Preoperative fasting and the risk of pulmonary aspiration-a narrative review of historical concepts, physiological effects, and new perspectives

In the early days of anaesthesia, the fasting period for liquids was kept short. By the mid-20th century 'nil by mouth after midnight' had become routine as the principles of the management of 'full stomach' emergencies were extended to include elective healthy patients. Back then, no distinction was made between the withholding of liquids and solids. Towards the end of the last century, recommendations of professional anaesthesiology bodies began to reduce the fasting time of clear liquids to 2 h. This reduction in fasting time was based on the understanding that gastric emptying of clear liquids is rapid, exponential, and proportional to the current filling state of the stomach. Furthermore, there was no evidence of a link between drinking clear liquids and the risk of aspiration. Indeed, most instances of aspiration are caused by failure to identify aspiration risk factors and adjust the anaesthetic technique accordingly. In contrast, long periods of liquid withdrawal cause discomfort and may also lead to serious postoperative complications. Despite this, more than two decades after the introduction of the 2 h limit, patients still fast for a median of up to 12 h before anaesthesia, mainly because of organisational issues. Therefore, some hospitals have decided to allow patients to drink clear liquids within 2 h of induction of anaesthesia. Well-designed clinical trials should investigate whether these concepts are safe in patients scheduled for anaesthesia or procedural sedation, focusing on both aspiration risk and complications of prolonged fasting.

The relationship between gastric ultrasound findings and endoscopically aspirated volume in infants and determining the antral cutoff value for empty stomach diagnosis

BACKGROUND/AIMS

Pulmonary aspiration of gastric content is a serious perioperative complication. The objective of this prospective study was to assess the relationship between the gastric volumes suctioned endoscopically and quantitative (antral cross-section area) and qualitative (empty vs. nonempty) examination of the gastric antrum. Furthermore, the study aimed to determine the best antral cross-section area cutoff value for a truly empty antrum in infants.

METHODS

This study was performed in a pediatric gastrointestinal endoscopy unit. Antral sonography was performed in supine and right lateral decubitus positions in 46 fasted infants prior to upper gastrointestinal endoscopic evaluation. Antral cross-sectional area measurements in both positions and qualitative evaluation of the antrum (according to a three-point grading system) were recorded. Gastric contents were endoscopically suctioned and measured.

RESULTS

Forty-six patients (aged under 24 months) were included. According to the three-point qualitative grading system, 76.1% of patients were classified as grade 0. The best cutoff value for the antral cross-section area in the right lateral decubitus position, indicating an empty antrum, was determined to be 2.40 cm2. At this specific cutoff value, the sensitivity was 100%, the specificity was 68.6%, and the negative predictive value was 100%.

CONCLUSIONS

Gastric ultrasonography can confirm an empty or nearly empty stomach in healthy infants.

Gastric-filling ultrasonography to evaluate gastric motility in patients with Parkinson's disease

Background

Delayed gastric emptying is a common non-motor symptom of Parkinson's disease (PD). However, there is currently no objective evaluation and diagnostic method for this condition.

Objectives

The purpose of this study was to evaluate the feasibility of gastric-filling ultrasonography for gastric motility in patients with PD and the relationship between gastric dynamics and gastrointestinal symptoms and motor symptoms of PD.

Design setting and patients

We performed a case-control study with 38 patients with PD and 34 healthy controls.

Methods

All patients underwent a 120-min ultrasonography examination using a 500-ml semi-liquid test meal. We determined the antral contraction amplitude (ACA), the antrum contraction frequency (ACF), the motility index (MI), and the gastric antral cross-sectional area (CSA). We acquired the CSA at six time points: fasting for 12 h (T0), immediately after drinking the semi-liquid test meal (T1); and at 30 (T30), 60 (T60), 90 (T90), and 120 (T120) min. We calculated the gastric emptying rate (GER) at different time points by using the CSA. We compared the GER between the groups and evaluated the correlation between the GER and gastrointestinal symptoms and motor symptoms of PD.

