When fasted is not empty: a retrospective cohort study of gastric content in fasted surgical patients†

Ultrasound evaluation of gastric residual volume in fasting end-stage renal failure patients

STUDY OBJECTIVE

To evaluate the gastric contents and gastric residual volume in patient with end-stage renal failure by gastric ultrasound.

DESIGN

Prospective observational study.

SETTING

Tertiary care teaching hospital.

PATIENTS

Adults of either gender with BMI < 40 kg/m2 with end-stage renal failure scheduled to undergo arteriovenous graft or fistula.

INTERVENTIONS & MEASUREMENTS

The cross-sectional area of the gastric antrum was measured by gastric ultrasound with patient in both supine and right lateral decubitus positions. The volume of the gastric contents were calculated using suitable validated formula. In addition, the nature of the gastric contents was also determined by gastric ultrasound.

MAIN RESULTS

The incidence of delayed gastric emptying was found to be 57.7% in the population studied despite following the prescribed preoperative standard fasting guidelines.

CONCLUSIONS

There is a high incidence of delayed gastric emptying in patients with end-stage renal failure presenting for surgery which may predispose them to risk of pulmonary aspiration perioperatively.

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.

Glucagon-Like Peptide-1 Receptor Agonist Use and Residual Gastric Content Before Anesthesia

Importance

Glucagon-like peptide-1 receptor agonist (GLP-1 RA) use is rapidly increasing in the US, driven by its expanded approval for weight management in addition to hyperglycemia management in patients with type 2 diabetes. The perioperative safety of these medications, particularly with aspiration risk under anesthesia, is uncertain.

Objective

To assess the association between GLP-1 RA use and prevalence of increased residual gastric content (RGC), a major risk factor for aspiration under anesthesia, using gastric ultrasonography.

Design, Setting, and Participants

This cross-sectional study prospectively enrolled patients from a large, tertiary, university-affiliated hospital from June 6 through July 12, 2023. Participants followed preprocedural fasting guidelines before an elective procedure under anesthesia. Patients with altered gastric anatomy (eg, from previous gastric surgery), pregnancy, recent trauma (<1 month), or an inability to lie in the right lateral decubitus position for gastric ultrasonography were excluded.

Exposure

Use of a once-weekly GLP-1 RA.

Main Outcomes and Measures

The primary outcome was the presence of increased RGC, defined by the presence of solids, thick liquids, or more than 1.5 mL/kg of clear liquids on gastric ultrasonography. Analysis was adjusted for confounders using augmented inverse probability of treatment weighting, a propensity score-based technique. Secondarily, the association between the duration of drug interruption and the prevalence of increased RGC was explored.

Results

Among the 124 participants (median age, 56 years [IQR, 46-65 years]; 75 [60%] female), the prevalence of increased RGC was 56% (35 of 62) in patients with GLP-1 RA use (exposure group) compared with 19% (12 of 62) in patients who were not taking a GLP-1 RA drug (control group). After adjustment for confounding, GLP-1 RA use was associated with a 30.5% (95% CI, 9.9%-51.2%) higher prevalence of increased RGC (adjusted prevalence ratio, 2.48; 95% CI, 1.23-4.97). There was no association between the duration of GLP-1 RA interruption and the prevalence of increased RGC (adjusted odds ratio, 0.86; 95% CI, 0.65-1.14).

Conclusions and Relevance

Use of a GLP-1 RA was independently associated with increased RGC on preprocedural gastric ultrasonography. The findings suggest that the preprocedural fasting duration suggested by current guidelines may be inadequate in this group of patients at increased risk of aspiration under anesthesia.

Preoperative ultrasound assessment of gastric content in patients with diabetes: A meta-analysis based on a systematic review of the current literature

STUDY OBJECTIVE

To conduct a systematic literature review of the current evidence on the effect of diabetes mellitus on gastric volume observed during a preoperative ultrasound examination. Using the results of this systematic literature review, a meta-analysis was performed to investigate whether there was an association between diabetes mellitus and an increased risk of presenting with a high-risk stomach (gastric volume associated with an increased risk of pulmonary aspiration).

DESIGN

Review article and meta-analysis.

SETTING

Review of published literature.

PATIENTS

A total of 3366 patients underwent surgery.

INTERVENTION

Gastric ultrasound examination.

MEASUREMENTS

Data for the meta-analysis and literature review were collected from the PubMed/Medline, Embase, Web of Science, and Google Scholar databases of the National Library of Medicine from the date of inception to January 2023. All included studies measured the gastric antral cross-sectional area and/or gastric residual volume in patients with diabetes and those without diabetes. The data utilized in the meta-analysis included all studies that evaluated the incidence of high-risk stomachs based on ultrasonographic measurements of the gastric antral cross-sectional area or gastric residual volume.

MAIN RESULTS

Most collated studies revealed that diabetes mellitus was associated with increased antral cross-sectional area and gastric residual volume. A meta-analysis of published reports indicated that patients with diabetes have an increased rate of high-risk stomachs.

CONCLUSIONS

Diabetes mellitus is associated with an increased rate of high-risk stomachs. The authors recommend large prospective trials to ascertain the safety of the current fasting guidelines for patients with diabetes undergoing surgery.

Gastric Volume and Antral Area in the Fasting State: A Meta-analysis of Individual Patient Data

BACKGROUND

Pulmonary aspiration of gastric content is a serious anesthetic complication. Gastric point-of-care ultrasound can determine the type and volume of gastric content when clinical information is equivocal. However, a cutoff value of either antral cross-sectional area or volume that may be considered as the upper limit of normal in fasting subjects is still controversial. The aim of this study is to characterize the distribution of baseline antral area and volume in fasting adult subjects and to identify an upper limit (95th percentile) of these distributions.

METHODS

The authors conducted a meta-analysis of individual participant data of primary studies from an academic research network of investigators collaborating in gastric ultrasound. Studies between January 2009 and December 2020 were included.

RESULTS

Twelve primary studies met inclusion criteria and were included in the analysis with a sample size of 1,203 subjects. The 95th percentile of area values (measured in the right lateral decubitus) was 9.9 cm2 (95% CI, 9.4 to 10.4), and of volume, 2.3 ml/kg (95% CI, 2.3 to 2.4). In addition, an antrum grade 0 or 1 indicates a 98% probability of an antral area below the 95th percentile.

CONCLUSIONS

An area of 10 cm2 measured in the right lateral decubitus could be a simple, data-driven upper limit of antral area that could serve as a surrogate of upper limit of normal gastric volume values in fasting adults. These results are limited by the highly selected sampling of the studies included.

EDITOR’S PERSPECTIVE

Gastric point-of-care ultrasonography in patients undergoing radical gastrointestinal surgery before anesthetic induction: an observational cohort study

BACKGROUND

Pulmonary aspiration of gastric contents is a serious perioperative complication. Patients with gastric cancer may experience delayed gastric emptying. However, the role of qualitative and quantitative gastric ultrasound assessments in this patient population before anesthesia induction has not yet been determined.

METHODS

Adult patients with gastrointestinal cancer were recruited and examined using gastric point-of-care ultrasound (POCUS) before anesthetic induction from March 2023 to August 2023 in a tertiary cancer center. Three hundred patients with gastric cancer were conducted with POCUS prior to induction, and three hundred patients with colorectal cancer were included as controls. The cross-sectional area (CSA) of the gastric antrum and gastric volumes (GV) were measured and calculated. We determined the nature of the gastric contents and classified the antrum using a 3-point grading system. A ratio of GV to body weight > 1.5mL/Kg was defined as a high risk of aspiration.

