Effects of Preoperative Gum Chewing on Sore Throat After General Anesthesia With a Supraglottic Airway Device: A Randomized Controlled Trial : Anesthesia & Analgesia

Secondary Logo

Journal Logo

Featured Articles: Original Clinical Research Report

Effects of Preoperative Gum Chewing on Sore Throat After General Anesthesia With a Supraglottic Airway Device: A Randomized Controlled Trial

Wang, Tingting MD; Wang, Qi RN; Zhou, Haiyang RN; Huang, Shaoqiang PhD, MD

Author Information
Anesthesia & Analgesia 131(6):p 1864-1871, December 2020. | DOI: 10.1213/ANE.0000000000004664


See Article, p 1862


  • Question: Is there a simple and effective way to reduce the incidence of postoperative sore throat (POST) after a short surgery with a supraglottic airway device?
  • Findings: Chewing gum before surgery can effectively reduce POST with a streamlined liner of the pharyngeal airway (SLIPA) for hysteroscopic surgery, especially in patients with pharyngeal mucosal injury.
  • Meaning: With a significant reduction in POST, chewing gum preoperatively is beneficial for patients undergoing short hysteroscopic surgery with a supraglottic airway device.

Postoperative sore throat (POST) is a common complaint after surgery, and it has been rated by patients as the eighth worst adverse effect in the postoperative period.1 Indeed, POST affects patient satisfaction and can affect activity after discharge. The supraglottic airway (SGA) device is widely used in general anesthesia because it causes fewer injuries and is more convenient to use than endotracheal intubation. However, regardless of the type of SGA device used, POST is still a common complication, with a reported incidence as high as 50%.2

The causes of POST may be as follows. First, the patient’s throat may be damaged during insertion of the SGA device.3 Second, due to the influence of surgical stress and the anesthetic, the immune function of the patient is suppressed to some extent during surgery, and the bacteria in the oral pharynx reproduce abnormally, which causes damage to the oral pharyngeal mucosa and may even generate ulcers, in turn causing a sore throat.4

There are currently some pharmacological and nonpharmacological measures to alleviate POST. Nonpharmacological methods for preventing intubation-related sore throat include using smaller-sized tubes, lubricating the tube with water-soluble jelly, careful airway instrumentation, intubation after full relaxation, gentle oropharyngeal suctioning, and extubation under deep anesthesia and with a fully deflated tracheal tube cuff.5 Pharmacological measures for attenuating POST include inhalation of beclomethasone6 or fluticasone propionate7; gargling with azulene sulfonate,8 aspirin,9 or ketamine10; gargling9 or spraying11 benzydamine hydrochloride; intravenous (IV) dexamethasone12; oral clonidine13; topical or systemic lidocaine14; and ingestion of strepsils tablets.15 Each of these approaches has limitations and variable success rates; thus, no approach has become established in routine clinical use.

In the past decade, studies have shown that xylitol in chewing gum may inhibit the growth, metabolism, and polysaccharide production of Streptococcus mutans, which accounts for the highest proportion of the natural flora in the oral cavity.16–18 Subsequent biofilm formation reduction may lead to some reduction in the number of bacteria.18 Furthermore, chewing gum can promote salivary gland secretion, resulting in lubrication and cleansing of the oral cavity.18 Considering the benefits of chewing gum for the patient’s oral cavity and mucous membranes, we speculated that preoperative gum chewing may reduce the incidence of POST after SGA device use.

We conducted a randomized controlled trial to investigate the effect of preoperative gum chewing on POST in patients undergoing hysteroscopic surgery with a streamlined liner of pharyngeal airway (SLIPA). Our primary aim was to determine the incidence of POST scores >3 within 24 hours after surgery, and the secondary outcomes included the POST scores 2, 6, and 24 hours after surgery.


This was a prospective, randomized, controlled, observer-blinded clinical study. This study was approved by the Ethics Committee of the Obstetrics and Gynaecology Hospital affiliated with Fudan University (institutional review board 2019-37), and written informed consent was obtained from all subjects participating in the trial. Before patient enrollment, the trial was registered at clinicaltrials.gov (NCT03885752, principal investigator: Tingting Wang, date of registration: March 21, 2019).

