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

STUDY OBJECTIVE

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

DESIGN

Prospective observational study.

SETTING

Tertiary care teaching hospital.

PATIENTS

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

INTERVENTIONS & MEASUREMENTS

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

MAIN RESULTS

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

CONCLUSIONS

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

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.

Preoperative gastric point-of-care ultrasound in nonelective surgical procedures in pediatric-aged patients

Background

Airway management for nonelective surgical procedures in the setting of trauma, pain, and opioid use can be complicated by the potential for aspiration due to delayed gastric emptying. Point-of-care ultrasound (POCUS) remains a useful tool for evaluating gastric content and volume in various clinical settings. The authors evaluated gastric volume and content in children scheduled for urgent and semi-urgent procedures to assess their aspiration risk.

Methods

After obtaining consent, gastric POCUS was performed in the preoperative holding area for pediatric patients scheduled for both elective and nonelective surgery. Qualitative and quantitative measurements of the gastric antrum were taken, and the risk of gastric aspiration was calculated. Additional data collected included patient demographics, the type of surgery, nil per os (NPO) status at the time of surgery, NPO status at the time of injury, and administration of opioids.

Results

The study cohort included 100 patients ranging in age from 3 to 17 years old (mean age 9.2 years). Out of these 100 patients, gastric scanning was successfully conducted in 98 patients. Sixteen of fifty-nine nonelective patients (27%) had received opioids for pain control prior to surgery. Among the 34 patients who had suffered an acute injury, 7 (21%) had been NPO for <8 hours at the time of the injury. Ninety-nine out of hundred patients had been NPO for at least 6 hours at the time of the gastric ultrasound. Based on our gastric ultrasound findings, all patients who were appropriately NPO had either Grade 0 or Grade 1 risk for aspiration, indicating a low risk of aspiration.

Conclusions

The preliminary data show that when patients presenting for nonelective surgery are appropriately NPO, they may have a low risk of aspiration. This information may help guide the choice of anesthetic induction technique, particularly when concerns exist about the safety of a rapid sequence induction. It allows for a more stable and controlled induction of anesthesia.

The effect of preoperative anxiety and ovarian stimulation on gastric antrum size: a prospective observational study

Pulmonary aspiration is a potentially lethal perioperative complication related to gastric size and contents. Several perioperative factors are believed to increase gastric size, while others are less studied. This prospective observational study aimed to investigate the effect of preoperative anxiety and hormone-induced ovarian stimulation on gastric size examined by gastric ultrasound. We recruited 49 female patients undergoing hormone-induced ovarian stimulation and oocyte retrieval for in vitro fertilization at Rabin Medical Centre, Petah Tikva, Israel. Preoperatively, women ranked their anxiety level using a verbal numeric anxiety score (VNS). In addition, we recorded the extent of ovarian stimulation and measured the antral cross-sectional area (CSA) using gastric ultrasound. There was no substantial correlation between preoperative VNS anxiety and antral CSA (p = .697). Moreover, the number of follicles, blood estradiol, and progesterone levels did not correlate with antral CSA (p = .590, p = .104, and p = .511, respectively). In conclusion, neither preoperative anxiety nor extensive ovarian stimulation affects gastric size in fasting healthy patients. However, further studies are warranted in this area to define these findings better. Trial registration: Clinicaltrials.gov, identifier: NCT04833530.

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

BACKGROUND

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

METHODOLOGY

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

RESULTS

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

CONCLUSION

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

Gastric insufflation and surgical view according to mask ventilation method for laparoscopic cholecystectomy: a randomized controlled study

BACKGROUND

Proper mask ventilation is important to prevent air inflow into the stomach during induction of general anesthesia, and it is difficult to send airflow only through the trachea without gastric inflation. Changes in gastric insufflation according to mask ventilation during anesthesia induction were compared.

METHODS

In this prospective, randomized, single-blind study, 230 patients were analyzed to a facemask-ventilated group (Ventilation group) or no-ventilation group (Apnea group) during anesthesia induction. After loss of consciousness, pressure-controlled ventilation at an inspiratory pressure of 15 cmH2O was performed for two minutes with a two-handed mask-hold technique for Ventilation group. For Apnea group, only the facemask was fitted to the face for one minute with no ventilation. Next, endotracheal intubation was performed. The gastric cross-sectional area (CSA, cm2) was measured using ultrasound before and after induction. After pneumoperitoneum with carbon dioxide, gastric insufflation of the surgical view was graded by the surgeon for each group.

RESULTS

Increase of postinduction antral CSA on ultrasound were not significantly different between Ventilation group and Apnea group (0.04 ± 0.3 and 0.02 ± 0.28, p-value = 0.225). Additionally, there were no significant differences between the two groups in surgical grade according to surgeon's judgement.