RESULTS

In patients with gastric cancer, 70 patients were classified as grade 2 (23%, including 6 patients with solid gastric contents) and 63 patients (21%) were identified as having a high risk of aspiration. Whereas in patients with colorectal cancer, only 11 patients were classified as grade 2 (3.7%), and 27 patients (9.7%) were identified as having a high risk of aspiration. A larger tumor size (OR:1.169, 95% CI 1.045-1.307, P = 0.006), tumor located in antrum (OR:2.304, 95% CI 1.169-4.539,P = 0.016), gastrointestinal obstruction (OR:21.633, 95% CI 4.199-111.443, P < 0.0001) and more lymph node metastasis (OR:2.261, 95% CI 1.062-4.812, P = 0.034) were found to be positively while tumor site at cardia (OR:0.096, 95% CI 0.019-0.464, P = 0.004) was negatively associated with high aspiration risk in patients with gastric cancer.

CONCLUSION

The Gastric POCUS prior to induction provides an assessment of the status of gastric emptying and can identify the patients at high risk of aspiration, especially those with gastric cancer.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ( www.chictr.org.cn ) identifier: ChiCTR2300069242; registered 10 March 2023.

Development and validation of a novel nomogram model to assess the risk of gastric contents in outpatients undergoing elective sedative gastrointestinal endoscopy procedures

BACKGROUND

Gastric contents may contribute to patients' aspiration during anesthesia. Ultrasound can accurately assess the risk of gastric contents in patients undergoing sedative gastrointestinal endoscopy (GIE) procedures, but its efficiency is limited. Therefore, developing an accurate and efficient model to predict gastric contents in outpatients undergoing elective sedative GIE procedures is greatly desirable.

METHODS

This study retrospectively analyzed 1501 patients undergoing sedative GIE procedures. Gastric contents were observed under direct gastroscopic vision and suctioned through the endoscope. High-risk gastric contents were defined as having solid content or liquid volume > 25 ml and pH < 2.5; otherwise, they were considered low-risk gastric contents. Univariate analysis and multivariate analysis were used to select the independent risk factors to predict high-risk gastric contents. Based on the selected independent risk factors, we assigned values to each independent risk factor and established a novel nomogram. The performance of the nomogram was verified in the testing cohort by the metrics of discrimination, calibration, and clinical usefulness. In addition, an online accessible web calculator was constructed.

RESULTS

We found BMI, cerebral infarction, cirrhosis, male, age, diabetes, and gastroesophageal reflux disease were risk factors for gastric contents. The AUROCs were 0.911 and 0.864 in the development and testing cohort, respectively. Moreover, the nomogram showed good calibration ability. Decision curve analysis and Clinical impact curve demonstrated that the predictive nomogram was clinically useful. The website of the nomogram was https://medication.shinyapps.io/dynnomapp/.

CONCLUSIONS

This study demonstrates that clinical variables can be combined with algorithmic techniques to predict gastric contents in outpatients. Nomogram was constructed from routine variables, and the web calculator had excellent clinical applicability to assess the risk of gastric contents accurately and efficiently in outpatients, assist anesthesiologists in assessment and identify the most appropriate patients for ultrasound.

Evaluation of the 'Sip Til Send' regimen before elective caesarean delivery using bedside gastric ultrasound: A paired cohort pragmatic study

BACKGROUND

Pre-operative fasting is routinely advocated to avoid pulmonary aspiration. The European Society of Anaesthesiology and Intensive Care (ESAIC) recommends a fasting period of 2 h for liquids before surgery. Liberal drinking policies such as the 'Sip Til Send' are a suggested alternative to maintain hydration before surgery.

OBJECTIVES

To compare residual gastric volumes in fully fasted nonlabouring parturients before elective caesarean delivery with the 'Sip Til Send' with water liberal drinking protocol. Our hypothesis was the 'Sip Til Send' would be noninferior to standard fasting at minimising the residual gastric volume immediately before surgery.

DESIGN

A paired cohort prospective observational pragmatic study using gastric ultrasound, analysed by an operator blinded to the fasting status of each scan.

SETTING

A tertiary maternity hospital in Dublin, Ireland. The study was conducted between January and June 2023.

PARTICIPANTS

Pregnant women about to undergo elective caesarean delivery who had followed ESAIC fasting guidelines before admission.

INTERVENTIONS

Each participant underwent two pairs (semi-recumbent and the semi-recumbent right lateral positions) of standardised ultrasound examinations of the gastric antrum: the order of these scans was randomised. The first pair of scans occurred on admission before the 'Sip Til Send' protocol commenced, the other pair just before spinal anaesthesia for caesarean delivery, after a variable time following the 'Sip Til Send' protocol.

MAIN OUTCOME MEASURE

The primary outcome was the difference in antral cross-sectional area (CSA) between the fully fasted women on admission and the same women after following the 'Sip Til Send' protocol until just before spinal anaesthesia.

RESULTS

Fifty-eight women were randomised for the study: 55 and 54 scans in the semi-recumbent position on admission, and 55 and 54 scans in the right lateral position just before spinal anaesthesia. The mean differences (95% CI) in CSA in the semi-recumbent and RL positions were 0.07 (-0.39 to 0.53) cm 2 and 0.04 (-0.60 to 0.68) cm 2 , respectively. Since the of 95% CIs did not cross the predefined noninferiority margin of 0.88 cm 2 , 'Sip Til Send' was noninferior to fully fasting in in terms of the antral CSA.

CONCLUSION

The 'Sip Til Send' protocol of liberal hydration with water was noninferior to standard fasting prior to elective caesarean delivery.

TRIAL REGISTRY NUMBER

NCT05783427 ClinicalTrials.gov.

Feasibility and Utility of Routine Point-of-Care Gastric Ultrasonography in Patients Undergoing Upper Gastrointestinal Endoscopy Procedures: A Prospective Cohort Study

OBJECTIVES

Previous studies have indicated that point-of-care ultrasonography (POCUS) of the gastric antrum can predict the adequacy of fasting before surgery and anesthesia. The aim of this study was to evaluate the utility of gastric POCUS in patients undergoing upper gastrointestinal (GI) endoscopy procedures.

METHODS

We performed a single-center cohort study in patients undergoing upper GI endoscopy. Consenting patient's gastric antrum was scanned before anesthetic care for endoscopy to determine the cross-sectional area (CSA) and qualitatively determine safe and unsafe contents. Further, an estimate of residual gastric volume was determined using the formula and the nomogram methods. Subsequently, gastric secretions aspirated during endoscopy were quantified and further correlated with nomogram and formula-based assessments. No patient required a change in the primary anesthetic plan except for using rapid sequence induction in those with unsafe contents on POCUS scans.

RESULTS

Qualitative ultrasound measurements consistently determined safe and unsafe gastric residual contents in 83 patients enrolled in the study. Unsafe contents were determined by qualitative scans in 4 out of 83 cases (5%) despite adequate fasting status. Quantitatively, only a moderate correlation was demonstrated between measured gastric volumes and nomogram (r = .40, 95% CI: 0.20, 0.57; P = .0002) or formula-based (r = .38, 95% CI: 0.17, 0.55; P = .0004) determinations of residual gastric volumes.

CONCLUSION

In daily clinical practice, qualitative POCUS determination of residual gastric content is a feasible and useful technique to identify patients at risk of aspiration before upper GI endoscopy procedures.