The study was conducted between March 25 and May 25, 2019. One hundred forty American Society of Anesthesiologists (ASA) physical status I or II patients who were 20–65 years of age with body mass index (BMI) <30 and who were undergoing elective hysteroscopic surgery with the SLIPA were randomly allocated to 2 groups of 70 patients each. The exclusion criteria were as follows: patients with chronic laryngitis, chronic bronchitis, asthma, gastroesophageal reflux, allergies to study drugs, recent use of nonsteroidal anti-inflammatory drugs (NSAIDs), a history of upper respiratory tract infection, smoking and steroid therapy in the past week, failure to communicate normally, and Mallampati grade >2.

Patients included in the study were divided into the gum group (group G) and the control group (group C) by a computer-generated random number table before surgery. After enrollment, patients were excluded from the study if the following conditions were encountered: the SGA device implantation was not successful or performed 2 or more times, the SGA device was changed to endotracheal intubation, or the operation time was longer than 1 hour.

During a preanesthetic visit at the inpatient unit 4 hours before surgery, patients were familiarized with the questionnaire to be used for POST. Coded, sealed, opaque envelopes were used to ensure that the allocations were concealed until consent was obtained. Patients had to follow the current recommendations regarding preoperative fasting before elective surgery (6 hours fasting for solids and 2 hours fasting for clear fluids).

In the preoperative waiting area before transfer to the operating room, patients in group G chewed 1 piece of herbal sugar-free gum (Mars-Wrigley Confectionery, Chicago, IL) for 2 minutes and then spat it out. According to the product description, 1 piece of gum weighs approximately 1.4 g, contains 5% xylitol, maltitol, sorbitol, glycerin, D-mannitol, edible flavor, and 3 herbal ingredients: 0.01% Lonicera japonica, 0.01% Siraitia grosvenorii powder, and 0.01% chrysanthemum powder. Group C was asked to swallow twice without any additional treatment. Electrocardiogram (ECG), blood pressure (BP), blood oxygen saturation (Spo2), and heart rate (HR) were routinely monitored after patients entered the operating room. According to the principle that the maximum width of the SLIPA (Hangzhou Fushan Medical Equipment Co, Ltd, Hangzhou, China) is equal to the distance between patient’s 2 thyroid cartilage angles, the appropriate model was selected and then lubricated with paraffin oil (Figure 1).2,19

Figure 1.:
A, The frontal views of the SLIPA. 1: The toe is positioned at the esophageal entrance. 2: The bridge seals the base of the tongue. 3: The heel sets in the nasopharynx. 4: The proximal shaft is a stiffer breathing tube that leads from the body to the connector. B, SLIPA in position. SLIPA indicates streamlined liner of pharyngeal airway.

General anesthesia was induced with 0.2 μg·kg−1 sufentanil and 2 mg·kg−1 propofol. To assist with the SGA insertion technique, 1 mg·kg−1 succinylcholine was administered after loss of consciousness; this has been proven to increase the successful insertion rate, increase the sealing pressure, decrease leakage volumes, and decrease the personal force.20 One minute later, a single operator blinded to the group allocation of the patient inserted the SLIPA device. If the initial attempt at the insertion of the SLIPA was unsuccessful, the head was repositioned to permit 1 further attempt. If the second attempt was unsuccessful, it was recorded as a failure, and the patient received a supplementary dose of propofol up to 1 mg·kg−1 IV. Then, either an LMA® ProSeal™ (PLMA; The Laryngeal Mask Company Ltd, Maidenhead, United Kingdom) or endotracheal intubation was selected. Pressure-controlled ventilation was initiated with a mixture of 50% oxygen and 50% air, a respiratory rate of 12 cycles·minute−1, zero end-expiratory pressure, inspiratory-to-expiratory ratio (I:E) of 1:2 and an adjusted end-tidal CO2 maintained at approximately 35–40 mm Hg. Propofol was maintained by intraoperative continuous infusion. Ondansetron (4 mg) and flurbiprofen (50 mg) were injected IV to prevent postoperative nausea, vomiting, and pain. The SLIPA was removed after the patient was awake and spontaneous breathing was recovered.

It was immediately recorded whether there were blood stains on the surface of the SLIPA. Another investigator blinded to the group allocation of the patients evaluated POST 2, 6, and 24 hours after surgery. POST was evaluated by the numerical rating scale (NRS), which ranges from 0 to 10 points, with 0 indicating no pain, 1–3 indicating mild discomfort, 4–6 indicating moderate pain, and 7–10 indicating severe pain.

