Effects of 2-, 4- and 12-hour fasting intervals on preoperative gastric fluid pH and volume, and plasma glucose and lipid homeostasis in children

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.

The Effects of Fasting Status on the Relative Risk of Pulmonary Aspiration in Acute Care Surgery Patients

BACKGROUND

Acute care surgery patients are often unfasted at the time of surgery, presenting a unique opportunity to study the effects of fasting on the risk of pulmonary aspiration. We aimed to determine the relative risk of aspiration in patients who were fasted at the time of surgery according to guidelines versus those in an unfasted state.

METHODS

A retrospective chart review of 100 patients who underwent appendectomy (n = 76) or exploratory laparotomy (n = 24) was conducted at a single institution in 2016-2017. Using the American Society of Anesthesiologists (ASA) Practice Guidelines for Preoperative Fasting, patients were stratified into study and control groups according to whether they were unfasted (nothing by mouth for <8 hours prior to surgery) or fasted (nothing by mouth for >8 hours prior to surgery). Data controlled for patients' age, sex, body mass index (BMI), most recent hemoglobin A1c, presence of gastroesophageal reflux disease (GERD), and presence of hiatal hernia.

RESULTS

Of the 76 patients who underwent appendectomy, 15% were unfasted with a total of 0 aspiration events (P < .001). Of the 24 patients who underwent exploratory laparotomy, 42% were unfasted with a total of 0 aspiration events (P < .001). This yields a relative risk of pulmonary aspiration of 1.0 (absolute risk of 0) in both the study and control groups.

DISCUSSION

In an acute care surgery population including patients who were not fasted according to guidelines, there was no increase in the risk of pulmonary aspiration.

LEVEL OF EVIDENCE

Epidemiological study; Level III.

Biopharmaceutical considerations in paediatrics with a view to the evaluation of orally administered drug products - a PEARRL review

OBJECTIVES

In this review, the current biopharmaceutical approaches for evaluation of oral formulation performance in paediatrics are discussed.

KEY FINDINGS

The paediatric gastrointestinal (GI) tract undergoes numerous morphological and physiological changes throughout its development and growth. Some physiological parameters are yet to be investigated, limiting the use of the existing in vitro biopharmaceutical tools to predict the in vivo performance of paediatric formulations. Meals and frequencies of their administration evolve during childhood and affect oral drug absorption. Furthermore, the establishment of a paediatric Biopharmaceutics Classification System (pBCS), based on the adult Biopharmaceutics Classification System (BCS), requires criteria adjustments. The usefulness of computational simulation and modeling for extrapolation of adult data to paediatrics has been confirmed as a tool for predicting drug formulation performance. Despite the great number of successful physiologically based pharmacokinetic models to simulate drug disposition, the simulation of drug absorption from the GI tract is a complicating issue in paediatric populations.

SUMMARY

The biopharmaceutics tools for investigation of oral drug absorption in paediatrics need further development, refinement and validation. A combination of in vitro and in silico methods could compensate for the uncertainties accompanying each method on its own.

Choosing Wisely in pediatric anesthesia: An interpretation from the German Scientific Working Group of Paediatric Anaesthesia (WAKKA)