Results

The MI and ACF were significantly lower in the PD group compared with the control group (P < 0.05). The GER at T30 and the ACA showed no significant difference between the groups (P > 0.05). At different time points, the GER was significantly different between the PD and control groups (P < 0.001). There was no significant association between the GER and gastrointestinal symptoms; none of them were risk factors for impaired gastric emptying (odds ratio > 1). The GER was negatively correlated with the severity of PD motor symptoms (P < 0.05).

Conclusion

Patients with PD had significantly delayed gastric emptying, which was negatively correlated with the severity of PD motor symptoms. Measuring gastric emptying by gastric-filling ultrasound had good diagnostic value in clinical screening for delayed gastric motility in patients with PD.

Clinical Trial Registration

https://www.chictr.org.cn/showproj.html?proj=126304.

Determining residual gastric volume in healthy children using ultrasound

PURPOSE

Fasting guidelines for children recommend restricting clear fluids for one or two hours before a procedure to reduce pulmonary aspiration. Gastric volumes < 1.5 mL·kg-1 do not seem to present an increased risk of pulmonary aspiration. Our aim was to quantify the time to achieve a gastric volume < 1.5 mL·kg-1 after clear fluid ingestion in children.

METHODS

We conducted a prospective observational study in healthy volunteers aged 1-14 yr. Participants followed American Society of Anesthesiologists fasting guidelines prior to data collection. Gastric ultrasound (US) was performed in the right lateral decubitus (RLD) position to determine the antral cross-sectional area (CSA). Following baseline measurements, participants consumed 250 mL of a clear fluid. We then performed gastric US at four time intervals: 30, 60, 90, and 120 min. Data were collected following a predictive model for gastric volume estimation using the formula: volume (mL) = -7.8 + (3.5 × RLD CSA) + (0.127) × age (months).

RESULTS

We recruited 33 healthy children aged 2-14 yr. The mean gastric volume per weight (mL·kg-1) at baseline was 0.51 mL·kg-1 (95% confidence interval [CI], 0.46 to 0.57). The mean gastric volume was 1.55 mL·kg-1 (95% CI, 1.36 to 1.75) at 30 min, 1.17 mL·kg-1 (95% CI, 1.01 to 1.33) at 60 min, 0.76 mL·kg-1 (95% CI, 0.67 to 0.85) at 90 min, and 0.58 mL·kg-1 (95% CI, 0.52 to 0.65) at 120 min.

CONCLUSION

Our results show that total gastric fluid volume was < 1.5 mL·kg-1 after 60 min, suggesting that current fasting guidelines for children could be liberalized.

Ultrasound Assessment of Gastric Fluid Volume in Children Scheduled for Elective Surgery After Clear Fluid Fasting for 1 Versus 2 Hours: A Randomized Controlled Trial

BACKGROUND

This study aimed to compare the gastric fluid volume (GFV) in children who fasted 1 versus 2 hours using ultrasound, after ingestion of a defined volume of clear fluid.

METHODS

Children scheduled for elective surgery were enrolled in this randomized, double-blinded, controlled trial. After receiving 3 mL kg -1 clear fluid, participants were randomized to have a gastric ultrasound after fasting for either 1 hour (1-hour group, n = 116) or 2 hours (2-hour group, n = 111). Our primary outcome was the GFV. Other outcomes included the antral cross-sectional area, frequency of high risk and low risk of aspiration, and qualitative grading for the gastric antrum.

RESULTS

Two hundred and twenty-seven children were available for final analysis. The median (Q1-Q3) GFV was higher in the 1-hour group versus the 2-hour group (0.61 [0.41-0.9] mL kg -1 vs 0.32 [0.23-0.47] mL kg -1 ; P value = .001). None of the study groups had GFV ≥1.5 mL kg -1 . The frequency (%) of GFV ≥1.25 mL kg -1 was comparable between both groups (2 [1.7%] vs 0 [0%], P value = .165). However, the frequency of GFV ≥0.8 mL kg -1 was higher in 1-hour group than in 2-hour group (34.5% vs 4.5%), and grade 2 antral grading score was 56.9% in 1-hour group vs 0.9% in 2-hour group ( P value <.001).

