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Year : 2023  |  Volume : 28  |  Issue : 3  |  Page : 227-232

Assessment of gastric residual volume with ultrasound in children at fasting and after oral intake of carbohydrate-rich fluid in the preoperative period

1 Department of Anaesthesiology and Intensive Care, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
2 Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
3 Department of Paediatric Surgical Super-Specialities, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Date of Submission29-Aug-2022
Date of Decision17-Jan-2023
Date of Acceptance04-Feb-2023
Date of Web Publication02-May-2023

Correspondence Address:
Aarti Agarwal
Type 5, House No. 3, New Campus, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow - 226 014, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiaps.jiaps_121_22

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Purpose: Despite standard preoperative fasting guidelines, children are subjected to prolonged fasting due to various reasons. This does not reduce gastric residual volume (GRV) further, instead causes hypoglycemia, hypovolemia, and unnecessary discomfort. We calculated the cross-sectional area (CSA) of antrum and GRV in children in fasting state and 2 h after intake of oral carbohydrate-rich fluid, using gastric ultrasound.
Methods: Anteroposterior and craniocaudal gastric antral diameters were measured by ultrasonography in the right lateral decubitus position, at fasting and at 2 h after 8 ml/kg of pulp-free fruit juice ingestion. CSA of antrum and GRV was calculated using validated mathematical models.
Results: Data of 149 children of age >1–12 years were analyzed. Greater than ninety-nine percent of children emptied ≥95% of the ingested pulp-free fruit juice volume within 2 h. One hundred and seven (71.8%) children had reduced CSA and GRV at 2 h after fruit juice ingestion (2.01 ± 1.00 cm2 and 7.77 ± 6.81 ml) as compared to fasting state (3.18 ± 1.40 cm2 and 11.89 ± 7.80 ml). Fourty-nine (28.2%) children had slightly increased CSA and GRV at 2 h after fruit juice (2.46 ± 1.14 cm2 and 10.61 ± 7.26 ml) than at fasting (1.89 ± 0.92 cm2 and 8.61 ± 6.75 ml), but this increased GRV was grossly lower than limit of risk stomach (26.54 ± 8.95 ml).
Conclusion: Carbohydrate-rich drink in the form of pulp-free fruit juice may be safely permitted up to 2 h before anesthetic induction, as it promoted gastric emptying in ≈ 72% of children and 28% of children, although GRV was slightly higher at 2 h after fruit juice ingestion than fasting but remained considerably lower than limit of risk stomach.

Keywords: Gastric antrum, gastric residual volume, gastric ultrasound, preoperative fasting, risk stomach

How to cite this article:
Garg KK, Agarwal A, Goyal P, Lal H, Prasad R, Dhiraaj S, Pant KC, Lal R. Assessment of gastric residual volume with ultrasound in children at fasting and after oral intake of carbohydrate-rich fluid in the preoperative period. J Indian Assoc Pediatr Surg 2023;28:227-32

How to cite this URL:
Garg KK, Agarwal A, Goyal P, Lal H, Prasad R, Dhiraaj S, Pant KC, Lal R. Assessment of gastric residual volume with ultrasound in children at fasting and after oral intake of carbohydrate-rich fluid in the preoperative period. J Indian Assoc Pediatr Surg [serial online] 2023 [cited 2023 May 31];28:227-32. Available from: https://www.jiaps.com/text.asp?2023/28/3/227/375516

   Introduction Top

The American Society of Anesthesiologists (ASA) current practice guidelines for preoperative fasting in children and infants recommend the following: at least 2 h of fasting for clear liquids; 4 h for breast milk; 6 h for infant formula, nonhuman milk, and light meals; and 8 h for fatty foods.[1] This duration of fasting ensures to minimize the risk of pulmonary aspiration which is one of the leading causes of anesthesia-related morbidity and mortality. Risk of pulmonary aspiration is directly related to gastric residual volume (GRV) at the time of anesthetic induction.[2],[3] It is difficult for children to adhere to these guidelines. Reduced hours of fasting may cause risk of aspiration, whereas increased hours of fasting may cause hypoglycemia and hypotension[4] owing to quick dehydration in children.