Pre-operative gastric ultrasound in patients at risk of pulmonary aspiration: a prospective observational cohort study

Point-of-care gastric sonography offers an objective approach to assessing individual pulmonary aspiration risk before induction of general anaesthesia. We aimed to evaluate the potential impact of routine pre-operative gastric ultrasound on peri-operative management in a cohort of adult patients undergoing elective or emergency surgery at a single centre. According to pre-operative gastric ultrasound results, patients were classified as low risk (empty, gastric fluid volume ≤ 1.5 ml.kg-1 body weight) or high risk (solid, mixed or gastric fluid volume > 1.5 ml.kg-1 body weight) of aspiration. After sonography, examiners were asked to indicate changes in aspiration risk management (none; more conservative; more liberal) to their pre-defined anaesthetic plan and to adapt it if patient safety was at risk. We included 2003 patients, 1246 (62%) of which underwent elective and 757 (38%) emergency surgery. Among patients who underwent elective surgery, 1046/1246 (84%) had a low-risk and 178/1246 (14%) a high-risk stomach, with this being 587/757 (78%) vs. 158/757 (21%) among patients undergoing emergency surgery, respectively. Routine pre-operative gastric sonography enabled changes in anaesthetic management in 379/2003 (19%) of patients, with these being a more liberal approach in 303/2003 (15%). In patients undergoing elective surgery, pre-operative gastric sonography would have allowed a more liberal approach in 170/1246 (14%) and made a more conservative approach indicated in 52/1246 (4%), whereas in patients undergoing emergency surgery, 133/757 (18%) would have been managed more liberally and 24/757 (3%) more conservatively. We showed that pre-operative gastric ultrasound helps to identify high- and low-risk situations in patients at risk of aspiration and adds useful information to peri-operative management. Our data suggest that routine use of pre-operative gastric ultrasound may improve individualised care and potentially impact patient safety.

Point of care gastric ultrasound to predict aspiration in patients undergoing urgent endotracheal intubation in the emergency medicine department

BACKGROUND

One significant cause of morbidity and mortality in patients undergoing endotracheal intubation is the aspiration of gastric contents. Its prevalence is more in the emergency than in elective settings. Point-of-care gastric ultrasound (GUS) is a non-invasive bedside ultrasonogram that provides both qualitative and quantitative information about the stomach contents. The diagnostic accuracy of GUS in terms of gastric parameters (measured antral diameters, antral cross-sectional area, and calculated gastric volume) to predict aspiration is yet unknown. We aim to determine this in the patients undergoing urgent emergency intubation (UEI) in the emergency department.

METHODOLOGY

A prospective observational study was conducted at the emergency department of a tertiary healthcare center in India. Patients requiring UEI were identified and a bedside gastric ultrasound was done in the right lateral decubitus position using low frequency curved array probe. The qualitative data and the antral diameters (anteroposterior and craniocaudal) were assessed. The patient's clinical parameters and history regarding the last meal were noted. The cross-sectional area of gastric antrum was calculated using CSA = (AP × CC) π/4. The gastric volume is estimated using Perla's formula: GV = 27.0 + 14.6(RLD CSA) -1.28(age).

RESULTS

A hundred patients requiring urgent endotracheal intubation were enrolled in the study. Visible aspiration was more in participants with a distended gastric status (χ2 = 16.880, p =  < 0.001). The median gastric volume in the patients who aspirated was 146.37 mL, and it ranged from 111.59 mL-201.01 mL. Using ROC analysis, a cut-off of CC diameter ≥ 2.35 cm (sensitivity 88%, specificity 91%) and AP diameter ≥ 5.15 cm (sensitivity 88%, specificity 87%) predicts aspiration. A calculated USG CSA cut-off ≥ 9.27cm2 (sensitivity 100%, specificity 87%) and an USG gastric volume ≥ 111.594 mL (sensitivity 100%, a specificity 92%) predicts aspiration.

CONCLUSION

Point-of-care gastric ultrasound is an useful non-invasive bedside tool for risk stratification for aspiration in busy emergency rooms. We present threshold gastric antral parameters that can be used to predict aspiration along with its diagnostic accuracy. This can help the treating ED physician take adequate precautions, decide on intubation techniques and treatment modifications to aid in better patient management.

Ultrasound assessment of gastric content in patients undergoing laparoscopic cholecystectomy after preoperative oral carbohydrates: a prospective, randomized controlled, double-blind study

Background

To evaluate the gastric volume and nature after drinking preoperative oral carbohydrates in patients undergoing laparoscopic cholecystectomy via ultrasonography.

Methods

One hundred patients who had been scheduled for elective laparoscopic cholecystectomy were enrolled and randomized into the traditional fasting group (Control group, n = 50) and the carbohydrate group (CHO group, n = 50). Patients in the Control group fasted solids and drink from midnight, the day before surgery. Patients in the CHO group drank 800 ml and 400 ml of oral carbohydrates 11 and 3 h before surgery, respectively. At 2 h after oral carbohydrates (T1), all patients underwent an ultrasound examination of residual gastric contents; if the patients had a full stomach, the assessment was performed again 1 h later (T2). A stomach containing solid contents or >1.5 ml/kg of liquid was considered "full". The primary outcome was full stomach incidences at the above time points. The secondary outcomes included gastric antral CSA in the right lateral decubitus (RLD) and semi-sitting positions, as well as gastric volume (GV), GV per weight (GV/kg), and Perla's grade at T1.

Results

Compared with the Control group, the incidence of entire stomach was significantly high in the CHO group 2 h after oral carbohydrates. At the T1 time point, 6 patients (13.3%) in the Control group and 14 patients (30.4%) in the CHO group presented with a full stomach [95% confidence interval (CI), (0.96-5.41), P = 0.049]. At T2, 3 patients (6.7%) in the Control group and 4 patients (8.7%) in the CHO group had a full stomach, with no marked differences between the two groups [95% CI, (0.31-5.50), P = 0.716]. Compared with the Control group, CSA in the semi-sitting and RLD positions, GV and GV/W were significantly high in the CHO group at T1 (P < 0.05). The median (interquartile range) of the Perlas grade was 1 (0-1) in the Control group and 1(1-1.25) in the CHO group (P = 0.004).

Conclusion

Cholecystectomy patients experience a 2 h delay in gastric emptying after receiving preoperative carbohydrates. In LC patients, the fasting window for oral carbohydrates before surgery should be adequately prolonged.

Clinical Trail registration

Chinese Clinical Trail Registry, No: ChiCTR2200055245.

Ultrasonographic Assessment of Gastric Volume in Fasted Patients Undergoing Gastrointestinal Endoscopy Under Sedation

Purpose

In this prospective observational study, an ultrasonographic measurement of antral cross-sectional area (ACSA) was conducted to evaluate the gastric content and volume as well as to identify high-risk stomach in non-pregnant adult surgical patients adhering to preanesthetic fasting guidelines.

Patients and Methods

Fasted patients undergoing gastrointestinal endoscopy under sedation were included. Ultrasonographic measurements of ACSA were conducted in both semi-recumbent and right lateral decubitus positions before endoscopic procedures. Gastroscopy was employed to guide the measurement of suctioned gastric volume (GV). Ultrasonography was performed to assess gastric contents and identify patients with high-risk stomach. The relationship between ACSA and suctioned GV was also evaluated.

Results

ACSA was evaluated in 736 out of 782 patients. A significant positive correlation was discovered between ACSA in the right lateral decubitus position and suctioned GV, which was more reliable than in the semi-recumbent position. To analyze high-risk stomach with a GV > 100 mL, the cutoff value of ACSA in the right lateral decubitus was found to be 7.5 cm2, with the AUC, sensitivity and specificity of 0.80 (95% CI, 0.76-0.82; P<0.001), 82.4% and 67.3%, respectively. A novel mathematical model based on ACSA to estimate GV in non-pregnant fasted adults was presented.

Conclusion

Ultrasonographic measurement of ACSA can assist anesthesiologists in estimating the risk of pulmonary aspiration of gastric contents during general anesthesia and sedation.

