Interrater reliability of qualitative ultrasound assessment of gastric content in the third trimester of pregnancy

Diagnostic accuracy of a simple qualitative ultrasound assessment for the diagnosis of high-risk gastric contents in the parturient. A prospective observational cohort study

STUDY OBJECTIVE

Interpretation of gastric ultrasound relies on the use of a clinical algorithm that combines qualitative analysis of the gastric antrum contents with the calculation of the volume of fluid contents. This reference method may be difficult to apply in the parturient. We therefore aimed to assess the diagnostic accuracy of a simple qualitative assessment in the supine position for the diagnosis of high-risk gastric contents in the parturient. We also assessed the diagnostic accuracy of a composite scale and another clinical algorithm based on a mathematical model different to that used in the reference method.

DESIGN

Prospective observational cohort study.

SETTING

University hospital, Lyon, France.

PATIENTS

Adult women admitted to the delivery room.

INTERVENTIONS

Qualitative and quantitative gastric ultrasound examination within the first hour following admission.

MEASUREMENTS

With respect to the reference method, the diagnostic accuracy of a simple qualitative assessment for the diagnosis of high-risk gastric contents was assessed. The diagnostic accuracy of a composite scale and another clinical algorithm, and the agreement between each approach were also assessed.

MAIN RESULTS

A total of 235 parturients were included and analyzed. The simple qualitative assessment led to conclusive ultrasound assessment in 233 (99%) women, while the reference method led to conclusive assessment in 213 (91%) women (P < 0.05). The sensitivity and the specificity of the simple qualitative assessment were 97% (95%CI: 93 to 99%) and 96% (95%CI: 90 to 99%), respectively. These were not significantly different from those of the composite scale and the clinical algorithm. The four approaches showed almost perfect agreement with each other.

CONCLUSIONS

These results suggest that simple qualitative assessment may be useful in clinical practice to help the anesthesiologist in the assessment of gastric contents status and risk of aspiration.

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

Prevalence and factors associated with high-risk gastric contents in women admitted to the maternity unit for childbirth: a prospective multicentre cohort study

BACKGROUND

This multicentre prospective observational study sought to determine the prevalence and the factors associated with high-risk gastric contents in women admitted to the maternity unit for childbirth, and to identify the clinical situations in which ultrasound assessment of gastric contents would be most helpful (i.e. when the prevalence of high-risk gastric contents is close to 50%).

METHODS

Ultrasound assessments of gastric contents were performed within the first hour after admission to the maternity unit. The prevalence of high-risk gastric contents was calculated and variables associated with high-risk gastric contents were identified using logistic regression analyses.

RESULTS

A total of 1003 parturients were analysed. The prevalence of high-risk gastric contents was 70% (379/544; 95% confidence interval: 66-74%) in women admitted in spontaneous labour and 65% (646/1003; 95% confidence interval: 61-67%) in the whole cohort. Lower gestational age, increased fasting duration for solids, and elective Caesarean delivery were independently associated with reduced likelihood of high-risk gastric contents. In women admitted in spontaneous labour and in the whole cohort, the prevalence of high-risk gastric contents ranged from 85% to 86% for fasting duration for solids <6 h, 63%-68% for fasting 6-8 h, 54%-55% for fasting 8-12 h, and 47%-51% for fasting ≥12 h.

CONCLUSIONS

Around two-thirds of parturients had high-risk gastric contents within the first hour after admission to the maternity unit. Our results suggest that gastric emptying for solids continues in labouring women, and that gastric ultrasound would be most helpful when fasting duration is ≥8 h.

Diagnostic accuracy of a simple qualitative ultrasound assessment for the diagnosis of empty stomach in the adult: A supplementary analysis of a prospective observer-blind randomized crossover study

BACKGROUND

It has been reported that qualitative ultrasound assessment performed in the semi-upright position had high sensitivity to detect gastric fluid volume >1.5 mL.kg-1 . Nevertheless, the diagnostic accuracy of qualitative assessment for the diagnosis of empty stomach (fluid volume <0.8 mL.kg-1 ) has not been assessed. We aimed to assess the diagnostic accuracy of simple qualitative ultrasound assessment with and without head-of-bed elevation to 45° for the diagnosis of an empty stomach. We also aimed to determine the diagnostic accuracy of a composite ultrasound scale and clinical algorithm.