CONCLUSIONS

Pressure-controlled ventilation at an inspiratory pressure of 15 cmH2O for two minutes did not increase gastric antral CSA and insufflation of stomach by laparoscopic view.

TRIAL REGISTRATION

http://cris.nih.go.kr (KCT0003620) on 13/3/2019.

Assessment of residual gastric volume using point-of-care ultrasonography in adult patients who underwent elective surgery

BACKGROUND

Aspiration pneumonitis remains a dreaded complication that may lead to almost 9% of anaesthesia-related deaths. The presence of gastric contents has always been a contributing factor to an increased risk of aspiration. Preoperative gastric ultrasound has been suggested as a modality for determining residual volume in special populations and conditions. We conducted an observational study to determine the gastric residual volume in preoperative patients of elective surgery with gastric ultrasound and to study its correlation with patient factors.

METHODS

We enrolled 411 patients in the age group of 18-80 with ASA-PS I and II having BMI less than 35 kg/m². Patients with prior gastrointestinal surgery and parturients were excluded from the present study. Gastric antrum in both supine and right lateral decubitus positions was measured using USG in the immediate preoperative period, and gastric residual volume was calculated, which was subsequently correlated with various patient factors.

RESULTS

On qualitative assessment, 97 and 118 patients were observed to have distended stomachs in the supine and right lateral decubitus positions, respectively. On quantitative assessment, 336 had safe GRV, 60 patients were classified as having a low risk of aspiration (GRV < 1.5 ml/kg) while 13 had a high risk of aspiration (> 1.5 ml/kg). Eight patients with a fasting duration of more than ten hours and five who fasted between 6 and 10 h had a gastric residual volume of more than 1.5 ml/h. Patients who were premedicated with histamine blockers had a statistically significant higher antral cross-sectional area (p-value - 0.022*) and GRV (p-value - 0.018*) in the right lateral decubitus position compared to patients who had taken proton pump inhibitors (PPIs). As BMI increased, there was a statistically significant (p-value < 0.001) increase in mean antral CSA in both supine and right lateral decubitus positions. There was a statistically significant association found between type 2 diabetes (p-value 0.045*) with antral grade.

DISCUSSION

Patients can have significant residual volume (> 1.5 ml/kg) despite adequate fasting, and preoperative gastric ultrasound can help in assessing the same and guiding perioperative airway management. PPIs are more effective in reducing gastric residual volume as compared to histamine blockers. Patients with a BMI of more than 30 and type 2 diabetes mellitus have significant correlation with increased gastric residual volume mandating preoperative gastric ultrasound assessment for effective management.

CONCLUSIONS

Patients with BMI over 30 and type 2 diabetes may benefit from POCGUS to guide perioperative airway management by stratifying GRV. Trial registration Name of registry-Clinical Trial Registry of India. Trial registration number-2020/03/024083. Date of registration-19.3.2020. URL- http://ctri.nic.in/Clinicaltrials/pmaindet2.php?trialid=39961&EncHid=&userName=.

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.

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.

Evaluation of gastric contents using ultrasound in full-term pregnant women fasted for 8 h: a prospective observational study

BACKGROUND

We aimed to evaluate the gastric volume and contents after an 8-h fasting period in full-term, non-laboring, pregnant women following a standardized meal.

METHODS

In this prospective observational study, we included full-term pregnant women scheduled for elective cesarean delivery. The participants were instructed to fast after a standardized meal (apple juice, bread, and cheese). Participants were scanned in the semi-recumbent and right-lateral positions 8 h after the standardized meal. The primary outcome was the proportion of patients with gastric volume > 1.5 mL kg^-1 calculated by two equations. Secondary outcomes included the antral cross-sectional area and gastric volume. Data are expressed as frequency (%, 95% confidence interval [CI]), mean ± standard deviation (95% CI of the mean), or median (quartiles) as appropriate.

RESULTS

Forty-one women were available for the final analysis. For the primary outcome, one participant (2.4%, 95% CI of 0.06 to 12.8%) had gastric volume > 1.5 mL kg^-1, and none had solids in the antrum. For the secondary outcomes, the mean (95% CI of the mean) of the antral cross-sectional area was 2.11 ± 0.72 (1.88 to 2.34) cm² and 4.08 ± 1.80 (3.51 to 4.65) cm² during the semi-recumbent and right-lateral position, respectively. The median (quartiles) gastric volume was 0.53 (0.32, 0.66) mL kg^-1 and 0.33 (0.13, 0.52) mL kg^-1 as estimated by Perlas et al. and Roukhomovsky et al. equations, respectively.

CONCLUSION

After 8-h fasting following a standardized meal, full-term pregnant non-laboring women are less likely to have a high residual gastric volume.

