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

ASRA pain medicine narrative review and expert practice recommendations for gastric point-of-care ultrasound to assess aspiration risk in medically complex patients undergoing regional anesthesia and pain procedures

Gastric point-of-care ultrasound (POCUS) may offer clinical value in assessing aspiration risk among medically complex patients undergoing regional anesthesia and pain procedures. While the American Society of Anesthesiologists (ASA) preoperative fasting guidelines primarily apply to healthy individuals, medically complex populations often present with differing gastric emptying and aspiration risk. This narrative review, conducted by the American Society of Regional Anesthesia and Pain Medicine (ASRA-PM), adhered to PRISMA guidelines and was registered with PROSPERO. It focused on seven medically complex patient groups: those who are pregnant, obese, diabetic, have gastroesophageal reflux disease (GERD), are receiving emergency care, are enterally fed, or are taking GLP-1 receptor agonists (GLP-1RA). Study quality was assessed using the Mixed Methods Appraisal Tool (MMAT). Practice recommendations were developed using an iterative expert consensus process, with final recommendations based on evidence strength, clinical relevance, and expert agreement. Findings support the use of gastric POCUS in patients in active labor, those undergoing urgent cesarean sections, and those with diabetes. Conditional support is given for obesity, emergency care, enteral feeding, and GLP-1RA use. Routine use is not recommended in non-laboring pregnancies, elective cesarean delivery, or GERD. While gastric POCUS may aid with aspiration risk evaluation, its use should complement clinical judgment. Implementation may be limited by practical and training constraints, requiring individualized decision-making. These recommendations serve as a foundation for future research and potential clinical guideline development. PROSPERO registration number: CRD42023445927.

A machine learning stacking model accurately estimating gastric fluid volume in patients undergoing elective sedated gastrointestinal endoscopy

BACKGROUND

The current point-of-care ultrasound (POCUS) assessment of gastric fluid volume primarily relies on the traditional linear approach, which often suffers from moderate accuracy. This study aimed to develop an advanced machine learning (ML) model to estimate gastric fluid volume more accurately.

METHODS

We retrospectively analyzed the clinical data and POCUS data (D1: craniocaudal diameter, D2: anteroposterior diameter) of 1386 patients undergoing elective sedated gastrointestinal endoscopy (GIE) at Nanjing First Hospital to predict gastric fluid volume using ML techniques, including six different ML models and a stacking model. We evaluated the models using the adjusted Coefficient of Determination (R2), mean absolute error (MAE) and root mean square error (RMSE). The SHapley Additive exPlanations (SHAP) method was used to interpret the importance of the variables. Finally, a web calculator was constructed to facilitate its clinical application.

RESULTS

The stacking model (Linear regression + Multilayer perceptron) performed best, with the highest adjusted R2 of 0.718 (0.632 to 0.804). The mean prediction bias was 4 ml (MAE: 4.008 (3.68 to 4.336)), which is better than that of the linear model. D1 and D2 ranked high in the SHAP plot and performed better in the right lateral decubitus (RLD) than in the supine position. The web calculator can be accessed at https://cheason.shinyapps.io/Stacking_regressor/.

CONCLUSION

The stacking model and its web calculator can serve as practical tools for accurately estimating gastric fluid volume in patients undergoing elective sedated GIE. It is recommended that anesthesiologists measure D1 and D2 in the patient's RLD position.

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.

Effectiveness of ultrasonic measurement for the hyomental distance and distance from skin to epiglottis in predicting difficult laryngoscopy in children

OBJECTIVES

Studies have shown that some ultrasonic indicators can predict difficult airways in adults to an extent. However, whether ultrasonic parameters can be used to predict difficult airways in children is unclear. This study investigated the predictive value of several ultrasonic indices for difficult laryngoscopy (DL) in children.

METHODS

Pediatric patients aged 5 to 12 years who underwent endotracheal intubation under general anesthesia were enrolled. The hyomental distance in the extended position (HMDE), tongue thickness, midsagittal tongue cross-sectional area, tongue width, and distance from skin to epiglottis (DSE) were measured by ultrasound before anesthesia. The study end point was DL. The receiver operating characteristic curve was used to evaluate the predictive value of each parameter.