In this study, the primary outcomes were the incidence of moderate/severe POST within 24 hours after surgery. The definition of moderate/severe POST is one or more events with POST score (NRS) >3 at any time point of 2, 6, and 24 hours after surgery. The secondary outcomes included the POST (NRS) scores 2, 6, and 24 hours after surgery. To further study POST in patients with laryngeal injury, we conducted a subgroup analysis with patients subdivided based on whether the SLIPA had blood stains on it, which recorded the NRS scores of patients with and without blood on the SGA device and the incidence of patients with moderate/severe POST. If the patient accidentally swallowed the gum while chewing the gum, the patient was excluded from the study, and the patient was given general anesthesia with an endotracheal tube instead of an SGA device.

In a preliminary trial involving 20 patients undergoing hysteroscopic surgery with SLIPA, the incidence of POST (NRS) scores >3 within 24 hours after surgery was 40%. According to the sample size formula (2-sample problem with binary responses) of correlated observations,21 we assumed that the incidence of moderate/severe POST in the experimental group was 20% and the incidence in the control group was 40%, the experimental group and the control group each accounted for 50% (π1 = π0 = 1/2), and the correlation of the response within-subject across the repeated measurements was 0.2; therefore, the measurement was repeated 3 times (2, 6, and 24 hours), a 2-sided test with a type I error (α value) of .05 and a type II error (β level) of .2 was considered, and at least 98 patients were needed in total. Considering the possibility of a 20% drop-out rate, a total sample size of 118 patients was needed.

The G and C groups were compared for balance in terms of demographics and surgical variables by calculating standardized differences. Imbalance was defined as a standardized difference with absolute value >1.96 × (2/69)1/2 = 0.334.22

Categorical variables were defined as the numbers and percentages and evaluated with the Pearson χ2 test. Continuous numeric variables were assessed for the normality of their distribution (Kolmogorov-Smirnov test). Normally distributed measurement data are presented as the mean ± standard deviation (SDs). Between-group comparisons were made using Student t tests. Non-normally distributed data are presented as the median (interquartile range [IQR]; [range]) and statistically analyzed using Mann-Whitney U tests.

During the evaluation period of 24 hours after surgery, the incidence of moderate/severe POST was compared between the groups using the generalized estimating equation (GEE). We used binomial probability distribution, logit link function, independent structure within the subjects since the model had the lowest quasi-likelihood under the independence model criterion (QIC) value of 243.186, the time interval for POST as the within-subject effect, the presence or absence of POST as the categorical dependent variable and the study drug (gum versus non-gum) as the independent factor in GEE analysis. Further, GEE was conducted to determine the effect of gum chewing on the incidence of moderate/severe POST when adjusted for risk factors, that is, the duration of surgery (0: less than 30 minutes; and 1: 30 minutes or more) and blood stains on the SLIPA (0: no; and 1: yes) and then reported as an odds ratio (OR) with 95% confidence interval (CI). We performed statistical analyses with SPSS version 25.0 (SPSS, Inc, Chicago, IL). A value of P < .05 was considered statistically significant.


Of the 140 patients included in the study, 1 patient in each group was excluded due to more than 1 insertion attempt with the SLIPA, and 69 patients in each group were ultimately evaluated (Figure 2). None of the patients swallowed the gum. The types of surgery were endometrial polypectomy, hydrotubation, intrauterine adhesion decomposition, and hysteromyoma removal. Patient demographic data and surgical characteristics were comparable between the 2 groups (Table 1).

Table 1. - Demographic and Surgical Profiles of the Patients
Variable Group G
(n = 69)
Group C
(n = 69)
Absolute Standardized Difference
Age (y) 44.2 ± 13.6 42.2 ± 11.3 0.160
Weight (kg) 56.3 ± 8.2 55.8 ± 7.5 0.064
BMI (kg/m2) 21.8 ± 1.4 21.4 ± 1.2 0.307
 Endometrial polypectomy 25 (36%) 23 (33%) 0.063
 Hydrotubation 14 (20%) 12 (17%) 0.077
 Intrauterine adhesion decomposition 16 (23%) 17 (25%) 0.047
 Hysteromyoma removal 14 (20%) 17 (25%) 0.120
Values are in mean ± standard deviation, number, number (%). Imbalance was defined as the absolute standard difference exceeding 1.96*sqrt [(n1 + n2)/n1n2] = 0.334, where n1 = n2 = 69.
Abbreviations: BMI, body mass index; C group, the control group; G group, the gum group.