Inspired by the Choosing Wisely initiative, a group of pediatric anesthesiologists representing the German Working Group on Paediatric Anaesthesia (WAKKA) coined and agreed upon 10 concise positive ("dos") or negative ("don'ts") evidence-based recommendations. (i) In infants and children with robust indications for surgical, interventional, or diagnostic procedures, anesthesia or sedation should not be avoided or delayed due to the potential neurotoxicity associated with the exposure to anesthetics. (ii) In children without relevant preexisting illnesses (ie, ASA status I/II) who are scheduled for elective minor or medium-risk surgical procedures, no routine blood tests should be performed. (iii) Parental presence during the induction of anesthesia should be an option for children whenever possible. (iv) Perioperative fasting should be safe and child-friendly with shorter real fasting times and more liberal postoperative drinking and enteral feeding. (v) Perioperative fluid therapy should be safe and effective with physiologically composed balanced electrolyte solutions to maintain a normal extracellular fluid volume; addition of 1%-2.5% glucose to avoid lipolysis, hypoglycemia, and hyperglycemia, and colloids as needed to maintain a normal blood volume. (vi) To achieve safe and successful airway management, the locally accepted airway algorithm and continued teaching and training of basic and alternative techniques of ventilation and endotracheal intubation are required. (vii) Ultrasound and imaging systems (eg, transillumination) should be available for achieving central venous access and challenging peripheral venous and arterial access. (viii) Perioperative disturbances of the patient's homeostasis, such as hypotension, hypocapnia, hypothermia, hypoglycemia, hyponatremia, and severe anemia, should not be ignored and should be prevented or treated immediately. (ix) Pediatric patients with an elevated perioperative risk, eg, preterm and term neonates, infants, and critically ill children, should be treated at institutions where all caregivers have sufficient expertise and continuous clinical exposure to such patients. (x) A strategy for preventing postoperative vomiting, emergence delirium, and acute pain should be a part of every anesthetic procedure.

Association of Preprocedural Fasting With Outcomes of Emergency Department Sedation in Children

IMPORTANCE

It is not clear whether adherence to preprocedural fasting guidelines prevent pulmonary aspiration and associated adverse outcomes during emergency department (ED) sedation of children.

OBJECTIVE

To examine the association between preprocedural fasting duration and the incidence of sedation-related adverse outcomes in a large sample of children.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a planned secondary analysis of a multicenter prospective cohort study of children aged 0 to 18 years who received procedural sedation for a painful procedure in 6 Canadian pediatric EDs from July 2010 to February 2015. The primary risk factor was preprocedural fasting duration. Secondary risk factors were age, sex, American Society of Anesthesiologists classification, preprocedural and sedation medications, and procedure type.

MAIN OUTCOMES AND MEASURES

Four outcomes were examined: (1) pulmonary aspiration, (2) the occurrence of any adverse event, (3) serious adverse events, and (4) vomiting.

RESULTS

A total of 6183 children with a median age of 8.0 years (interquartile range, 4.0-12.0 years), of whom 6166 (99.7%) had healthy or mild systemic disease (American Society of Anesthesiologists levels I or II), were included in the analysis. Of these, 2974 (48.1%) and 310 (5.0%) children did not meet American Society of Anesthesiologists fasting guidelines for solids and liquids, respectively. There were no cases of pulmonary aspiration. There were 717 adverse events (11.6%; 95% CI, 10.8%-12.4%), of which 68 (1.1%; 95% CI, 0.9%-1.3%) were serious adverse events and 315 (5.1%; 95% CI, 4.6%-5.7%) were vomiting. The odds ratio (OR) of occurrence of any adverse event, serious adverse events, and vomiting did not change significantly with each additional hour of fasting duration for both solids (any adverse event: OR, 1.00; 95% CI, 0.98 to 1.02; serious adverse events, OR, 1.01; 95% CI, 0.95-1.07; vomiting: OR, 1.00; 95% CI, 0.97-1.03) and liquids (any adverse event: OR, 1.00; 95% CI, 0.98-1.02; serious adverse events: 1.01, 95% CI, 0.95-1.07; vomiting: OR, 1.00; 95% CI, 0.96-1.03).

CONCLUSIONS AND RELEVANCE

In this study, there was no association between fasting duration and any type of adverse event. These findings do not support delaying sedation to meet established fasting guidelines.

Ultrasound assessment of gastric emptying after breakfast in healthy preschool children

BACKGROUND

In current guidelines, 6 hours of fasting is recommended for solids to limit the risk of pulmonary aspiration during anesthesia in children. Ultrasonography has recently been introduced to evaluate gastric volumes in children in the context of preanesthetic fasting. Therefore, in this study, we firstly evaluated the precision of ultrasound assessment of gastric volume in an experimental setting and secondly studied gastric emptying times after a normal breakfast in healthy preschool children using ultrasound.