Influence of semaglutide use on the presence of residual gastric solids on gastric ultrasound: a prospective observational study in volunteers without obesity recently started on semaglutide

PURPOSE

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) have become increasingly popular as both diabetic and weight loss therapies. One effect of this class of medication is delayed gastric emptying, which may impact the risk of aspiration during anesthesia delivery.

METHODS

In this prospective study, we used gastric ultrasound to evaluate the presence of solid gastric contents in both supine and lateral positions after an eight-hour fast in those taking GLP-1RA compared with controls. Participants underwent a second ultrasound evaluation two hours later after drinking 12 fluid ounces of water (approximately 350 mL).

RESULTS

Twenty adults voluntarily enrolled, giving a total of ten participants in each group. In the supine position, 70% of semaglutide participants and 10% of control participants had solids present on gastric ultrasound (risk ratio [RR], 3.50; 95% confidence interval [CI], 1.26 to 9.65; P = 0.02.) In the lateral position, 90% of semaglutide participants and 20% of control participants had solids identified on gastric ultrasound (RR, 7.36; 95% CI, 1.13 to 47.7; P = 0.005). Two hours after drinking clear liquids, the two groups did not differ in the lateral position, but in the supine position, 90% of control group participants were rated as empty compared with only 30% of semaglutide group participants (P = 0.02).

CONCLUSIONS

This study provides preliminary evidence that GLP-1RAs may affect gastric emptying and residual gastric contents following an overnight fast and two hours after clear liquids, which may have implications for aspiration risk during anesthetic care.

The correlation between patient satiety sensation and total gastric fluid volume: a prospective observational study

PURPOSE

Surgical patients are asked to adhere to preoperative fasting guidelines to minimize gastric contents. Large fluid volumes or solid content can still be present as shown with gastric ultrasound. It has been suggested that additional rating of patients' satiety, measured as the feeling of hunger and thirst, could help clinicians to better judge emptying of the stomach.

METHODS

We performed a prospective observational study in fasted elective surgical patients. The primary objective was to investigate the correlation between hunger measured on a 0-10 numeric rating scale and total gastric fluid volume measured with gastric ultrasonography. Secondary objectives included the correlation between 1) thirst and total gastric fluid volume and 2) hunger, thirst, and the Perlas grading scale score.

RESULTS

We included 515 patients. The exam was inconclusive in 14 individuals (2.7%). The Spearman correlation coefficient between gastric fluid volumes and hunger was 0.11 (95% confidence interval [CI], 0.02 to 0.20) (P = 0.01). The correlation between gastric fluid volumes and thirst was 0.11 (95% CI, 0.02 to 0.20) (P = 0.02). Between antral grades and numeric rating scale, the correlation coefficient was 0.00 (95% CI, -0.09 to 0.09) (P = 1.00) for thirst and 0.00 (95% CI, -0.08 to 0.09) (P = 0.94) for hunger. Ten patients (2.0%) had solid content, 24 presented a grade 2 antrum (4.8%).

CONCLUSION

This study suggests that the correlation between total gastric fluid volume and satiety sensation is very weak. Satiety did not reliably predict total gastric fluid volume.

STUDY REGISTRATION

ClinicalTrials.gov (NCT04884373); registered 13 May 2021.

Carbohydrate Loading and Aspiration Risk in Bariatric Patients: Safety in Preoperative Enhanced Recovery Protocols

BACKGROUND

Enhanced recovery protocols have been developed to improve perioperative outcomes; however, there is ongoing concern for aspiration with recent oral intake in patients with obesity, who may be predisposed to impaired gastrointestinal motility and greater gastric volumes. We aim to study the safety of a 300-mL preoperative carbohydrate-loading drink preceding bariatric surgery.

STUDY DESIGN

Data were collected prospectively from patients undergoing primary bariatric surgery. All bariatric patients at our institution are prescribed a proton pump inhibitor for 4 weeks before surgery and undergo a screening preoperative esophagogastroduodenoscopy (EGD) before surgery with a traditional 8-hour fast (NOCARB), followed by an intraoperative day-of-operation EGD with carbohydrate loading (CARB) 2 to 4 hours before incision. Gastric volumes and pH are measured after being endoscopically suctioned via direct visualization during both settings.

RESULTS

We identified 203 patients: 94 patients (46.3%) in the CARB group and 109 patients (53.7%) in the NOCARB group. The patients were 82.3% female with a mean age of 42.8 years and average BMI of 41.7 kg/m 2 . There was no difference in gastric volume between NOCARB and CARB (17.0 vs 16.1 mL, p = 0.59). The NOCARB group had lower pH values than the CARB group (2.8 vs 3.8, p = 0.001). Subset analysis of 23 patients who had measurements on both screening and intraoperative EGD revealed lower gastric volumes in CARB patients (13.3 vs 18.3, p < 0.0001).

CONCLUSIONS

When included in an enhanced recovery protocol, proton pump inhibitor use and preoperative carbohydrate loading 2 to 4 hours before bariatric surgery does not increase aspiration risk based on gastric volumes and pH and should be strongly considered in all eligible bariatric patients.

Ultrasonic evaluation of metoclopramide's effect on gastric motility in emergency trauma patients

Objective: The present study aimed to use bedside ultrasound to evaluate the effects of metoclopramide on gastric motility in patients being treated for trauma in the emergency department. Methods: Fifty patients underwent an ultrasound immediately after attending the emergency department of Zhang Zhou Hospital due to trauma. The patients were randomly divided into two groups: a metoclopramide group (group M, n = 25) and a normal saline group (group S, n = 25). The cross-sectional area (CSA) of the gastric antrum was measured at 0, 30, 60, 90, and 120 min (T = time). The gastric emptying rate (GER, GER=-AareaTn/AareaTn-30-1×100), GER/min (GER divided by the corresponding interval time), gastric content properties, Perlas grade at different time points, T120 gastric volume (GV), and GV per unit of body weight (GV/W) were evaluated. The risk of vomiting, reflux/aspiration, and type of anesthetic treatment were also evaluated. Results: The differences between the two groups in the CSA of the gastric antrum at each time point were statistically significant (p < 0.001). The CSAs of the gastric antrum in group M were lower than those in group S, and the greatest difference between the two groups occurred at T30 (p < 0.001). The differences between the two groups in GER and GER/min were also statistically significant (p < 0.001); those differences in group M were higher than those in group S, and the greatest differences between the two groups occurred at T30 (p < 0.001). There were no obvious change trends in the properties of the gastric contents and the Perlas grades in either group, and the differences between the two groups were not statistically significant (p = 0.97). The differences between the two groups in the GV and GV/W at T120 were statistically significant (p < 0.001), as was the risk of reflux and aspiration at T120 (p < 0.001). Conclusion: When metoclopramide was used in satiated emergency trauma patients, it accelerated gastric emptying within 30 min and reduced the risk of accidental reflux. However, a normal gastric emptying level was not achieved, which can be attributed to the delaying effect of trauma on gastric emptying.

