Ask an answerable question (PICO)：
When a patient learns that surgery is required, regardless of the type or duration of the surgery, the patient can be seen to feel non-specific threats, resulting in an increase in anxiety and negative emotions. Preoperative anxiety is a type of uncomfortable mental state, and high levels of anxiety affect the postoperative recovery results. Lavender oil has the effect of stabilizing the inner mind. In clinical settings, a patient once asked whether they could inhale lavender oil while waiting for surgery, which aroused the motivation of the author. By reviewing literature, the author determined whether inhaling lavender oil can reduce the anxiety in preoperative patients, thereby providing evidence-based references for healthcare personnel.
The Method and Analysis of Literature Review：
A PICO (which stands for patient/population, intervention, comparison, and outcomes) question was established using empirical steps: Does inhaling lavender oil reduce anxiety in preoperative patients? Keywords, synonyms, MeSH terms, and word truncation were used to conduct literature search of 7 English and Chinese electronic databases (i.e., PubMed, Cochrane Library, CINAHL, Embase, Scopus, Airiti Library, and National Digital Library of Theses and Dissertations in Taiwan). The deadline of the literature search was September 25, 2023. Initially, 129 literature was obtained. Finally, abstracts and body texts were reviewed to select literature that met inclusion criteria. Three randomized controlled trials were included for analysis.
Critical Appraisal：
The Critical Appraisal Skill Programme 2020 was used for analyzing randomized controlled trial literature. The results showed that 90.9% of the appraisal items were assigned “Yes”. The literature received Level 2 rating from the 2011 Oxford CEBM Levels of Evidence. Results from meta-analysis with RevMan 5.4 software indicated that inhaling lavender oil was effective in reducing anxiety in preoperative patients (SMD = -0.34，95%CI [-0.62, -0.07]，P = 0.01). Although there is homogeneity between the two studies, more randomized controlled trials (larger sample size) are needed to confirm the efficacy of lavender oil in reducing anxiety levels prior to surgery.
Results, Conclusions and Recommendations：
The results of this systematic literature review show that patients can inhale lavender oil for 20 minutes in the form of aroma patches or by dripping the oil onto the gauze before surgery. The patients’ anxiety can thus be reduced. It is still necessary to consider individual patients when using it (i.e., allergies, pregnant women, infants etc.). Due to the lack of relevant research in Taiwan, relevant effect of lavender essential oil must be further confirmed through clinical empirical research, providing a reference for future practical application by clinical medical personnel and improvement of patient comfort before surgery.
