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A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients
Journal of PeriAnesthesia Nursing xxx (xxxx) xxx
Contents lists available at ScienceDirect
Journal of PeriAnesthesia Nursing journal homepage: www.jopan.org
Research
A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients Philip Francis Stanley, MD, MBA, FACS *, Lai Foon Wan, RN, Rostihar Abdul Karim, RN Department of Ophthalmology and Visual Sciences, Khoo Teck Puat Hospital, Singapore
a b s t r a c t Keywords: cataract surgery aromatherapy anxiety
Purpose: To determine if lavender aromatherapy can reduce preoperative anxiety in cataract surgery patients. Design: Single-center prospective randomized placebo-controlled trial. Methods: Seventy-five patients awaiting cataract surgery were randomized to lavender essential oil or grape seed oil (control) and administered the State-Trait Anxiety Inventory. Vital signs were also recorded. Findings: Patients in the lavender group showed greater improvements in self-reported anxiety using the State-Trait Anxiety Inventory (P ¼ .023, two-sample t test). Compared with the control group, the effects of lavender on the reduction of anxiety were statistically significant when adjusting for age, gender, and baseline scores (P ¼ .012, analysis of covariance). Conclusions: Lavender aromatherapy reduced anxiety in preoperative cataract surgery patients. © 2019 American Society of PeriAnesthesia Nurses. Published by Elsevier, Inc. All rights reserved.
When facing cataract surgery, patients can understandably be anxious. Fear of their vision not completely recovering, complications, the operation itself, the operation failing, and becoming blind are concerns in the preoperative period.1 Lavender is a traditional herb used for its analgesic, relaxing, antibacterial, and antifungal properties.2 It has been studied for anxiety reduction in patients with cancer, abdominal surgery, coronary artery angiography, and menstrual cramps.3 Lavender essential oil has been granted safe status by the US Food and Drug Administration, is well tolerated, and often applied topically or administered orally in an undiluted form.4 Lavender oil has a low incidence of irritation with the most common adverse effect being dermatitis.5 In aromatherapy, a vaporizer evaporates the lavender essential oil, and when inhaled, it enters the systemic circulation. The lavender plant contains linalool and linalyl acetate. Linalyl acetate is recognized as a narcotic, whereas linalool acts as a sedative.6 The
Conflict of interest: None to report. * Address correspondence to Philip Francis Stanley, Khoo Teck Puat Hospital, Department of Ophthalmology and Visual Sciences, 90 Yishun Central, Singapore 768828. E-mail address: [email protected] (P.F. Stanley).
mechanism of action of lavender oil centrally seems to be related to inhibition of voltage-gated calcium and sodium channels and interaction with N-methyl-D-aspartate or g-aminobutyric acid receptors.6 The mechanism of action of lavender oil peripherally is demonstrated as increased parasympathetic activity and decreased hemodynamic parameters in rats, dogs, and humans.4 Secondary to its effects on sympathetic nerve activity, lavender aromatherapy effectively reduced blood pressure and heart rate in patients admitted to the open heart surgery intensive care unit.7 A study of 150 preoperative patients showed lower anxiety during operating room transfer when lavender was sniffed and topically applied compared with sham or standard care.8 Lavender aromatherapy can reduce the levels of anxiety and plasma cortisol levels in open heart surgery patients before surgery.3 Lavender aromatherapy lowered sympathetic nervous system activity in patients with essential hypertension as demonstrated by a decrease in systolic blood pressure (SBP) and improved heart rate variability.9 Another study showed that inhaled lavender essential oil decreased stress and the pain level during needle insertion preoperatively.10 Critics of aromatherapy cite that systemic reviews had a high risk of bias, small sample sizes, and inadequate controls.11
https://doi.org/10.1016/j.jopan.2019.12.004 1089-9472/© 2019 American Society of PeriAnesthesia Nurses. Published by Elsevier, Inc. All rights reserved.
Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004
2
Stanley et al. / Journal of PeriAnesthesia Nursing xxx (xxxx) xxx
Table 1 Summary of Baseline Characteristics of the Study Population Total (n ¼ 75) Agey Gender, n (%) Malez Femalez SBP (mm Hg)y DBP (mm Hg)y Pulse (beat/min)y Respirations (breathes/min)y Baseline STAIy
Lavender (n ¼ 39)
62.4 (7.4) 33 42 141.5 81.2 76.6 18.3 39x
61.6 (7.0)
(44) (56) (18.3) (10.5) (11.9) (3.3) (10.3)
17 22 141.4 81.8 76.8 18.4 38.4
(44) (56) (18.7) (11.4) (12.2) (3.6) (10.8)
Control (n ¼ 36)
P*
63.25 (7.7) 16 20 141.6 80.6 76.3 18.1 39.6
(44) (56) (18.1) (9.6) (11.8) (3.1) (9.4)
.222 1 .719 .522 .873 .757 .617
SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant difference between groups. y Data are presented as mean and SD; two-sample t test was used. z Data are presented as number and percent; c2 test was used. x Moderate anxiety.
We hypothesized that the use of lavender aromatherapy before cataract surgery would reduce preoperative anxiety as assessed by the Speilberger State-Trait Anxiety Inventory (STAI) questionnaire. Blood pressure, pulse, and respiratory rate were also used to assess sympathetic activity. Patients and Methods Seventy-five patients scheduled for cataract surgery between January 10, 2017 and December 17, 2018 were randomized into a lavender aromatherapy group or control group. Randomization was ongoing as patients were recruited (subject 1 would be lavender group, subject 2 would be control group, with odd numbers assigned to lavender and even numbers assigned to control). Informed consent was obtained from all participants, and the study was reviewed and approved by the National Healthcare Group Domain Specific Review Board. Inclusion criteria were aged between 21 and 75 years, and subjects were excluded if they had a history of mental illness, used sedatives, and could not read and write English. Asthma, chronic obstructive pulmonary disease, or bronchitis, contact dermatitis and allergies to cosmetic fragrances, liver or kidney disorders, and significant laboratory abnormalities were other exclusion criteria. Procedure After registration in the day surgery operating theater, study patients were administered the STAI and vital signs were taken. Table 2 Comparison of the Mean Changes in Anxiety Scores and Vital Signs Between Lavender and Control (n ¼ 75) Mean Change From Baseline
Lavender
Control
Mean (SD)
Mean (SD)
SBP change DBP change Pulse change Respirations change STAI change
6.9 2.3 7.1 1.3 4.5
4.1 2.7 5.1 0.4 0.8
(13.5) (11.7) (9.9) (2.3) (8.0)
(12.2) (9.1) (7.8) (2.0) (5.9)
P*
Effect Sizey
.35 .87 .35 .08 .023z
0.218 0.039 0.218 0.409 0.517
NOTE. Bold text indicates statistical significance. SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 represents a statistical difference between groups. y Cohen's d where a commonly used interpretation is to refer to effect sizes as small (d ¼ 0.2), medium (d ¼ 0.5), and large (d ¼ 0.8) based on benchmarks suggested by Cohen. z Two-sample t test was used.
In the preoperative area, patients were exposed to lavender essential oil or grape seed oil (control) for 20 minutes. Subjects then took the STAI again and vital signs were taken. After this, they were brought to the operating room and underwent cataract surgery. In the lavender group, 20 drops of lavender aromatherapy containing lavender essential oil were placed in the aromatherapy vaporizer near the patient's chair in the lounge holding area. The aromatherapy electric oil vaporizer was from Australia and is approved by the Australian government. Two separate vaporizers were used to avoid any hint of aromatherapy in the control group. The lavender oil was steam distilled from the flowers of Lavandula officinalis. It was purity tested/quality assured and certified organic by Quality Assurance International. For a control patient (on a different day to avoid any hint of aromatherapy), the second vaporizer was used with 20 drops of grape seed oil. In each case, the patient was asked to breathe normally for 20 minutes, and then vital signs and the STAI were repeated. The STAI takes less than 5 minutes to complete and can be scored in less than 2 minutes.12 There are 20 questions where people rate their anxiety from one (not at all) to four (very much so), and scores range from 20 to 80. For example, low anxiety is 20 to 37, moderate anxiety is 38 to 44, and high anxiety is 45 to 80. The STAI has an overall median alpha coefficient of 0.92 in normative samples and slightly higher (0.92 to 0.94) when given under conditions of psychological stress. Psychologists, anesthesiologists, and allied health investigators use it as the gold standard in measuring anxiety.13