Differences in preoperative gastric ultrasound findings in elderly compared to the mid-aged surgical patients: A retrospective observational study

This study aimed to compare gastric ultrasound assessments between young and elderly patients, to determine whether the cross-section area (CSA) cutoff values for elderly and young patients should be different, and to suggest CSA cutoff values for elderly patients. This study evaluated the data of 120 patients who underwent elective surgery under general anesthesia between July 2019 and August 2020. Demographic and gastric ultrasound assessment data were retrieved. Patients were divided into the elderly group (n = 58, age: ≥65 years) and young group (n = 62, age: <65 years). The CSAs in the supine and right lateral decubitus positions (RLDP), semiquantitative 3-point Perlas grade (grades 0, 1, and 2), and gastric volume (GV) were determined. CSAs according to different Perlas grades were compared between the 2 groups. To compare normally and non-normally distributed continuous data, Student t test and the Mann-Whitney U test were used, respectively. Categorical data were compared using the chi-square test or Fisher exact test, as appropriate. The receiver operating characteristic (ROC) curves were built for the CSAs to predict pulmonary aspiration. The CSA cutoff values for predicting a high risk of pulmonary aspiration in both the groups were determined. Among patients with Perlas grade 0, the CSAsupine (P = .002) and CSARLDP (P = .002) were greater in the elderly group than in the young group. The specificity, positive predictive value, and accuracy of the CSA decreased when the CSA cutoff value for the young group was applied to the elderly group. The CSA cutoff values for the elderly group were: CSAsupine, 6.92 cm2 and CSARLDP, 10.65 cm2. The CSA of the empty stomach was greater in elderly patients than in young patients. We suggest that the following CSA cutoff values should be used for predicting pulmonary aspiration risk in elderly patients: CSAsupine, 6.92 cm2 and CSARLDP, 10.65 cm2.

Perioperative Fluid Management and Volume Assessment

Fluid therapy is an integral component of perioperative care and helps maintain or restore effective circulating blood volume. The principal goal of fluid management is to optimize cardiac preload, maximize stroke volume, and maintain adequate organ perfusion. Accurate assessment of volume status and volume responsiveness is necessary for appropriate and judicious utilization of fluid therapy. To accomplish this, static and dynamic indicators of fluid responsiveness have been widely studied. This review discusses the overarching goals of perioperative fluid management, reviews the physiology and parameters used to assess fluid responsiveness, and provides evidence-based recommendations on intraoperative fluid management.

Ultrasound assessment of gastric contents and volume in patients undergoing endoscopic endonasal transsphenoidal surgery: a prospective observational study

Intraoperative ingestion of blood, cerebrospinal fluid, and irrigation fluid can lead to an increase in gastric volume, resulting in the potential risk of aspiration in patients after endoscopic endonasal transsphenoidal surgery (EETS). In this prospective observational study, we aimed to assess the volume of gastric contents in patients undergoing this neurosurgical procedure using ultrasound, and to determine the factors associated with volume change. Eighty-two patients diagnosed with pituitary adenoma were recruited consecutively. Semi-quantitative (Perlas scores: 0, 1 and 2) and quantitative (cross-sectional area, CSA) ultrasound assessments of the gastric antrum were performed immediately before and after surgery in the semi-recumbent and semi-recumbent right-lateral positions. Seven (8.5%) patients had antrum scores from preoperative grade 0 to postoperative grade 2; nine (11%) patients had antrum scores from preoperative grade 0 to postoperative grade 1. The mean ± standard deviation (SD) of increased gastric volume was 71.0 ± 33.1 mL and 236.5 ± 32.4 mL in postoperative grade 1 and 2 groups, respectively. Subgroup analysis showed that 11 (13.4%) patients (4 in grade 1 and all in grade 2) had postoperative estimated gastric volume > 1.5 mL kg^-1 (mean ± SD 3.08 ± 1.67, range 1.51-5.01 mL kg^-1). Logistic regression analysis revealed that older age, diabetes mellitus, and long surgical duration were independent risk factors for significant volume change (all P < 0.05). Our results showed a significant increase in gastric volume in some patients who underwent EETS. Bedside ultrasound measurements of gastric volume can be used to assess the postoperative aspiration risk, particularly in older diabetic patients with a longer surgical duration.

Prospective audit on fasting status of elective ambulatory surgery patients, correlated to gastric ultrasound

INTRODUCTION

Recent guidelines advocate a preoperative fasting interval of 6 h for solid food, 4 h for breast milk and 2 h for clear fluids. Long nil per mouth intervals give rise to complications and discomfort in the perioperative period. Gastric ultrasound is easily accessible and generates reliable information about gastric content.

PATIENTS AND METHODS

One hundred patients were offered a questionnaire regarding preoperative fasting. Important outcome measures were hour of last meal, last clear fluids intake, the source of preoperative information. Gastric ultrasound was performed in prone position and lateral decubitus.

RESULTS

The mean duration of fasting for solid food was 13h29 and 9h51 for clear fluids. 48% of patients were well aware of the correct fasting guidelines. The most frequent source of information was the preoperative phone call. Gastric ultrasound only found insignificant amounts of gastric content.

DISCUSSION

Too few patients are aware of the correct guidelines or fear complications and therefore adhere to the nil per mouth from midnight as most conservative measure. A phone call informing patients about the hour of surgery and allowing clear fluid intake until 2 h before surgery, is still not convincing enough. Some health care providers advise their patients the nil per mouth from midnight rule, due to risk of interfering with the operating room schedule.

CONCLUSION

It is still difficult to implement liberal intake of clear fluids according to current guidelines. Ambulatory surgery patients have long fasting intervals with decrease of subjective well-being and increased incidence of hunger and thirst.

Effect of facemask oxygenation with and without positive pressure ventilation on gastric volume during anesthesia induction in patients undergoing laparoscopic cholecystectomy or partial hepatectomy: a randomized controlled trial

BACKGROUND

Studies focusing on the relationship between gastric volume and facemask oxygenation without ventilation during apnea in anesthesia induction are scarce. This study compared the change in gastric volume during apnea in anesthesia induction using facemask ventilation and facemask oxygenation without ventilation in adults undergoing laparoscopic surgery.

METHODS

In this prospective, randomized, double-blinded trial, 70 adults undergoing laparoscopic surgery under general anesthesia were divided into two groups to receive facemask oxygenation with and without ventilation for 60 seconds after loss of consciousness. Before anesthesia induction and after endotracheal intubation, the gastric antral cross-sectional area was measured with ultrasound imaging. Arterial blood gases were tested at baseline (T1), after preoxygenation (T2), after loss of consciousness (T3), and before and after endotracheal intubation (T4 and T5, respectively).

RESULTS

Sixty patients were included (ventilation n = 30; non ventilation n = 30, 10 patients were excluded). The median [IQR] change of gastric antral cross-sectional area in ventilation group was significantly higher than in non ventilation group (0.83 [0.20 to 1.54] vs. 0.10 [- 0.11 to 0.56] cm₂, P = 0.001). At T4 and T5, the PaO₂ in ventilation group was significantly higher than in non ventilation group (T4: 391.83 ± 61.53 vs. 336.23 ± 74.99 mmHg, P < 0.01; T5: 364.00 ± 58.65 vs. 297.13 ± 86.95 mmHg, P < 0.01), while the PaCO₂ in non ventilation group was significantly higher (T4: 46.57 ± 5.78 vs. 37.27 ± 6.10 mmHg, P < 0.01; T5: 48.77 ± 6.59 vs. 42.63 ± 6.03 mmHg, P < 0.01) and the pH value in non ventilation group was significantly lower (T4: 7.35 ± 0.029 vs 7.42 ± 0.047, P < 0.01; T5: 7.34 ± 0.033 vs 7.39 ± 0.044, P < 0.01). At T4, the HCO₃^- in non ventilation group was significantly higher (25.79 ± 2.36 vs. 23.98 ± 2.18 mmol l^- 1, P < 0.01).

CONCLUSIONS

During apnoea, the increase in gastric volume was milder in patients undergoing facemask oxygenation without ventilation than with positive pressure ventilation.

TRIAL REGISTRATION

ChiCTR2100054193, 10/12/2021, Title: "Effect of positive pressure and non-positive pressure ventilation on gastric volume during induction of general anesthesia in laparoscopic surgery: a randomized controlled trial". Website: https://www.chictr.ogr.cn .

