Measurement Of Antral Cross-sectional Area Research Articles

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

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

Gastric Residual Volume Assessment by Gastric Ultrasound in Fasting Obese Patients: A Comparative Study

BackgroundGastric ultrasound is an emerging tool for preoperative evaluation of gastric content and volume.ObjectivesTo assess gastric residual volume in normal-weight and obese patients scheduled for elective surgery.MethodsThis prospective observational study was conducted on 100 patients assigned to two groups of 50 patients each. The obese group included patients with body mass index (BMI) of 30 - 40 and American Society of Anesthesiologists (ASA) grade II and those with BMI > 40 and ASA III without other comorbidities; the normal-weight group included patients with normal BMI and ASA I. Gastric volume was predicted in each group using sonographic measurement of antral cross-sectional area (CSA) in semi-sitting and right lateral positions (RLP); the two groups were compared to assess the risk of aspiration for each group preoperatively.ResultsDespite intergroup differences in antral CSA, the sonographically predicted gastric volume was < 1.5 mL/kg in both groups in both positions. Both groups were at a low risk for aspiration, and 98% of the patients showed grade 0 or 1 in antrum assessments, corresponding to an empty antrum and minimal fluid only in the RLP, respectively. Only 2% of the patients in both groups showed a distended antrum in both positions.ConclusionsDespite the differences in CSA between obese and normal-weight participants in both positions (obese > normal-weight), both groups showed a low predicted gastric residual volume < 1.5 mL/kg and were at low risk for aspiration, provided that fasting was initiated at least 8 hours before elective surgery.

Value of ultrasonographic measurement of antral cross-sectional area in assessing preoperative gastric content volume in preschool pediatric patients

Objective To evaluate the value of ultrasonographic measurement of the antral cross-sectional area (CSA) in assessing the preoperative gastric content volume in preschool pediatric patients. Methods Fifty American Society of Anesthesiologists physical status Ⅰ or Ⅱ pediatric patients of both sexes, aged <7 yr, undergoing elective non-gastrointestinal surgery, were fasted according to the preoperative fasting guidelines recommended by American Society of Anesthesiologists.Sedation was performed with intravenously injected midazolam or with intravenously injected midazolam and propofol after admission to the operating room.The antral CSA in the supine and right lateral decubitus positions was measured using bedside ultrasonography and free tracing method.A gastric tube was inserted after gastric sonography to collect the gastric fluid, and the total volume of the gastric fluid was considered to be the gastric content volume. Results Six pediatric patients were excluded due to the unsatisfactory ultrasound image, and 44 pediatric patients were included.Gastric content volume and gastric content volume per kilogram of body weight were positively correlated with the antral CSA in the right lateral decubitus position, and the Spearman correlation coefficients were 0.48 (P 0.05). Conclusion Ultrasonographic measurement of the antral CSA in the right lateral decubitus position can be used to assess the preoperative gastric content volume in preschool pediatric patients. Key words: Ultrasonography; Child, preschool; Gastrointestinal contents

Optimal pressure for facemask ventilation during induction of general anesthesia in adult patients: real-time ultrasonographic measurement of antral cross-sectional area

Objective To determine the optimal pressure for facemask ventilation during induction of general anesthesia by real-time ultrasonographic measurement of antral cross-sectional area(CSA)in adult patients. Methods Sixty American Society of Anesthesiologists physical statusⅠor Ⅱ patients, aged 18-60 yr, with body mass index of 20-25 kg/m2, scheduled for elective operation under general anesthesia, were divided into 5 groups(n=12 each)using a random number table: P10 group, P13 group, P16 group, P19 group and P22 group.After induction of anesthesia, an oropharyngeal airway was inserted, and the patients were ventilated for a 2-min period in a pressure-controlled mode using the two-handed mask ventilation technique.The pressure for facemask ventilation was 10, 13, 16, 19 and 22 cmH2O in P10, P13, P16, P19 and P22 groups, respectively.The antral CSA was measured using real-time ultrasonography before and after facemask ventilation.Respiratory parameters were recorded. Results Compared with group P10, the number of patients in whom CSA<340 mm2 after facemask ventilation was significantly decreased in P16, P19 and P22 groups, and the number of patients in whom the tidal volume ≥ 6 ml/kg was increased in P13, P16, P19 and P22 groups(P< 0.01). The number of patients in whom optimal pressure for facemask ventilation was achieved was 2, 10, 6, 4 and 1 in P10, P13, P16, P19 and P22 groups, respectively, with the most cases in group P13(P < 0.01). Conclusion The optimal pressure is 13 cmH2O for facemask ventilation during induction of general anesthesia when determined by real-time ultrasonographic measurement of antral CSA, and it can ensure adequate oxygen supply and reduce gastric insufflation in adult patients. Key words: Masks; Ultrasonography; Respiration, artificial