Statistical Analysis If the true difference in the lavender and control effect size is 0.74, we needed to study at least 29 experimental subjects and 28 control subjects to be able to reject the null hypothesis that the population means of the experimental and control groups are equal with a power of 0.8. This estimate was calculated using an unpaired two-tailed t test assuming a significance level of 0.05. With 39 experimental subjects and 36 control subjects recruited, the power increased to 0.87. Descriptive statistics were used to express baseline characteristics of the participants for the lavender group and control group. Continuous variables were summarized into mean and SD, and the two-sample t test was used. The categorical variable of gender was summarized into count and percentage, and the c2 test was used (Table 1). Differences between the lavender and control groups at baseline were compared using the two-sample t test (Table 2). The
Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004
Stanley et al. / Journal of PeriAnesthesia Nursing xxx (xxxx) xxx
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Table 3 Comparison of the Mean Changes in Anxiety Scores and Vital Signs at Baseline and After Lavender (n ¼ 39) Mean Change From Baseline
SBP (mm Hg) DBP (mm Hg) Pulse (beats/min) Respirations (breathes/min) STAI
P*
Baseline
After Lavender
Delta
Mean (SD)
Mean (SD)
Mean (SD)
141.38 81.8 76.8 18.4 38.4
134.5 79.3 69.1 17.1 33.9
6.9 2.5 7.8 1.3 4.5
(18.7) (11.4) (12.2) (3.6) (10.8)
(22.1) (11.8) (11.3) (3.2) (10.5)
(13.5) (11.7) (9.3) (2.3) (8.0)
.003 .200 <.001 .001 .001
NOTE. Bold text indicates statistical significance. SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant change from baseline; paired sample t test was used (two-tailed).
effect size was measured using Cohen's d and interpreted as small (d ¼ 0.2), medium (d ¼ 0.5), and large (d ¼ 0.8). Within the lavender group (Table 3) and control group (Table 4), the paired t test was used to compare mean STAI and vital signs at baseline and after the experiment. Finally, STAI scores and vital signs between the lavender and control groups were compared while adjusting for age, gender, and baseline scores using analysis of covariance (Table 5). The two-tailed analysis was considered significant at P < .05. Results The two groups were lavender essential oil (n ¼ 39) and control (n ¼ 36), for a total of n ¼ 75 (Table 1). The two groups were comprised of 56% females and had similar baseline characteristics that included moderate anxiety and vital signs (P > .05) (Table 1). The mean change in the STAI score was 4.5 in the lavender group and 0.8 in the control group, which was statistically significant (P ¼ .023, two-sample t test). Coincident with this decrease in anxiety, all the vital signs improved except for diastolic blood pressure (DBP). The mean SBP change was 6.9 mm Hg in the lavender group and 4.1 mm Hg in the control group. The mean DBP change was 2.3 mm Hg in the lavender group and 2.7 mm Hg in the control group. The mean change in pulse was 7.1 beats per minute in the lavender group and 5.1 beats per minute in the control group. The mean change in respirations was 1.3 breaths per minute in the lavender group and 0.4 breaths per minute in the control group. These vital sign differences did not reach statistical significance (Table 2). In the lavender group, the mean SBP decrease was 6.9 mm Hg from baseline. The mean DBP decrease was 2.5 mm Hg. The mean pulse change was 7.8 beats per minute. The mean respiration change was 1.3 breaths per minute. The mean STAI score change was 4.5. All these changes were statistically significant (P ¼ .003 for SBP, P < .001 for pulse, P ¼ .001 for respirations and STAI, all using paired sample t test) except the DBP (P ¼ .2, using paired sample t test) (Table 3). Examining the control group compared with its baseline, the mean SBP decrease Table 4 Comparison of the Mean Changes in Anxiety Scores and Vital Signs at Baseline and After Control (n ¼ 36) Mean Change From Baseline
SBP (mm Hg) DBP (mm Hg) Pulse (beats/min) Respirations (breathes/min) STAI
Baseline
After Control
Delta
Mean (SD)
Mean (SD)
Mean (SD)
141.6 80.6 76.3 18.1 39.6
137.6 77.9 70.9 17.7 38.8
4.1 2.6 5.4 0.4 0.8
(18.1) (9.6) (11.8) (3.1) (9.8)
(18.8) (9.7) (12.0) (2.9) (10.9)
(12.3) (9.1) (7.5) (2.0) (5.9)
P*