Figure 2.:
CONSORT recruitment diagram. CONSORT indicates Consolidated Standards of Reporting Trials; Group C, control group; Group G, gum group; n, number of pairs; SLIPA, streamlined liner of pharyngeal airway.

There were 2, 6, and 2 patients in group G at 2, 6, and 24 hours after surgery occurred with moderate/severe POST, respectively. Among them, 1 patient had NRS >3 at 3 time points, and 1 patient had NRS >3 at both 6 and 24 hours. Therefore, a total of 7 patients in group G developed moderate/severe POST. Moderate/severe POST occurred in 8, 19, and 9 patients in group C at 2, 6, and 24 hours after surgery, respectively. Among them, 4 patients had NRS >3 at 2 and 6 hours after surgery, and 4 patients had NRS >3 at 6 and 24 hours. Therefore, a total of 28 patients in group C developed moderate/severe POST. In consequence, the incidence of moderate/severe POST within 24 hours after surgery was significantly lower in group G (10.1%, 7/69) than in group C (40.6%, 28/69) (P = .044) (Supplemental Digital Content, Figure 1, https://links.lww.com/AA/D12). The median (interquartile range [range]) scores at 2, 6, and 24 hours after surgery in group G were lower than those in the control group at the same times (2 hours: 0 [0–3 {0–4}] vs 3 [0–3 {0–6}], P = .048; 6 hours: 0 [0–3 {0–6}] vs 2 [0–4 {0–6}], P = .048; 24 hours: 0 [0–1 {0–7}] vs 0 [0–2 {0–6}], P = .011) (Table 2).

Table 2. - Perioperative Profiles of the Patients
G Group
(n =69)
C Group
(n =69)
Time from intervention to anesthesia (min) 9.5 ± 1.2 9.8 ± 1.4 .231a
Operation duration (min) 13.5 ± 11.3 12.8 ± 10.9 .730a
Blood stain on SLIPA 14 (20.3%) 26 (37.7%) .024b
 POST (NRS > 3)c 2 (14.3%) 19 (73.1%) <.001b
 Non-POST (NRS ≤ 3) 12 (85.7%) 7 (26.9%)
Nonblood stain on SLIPA 55 (79.7%) 43 (62.3%) .024b
 POST (NRS > 3)c 5 (9.1%) 9 (20.9%) .145b
 Non-POST (NRS ≤ 3) 50 (90.9%) 34 (79.1%)
NRS scored
 2 h after surgery 0 (0–3 [0–4]) 3 (0–3 [0–6]) .048
 6 h after surgery 0 (0–3 [0–6]) 2 (0–4 [0–6]) .048
 24 h after surgery 0 (0–1 [0–7]) 0 (0–2 [0–6]) .011
Values are in mean ± standard deviation, number, number (%), median (interquartile range [range]).
Abbreviations: C group, the control group; G group, the gum group; NRS, numerical rating scale; POST, postoperative sore throat; SLIPA, the streamlined liner of the pharynx airway.
aStudent t tests.
bPearson χ2 test.
cPostoperative NRS score for sore throat was >3 at any time within 2, 6, and 24 h after surgery, and it was considered as moderate/severe POST within 24 h.
dNRS score was non-normally distributed, so Mann-Whitney U tests were performed.

There were 14 patients (20.3%, 14/69) in group G who had blood stains on the SLIPA, which was significantly lower than the number in group C (37.7%, 26/69) (P = .024) (Table 2). Considering that a bloody SGA device reflects mucosal injury in the throat to some extent, we conducted a subgroup analysis according to whether the SLIPA had blood stains. In patients with blood stains, the incidence of POST scores >3 was significantly lower in group G (14.3%, 2/14) than in group C (73.1%, 19/26) (P < .001) (Table 2). However, in patients without blood stains, there was no statistically significant difference between group G and C (5/55, 9.1% vs 9/43, 20.9%; P = .145). Because of the small sample size, the same trend was found in group G, but the difference was not statistically significant. An overall comparison was conducted, and the results showed that the NRS scores of the blood stains group at 2, 6, and 24 hours after surgery were significantly higher than those of the nonblood stains group (2 hours: P < .001; 6 hours: P < .001; 24 hours: P = .01) (Table 3). In the control group, patients with blood stains had significantly higher NRS scores at 2 and 6 hours than patients without blood stains (2 hours: 3 [3–3 {0–6}] vs 0 [0–3 {0–5}], P = .001; 6 hours: 4 [0–5 {0–6}] vs 1 [0–3 {0–6}], P = .002).

