Can Aromatherapy Relax Post-Op Patients?

Open heart surgery patients reported better sleep and less severe pain after their operation when they inhaled peppermint essence, a small clinical trial suggested.

Among 64 patients who underwent cardiac surgery, mean self-reported sleep quality scores on the first day after surgery were 20.10 in the group receiving peppermint aromatherapy and 25.76 in the placebo group, with lower scores indicating better sleep (P=0.0001).

Mean sleep scores were 18.63 versus 22.62 (P=0.009), respectively, on the second day, reported Ismail Azizi-fini, PhD, of the Kashan University of Medical Sciences in Iran, and co-authors in BMJ Supportive & Palliative Care.

On the 0-to-10 Numeric Pain Rating Scale, with lower scores indicating less pain, total mean pain scores over 2 days were 3.22 for the peppermint group and 4.56 for the placebo group (P=0.0001).

Peppermint essence is "not routinely used in special care units but considering the interesting effects of this substance and its results in this research, it can be added to care," Azizi-fini said in an email to MedPage Today.

"The nurses of the research departments were very surprised at how much easier their patients slept during the night," noted Azizi-fini, who said he had the idea for the study after speaking with a patient who had brought peppermint oil to help improve his pain and sleep after heart surgery.

"But the results of the research surprised all of us [in] that the sleep of the patients, especially the first two nights after the surgery -- when patients usually do not sleep well -- has become easier," he added.

Few studies have evaluated peppermint essential oil by itself, but in combination with other essential oils, limited studies have suggested that sleep quality may improve with aromatherapy, the researchers noted. Peppermint also has shown positive effects on insomnia.

Peppermint "can decrease fatigue, anxiety, heart rate, respiratory rate and blood pressure, increase the oxygenation of the lungs and brain, and improve sleep quality," Azizi-fini and colleagues wrote. In addition, "it may be that the analgesic effect of peppermint is due to its main components including carvone, limonene, and menthol," they noted. "The menthol in peppermint affects kappa opioid receptors and soothes the pain in return."

The study included patients from cardiac surgery departments of two teaching hospitals in Kashan, Iran, in 2020. All had full postoperative consciousness, no history of allergic reactions to peppermint, no respiratory comorbidity, and no cognitive problems.

Mean ages were 61 in the intervention group (which was 44% female) and 58 in the placebo group (which was 56% female). Cardiac surgeries included coronary artery bypass grafts (50 of 64 patients), heart valve surgery, and congenital heart defect surgery.

The intervention group received seven phases of peppermint essential oil aromatherapy three times a day until the end of the second day after surgery. Following surgery and 30 minutes before tracheal extubation, 0.1 mL of 10% peppermint essential oil plus 10 mL distilled water were infused into the nebulizer of a ventilator and delivered for 10 minutes. Subsequent phases of peppermint essence were delivered via nebulizer mask. Placebo group patients received 10 mL of distilled water instead of peppermint oil.

Researchers used the St. Mary's Hospital Sleep Questionnaire, which contains 14 questions on a 4-point Likert scale, to assess sleep quality. Patients in the intervention group received fewer morphine ampoules after surgery than the placebo group (P=0.001), but the number of propofol ampoules, thiopental ampoules, pethidine ampoules, and fentanyl citrate ampoules did not differ significantly between groups.

The study relied on self-reported sleep outcomes instead of objective measures and was limited by its small sample size. The researchers also acknowledged that light, noise, and other environmental factors may have influenced sleep quality, although attempts were made to control these variables.

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