was 4.1 mm Hg. The mean DBP decrease was 2.6 mm Hg. The mean pulse change was 5.4 beats per minute. The mean respiration change was 0.4 breaths per minute. The mean STAI score change was 0.8. None of these changes were statistically significant except for heart rate (P < .001 using paired sample t test) (Table 4). Compared with the control group when adjusting for age, gender, and baseline scores, the effects of lavender on the STAI score (coefficient of 3.9) were statistically significant (P ¼ .012 using analysis of covariance), whereas changes in SBP, DBP, heart rate, and respirations did not reach statistical significance (Table 5). The effect size comparing lavender and control was medium for STAI (0.517) and small for SBP (0.218) and DBP (0.039), respirations (0.409), and pulse (0.218) (Table 2). There were no adverse effects in either the lavender or the grape seed oil groups. Discussion This is the first randomized placebo-controlled study on aromatherapy for preoperative anxiety reduction in cataract surgery patients we are aware of. This study has several limitations. The first is that the lavender aromatherapy and grape seed oil are odors that both the investigator and study subjects can detect. Therefore, it cannot be a truly double-blind study. The second limitation is the potency and delivery of the aromatherapy. We chose a heated vaporizer with 20 drops of essential oil or control, whereas other studies have used ultrasound diffusers commonly used in health spas.12 Still other studies have used a cloth infused with aromatherapy for direct inhalation.2 As a result, it is hard to assess the optimum delivery system and dose until further studies are done. Conclusion Lavender is an inexpensive, well-tolerated,4 and easy intervention to lower anxiety in patients getting ready for cataract surgery.
Table 5 ANCOVA for Comparing the Control Group With the Lavender Group on Score Changes in Anxiety and Vital Signs While Adjusting for Age, Gender, and Baseline Scores (n ¼ 75) Outcome
.053 .092 <.001 .26 .44
NOTE. Bold text indicates statistical significance. SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant change from baseline; paired sample t test was used (two-tailed).
Score Score Score Score Score
change change change change change
in in in in in
SBP DBP pulse respirations STAI
Coefficient
95% CI
P*
2.7 1.1 2.1 0.8 3.9y
8.3, 3.3, 5.8, 1.7, 6.9,
.35 .63 .27 .056 .012
2.9 5.4 1.6 0.02 0.9
NOTE. Bold text indicates statistical significance. ANCOVA, analysis of covariance; 95% CI, 95% confidence interval; SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant change from baseline. y Lavender significantly reduced the STAI score 3.9 more than control.
Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004
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Stanley et al. / Journal of PeriAnesthesia Nursing xxx (xxxx) xxx
References 1. Ramirez D, Brodie F, Rose-Nussbaumer J, Ramanathan S. Anxiety in patients undergoing cataract surgery: A pre- and postoperative comparison. Clin Ophthalmol. 2017;11:1979e1986. 2. Fayazi S, Babashahi M, Rezaei M. The effect of inhalation aromatherapy on anxiety level of the patients in preoperative period. Iran J Nurs Midwifery Res. 2011;16:278e283. 3. Hosseini S, Heydari A, Vakili M, Moghadam S, Tazyky S. Effect of lavender essence inhalation on the level of anxiety and blood cortisol in candidates for open-heart surgery. Iran J Nurs Midwifery Res. 2016;21:397e401. 4. Malcolm BJ, Tallian K. Essential oil of lavender in anxiety disorders: Ready for prime time? Ment Health Clin. 2017;7:147e155. 5. Stea S, Beraudi A, DePasquale D. Essential oils for complementary treatment of surgical patients: State of the art. Evid Based Complement Alternat Med. 2014;2014, 726341. 6. Wotman M, Levinger J, Leung L, Kallush A, Mauer E, Kacker A. The efficacy of lavender aromatherapy in reducing preoperative anxiety in ambulatory
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surgery patients undergoing procedures in general otolaryngology. Laryngoscope Invest Otolaryngol. 2017;2:437e441. Salamati A, Mashouf S, Mojab F. Effect of inhalation of lavender essential oil on vital signs in open heart surgery ICU. Iran J Pharm Res. 2017;16:404e409. Braden R, Reichow S, Halm M. The use of the essential oil lavandin to reduce preoperative anxiety in surgical patients. J Perianesth Nurs. 2009;24:348e355. Cha JH, Lee SH, Yoo YS. Effects of aromatherapy on changes in the autonomic nervous system, aortic pulse wave velocity and aortic augmentation index in patients with essential hypertension. J Korean Acad Nurs. 2010;40:705e713. Kim S, Kim H-J, Yeo J-S, Hong S-J, Lee J-M, Jeon Y. The effect of lavender oil on stress, bispectral index values, and needle insertion pain in volunteers. J Altern Complement Med. 2011;17:823e826. Lee MS, Choi J, Posadzki P, Ernst E. Aromatherapy for health care: An overview of systematic reviews. Maturitas. 2012;71:257e260. Ni CH, Hou WH, Kao CC, et al. The anxiolytic effect of aromatherapy on patients awaiting ambulatory surgery: A randomized controlled trial. Evid Based Complement Altern Med. 2013;2013, 927419. Muzzarelli L, Force M, Sebold M. Aromatherapy and reducing pre-procedural anxiety: A controlled prospective study. Gastroenterol Nurs. 2006;29:466e471.
Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004
Contents lists available at ScienceDirect
Journal of PeriAnesthesia Nursing journal homepage: www.jopan.org
Research
A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients Philip Francis Stanley, MD, MBA, FACS *, Lai Foon Wan, RN, Rostihar Abdul Karim, RN Department of Ophthalmology and Visual Sciences, Khoo Teck Puat Hospital, Singapore
a b s t r a c t Keywords: cataract surgery aromatherapy anxiety
Purpose: To determine if lavender aromatherapy can reduce preoperative anxiety in cataract surgery patients. Design: Single-center prospective randomized placebo-controlled trial. Methods: Seventy-five patients awaiting cataract surgery were randomized to lavender essential oil or grape seed oil (control) and administered the State-Trait Anxiety Inventory. Vital signs were also recorded. Findings: Patients in the lavender group showed greater improvements in self-reported anxiety using the State-Trait Anxiety Inventory (P ¼ .023, two-sample t test). Compared with the control group, the effects of lavender on the reduction of anxiety were statistically significant when adjusting for age, gender, and baseline scores (P ¼ .012, analysis of covariance). Conclusions: Lavender aromatherapy reduced anxiety in preoperative cataract surgery patients. © 2019 American Society of PeriAnesthesia Nurses. Published by Elsevier, Inc. All rights reserved.
When facing cataract surgery, patients can understandably be anxious. Fear of their vision not completely recovering, complications, the operation itself, the operation failing, and becoming blind are concerns in the preoperative period.1 Lavender is a traditional herb used for its analgesic, relaxing, antibacterial, and antifungal properties.2 It has been studied for anxiety reduction in patients with cancer, abdominal surgery, coronary artery angiography, and menstrual cramps.3 Lavender essential oil has been granted safe status by the US Food and Drug Administration, is well tolerated, and often applied topically or administered orally in an undiluted form.4 Lavender oil has a low incidence of irritation with the most common adverse effect being dermatitis.5 In aromatherapy, a vaporizer evaporates the lavender essential oil, and when inhaled, it enters the systemic circulation. The lavender plant contains linalool and linalyl acetate. Linalyl acetate is recognized as a narcotic, whereas linalool acts as a sedative.6 The
Conflict of interest: None to report. * Address correspondence to Philip Francis Stanley, Khoo Teck Puat Hospital, Department of Ophthalmology and Visual Sciences, 90 Yishun Central, Singapore 768828. E-mail address: [email protected] (P.F. Stanley).