Literature suggests that preoperative oral carbohydrate on the day of surgery prevent episodes of hypoglycemia and hypotension and favor positive behavior[5] but its impact on GRV and hence its safety from aspiration is still under research.[6]

Our hypothesis is that ingestion of oral carbohydrate-rich fluid would facilitate gastric emptying and would lead to lesser GRV as compared to that after 8 h of fasting.

Therefore, we conducted this study to assess GRV in fasting pediatric patients and compared it with that at 2 h after ingestion of carbohydrate-rich fluid, using bedside gastric ultrasound.

   Material and Method Top

It was a hospital-based cross-sectional, observational study, conducted in a tertiary care medical institute from September 2017 to August 2019. Approval from the institute ethics committee (IEC reference no. 2017-106-MD-97) and written informed consent from parents/guardians of children were taken before enrollment. Pediatric patients of both genders, of the age group >1–12 years, belonging to ASA physical classes 1 and 2, scheduled for elective pediatric surgical procedures under general anesthesia were included in the study. Patients with a history of esophageal or gastric surgery or those having gastrointestinal disorders that delay gastric emptying (such as gastrointestinal obstruction and gastroesophageal reflux) or any systemic disease causing delayed gastric emptying such as diabetes mellitus or electrolyte imbalance were excluded from the study. All emergency cases were also excluded from the study protocol.

Sample size estimation

While assuming that the percentage change in the mean and standard deviation of GRV before and after ingestion of fruit juice would be 10 and 30, respectively, the sample size was found to be 144 with 99% power of the study.

The study was conducted on a day before the planned date of elective surgery, so as to avoid any possible interference by the study protocol in operating schedule of the day.

Steps of the study protocol were as follows:

  1. All eligible children were requested for 8 h of standard fasting overnight
  2. 1st ultrasonography (USG) scan of the gastric antrum was done in fasting state (at 8 h from meal taken at previous night) and was performed in early morning at bedside (before breakfast so as to avoid any discomfort to the child) to calculate cross-sectional area (CSA) of the gastric antrum and GRV
  3. Thereafter, all children were allowed to drink 8 ml/kg of carbohydrate-rich fluid in the form of pulp-free apple juice
  4. 2nd USG scan of the gastric antrum was done after 2 h of fluid ingestion, again to calculate CSA and GRV
  5. CSA and GRV after 1st scan were compared with that after 2nd scan
  6. All children served their own control as their 8 h fasting scans were compared with that at 2 h after fruit juice.

Previous studies have allowed oral liquids in the range of 7–10 ml/kg.[3],[7] We found that children were able to drink 8 ml/kg of fluid easily, hence this volume of oral liquid was allowed in our study.

Scanning technique

Minimal or nil gastric contents are expected after 8 h of fasting in children with normal gastrointestinal physiology. The antrum is the most dependent part of the stomach in the right lateral decubitus (RLD). Thus, we performed gastric scan of children in RLD [Figure 1]a as it is the best position to assess even the smallest gastric volumes.[8] The gastric antrum was imaged with a linear high-frequency transducer (4–12 MHz), in a sagittal or parasagittal plane between the left lobe of the liver and pancreas, just above the level of the aorta or inferior vena cava [Figure 1]b. The transducer was tilted and rotated perpendicular to the long axis of the antrum to obtain a true cross-sectional view of the antrum. Craniocaudal (CC) and anteroposterior (AP) diameters of the antrum were measured after freezing frame between peristaltic contractions and by avoiding respiratory effects [Figure 1]c. The gastric antrum has an elliptical shape and its CSA was calculated by standard formula of surface area of an ellipse; CSA = (AP × CC × π)/4.[9] After measurement in fasting state, children were given 8 ml/kg of pulp-free apple juice to drink. Second ultrasound assessment of CSA of the antrum was performed 2 h after ingestion of pulp-free fruit juice.
Figure 1: (a) Gastric ultrasound of a child being performed in RLD position using high-frequency linear transducer, (b) Empty gastric antrum (A) seen with mucosal folds below left lobe of the liver (L) and just above the level of the aorta (Ao), (c) CC diameter (A-A) and AP diameter (B-B) of elliptical-shaped gastric antrum. RLD: Right lateral decubitus, CC: Craniocaudal, AP: Anteroposterior

