1. Journal of PeriAnesthesia Nursing
A Comparison of Aromatherapy to Standard Care for Relief of PONV and PDNV in Ambulatory Surgical Patients 
Lois M. Stallings-Welden, DNP, RN, CNS, Mary Doerner, MSN, RN, CPAN, CAPA, Elizabeth (Libby) Ketchem, MS, BSN, RN, CWS, NE- BC, Laura Benkert, BSN, RN, CAPA, Susan Alka, RN, Jonathan D. Stallings, PhD 
Journal of PeriAnesthesia Nursing 
DOI: /j.jopan
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions

2. Figure 1
Machine learning workflow. PONV, postoperative nausea and vomiting; PO, postoperative; BMI, body mass index.
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions

3. Figure 2
The total number of postoperative patients that experienced PONV was 64 (29%) of 221. The number of patients with postoperative nausea and vomiting (PONV) by group were 33 (52%) in the aromatherapy (AT) and 31 (48%) in the standard care (SC). This figure is available in color online at
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions

4. Figure 3
Patient responses to study questions on a six-point Likert scale, 0-5: (A) “The treatment I was given relieved my nausea in a timely manner,” and (B) “The treatment I received controlled my nausea.” Note: no patients responded with “Disagree.” AT, aromatherapy; SC, standard care. This figure is available in color online at
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions

5. Figure 4
(A) Improvement in PONV by study group AT (red) and SC (blue). The change in nausea was determined (eg, patient #1 entered PACU with a level of 4 nausea, and at the third assessment, patient #1 had a level of 1 nausea, resulting in an improvement of 3 in severity). The number of analgesic doses (B) and (C) antiemetics doses administered in patients that reported NV (YES) or did not report nausea (NO) was also determined. PONV, postoperative nausea and vomiting; AT, aromatherapy; SC, standard care; PACU, postanesthesia care unit. This figure is available in color online at
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
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6. Figure 5
Receiver operator curve (ROC). Sixty-five percent of the data set (training set) was randomly partitioned and resampled by (A) repeated cross-folds, (B) cross-folds, or (C) Bootstrap methods provided by caret.
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions

7. Figure 6
Area under the curve (AUC). Using the cross-folds resampling method to train and tune the model, it was then used to test the remaining 35% of the data set (testing set). AUC was used to assess the best performance. The testing was repeated five times, and performance show in the chart. Cforest performed the best, with the least variance. ROC, receiver operator curve.
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions

8. Figure 7
Area under the curve (AUC) for the cforest model. Based on our data set, literature-based factors provided modest predictive value using the cforest method (AUC ∼ 0.69).
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions

9. Figure 8
Relative variable importance of factors in PONV. Of the literature-based factors, gender provided the most predictive power. PONV, postoperative nausea and vomiting. This figure is available in color online at
Journal of PeriAnesthesia Nursing DOI: ( /j.jopan )
Copyright © 2016 American Society of PeriAnesthesia Nurses Terms and Conditions