV.3 As research efforts continue to build evidence supporting the use of peppermint oil to relieve postoperative nausea, patient acceptance continues to be favorable Table 3. Levels of Significance for Other PON Covariates at 5 and 10 Minutes Significance Covariate Surgery type Anesthetic technique History of PONV Duration of surgery BMI History of smoking
5 min
10 min
.922 .113 .264 .354 .231 .520
.613 .139 .910 .850 .382 .645
PONV, postoperative nausea and vomiting; BMI, body mass index. Significance at P # .05.
and administration is safe. Although further research with larger samples is necessary, PACU nurses should consider adding this modality for their patients. Limitations Despite significant effort over a long period of time, the sample size fell short of the target number. Obtaining consent was not difficult, but because of intraoperative antiemetic administration, the proportion of subjects reporting nausea was small. Although this represents a good outcome for patients, it limited the team’s ability to evaluate a low-cost treatment that has a minimal incidence of side effects. Those reporting nausea after receiving intraoperative antiemetics may represent a refractory group whose symptoms were more severe and challenging to manage, thereby making them different than the general population. Effective postoperative management of PON could have been tracked more accurately in the absence of intraoperative antiemetic administration. The management of PON with pharmaceutical and alternative treatments is a complex phenomenon, and it is a challenge to isolate the effect of a single variable. Suggestions for Future Research Further investigation with a larger sample size is recommended. A multisite study could provide a more sizable cohort. Additional measures to control and track antecedent and intervening variables could yield more definitive results, including the effects of peppermint oil in the roles of both prophylaxis and rescue. If intraoperative antiemetic use is to remain the standard of care, it may be revealing to examine the characteristics of those who develop nausea in spite of being medicated and how they respond to complementary modalities for the treatment of PON.
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