Ultrasound Assessment Of Gastric Volume Research Articles

Ultrasound Assessment of Gastric Volume in Parturients After High-flow Nasal Oxygen Therapy

(Anesth Analg. 2023;137:176–181) High-flow nasal oxygen (HFNO) therapy is a preferred method of respiratory support for pregnant women but concerns have been raised for gastric complications because of the positive airway pressure. Pregnancy causes physiological changes that can increase the risk of oxygen insufflation into the stomach, as well as the risk of aspiration. Aspiration risk can be determined by ultrasound assessment of gastric volume and antral cross-sectional area (CSA). This study was designed to assess the safety of HFNO therapy by examining changes in antral CSA and gastric volume via ultrasonography before and after HFNO administration, with a hypothesis that 20 minutes of HFNO therapy would increase gastric volume by 50%.

Preoperative Fasting of Eight Hours Provide Better Gastric Emptying: Ultrasound Assessment of Gastric Volume.

Preoperative fasting is a common practice to decrease perioperative aspiration risk. The American Society of Anesthesiologists (ASA) recommends preoperative fasting of 8 hours after a full meal. ASA preoperative fasting recommendation is based on the Western diet. A typical Western diet has a higher fat content than Asian standard solid meals. This study aimed to analyze intragastric volume with ultrasound after 6-hour and 8-hour fasting after an Asian traditional solid meal. This cohort study recruited 37 subjects from January to February 2019. Subjects were patients scheduled for elective non-digestive surgery and planned for preoperative fasting of 8 hours. Before preoperative fasting, all subjects consumed standard Asian meals. We performed an ultrasound of the gastric antrum during the relaxation phase after two contractions. After a good image was acquired, the cross-sectional area and gastric volume (GV) were calculated. GV was grouped based on a border value of 1.5 mL/kg. GV 6 hours after solid intake was 30.93 (1.60-205.25) mL, and GV 8 hours after solid intake was 16.34 (0.73-62.49) mL (P = 0.002). After 6 hours, 5.4% of the subjects had a GV above 1.5 mL/ kg, while after fasting for 8 hours, the GV of all subjects was below 1.5 mL/kg. Age was correlated moderately and negatively with the GV of 6 hours and 8 hours fasting (P < 0.001, correlation coefficient = -0.610, and P < 0.001, correlation coefficient = -0.580). Intragastric volume 8 hours after a standard Asian meal intake was lower than 6 hours after a traditional Asian meal.

Preoperative Fasting of Eight Hours Provide Better Gastric Emptying: Ultrasound Assessment of Gastric Volume.

Preoperative fasting is a common practice to decrease perioperative aspiration risk. The American Society of Anesthesiologists (ASA) recommends preoperative fasting of 8 hours after a full meal. ASA preoperative fasting recommendation is based on the Western diet. A typical Western diet has a higher fat content than Asian standard solid meals. This study aimed to analyze intragastric volume with ultrasound after 6-hour and 8-hour fasting after an Asian traditional solid meal. This cohort study recruited 37 subjects from January to February 2019. Subjects were patients scheduled for elective non-digestive surgery and planned for preoperative fasting of 8 hours. Before preoperative fasting, all subjects consumed standard Asian meals. We performed an ultrasound of the gastric antrum during the relaxation phase after two contractions. After a good image was acquired, the cross-sectional area and gastric volume (GV) were calculated. GV was grouped based on a border value of 1.5 mL/kg. GV 6 hours after solid intake was 30.93 (1.60-205.25) mL, and GV 8 hours after solid intake was 16.34 (0.73-62.49) mL (P = 0.002). After 6 hours, 5.4% of the subjects had a GV above 1.5 mL/ kg, while after fasting for 8 hours, the GV of all subjects was below 1.5 mL/kg. Age was correlated moderately and negatively with the GV of 6 hours and 8 hours fasting (P < 0.001, correlation coefficient = -0.610, and P < 0.001, correlation coefficient = -0.580). Intragastric volume 8 hours after a standard Asian meal intake was lower than 6 hours after a traditional Asian meal.

