Abstract
Background and Aims
Patients presenting for endoscopic procedures consuming or having recently consumed hard candy may have their procedures delayed or canceled because of concern for aspiration. Our aim is to determine the time needed after ingestion of hard candy for the safe performance of sedated endoscopy.
Methods
A 2-phase institutional review board–approved study was performed. In phase 1, healthy adults collected their oral secretions before and after ingestion of hard candy to measure the impact of hard candy on saliva production. In phase 2, patients undergoing clinical upper endoscopy were randomized to receive hard candy (HC group) or not receive hard candy (no-HC group) approximately 30 minutes before endoscopy. Blinded endoscopists aspirated gastric fluid immediately after gastric intubation and measured its volume and weight. Participants were assessed for adverse events.
Results
Ten healthy volunteers (6 women; median age, 28 years) were enrolled in phase 1. Saliva production peaked at the collection 10 minutes after initiating hard candy. The mean time from candy completion for saliva production to return to within 10% of unstimulated levels was 32 minutes (standard deviation, 12). In phase 2, 63 participants were randomized and had gastric fluid volumes and weights measured. The mean gastric fluid volume was 23.3 mL in the HC group and 17.6 mL in the no-HC group (P = .21). No adverse events were attributable to study participation.
Conclusions
Our results suggest that endoscopic procedures can be safely performed after ingestion of hard candy and should not be delayed by more than 30 minutes.
Sedated endoscopic procedures are low risk1; however, adverse events do occur.2 Although uncommon, a more serious adverse event is pulmonary aspiration, especially of gastric contents, and guidelines dictate a fasting period before sedation onset to minimize risk.3,4 Although guidelines on solid foods and liquids are clear, guidelines in the United States are ambiguous about the need for a fasting period after chewing gum or ingestion of mints or hard candy.3, 4, 5 The current guidelines of the American Society of Anesthesiology recommend that patients not consume food by mouth for a sufficient time to allow for gastric emptying, including 2 hours of fasting for clear liquids and 6 hours of fasting after a light, solid meal.4 These recommendations are consistent with recommendations of the American Society for Gastrointestinal Endoscopy.5 The European Society of Anesthesiology recommendations are clearer with regard to gum and candy, specifically recommending against canceling or delaying a procedure for their use.6
The severity of pulmonary aspiration is associated with multiple factors, including gastric fluid pH, gastric fluid volume, and reduced lower esophageal sphincter tone.7 Gastric fluid volumes of more than 25 mL or .5 mL/kg, and in more recently published data 1.5 mL/kg, are associated with an increased risk for clinically significant pulmonary aspiration.8,9 Elevated intragastric pressure, delayed gastric emptying, and hiatal hernia all increase the likelihood of overcoming resistance at the lower esophageal sphincter and thereby increase the risk for aspiration.7,10 These factors are common in cases of obesity, trauma, and gastric ulcer disease and in delayed gastric emptying from mechanical or GI tract dysmotility.6,11
This research project was contemplated when patients presenting to our endoscopy unit having recently consumed hard candy had their procedures delayed or canceled because of concern for increased risk of pulmonary aspiration. These delays and cancellations affected patient care and patient satisfaction and were of uncertain benefit or need. Therefore, we wanted to determine the time needed, if any, after ingestion of hard candy for the safe performance of sedated endoscopy by measuring salivary secretion and gastric fluid volume and weight after consumption of hard candy.
Methods
Study design and population
This study was conducted in 2 phases, with the first phase conducted in 2020 at the University of Maryland School of Medicine and the second phase conducted at the Baltimore Veterans Affairs Medical Center between 2020 and 2023. Both phases were approved by the Institutional Review Board of the University of Maryland Baltimore (approval nos. HP-0089409 [phase 1] and HP-0089410 [phase 2]), and all participants provided written informed consent. Participants were aged 18 to 89 years and for phase 2 had to be scheduled for a clinical upper endoscopy with moderate sedation. For both phases, exclusion criteria were a history of disorders of saliva production, head and neck cancer, radiation therapy to the head and neck, cognitive impairment, swallowing disorder, previous aspiration, prior gastric surgery, or known gastroparesis/delayed gastric emptying.