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GRV was calculated both for fasting state as well as for 2 h after ingestion of fruit juice, using mathematical model derived and approved by Spencer et al.;[10] GRV (ml) = −7.8+ (3.5 × RLD CSA) + (0.127) × age (months) (RLD CSA is CSA of the gastric antrum in RLD position).

Satisfaction score of parent/child for relief of thirst and hunger as well as overall satisfaction was evaluated using the 1–10 visual analog scale, horizontal, graded, and anchored at both ends, with 1 as not at all satisfied and 10 as most satisfied. Parents were also asked if they would prefer to provide carbohydrate-rich fluid (pulp-free fruit juice) to their children before surgery, if permissible.

Statistical analysis

Paired sample t-test was used to compare the values of CSA and GRV between fasting and 2 h postfruit juice ingestion as well as to compare them with values of GRV considered as risk stomach. The Pearson correlation coefficient was used to find out any association between age and gastric emptying. One-way analysis of variance (ANOVA) test was utilized to find out any difference in gastric emptying between underweight and normal-weight children. P < 0.05 was considered as statistically significant. Statistical package for the Social Sciences, version 23 (SPSS-23, IBM, Chicago, USA) was used for the data analysis.

   Results Top

Out of 166 patients enrolled, data of 149 patients were analyzed finally. Consort diagram in [Figure 2] shows enrollment and exclusion from the study. No solid contents were visualized in any patient during USG either at the time of 1st or 2nd scan.
Figure 2: CONSORT flow diagram of the study showing enrollment and exclusion of patients from the study

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The mean age of the children in the study cohort was 70.1 months (range 22–143 months) with 96 male and 53 female children. The mean body weight was 17.21 kg (range 10–30 kg).

The mean antral CSA and mean GRV of the entire study cohort at 2nd scan were significantly lower than that at 1st scan indicating that both CSA and GRV were reduced significantly at 2 h after fruit juice, as compared to fasting state [Table 1]. Second scan demonstrated that all patients except one had >95% gastric emptying of the fruit juice within 2 h. Gastric emptying was >100% in 71.8% of patients, and in 27.5% of patients, the gastric emptying was >97.0%. In one patient, the emptying was 90.2%.
Table 1: Comparison of cross-sectional area of gastric antrum and gastric residual volume at 1st scan (8 h of fasting) and at 2nd scan (2 h after fruit juice intake) in all patients (n=149)

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CSA and GRV were decreased at 2nd scan in comparison to 1st scan in 107 children (71.8%, subgroup 1) [Table 2], whereas increased at 2nd scan in remaining 42 children (28.2%, subgroup 2) [Table 2]. Despite being statistically significant, quantum of this higher GRV in subgroup 2 was very small and may not of any clinical importance.
Table 2: Cross-sectional area of gastric antrum and gastric residual volume in two subgroups of patients at 1st and 2nd scan

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Literature suggests that GRV of >1.5 ml/kg (risk stomach value) increases the risk of pulmonary aspiration.[11],[12] GRV at 2 h after fruit juice in subgroup 1 and 2 was 0.41 ± 0.27 ml/kg and 0.55 ± 0.29 ml/kg, respectively. It was grossly lower than the value of risk stomach in both subgroups [Table 2].

Strength of linear association between age and gastric emptying was studied and a weak negative correlation could be demonstrated between them, which was statistically insignificant (r = −0.128, P > 0.05, Pearson correlation coefficient). There was no significant difference in gastric emptying between underweight and normal-weight children (P > 0.05, one-way ANOVA).

The median satisfaction score for relief of thirst, hunger, and overall satisfaction was eight. About 94.6% of parents said that they would prefer to provide fruit juice to their child before surgery to reduce thirst and hunger if it becomes permissible.