CONCLUSIONS

In healthy children scheduled for elective surgery receiving 3 mL kg -1 clear fluid, the median GFV after 1-hour fasting was double the volume after conventional 2-hour fasting. These findings should be considered whether weighting the risk/benefit of a liberal approach to preoperative fasting versus the risk of pulmonary aspiration.

2023 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting: Carbohydrate-containing Clear Liquids with or without Protein, Chewing Gum, and Pediatric Fasting Duration-A Modular Update of the 2017 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting

These practice guidelines are a modular update of the "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." The guidance focuses on topics not addressed in the previous guideline: ingestion of carbohydrate-containing clear liquids with or without protein, chewing gum, and pediatric fasting duration.

Gastric Point-of-Care Ultrasound in Acutely and Critically Ill Children (POCUS-ped): A Scoping Review

Introduction

Point-of-care ultrasound (POCUS) use is increasing in pediatric clinical settings. However, gastric POCUS is rarely used, despite its potential value in optimizing the diagnosis and management in several clinical scenarios (i.e., assessing gastric emptying and gastric volume/content, gastric foreign bodies, confirming nasogastric tube placement, and hypertrophic pyloric stenosis). This review aimed to assess how gastric POCUS may be used in acute and critically ill children.

Materials and Methods

An international expert group was established, composed of pediatricians, pediatric intensivists, anesthesiologists, radiologists, nurses, and a methodologist. A scoping review was conducted with an aim to describe the use of gastric POCUS in pediatrics in acute and critical care settings. A literature search was conducted in three databases, to identify studies published between 1998 and 2022. Abstracts and relevant full texts were screened for eligibility, and data were extracted, according to the JBI methodology (Johanna Briggs Institute).

Results

A total of 70 studies were included. Most studies (n = 47; 67%) were conducted to assess gastric emptying and gastric volume/contents. The studies assessed gastric volume, the impact of different feed types (breast milk, fortifiers, and thickeners) and feed administration modes on gastric emptying, and gastric volume/content prior to sedation or anesthesia or during surgery. Other studies described the use of gastric POCUS in foreign body ingestion (n = 6), nasogastric tube placement (n = 5), hypertrophic pyloric stenosis (n = 8), and gastric insufflation during mechanical ventilatory support (n = 4). POCUS was performed by neonatologists, anesthesiologists, emergency department physicians, and surgeons. Their learning curve was rapid, and the accuracy was high when compared to that of the ultrasound performed by radiologists (RADUS) or other gold standards (e.g., endoscopy, radiography, and MRI). No study conducted in critically ill children was found apart from that in neonatal intensive care in preterms.

Discussion

Gastric POCUS appears useful and reliable in a variety of pediatric clinical settings. It may help optimize induction in emergency sedation/anesthesia, diagnose foreign bodies and hypertrophic pyloric stenosis, and assist in confirming nasogastric tube placement, avoiding delays in obtaining confirmatory examinations (RADUS, x-rays, etc.) and reducing radiation exposure. It may be useful in pediatric intensive care but requires further investigation.

Ultrasound-Determined Residual Gastric Volume after Clear-Fluid Ingestion in the Paediatric Population: Still a Debatable Issue

