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.

The correlation between patient satiety sensation and total gastric fluid volume: a prospective observational study.

PURPOSE: Surgical patients are asked to adhere to preoperative fasting guidelines to minimize gastric contents. Large fluid volumes or solid content can still be present as shown with gastric ultrasound. It has been suggested that additional rating of patients' satiety, measured as the feeling of hunger and thirst, could help clinicians to better judge emptying of the stomach. METHODS: We performed a prospective observational study in fasted elective surgical patients. The primary objective was to investigate the correlation between hunger measured on a 0-10 numeric rating scale and total gastric fluid volume measured with gastric ultrasonography. Secondary objectives included the correlation between 1) thirst and total gastric fluid volume and 2) hunger, thirst, and the Perlas grading scale score. RESULTS: We included 515 patients. The exam was inconclusive in 14 individuals (2.7%). The Spearman correlation coefficient between gastric fluid volumes and hunger was 0.11 (95% confidence interval [CI], 0.02 to 0.20) (P = 0.01). The correlation between gastric fluid volumes and thirst was 0.11 (95% CI, 0.02 to 0.20) (P = 0.02). Between antral grades and numeric rating scale, the correlation coefficient was 0.00 (95% CI, -0.09 to 0.09) (P = 1.00) for thirst and 0.00 (95% CI, -0.08 to 0.09) (P = 0.94) for hunger. Ten patients (2.0%) had solid content, 24 presented a grade 2 antrum (4.8%). CONCLUSION: This study suggests that the correlation between total gastric fluid volume and satiety sensation is very weak. Satiety did not reliably predict total gastric fluid volume. STUDY REGISTRATION: ClinicalTrials.gov (NCT04884373); registered 13 May 2021.

RéSUMé: OBJECTIF: On demande aux patient·es de chirurgie de respecter les directives de jeûne préopératoire afin de minimiser leur contenu gastrique. Comme le montre l'échographie gastrique, de grands volumes de liquide ou des solides peuvent encore être présents. Il a été suggéré qu'une évaluation supplémentaire de la satiété des patient·es, mesurée par la sensation de faim et de soif, pourrait aider les clinicien·nes à mieux estimer la vidange de l'estomac. MéTHODE: Nous avons réalisé une étude observationnelle prospective chez des patient·es de chirurgie non urgente à jeun. L'objectif principal était d'étudier la corrélation entre la faim mesurée sur une échelle d'évaluation numérique de 0 à 10 et le volume total de liquide gastrique mesuré par échographie gastrique. Les objectifs secondaires comprenaient la corrélation entre 1) la soif et le volume total de liquide gastrique et 2) la faim, la soif et le score de l'échelle de classement Perlas. RéSULTATS: Nous avons inclus 515 personnes. L'examen était non concluant chez 14 individus (2,7 %). Le coefficient de corrélation de Spearman entre les volumes de liquide gastrique et la faim était de 0,11 (intervalle de confiance [IC] à 95 %, 0,02 à 0,20) (P = 0,01). La corrélation entre les volumes de liquide gastrique et la soif était de 0,11 (IC 95 %, 0,02 à 0,20) (P = 0,02). Entre les grades antraux et l'échelle d'évaluation numérique, le coefficient de corrélation était de 0,00 (IC 95 %, -0,09 à 0,09) (P = 1,00) pour la soif et de 0,00 (IC 95 %, -0,08 à 0,09) (P = 0,94) pour la faim. Un contenu solide a été observé chez dix personnes (2,0 %), et 24 présentaient un antre de grade 2 (4,8 %). CONCLUSION: Cette étude suggère que la corrélation entre le volume total de liquide gastrique et la sensation de satiété est très faible. La satiété n'a pas permis de prédire de manière fiable le volume total de liquide gastrique. ENREGISTREMENT DE L'éTUDE: clinicaltrials.gov (NCT04884373); enregistrée le 13 mai 2021.

Pruritus, neuraxial morphine and recrudescence of oral herpes simplex and treatment: an educational review in obstetric patients.

Neuraxial opioids are well known to cause itching, which may be challenging to treat. Neuraxial morphine has been demonstrated to cause recrudescent herpes simplex viruses (HSV-1), especially in women during labor and childbirth with neuraxial analgesia, and may be an occult etiology of refractory itching. This educational review summaries the clinical and epidemiological characteristics associated with recrudescent HSV-1 in patients treated with neuraxial opioids, especially morphine.

Gastric ultrasound for feeding intolerance in the ICU: close but not quite right.