Ultrasonographic Evaluation of Gastric Content During Labour Under Epidural Analgesia

Background Women in labour are considered at risk of gastric content aspiration partly because the stomach remains full before delivery. Ultrasonographic measurement of antral cross-sectional area (CSA) is a validated method of gastric content assessment. Our aim was to determine gastric content volume and its changes in parturients during labour under epidural analgesia using bedside ultrasonography. Methods The cut-off value corresponding to an increased gastric content was determined by ultrasound measurement of antral CSA in six pregnant women in late pregnancy before and after ingestion of 250 ml of non-clear liquid. Antral CSA was then measured twice in 60 parturients who presented in spontaneous labour: when the anaesthesiologist was called for epidural analgesia catheter placement, and at full cervical dilatation. Patient-controlled epidural analgesia was performed with a solution of ropivacaine and sufentanil. Results After liquid ingestion, antral CSA (mm 2 ) increased from 90 (range, 80–151) to 409 (range, 317–463). A CSA of 320 was taken as cut-off value. The feasibility rate of antral CSA determination was 96%. CSA decreased from 319 [Q1 158–Q3 469] to 203 [Q1 123–Q3 261] during labour ( P =2×10 −7 ). CSA was >320 in 50% of parturients at the beginning of labour vs 13% at full cervical dilatation ( P =0.006). Conclusions Bedside ultrasonographic antral CSA measurement is feasible in pregnant women during labour and easy to perform. The observed decrease in antral CSA during labour suggests that gastric motility is preserved under epidural anaesthesia. The procedure could be used to assess individual risk of gastric content aspiration during labour.

Ultrasonographic evaluation of gastric content during labour under epidural analgesia: a prospective cohort study

Women in labour are considered at risk of gastric content aspiration partly because the stomach remains full before delivery. Ultrasonographic measurement of antral cross-sectional area (CSA) is a validated method of gastric content assessment. Our aim was to determine gastric content volume and its changes in parturients during labour under epidural analgesia using bedside ultrasonography. The cut-off value corresponding to an increased gastric content was determined by ultrasound measurement of antral CSA in six pregnant women in late pregnancy before and after ingestion of 250 ml of non-clear liquid. Antral CSA was then measured twice in 60 parturients who presented in spontaneous labour: when the anaesthesiologist was called for epidural analgesia catheter placement, and at full cervical dilatation. Patient-controlled epidural analgesia was performed with a solution of ropivacaine and sufentanil. After liquid ingestion, antral CSA (mm(2)) increased from 90 (range, 80-151) to 409 (range, 317-463). A CSA of 320 was taken as cut-off value. The feasibility rate of antral CSA determination was 96%. CSA decreased from 319 [Q1 158-Q3 469] to 203 [Q1 123-Q3 261] during labour (P=2×10(-7)). CSA was >320 in 50% of parturients at the beginning of labour vs 13% at full cervical dilatation (P=0.006). Bedside ultrasonographic antral CSA measurement is feasible in pregnant women during labour and easy to perform. The observed decrease in antral CSA during labour suggests that gastric motility is preserved under epidural anaesthesia. The procedure could be used to assess individual risk of gastric content aspiration during labour.