Unrestricted drinking before surgery: an iterative quality improvement study

Average pre-operative fasting times for clear liquids are many times longer than those specified in national and international guidelines. We sought to decrease fasting times by applying a quality management tool aimed at continuous improvement. Through the application of iterative 'plan-do-study-act' cycles, tools to reduce pre-operative liquid fasting times were developed and applied, the effects measured, analysed and interpreted and the conclusions used to inform the next plan-do-study-act cycle. The first step was the introduction of unrestricted drinking until the patient was called to the operating theatre, with training of anaesthetic staff, adaption of local standard procedures and verbal information for patients. This did not result in short liquid fasting times, median (IQR [range]) 12.0 (9.5-14.0 [0.8-23.5]) h. In the second cycle, fasting cards were introduced as a subliminal written training tool for staff, patients and their relatives. This enabled short liquid fasting times to be achieved for outpatients (2.6 (0.8-5.1 [0.3-16]) h) and pre-admission patients (3.4 (1.8-9.4 [0.2-17.2]) h), but not for inpatients (6.5 (2.0-11.7 [0.2-16.2]) h). The third cycle included lectures for ward staff, putting up information posters throughout the hospital, revision of all written materials and provision of screencasts on the homepage for staff and patients. This decreased median liquid fasting time to 2.1 (1.2-3.8 [0.4-18.8]; p &lt; 0.0001) h, with inpatients having the shortest fasting time of 1.4 (1.1-3.8 [0.4-18.8]) h. Repeated quality improvement cycles, adapted to local context, can support sustained reductions in pre-operative liquid fasting times.

Hard-Candy Consumption Does Not Have an Effect on Volume and pH of Gastric Content in Patients Undergoing Elective Gastrointestinal Endoscopic Procedures: A Randomized Controlled Trial

Purpose

This study aimed to determine the effect of hard candies on gastric content volume and pH in patients undergoing elective esophagogastroduodenoscopy and colonoscopy. Additionally, the study evaluated the difficulty of the procedure, complications, and satisfaction levels of the endoscopist and patient.

Patients and Methods

A randomized controlled study equally recruited 108 outpatients to candy and control groups. The patients in the candy group could consume sugar-free candies within 2 hours before anesthesia, while the controls remained fasted. The endoscopic procedure began under topical pharyngeal anesthesia and intravenous sedation. A blinded endoscopist suctioned the gastric volume through an endoscope. A blinded anesthesia provider tested the gastric pH with a pH meter. The primary outcome variables were gastric volume and pH. The secondary outcome variables were complications, the difficulty of the procedure, and endoscopist and patient satisfaction.

Results

The characteristics of both patient groups were comparable. The mean gastric volume of the candy group (0.43 [0.27-0.67] mL/kg) was not significantly different from that of the control group (0.32 [0.19-0.55] mL/kg). The gastric pH of both groups was similar: 1.40 (1.10-1.70) for the candy group and 1.40 (1.20-1.90) for the control group. The procedure-difficulty score of the candy group was higher than that of the control group. The satisfaction scores rated by the endoscopist and the patients in both groups were comparable. In addition, most endoscopists and patients in the candy and control groups reported being "very satisfied". No complications were observed in either group.

Conclusion

Hard candies did not affect gastric volume or pH. Elective gastrointestinal endoscopic procedures in adult patients who preoperatively consume candies could proceed to prevent delays and disruption of workflows.

Preoperative fasting: exploring guidelines and evidence to ensure consistent, high-quality care

Many nurses will still be familiar with the instruction 'nil by mouth from midnight' traditionally given to patients preparing to undergo surgery. National and international guidelines now promote much shorter preoperative fasting times, encapsulated in the '2-4-6 rule' - two hours for clear fluids, four hours for breast milk and six hours for solids. The latest evidence appears to show that these fasting times are in need of revision. Furthermore, there are inconsistencies in how guidelines are implemented. This article explores the guidelines and literature on preoperative fasting in adults and children to determine what the evidence is and what changes could be made to ensure consistent, high-quality patient care.

Qualitative and quantitative gastric ultrasound assessment in highly skilled regional anesthesiologists

BACKGROUND

Pulmonary aspiration is a major complication in anesthesia, and various studies have shown that gastric sonography can reliably provide valuable information relative to both the qualitative and quantitative aspects of gastric content. This study aimed to determine the accuracy of ultrasound assessment of gastric content compared between two novice anesthesiologist gastric sonographers.

METHODS

This prospective cohort study of two anesthesiologists learning to perform qualitative and quantitative ultrasound assessment of gastric content on healthy volunteers was conducted at Siriraj Hospital (Bangkok, Thailand). This trial was registered with ClinicalTrials.gov (reg. no. NCT04760106).

RESULTS

Of the 50 enrolled participants, three were excluded due to study protocol violation. Each anesthesiologist performed a qualitative assessment on 47 participants for an overall total of 94 scans. There were 15 males and 32 females (age 42 ± 11.7 years, weight 61.2 ± 13.1 kg, height 160.7 ± 7.3 cm, and BMI 23.6 ± 4.3 kg/m²). The overall success rate for all gastric content categories was approximately 96%. From antral cross-sectional area measurement, as the ingested volume increased, there was a tendency toward increased deviation from the actual ingested volume. Interrater agreement between anesthesiologists was analyzed using intraclass correlation coefficients (ICCs). A larger fluid volume was found to be associated with a lower level of agreement between the two anesthesiologists. The ICCs were 0.706 (95% CI: -0.125 to 0.931), 0.669 (95% CI: -0.254 to 0.920), 0.362 (95% CI: -0.498 to 0.807) for the 100 ml, 200 ml, and 300 ml fluid volumes, respectively. The mean duration to perform an ultrasound examination for each gastric content category and for the entire examination did not differ significantly between anesthesiologists (p > 0.05).

CONCLUSION

Our results indicate that qualitative ultrasound assessment of gastric content is highly accurate and can be easily learned. In contrast, quantification of gastric volume by novice gastric sonographers is more complex and requires more training.

TRIAL REGISTRATION

ClinicalTrials.gov no. NCT04760106 Date registered on Feb 11, 2021. Prospectively registered.

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.

Point-of-Care Ultrasound to Assess Gastric Content in Pediatric Emergency Department Procedural Sedation Patients

OBJECTIVES

There is debate regarding the timing of procedural sedation and analgesia (PSA) in relation to fasting status. Point-of-care ultrasound (POCUS) provides the ability to measure gastric content and is being used as a surrogate for aspiration risk in anesthesia. We sought to evaluate the gastric content of pediatric emergency department (PED) patients undergoing PSA using POCUS.

METHODS

We performed a prospective observational study using a convenience sample of pediatric patients undergoing PSA between July 1, 2018, and June 30, 2019. Following a brief history, gastric content was measured using POCUS in both supine and right lateral decubitus positions at 2-hour intervals until the time of PSA. Qualitative content and calculated volume were classified based on the Perlas Model of anesthesia "Risk" assessment.

RESULTS

Ninety-three patients were enrolled with 61.3% male and mean age of 6.5 years. Gastric content was determined in 92 patients. There were 79.3% that had "high risk" content at the time of PSA, with a median fasting time of 6.25 hours and no serious adverse events. Fasting duration had a weak to moderate ability to predict "risk" category (area under the curve = 0.73), with no patient (n = 17) who underwent multiple evaluations awaiting PSA progressing from "high" to "low risk."