In the January 2021 issue of BMC Gastroenterology, Elmokadem et al. report their findings on the use of gastric ultrasound (GUS) for the evaluation of feeding intolerance-defined as high gastric residual volume-in critically ill patients. We voice in this correspondence our concerns regarding certain methodological flaws and believe the study results should be interpreted with caution. The authors applied a model unvalidated for non-clear fluids as enteral feeding, the scanning protocol was not clearly described and essential anatomical landmarks required for correct interpretation are not visible in the presented images. Additionally, since GUS was not compared to a gold standard, we believe the authors' conclusion may be overoptimistic and does not undoubtedly answer the primary outcome.

Spinal anesthesia in a patient on monoclonal antibody treatment: a poisoned chalice? A case report.

BACKGROUND: Paraplegia is a rare complication of spinal anesthesia. CASE PRESENTATION: We report a case of a 68-year-old man who developed postoperative paraplegia and hypoesthesia after spinal anesthesia for an otherwise uncomplicated transurethral resection of the prostate. Acute transverse myelitis was diagnosed based on urgent MRI. A prior history of similar though less severe neurological symptoms after obinutuzumab treatment for follicular lymphoma suggested a potential causative role for obinutuzumab, a novel monoclonal antibody that has not been associated with such devastating neurological side effects yet. High-dose steroid treatment partially attenuated the symptoms, but debilitating hypoesthesia and motor deficit remained present 3 months postoperatively. CONCLUSION: The presented case warrants caution when performing neuraxial anesthesia in patients on monoclonal antibody therapies.

Ultrasound assessment of gastric volumes of thick fluids: Validating a prediction model.

BACKGROUND: Enteral nutrition is essential in the treatment of critically ill patients. Current methods to monitor enteral nutrition such as aspiration of residual volume may be inaccurate. Gastric ultrasonography estimates total gastric fluid volume using the Perlas model, but this model is validated for clear fluids only, and its accuracy for measuring thick fluids is unknown. OBJECTIVES: The primary aim of this study was to evaluate the Perlas model for gastric volume estimation of enteral nutrition, a thick fluid product. DESIGN: A single-centre, single blinded, randomised controlled study. SETTING: Single university hospital, from May to July 2019. PARTICIPANTS: Seventy-two healthy fasted volunteers were randomly allocated to different fluid volume groups. INTERVENTION: Participants randomly ingested predetermined volumes between 50 and 400 ml of a feeding-drink (Nutricia Nutridrink). Following a standardised gastric ultrasound scanning protocol, a blinded sonographer measured the antral cross-sectional area in the supine and right-lateral decubitus positions. MAIN OUTCOME MEASURES: Measurements were performed at baseline, 5 min postingestion and 20 min postingestion. Gastric volumes were predicted using the previously established Perlas model and compared with total gastric fluid volumes after ingestion of the study drink. RESULTS: The Perlas model underestimated the volume of thick gastric fluid and yielded a suboptimal fit for our data. However, antral cross-sectional area and total gastric thick fluid volumes were significantly correlated (Pearson's correlation coefficient 0.73, P < 0.01). A new model was fitted to predict gastric volumes of thick fluids, using the antral cross-sectional area (cm2) in the right-lateral decubitus position: Volume (ml) = 79.38 + 13.32 x right-lateral cross-sectional area. CONCLUSION: The Perlas model for clear gastric fluid volume estimation is suboptimal for thick fluid volume assessment and an alternative model is presented. CLINICAL TRIAL REGISTRATION: Netherlands Trial Register Trial NL7677, Registration date: 16 April 2019; https://www.trialregister.nl/trial/7677.

The Obese Patient: Facts, Fables, and Best Practices.

The prevalence of obesity continues to rise worldwide, and anesthesiologists must be aware of current best practices in the perioperative management of the patient with obesity. Obesity alters anatomy and physiology, which complicates the evaluation and management of obese patients in the perioperative setting. Gastric point-of-care ultrasound (PoCUS) is a noninvasive tool that can be used to assess aspiration risk in the obese patient by evaluating the quantity and quality of gastric contents. An important perioperative goal is adequate end-organ perfusion. Standard noninvasive blood pressure (NIBP) is our best available routine surrogate measurement, but is vulnerable to greater inaccuracy in patients with obesity compared to the nonobese population. Current NIBP methodologies are discussed. Obese patients are at risk for wound and surgical site infections, but few studies conclusively guide the exact dosing of intraoperative prophylactic antibiotics for them. We review evidence for low-molecular-weight heparins and weight-based versus nonweight-based administration of vasoactive medications. Finally, intubation and extubation of the patient with obesity can be complicated, and evidence-based strategies are discussed to mitigate danger during intubation and extubation.

Pectoral Nerve Block Type II as the Sole Anesthetic for Removal of a Large Axillary Tumor: A Case Report.