Phase 1
Participants in phase 1 were recruited using flyers placed in the gastroenterology and primary care clinics at the University of Maryland Medical Center. Ten healthy adult volunteers were enrolled and were first instructed to take nothing by mouth for 2 hours. They were then asked to lean forward and collect their oral secretions in a series of test tubes with tubes exchanged at 5-minute intervals and saliva volumes and weights measured. After 2 initial 5-minute baseline saliva collections, participants consumed a sugar-free lemon hard candy while continuing to collect saliva samples. This process continued until saliva production returned to below 10% above the average volume of the 2 baseline saliva collections. Mean time to peak saliva production, mean time to return to within 10% of baseline, and greatest time to return to within 10% of baseline saliva production were determined. Participants in phase 1 only were compensated with a $15 gift card for their participation.
Phase 2
This phase was a randomized, controlled, endoscopist-blinded study. Patients scheduled for clinical upper endoscopy with moderate sedation for any indication who met the inclusion and exclusion criteria were enrolled in phase 2. After obtaining informed consent, participants were instructed to select 1 of 3 envelopes presented by a member of the research team. Each envelope contained a note indicating group assignment. These envelopes were prepared and shuffled before the commencement of participant recruitment, and half of the envelopes indicated assignment to each group. Participants were randomized to either receive a sugar-free lemon hard candy (HC group) or not to receive a hard candy (no-HC group) approximately 30 minutes before the initiation of upper endoscopy. The ∼30-minute time frame was chosen based on the results of phase 1, and the estimated time was from start of candy consumption (not time when candy completed).
All participants complied with the endoscopy unit protocol, which requires taking nothing by mouth after the preceding midnight except for small sips of water taken with morning medications. To mimic the typical consumption of such candies, participants in the HC group were asked to let the candies dissolve in their mouths and not to chew. Per our clinical routine, all participants received 4 mL of 4% lidocaine solution to gargle and swallow immediately before administration of sedation. Endoscopists blinded to the study group aspirated the gastric fluid immediately after gastric intubation using the suction feature of the endoscope with an aspiration trap placed in line between the endoscope and the tubing connecting the endoscope to a wall-mounted suction. The aspiration traps used had volume indicators that permitted measurement of volume, and fluid weight was measured using a scientific scale that was tared using an empty aspiration trap. All participants were assessed for adverse events, and demographic and clinical information was recorded.
Statistical analysis
Descriptive statistics were used for phase 1. For phase 2, the study groups were compared on both quantitative and qualitative variables using the Welch t-test and Fisher exact test, respectively. Univariate mixed generalized linear models using Gaussian distribution were used to assess the relationship between multiple factors and gastric fluid weight. A multivariable mixed generalized linear model with Gaussian distribution was used to generate the model to assess candy consumption as a predictor of fluid weight while controlling for age, body mass index (BMI), and the interaction between BMI and candy consumption. All analyses were performed in R, version 4.0.4, using the “stats,” “vctrs,” and “RVAideMemoire” packages.12, 13, 14
Phase 2 sample size calculation was based on a previous study of gum chewing before endoscopy by Goudra et al.15 They found a gastric fluid volume of .345 mL/kg in gum chewers and .112 mL/kg in nongum chewers, with a difference of 7 mL between the median fluid volume of the 2 groups. Anticipating a similar impact of hard candy as gum on gastric fluid volumes, to identify a significant difference using a statistical power of 80% with an alpha of .05, the calculated sample size required was determined to be 56 participants (28 per group). To account for participants who may withdraw or be excluded, we aimed to enroll a total of 70 participants.
Results
Ten healthy volunteers were enrolled into phase 1 (6 women; median age, 28 years), with sampling of salivary secretions occurring before and every 5 minutes after hard candy consumption. Sampling occurred until an individual’s secretion weight returned to below 10% above baseline (Fig. 1). Saliva production peaked by the collection 10 minutes after initiating hard candy, and most participants (70%) returned to below 10% above baseline by 25 minutes, with 2 participants returning by 30 minutes and 1 taking 50 minutes.
Figure 1.
Saliva weights in grams per 5-minute collection for each subject before and at 5-minutes intervals after hard candy consumption. Time zero reflects the average weight of 2 preingestion collections and the time of initiating hard candy. The horizontal blue line represents the LOESS regression curve fit to the collection weight for all participants, whereas each colored line represents an individual participant. Gray shading represents the standard error for the curve.
