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Postoperative nausea and vomiting

Efficacy of acupressure on quality of recovery after surgery

Randomised controlled trial

Noll, Eric; Shodhan, Shivam; Romeiser, Jamie L.; Madariaga, Maria C.; Page, Christopher; Santangelo, Diane; Guo, Xiaojun; Pryor, Aurora D.; Gan, Tong J.; Bennett-Guerrero, Elliott

Author Information
European Journal of Anaesthesiology: August 2019 - Volume 36 - Issue 8 - p 557-565
doi: 10.1097/EJA.0000000000001001
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Abstract

This Original Article accompanies the following invited commentary:

Diemunsch P, Kranke P. Acupressure and quality of recovery. Eur J Anaesthesiol 2019; 36:555–556.

Introduction

Numerous pharmaceutical,1 procedural2 and nutritional3 interventions have been explored to improve postoperative quality of recovery (QoR).4 Despite these efforts many patients continue to experience adverse postoperative events such as pain, postoperative nausea and vomiting (PONV), and poor sleep. This has led to exploration of complementary medicine interventions5 (e.g. acupoint stimulation), to see if they can improve patients’ experience. Acupoint stimulation has been associated with favourable effects on peri-operative symptoms such as nausea,6,7 pain5,8,9 and sleep disturbance10,11 and therefore could improve patient recovery.

Acupoint stimulation is postulated to modulate neurological signal transmission via afferent nociceptive pathways.12 Such stimulation can be triggered with needles (acupuncture), electric current (electro-acupuncture) or pressure (acupressure).13 Acupressure is a noninvasive approach to acupoint stimulation whereby the practitioner applies direct pressure on the acupoint.13–15 Acupressure has been suggested as a suitable alternative to needle-based acupuncture techniques, as it decreases the risks and discomfort associated with needle punctures. Alleviating peri-operative symptoms by using this kind of nonpharmaceutical treatment may improve patient health status, including the patient's perspective after surgery (also referred to as QoR16) without increasing the risk of drug-related adverse events.

Few well designed clinical trials have assessed acupoint stimulation therapy for postoperative recovery.17 Therefore, we undertook a three group, randomised clinical trial, to assess whether acupressure improves the QoR in patients postoperatively. We tested the hypothesis that acupressure is superior to sham treatment or no intervention with respect to improvement in postoperative QoR.

Methods

The study was approved by the Stony Brook University Institutional Review Board (# 867005-2). The protocol was registered at ClinicalTrials.gov (NCT02762435, principal investigator: Dr Elliott Bennett-Guerrero) on 14 April 2016 and the study methods were published in Trials journal.18

The study took place at Stony Brook Medicine University Hospital from 28 March 2016 to 3 October 2017. Written informed consent was obtained from all patients.

Inclusion criteria were English-speaking patients who were expected to stay in hospital for at least 2 days after surgery and who could provide written informed consent. Exclusion criteria were patients younger than 18 years of age; patients whose three acupressure points on the hand and wrist were not accessible due to skin breakdown, ulcers, cellulitis or broken bone; indwelling cannula within a 5-cm radius of the pressure points (since the plan was to apply the pressure unilaterally, this exclusion only applied if the access to any of the three acupoints was unavailable in both extremities); significant dementia or altered mental status that would preclude assessment of the QoR-15 survey; allergic reaction to ink from a permanent marker; stroke or other neurological condition which preclude full sensation in both upper extremities; use of regional anaesthesia (e.g. epidural, continuous peripheral nerve catheter) after postoperative day 1 at 12 noon; pregnant women. We amended the study protocol after initiating the study, before any statistical analyses were performed, to allow for the enrolment of patients who had a regional anaesthetic discontinued before postoperative day 1 at 12 noon as part of their routine care.

Randomisation and allocation concealment

Patients were randomly allocated by means of a sealed opaque envelope technique to one of the three experimental groups (acupressure therapy, sham-acupressure or no intervention) on postoperative day one (POD 1).

A 1 : 1 : 1 ratio computer-generated randomisation schema (SAS©, Cary, North Carolina, USA), stratified on the use of postoperative regional anaesthesia (through POD 1), in random blocks of varying sizes, was provided by the trial statistician (coauthor JR). To minimise potential bias by the statistician, the statistician provided the randomisation schemes in an A/B/C format; thereafter an independent individual not otherwise involved in the study finalised the correspondence between randomisation schemes and actual treatment group before sealing each envelope. To minimise bias in marking acupoints, patients were randomised (i.e. envelope opened) only after a research team member had marked the three acupoints with a permanent marker.