METHODS

In a preliminary experiment, a pear-shaped elastic balloon was filled and emptied in 50 mL steps from 0 to 500 mL with water. After each step, the balloon antral area was measured using ultrasonography. Thereafter, gastric emptying was examined in healthy preschool children after normal breakfast by sonographic measurements of the gastric antral area in right lateral decubitus position at two consecutive timepoints. Correlation coefficients (Pearson, 95% CI) between the balloon antral area and the balloon volume or gastric antral area and fasting time were calculated and gastric emptying time was extrapolated by linear regression. Data are presented as mean (range).

RESULTS

In the balloon experiment, the balloon volume correlated significantly with the balloon antral area (63 measurements, r=.96, P<.0001, 95% CI 0.93 to 0.97). In the preschool child measurements, a total of 30 children (age 47 (36-66) months) were included. The gastric antral area correlated significantly with fasting time (r=-.69, P<.0001, 95% CI -0.8 to -0.51). The first gastric antral area after breakfast was significantly higher when compared to the second gastric antral area before lunch (10.4 ± 3.7 (1.7-17.8) vs 5.5 ± 2.6 (1.4-11.8) cm² ; mean difference -5.04, 95% CI -6.3 to -3.8, P<.0001). The calculated mean gastric emptying time was 236 minutes.

CONCLUSION

The results of the balloon experiment showed a high correlation between balloon antral area and balloon volume. In the preschool child measurements, gastric antral area correlated with fasting time, and the mean gastric emptying time was lower than 4 hours after breakfast. These results support a more liberal perioperative fasting regimen after a light meal or breakfast in routine pediatric anesthesia.

Ambulatory anesthetic care in children undergoing myringotomy and tube placement: current perspectives

PURPOSE

Myringotomy and tube placement is one of the most frequently performed ear, nose and throat (ENT) surgeries in the pediatric population. Effective anesthetic management is vital to ensuring successful ambulatory care and ensuring child and parental satisfaction.

RECENT FINDINGS

This review summarizes recently published studies about the long-term effects of general anesthesia in young children, novel approaches to preoperative fasting and simplified approaches to the assessment and management of emergence delirium (ED) and emergence agitation (EA). New developments in perioperative ambulatory care, including management of comorbidities and day care unit logistics, are discussed.

SUMMARY

Long-term follow-up of children exposed to general anesthesia before the age of 4 years has limited impact on academic achievement or cognitive performance and should not delay the treatment of common ENT pathology, which can impair speech and language development. A more liberal approach to fasting, employing a 6-4-0 regime allowing children fluids up until theater, may become an accepted practice in future. ED and EA should be discriminated from pain in recovery and, where the child is at risk of harm, should be treated promptly. Postoperative pain at home remains problematic in ambulatory surgery and better parental education is needed. Effective ambulatory care ultimately requires a well-coordinated team approach from effective preassessment to postoperative follow-up.

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

Supplemental Digital Content is available in the text.

Gastric Volume and Its Relationship to Underlying Pathology or Acid-suppressing Medication

Background

Pulmonary aspiration during sedation is a major concern for sedation providers, making identifying high-risk patients a priority. Gastric fluid volume (GFV), an accepted risk factor for aspiration, has not been well characterized in fasting children. We hypothesized that GFV would increase with gastrointestinal (GI) pathology and decrease with regular acid-suppressor use.

Aims

The primary objective was to determine baseline GFV in fasting children. The secondary objectives were to evaluate the effect of GI pathology and regular use of acid-suppressing medications on GFV.

Settings and Study Design

This was prospective, observational study.

Materials and Methods

We endoscopically aspirated and measured GFV of 212 children fasting for >6 h who were sedated for esophagogastroduodenoscopy (EGD). Inclusion criteria were children up to 21 years of age, with the American Society of Anesthesiologists physical Status I and II presenting for elective EGD. After determining baseline GFV, the effect of GI pathology and effect of regular acid-suppressing medication use on GFV was analyzed.

Statistical Analysis

Analysis of variance was used to compare the GFV among ages and pathology and medication groups. Student's t-test was used to compare GFV between genders and also to compare GFV in confounder analyses.