Background: Current fasting guidelines are often exceeded in clinical practice, resulting in stressful events during anaesthesia in children. This prospective study compares residual gastric volume after 1 versus 2 h of clear fluid ingestion in fasted children. METHODS: A total of 106 patients were enrolled in the study. Ultrasonography (USG) of gastric antrum (GA) was performed in the supine and right lateral decubitus (RLD) positions. All children fasted from solid food for 6 h. Blackcurrant flavoured drink (3 mL/kg) was given following the measurement of baseline (T0) USG of GA, with follow-ups after 1 (T1) and 2 (T2) hours post-ingestion. Residual gastric volume (RGV) was calculated from the cross-sectional area of GA using a standard formula. Parental satisfaction with their children’s behaviour concerning fasting time was recorded. Results: RGV was significantly higher at T1 compared to T2 (p < 0.001). No significant difference was seen between T0 and T2 (p = 0.30). Parental satisfaction was similar at T1 and T2 (p = 0.158). Conclusions: The RGV in paediatric patients after 1 h of clear fluid ingestion was significantly higher than after 2 h of ingestion. There was no difference observed in parental satisfaction concerning the two intervals of fluid fasting. RLD and supine positions can be used reliably to measure the RGV in children.

Examining the Role of Food Form on Children's Self-Regulation of Energy Intake

Increasing childhood obesity rates in both the United States and worldwide demonstrate a need for better prevention and intervention strategies. However, little is understood about what factors influence children's ability to sense and respond to hunger and fullness cues, a critical component of self-regulation of energy intake and maintenance of a healthy body weight. Research in adults suggests that food form may influence self-regulation of energy intake. More specifically, beverages are not as satiating as solid foods when matched for factors such as energy content, energy density, and volume and therefore elicit poorer energy intake self-regulation. However, much less is known about the impact of food form on children's ability to regulate their energy intake. This report describes a study that will examine the relationship between biological, cognitive, and psychological factors and children's appetite self-regulation (ASR). In this registered report, we will examine the influence of food form on children's short-term energy compensation, a proxy indicator of energy intake self-regulation. The study will employ a within-subjects, crossover design in which children (n = 78) ages 4.5-6 years will attend five laboratory visits, each ~1 week apart. During each visit, children will be presented with one of five possible preload conditions: apple slices, apple sauce, apple juice, apple juice sweetened with non-nutritive sweetener (NNS), or no preload. The order of preload conditions will be pseudorandomized and counterbalanced across participants. Following consumption of the preload (or no preload), children will consume a standardized ad libitum test meal of common foods for this age group. We hypothesize that children will demonstrate poorer short-term energy compensation (greater meal intake) in response to the liquid and semi-solid preloads compared to the solid preload. Understanding how energy in various forms affects children's ability to self-regulate intake has implications for dietary recommendations and will help identify those who are most at-risk for poor intake regulation and the development of obesity.

Review of paediatric gastrointestinal physiology relevant to the absorption of orally administered medicines

Despite much progress in regulations to improve paediatric drug development, there remains a significant need to develop better medications for children. For the design of oral dosage forms, a detailed understanding of the specific gastrointestinal (GI) conditions in children of different age categories and how they differ from GI conditions in adults is essential. Several review articles have been published addressing the ontogeny of GI characteristics, including luminal conditions in the GI tract of children. However, the data reported in most of these reviews are of limited quality because (1) information was cited from very old publications and sometimes low quality sources, (2) data gaps in the original data were filled with textbook knowledge, (3) data obtained on healthy and sick children were mixed, (4) average data obtained on groups of patients were mixed with data obtained on individual patients, and (5) results obtained using investigative techniques that may have altered the outcome of the respective studies were considered. Consequently, many of these reviews draw conclusions that may be incorrect. The aim of the present review was to provide a comprehensive and updated overview of the available original data on the ontogeny of GI luminal conditions relevant to oral drug absorption in the paediatric population. To this end, the PubMed and Web of Science metadatabases were searched for appropriate studies that examined age-related conditions in the oral cavity, esophagus, stomach, small intestine, and colon. Maturation was observed for several GI parameters, and corresponding data sets were identified for each paediatric age group. However, it also became clear that the ontogeny of several GI traits in the paediatric population is not yet known. The review article provides a robust and valuable data set for the development of paediatric in vitro and in silico biopharmaceutical tools to support the development of age-appropriate dosage forms. In addition, it provides important information on existing data gaps and should provide impetus for further systematic and well-designed in vivo studies on GI physiology in children of specific age groups in order to close existing knowledge gaps and to sustainably improve oral drug therapy in children.