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

BACKGROUND

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

MATERIAL AND METHODS

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

MAIN FINDINGS

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

CONCLUSION

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

Prediction of postoperative nausea and vomiting by point-of-care gastric ultrasound: can we improve complications and length of stay in emergency surgery? A cohort study

Background

Postoperative nausea and vomiting and postoperative ileus are common after major digestive surgery and represent one of the significant problems in Acute Care Surgery.

The delivery model of emergency surgery needs to be improved in order to foster a patient-centered care.

The multimodal approach suggested by Enhanced Recovery After Surgery (ERAS®) Guidelines is gaining widespread acceptance but is difficult to apply to emergency surgery.

Ultrasound examination of the gastric antrum allows a reliable assessment of gastric contents and volume and might help contribute to improve perioperative care in the emergency setting.

Methods

Gastric ultrasound examinations were performed preoperatively and postoperatively on forty-one patients undergoing emergency abdominal surgery. Gastric cross-sectional area (CSA) was measured, in order to estimate the gastric volume. The data obtained were used to evaluate a possible relationship between delayed gastric emptying and postoperative adverse event.

Results

Gastric antrum detection rate varied from 31.8% in open up to 78.9% in laparoscopic surgeries (p = 0.003). Six patients experienced adverse outcomes, had an antiemetic therapy administered and/or a nasogastric tube inserted. Mean CSA was significantly higher in this group (12.95 cm² vs 6.12 cm²; p = 0.040).

Conclusions

Sensitivity of gastric ultrasound varies depending on surgical technique. A dilated gastric antrum is significantly related to postoperative adverse outcomes and a careful ultrasound follow-up might help tailor postoperative nutrition and antiemetic therapy. In patients who experienced adverse events, antral CSA showed an average increase of more than 50% over a period of 72 h after surgery. A relative measure could be used to predict the risk of postoperative ileus. Overall, gastric ultrasound seems to be a promising diagnostic tool and a useful way to integrate ERAS® protocol in emergency abdominal surgery.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The effects of diabetes mellitus on gastric emptying: A prospective observational cohort study

STUDY OBJECTIVE

Our goal was to evaluate the effect of diabetic severity and duration on preoperative residual gastric volume. Secondarily we compared ultrasonic estimates of residual gastric volume with actual volume determined by aspiration during endoscopy.

DESIGN

This was a prospective, observational cohort study that included adults with a history of diabetes mellitus and/or opioid use scheduled for gastrointestinal endoscopic procedures.

SETTING

Endoscopy unit at Cleveland Clinic Main Campus from 2017 to 2019.

PARTICIPANT

Adults scheduled for upper endoscopy with or without colonoscopy.

INTERVENTION AND MEASUREMENTS

Residual gastric volumes were primarily determined by aspiration during endoscopy, and secondarily estimated with ultrasound. We evaluated the relationship between gastric residual volume and preoperative HBA1C concentration and duration of diabetes. Secondarily, we conducted an agreement analysis between the two gastric volume measurement techniques.

MAIN RESULTS

Among 145 enrolled patients, 131 were diabetic and 17 were chronic opioid users. Among 131 diabetic patients, the mean ± SD HbA1c was 7.2 ± 1.5% and the median (Q1, Q3) duration of diabetes was 8.5 (3, 15) years. Neither HbA1c nor duration of diabetes was associated with residual gastric volume. The adjusted mean ratio of residual gastric volume was 1.07 (98.3% CI: 0.89, 1.28; P = 0.38) for 1% increase in HbA1c concentration, and 0.84 (98.3% CI: 0.63, 1.14; P = 0.17) for each 10-year increase induration of diabetes. The median [Q1-Q3] absolute difference between gastric ultrasound measurement and endoscopic measurement was 25 [15, 65] ml.

CONCLUSIONS

In this prospective observational cohort study, neither the duration nor severity of diabetes influenced preoperative residual gastric volume. Gastric ultrasound can help identify patients who have excessive residual volumes despite overnight fasting.

Ultrasound: The New Stethoscope (Point-of-Care Ultrasound)

Advances in technology have led to more user-friendly ultrasound devices that allow for easy incorporation into daily perioperative practice, with the anesthesiologist serving as the sonographer. With appropriate knowledge and training, bedside ultrasound examinations can be used to better diagnose pathology and guide perioperative strategies. Cardiac ultrasound examination was the initial emphasis in anesthesiology, with now expansion into lung and gastric ultrasound imaging. In this review, the indications, procedural description, and clinical findings for lung and gastric ultrasound examinations are discussed to demonstrate its importance and build confidence in the user.

Routine point-of-care ultrasound (POCUS) assessment of gastric antral content in traumatic emergency surgical patients for prevention of aspiration pneumonitis: an observational clinical trial

BACKGROUND

Polytrauma patients are at a higher risk of delayed gastric emptying. To assess the gastric volume, a reliable diagnostic tool is needed to prevent the occurrence of aspiration pneumonia, which remains a serious complication associated with anesthesia. Gastric antral ultrasound can provide reliable information about the size of the gastric antrum in traumatized patients undergoing emergency surgery.