Outcome measures

Patients, routine care providers and team members performing outcome assessments were blind to a patient's group allocation. The data were recorded in an electronic case report form. The primary endpoint was the postoperative change in the QoR-15 score.16

The QoR-15 is a 15-question survey measuring a patient's QoR, including pain, nausea, sleep and well being. Each question is rated on a Likert scale from 0 to 10, with a maximum score of 150 points indicating ideal health status. The QoR-15 questionnaire was completed by a research team member, blind to the patient's group, at two time points: first, postoperative day 1 between 7:30 and 8:30 a.m. before the first acupressure or sham intervention, and second, postoperative day 3 between 7:00 and 10:00 a.m. If the patient was discharged from the hospital before study day 3, the QoR-15 survey was completed by telephone. Secondary endpoints included assessment of pain, nausea, vomiting and patient satisfaction, using numeric rating scales from 0 (totally unsatisfied) to 10 (totally satisfied), assessed at the same time as the QoR-15 survey was administered. Other secondary endpoints were recorded from the electronic medical record including antiemetic administration, opioid and nonopioid drugs consumption and hospital length of stay.

Intervention

Details of the intervention groups are reported in our previous study protocol publication.18 Briefly, there were three groups in the study: acupressure therapy, sham-acupressure therapy (i.e. extremely light pressure) and no intervention. Acupressure therapy was performed on the PC6, LI4 and HT7 acupoints (Fig. 1).18 PC6 was located on the anterior forearm, proximal to the wrist crease corresponding to a distance of two patient interphalangeal thumb widths between the flexor carpi radialis and palmaris longus, LI 4 at the centre between 1st and 2nd metacarpal bones and HT7 at the anterior wrist crease, lateral to the flexor carpi ulnaris tendon and proximal to the pisiform.18 In the sham group, light touch was performed at the same three acupoints. Active acupressure therapy or light touch was performed for 2 min on each acupoint three times per day during the hospital stay for a maximum of two days (postoperative days 1 and 2). No interventions were performed on patients in the third study group. Study team members were trained and tested on a simulator19 to apply a standardised force during the active acupressure (a target pressure between 4000 and 7000 g) and light touch interventions (target pressure between 6 and 80 g). This training consisted of 2-min simulation sessions aimed at reproducing the level of force applied by an expert in acupressure (coauthor XG). These sessions were repeated until all study members were categorised as proficient using the cumulative sum statistical approach.19

Fig. 1
Fig. 1:
Study acupoints locations. PC6, LI4 and HT7 acupoint locations. The acupoints are represented by the applied thumb position.

Peri-operative management

To maximise the generalisability of our study results we decided to use a pragmatic study design as previously published:18 all patients received routine care and clinicians involved in patient care were blind to the study group assignment.

Statistical methods

All statistical analyses were performed by a biostatistician (coauthor JR). As described in the study protocol publication,18 sample size calculations were carried out using SAS 9.4 software (SAS). Based on results from a study examining the psychometric properties of the QoR-15 evaluation,16,20 we estimated the overall change from baseline to follow-up in untreated patients would be approximately 5% of the instrument total, or +7.5 points. We powered the study to be able to detect a clinically relevant change of 10% (+15 points) in the treatment group, with a SD of 12 points. A sample size of 50 patients per group (150 total) was calculated based on a two-sample t test with power = 0.85 and alpha = 0.05. We enrolled 200 patients to allow for the loss of patients that inevitably occurs (e.g. cancelled surgery).

Analysis was as previously described.18 Briefly, the primary endpoint was the change in the QoR-15 score from the baseline on postoperative day 1 the score on day 3. The mean change in the score was normally distributed (Shapiro–Wilk P value >0.05), and did not violate the homogeneity of variance assumption (Levene's Test for homogeneity P value = 0.36). Therefore, differences between the three groups were assessed using an analysis of variance (ANOVA). Student's t tests were used to examine differences between the no-intervention group and the acupressure group. Multiple linear regression was used to control for any differences not addressed through the randomisation process. Secondary endpoints included individual measures of pain (0 to 10 scale), nausea (worst nausea since end of surgery/last assessment, 0 to 10 scale), occurrence of vomiting and opioid consumption. Opioid consumption was calculated as the average milligrams of a morphine equivalent dose per hour for each specified time-period [i.e. post anaesthesia care unit (PACU) time, end of PACU to randomisation, randomisation to midnight POD 1, POD 2 (midnight-to-midnight) and POD 3 (midnight-to-midnight)]. If patients were discharged prior to day 3, the last morphine equivalent dose was calculated based on their discharge time. Total milligrams of morphine equivalent from randomisation to POD3 morning (total time of the intervention) was also calculated. Finally, patient satisfaction was measured on POD 3. Baseline pre-operative, intra-operative and PACU characteristics were assessed for imbalance between the groups. Depending on the normality of their distribution and homogeneity of variance, outcomes were analysed using ANOVA or Kruskal–Wallis. Multiple linear regression was used to control for any differences not addressed through the randomisation process. All statistical analyses were performed using SAS 9.4, SAS.