METHODS

We performed a supplementary analysis of a prospective observer-blind randomized crossover trial in which adult fasting volunteers attended two distinct sessions, with the head-of-bed angled either at 0° or 45°, in a randomized order. Three tests were performed within each session, each corresponding to a different (either 0, 50, 100, 150 or 200 mL) and randomized volume of water; the same volumes were ingested in both sessions, in a randomized order. Ultrasounds were performed 3 min after water ingestion, blindly to the volume ingested.

RESULTS

We included 20 volunteers in whom 120 measurements were analyzed. The sensitivity and specificity of the qualitative assessment in the semirecumbent position were 93% (95% CI: 68-100) and 89% (95% CI: 76-96), respectively. The composite scale and clinical algorithm did not have better diagnostic accuracy than the qualitative assessment performed with head-of-bed elevation. Without head-of-bed elevation, the clinical algorithm had significantly higher specificity (98% [95% CI: 88-100]) than qualitative assessment (67% [95% CI: 51-80]; p < 0.05).

CONCLUSION

These results suggest that qualitative assessment in the semirecumbent position had high diagnostic accuracy for the diagnosis of fluid volume <0.8 mL.kg-1 ; this method can be used in clinical practice for reliable diagnosis of empty stomach.

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

BACKGROUND

Cesarean 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.

METHODS

Sixty-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.

RESULTS

The 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.

CONCLUSIONS

In women scheduled for cesarean section, preoperative ORS stabilized perioperative circulatory dynamics. Neither ORS nor mineral water consumption increased the stomach content volume.

TRIAL REGISTRATION

This trial is registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN000019825: Date of registration 17/11/2015).

Gastric Emptying Velocity After Labor Analgesia Assessed by Sonography: A Prospective Controlled Observational Study

Objective

The effect of labor analgesia on gastric emptying rate will affect the management of fasting during the perinatal period. To evaluate gastric emptying after labor analgesia using the gastric antrum ultrasound examination.

Methods

From September 2022 to January 2023, a prospective controlled observational study was conducted. The Study group (epidural analgesia group) and Observation group (pharmacological and non-pharmacological interventions group) were successively enrolled and grouped using the random envelope method. However, labor analgesia was supplied according to maternal women's wishes, and intention-to-treat (ITT) and per-protocol (PP) analyses were performed to establish its effect on stomach emptying. The gastric emptying rate during the first stage of labor was considered to be the primary outcome.

Results

From September 2022 to January 2023, 120 persons were studied, 90 in the Study group and 30 in the Observation group. 33 people's analgesic selection was discordant with the grouped one. ITT analysis showed that the Study group's cross-sectional area (CSA) fell from baseline (624.19 ± 92.70 mm²) to 334.64 ± 46.32 mm² after 1 hour and to 217.26 ± 29.90 mm² after 2 hours. In the Observation group, the CSA similarly dropped from 620.10 ± 100.73 mm² to 331.30 ± 51.19 mm² and 214.70 ± 28.73 mm², p<0.001. CSA was not significantly different between groups, p>0.05. The PP analysis also indicated no significant changes in the CSA between the two groups at 3 time-points, p>0.05. At the first hour, the Study and Observation group had stomach emptying speeds of 300.05 ± 103.74 mm²/h and 259.50 ± 125.25 mm²/h, respectively, which were greater than those at the second hour (115.75 ± 43.51 mm²/h vs 124.36 ± 58.98 mm²/h), p<0.001.

Conclusion

Epidural analgesia, pharmacological, and non-pharmacological labor analgesia had little effect on gastric emptying, and gastric antrum ultrasonography can be utilized to monitor maternal gastric volume changes.

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.

Diagnostic performance of qualitative ultrasound assessment for the interpretation of point-of-care gastric ultrasound to detect high gastric fluid volume: A prospective randomized crossover study

STUDY OBJECTIVE

This study aimed to assess whether elevating the head of the bed to 45° was associated with sensitivity >90% of the qualitative ultrasound assessment for the diagnosis of gastric fluid volume > 1.5 ml.kg^-1. We also assessed the performance of qualitative assessment, composite ultrasound scale, and clinical algorithm, for the diagnosis of fluid volume > 1.5 ml.kg^-1 according to whether the head of the bed was elevated to 45° or not.