Seventy participants were enrolled into phase 2, with 7 participants excluded (5 did not have samples collected, 1 had a history of head and neck cancer identified after signing consent, and 1 had prior gastric surgery identified during upper endoscopy), resulting in a final cohort of 63 participants. Thirty-two participants were randomized to the HC group, which received hard candy before upper endoscopy, and 31 were randomized to the no-HC group, which did not receive hard candy. Group composition did not differ based on age, sex, ethnicity, race, or smoking status and on diseases for which information was collected, including type 2 diabetes mellitus, hypertension, or rheumatologic, heart, liver, and kidney disease (Table 1). The use of proton pump inhibitors and H2-receptor antagonists was similar between groups. BMI was slightly lower in the no-HC group (28.1 kg/m2 vs 31.5 kg/m2, P = .0329). There were no significant differences in the weight (18.0 g vs 22.8 g, P = .162) (Fig. 2), volume (18.7 mL vs 23.8 mL, P = .224), or volume normalized to patient weight (.22 mL/kg vs .25 mL/kg, P = .511) of gastric fluid collected at the time of upper endoscopy from the no-HC and HC groups, respectively.
Table 1.
Demographic and clinical characteristics of the phase 2 study cohort
| Variable | Total (n = 63) | No candy (n = 31) | Candy (n = 32) | P value |
|---|---|---|---|---|
| Age, y | 58.8 [46-70] (24-88) | 61.0 [54.5-72.0] (24-80) | 56.7 [44.3-67.5] (29-88) | .244 |
| Body mass index, kg/m2 | 29.8 [24.3-34.0] (16.7-44.5) | 28.1 [23.9-31.6] (17.5-42.8) | 31.5 [26.8-35.3] (16.7-44.5) | .0329 |
| Sex | .708 | |||
| Male | 55 (87.3) | 28 (90.3) | 27 (84.4) | |
| Female | 8 (12.7) | 3 (9.68) | 5 (15.6) | |
| Race | .918 | |||
| White | 22 (34.9) | 10 (31.3) | 12 (38.7) | |
| African American | 37 (58.7) | 19 (59.4) | 18 (58.1) | |
| Other/unknown | 4 (6.35) | 2 (6.45) | 2 (6.3) | |
| Ethnicity | .492 | |||
| Not Hispanic | 62 (98.4) | 30 (96.8) | 32 (100) | |
| Hispanic | 1 (1.59) | 1 (3.22) | 0 (0) | |
| Smoking | .291 | |||
| Current | 19 (30.2) | 12 (38.7) | 7 (21.9) | |
| Former | 16 (25.4) | 8 (25.8) | 8 (25.0) | |
| Never | 28 (44.4) | 11 (35.5) | 17 (53.1) | |
| Fluid weight, g | 20.4 [9.45-28.4] (.230-65.4) | 18.0 [8.34-26.7] (.230-43.5) | 22.8 [10.7-30.4] (1.30-65.4) | .162 |
| Fluid volume, mL | 20.9∗ [9.00-29.0] (1.00-70.0) | 18.7 [6.50-27.0] (1.00-53.0) | 23.8∗ [11.3-32.0] (1.00-70.0) | .224 |
| Gastric fluid volume normalized to weight, mL/kg | .24∗ [.10- .32] (.01-.68) | .22 [.08- .32] (.01-.54) | .25∗ [.12- .33] (.01-.68) | .511 |
| Type 2 diabetes mellitus | .572 | |||
| Yes | 17 (27.0) | 7 (22.6) | 10 (31.3) | |
| No | 46 (73.0) | 24 (77.4) | 22 (68.7) | |
| Hypertension | .450 | |||
| Yes | 36 (57.1) | 16 (51.6) | 20 (62.5) | |
| No | 27 (42.9) | 15 (48.4) | 12 (37.5) | |
| Rheumatic disease | .184 | |||
| Yes | 10 (15.9) | 7 (22.6) | 3 (9.38) | |
| No | 53 (84.1) | 24 (77.4) | 29 (90.6) | |
| Proton pump inhibitor use | .211 | |||
| Yes | 32 (50.8) | 13 (41.9) | 19 (59.4) | |
| No | 31 (49.2) | 18 (58.1) | 13 (40.6) | |
| H2-blocker use | ≥.999 | |||
| Yes | 13 (20.6) | 6 (19.4) | 7 (21.9) | |
| No | 50 (79.4) | 25 (80.6) | 25 (78.1) | |
| Heart disease | .196 | |||
| Yes | 5 (7.94) | 4 (12.9) | 1 (3.13) | |
| No | 58 (92.1) | 27 (87.1) | 31 (96.9) | |
| Liver disease | .708 | |||
| Yes | 7 (11.1) | 4 (12.9) | 3 (9.38) | |
| No | 56 (88.9) | 27 (87.1) | 29 (90.6) | |
| Kidney disease | .426 | |||
| Yes | 6 (9.52) | 4 (12.9) | 2 (6.3) | |
| No | 57 (90.5) | 27 (87.1) | 30 (93.7) |
Values are mean [interquartile range] (range) or n (%).