Results

For the studied 212 children, average GFV was 0.469 ± 0.448 mL/kg (0-2.663 mL/kg). We found no association between GI pathology and GFV (P = 0.147), or acid-suppressor use and GFV (P = 0.360).

Conclusions

Average GFV in this study falls within the range of prior EGD-measured GFV in fasting children. Contrary to our hypothesis, we found no association between pathologies or regular acid-suppressor use on GFV. On the basis of GFV, children with GI disorders or those using acid-suppressors do not appear to pose an increased risk of aspiration. Future studies should discern differences in effects on GFV of immediate preprocedural versus the regular use of acid-suppressing medications.

Perioperative intravenous fluid therapy in children: guidelines from the Association of the Scientific Medical Societies in Germany

This consensus- based S1 Guideline for perioperative infusion therapy in children is focused on safety and efficacy. The objective is to maintain or re-establish the child's normal physiological state (normovolemia, normal tissue perfusion, normal metabolic function, normal acid- base- electrolyte status). Therefore, the perioperative fasting times should be as short as possible to prevent patient discomfort, dehydration, and ketoacidosis. A physiologically composed balanced isotonic electrolyte solution (BS) with 1-2.5% glucose is recommended for the intraoperative background infusion to maintain normal glucose concentrations and to avoid hyponatremia, hyperchloremia, and lipolysis. Additional BS without glucose can be used in patients with circulatory instability until the desired effect is achieved. The additional use of colloids (albumin, gelatin, hydroxyethyl starch) is recommended to recover normovolemia and to avoid fluid overload when crystalloids alone are not sufficient and blood products are not indicated. Monitoring should be extended in cases with major surgery, and autotransfusion maneuvers should be performed to assess fluid responsiveness.

Low incidence of pulmonary aspiration in children allowed intake of clear fluids until called to the operating suite

BACKGROUND

International guidelines recommend 2 h of clear fluid fasting prior to general anesthesia. The pediatric anesthesia unit of Uppsala University Hospital has been implementing a more liberal fasting regime for more than a decade; thus, children scheduled for elective procedures are allowed to drink clear fluids until called to the operating suite.

AIM

To determine the incidence of perioperative pulmonary aspiration in pediatric patients allowed unlimited intake of clear fluids prior to general anesthesia.

METHOD

Elective pediatric procedures between January 2008 and December 2013 were examined retrospectively by reviewing anesthesia charts and discharge notes in the electronic medical record system. All notes from the care event and available chest x-rays were examined for cases showing vomiting, regurgitation, and/or aspiration. Pulmonary aspiration was defined as radiological findings consistent with aspiration and/or postoperative symptoms of respiratory distress after vomiting during anesthesia.

RESULTS

Of the 10,015 pediatric anesthetics included, aspiration occurred in three (0.03% or 3 in 10,000) cases. No case required cancellation of the surgical procedure, intensive care or ventilation support, and no deaths attributable to aspiration were found. Pulmonary aspiration was suspected, but not confirmed by radiology or continuing symptoms, in an additional 14 cases.

CONCLUSION

Shortened fasting times may improve the perioperative experience for parents and children with a low risk of aspiration.

Ontogeny of oral drug absorption processes in children

INTRODUCTION

A large proportion of prescribed drugs to children are administered orally. Age-related change in factors affecting oral absorption can have consequences for drug dosing.

AREAS COVERED

For each process affecting oral drug absorption, a systematic search has been performed using Medline to identify relevant articles (from inception till February 2012) in humans. This review presents the findings on age-related changes of the following processes affecting oral drug absorption: gastric pH, gastrointestinal motility, bile salts, pancreatic function, intestinal pH, intestinal drug-metabolizing enzymes and transporter proteins.

EXPERT OPINION

Clinicians should bear in mind the ontogeny of oral drug absorption processes when prescribing oral drugs to children. The authors' review shows large information gaps on almost all drug absorption processes. It is important that more knowledge is acquired on intestinal transit time, intestinal pH and the ontogeny of intestinal drug-metabolizing enzymes and drug transporter proteins. Furthermore, the ultimate goal in this field should be to predict more precisely the oral disposition of drugs in children across the entire pediatric age range.