Pre-operative fasting in children: A guideline from the European Society of Anaesthesiology and Intensive Care

Current paediatric anaesthetic fasting guidelines have recommended conservative fasting regimes for many years and have not altered much in the last decades. Recent publications have employed more liberal fasting regimes with no evidence of increased aspiration or regurgitation rates. In this first solely paediatric European Society of Anaesthesiology and Intensive Care (ESAIC) pre-operative fasting guideline, we aim to present aggregated and evidence-based summary recommendations to assist clinicians, healthcare providers, patients and parents. We identified six main topics for the literature search: studies comparing liberal with conservative regimens; impact of food composition; impact of comorbidity; the use of gastric ultrasound as a clinical tool; validation of gastric ultrasound for gastric content and gastric emptying studies; and early postoperative feeding. The literature search was performed by a professional librarian in collaboration with the ESAIC task force. Recommendations for reducing clear fluid fasting to 1 h, reducing breast milk fasting to 3 h, and allowing early postoperative feeding were the main results, with GRADE 1C or 1B evidence. The available evidence suggests that gastric ultrasound may be useful for clinical decision-making, and that allowing a 'light breakfast' may be well tolerated if the intake is well controlled. More research is needed in these areas as well as evaluation of how specific patient or treatment-related factors influence gastric emptying.

Pro-Con Debate: 1- vs 2-Hour Fast for Clear Liquids Before Anesthesia in Children

Perioperative fasting guidelines are designed to minimize the risk of pulmonary aspiration of gastrointestinal contents. The current recommendations from the American Society of Anesthesiologists (ASA) and the European Society of Anaesthesiology and Intensive Care (ESAIC) are for a minimum 2-hour fast after ingestion of clear liquids before general anesthesia, regional anesthesia, or procedural sedation and analgesia. Nonetheless, in children, fasting guidelines also have consequences as regards to child and parent satisfaction, hemodynamic stability, the ability to achieve vascular access, and perioperative energy balance. Despite the fact that current guidelines recommend a relatively short fasting time for clear fluids of 2 hours, the actual duration of fasting time can be significantly longer. This may be the result of deficiencies in communication regarding the duration of the ongoing fasting interval as the schedule changes in a busy operating room as well as to poor parent and patient adherence to the 2-hour guidelines. Prolonged fasting can result in children arriving in the operating room for an elective procedure being thirsty, hungry, and generally in an uncomfortable state. Furthermore, prolonged fasting may adversely affect hemodynamic stability and can result in parental dissatisfaction with the perioperative experience. In this PRO and CON presentation, the authors debate the premise that reducing the nominal minimum fasting time from 2 hours to 1 hour can reduce the incidence of prolonged fasting and provide significant benefits to children, with no increased risks.

Ultrasound imaging for assessing functions of the GI tract

OBJECTIVE

In the following review we outline how ultrasound can be used to measure physiological processes in the gastrointestinal tract.

APPROACH

We have investigated the potential of ultrasound in assessing gastrointestinal physiology including original research regarding both basic methodology and clinical applications.

MAIN RESULTS

Our main findings show the use of ultrasound to study esophageal motility, measure volume and contractility of the stomach, assess motility, wall thickness, and perfusion of the small bowel, and evaluate wall vascularization and diameters of the large bowel.

SIGNIFICANCE

Ultrasound is a widely accessible technology that can be used for both scientific and clinical purposes. Being radiation-free and user friendly, the examination can be frequently repeated enabling longitudinal studies. Furthermore, it does not influence normal GI physiology, thus being useful to estimate motility and subtle changes in physiology. Accordingly, ultrasound scanning and physiological measurements may make a big difference for the scientist and the doctor; and for the patients who receive an efficient work-up.

Ultrasound assessment of gastric emptying time after intake of clear fluids in children scheduled for general anesthesia-A prospective observational study

BACKGROUND

While many clinics have changed their local regimen toward a more liberal policy regarding clear fluid fasting for general anesthesia, there is a lack of studies evaluating gastric emptying time in a clinical setting.