Table 3. - NRS Scores of Blood Stains and Nonblood Stains on SLIPA Were Compared Between the 2 Groups
G Group C Group Total
NRS Comparison (After Surgery) Blood (n = 14) Nonblood (n = 55) P
Blood (n = 26) Non
blood (n = 43)
Blood (
n = 40)
blood (
n = 98)
2 h 3 (0–3 [0–3]) 0 (0–3 [0–4]) .132 3 (3–3 [0–6]) 0 (0–3 [0–5]) .001 3 (2–3 [0–6]) 0 (0–3 [0–5]) <
6 h 2 (0–3 [0–4]) 0 (0–3 [0–6]) .130 4 (0–5 [0–6]) 1 (0–3 [0–6]) .002 3 (0–4 [0–6]) 0 (0–3 [0–6]) <
24 h 1 (0–2 [0–3]) 0 (0–1 [0–7]) .083 2 (0–3 [0–6]) 0 (0–2 [0–4]) .118 1 (0–3 [0–6]) 0 (0–1 [0–7]) .010
Values are median (interquartile range [range]).
Abbreviations: C group, the control group; G group, the gum group; NRS, numerical rating scale; SLIPA, the streamlined liner of the pharynx airway.
aUsing Mann-Whitney U tests.

Table 4. - Generalized Estimating Equation Was Conducted to Determine the Effect of Various Interventions on the Incidence of Moderate/Severe POST
Univariable Analysis Multivariable Analysis
Moderate/Severe Sore Throat Incidence Odds Ratio (95% CI) P Odds Ratio (95% CI) P
Group G/C 0.325 (0.127–0.828) .018 0.386 (0.153–0.976) .044
Duration of operation 0.176 (0.022–1.274) .085 0.168 (0.022–1.280) .085
Blood stain on SLIPA 2.723 (1.283–5.779) .009 2.374 (1.157–4.870) .018
Using the generalized estimating equation with binomial probability distribution, logit link function for this analysis.
Abbreviations: C group, the control group; CI, confidence interval; G group, the gum group; POST, postoperative sore throat; SLIPA, streamlined liner of the pharyngeal airway.

A GEE was used to determine the effects of various interventions on the incidence of moderate/severe POST (Table 4). The results showed that after controlling for the risk factors of operation time and whether there were blood stains on the SLIPA, the odds of moderate/severe sore throat after chewing gum before surgery was reduced to 0.386 (95% CI, 0.153–0.976; P = .044) compared with that observed without chewing gum. A SLIPA with blood stains was associated with a 2.374-fold increased odds of moderate/severe POST (95% CI, 1.157–4.870). For short operations of <1 hour, the duration of surgery (<30 minutes or >30 minutes) had no effect on the odds of moderate/severe POST (OR 0.168, 95% CI, 0.022–1.280).


To our knowledge, we have reported the preventive effect of chewing gum on POST for the first time. The results showed that preoperatively chewing gum can significantly reduce the incidence of POST scores >3 within 24 hours after surgery, with values approximately 75% lower in group G (10.1%) than in the control group (40.6%). The NRS score within 24 hours after surgery and the rate of blood stain on SLIPA were significantly reduced in group G compared with the control group. Subgroup analysis found that the incidence of moderate/severe POST in SLIPA patients with blood stains in group G was significantly lower than that in group C.

Gum is a popular food. Chewing gum has many benefits for human health. A recent study found that chewing gum is a simple intervention for reducing postoperative ileus after colorectal surgery.23 Chewing gum can also treat nausea and vomiting after general anesthesia for laparoscopic or breast surgery in female patients.24 The current study reports an interesting and exciting finding. Our primary result is that, after controlling for possible influencing factors, the risk of moderate/severe POST after chewing gum was reduced to 0.386 (95% CI, 0.153–0.976; P = .044) compared to that without chewing gum. This easy intervention may be able to reduce the incidence and degree of POST, a common occurrence following general anesthesia, and although clinicians often regard it as a relatively minor complication, patients perceive avoidance as being of great importance.