THIS MONTH IN Anesthesiology

The incidence, risk factors, sequelae, and prevention of intraoperative awareness are reviewed.Children undergoing inguinal hernia repair had normal academic performance at age 15–16.An oxygenated polyethylene glycol–modified hemoglobin was evaluated in patients undergoing total hip replacement. See the accompanying Editorial View on page 1016 In piglets, the benefits of a vital capacity maneuver followed by one-lung ventilation with reduced tidal volume were studied. See the accompanying Editorial View on page 1009 This clinical scenario discusses the key issues of perioperative bronchospasm.Pulmonary aspiration of gastric contents is a common complication of anesthesia and cause of morbidity and mortality. To determine if ultrasonographic measurement of antral cross-sectional area (CSA), a noninvasive test of gastric content volume, may help to reduce this complication, a prospective observational study was conducted in 180 patients. There was a positive correlation between antral CSA and aspirated gastric fluid volume. Assessment of a “risk stomach” was made using a CSA cutoff value of 340 mm2; this was associated with sensitivity of 91% and a specificity of 71% for “risk stomach.” Use of antral CSA may help to reduce pulmonary aspiration of gastric contents during general anesthesia.Mechanical lung ventilation may lead to lung injury via pulmonary inflammation. These investigators evaluated the utility of measuring exhaled breath condensates (EBCs) as a measure of lung inflammation and injury in ventilated patients. EBC pH and inflammatory markers were measured in mechanically ventilated patients without acute lung injury or sepsis (n = 27). Compared with healthy controls, EBC pH was lower whereas inflammatory markers (e.g., interleukin [IL]-1β, tumor necrosis factor-α, IL-6, IL-10, IL-12p70) were higher in ventilated patients. No difference was observed between patients who received either zero end-expiratory pressure or positive end-expiratory pressure. This study demonstrated the presence of inflammatory markers in patients with mechanical lung ventilation in the absence of acute lung injury or sepsis, which is unaffected by expiratory pressure induced. A relation to systemic inflammatory markers was also present.The potential protective effects of lower tidal volumes (TV) in patients without lung injury undergoing elective surgery are not known. In a single-center randomized controlled trial, patients (N = 149) received either 6 ml/kg TV ventilation or 10 ml/kg TV while undergoing elective cardiac surgery. Median ventilation times, intensive care unit length of stay, and hospital length of stay were similar between groups. However, in the lower TV group, a higher proportion of patients were ventilation free at 6 h and fewer patients required reintubation compared with the higher TV group. Lower TV did not provide additional benefit in terms of time to extubation for patients undergoing elective surgery. See the accompanying Editorial View on page 1011

Clinical Assessment of the Ultrasonographic Measurement of Antral Area for Estimating Preoperative Gastric Content and Volume

This prospective observational study aimed to assess the feasibility and performance of the ultrasonographic measurement of antral cross-sectional area (CSA) for the preoperative assessment of gastric contents and volume in adult patients and for the diagnosis of risk stomach (defined by the presence of solid particles and/or gastric fluid volume >0.8 ml/kg). A preoperative ultrasonographic measurement of the antral CSA was performed for each patient by a physician (L.B.) blinded to the history of the patient. Immediately after tracheal intubation, an 18-French multiorifice Salem tube was inserted and gastric contents were aspirated in five different patient positions; during this time, the patient's epigastrium was massaged and the tube was moved backward and forward in the stomach. The relationship between the antral area and the volume of aspirated gastric contents was analyzed, as was the performance of ultrasonographic measurement of antral area for the diagnosis of risk stomach. The measurement of antral CSA was performed on 180 of 183 patients. A significant positive relationship between antral CSA and aspirated fluid volume was found. The cutoff value of antral CSA of 340 mm(2) for the diagnosis of risk stomach was associated with a sensitivity of 91% and a specificity of 71%. The area under the receiver operating characteristic curve for the diagnosis of risk stomach was 90%. The ultrasonographic measurement of antral CSA could be an important help for the anesthesiologist in minimizing the risk of pulmonary aspiration of gastric contents due to general anesthesia.