AIMS

Based on this and before implementation of a more liberal preoperative clear fluid fasting policy for children, we studied gastric emptying time of clear fluids in children and hypothesized that the mean gastric emptying time would be 1 hour.

METHODS

Between March and December 2019, children scheduled for general anesthesia at our University Children's Hospital were enrolled in this prospective observational study. After overnight fasting, gastric emptying was examined by sonographic measurements of the gastric antral area before and 5, 15, 30, 45, and 60 minutes after intake of water or fruit juice.

RESULTS

Twenty-six children were enrolled in this study, and 24 aged 11 (range 4-17) years were included for statistical analysis. The median ingested fluid volume was 4.7 (range 1.8-11.8) mL kg^-1 . The gastric antral area of the children initially increased and subsequently decreased after intake of clear fluids and correlated significantly with fasting time (r = -0.55, P < .0001). After 1 hour, the gastric antral area had returned to the baseline level in 20 children but not in four children with a fluid intake >5 mL kg^-1 . There was no difference in the gastric antral area between water and fruit juice. Using a linear regression model, the calculated mean gastric emptying time of clear fluids was 52 minutes.

CONCLUSION

This study showed that the gastric emptying time of children after intake up to 5 mL kg^-1 clear fluids was <1 hour in a clinical setting. These results support the more liberal fasting regimen favoring a 1-hour fasting time and suggest 5 mL kg^-1 as an upper limit for clear fluids (eg, water, sugared water or tea or diluted fruit juice) from 2 hours to 1 hour before induction of anesthesia in children.

Impact of clear fluid fasting on pulmonary aspiration in children undergoing general anesthesia: Results of the German prospective multicenter observational (NiKs) study

BACKGROUND

A preliminary national audit of real fasting times including 3324 children showed that the fasting times for clear fluids and light meals were frequently shorter than recommended in current guidelines, but the sample size was too small for subgroup analyses.

AIMS

Therefore, the primary aim of this extended study with more participating centers and a larger sample size was to determine whether shortened fasting times for clear fluids or light meals have an impact on the incidence of regurgitation or pulmonary aspiration during general anesthesia in children. The secondary aim was to evaluate the impact of age, emergent status, ASA classification, induction method, airway management or surgical procedure.

METHODS

After the Ethics Committee's approval, at least more than 10 000 children in total were planned to be enrolled for this analysis. Patient demographics, real fasting times, anesthetic and surgical procedures, and occurrence of target adverse events defined as regurgitation or pulmonary aspiration were documented using a standardized case report form.

RESULTS

At fifteen pediatric centers, 12 093 children scheduled for surgery or interventional procedures were included between October 2018 and December 2019. Fasting times were shorter than recommended in current guidelines for large meals in 2.5%, for light meals in 22.4%, for formula milk in 5.3%, for breastmilk in 10.9%, and for clear fluids in 39.2%. Thirty-one cases (0.26%) of regurgitation, ten cases (0.08%) of suspected pulmonary aspiration, and four cases (0.03%) of confirmed pulmonary aspiration were reported, and all of them recovered quickly without any consequences. Fasting times for clear fluids shortened from 2 hours to 1 hour did not affect the incidence of adverse events (upper limit 95% CI 0.08%). The sample size of the cohort with fasting times for light meals shorter than 6 hours was too small for a subgroup analysis. An age between one and 3 years (odds ratio 2.7,95% CI 1.3 to 5.8%; P < .01) and emergent procedures (odds ratio 2.8,95% CI 1.4 to 5.7;P < .01) increased the incidence of adverse events, whereas ASA classification, induction method, or surgical procedure had no influence. The clear fluid fasting times were shortest under 6/4/0 as compared to 6/4/1 and 6/4/2 fasting regimens, all with an incidence of 0.3% for adverse events.