Another interesting result of this study is that the percentage of SGA devices with blood stains was significantly reduced in the gum group. There are several possible explanations for why chewing gum reduces traumatic airway insertion. The nerve-mediated salivary reflex is modulated by nerve signals from other centers in the central nervous system, which is most obvious as hyposalivation at times of anxiety.25 Before surgery, patients have a certain level of anxiety and tension, which may lead to decreased saliva secretion. Moreover, salivary flow increases above unstimulated levels because of the gustatory stimulation from the sweetening and flavoring agents and because of the mechanical stimulation from chewing.26 Saliva can lubricate the mouth and mucous membranes,18 which may reduce the traumatic airway when the SGA is inserted.

Another surprising result worth mentioning is that in patients with a blood-stained SLIPA, the incidence of moderate/severe POST in group G was nearly one-fifth of that in the control group (14.3% vs 73.1%; P < .001). This result seems to suggest that chewing gum before surgery is more effective in reducing POST in patients with pharyngeal mucosal injury. This may be due to the direct or indirect antibacterial effects of chewing gum.

Amylase, the single most abundant protein in saliva, reduces the availability of substrates for microbial growth.27 In addition, certain protein families in saliva have bacteriostatic action. For example, the histatins appear to be particularly effective at controlling fungal growth in the mouth. Statherin has been shown to be an important boundary lubricant.27 The ionic components of saliva, particularly calcium, have the beneficial effect of preventing the excessive precipitation of calcium onto bacteria-covered sites.28

In addition to the effect of saliva, gum contains active ingredients that may also play a role in reducing POST. Xylitol is a birch sugar that causes local “bacterial interference” by inhibiting bacterial growth and adherence to the pharyngeal wall, which should reduce the inflammation and the severity of symptoms caused by bacterial infections.29 Mint has been shown to treat the minor sore throat and minor mouth or throat irritation.30 Furthermore, as important traditional Chinese medicines, Lonicera japonica, Siraitia grosvenorii, and Chrysanthemum have anti-inflammatory, immunomodulatory, antimicrobial, and antibacterial activities.31–33

Another possible explanation for this is that saliva activates the plasma coagulation system and may limit bacterial spread. Recent research suggests that saliva activates the coagulation system, including factor XII (FXII) of the intrinsic pathway, and that saliva-induced clotting entraps streptococci (which account for the highest proportion of the natural flora in the oral cavity).34 Saliva-induced coagulation mechanisms have been previously reported, with tissue factor (TF) in saliva, which externally triggers clotting.35 The clots may protect the damaged epithelium, and/or inhibit the diffusion of bacterial products such as exotoxins.34

There was early controversy as to whether chewing gum before surgery violated fasting guidelines. Recently, more evidence has supported the suggestion that preoperative chewing gum has no significant clinical difference in residual gastric volume or gastric juice acidity. Even whether gum contains sugar has no impact on gastric juice volume or gastric pH.36 In 2011, the European Society of Anaesthesiology stated that “patients should not have their operation canceled or delayed just because they are chewing gum.”37 A recent randomized, cross-sectional trial of healthy volunteers also showed that chewing gum for a long time (45 minutes) did not affect gastric emptying after drinking water and had no effect on gastric volume.38 Therefore, preoperative gum chewing is feasible for patients.

This study has several limitations. First, we selected patients undergoing hysteroscopic surgery. The average duration of the operation and intervention with anesthesia were both approximately 10 minutes. Whether chewing gum can reduce POST with a prolonged operation and intervention with anesthesia still needs further research. Second, the optimal duration of chewing is unclear. A previous study found that the peak salivary flow rate occurs in the first 1 or 2 minutes of gum chewing and then decreases with time.39 In contrast, some scholars think the flow of saliva may be linearly related to the weight of the gum.40 In the future, the effect of the length of time spent chewing preoperatively on the incidence of POST should be studied. Third, the mechanism of reducing POST was not directly confirmed in our study. However, according to the previous literature, these proposed explanations are reasonable. Fourth, we studied sugar-free gum from the Mars-Wrigley Confectionery, which contains xylitol, mint, and herbal ingredients. Whether other types of gum have the same effect remains to be seen.

In summary, preoperative gum chewing can effectively prevent the occurrence of POST after hysteroscopic surgery with the SLIPA, which is conducive to the postoperative recovery of patients. That such a simple, inexpensive, and low-risk prophylactic intervention effectively prevents a common and annoying complication of SGA device insertion is remarkable and seems well worth implementing in routine clinical practice.


The authors thank Jiang-Nan Wu, MD, Department of Clinical Epidemiology, Obstetrics & Gynecology Hospital, Fudan University, for statistical advice.