CONCLUSIONS

The majority of PED patients undergoing PSA at our institution had "high risk" gastric content with no clinically significant change occurring during serial evaluations. This calls into question the utility of delaying PSA based upon fasting status and lends support to a more comprehensive risk-benefit approach when planning pediatric PSA.

Pre-induction Ultrasonographic Evaluation of Gastric Residual Volume in Elective Gastrointestinal Cancer Surgeries

Pulmonary aspiration of gastric contents during elective surgery remains a major cause of airway-related mortality and morbidity. The preoperative fasting times for solids and liquids have been standardized across various anesthesia society guidelines. Enhanced Recovery After Surgery (ERAS) guidelines now advocate liberal clear fluid intake with carbohydrate loading up to 2 h preoperatively. The aim of the study was to assess whether practicing both ASA fasting guidelines and ERAS protocol makes the patients prone to a full stomach. The supine position standard curvilinear ultrasound probe (2-5 MHz) with Sonosite M-Turbo ©system was used to obtain the images. Gastric residual volume (GRV) was derived from the cross-sectional area (CSA) using the Perlas and colleagues model. A total of 102 patients were recruited and analyzed. The mean age and BMI were 50.65 years ± 13.35 years and 22.23 kg/m² ± 3.7 kg/m², respectively. A total of four patients (3.92%) had gastric volume > 1.5 ml/kg; out of these four patients, three were female and one was male. We did not observe any case of pulmonary aspiration in any of our patients. In conclusion, even though for elective surgeries, the current fasting guidelines are adequate, these findings cannot be extrapolated to patients with risk factors for high gastric residual volume where further studies need to be performed.

Fasting does not guarantee empty stomach in the intensive care unit: A prospective ultrasonographic evaluation (The NUTRIGUS study)

BACKGROUND

In the intensive care unit (ICU), a fasting period is usually respected to avoid gastric aspiration during airway management procedures. Since there are no recognised guidelines, intensive care physicians balance the aspiration risk with the negative consequences of underfeeding. Our objective was to determine the impact of fasting on gastric emptying in critically ill patients by using gastric ultrasound.

MATERIAL AND METHODS

Among the 112 patients that met the inclusion criteria, 100 patients were analysed. Gastric ultrasonography was performed immediately before extubation. Patients with either 1/ an absence of visualised gastric content (qualitative evaluation) or 2/ a gastric volume < 1.5 mll/kg in case of clear fluid gastric content (quantitative evaluation) were classified as having an empty stomach.

MAIN FINDINGS

In our study, twenty-six (26%) patients had a full stomach at the time of extubation. The incidence of full stomach was not significantly different between patients who fasted < 6 h or patients who fasted ≥ 6 h. Among the 57 patients receiving enteral nutrition (EN) within the last 48 h, there was no correlation between the duration of EN interruption and the GAA. The absence of EN was not associated with an empty stomach.

CONCLUSION

At the time of extubation, the incidence of full stomach was high and not associated with the fasting characteristics (duration/absence of EN). Our results support the notions that fasting before airway management procedures is not a universal paradigm and that gastric ultrasound might represent a useful tool in the tailoring process. CLINICALTRIALS.GOV: NCT04245878.

Reinforcing the valuable role of gastric ultrasound for volume and content assessment: an observational study

BACKGROUND

Pulmonary aspiration is one of the most important complications in anesthesiology. Assessment of gastric content by ultrasound is a good method to quantify gastric volume and to determine the risk of intraoperative pulmonary aspiration. The aim of this study is to determine the accuracy of the gastric ultrasonography in the qualitative analysis of gastric content, mainly in the analysis of small amounts of liquid content.

METHODS

Gastric ultrasound was performed to 36 patients before upper gastrointestinal endoscopy (UGI), making two longitudinal scans at the epigastric level, one in supine position and the other in right lateral decubitus position, measuring two diameters and the area of the gastric antrum and assessing the content characteristics determining whether it was an empty stomach or contained fluid or solid content. Subsequently, the ultrasound findings were compared with UGI findings.

RESULTS

Gastric areas were analyzed by the trace and the lengths of the craniocaudal and anteroposterior axes concluding that there are no significant differences between the two methods. No statistically significant difference was found between UGI and US assessment technics. No statistically significant difference was found between the estimated volume by UGI and US.

CONCLUSIONS

Though our study has some limitations, qualitative analysis of gastric content using ultrasound followed by endoscopy enabled the conclusion that there are no differences in the qualitative assessment regarding these two techniques, supporting the important role of point-of-care gastric ultrasound (POCGUS) in the assessment of pulmonary aspiration risk by the anesthesiologist in the perioperative period.

A protocol implementation to determine aspiration risk in patients with multiple risk factors for gastroparesis

Patients with risk factors for gastroparesis are at increased risk for aspiration into the tracheobronchial tree. Current American Society of Anesthesiologists fasting guidelines use subjective measures to determine aspiration risk. A gastric ultrasound protocol can identify patients with risk factors for gastroparesis and determine the need to perform a point-of-care gastric ultrasound to objectively assess gastric antral contents. This enables the anaesthesia provider to assess patients at increased risk for aspiration. Additionally, many patients who present for surgery with risk factors for gastroparesis have an empty gastric antrum. Thus, the gastric ultrasound protocol checklist saves time and manpower requirements of anaesthesia staff without impacting patient safety or perioperative efficiency. A convenience sample of 40 patients consented for surgery was assessed using a screening tool to identify those at risk for gastroparesis and possible aspiration. Patients deemed at risk received a gastric ultrasound examination to evaluate for the presence of gastric contents. Over 12% of these patients had solid food gastric contents on exam. All patients with solid food gastric contents had an American Society of Anesthesiologists Physical Status Classification of 3 or higher, and two or more risk factors for gastroparesis.

[Preoperative fluid fasting : Establishment of a liberal fluid regimen using fasting cards]

BACKGROUND

Preoperative fasting times for clear liquids surpass by far the recommendations of the specialist societies. The aim of this study was to introduce a liberal regimen for preoperative fasting of clear liquids using fasting cards as a training tool and to evaluate the implementation.

MATERIAL AND METHODS

We developed a liberalized regimen of preoperative clear fluid fasting times, which allows patients to drink water, apple juice, tea and coffee until being called to the operating theatre. Each patient receives a bed-side fasting card with written information specifying fasting times for solid food and liquids. Patients who are allowed to drink water, apple juice, tea and coffee until the call to the operating theatre receive a blue fasting card. Patients with coexisting diseases or conditions that can affect gastric emptying or who need longer fasting times because of the surgical procedure get a yellow fasting card on which fasting times for fluids and solids can be documented individually. Patients who need to be nil per os (for example patients with ileus or bowel obstruction, emergency care) receive a red fasting card. On the back of the card the information is written in English, Turkish, Russian and Arabic. After a period of 8 months all surgical ward managers were asked to complete a questionnaire to assess the implementation of the new fasting regimen.

RESULTS

The response rate of the questionnaire was 100%. Without exception all interviewees would recommend the use of our liberalized fasting regimen. Almost all would also support the implementation of fasting cards. Out of 11 wards 9 found that patients were more relaxed and asked for intravenous fluids less often while waiting for surgery. The multilingual nature of the cards makes it easier to deal with patients who do not speak German. All ward managers consistently approved the new regimen in the event they themselves would need an operation. In order to make the fasting cards also usable in the future for rescue centers and functional units, such as endoscopy, echo or cardiac catheters, the reasons for fasting on the blue and yellow cards have been extended to operation or examination and on the red card to illness, operation or upcoming examination.

CONCLUSION

Patients should be allowed to drink water and hypotonic clear fluids until shortly before an operation to avoid complications of overly long fasting times. Fasting cards help to implement this by providing easy to understand information for patients and healthcare workers. This concept should be clearly structured, transparent for everyone, written down and brought to the attention of the patient without a language barrier.