DESIGN

Prospective randomized observer-blind crossover trial.

SETTING

Hospices Civils de Lyon, France.

PATIENT

Healthy adult volunteers.

INTERVENTIONS

Two separate study sessions in fasting volunteers: with and without head-of-bed elevation to 45°, in a randomized order. Each session consisted of three tests, each corresponding to a randomized and different volume of water (either 0, 50, 100, 150 or 200 ml); the same volumes were used in both sessions and in a randomized order. Gastric ultrasounds were performed three minutes after the ingestion of water by an investigator blinded to the volume ingested.

MEASUREMENTS

Diagnostic performance of each approach for the diagnosis of gastric fluid volume > 1.5 ml.kg^-1.

MAIN RESULTS

Twenty volunteers were included, and 120 measurements were analyzed. The sensitivity of the qualitative assessment for the diagnosis of gastric fluid volume > 1.5 ml.kg^-1 with and without head-of-bed elevation was 91% (95%CI: 75-98) and 75% (95%CI: 57-89), respectively. The clinical algorithm with head-of-bed elevation had significantly better sensitivity than the qualitative assessment with no head-of-bed elevation; there was no significant difference for other comparisons.

CONCLUSIONS

The results suggest that qualitative examination of gastric antrum in the supine position with head-of-bed elevation to 45° can discriminate between low and high gastric fluid volume with high sensitivity, while neither the composite ultrasound scale nor the clinical algorithm improved the diagnostic performance of gastric ultrasound for the diagnosis of gastric fluid volume > 1.5 ml.kg^-1.

Prevalence of risk stomach in laboring women allowed to unrestrictive oral intake: a comparative cross-sectional study

Background

Although restricting food intake during labor is recommended by guidelines, intrapartum starvation has not been popular in some regions. We conducted this comparative cross-sectional study to determine the prevalence of risk stomach in non-fasted laboring women compared with fasted non-laboring women using gastric ultrasound.

Methods

Ultrasound examination of the antrum was performed in 50 term fasted non-laboring women before elective cesarean delivery and 50 laboring women allowed to eat and drink during active labor. Examinations consisted of the qualitative (antral grades, 0–3) and quantitative evaluation (antral cross-sectional area and calculated gastric volume) in the supine and right lateral decubitus (RLD) position. A risk stomach was defined as an antral grade ≥ 2 or grade 1 with gastric volume ≥ 1.5 ml· kg^− 1.

Results

No non-laboring women had grade ≥ 2, while 34 (68%) laboring women had grade ≥ 2. Nine (18%) non-laboring and 40 (80%) laboring women presented risk stomach (P < 0.001) (risk ratio: 4.4, 95% CI 2.4–8.2). Compared with non-laboring women, laboring women had larger antral area at “empty” stomach (grade 0) (437 mm² vs.350 mm² in supine, 571 mm² vs.480 mm² in RLD, P < 0.05) and cut-off values of antral area to discriminate a risk stomach (510 mm² vs. 453 mm² in supine, 670 mm² vs. 605 mm² in RLD).

Conclusions

This study confirms a higher prevalence of risk stomach presents in laboring women under a liberal eating policy, gastric ultrasound is therefore useful for this risk population if general anesthesia is required unexpectedly.

Pregnancy and Labor Epidural Effects on Gastric Emptying: A Prospective Comparative Study

BACKGROUND

The lack of reliable data on gastric emptying of solid food during labor has led to some discrepancies between current guidelines regarding fasting for solid food in the parturient. This prospective comparative study aimed to test the hypothesis that the gastric emptying rate of a light meal would be reduced in parturients receiving epidural analgesia and with no labor analgesia compared with nonpregnant and pregnant women.

METHODS

Ten subjects were enrolled and tested in each group: nonpregnant women, term pregnant women, parturients with no labor analgesia, and parturients with epidural labor analgesia. After a first ultrasound examination was performed to ensure an empty stomach, each subject ingested a light meal (125 g yogurt; 120 kcal) within 5 min. Then ultrasound measurements of the antral area were performed at 15, 60, 90, and 120 min. The rate of gastric emptying at 90 min was calculated as [(antral area90 min / antral area15 min) - 1] × 100, and half-time to gastric emptying was also determined. For the Parturient-Epidural group, the test meal was ingested within the first hour after the induction of epidural analgesia.