   Discussion Top

The mean CSA of the gastric antrum and GRV were reduced significantly 2 h post fruit juice ingestion when compared to fasting state in our study, indicating that ingestion of carbohydrate-rich fluid promotes gastric emptying. Song et al. have also administered carbohydrate drink to 79 children and found that the mean CSA of the gastric antrum is reduced significantly as compared to that of a fasting state.[7] They did not measure GRV as calculated in our study. Gomes et al. have also evaluated GRV by USG in 20 healthy adults after drinking carbohydrate-rich fluid and demonstrated that GRV at 2 h after drinking liquid was not significantly different from fasting state.[13] All these data indicate that carbohydrate-rich drinks up to 2 h before surgery do not alter the GRV significantly.

CSA of the gastric antrum has correlated well with GRV in various studies. Spencer et al. measured gastric antral area by sonography in 100 children and found that it correlated well with endoscopically suctioned gastric volumes.[10] Bouvet et al. measured CSA of the gastric antrum in 180 patients and correlated it with gastric volume suctioned with the help of gastric tube.[14] They also found good correlation between the two.

In our study, we divided patients into two subgroups based on the fact that whether their gastric emptying was promoted by carbohydrate-rich fluid or not. We found that 71.8% of children had reduced GRV at 2 h post feed as compared to fasting state (enhanced emptying), whereas only 28.2% of children had increased GRV at 2 h post feed compared to fasting. The increased GRV was statistically significant in the second subgroup but the mean value of this increase was only 2 ml, which may not of much clinical significance. We could not find any other study in literature which has reported similar findings. Increased GRV at 2 h post feed in the smaller subset of patients could be because of greater variability of gastric emptying reported in literature. Salivary secretions up to 1 ml/kg/h and gastric secretions up to 0.6 ml/kg/h contribute to GRV, but values of GRV in our study group are well below “risk stomach” values of 1.5 ml/kg.[11],[12]

No significant correlation between age and gastric emptying was found in our study cohort. Previous studies have also shown no effect of age on gastric emptying time when analyzing the sample population of 5–16 years of age[15] and newborn to 18 years of age.[16] Kwatra et al. studied gastric emptying of milk in infants and children up to 5 years of age and demonstrated faster gastric emptying in infants of 0–6 months of age, as compared to older children,[17] but unlike them, we have not included infants in our study. Aqueous solutions, like pulp-free apple juice fed in our study, have been shown to have faster gastric emptying than other types of liquid and solid meals.[16]

Possible limitations of the study; first, the absence of serial USG scan at 1 h and 3 h especially in subgroup 2 patients, who had increased GRV at 2 h post feed as compared to fasting state, which might have provided further information about gastric emptying in these children. Second, blood glucose levels at fasting and at 2 h after fruit juice, if measured, could have provided insight on trends of blood sugar levels and could have demonstrated possible hypoglycemia after fasting in these children.