Effect of preoperative oral rehydration before cesarean section on ultrasound assessment of gastric volume and intraoperative hemodynamic changes: a randomized controlled trial

BackgroundCesarean section often requires an urgent transfusion load due to decreased blood pressure after spinal anesthesia. This prospective randomized study aimed to investigate whether a preoperative oral rehydration solution (ORS) stabilized perioperative circulatory dynamics.MethodsSixty-three parturients scheduled for cesarean section under combined spinal epidural anesthesia (CSEA) were randomly allocated to one of three groups: Group O received 500 mL ORS before bedtime and 500 mL 2 h before CSEA; Group M received mineral water instead of ORS; and Group C had no fluid intake (controls). After entering the operating room, stomach size was measured using ultrasound. Blood samples were obtained, and CSEA was induced. Vasopressors were administered when systolic blood pressure was < 90 mmHg or decreased by > 20%. As a vasopressor, phenylephrine (0.1 mg) was administered at ≥ 60 beats/min heart rate or ephedrine (5 mg) at < 60 beats/min heart rate. The primary outcome was the total number of vasopressor boluses administered. Secondary outcomes were the cross-sectional area of the stomach antrum, maternal plasma glucose levels, serum sodium levels, total intravenous fluid, bleeding volume, urine volume, operative time, and cord blood gas values after delivery.ResultsThe total number of vasopressor boluses was lower in Group O than in Group C (P < 0.05). Group O had lower total dose of phenylephrine than Group C (P < 0.05). There were no significant differences between Group M and other groups. No differences were detected regarding secondary outcomes.ConclusionsIn women scheduled for cesarean section, preoperative ORS stabilized perioperative circulatory dynamics. Neither ORS nor mineral water consumption increased the stomach content volume.Trial RegistrationThis trial is registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN000019825: Date of registration 17/11/2015).

Ultrasound Assessment of Gastric Volume in Parturients After High-Flow Nasal Oxygen Therapy.

High-flow nasal oxygen (HFNO) therapy is widely used in critical care obstetrics to improve oxygenation. Much of the benefit of HFNO is linked to the creation of modest levels of positive airway pressure. Pregnant women are generally considered to be at high risk of regurgitation and aspiration. It is unknown whether HFNO may cause gas insufflation into the stomach and further increase this risk. Therefore, this study aimed to systematically evaluate the possible safety effects of HFNO on gastric volume in healthy fasted parturients. Sixty fasted parturients scheduled for elective cesarean delivery were enrolled in an observer-blinded, prospective, interventional study. We used ultrasonography to assess changes of antral cross-sectional area (CSA) and gastric volume before and after a 20-minute treatment with HFNO at a rate of 50 L·min -1 . The primary outcome was the change in gastric volume from before to after HFNO therapy, and the secondary outcome was the distribution of antral grades. In semirecumbent right lateral position, the antral CSA at baseline and after treatment with HFNO was 3.81 (3.01-4.72) cm 2 and 3.79 (3.03-4.54) cm 2 , respectively. The estimated fluid volume at baseline and after treatment with HFNO was 38.51 (33.39-54.62) mL and 39.71 (32.00-52.82) mL, respectively. All participants had either a grade 0 or grade 1 antrum, and most of them had a grade 0 antrum. There was no significant difference in gastric volume and distribution of antral grades before and after HFNO therapy. Gastric air distension was not shown in any of the parturients either at baseline or after treatment with HFNO. Treatment with HFNO for 20 minutes at flow rates up to 50 L·min -1 did not increase gastric volume in term pregnant women breathing spontaneously when evaluated by gastric ultrasonography.

Comparison of Preoperative Assessment of Gastric Volume and pH in Patients Undergoing Elective Surgery with Prior Two Hour Fasting versus Overnight FastingA Randomised Clinical Trial

Introduction: Aspiration of gastric content is a known lifethreatening, yet preventable complication of anaesthesia. While mostly all elective procedures do follow the preoperative fasting protocols as recommended by American Society of Anaesthesia (ASA), there are many situations where the fasting guideline cannot be followed considering the emergency. In such cases, bedside ultrasound assessment of gastric volume can become an important tool to stratify aspiration related risk. Aim: To find out the actual trends of gastric volume and pH in patients with two hour fasting with a prokinetic drug versus overnight fasting who are undergoing elective procedures. Materials and Methods: This single centre, randomised clinical trial was conducted in the Department of Anaesthesia at Dr. Sampurnanand Medical College, Jodhpur, Rajasthan, India, between December 2020 and July 2021, among 50 patients of ASA grade I undergoing elective procedures under general anaesthesia. Participants were divided into two groups. Group A patients were advised overnight fasting while group B participants were advised two hour fasting for clear liquids followed by intravenous (i.v.) metoclopramide injection. Assessment of gastric volume and other gastric parameters were done using a portable ultrasound machine. The pH of gastric content was measured using pH strips. Gastric content was obtained using Ryle’s Tube placed in the patient, postinduction of anaesthesia. Collected data was statistically analysed using Unpaired t-test for all qualitative data. Results: Significant difference in the anteroposterior diameter (3.46±0.34 in group A versus 2.24±0.30 in group B), cranio-caudal diameter (4.77±0.51 in group A versus 3.71±0.36 in group B), antral curved surface area (9.90±0.77 in group A versus7.77±1.04 in group B) and gastric volume (127.48±13.09 in group A versus 104.65±15.43 in group B) and pH (2.08±0.28 in group A versus 2.80±0.41 in group B) was observed (p-value=0.0001). However, no significant difference in any gastric parameter, mentioned above, was noted before and after injecting intravenous metoclopramide. Conclusion: Bedside ultrasound assessment of gastric volume is an important toolfor aspiration risk stratification especially in emergency, non-fasting patients.