Results

A total of 200 patients were enrolled: 37 were not randomised (Fig. 2). One patient was randomised but withdrew from the study immediately after randomisation, and one patient was randomised but withdrew after one treatment. A total of 161 patients were randomised, received treatments, and completed both baseline and follow-up assessments. There were 54 patients in the no-intervention group, 54 patients in the acupressure group and 53 patients in the sham-acupressure group (Fig. 2). All patients received the treatment to which they were randomised. For all 161 patients the QoR scores, pain scores and incidence of nausea/vomiting were collected at baseline and on postoperative day 3 – thus, no imputations for these variables were required.

Fig. 2
Fig. 2:
CONSORT flow diagram. Patient flow during the APPROVE trial. LOS, length of stay.

Peri-operative characteristics are reported in Tables 1 and 2. Most patients had orthopaedic procedures (67%), with a median surgery duration of 124 min. The study groups were generally well balanced. Only sleep apnoea was significantly imbalanced, with a smaller proportion of sleep apnoea patients in the control group. A trend towards imbalance was observed for history of PONV, alcohol consumption and American Society of Anesthesiologists (ASA) physical status: there was a marginally smaller proportion of PONV and alcohol use in the acupressure group, and marginally higher proportion of ASA IV patients in the sham group. The median number of treatments (possible maximum of six) were similar in the sham and acupressure groups [6 (5 to 6) and 6 (5 to 6), respectively]. Median postoperative length of stay was also similar in the control, sham and acupressure groups: 3 (2 to 4), 3 (2 to 4) and 3 (2 to 4), respectively.

Table 1
Table 1:
Pre-operative characteristics
Table 2
Table 2:
Intra-operative and post anaesthesia care unit characteristics

The primary endpoint results (QoR-15 score) are reported in Fig. 3. Postoperative mean change in QoR-15 between POD 1 and POD 3 was 15.2 (17.8) [95% confidence interval (CI), 10.4 to 20.1], 14.2 (21.9) (95% CI, 8.2 to 20.2) and 9.2 (21.7) (95% CI, 3.3 to 15.1) for the acupressure, sham, and no intervention groups respectively. Scores did not differ statistically (P = 0.27) between any of the three groups. There was also no statistically significant difference in the change of QoR-15 score between the no-intervention and acupressure groups (P = 0.12). After using a multiple linear regression to control for variables that showed a preintervention imbalance or trend towards imbalance between the groups, results did not change for the acupressure vs. no intervention groups, nor for the three-group comparison.

Fig. 3
Fig. 3:
Changes in Quality of Recovery-15. Shows mean (SD) Quality of Recovery-15 scores assessed on postoperative day 1 before randomisation and on postoperative day 3 in each study group. The blue line represents the no-intervention group, the red line the sham-intervention group and the green line the acupressure group. The P value for quality of recovery-15 change between no intervention and acupressure groups is 0.12 and for all comparisons is 0.27.

Secondary endpoint results are reported in Table 3 and Fig. 4. Mean patient satisfaction scores at POD 3 were statistically different among the three groups (P = 0.01). Overall, the acupressure had the highest satisfaction score, followed by the sham group and then the no-intervention group.

Table 3
Table 3:
Secondary endpoints
Fig. 4
Fig. 4:
Changes in secondary endpoints. Shows the mean (SD) values for vomiting, nausea and pain assessed on postoperative day 1 morning (baseline), postoperative day 1 afternoon, postoperative days 2 and 3. Morphine equivalent opioid consumption was calculated during recovery room (post anaesthesia care unit) stay (post anaesthesia care unit) from post anaesthesia care unit to randomisation, at postoperative days 1, 2 and 3. The blue line represents the no-intervention group, the red line the sham-intervention group and the green line the acupressure group.

A planned adherer-only analysis was conducted (total n=102), which included only patients who received either six treatments (acupressure and sham groups) or were hospitalised long enough to have received six treatments had they been in a treatment group (control group). No statistically significant differences were observed except in the results for patient satisfaction, which mirrored those from the modified intention-to-treat analysis.

Discussion

Previous studies have suggested that acupoint stimulation treatment could improve measures of postoperative QoR including pain,5,8,9 nausea,7 sleep10,11 and patient satisfaction.8 However, in our 3-group blinded, randomised controlled trial acupressure had minimal effect on QoR (as measured by QoR-15) and individual measures including pain scores, opioid (morphine equivalent) consumption, nausea and vomiting. According to Myles et al.21, the minimal clinically important difference in the QoR-15 indicative of an intervention significantly impacting on patient recovery is eight. We observed a mean difference of 6 (95% CI, −1.49 to 13.49) between the no-intervention and acupressure QoR-15 change scores. Although our observed mean difference is below the threshold of significance reported by Myles et al.,21 this threshold lies within the 95% CI and thus it cannot be ruled out with absolute certainty that there is no clinically relevant difference between the intervention and the control.