RESULTS

The median (interquartile range) rate of gastric emptying at 90 min was 52% (46 to 61), 45% (31 to 56), 7% (5 to 10), and 31% (17 to 39) for nonpregnant women, pregnant women, parturients without labor analgesia, and parturients with labor epidural analgesia, respectively (P < 0.0001). The rate of gastric emptying at 90 min was statistically significant and lower in the Parturient-Epidural group than in the Nonpregnant and Pregnant Control groups. In addition, the rate of gastric emptying at 90 min was statistically significant and lower in the Parturient-No-Epidural group than in the Parturient-Epidural group.

CONCLUSIONS

Gastric emptying in parturients after a light meal was delayed, and labor epidural analgesia seems not to worsen but facilitates gastric emptying. This should be taken into consideration when allowing women in labor to consume a light meal.

EDITOR’S PERSPECTIVE

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.

Point of Care Ultrasound on Labor and Delivery

Point of care ultrasound (POCUS) in the field of obstetric anesthesiology, including cardiac, pulmonary, neuraxial, gastric, and airway ultrasound, can facilitate rapid diagnosis, management, and clinical decision-making surrounding common maternal peripartum comorbidities, and obstetric complications. Routine and proficient utilization of POCUS can ultimately aid in anesthesiologists' role as critical care physicians in the multidisciplinary practice on labor and delivery, with potential future research aiming to determine the potential impact on maternal morbidity and mortality.

Gastric point-of-care ultrasound (PoCUS) during pregnancy and the postpartum period: a systematic review

Personalised risk assessment of the likelihood of pulmonary aspiration is recommended for pregnant women undergoing general anaesthesia and gastric point-of-care ultrasound (PoCUS) may help to achieve this. Traditionally, risk assessment is based upon adherence to fasting times, but gastric emptying may vary during pregnancy and surgery often needs to be expedited. We systematically reviewed the evidence for gastric PoCUS up to August 2018 in pregnant and postpartum women to determine whether it can identify and quantify stomach contents, provide aspiration risk assessment via qualitative or quantitative means, and determine how gastric emptying is affected by pregnancy. Twenty-two articles comprising 1050 participants were included and studies were classified by qualitative or quantitative findings. The evidence suggests that gastric PoCUS is a reliable and feasible method of imaging the stomach in pregnancy in clinical practice. Qualitative assessment via the Perlas grading system can provide rapid assessment of gastric volume states. If fluid is visible, identification of patients at high risk of pulmonary aspiration requires measurement of antral cross-sectional area. Cut-off values of 608 mm² and 960 mm² are recommended in the semi-recumbent and right lateral semi-recumbent positions, respectively. Validated methods to quantify stomach volumes are available, however their usefulness is currently restricted to research. Gastric PoCUS also provides evidence that gastric emptying of ingested food is delayed by term pregnancy, labour and during the early postpartum period. However, the passage of fluids through the stomach appears unaffected throughout the peripartum period.

Ultrasound to guide the individual medical decision by evaluating the gastric contents and risk of aspiration: A literature review

Pulmonary aspiration of gastric contents is one of the most terrible complications following general anesthesia. It is important for patients to prevent this complication by obeying the preoperative fasting protocol strictly. At present, it has been reported by many studies that bedside ultrasound, as a non-invasive and convenient method, could be used to evaluate gastric contents qualitatively and quantitatively. With the advantages of reliability, accuracy and repeatability, it can greatly reduce the risk of aspiration and ensure patients' life security. But most of the data were acquired from the healthy volunteers. For the gastrointestinal disorder, the pregnant women, obesity, children, the elderly and diabetes patients, the accuracy and reliability of ultrasound to predict the risk of aspiration remains to be identified by more further studies. For these patients with increasing risk of aspiration, I-AIM (Indication, Acquisition, Interpretation, Medical decision-making) framework plays an important role in ensuring the safety of patients. It is crucial to make appropriate clinical decisions by evaluating the gastric contents with ultrasound.

