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Chewing gum prophylaxis for postoperative nausea and vomiting in the intensive care unit: a pilot randomised controlled trial
Hussam Abdelkarim, Natasha Ciampoli, Lara Zwakman-Hessels, Jai N Darvall, Rinaldo Bellomo
Crit Care Resusc 2020; 22 (4): 321-326
- Hussam Abdelkarim 1
- Natasha Ciampoli 2
- Lara Zwakman-Hessels 3, 4
- Jai N Darvall 5, 6
- Rinaldo Bellomo 4, 5, 6
OBJECTIVE: To test the effectiveness of chewing gum in the prophylaxis of postoperative nausea and vomiting (PONV) in patients admitted to the intensive care unit (ICU) after surgery.
DESIGN: Prospective, open label, pilot randomised controlled trial.
SETTING: Two metropolitan ICUs.
PARTICIPANTS: Ninety postoperative adult patients admitted to the ICU.
INTERVENTION: Patients administered chewing gum, who chewed for at least 15 minutes every 4 hours, were compared with a control group, who were administered a 20 mL sip of water orally every 4 hours.
MAIN OUTCOME MEASURES: The primary outcome was the number of patient-reported episodes of nausea in the first 24 hours after the operation. Secondary outcomes included vomiting or dry retching episodes, and duration and severity of nausea.
RESULTS: Forty-six patients were randomly allocated to chewing gum and 44 patients to water. There was no difference between groups in the number of patients with nausea (10 [22%] chewing gum ν 12 [27%] control patients; P = 0.72), nausea episodes (22 episodes; [median, 0; IQR, 0–0] ν 21 episodes [median, 0; IQR, 0–1] per patient in each group respectively), vomiting/retching (2 [4%] chewing gum ν 6 [14%] control patients; P = 0.24), or duration/severity of nausea.
CONCLUSION: Regular postoperative administration of chewing gum in a surgical ICU patient cohort did not reduce nausea, vomiting or retching. The prevalence of PONV is less than previously reported. Our findings can inform future studies of PONV prophylaxis in post-surgical ICU patients.
TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry No. ACTRN12617001185358.
Funding/Source of Funding
The Austin Health ICU Research Fund supported this study. It did not have any role in the design, conduct or reporting of the study.
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PONV is also common in the intensive care unit (ICU), particularly after cardiac surgery. In a study of 400 cardiac surgical patients, the baseline incidence of nausea was reported at 47% and retching/vomiting at 37%. 5
Chewing gum stimulates gastrointestinal motility by vagal activation through effects of sham feeding and perhaps a reduction in systemic inflammation, 8, 9
In patients admitted to the ICU after surgery, we therefore performed a pilot randomised controlled trial of the prophylactic effectiveness of chewing gum on PONV compared with a control group administered 20 mL of oral water. We hypothesised that chewing gum would decrease the incidence, duration and severity of PONV in this patient group.
Study designThis was a prospective, open label, pilot randomised controlled trial conducted in two metropolitan ICUs. Ethics approvals from Austin Health (LNR/17/Austin/205) and Epworth Health (EH2017-288) were obtained. The trial was prospectively registered with the Australian New Zealand Clinical Trial Registry (No. ACTRN12617001185358).
This trial was conducted in compliance with the Consolidated Standards of Reporting Trials (CONSORT) statement.
Eligible patients were those aged 18 years or more; admitted to the ICU within 16 hours after non-oropharyngeal, maxillary or oesophageal surgery; and anticipated to stay in the ICU for more than 12 hours. Patients who remained mechanically ventilated, who were deemed too sedated (based on the judgement of attending clinical staff), or who had partial or full dentures were excluded.
Patients were enrolled after written informed consent was obtained, either before or after the surgery. Patients were randomly allocated to either the intervention chewing gum group (Falim [Kent Gida], lightly mint flavoured, sugarless gum; ingredients: gum base, flavouring, colouring [E171], antioxidants [E321, E320]), which was chewed for at least 15 minutes every 4 hours, or to a control group, who were administered a 20 mL sip of water orally every 4 hours. Randomisation was achieved using a computerised random number generator; allocation concealment was done via sequentially numbered envelopes. Participants were enrolled by the two investigators (HA and NC). All patients were allowed other oral intake as tolerated and permitted by the surgical team. We pre-determined a cardiac surgery subgroup.
All enrolled patients had access to a standardised antiemetic rescue protocol:
- first line — ondansetron 8 mg intravenous;
- second line — droperidol 0.625 mg intravenous;
- third line — metoclopramide 10 mg intravenous;
- fourth line — prochlorperazine 12.5 mg intravenous.
The primary outcome was the number of patient-reported nausea episodes in the first 24 hours after the operation, with secondary outcomes including the combination of vomiting or dry retching episodes, duration of nausea episodes, use of rescue antiemetics in the two groups, and the severity of nausea as reported in a visual analogue scale from 0 to 10 every 4 hours.
Sample size calculationWe based our power calculation on a pilot study comparing chewing gum with ondansetron, with a full resolution rate of PONV in the chewing gum group of 75% and in the ondansetron group of 39%. 16
Statistical analysisData are expressed as means with standard deviation (SD), when normally distributed, or median and interquartile range (IQR), when non-parametric. The χ2 or Fisher exact test was applied to categorical variables (including the primary outcome), with normally distributed continuous variables compared using the Student t test, and the Mann– Whitney U test used for non-parametric continuous variables. A P < 0.05 indicated statistical significance. All statistical analyses were performed using R, version 3.4.2 (R Foundation for Statistical Computing, Vienna, Austria).
ResultsBetween October 2017 and January 2019, we screened a total of 171 patients, after exclusions (28 patients with dentures, 25 patients remaining mechanically ventilated, 19 refusals, and five patients too drowsy), 90 patients were enrolled. Forty-six patients were randomised to the chewing gum group and 44 patients to the control group (Figure 1).
The demographic features of enrolled patients are outlined in Table 1. Groups were similar in baseline characteristics, including Apfel PONV risk scores. Thirty-seven patients (41%) were admitted after cardiac surgery, 14 (15%) after bariatric surgery, and 16 (17%) after other gastrointestinal surgery, with the remainder undergoing other procedures.
Gum was chewed on 148 occasions by all patients randomised to the chewing gum group (median, 3 occasions; IQR, 2–4). It was not administered on 93 occasions (38%): 72 occasions because the patient was sleeping, 15 occasions because the patient refused, and six occasions due to patient drowsiness. No gum was swallowed or aspirated.
There was no difference between groups in the number of patients with nausea (10 [22%] chewing gum patients [95% CI, 4–15; 9–34%] ν 12 [27%] control patients [95% CI, 5–18; 14–41%]; P = 0.72) or vomiting (2 [4%] chewing gum ν 6 [14%] control patients; P = 0.24) with a combined incidence of these outcomes of 12 (16%) versus 18 (41%) (Table 2). There was no difference in the number of patient-reported nausea episodes (total 22 nausea episodes per patient in the chewing gum group [median, 0; IQR, 0–0] ν 21 in the control group [median, 0; IQR, 0–1]; P = 0.706). There was also no difference in the degree, duration or severity of nausea; number of episodes of vomiting or retching; or the use of rescue antiemetics (Table 2). Thirty-seven patients were enrolled in the pre-determined cardiac surgical subgroup: 19 in the chewing gum group and 18 in the water group, with no differences in outcomes between groups.