mechanism of action of lavender oil centrally seems to be related to inhibition of voltage-gated calcium and sodium channels and interaction with N-methyl-D-aspartate or g-aminobutyric acid receptors.6 The mechanism of action of lavender oil peripherally is demonstrated as increased parasympathetic activity and decreased hemodynamic parameters in rats, dogs, and humans.4 Secondary to its effects on sympathetic nerve activity, lavender aromatherapy effectively reduced blood pressure and heart rate in patients admitted to the open heart surgery intensive care unit.7 A study of 150 preoperative patients showed lower anxiety during operating room transfer when lavender was sniffed and topically applied compared with sham or standard care.8 Lavender aromatherapy can reduce the levels of anxiety and plasma cortisol levels in open heart surgery patients before surgery.3 Lavender aromatherapy lowered sympathetic nervous system activity in patients with essential hypertension as demonstrated by a decrease in systolic blood pressure (SBP) and improved heart rate variability.9 Another study showed that inhaled lavender essential oil decreased stress and the pain level during needle insertion preoperatively.10 Critics of aromatherapy cite that systemic reviews had a high risk of bias, small sample sizes, and inadequate controls.11
https://doi.org/10.1016/j.jopan.2019.12.004 1089-9472/© 2019 American Society of PeriAnesthesia Nurses. Published by Elsevier, Inc. All rights reserved.
Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004
2
Stanley et al. / Journal of PeriAnesthesia Nursing xxx (xxxx) xxx
Table 1 Summary of Baseline Characteristics of the Study Population Total (n ¼ 75) Agey Gender, n (%) Malez Femalez SBP (mm Hg)y DBP (mm Hg)y Pulse (beat/min)y Respirations (breathes/min)y Baseline STAIy
Lavender (n ¼ 39)
62.4 (7.4) 33 42 141.5 81.2 76.6 18.3 39x
61.6 (7.0)
(44) (56) (18.3) (10.5) (11.9) (3.3) (10.3)
17 22 141.4 81.8 76.8 18.4 38.4
(44) (56) (18.7) (11.4) (12.2) (3.6) (10.8)
Control (n ¼ 36)
P*
63.25 (7.7) 16 20 141.6 80.6 76.3 18.1 39.6
(44) (56) (18.1) (9.6) (11.8) (3.1) (9.4)
.222 1 .719 .522 .873 .757 .617
SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant difference between groups. y Data are presented as mean and SD; two-sample t test was used. z Data are presented as number and percent; c2 test was used. x Moderate anxiety.
We hypothesized that the use of lavender aromatherapy before cataract surgery would reduce preoperative anxiety as assessed by the Speilberger State-Trait Anxiety Inventory (STAI) questionnaire. Blood pressure, pulse, and respiratory rate were also used to assess sympathetic activity. Patients and Methods Seventy-five patients scheduled for cataract surgery between January 10, 2017 and December 17, 2018 were randomized into a lavender aromatherapy group or control group. Randomization was ongoing as patients were recruited (subject 1 would be lavender group, subject 2 would be control group, with odd numbers assigned to lavender and even numbers assigned to control). Informed consent was obtained from all participants, and the study was reviewed and approved by the National Healthcare Group Domain Specific Review Board. Inclusion criteria were aged between 21 and 75 years, and subjects were excluded if they had a history of mental illness, used sedatives, and could not read and write English. Asthma, chronic obstructive pulmonary disease, or bronchitis, contact dermatitis and allergies to cosmetic fragrances, liver or kidney disorders, and significant laboratory abnormalities were other exclusion criteria. Procedure After registration in the day surgery operating theater, study patients were administered the STAI and vital signs were taken. Table 2 Comparison of the Mean Changes in Anxiety Scores and Vital Signs Between Lavender and Control (n ¼ 75) Mean Change From Baseline
Lavender
Control
Mean (SD)
Mean (SD)
SBP change DBP change Pulse change Respirations change STAI change
6.9 2.3 7.1 1.3 4.5
4.1 2.7 5.1 0.4 0.8
(13.5) (11.7) (9.9) (2.3) (8.0)
(12.2) (9.1) (7.8) (2.0) (5.9)
P*
Effect Sizey
.35 .87 .35 .08 .023z
0.218 0.039 0.218 0.409 0.517
NOTE. Bold text indicates statistical significance. SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 represents a statistical difference between groups. y Cohen's d where a commonly used interpretation is to refer to effect sizes as small (d ¼ 0.2), medium (d ¼ 0.5), and large (d ¼ 0.8) based on benchmarks suggested by Cohen. z Two-sample t test was used.