CONCLUSION

This study shows that a clear fluid fasting time shortened from 2 hours to 1 hour does not affect the incidence of regurgitation or pulmonary aspiration, that an age between one and 3 years and emergent status increase the incidence of regurgitation or pulmonary aspiration, and that pulmonary aspiration followed by postoperative respiratory distress is rare and usually shows a quick recovery.

Preoperative Fluid Fasting Times and Postinduction Low Blood Pressure in Children

Background

Children are required to fast before elective general anesthesia. This study hypothesized that prolonged fasting causes volume depletion that manifests as low blood pressure. This study aimed to assess the association between fluid fasting duration and postinduction low blood pressure.

Methods

A retrospective cohort study was performed of 15,543 anesthetized children without preinduction venous access who underwent elective surgery from 2016 to 2017 at Children’s Hospital of Philadelphia. Low blood pressure was defined as systolic blood pressure lower than 2 standard deviations below the mean (approximately the 2.5th percentile) for sex- and age-specific reference values. Two epochs were assessed: epoch 1 was from induction to completion of anesthesia preparation, and epoch 2 was during surgical preparation.

Results

In epoch 1, the incidence of low systolic blood pressure was 5.2% (697 of 13,497), and no association was observed with the fluid fasting time groups: less than 4 h (4.6%, 141 of 3,081), 4 to 8 h (6.0%, 219 of 3,652), 8 to 12 h (4.9%, 124 of 2,526), and more than 12 h (5.0%, 213 of 4,238). In epoch 2, the incidence of low systolic blood pressure was 6.9% (889 of 12,917) and varied across the fasting groups: less than 4 h (5.6%, 162 of 2,918), 4 to 8 h (8.1%, 285 of 3,531), 8 to 12 h (5.9%, 143 of 2,423), and more than 12 h (7.4%, 299 of 4,045); after adjusting for confounders, fasting 4 to 8 h (adjusted odds ratio, 1.33; 95% CI, 1.07 to 1.64; P = 0.009) and greater than 12 h (adjusted odds ratio, 1.28; 95% CI, 1.04 to 1.57; P = 0.018) were associated with significantly higher odds of low systolic blood pressure compared with the group who fasted less than 4 h, whereas the increased odds of low systolic blood pressure associated with fasting 8 to 12 h (adjusted odds ratio, 1.11; 95% CI, 0.87 to 1.42; P = 0.391) was nonsignificant.

Conclusions

Longer durations of clear fluid fasting in anesthetized children were associated with increased risk of postinduction low blood pressure during surgical preparation, although this association appeared nonlinear.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Ultrasonographic evaluation of gastric emptying after ingesting carbohydrate-rich drink in young children: A randomized crossover study

BACKGROUND

A recent consensus statement in Europe has suggested that the fasting time for clear liquid in children can be shortened to 1 hour before a surgery. However, the study to show that 1-hour fasting time for clear fluids is safe in young children is still lacking. This study aimed to investigate the gastric emptying time for carbohydrate-rich drink and regular 5% glucose solution in children aged 3-7 years.

METHODS

After overnight fasting, individuals were randomly assigned to ingest 5 mL kg^-1 of either carbohydrate-rich drink or 5% glucose solution. One week later, the same subjects were asked to ingest the other one. Ultrasonography was performed to examine the gastric contents. Gastric antral cross-sectional area was measured, and the gastric fluid volume was calculated before and after fluid ingestion within 120 minutes. The primary outcome was the gastric emptying time for both the clear fluids calculated using the antral cross-sectional area and logarithms of gastric fluid volume. The degrees of thirst and hunger of two drinks were evaluated using a visual analogue scale as the secondary outcomes.

RESULTS

Data from 16 individuals were analyzed. In the glucose solution group, the antral cross-sectional area and logarithms of gastric fluid volume returned to baseline at 30 minutes after ingestion. However, in the carbohydrate-rich drink group, the median [interquartile range; range] antral cross-sectional area (3.69 [2.64-5.15; 1.83-8.93] cm² vs 2.41 [2.10-2.96; 1.81-4.37] cm² , P < .001) and mean (95% confidence interval) logarithms of gastric fluid volume (2.54 [2.30-2.79] mL vs 2.12 [1.94-2.30] mL, P = .048) were still higher than at 60 minutes and returned to the baseline values at 90 minutes after ingestion, respectively. The degree of thirst was lower in the glucose solution group than that in the carbohydrate-rich drink group.