Gum chewing during pre-anesthetic fasting

Many ad hoc fasting guidelines for pre-anesthetic patients prohibit gum chewing. We find no evidence that gum chewing during pre-anesthetic fasting increases the volume or acidity of gastric juice in a manner that increases risk, nor that the occasional associated unreported swallowing of gum risks subsequent aspiration. On the contrary, there is evidence that gum chewing promotes gastrointestinal motility and physiologic gastric emptying. Recommendations against pre-anesthetic gum chewing do not withstand scrutiny and miss an opportunity to enhance comfort and sense of wellbeing for patients awaiting anesthesia. Gum chewing during the pre-anesthetic nil per os (NPO) period would also permit the development of gum-delivered premedications and should be permitted in children old enough to chew gum safely. Gum chewing should cease when sedatives are given and all patients should be instructed to remove any chewing gum from the mouth immediately prior to anesthetic induction.

Preoperative fasting for preventing perioperative complications in children

BACKGROUND

Children, like adults, are required to fast before general anaesthesia with the aim of reducing the volume and acidity of their stomach contents. It is thought that fasting reduces the risk of regurgitation and aspiration of gastric contents during surgery. Recent developments have encouraged a shift from the standard 'nil-by-mouth-from-midnight' fasting policy to more relaxed regimens. Practice has been slow to change due to questions relating to the duration of a total fast, the type and amount of intake permitted.

OBJECTIVES

To systematically assess the effects of different fasting regimens (duration, type and volume of permitted intake) and the impact on perioperative complications and patient well being (aspiration, regurgitation, related morbidity, thirst, hunger, pain, comfort, behaviour, nausea and vomiting) in children.

SEARCH STRATEGY

We searched Cochrane Wounds Group Specialised Register (searched 25/6/09), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2 2009), Ovid MEDLINE (1950 to June Week 2 2009), Ovid EMBASE (1980 to 2009 Week 25), EBSCO CINAHL (1982 to June Week 3 2009), the National Research Register, relevant conference proceedings and article reference lists and contacted experts.

SELECTION CRITERIA

Randomised and quasi randomised controlled trials of preoperative fasting regimens for children were identified.

DATA COLLECTION AND ANALYSIS

Data extraction and trial quality assessment was conducted independently by three authors. Trial authors were contacted for additional information including adverse events.

MAIN RESULTS

This first update of the review identified two additional eligible studies, bringing the total number of included studies to 25 (forty seven randomised controlled comparisons involving 2543 children considered to be at normal risk of regurgitation or aspiration during anaesthesia). Only one incidence of aspiration and regurgitation was reported.Children permitted fluids up to 120 minutes preoperatively were not found to experience higher gastric volumes or lower gastric pH values than those who fasted. The children permitted fluids were less thirsty and hungry, better behaved and more comfortable than those who fasted.Clear fluids preoperatively did not result in a clinically important difference in children's gastric volume or pH. Evidence relating to the preoperative intake of milk was sparse. The volume of fluid permitted during the preoperative period did not appear to impact on children's intraoperative gastric volume or pH contents.

AUTHORS' CONCLUSIONS

There is no evidence that children who are denied oral fluids for more than six hours preoperatively benefit in terms of intraoperative gastric volume and pH compared with children permitted unlimited fluids up to two hours preoperatively. Children permitted fluids have a more comfortable preoperative experience in terms of thirst and hunger. This evidence applies only to children who are considered to be at normal risk of aspiration/regurgitation during anaesthesia.

Modern fasting guidelines in children

Pediatric fasting guidelines are intended to reduce the risk of pulmonary aspiration of gastric contents and facilitate the safe and efficient conduct of anesthesia. Recent changes in these guidelines, while assuring appropriate levels of patient safety, have been directed at improving the overall perioperative experience for infants, children, and their parents. Now after nearly 15 years of practice worldwide, the relative safety and benefits of allowing clear liquids up to 2 hr prior to anesthesia for otherwise healthy children are well established. Shortened fasting periods for breast milk (3 hr), formula (4 hr) and light meals (6 hr) are supported by accumulated experience and an evolving literature that includes evidence of minimal gastric fluid volumes (GFVs) at the time of surgery. Ideal fasting intervals for children with disorders that may affect gastrointestinal transit have yet to be determined.