Interpretation Accuracy and Interrater Agreement of Pediatric Skin and Soft Tissue Point-of-Care Ultrasound Images among Residents and Faculty

BACKGROUND

Point-of-care ultrasound (POCUS) is commonly used to facilitate care in the emergency department. Acquired images are often reviewed by local experts for educational and quality assurance purposes. However, no published study has examined the accuracy and reliability of POCUS image interpretation by multiple reviewers.

OBJECTIVES

We studied the accuracy and interrater agreement among expert and trainee reviewers of prerecorded pediatric skin and soft tissue (SST) POCUS images.

METHODS

POCUS faculty and emergency medicine (EM) residents blindly reviewed deidentified pediatric SST POCUS images and indicated whether a drainable fluid collection was present, absent, or indeterminate. This was then compared with the gold standard based on discharge diagnoses and telephone follow-up. Images rated as indeterminate were excluded from the initial analysis. Sensitivity analysis assuming indeterminate answers were inaccurate was subsequently conducted.

RESULTS

In phase 1, 6 pediatric EM POCUS directors reviewed 168 images. The overall accuracy was 79.7% (range 66.1-86.0%). The mean Cohen's kappa was 0.58 (range 0.24-0.84). Sensitivity analysis yielded an overall accuracy of 71.3% (range 56.5-76.9%) and a Cohen's kappa of 0.43 (range 0.20-0.59). In phase 2, 6 general EM POCUS faculty and 20 EM residents reviewed 120 images. The overall accuracy among residents was 72.2% (range 51.4-84.7%) and among faculty was 83.6% (range 77.9-88.8%). Sensitivity analysis yielded an overall resident accuracy of 63.0% (range 49.5-80.7) and an overall faculty accuracy of 73.9% (range 67.0-79.8%). Fleiss' kappa was 0.322 for residents and 0.461 for faculty.

CONCLUSIONS

We found moderate accuracy and fair to good interrater agreement among POCUS faculty and EM residents reviewing pediatric SST POCUS images.

Term pregnant patients have similar gastric volume to non-pregnant females: a single-centre cohort study

BACKGROUND

The physiological changes of pregnancy can increase the risk of peri-partum pulmonary aspiration. There is limited objective information regarding gastric volumes in pregnant patients. The aim of this cohort study was to characterise prospectively the range of gastric-fluid volume in term non-labouring pregnant patients compared with a historical cohort of non-pregnant females.

METHODS

Fasted non-labouring term pregnant patients scheduled for elective Caesarean delivery underwent a standardised gastric ultrasound examination. Gastric content was evaluated qualitatively (type of content), semi-quantitatively (Perlas grades), and quantitatively (volume). The antral cross-sectional area and volume were compared with those of a retrospective cohort of non-pregnant females from the same institution. Descriptive statistics were used to describe the central tendency through mean and median values. Dispersion was evaluated with standard deviation and inter-quartile range, and the higher end of the distribution as 95th percentile.

RESULTS

Non-labouring pregnant (59) and non-pregnant (81) subjects were studied. The range of estimated total gastric-fluid volume (P=0.96) and volume per body weight (P=0.78) was not significantly different between cohorts. An estimated volume of 115 ml (102-143) vs 136 ml (106-149) and volume per body weight of 1.4 ml kg^-1 (1.2-2.8) vs 2.0 ml kg^-1 (1.5-2.7) corresponded to the 95th percentile (95% confidence interval) values in the pregnant and non-pregnant cohort, respectively.

CONCLUSIONS

Baseline gastric volume of non-labouring pregnant patients at term is not significantly different from that of non-pregnant females. This information will be helpful to interpreting findings of gastric point-of-care ultrasound in obstetric patients.

Ultrasound assessment of the gastric contents for the guidance of the anaesthetic strategy in infants with hypertrophic pyloric stenosis: a prospective cohort study

BACKGROUND

Evacuation of gastric content through a nasogastric tube, followed by rapid sequence induction, is usually recommended in infants undergoing pyloromyotomy. However, rapid sequence induction may be challenging, and is therefore controversial. Some anaesthetists regularly perform classical non-rapid induction technique, after blind aspiration of the gastric contents, although this aspiration may have been incomplete. This prospective observational study aimed to assess whether the ultrasound monitoring of the aspiration of the stomach contents, may be useful to appropriately guide the choice of the anaesthetic induction technique, in infants undergoing pyloromyotomy.