Preoperative bedside ultrasound assessment of gastric volume and evaluation of predisposing factors for delayed gastric emptying: a case-control observational study.

Perioperative pulmonary aspiration of gastric content is a serious complication. Fasting guidelines try to ensure an empty stomach before intervention. Certain medications or pathologies may cause delayed gastric emptying. Bedside ultrasonography is a useful tool when gastric content status is unclear or in emergency situations where fasting is not feasible. The aim of this prospective case-control observational study was to assess differences in gastric fluid volume between fasted patients with or without predisposing factors for delayed gastric emptying. Patients were preoperatively scanned. Antral cross-sectional area was measured by two tracing methods and total gastric clear fluid volumes were calculated. Data was recorded from September 2018 to March 2019 in a university hospital setting in Barcelona, Spain. Fifty-three patients were enrolled, 23 with delayed gastric emptying predisposing factors (DGEF) and 30 without non-DGEF. Ultrasound-estimated gastric clear fluid volume was 35.21 ± 32.69mL in the DGEF versus 53.50 ± 30.72mL in the non-DGEF group (p = 0.08). Average volume per unit of weight was 0.61 ± 0.46mL/kg. Only 1 patient in the DGEF group had a volume that posed a higher risk of aspiration (1.57mL/kg). Perfect correlation (R = 0.91; p < 0.01) and concordance (0.91; 95% CI 0.83; 0.95) was found between tracing methods. Minimal gastric content was observed in scheduled surgery in spite of predisposing factors for delayed gastric emptying. Ultrasound clear gastric volume estimation was useful to assess preoperative bedside gastric content.

Ultrasound assessment of gastric emptying after breakfast in healthy preschool children.

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. 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). 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. 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.

Ultrasound assessment of gastric volume in severely obese individuals: a validation study

BackgroundPoint-of-care gastric ultrasound is an emerging tool to assess gastric content and volume at the bedside. The examination includes both a qualitative and a quantitative component. The aim of this study was to evaluate the performance of an existing model for predicting gastric volume in severely obese subjects (BMI >35 kg m−2). MethodsThis observer-blinded experimental study compared the gastric volume predicted based on a sonographically measured cross-sectional area of the gastric antrum with the gastric volume measured by suctioning under gastroscopic guidance in a cohort of severely obese subjects. Volumes between 0 and 400 ml, in 100 ml increments, were studied. Allocation was randomized, and all study observations were blinded to group allocation. The correlation and the level of agreement between predicted and observed volumes were studied. ResultsData from 38 subjects suggested that the gastric volume predicted by sonographic assessment correlated strongly with that measured by gastric suctioning (concordance correlation coefficient of 0.82 and Pearson’s correlation coefficient of 0.86). In addition, Bland–Altman analysis suggested a high level of agreement between the calculated and suctioned volumes, with a mean difference of 35 ml, and 95% limits of agreement similar (within 30%) to those observed in the non-obese population. ConclusionsOur results suggest that the existing mathematical model to determine gastric fluid volume based on sonographic assessment performs well in severely obese individuals.