Could a single standardized ultrasonographic measurement of antral area be of interest for assessing gastric contents? A preliminary report

The aim of this preliminary study performed on volunteers was to assess whether a standardized ultrasonographic measurement of the gastric antral cross-sectional area in a single section of the stomach could discriminate between gastric contents after 12 h fasting (fasting stomach) and gastric contents 2 h after ingestion of nonclear liquids or a solid meal. In this crossover study, ultrasonographic measurements of the antral area were performed in the morning in healthy volunteers in three situations in randomized order: after 12 h fasting, 2 h after a solid meal of 300 kcal and 2 h after ingestion of 200 ml of nonclear liquids. These measurements were performed by a physician blinded to the volunteers' status, according to a standardized method, using the abdominal aorta and the left lobe of the liver as internal landmarks. Antral areas were compared among the three sessions, and performance of the test was assessed by plotting receiver operating characteristic curves and calculating the area under the receiver operating characteristic curves for the diagnosis of fasting gastric contents. Twenty-two volunteers were included, and 65 measures were performed. Antral area was significantly smaller in fasting than in postprandial sessions. The receiver operating characteristic curves showed an excellent performance of ultrasonographic measurement of antral area for discriminating gastric contents in fasting session from gastric contents in nonfasting sessions. Results of this preliminary study should be corroborated in further trials. However, one can suppose that ultrasonographic measurement of the antral cross-section area could be of interest for the diagnosis of preoperative gastric vacuity.

Simultaneous measurement of gastric emptying of a solid meal by ultrasound and by scintigraphy

OBJECTIVE: Although ultrasonic imaging may represent a valid alternative to scintigraphy for measurement of gastric emptying, most studies comparing the two methods have been carried out with liquid meals. The aim of this study was to compare scintigraphic and ultrasonographic measurements of gastric emptying of a solid meal in healthy subjects and in patients with possible delay in emptying. METHODS: Nineteen subjects were studied: five controls, six patients with gastroesophageal reflux, and eight patients with dysmotility-like dyspepsia. Gastric emptying was measured by both scintigraphy and ultrasonography after ingestion of an 800-calorie solid, realistic meal containing 99mTc-labeled chicken liver. Scintigraphic measurements were made every 15 min for 6 h, and ultrasonic imaging of antral sections was undertaken every 15 min for the first 1 h and every 30 min thereafter. Total emptying times were calculated independently using the two methods, and the emptying patterns recorded by the two methods were compared. RESULTS: Maximal antral dilation occurred 30 min (range 0–90 min) after the end of the meal and persisted until 96 ± 42 min, by which time gastric radioactivity had decreased from its maximum by 43% ± 23%. From this time on, the antral cross-sectional area returned toward the basal value, declining faster than the gastric counts recorded by scintigraphy. Total emptying times measured by ultrasound and by scintigraphy were in good agreement in all subjects, with a mean difference of only 4.5 min (limits of agreement, −17.1 to 21.6 min). CONCLUSIONS: Ultrasonographic measurement of antral cross-sectional area provides a valid alternative to scintigraphy for the measurement of total gastric emptying of a solid meal. It is less reliable if other parameters of gastric emptying such as T 1/2 are required.

Gastric emptying and gastro-oesophageal reflux in preterm infants.

Gastro-oesophageal reflux is common in preterm infants, but the role of gastric emptying as a causal factor has not been studied before. Gastric emptying was therefore measured in 19 healthy preterm infants (median gestational age 32 weeks) while concurrently measuring 24 hour lower oesophageal pH, using an antimony pH electrode, positioned manometrically. Real time ultrasonic images of the gastric antrum were obtained, and measurements of antral cross-sectional area (ACSA) were made immediately before a nasogastric feed and then during subsequent gastric emptying until ACSA returned to its pre-feed value. Half emptying time (50% delta ACSA) was calculated as the time taken for the ACSA to fall to half the maximal postprandial increment. Mean (SEM) reflux index for the group was 11.9 (2.0)%; number of reflux episodes per 24 hours: 15.4 (1.7); and number of reflux episodes longer than five minutes 5.5 (0.8). Average half emptying times for an individual infant were: median (range) 46 (18-105) minutes. There was no association between gastric emptying rates and any of the indices of gastro-oesophageal reflux, either during the entire 24 hour period for which the lower oesophageal pH was recorded, or in the postprandial periods after the feeds which were studied ultrasonically. Gastro-oesophageal reflux was also unrelated to feed volume and feed type. Asymptomatic gastro-oesophageal reflux is common in preterm infants, but gastric emptying time is not a determinant of it. Inappropriate relaxation of the lower oesophageal sphincter or abnormal oesophageal motility offer more plausible explanations.