METHODS

A prospective observational study of 45 polytrauma patients undergoing emergency surgery under general anesthesia was carried out. Prior to induction of anesthesia in the emergency department, gastric ultrasound was performed for qualitative and quantitative assessment of the gastric antrum in a supine position and right lateral decubitus (RLD) position. This was followed by routine placement of the nasogastric tube to aspirate and calculate the volume of the stomach contents.

RESULTS

Of the 45 polytrauma patients, the risk assessment of aspiration and the anesthesia technique changed in 14 patients (31.1%) after the gastric ultrasound examination. A very good relationship existed between the expected stomach volume at the RLD position and the suction volume in the nasogastric tube. In all cases, no aspirations were documented.

CONCLUSION

Ultrasound examination of the stomach in polytrauma patients allows assessing the size and type of stomach contents. The data obtained can influence the choice of anesthesia technique and reduce the risk of aspiration pneumonia.

TRIAL REGISTRATION

This trial was registered at ClinicalTrials.gov . registry number: NCT04083677 on September 6, 2019.

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.

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 ± 32.69 mL in the DGEF versus 53.50 ± 30.72 mL in the non-DGEF group (p = 0.08). Average volume per unit of weight was 0.61 ± 0.46 mL/kg. Only 1 patient in the DGEF group had a volume that posed a higher risk of aspiration (1.57 mL/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.

[Comparative ultrasound study of gastric emptying between an isotonic solution and a nutritional supplement]

BACKGROUND AND OBJECTIVES

Preoperative fasting may lead to undesirable effects in the surgical patient in whom there is a stimulus to ingesting clear liquids until 2hours before anesthesia. The aim of this study was to evaluate the gastric emptying of two different solutions using ultrasound.

METHODS

In a prospective, randomized, blind study, 34 healthy volunteers ingested 200mL of two solutions without residues in two steps: an isotonic solution with carbohydrates, electrolytes, osmolarity of 292 mOsm.L^-1, and 36 kcal; and other nutritional supplementation with carbohydrates, proteins, electrolytes, osmolarity of 680 mO.L^-1, and 300 kcal. After 2hours, a gastric ultrasound was performed to assess the antrum area and gastric volume, and the relation of gastric volume to weight (vol.w^-1), whose value above 1.5mL.kg^-1 was considered a risk for bronchoaspiration. A p-value <0.05 was considered statistically significant.

RESULTS

There was a significant difference between all parameters evaluated 2hours after the ingestion of nutritional supplementation compared to fasting. The same occurred when the parameters between isotonic solution and nutritional supplementation were compared 2hours after ingestion. Only one patient had vol.w^-1 <1.5mL.kg^-1 2hours after ingestion of nutritional supplementation; and only one had vol.w^-1> 1.5mL.kg^-1 after ingestion of isotonic solution.

CONCLUSION

This study demonstrated that gastric emptying of equal volumes of different solutions depends on their constitution. Those with high caloric and high osmolarity, and with proteins present, 2hours after ingestion, increased the gastric volumes, which is compatible with the risk of gastric aspiration.

[Use of ultrasound for gastric volume evaluation after ingestion of different volumes of isotonic solution]

BACKGROUND AND OBJECTIVES

The current preoperative fasting guidelines allow fluid intake up to 2hours before surgery. The aim of this study was to evaluate the gastric volume of volunteers after an overnight fast and compare it with the gastric volume 2hours after ingestion of 200 and 500mL of isotonic solution, by means of ultrasound assessment.

METHOD

Eighty volunteers underwent gastric ultrasound at three times: after 8hours of fasting; 2hours after ingestion of 200mL isotonic saline, followed by the first scan; and on another day, 2hours after ingestion of 500mL of the same solution after an overnight fast. The evaluation was quantitative (antrum area and gastric volume, and the ratio of participants' gastric volume/weight) and qualitative (absence or presence of gastric contents on right lateral decubitus and supine positions. A p-value<0.05 was considered significant).

RESULTS

There was no difference in quantitative variables at measurement times (p>0.05). Five volunteers (6.25%) had a volume/weight over 1.5mL.kg^-1 at fasting and 2hours after ingestion of 200mL and 6 (7.5%) after 500mL. Qualitatively, the presence of gastric fluid occurred in more volunteers after fluid ingestion, especially 500mL (18.7%), although not statistically significant.

CONCLUSION

Ultrasound assessment of gastric volume showed no significant difference, both qualitative and quantitative, 2h after ingestion of 200mL or 500mL of isotonic solution compared to fasting, although gastric fluid content has been identified in more volunteers, especially after ingestion of 500mL isotonic solution.