Preoperative fasting for preventing perioperative complications in children

BACKGROUND

Children, like adults, are required to fast before general anaesthesia with the aim of reducing the volume and acidity of their stomach contents. It is thought that fasting reduces the risk of regurgitation and aspiration of gastric contents during surgery. Recent developments have encouraged a shift from the standard 'nil-by-mouth-from-midnight' fasting policy to more relaxed regimens. Practice has been slow to change due to questions relating to the duration of a total fast, the type and amount of intake permitted.

OBJECTIVES

To systematically assess the effects of different fasting regimens (duration, type and volume of permitted intake) and the impact on perioperative complications and patient wellbeing (aspiration, regurgitation, related morbidity, thirst, hunger, pain, comfort, behaviour, nausea and vomiting) in children.

SEARCH STRATEGY

We searched Cochrane Wounds Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, CINAHL, the National Research Register, relevant conference proceedings and article reference lists and contacted experts.

SELECTION CRITERIA

Randomised and quasi randomised controlled trials of preoperative fasting regimens for children were identified.

DATA COLLECTION AND ANALYSIS

Data extraction and trial quality assessment was conducted independently by two authors. Trial authors were contacted for additional information including adverse events.

MAIN RESULTS

Forty-three randomised controlled comparisons (from 23 trials) involving 2350 children considered to be at normal risk of regurgitation or aspiration during anaesthesia. Only one incidence of aspiration and regurgitation was reported. Children permitted fluids up to 120 minutes preoperatively were not found to experience higher gastric volumes or lower gastric pH values than those who fasted. The children permitted fluids were also less thirsty and hungry, better behaved and more comfortable than those who fasted. Clear fluids preoperatively did not result in a clinically important difference in the children's gastric volume or pH. Evidence relating to the preoperative intake of milk was sparse. The volume of fluid permitted during the preoperative period did not appear to impact on children's intraoperative gastric volume or pH contents.

AUTHORS' CONCLUSIONS

There is no evidence that children who are not permitted oral fluids for more than six hours preoperatively benefit in terms of intraoperative gastric volume and pH over children permitted unlimited fluids up to two hours preoperatively. Children permitted fluids have a more comfortable preoperative experience in terms of thirst and hunger. This evidence applies only to children who are considered to be at normal risk of aspiration/regurgitation during anaesthesia.

Gastroesophageal reflux and aspiration of gastric contents in anesthetic practice

General anesthesia may predispose patients to aspiration of gastroesophageal contents because of depression of protective reflexes during loss of consciousness. In addition, some patients may be at increased risk of pulmonary aspiration because of retention of gastric contents caused by pain, inadequate starvation, or gastrointestinal pathology resulting in reduced gastric emptying and gastroesophageal reflux. Despite increasing knowledge of the problems associated with aspiration, the relatively small incidence and associated mortality rates in the perioperative period do not appear to have changed markedly over the last few decades. In this review article, the physiological factors associated with an increased risk of gastroesophageal reflux and aspiration are considered together with some of the methods that are used to prevent aspiration. In particular, preoperative starvation, the use of drugs designed to increase gastric pH, recent developments in airway devices, and appropriate application of cricoid pressure are critically appraised.