METHODS

Infants undergoing pyloromyotomy were consecutively included. Ultrasound assessment of the antrum was performed before and after the aspiration of the gastric contents through a 10 French gastric tube. The stomach was defined as empty when no content was seen in both supine and right lateral positions. The correlation between antral area and the aspirated gastric volume was also tested.

RESULTS

We analysed 34 infants. Ultrasound examination of the antrum failed in three infants. The stomach was empty in 30/34 infants (nine before aspiration, 21 after aspiration), allowing to perform a non-rapid induction technique in 88.2% of the infants. There was a significant correlation between antral area measured in right lateral decubitus and the aspirated gastric volume.

CONCLUSIONS

Our results suggest that the qualitative ultrasound assessment of the antral content may be a simple and useful point-of-care tool, for the choice of the most appropriate anaesthetic technique for pyloromyotomy according to the estimated risk of pulmonary aspiration of gastric contents.

Ultrasound assessment of gastric content in the immediate postpartum period: a prospective observational descriptive study

INTRODUCTION

Pulmonary aspiration of gastric contents in pregnant women undergoing general anesthesia or sedation/analgesia in the peripartum period is a feared complication in obstetric anesthesia. We assessed the changes in antral cross-sectional area (CSA) with ultrasonography in laboring women and in the immediate postpartum period.

PATIENTS AND METHODS

In an observational study in a university-affiliated maternity, gastric ultrasonography examinations were performed in non-consecutive laboring women, after epidural analgesia insertion and after childbirth. Assessment of antral CSA, difficulty of performance on a numerical scale, and factors that could influence gastric content were noted. A cut-off value of 381 mm² was taken for the diagnosis of empty stomach.

RESULTS

One hundred women were enrolled in the study. Median antral CSA was 469 mm² [25th-75th] [324-591] after epidural insertion and 427 mm² [316-574] after delivery. Antral CSA was ≥ 381 mm² in 59 of 90 women (65%) after epidural insertion vs. 48 of 100 women (48%) after delivery (P = 0.59). Median variation of antral CSA between two measurements was 36 mm² [-42 to 114]. Gastric ultrasonography was significantly more difficult to perform during labor than immediately post-delivery (median difficulty score 5 [2-7] vs. 2 [1-4], P < 0.0001). No risk factors (pain, anxiety, diabetes, smoking) were significantly associated with the occurrence of full stomach post-delivery.

CONCLUSION

This study demonstrated that 48% of parturients in the immediate postpartum period presented an antral CSA ≥ 381 mm² , cut-off being accepted for diagnosis of empty stomach and emphasizes the need for re-assessing before any general anesthetic procedure.

Modified B-ultrasound method for measurement of antral section only to assess gastric function and guide enteral nutrition in critically ill patients

AIM

To establish a modified B-ultrasound method of measuring the antral section only to assess gastric motility in healthy people, and evaluate its application in guiding enteral nutrition (EN) in critically ill patients.

METHODS

First, 30 healthy volunteers were selected. The modified B-ultrasound method and the traditional B-ultrasound method were applied to assess gastric function. The correlation of indices of gastric function between the two groups was analyzed statistically. In addition, 64 critically ill patients were selected, and the modified B-ultrasound method and the gastric juice withdrawal method were applied to guide the implementation of EN. Daily caloric value, the time required to achieve complete EN, ICU stay, hospitalization time, and serum prealbumin and albumin levels were recorded and compared between the two groups. Kaplan-Meier survival curve was used to compare the complications of EN between the two groups.

RESULTS

In healthy subjects, there was a good correlation among gastric emptying time, antral contraction frequency and antral motility index between the two groups (r = 0.57, 0.61 and 0.54, respectively). The study on critically ill patients also revealed that a better effect of EN was achieved in the modified B-ultrasound method group, in which patients had shorter ICU stay and hospitalization time and higher levels of serum prealbumin and albumin. The Kaplan-Meier survival analysis revealed that the improved B-ultrasound method was associated with significantly fewer EN complications (P = 0.031).

CONCLUSION

The modified B-ultrasound method can provide a good real-time assessment of gastric function and has a better effect than the traditional method in guiding EN in critically ill patients.