It is interesting that we also observed a trend towards better QoR-15 scores in the sham group compared with the no-intervention group but this trend was not observed between the acupressure and the sham groups. This may be due to a placebo effect from the three times per day visit to each patient that included touch, much too light to qualify for acupressure. Nevertheless, this very light touch could make patients feel ‘cared for’ and ‘attended to’ which may have resulted in the trend towards improved QoR-15 and patient satisfaction. Previous acupressure studies have used different types of ‘sham’ therapy, including significant pressure on nonacupoints or fake (i.e. low) pressure on real acupoints, as we employed in our study.22

Our study has several limitations. First, it is a single centre study so the results may not be generalisable to other hospitals. Second, it can be argued that acupressure therapy was inconsistently applied by nonacupuncturists. However, the previously published positive results from our training programme19 showed that study personnel could be trained to perform the acupressure consistently under supervision of one of our anaesthesiology faculty who is an experienced, licensed acupuncture therapist. We showed that individuals performing acupressure in our study were able to apply deep pressure as well as sham (i.e. extremely light) pressure consistently.19 Third, although our endpoint assessors were blinded to study group, patients were not, so their biases may have resulted in a placebo effect. Fourth, as discussed in our study protocol publication,18 this study's results can only be generalised to the same type of acupressure technique (acupoints used and frequency and duration of pressure). We chose multipoint acupressure because we wanted to combine acupoints that were reported to alleviate multiple postoperative symptoms including analgesia,9,23 PONV,24 ventilator-induced anxiety and dyspnoea.25 The frequency of the treatment administration was set at three times a day which is a reasonable frequency in peri-operative medicine, and has been used in previous studies.26,27

Our study has several strengths. These include a randomised controlled design including the addition of a third sham group. We included this sham group since we were concerned that, if acupressure was better than no intervention, it could be argued that the benefit was mediated by placebo (personal attention/touch) rather than through the acupressure itself. Another strength is the use of blinded individuals to assess patients, and separately trained un-blinded individuals who performed the acupressure and sham treatments. We also used an established instrument for primary endpoint assessment (QoR-15), and included relevant patient outcome measures such as pain, opioid (morphine equivalent) consumption, nausea and vomiting.

There are several reasons why we may have failed to show a benefit from acupressure therapy. Even though our estimated mean change scores for our sample size calculation were relatively accurate, there was more variation in our patients’ QoR-15 scores than anticipated. The observed effect size between the acupressure and control groups was small (Cohen's d = 0.30), so a larger sample size would have allowed more power to show this small benefit. However, even with a larger sample size, the results from the secondary outcomes (Fig. 4, Table 3) provide evidence of a lack of observable benefit to this type of therapy: most endpoints did not even trend towards a greater benefit.

The choice of the acupressure technique may have contributed to our inability to observe a significant difference; our study cannot rule out the effects of other acupoint stimulation techniques such as needle acupuncture, electroacupuncture12 or acupoint saline injection.28 Neurophysiological considerations could also contribute to our findings: acupoint stimulation effects are reported to be mediated by afferent nociceptive pathways.12 Patients treated in the postoperative period are exposed to intense systemic multimodal pain treatments acting on the nociceptive pathway that may have mitigated the beneficial effects of acupressure. In the context of peri-operative medicine, manual pressure may not be the optimal way to trigger acupoints compared with alternatives such as acupuncture or electro-acustimulation. In a review, Wang et al.17 reported beneficial effects on acute postoperative pain with manual acupuncture and electro-acustimulation.

In our blinded randomised trial acupressure therapy did not significantly improve QoR as assessed by the established QoR-15 tool. Patients may have ‘clinically’ benefited, but we cannot draw this conclusion with statistical certainty. A larger study is needed to detect this small effect size. Despite improved patient-reported satisfaction, no statistically significant benefits were observed with regard to individual measures such as pain score, opioid (morphine equivalent) consumption, nausea and vomiting.

Acknowledgements relating to this article

Assistance with the study: we would like to thank Jean Abbott, Sabeen Rizwan, Martha O’Brien and the entire Acute Pain Team of Stony Brook University Hospital for their assistance in conducting the study.

Financial support and sponsorship: EN was supported with a grant from the Insititut Hospitalo Universitaire de Strasbourg (Strasbourg, France), the Philippe foundation (NY, USA) and the Institut Servier (Paris, France). Otherwise departmental support from the Stony Brook Medicine Anesthesiology Department.

Conflicts of interest: none.

Presentation: presented in part at Stony Brook Department of Anesthesiology 2017 Academic Evening abstract session (Stony Brook, New-York).

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