RESULTS

Three hundred and ten children were included in the final analysis, and fifteen (4.8%) children had DL. The shortened HMDE assessed by ultrasound could help identify children aged 5 to 12 years with DL (5-8 years: area under the curve (AUC) 0.74, sensitivity 0.88, specificity 0.60; 9-12 years: AUC 0.72, sensitivity 0.71, specificity 0.83). An increased DSE could help identify children aged 5 to 8 years with DL (AUC 0.76, sensitivity 0.88, specificity 0.69).

CONCLUSIONS

Ultrasonic measurement of the HMDE can be used to predict DL in children aged 5 to 12 years. The DSE measured by ultrasound can be used to predict DL in children aged 5 to 8 years.

CLINICAL RELEVANCE STATEMENT

The hyomental distance and the distance from skin to epiglottis measured by ultrasound can be used to predict difficult laryngoscopy in children, which can help reduce serious complications caused by unanticipated difficult airways in children during anesthesia.

KEY POINTS

• Ultrasonic measurement of the hyomental distance in the extended position may be an effective predictor of difficult laryngoscopy in children aged 5 to 12 years. • The distance from skin to epiglottis measured by ultrasound can be used to predict difficult laryngoscopy in children aged 5 to 8 years. • Preoperative airway assessment using ultrasound can be effectively applied in children and has a great application prospect.

The role of gastric ultrasound in anaesthesia for emergency surgery: A review and clinical guidance

BACKGROUND

The timing and technique of anaesthesia are challenging in patients with a history of recent food intake. The presence of gastric contents increases the risk of aspiration, potentially resulting in acute lung injury, pneumonia, or death. Delayed gastric emptying complicates the estimation of aspiration risk. Surprisingly, there are no fasting guidelines for emergency surgery. Point-of-care gastric ultrasound is a time-efficient, cost-efficient and accurate bedside tool with which to estimate residual gastric content and to guide decision-making in airway management and timing of general anaesthesia. This review summarises the prevailing concepts of ultrasound-guided gastric content assessment for emergency surgery.

METHODS

Medline and Embase databases were searched for studies using ultrasound for the evaluation of gastric content in adults scheduled for emergency surgery.

RESULTS

Five prospective observational studies representing 793 emergency surgery patients showed that the incidence of 'full stomach' was between 18 and 56% at the time of induction. Risk factors for a full stomach before emergency surgery were abdominal or gynaecological/obstetric surgery, high body mass index and morphine consumption. No correlation between preoperative fasting time and the presence of a full/empty stomach was found. No deaths due to aspiration were reported.

CONCLUSION

The preoperative presence of gastric content before emergency surgery is high and the estimates used for clinical management are unreliable. This review demonstrates that gastric ultrasound is a valuable tool for evaluating gastric content. A flow chart for medical decision-making using gastric ultrasound before emergency surgery was developed to assist in clinical decision-making. The validity and practical applicability should be assessed in future studies.

Ultrasound assessment of gastric contents in children before general anaesthesia for acute appendicitis

There is increasing evidence that a minority of adults with acute appendicitis have gastric contents, posing an increased risk of pulmonary aspiration. This study aimed to evaluate the proportion of children with acute appendicitis who have gastric contents considered to pose a higher risk of pulmonary aspiration. We analysed point-of-care gastric ultrasound data routinely collected in children before emergency appendicectomy in a specialist paediatric hospital over a 30-month period. Based on qualitative and quantitative antral assessment in the supine and right lateral decubitus positions, gastric contents were classified as 'higher-risk' (clear liquid with calculated gastric fluid volume > 0.8 ml.kg^-1 , thick liquid or solid) or 'lower-risk' of pulmonary aspiration. The 115 children studied had a mean (SD) age of 11 (3) years; 37 (32%; 95%CI: 24-42%) presented with higher-risk gastric contents, including 15 (13%; 95%CI: 8-21%) with solid/thick liquid contents. Gastric contents could not be determined in 13 children as ultrasound examination was not feasible in the right lateral decubitus position. No cases of pulmonary aspiration occurred. This study shows that gastric ultrasound is feasible in children before emergency appendicectomy. This technique showed a range of gastric content measurements, which could contribute towards defining the risk of pulmonary aspiration.

Point-of-Care Ultrasound for the Trauma Anesthesiologist

Purpose of Review

With advances in technology and availability of handheld ultrasound probes, studies are focusing on the perioperative care of patients, but a limited number specifically on trauma patients. This review highlights recent findings from studies using point of care ultrasound (POCUS) to improve the care of trauma patients.