Two unknown.
Figure 2.
Comparison of gastric fluid weights in the hard candy and no-hard candy groups. The horizontal lines represent the mean, boxes represent the 25th-75th interquartile range, and the whiskers represent the 95th percentile values.
A series of univariate generalized linear models looking at clinical variables and their relationship with fluid weight were performed to assess their role as predictors of gastric fluid weight (gastric fluid weight was used for this analysis instead of fluid volume because it was considered more accurate because of the foamy nature of some aspirated gastric fluid specimens); none of the factors assessed had an independent association with gastric fluid weight (Supplementary Table 1, available online at www.igiejournal.org). A mixed linear regression was performed to determine the relationship between candy consumption and gastric fluid weight while controlling for BMI, age, and the interaction between BMI and candy consumption, given the differences in BMI between the 2 groups (Supplementary Table 2, available online at www.igiejournal.org). For this analysis, the interaction variable assessed whether increasing BMI contributes to gastric fluid weight differently in the group that consumed candy (ie, looking at whether those with higher BMIs may produce more gastric secretions specifically after candy consumption) to account for the fact that BMI was significantly higher in the group consuming candy. Even when controlling for these other factors, candy consumption had no significant relationship with gastric fluid weight.
No adverse events related to study participation were identified. One participant in phase 2 developed hypoxia and mental status changes after sample collection and soon after completion of his endoscopic procedure. Given the acuity of the situation, the endoscopist and principal investigator were unblinded and learned that the patient was randomized to the no-HC group. The participant was subsequently diagnosed with an acute pulmonary embolism and recovered. No other unblinding events or adverse events occurred.
Discussion
Current U.S. guidelines do not provide clear recommendations regarding the presedation time requirement after hard candy consumption before sedated endoscopic procedures.4,5 This lack of guidance stems, in part, from a scarcity of relevant studies and has led to a discrepancy in practice, with sedation and anesthesia providers variably treating hard candy as either a solid, a liquid, or as no oral intake, with corresponding differences in recommended fasting intervals. In contrast, the European Society of Anesthesiology suggests that procedures should not be canceled or delayed for gum, candy, or smoking immediately before arrival for a procedure.6
Gastric fluid volume for a fasting patient has been suggested to be .4 mL/kg to 1.2 mL/kg.16 More studies have investigated the effects of chewing gum, specifically sugar-free or nicotine gum, on gastric content, acidity, patient satisfaction, and rate of postoperative adverse events. These studies have had variable findings regarding the amount of gastric fluid collected. A few found increased gastric fluid volumes of more than 25 mL, but others did not show statically significant differences between those who consumed gum and those who did not, and none found an increased rate of pulmonary aspiration.8,15,17, 18, 19, 20
A study by Goudra et al15 included 67 participants who were randomized to either chew gum or not chew gum before sedated endoscopy. The study demonstrated a statistically significant difference between the 2 groups, with the gum chewing group having a median gastric volume of 13 mL compared with 6 mL in the group that did not chew gum. However, it is crucial to note that these low median gastric fluid volumes likely hold low clinical significance.15
There are 2 notable studies on the effect of hard candy on gastric fluid volume: 1 studying lollipop consumption and the other sugar-free candy. Kamalipour et al17 compared patients consuming sugar-free gum, bicarbonate chewing gum, water, and lollipops with control patients undergoing elective surgeries requiring endotracheal intubation. After induction of anesthesia and endotracheal intubation, they collected gastric fluid using an orogastric tube and did not find a statically significant difference in gastric fluid volume between groups, with an average of 27 mL (standard deviation, 5) in the sugar-free gum group, 20 mL (standard deviation, 5) in the lollipop group, and 18 mL (standard deviation, 8) in control subjects.17 Somnuke et al,8 using a study design similar to ours, studied sugar-free hard candy ingestion in a population in Thailand before elective endoscopy and found a statically significant difference in gastric fluid volume, with the candy group having a median gastric fluid volume of 28.5 mL compared with 20.0 mL in the control group. However, when adjusted for weight in mL/kg, this difference became insignificant, with a P value of .120. They found the mean and median gastric fluid volumes for both groups were less than .5 mL/kg, volumes that would not be expected to increase the risk of pulmonary aspiration events. Similar to our study, they reported no candy ingestion–related adverse events.