Name: Tingting Wang, MD.

Contribution: This author helped collect and analyze the data and write the article.

Name: Qi Wang, RN.

Contribution: This author helped design the study and conduct the study.

Name: Haiyang Zhou, RN.

Contribution: This author helped collect and analyze the data.

Name: Shaoqiang Huang, PhD, MD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the article.

This manuscript was handled by: David Hillman, MD.


1. Segaran S, Bacthavasalame AT, Venkatesh RR, Zachariah M, George SK, Kandasamy R. Comparison of nebulized ketamine with nebulized magnesium sulfate on the incidence of postoperative sore throat. Anesth Essays Res. 2018;12:885–890.
2. Miller DM, Camporota L. Advantages of ProSeal and SLIPA airways over tracheal tubes for gynecological laparoscopies. Can J Anaesth. 2006;53:188–193.
3. Reier CE. Bleeding, dysphagia, dysphonia, dysarthria, severe sore throat, and possible recurrent laryngeal, hypoglossal, and lingual nerve injury associated with routine laryngeal mask airway management: where is the vigilance? Anesthesiology. 2004;101:1241–1242.
4. Chen CY, Kuo CJ, Lee YW, Lam F, Tam KW. Benzydamine hydrochloride on postoperative sore throat: a meta-analysis of randomized controlled trials. Can J Anaesth. 2014;61:220–228.
5. Al-Qahtani AS, Messahel FM. Quality improvement in anesthetic practice incidence of sore throat after using small tracheal tube. Middle East J Anesthesiol. 2005;18:179–183.
6. el Hakim M. Beclomethasone prevents postoperative sore throat. Acta Anaesthesiol Scand. 1993;37:250–252.
7. Tazeh-Kand NF, Eslami B, Mohammadian K. Inhaled fluticasone propionate reduces postoperative sore throat, cough, and hoarseness. Anesth Analg. 2010;111:895–898.
8. Ogata J, Minami K, Horishita T, et al. Gargling with sodium azulene sulfonate reduces the postoperative sore throat after intubation of the trachea. Anesth Analg. 2005;101:290–293.
9. Agarwal A, Nath SS, Goswami D, Gupta D, Dhiraaj S, Singh PK. An evaluation of the efficacy of aspirin and benzydamine hydrochloride gargle for attenuating postoperative sore throat: a prospective, randomized, single-blind study. Anesth Analg. 2006;103:1001–1003.
10. Chan L, Lee ML, Lo YL. Postoperative sore throat and ketamine gargle. Br J Anaesth. 2010;105:97.
11. Huang YS, Hung NK, Lee MS, et al. The effectiveness of benzydamine hydrochloride spraying on the endotracheal tube cuff or oral mucosa for postoperative sore throat. Anesth Analg. 2010;111:887–891.
12. Park SH, Han SH, Do SH, Kim JW, Rhee KY, Kim JH. Prophylactic dexamethasone decreases the incidence of sore throat and hoarseness after tracheal extubation with a double-lumen endobronchial tube. Anesth Analg. 2008;107:1814–1818.
13. Maruyama K, Yamada T, Hara K. Effect of clonidine premedication on postoperative sore throat and hoarseness after total intravenous anesthesia. J Anesth. 2006;20:327–330.
14. Tanaka Y, Nakayama T, Nishimori M, Sato Y, Furuya H. Lidocaine for preventing postoperative sore throat. Cochrane Database Syst Rev. 2009;3:CD004081.
15. Ebneshahidi A, Mohseni M. Strepsils® tablets reduce sore throat and hoarseness after tracheal intubation. Anesth Analg. 2010;111:892–894.
16. Söderling EM, Ekman TC, Taipale TJ. Growth inhibition of Streptococcus mutans with low xylitol concentrations. Curr Microbiol. 2008;56:382–385.
17. Söderling EM. Xylitol, mutans streptococci, and dental plaque. Adv Dent Res. 2009;21:74–78.
18. Hashiba T, Takeuchi K, Shimazaki Y, Takeshita T, Yamashita Y. Chewing xylitol gum improves self-rated and objective indicators of oral health status under conditions interrupting regular oral hygiene. Tohoku J Exp Med. 2015;235:39–46.
19. Hooshangi H, Wong DT. Brief review: the Cobra Perilaryngeal Airway (CobraPLA and the Streamlined Liner of Pharyngeal Airway (SLIPA) supraglottic airways. Can J Anaesth. 2008;55:177–185.