Recent Findings

Major findings include the use of POCUS to assess volume status of trauma patients upon arrival to measure the major vasculature. Additionally, several studies have advanced the use of POCUS to identify pneumothorax in trauma patients. Finally, the ASA POCUS certification and ASRA expert guidelines are examples of international organizations establishing guidelines for utilization and training of anesthesiologists in the field of POCUS, which will be discussed.

Summary

Despite the COVID-19 pandemic, and considerable resources being diverted to fight this global healthcare crisis, advances are being made in utilization of POCUS to aid the care of trauma patients.

Ultrasound assessment of gastric contents prior to placental delivery: A prospective multicentre cohort study

BACKGROUND

There is ongoing debate regarding the optimal general anaesthetic technique for manual removal of the placenta after vaginal delivery. Using ultrasound examination of the gastric antrum, this study aimed to assess the change in gastric contents during vaginal delivery and to determine the prevalence of stomach at risk for pulmonary aspiration in the immediate postpartum period before placental delivery.

METHODS

In this prospective multicentre cohort study, antral ultrasonography was performed at full cervical dilatation within the thirty minutes preceding the beginning of expulsive efforts and after vaginal birth, before placental delivery. High-risk gastric content was defined as the visualisation of any solid content in the antrum or antral cross-sectional area in the semi-recumbent position (SR-CSA) > 608 mm².

RESULTS

Twenty-six women were included and analysed. There was a significant decrease in both the proportion of patients with solid gastric content and the SR-CSA between the two-ultrasound examinations. Twenty-one patients (80.8%) exhibited a decrease in the SR-CSA during vaginal delivery. The prevalence of stomach at risk for pulmonary aspiration was significantly lower after vaginal delivery than before vaginal delivery (23.1% vs. 57.7%, P = 0.0004).

CONCLUSION

Our results suggest that gastric emptying is at least partially preserved during vaginal birth. Nevertheless, almost a quarter of women did have high-risk gastric content in the immediate postpartum period. Point-of-care antral ultrasonography may be of interest for the fast assessment of the gastric content status when a general anaesthesia is required for manual removal of retained placenta.

Assessing gastric contents in children before general anesthesia for acute extremity fracture: An ultrasound observational cohort study

STUDY OBJECTIVE

Children with acute extremity fractures are commonly considered to be at risk of pulmonary aspiration of gastric contents during the induction of anesthesia. This study aimed to evaluate the proportion of such children with high-risk gastric contents using preoperative gastric ultrasound.

DESIGN

Prospective observational cohort study.

SETTING

Specialist pediatric center over a 30-month period.

PATIENTS

Children undergoing surgery within 24 h of an acute extremity fracture.

INTERVENTIONS

None.

MEASUREMENTS

According to preoperative qualitative and quantitative ultrasound analysis of the antrum in the supine and right lateral decubitus positions, gastric contents were classified as high-risk (clear liquid with calculated gastric fluid volume > 0.8 mL.kg^-1, thick liquid, or solid) or low-risk. Factors associated with high-risk gastric contents were identified by multivariable analysis.

MAIN RESULTS

Forty-one children (37%; 95% CI: 28-47) of the 110 studied (mean(SD) age: 10(3) years) presented with high-risk gastric contents, including 26 (24%; 95% CI: 16-33) with solids/thick liquid contents. Scanning in the supine position alone allowed a diagnosis of high-risk gastric contents in 23 children out of the 63 for whom right lateral decubitus positioning was unfeasible. Gastric contents remained undetermined in 41 children, including one with a non-contributory gastric US (antrum non-visualized). Proximal limb fractures (OR: 2.5; 95% CI: 1.0-6.2), preoperative administration of opioids (OR: 3.9; 95% CI: 1.1-13), and the absence of bowel sounds (OR: 8.0; 95% CI: 1.4-44) were associated with high-risk gastric contents. Performing surgery the day following the trauma was a protective factor (OR: 0.1; 95% CI: 0.0-0.6). No cases of pulmonary aspiration occurred.

CONCLUSIONS

At least one-third of children with an acute isolated extremity fracture had preoperative gastric contents identified as high risk for pulmonary aspiration. Although preoperative history can guide anesthetic strategy in this population, ultrasound allowed clear stratification of the risk of aspiration in most cases.