CONCLUSIONS

Gastric emptying of carbohydrate-rich drink is slower than that of 5% glucose solution but the residual gastric fluid volume is low one hour after ingestion of 5 mL kg^-1 of either fluid.

Ultrasound assessment of gastric emptying time in preterm infants: A prospective observational study

BACKGROUND

In paediatric anaesthesia, pre-operative fasting should be short to prevent discomfort, hunger, thirst and metabolic disorders. Current European guidelines recommend pre-operative fasting times of 4 h for breast milk and 6 h for formula milk in infants, whereas some national guidelines allow both until 4 h before anaesthesia.

OBJECTIVE

We evaluated the gastric emptying times of preterm infants after breast milk and formula milk, hypothesising that the mean gastric emptying time would be less than 4 h.

DESIGN

A prospective, observational, noninterventional cohort study.

SETTING

Neonatal ICU of a university hospital from August to September 2017.

PATIENTS

Twenty-two infants with a postmenstrual mean ± SD (range) age of 35 ± 2 (32 to 40) weeks were included. Based on their prescription plan, 10 infants received breast milk and 12 received formula milk with a total volume of 50 ± 16 (24 to 70) ml.

INTERVENTIONS

Gastric emptying was examined by sonographic measurements of the gastric antral area (GAA) before (FT0) and hourly after breast milk or formula milk feeding (FT1 to FT3).

MAIN OUTCOME MEASURES

Estimated gastric emptying time after enteral feeding with breast milk and formula milk in preterm infants.

RESULTS

The GAA of the preterm infants initially increased and subsequently decreased after feeding. GAA correlated significantly with fasting time (r = -0.53, P < 0.0001). At FT3 [199 ± 16 (175 to 225) min], GAA was 0.57 (0.42 to 0.91) cm and showed no difference compared with FT0. Using a linear regression model, the calculated mean gastric emptying time was 218 min.

CONCLUSION

The study shows that the mean gastric emptying time after enteral feeding with breast milk and formula milk is less than 4 h in preterm infants. These results support our current national fasting regimen of 4 h for any milk composition in infants before anaesthesia.

TRIAL REGISTRATION

German registry of clinical studies (DRKS-ID: DRKS 00013893).

Gastric content assessed with gastric ultrasound in paediatric patients prescribed a light breakfast prior to general anaesthesia: A prospective observational study

BACKGROUND

A light breakfast has been found to empty from the stomach within 4 hours in healthy volunteers.

AIM

The aim of this study was to investigate whether a light breakfast of yoghurt or gruel empties from the stomach within 4 hours, in children scheduled for general anaesthesia.

METHOD

In this observational cohort study, children aged 1-6 years scheduled for elective general anaesthesia were prescribed free intake of yoghurt or gruel 4 hours prior to induction. They were subsequently examined with gastric ultrasound within 4 hours of ingestion. In case of gastric contents, the gastric antral area was measured, and gastric content volume (GCV) was calculated.

RESULTS

Twenty children were included in the study and the ingested amount of gruel or yoghurt ranged 2.5-25 mL kg^-1 . In 15 cases, the stomach was empty with juxtaposed walls and no further measurements were made. In four cases, there was fluid present in the stomach, but the calculated gastric contents were <0.5 mL kg^-1 . One patient had solids in the stomach, and GCV in this patient was calculated to 2.1 mL kg^-1 . The patient with solids present had ingested 25 mL kg^-1 of gruel 4 hours prior to assessment. The planned procedure was therefore delayed 1 hour. There were no cases of pulmonary aspiration or vomiting.

CONCLUSION

A light breakfast 4 hours prior to induction may be considered, but there is need for further studies on safe limits for the volume ingested.