20. Liao AH, Lin YC, Bai CH, Chen CY. Optimal dose of succinylcholine for laryngeal mask airway insertion: systematic review, meta-analysis and metaregression of randomised control trials. BMJ Open. 2017;7:e014274.
21. Liu G, Liang KY. Sample size calculations for studies with correlated observations. Biometrics. 1997;53:937–947.
22. Austin PC. Balance diagnostics for comparing the distribution of baseline covariates between treatment groups in propensity-score matched samples. Stat Med. 2009;28:3083–3107.
23. Topcu SY, Oztekin SD. Effect of gum chewing on reducing postoperative ileus and recovery after colorectal surgery: a randomised controlled trial. Complement Ther Clin Pract. 2016;23:21–25.
24. Darvall JN, Handscombe M, Leslie K. Chewing gum for the treatment of postoperative nausea and vomiting: a pilot randomized controlled trial. Br J Anaesth. 2017;118:83–89.
25. Carpenter GH. The secretion, components, and properties of saliva. Annu Rev Food Sci Technol. 2013;4:267–276.
26. Inui T, Palmer RJ Jr, Shah N, Li W, Cisar JO, Wu CD. Effect of mechanically stimulated saliva on initial human dental biofilm formation. Sci Rep. 2019;9:11805.
27. Harvey NM, Carpenter GH, Proctor GB, Klein J. Normal and frictional interactions of purified human statherin adsorbed on molecularly-smooth solid substrata. Biofouling. 2011;27:823–835.
28. Hay DI, Schluckebier SK, Moreno EC. Saturation of human salivary secretions with respect to calcite and inhibition of calcium carbonate precipitation by salivary constituents. Calcif Tissue Int. 1986;39:151–160.
29. Tapiainen T, Luotonen L, Kontiokari T, Renko M, Uhari M. Xylitol administered only during respiratory infections failed to prevent acute otitis media. Pediatrics. 2002;109:E19.
30. Al-Bayati FA. Isolation and identification of antimicrobial compound from Mentha longifolia L. leaves grown wild in Iraq. Ann Clin Microbiol Antimicrob. 2009;8:20.
31. Shang X, Pan H, Li M, Miao X, Ding H. Lonicera japonica Thunb.: ethnopharmacology, phytochemistry and pharmacology of an important traditional Chinese medicine. J Ethnopharmacol. 2011;138:1–21.
32. Li C, Lin LM, Sui F, et al. Chemistry and pharmacology of Siraitia grosvenorii: a review. Chin J Nat Med. 2014;12:89–102.
33. Hosseini S, Imenshahidi M, Hosseinzadeh H, Karimi G. Effects of plant extracts and bioactive compounds on attenuation of bleomycin-induced pulmonary fibrosis. Biomed Pharmacother. 2018;107:1454–1465.
34. Wollein Waldetoft K, Mohanty T, Karlsson C, et al. Saliva-induced clotting captures streptococci: novel roles for coagulation and fibrinolysis in host defense and immune evasion. Infect Immun. 2016;84:2813–2823.
35. Berckmans RJ, Sturk A, van Tienen LM, Schaap MC, Nieuwland R. Cell-derived vesicles exposing coagulant tissue factor in saliva. Blood. 2011;117:3172–3180.
36. Ouanes JP, Bicket MC, Togioka B, Tomas VG, Wu CL, Murphy JD. The role of perioperative chewing gum on gastric fluid volume and gastric pH: a meta-analysis. J Clin Anesth. 2015;27:146–152.
37. Smith I, Kranke P, Murat I. European Society of Anaesthesiology. Perioperative fasting in adults and children: guidelines from the European Society of Anaesthesiology. Eur J Anaesthesiol. 2011;28:556–569.
38. Bouvet L, Loubradou E, Desgranges FP, Chassard D. Effect of gum chewing on gastric volume and emptying: a prospective randomized crossover study. Br J Anaesth. 2017;119:928–933.
39. Dawes C, Macpherson LM. Effects of nine different chewing-gums and lozenges on salivary flow rate and pH. Caries Res. 1992;26:176–182.
40. Rosenhek M, Macpherson LM, Dawes C. The effects of chewing-gum stick size and duration of chewing on salivary flow rate and sucrose and bicarbonate concentrations. Arch Oral Biol. 1993;38:885–891.

Supplemental Digital Content

Copyright © 2020 International Anesthesia Research Society