In the preoperative area, patients were exposed to lavender essential oil or grape seed oil (control) for 20 minutes. Subjects then took the STAI again and vital signs were taken. After this, they were brought to the operating room and underwent cataract surgery. In the lavender group, 20 drops of lavender aromatherapy containing lavender essential oil were placed in the aromatherapy vaporizer near the patient's chair in the lounge holding area. The aromatherapy electric oil vaporizer was from Australia and is approved by the Australian government. Two separate vaporizers were used to avoid any hint of aromatherapy in the control group. The lavender oil was steam distilled from the flowers of Lavandula officinalis. It was purity tested/quality assured and certified organic by Quality Assurance International. For a control patient (on a different day to avoid any hint of aromatherapy), the second vaporizer was used with 20 drops of grape seed oil. In each case, the patient was asked to breathe normally for 20 minutes, and then vital signs and the STAI were repeated. The STAI takes less than 5 minutes to complete and can be scored in less than 2 minutes.12 There are 20 questions where people rate their anxiety from one (not at all) to four (very much so), and scores range from 20 to 80. For example, low anxiety is 20 to 37, moderate anxiety is 38 to 44, and high anxiety is 45 to 80. The STAI has an overall median alpha coefficient of 0.92 in normative samples and slightly higher (0.92 to 0.94) when given under conditions of psychological stress. Psychologists, anesthesiologists, and allied health investigators use it as the gold standard in measuring anxiety.13
Statistical Analysis If the true difference in the lavender and control effect size is 0.74, we needed to study at least 29 experimental subjects and 28 control subjects to be able to reject the null hypothesis that the population means of the experimental and control groups are equal with a power of 0.8. This estimate was calculated using an unpaired two-tailed t test assuming a significance level of 0.05. With 39 experimental subjects and 36 control subjects recruited, the power increased to 0.87. Descriptive statistics were used to express baseline characteristics of the participants for the lavender group and control group. Continuous variables were summarized into mean and SD, and the two-sample t test was used. The categorical variable of gender was summarized into count and percentage, and the c2 test was used (Table 1). Differences between the lavender and control groups at baseline were compared using the two-sample t test (Table 2). The
Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004
Stanley et al. / Journal of PeriAnesthesia Nursing xxx (xxxx) xxx
3
Table 3 Comparison of the Mean Changes in Anxiety Scores and Vital Signs at Baseline and After Lavender (n ¼ 39) Mean Change From Baseline
SBP (mm Hg) DBP (mm Hg) Pulse (beats/min) Respirations (breathes/min) STAI
P*
Baseline
After Lavender
Delta
Mean (SD)
Mean (SD)
Mean (SD)
141.38 81.8 76.8 18.4 38.4
134.5 79.3 69.1 17.1 33.9
6.9 2.5 7.8 1.3 4.5
(18.7) (11.4) (12.2) (3.6) (10.8)
(22.1) (11.8) (11.3) (3.2) (10.5)
(13.5) (11.7) (9.3) (2.3) (8.0)
.003 .200 <.001 .001 .001
NOTE. Bold text indicates statistical significance. SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant change from baseline; paired sample t test was used (two-tailed).
effect size was measured using Cohen's d and interpreted as small (d ¼ 0.2), medium (d ¼ 0.5), and large (d ¼ 0.8). Within the lavender group (Table 3) and control group (Table 4), the paired t test was used to compare mean STAI and vital signs at baseline and after the experiment. Finally, STAI scores and vital signs between the lavender and control groups were compared while adjusting for age, gender, and baseline scores using analysis of covariance (Table 5). The two-tailed analysis was considered significant at P < .05. Results The two groups were lavender essential oil (n ¼ 39) and control (n ¼ 36), for a total of n ¼ 75 (Table 1). The two groups were comprised of 56% females and had similar baseline characteristics that included moderate anxiety and vital signs (P > .05) (Table 1). The mean change in the STAI score was 4.5 in the lavender group and 0.8 in the control group, which was statistically significant (P ¼ .023, two-sample t test). Coincident with this decrease in anxiety, all the vital signs improved except for diastolic blood pressure (DBP). The mean SBP change was 6.9 mm Hg in the lavender group and 4.1 mm Hg in the control