Ultrasound assessment of gastric volume in children after drinking carbohydrate-containing fluids

BackgroundGastric ultrasound is a valid tool for non-invasive assessment of the nature and volume of gastric contents in adults and children. Perioperative fasting guidelines recommend oral carbohydrates up to 2 h before elective surgery. We evaluated gastric volume in children using ultrasound before and after drinking carbohydrate fluids before surgery. MethodsPaediatric patients younger than 18 yr old undergoing elective surgery were enrolled. Initial ultrasound assessment of gastric volume was performed after fasting for 8 h. Two hours before surgery, patients were given carbohydrate drinks: 15 ml kg−1 for patients younger than 3 yr old and 10 ml kg−1 for those more than 3 yr old. Before induction of general anaesthesia, the gastric volume was reassessed. Parental satisfaction scores (0+totally satisfied, 10+totally dissatisfied) and complications were recorded. ResultsOf the 86 enrolled patients, 79 completed the study; three refused to ingest the requested volume, and surgery was delayed for more than 2 h in four patients. The mean (sd) of the initial and second ultrasound measurements were 2.09 (0.97) and 1.85 (0.94) cm2, respectively (P+0.01; mean difference 0.24 cm2, 95% confidence interval 0.06–0.43). The median (interquartile range) satisfaction score was 2.4 (0–6). Two instances of postoperative vomiting and one instance of postoperative nausea occurred. ConclusionsCarbohydrate fluids ingested 2 h before surgery reduced the gastric volume and did not cause serious complications in paediatric patients. Parents were satisfied with the preoperative carbohydrate drink. Children may benefit from drinking carbohydrate fluids up to 2 h before elective surgery. Clinical trial registrationcris.nih.go.kr (KCT0001546).

Ultrasound assessment of gastric volume in the fasted pediatric patient undergoing upper gastrointestinal endoscopy: development of a predictive model using endoscopically suctioned volumes.

Aspiration of gastric contents can be a serious anesthetic-related complication. Gastric antral sonography prior to anesthesia may have a role in identifying pediatric patients at risk of aspiration. We examined the relationship between sonographic antral area and endoscopically suctioned gastric volumes, and whether a 3-point qualitative grading system is applicable in pediatric patients. Fasted patients presenting to a pediatric hospital for upper gastrointestinal endoscopy were included in the study. Sonographic measurement of the antral cross-sectional area (CSA) in supine (supine CSA) and right lateral decubitus (RLD CSA) position was completed, and the antrum was designated as empty or nonempty. Gastric contents were endoscopically suctioned and measured. Multiple regression analysis was used to fit a mathematical model to estimate gastric volume. One hundred patients (aged 11-216months) were included. The gastric antrum was measured in 94% and 99% of patients in the supine and RLD positions, respectively. Gastric antral CSA correlated with total gastric volume in both supine (ρ=0.63) and RLD (ρ=0.67) positions. A mathematical model incorporating RLD CSA and age (R(2) =0.60) was determined as the best-fit model to predict gastric volumes. Increasing gastric antral grade (0-2) was associated with increasing gastric fluid volume. The results suggest that sonographic assessment of the gastric antrum provides useful information regarding gastric content (empty versus nonempty) and volume (ml·kg(-1) ) in pediatric patients. Results suggest that the three-point grading system may be a valuable tool to assess gastric 'fullness' based on a qualitative exam of the antrum.

Intra- and Interrater Reliability of Ultrasound Assessment of Gastric Volume

Gastric sonography can provide information about gastric content and volume that can help determine aspiration risk at the bedside. The primary objective of this study is to assess the intrarater and interrater reliability of a previously validated method of gastric volume assessment based on gastric antral area. The secondary objective is to evaluate the agreement between two different methods to measure gastric antral area. Three independent raters performed a standardized gastric ultrasound assessment in healthy subjects who had been randomly allocated to ingest a predetermined volume of clear fluid (apple juice) from 0 to 400 ml. Each rater measured the gastric antral area, using twice the two-diameter method and twice the free-tracing method. The rater order was allocated at random and raters were unaware of the volume ingested and of one-another's measurements. The Guidelines for Reporting Reliability and Agreement Studies were followed for conducting and reporting this study. Twenty-two volunteers were studied. Ultrasound assessment of antral cross-sectional area and volume was found to have "nearly perfect" intrarater and interrater reliability (correlation coefficient >0.8) with maximum differences within 13%. A Bland-Altman analysis suggests that the free-tracing method and the two-diameter method are essentially equivalent, within a clinically acceptable level of agreement. Ultrasound assessment of gastric volume by clinical anesthesiologists is highly reproducible with high intrarater and interrater reliability. The free-tracing method to measure antral cross-sectional area is equivalent to the two-diameter method.