Our study revealed that saliva production after ingestion of hard candy peaks within 10 minutes and typically returns to baseline production within 30 minutes. We also did not find a statically significant difference in gastric fluid volume (P = .224), gastric fluid volume normalized to patient weight (P = .511), or fluid weight (P = .162) between groups. The strengths of our study include its randomized, endoscopist-blinded design and that samples were collected endoscopically (vs gastric tube), which allows for more accurate sample collection under direct visualization. Inclusion of gastric fluid weight measurements is unique to our study and adds to the strength of our findings because the foamy nature of some gastric aspirates may impact measured volumes. Limitations of our study are that it is a single-center study, lacks fluid pH measurements, and the study setting for phase 2 was a Veterans hospital. Because study participants were predominantly men (87.3%), our results may not be generalizable to women.
In conclusion, we found that saliva production peaks within 10 minutes of consuming hard candy and typically returns to baseline production within 30 minutes. Consumption of hard candy does not significantly impact gastric fluid volume or weight when consumed about 30 minutes before endoscopy. Our results suggest that endoscopic procedures can be safely performed after ingestion of hard candy and suggest these procedures do not need to be delayed by more than 30 minutes after completing ingestion of hard candy.
Patient consent
The patients in this article have given written informed consent to publication of their case details.
Disclosure
All authors disclosed no financial relationships.
Acknowledgments
The following author received research support for this study from an award from the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases (T32 DK067872-19): M. Alizadeh. The study was also supported by departmental/institutional funds.
Footnotes
How to cite iGIE articles: Johnson R, Webber C, Thompson TJ, et al. Article title. IGIE 2023;2:10-26.
Appendix
Supplementary Table 1.
Univariate analyses of the association between demographic and clinical features and fluid weight
| Variable | Fluid weight (g) (n = 63) |
P value |
|---|---|---|
| Age | –.234 | .0904 |
| Body mass index | .00347 | .955 |
| Sex | –.000756 | .979 |
| Race | .00962 | .614 |
| Ethnicity | .108 | .384 |
| Smoking | .0232 | .319 |
| Type 2 diabetes mellitus | .0242 | .249 |
| Hypertension | .00154 | .936 |
| Rheumatic disease | .0236 | .337 |
| Proton pump inhibitor use | –.0152 | .427 |
| H2-blocker use | .00284 | .902 |
| Heart disease | –.000175 | .996 |
| Liver disease | .0217 | .441 |
| Kidney disease | .0103 | .738 |
Generalized linear models of Gaussian (quantitative variables) or binomial (categorical variables) families were used. Fluid weight represents the coefficient value.
Supplementary Table 2.
Penalized quasi-likelihood generalized linear model predicting fluid weight as a function of candy consumption status, age, BMI, and the interaction between BMI and candy consumption
| Variable | β Coefficient (linear effect) | P value |
|---|---|---|
| No candy (relative to candy) | 9.52 | .574 |
| Age | –.195 | .106 |
| BMI | .117 | .754 |
| Interaction between BMI and no candy consumption | –.465 | .404 |
BMI, Body mass index.
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