group. The mean DBP change was 2.3 mm Hg in the lavender group and 2.7 mm Hg in the control group. The mean change in pulse was 7.1 beats per minute in the lavender group and 5.1 beats per minute in the control group. The mean change in respirations was 1.3 breaths per minute in the lavender group and 0.4 breaths per minute in the control group. These vital sign differences did not reach statistical significance (Table 2). In the lavender group, the mean SBP decrease was 6.9 mm Hg from baseline. The mean DBP decrease was 2.5 mm Hg. The mean pulse change was 7.8 beats per minute. The mean respiration change was 1.3 breaths per minute. The mean STAI score change was 4.5. All these changes were statistically significant (P ¼ .003 for SBP, P < .001 for pulse, P ¼ .001 for respirations and STAI, all using paired sample t test) except the DBP (P ¼ .2, using paired sample t test) (Table 3). Examining the control group compared with its baseline, the mean SBP decrease Table 4 Comparison of the Mean Changes in Anxiety Scores and Vital Signs at Baseline and After Control (n ¼ 36) Mean Change From Baseline
SBP (mm Hg) DBP (mm Hg) Pulse (beats/min) Respirations (breathes/min) STAI
Baseline
After Control
Delta
Mean (SD)
Mean (SD)
Mean (SD)
141.6 80.6 76.3 18.1 39.6
137.6 77.9 70.9 17.7 38.8
4.1 2.6 5.4 0.4 0.8
(18.1) (9.6) (11.8) (3.1) (9.8)
(18.8) (9.7) (12.0) (2.9) (10.9)
(12.3) (9.1) (7.5) (2.0) (5.9)
P*
was 4.1 mm Hg. The mean DBP decrease was 2.6 mm Hg. The mean pulse change was 5.4 beats per minute. The mean respiration change was 0.4 breaths per minute. The mean STAI score change was 0.8. None of these changes were statistically significant except for heart rate (P < .001 using paired sample t test) (Table 4). Compared with the control group when adjusting for age, gender, and baseline scores, the effects of lavender on the STAI score (coefficient of 3.9) were statistically significant (P ¼ .012 using analysis of covariance), whereas changes in SBP, DBP, heart rate, and respirations did not reach statistical significance (Table 5). The effect size comparing lavender and control was medium for STAI (0.517) and small for SBP (0.218) and DBP (0.039), respirations (0.409), and pulse (0.218) (Table 2). There were no adverse effects in either the lavender or the grape seed oil groups. Discussion This is the first randomized placebo-controlled study on aromatherapy for preoperative anxiety reduction in cataract surgery patients we are aware of. This study has several limitations. The first is that the lavender aromatherapy and grape seed oil are odors that both the investigator and study subjects can detect. Therefore, it cannot be a truly double-blind study. The second limitation is the potency and delivery of the aromatherapy. We chose a heated vaporizer with 20 drops of essential oil or control, whereas other studies have used ultrasound diffusers commonly used in health spas.12 Still other studies have used a cloth infused with aromatherapy for direct inhalation.2 As a result, it is hard to assess the optimum delivery system and dose until further studies are done. Conclusion Lavender is an inexpensive, well-tolerated,4 and easy intervention to lower anxiety in patients getting ready for cataract surgery.
Table 5 ANCOVA for Comparing the Control Group With the Lavender Group on Score Changes in Anxiety and Vital Signs While Adjusting for Age, Gender, and Baseline Scores (n ¼ 75) Outcome
.053 .092 <.001 .26 .44
NOTE. Bold text indicates statistical significance. SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant change from baseline; paired sample t test was used (two-tailed).
Score Score Score Score Score
change change change change change
in in in in in
SBP DBP pulse respirations STAI
Coefficient
95% CI
P*
2.7 1.1 2.1 0.8 3.9y
8.3, 3.3, 5.8, 1.7, 6.9,
.35 .63 .27 .056 .012
2.9 5.4 1.6 0.02 0.9
NOTE. Bold text indicates statistical significance. ANCOVA, analysis of covariance; 95% CI, 95% confidence interval; SBP, systolic blood pressure; DBP, diastolic blood pressure; STAI, State-Trait Anxiety Inventory. * P < .05 indicates a significant change from baseline. y Lavender significantly reduced the STAI score 3.9 more than control.
Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004
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Please cite this article as: Stanley PF et al., A Randomized Prospective Placebo-Controlled Study of the Effects of Lavender Aromatherapy on Preoperative Anxiety in Cataract Surgery Patients, Journal of PeriAnesthesia Nursing, https://doi.org/10.1016/j.jopan.2019.12.004