Ultrasound assessment of gastric volume in critically ill patients

To assess the feasibility and validity of ultrasonographic measurement of gastric antral cross-sectional area (usCSA) in critically ill patients to predict gastric volume and the use of computed tomography (CT) as a reference to measure gastric volume. This single-center, prospective, cross-sectional study included 55 critically ill patients who had an abdominal CT scan. usCSA measurements were performed within the hour preceding the CT scan. Gastric volumes were measured on the CT scan using semiautomatic software. The feasibility rate, performing conditions (% "good" and "poor"), internal and external validity of antral usCSA measurements, performed by an ICU physician, were assessed to predict gastric volume. Antral usCSA measurements were feasible in 95% of cases and were positively correlated with gastric volume measured by the CT scan when performed in "good" conditions (65%) (r = 0.43). There was good reproducibility of measurements (intraclass correlation coefficient of 0.97, CI 95% 0.96-0.99) and there was clinically acceptable agreement between measurements performed by radiologists and intensivists (bias -0.12 cm(2)). The receiver operating characteristic curve identified a cutoff value of 3.6 cm(2) that discriminated an "at-risk stomach" (volume >0.8 mL/kg) at a sensitivity of 76% and a specificity of 78%. Ultrasonographic measurement of antral CSA is feasible and reliable in the majority of critically ill patients. This technique could be useful to manage critically ill patients at risk of aspiration or with enteral feeding.

Ultrasound Assessment of Gastric Volume

To the Editor Using ultrasound, Perlas et al.1 assessed the accuracy of a 3-point grading system (0, 1, 2) describing the appearance of the gastric antrum and its correlation with gastroscopically measured fluid volume. As grade 1 was associated with gastric volume >100 mL in 23% of subjects, while gastric fluid volume was >100 mL in 75% of subjects with a grade 2, the authors concluded that this 3-point qualitative grading system could serve as a screening tool to differentiate between low and high gastric fluid volume states. However, based on the results of studies conducted in animals suggesting a volume of 50 mL (or 0.8 mL/kg) as a critical volume for severe aspiration in humans,2 it may be that a threshold of 100 mL above which patients were considered at risk of aspiration was too high. The pathophysiology of aspiration during general anesthesia involves several risk factors, any of which can lead to gastric distension and/or coughing, factors that may cause episodes of gastroesophageal reflux. The combination of a gastric volume >0.8 mL/kg with such risk factors may be sufficient to cause significant aspiration with pulmonary damage.3,4 As previously described, the cutoff value of antral area of 340 mm2 could be useful for diagnosing “risk stomach” (defined by a fluid gastric volume >0.8 mL/kg or presence of solid particles) with a high degree of accuracy.5 Furthermore, this measurement is easy to perform and does not require changing the patient’s position from supine to lateral decubitus; this measurement may also be more accurate than the pure qualitative system, since antral area correlated with gastric fluid volume.5 Therefore, we regret that the authors did not also assess this semiquantitative approach that we previously described to discriminate “empty stomach” from “risk stomach.”

Validation of a Mathematical Model for Ultrasound Assessment of Gastric Volume by Gastroscopic Examination

Validation of a Mathematical Model for Ultrasound Assessment of Gastric Volume by Gastroscopic Examination

Validation of a Mathematical Model for Ultrasound Assessment of Gastric Volume by Gastroscopic Examination

Pulmonary aspiration of gastric contents is a serious perioperative complication. Previous models of ultrasound gastric volume assessment are preliminary and have not been validated by an external "gold standard." In the present study we propose a more accurate model based on prospective data obtained from 108 patients undergoing bedside gastric sonography and upper gastrointestinal endoscopy (UGE). Patients undergoing elective UGE were randomized to ingest one of 6 predetermined volumes of apple juice after an 8-hour fasting period. A cross-sectional area of the antrum in the right lateral decubitus position (Right lat CSA) was measured by a blinded sonographer following a standardized scanning protocol. Gastric fluid was subsequently suctioned under gastroscopic vision during UGE performed by a blinded gastroenterologist and measured to the nearest milliliter. Data from 108 patients suggest that a previously reported model tends to overestimate gastric volume particularly at low volume states. A new best fit mathematical model to predict gastric fluid volume based on measurements of Right lat CSA is presented. This new model built on a more accurate gold standard can be used to estimate gastric volumes from 0 to 500 mL, in nonpregnant adults with body mass index<40 kg/m2. We report a new prediction model to assess gastric fluid volume using standard 2-dimentional bedside ultrasound that has several advantages over previously reported models.