Ultrasound-guided assessment of gastric residual volume in patients receiving three types of clear fluids: A randomised blinded study

Background and Aims:

Ultrasonography (USG) is used to evaluate gastric residual volume (GRV); however, this technique may have inter-assessor variability. This study aimed to measure GRV in three groups of fasted patients 2 h after they received 200 mL of water, clear apple juice or apple-flavoured oral rehydration solution (ORS) and to determine inter-assessor reliability of USG-guided GRV measurement.

Methods:

We randomised 90 adult patients planned for elective cancer surgery, with no risk factors for delayed gastric emptying, to receive 200 mL of water, clear apple juice or apple-flavoured ORS after overnight fasting. Two hours later, two blinded assessors (a trained anaesthesiologist and a radiologist) independently determined USG-guided GRV. The primary outcome was GRV measured by the radiologist. The secondary outcome was inter-assessor correlation and agreement in GRV measurements.

Results:

There was no statistically significant difference in median GRV between groups (apple-flavoured ORS 74.8 mL, apple juice 63.7 mL, and water 62.1 mL, P = 0.11). We found poor correlation between measurements of radiologist and anaesthesiologist (Intra-class correlation coefficient 0.3, 95% confidence intervals 0.09 to 0.48, P value 0.002). The average (mean) bias was 5.4 mL (standard deviation 42.3 mL) and the 95% limits of agreement were -79.2 ml to +90 ml.

Conclusion:

Patients receiving 200 mL of water, clear apple juice or apple-flavoured ORS had comparable GRV after 2 h. There was poor correlation and agreement between GRV measurements of different assessors, indicating that more training may be required for anaesthesiologists to attain proficiency in the quantitative assessment of GRV.

Anaesthesiologists' clinical judgment accuracy regarding preoperative full stomach: Diagnostic study in urgent surgical adult patients

BACKGROUND

In urgent situations, preoperative full stomach assessment mostly relies on clinical judgment. Our primary objective was to assess the diagnostic performance of clinical judgment for the preoperative assessment of full stomach in urgent patients compared to gastric point-of-care ultrasound (PoCUS). Our secondary objective was to identify risk factors associated with PoCUS full stomach in urgent patients.

METHODS

We led a prospective observational study at our Hospital, between January and July 2016. Adult patients admitted for urgent surgery were eligible. Patients with altered gastric sonoanatomy, interventions reducing stomach content, impossible lateral decubitus were excluded. Clinical judgment and risk factors of full stomach were collected before gastric PoCUS measurements. Ultrasonographic full stomach was defined by solid contents or liquid volume ≥ 1.5 ml kg^-1. Diagnostic performance was assessed through sensitivity, specificity, accuracy, positive and negative predictive value.

RESULTS

The prevalence of clinical and PoCUS full stomach in 196 included patients was 29% and 27%, respectively. Positive and negative predictive values were 42% (95% CI: 32.3-52.6%) and 79% (95% CI: 74.9-83.4%), respectively. Patients with PoCUS full stomach were clinically misdiagnosed in 55% of cases. PoCUS full stomach was associated with abdominal or gynaecological-obstetrical surgery (OR 3.6, 95% CI: 1.5-8.8, P < 0.01) but not with fasting durations. Positive solid intake after illness onset with respect to 6-h solid fasting rule was associated with PoCUS low-risk gastric content (OR 0.4, 95% CI: 0.2-0.9, P = 0.03).

CONCLUSIONS

Clinical judgment showed poor-to-moderate performance in urgent surgical patients for the diagnosis of full stomach. Gastric PoCUS should be used to assess risk of full stomach in this population.

Pulmonary Aspiration During Induction of General Anesthesia

Perioperative pulmonary aspiration of gastric contents can induce complications of varying severity, including aspiration pneumonitis or pneumonia, which may be lethal. A 34-year-old man with no significant medical history presented to Okayama University Hospital for extraction of the third molars and incisive canal cystectomy under general anesthesia. He experienced pulmonary aspiration of clear stomach fluid during mask ventilation after induction. After aspiration occurred, the patient was immediately intubated, and suctioning was performed through the endotracheal tube (ETT). An anteroposterior (AP) chest radiograph was obtained that demonstrated atelectasis in the left lower lobe, in addition to increased peak airway pressures being noted, although SpO2 remained at 96% to 99% at an FiO2 of 1.0. The decision was made to proceed, and the scheduled procedures were completed in approximately 2 hours. A repeat AP chest radiograph obtained at the end of the operation revealed improvement of the atelectasis, and no residual atelectasis was observed on the next day. Although the patient reported following standard preoperative fasting instructions (no fluids for 2 hours preoperatively), more than 50 mL of clear fluid remained in his stomach. Because vomiting can occur despite following NPO guidelines, the need for continued vigilance by anesthesia providers and proper timely management is reinforced.

Ultrasonographic evaluation of gastric content and volume: a systematic review

SUMMARY OBJECTIVE: Bronchoaspiration of gastric content is associated with high morbidity and mortality, but evaluating this complication is a difficult task. However, gastric ultrasonography can safely assess gastric content and prevent bronchoaspiration. Therefore, a systematic review was performed in order to verify the efficacy of ultrasonography in the qualitative and quantitative analyses of gastric content. METHODS: A literature review of articles published between 2009 and 2019 in the PubMed and LILACS databases was conducted using combinations of the keywords “gastric ultrasound,” “gastric emptying,” and “gastric content.” RESULTS: Of the 20 articles found, 19 chose the antral region as the best site for qualitative analysis of the gastric content. Regarding quantitative measurement, the most commonly used method to calculate the gastric volume in eight articles was the formula “Gastric Volume = 27 + (14.6 × ATAG) − (1.28 × Age),” in which the area of the transverse section of the gastric antrum (ATAG) could also be calculated by the largest antral diameters or by free tracing. CONCLUSION: An efficient evaluation of the gastric content can be performed by ultrasonography of the antral region, contributing to greater safety in the clinical management of patients with increased risk for bronchoaspiration during airway management.

Oral carbohydrate solution cause an inflammatory response when aspirated into the lungs in mice

PURPOSE

Many studies have been published on the beneficial effects of oral carbohydrate solutions (OCS) administered prior to surgery. However, the risk of pulmonary aspiration cannot be excluded in all patients undergoing anesthesia. But, there are few studies on the safety of OCS at lung aspiration.

METHODS

Experiments were conducted with mice (Nine- to ten-week-old male BALB/c mice weighted 23-26 g). Lung aspiration was performed by intratracheal administration of OCS and its major constituents, fructose and maltodextrin. Bronchoalveolar lavage fluid (BALF) was collected 3 and 24 h after lung aspiration. The level of Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and macrophage inflammatory protein-2 (MIP-2) were measured in BALF. The total white blood cell, neutrophil counts, wet to dry ratio and histological examination were performed in BALF and lung tissue, respectively, at 24 h after aspiration.

RESULTS

The OCS increased the level of TNF-α, IL-6 and MIP-2 at 3 h and the neutrophil count at 24 h in BALFs, compared to a phosphate-buffered saline (PBS) group. The increase in IL-6 level induced by OCS was maintained for 24 h. The OCS also increased the number of white blood cells and the percentage of neutrophils in BALFs. Compared to fructose, maltodextrin significantly increased the production of MIP-2 in BALFs. OCS and maltodextrin also increased neutrophil recruitment in lung tissue.

CONCLUSION

Aspiration of OCS may cause inflammation of the lungs. The preoperative use of OCS may require caution under specific clinical conditions, such as patients at risk of lung aspiration.