   Conclusion Top

General perception is that the prolonged fasting reduces GRV. However, our study demonstrates that carbohydrate-rich fluid given 2 h prior led to lesser GRV in comparison to that achieved after 8 h of fasting. As health-care professionals involved in perioperative care ensure 8 h of fasting, a consensus may be drawn toward the fact that they should also ensure administering oral carbohydrate-rich fluid 2 h before surgery. This will not only aid in reducing the fasting GRV further but may also help in avoiding ill effects of prolonged fasting in children.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: Application to healthy patients undergoing elective procedures: An updated report by the American society of anesthesiologists task force on preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration. Anesthesiology 2017;126:376-93.  Back to cited text no. 1
Benini L, Sembenini C, Heading RC, Giorgetti PG, Montemezzi S, Zamboni M, et al. Simultaneous measurement of gastric emptying of a solid meal by ultrasound and by scintigraphy. Am J Gastroenterol 1999;94:2861-5.  Back to cited text no. 2
Schmitz A, Kellenberger CJ, Liamlahi R, Studhalter M, Weiss M. Gastric emptying after overnight fasting and clear fluid intake: A prospective investigation using serial magnetic resonance imaging in healthy children. Br J Anaesth 2011;107:425-9.  Back to cited text no. 3
Welborn LG, McGill WA, Hannallah RS, Nisselson CL, Ruttimann UE, Hicks JM. Perioperative blood glucose concentrations in pediatric outpatients. Anesthesiology 1986;65:543-7.  Back to cited text no. 4
Castillo-Zamora C, Castillo-Peralta LA, Nava-Ocampo AA. Randomized trial comparing overnight preoperative fasting period versus oral administration of apple juice at 06:00-06:30 am in pediatric orthopedic surgical patients. Paediatr Anaesth 2005;15:638-42.  Back to cited text no. 5
Kaska M, Grosmanová T, Havel E, Hyspler R, Petrová Z, Brtko M, et al. The impact and safety of preoperative oral or intravenous carbohydrate administration versus fasting in colorectal surgery – A randomized controlled trial. Wien Klin Wochenschr 2010;122:23-30.  Back to cited text no. 6
Song IK, Kim HJ, Lee JH, Kim EH, Kim JT, Kim HS. Ultrasound assessment of gastric volume in children after drinking carbohydrate-containing fluids. Br J Anaesth 2016;116:513-7.  Back to cited text no. 7
Perlas A, Mitsakakis N, Liu L, Cino M, Haldipur N, Davis L, et al. Validation of a mathematical model for ultrasound assessment of gastric volume by gastroscopic examination. Anesth Analg 2013;116:357-63.  Back to cited text no. 8
Bolondi L, Bortolotti M, Santi V, Calletti T, Gaiani S, Labò G. Measurement of gastric emptying time by real-time ultrasonography. Gastroenterology 1985;89:752-9.  Back to cited text no. 9
Spencer AO, Walker AM, Yeung AK, Lardner DR, Yee K, Mulvey JM, et al. Ultrasound assessment of gastric volume in the fasted pediatric patient undergoing upper gastrointestinal endoscopy: Development of a predictive model using endoscopically suctioned volumes. Paediatr Anaesth 2015;25:301-8.  Back to cited text no. 10
Van de Putte P, Perlas A. Ultrasound assessment of gastric content and volume. Br J Anaesth 2014;113:12-22.  Back to cited text no. 11
Mesbah A, Thomas M. Preoperative fasting in children. BJA Educ 2017;17:346-50.  Back to cited text no. 12
Gomes PC, Caporossi C, Aguilar-Nascimento JE, Silva AM, Araujo VM. Residual gastric volume evaluation with ultrasonography after ingestion of carbohydrate- or carbohydrate plus glutamine-enriched beverages: A randomized, crossover clinical trial with healthy volunteers. Arq Gastroenterol 2017;54:33-6.  Back to cited text no. 13
Bouvet L, Mazoit JX, Chassard D, Allaouchiche B, Boselli E, Benhamou D. Clinical assessment of the ultrasonographic measurement of antral area for estimating preoperative gastric content and volume. Anesthesiology 2011;114:1086-92.  Back to cited text no. 14
Malik R, Srivastava A, Gambhir S, Yachha SK, Siddegowda M, Ponnusamy M, et al. Assessment of gastric emptying in children: Establishment of control values utilizing a standardized vegetarian meal. J Gastroenterol Hepatol 2016;31:319-25.  Back to cited text no. 15
Bonner JJ, Vajjah P, Abduljalil K, Jamei M, Rostami-Hodjegan A, Tucker GT, et al. Does age affect gastric emptying time? A model-based meta-analysis of data from premature neonates through to adults. Biopharm Drug Dispos 2015;36:245-57.  Back to cited text no. 16
Kwatra NS, Shalaby-Rana E, Andrich MP, Tsai J, Rice AL, Ghelani SJ, et al. Gastric emptying of milk in infants and children up to 5 years of age: Normative data and influencing factors. Pediatr Radiol 2020;50:689-97.  Back to cited text no. 17


  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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