Briggs P, Hawrylack H, Mooney R. Inhaled peppermint oil for postop nausea in patients undergoing cardiac surgery. Nursing. 2016;46(7):61-67.

General surgery anesthesia is often followed by postoperative nausea and vomiting (PONV). PONV is a concern because it can cause multiple complications such as dehydration, suture tension, bleeding, and surgical site strain. PONV is often treated with antiemetic pharmaceuticals, but they can cause drowsiness, dysrhythmias (irregular heart rhythm), and increased risk of pneumonia. Several studies have reported that peppermint (Mentha × piperita, Lamiaceae) leaf essential oil relieves postoperative nausea. The advantages of peppermint oil compared with a pharmaceutical antiemetic in treating PONV are that it is less expensive, has a rapid onset, and can be self-administered. The purpose of this open-label study was to evaluate the benefits of inhaled peppermint essential oil in patients with nausea after cardiac surgery.

Cardiac surgery patients (mean age, 66 years) were recruited from the Christiana Care Health System; Newark, Delaware (dates of study not reported). Included patients were ≥ 18 years old, understood and spoke English, were willing to try aromatherapy, and underwent cardiac surgery. Excluded patients had an allergy to peppermint or did not give informed consent. Power calculations indicated a sample size of at least 30 patients was required. A total of 123 patients consented to participate, but only 34 patients experienced postoperative nausea and were treated with peppermint oil. Nurses prepared plastic nasal inhaler tubes containing an absorbent cotton wick with 3 drops of peppermint essential oil (manufacturer and concentration not reported). When not in use, the inhaler was kept in a sealed plastic bag. Patients did not share rooms, so there was no risk of patients influencing each other.

When patients first experienced nausea after surgery, they were asked to rate their nausea on a PONV scale of 0 to 5. Then, the patients were given the peppermint inhaler and taught how to use it. Patients were instructed to place the inhaler in 1 nostril, push the other nostril closed with their fingers, and inhale deeply through their open nostril for 3 seconds. Following inhalation, they were told to hold their breath for 3 seconds and exhale through pursed lips for a count of 3. Two minutes after using the inhaler, patients re-assessed nausea on the PONV scale. If the nausea was not relieved, the treatment was repeated (time interval not reported). Patients could ask for a pharmaceutical antiemetic at any time. Following treatment with peppermint, satisfaction was surveyed, and patients were asked whether they would use peppermint aromatherapy again and whether it should be a treatment option.

After using the inhaler 1 time, 55.8% of the patients had no nausea, and 23.5% had mild nausea. A paired analysis revealed a significant difference (P = 0.0001) between pre- and post-inhaler nausea. Five (14.7%) patients needed to use the inhaler a second time, and 4/5 (80%) were nausea-free after the second use. A total of 30 patients completed the post-treatment survey; 93% of patients were satisfied with peppermint oil therapy, 93% would try it again, and 90% thought it should be an option for PONV management.

One patient who received no relief from the second use of peppermint was treated with a prescription antiemetic and still had no relief of the nausea. Another patient who did not receive any nausea relief from peppermint was not willing to try it again and did not complete the survey.

The authors conclude that peppermint oil inhalation is a cost-effective, fast-acting therapy and "is a viable first-line treatment for nausea in postoperative cardiac surgery patients." The authors explain that more patients were not eligible for inclusion because they were treated for nausea in the Intensive Care Unit (ICU) before reaching the "step-down" area where the study was conducted. Later, the protocol was amended to include patients in the ICU.

The researchers acknowledge that the study was limited because the large number of nurses involved limited their ability to oversee the administration of the protocol, and that baseline data on antiemetic drug use would have allowed the determination of whether peppermint aromatherapy decreased the overall use of antiemetic drugs. Another limitation of this study is that there was no control group, so a placebo effect cannot be ruled out. Based on the results of this study, peppermint inhalation is now routinely used as a non-prescription nursing intervention at the Christiana Care Health System. The authors report no conflict of interest.