Gastric contents in children presenting for upper endoscopy

Previous studies of gastric contents in children presenting for surgery specifically excluded those with gastrointestinal disorders. Because these children often need sedation or anesthesia for procedures such as upper endoscopy, it is important to determine the gastric fluid volume and pH in this group to better characterize their risk of aspiration. We therefore analyzed the gastric fluid volume and pH of children with a variety of gastrointestinal symptoms presenting for upper endoscopy. After obtaining institutional review board approval, the stomach contents of 248 children (aged 2 mo to 18 yr) presenting for upper endoscopy were prospectively measured under direct endoscopic vision. Children were fasted for both solids and liquids for at least 6 h (<6 mo) or 8 h (>6 mo). Gastric fluid pH was measured using pH paper. Children received either deep sedation or general anesthesia and were grouped according to their presenting diagnosis. Results were analyzed by using analysis of variance, Kruskal-Wallis, and correlation (P value < 0.05). The mean gastric fluid volume was 0.35 +/- 0.45 mL/kg (range 0-3.14 mL/kg), and the mean gastric fluid pH was 1.37 +/- 1.6 (range 1-7). Of the children, 33% had gastric fluid volumes >0.4 mL/kg, 87% had gastric fluid pH <2.5, and 30% had gastric fluid volume >0.4 mL/kg and pH <2.5. Children with the presenting complaint of abdominal pain had the largest gastric fluid volumes. These data are not appreciably different from historical controls (healthy children fasted for an equivalent period of time who did not have gastrointestinal symptoms).

IMPLICATIONS

When fasted for at least 6-8 h, children with a history of gastrointestinal symptoms presenting for upper endoscopy did not have gastric contents with increased volume and acidity compared with previously published groups of children without gastric symptoms who were fasted the same length of time. These results do not support the argument that children with gastrointestinal symptoms pose an increased anesthetic risk for aspiration.

Pre-operative fasting for paediatric anaesthesia. A survey of current practice

There has recently been much debate about pre-operative fasting for paediatric anaesthesia. There is no consensus about the optimum fasting times for children undergoing elective surgery. In order to establish a standard for paediatric pre-operative fasting times, we undertook a postal survey, targeting members of the Association of Paediatric Anaesthetists resident in the United Kingdom and Ireland in 1995. One hundred and sixty-three questionnaires were dispatched, 131 (80%) were returned and 110 (67%) were complete. The results show that the following guidelines for duration of fast are acceptable to the majority of respondents-neonates: 2 h for clear fluids, 4 h for breast and formula milk; infants: 2 h for clear fluids, 4 h for breast milk, 6 h for formula milk and solids; children: 2 h for clear fluids, 6 h for milk and solids. We suggest that these times be used as guidelines and audited for pre-operative fasting in paediatric anaesthesia.

Sedation in children: adequacy of two-hour fasting

OBJECTIVES

(1) To investigate the relationship between the duration of time that children fasted before a procedure and their gastric volume and pH at the time of the procedure. (2) To compare the variables of gastric pH and volume with historical standards.

METHODS

We performed 285 gastroscopies for children aged 0.1 to 18.6 years (mean, 7.5 +/- 5.3) between October 1991 and January 1995. Duration of fasting was 0.5 to 24 hours (mean, 6.7 +/- 5.3) after ingestion of clear liquids. Immediately after intravenously administered sedation, the gastric contents were removed endoscopically with suction and direct visualization to ensure complete evacuation. The volume and pH of the gastric contents were measured and analyzed in comparison with the duration of fasting. The values obtained were also compared with historical standards thought to minimize the risk of aspiration pneumonia: gastric volume 0.4 ml or less per kilogram of body weight and pH of 2.5 or greater.

RESULTS

There was no significant correlation between duration of fasting and either gastric volume divided by body weight (mean, 0.68 +/- 1.31 ml/kg; range, 0 to 15.23 ml/kg) or pH (mean, 2.03 +/- 1.40; range, 1 to 8). There was less no significant difference in the percentage of children with gastric volume of 0.4 ml/kg or less or with pH of 2.5 or greater between the groups with the following fasting times: 30 minutes to 3 hours, more than 3 hours to 8 hours, and more than 8 hours.

CONCLUSIONS

On the basis of the data in this study and a review of the literature, we concluded that (1) fasting longer than 2 hours after ingesting clear liquids does not significantly change gastric volume or pH, (2) there is no advantage in requiring children to fast for longer than 2 hours after clear liquid ingestion before sedation or anesthesia for any procedure, and (3) fewer than half of pediatric patients actually achieve the "desirable" values of a gastric volume of 0.4 ml/kg or less and a pH value of 2.5 pH units or more, regardless of fast duration, even though these values are presented in the literature as a goal to minimize the risk of aspiration pneumonia.