The pectoral nerve block type II (Pecs II block) combined with general anesthesia provides analgesia during breast and axillary surgery. This report describes the first use of the Pecs II block as the sole anesthetic for axillary surgery. A patient needed resection of axillary masses. She was not only very reluctant to have general anesthesia but also considered high risk because of multiple comorbidities. An ultrasound-guided Pecs II block was performed. Both masses were resected without additional sedation or analgesia. This case report suggests that, in selected cases, the Pecs II block can be used as the sole anesthetic for axillary surgery.

Point-of-care ultrasound in pregnancy: gastric, airway, neuraxial, cardiorespiratory.

PURPOSE OF REVIEW: This review focuses on the use of point-of-care ultrasound (PoCUS) in the obstetric context for airway management and assessment of aspiration risk, the placement of neuraxial blocks and the diagnosis and follow-up of cardiorespiratory dysfunction. RECENT FINDINGS: Gastric ultrasound is a useful aspiration risk assessment tool in pregnant patients. Total gastric fluid assessment models and specific cut-offs between high-risk and low-risk stomachs are presented. Airway assessment is useful to detect specific changes in pregnancy and to guide airway management. Handheld ultrasound devices with automated neuraxial landmark detection capabilities could facilitate needle placement in the future. Lung and cardiac ultrasonography is useful in the management of preeclampsia, pulmonary arterial hypertension and peripartum cardiomyopathy. SUMMARY: Owing to its noninvasiveness, ease of accessibility and lack of exposure to radiation, PoCUS plays an increasing and essential role in aspiration risk assessment, airway management, neuraxial anaesthesia and cardiorespiratory diagnosis and decision-making during pregnancy.

Serial Gastric Ultrasound to Evaluate Gastric Emptying After Prokinetic Therapy With Domperidone and Erythromycin in a Surgical Patient With a Full Stomach: A Case Report.

Fasting guidelines are used to prevent perioperative aspiration but they are only reliable in healthy elective patients. Point-of-care gastric ultrasound allows qualitative and quantitative evaluation of gastric contents at the bedside. This case report describes the use of serial gastric point-of-care ultrasound to evaluate the effect of prokinetic therapy with domperidone and erythromycin in an elective surgical patient with multiple comorbidities who presented with a full stomach.

Point-of-care gastric ultrasound and aspiration risk assessment: a narrative review.

This narrative review summarizes the current knowledge on point-of-care ultrasound (POCUS) of gastric contents in order to inform an assessment of aspiration risk and guide anesthetic management at the bedside. An I-AIM framework (Indication, Acquisition, Interpretation, and Medical decision-making) is used to summarize and organize the content areas. This narrative review spans the breadth of the literature on pediatric and adult subjects as well as on special patient populations such as obstetric and severely obese individuals. Areas that need further investigation include the diagnostic accuracy of gastric POCUS from a Bayesian perspective and the impact of POCUS on patient outcomes, healthcare economics, and educational curricula.

Gastric ultrasound to guide anesthetic management in elective surgical patients non-compliant with fasting instructions: a retrospective cohort study.

BACKGROUND: Perioperative aspiration leads to significant morbidity and mortality. Standard fasting periods are used to ensure an empty stomach in patients. Anesthesiologists are frequently confronted with cases of dubious adherence to these guidelines. Point-of-care gastric ultrasound is a diagnostic tool that offers information on the type and volume of gastric contents. METHODS: We performed a retrospective analysis of a departmental database containing clinical and sonographic information on elective surgical patients who had been non-compliant to the fasting guidelines. Primary outcome was the incidence of changes in aspiration risk stratification and anesthetic management when a point-of-care gastric ultrasound examination was added to a standard history-based clinical assessment. Secondary outcomes included type of changes (timing of the surgical procedure or change in anesthetic technique) and the incidence of aspiration. Differences in the management plan (history-based versus gastric ultrasound) were tested with McNemar-Bowker's Exact Test of symmetry. RESULTS: Thirty-seven patients met the inclusion criteria. Aspiration risk assessment and anesthetic management changed in 24 cases (64.9%) following gastric ultrasound. Additionally, there was a non-significant difference in the distribution of the pre- and post-test changes in timing (delay, cancel, proceed) (P=0.074) with a trend towards a lower number of surgical cancellations and a higher number of proceeds. No aspirations were documented. CONCLUSIONS: This retrospective study suggests that gastric ultrasound may be a useful diagnostic addition to standard patient assessment in cases of non-compliance to fasting guidelines. It allows to personalize aspiration risk assessment and to tailor anesthetic management to the individual patient.

Challenges in the anesthetic management of ambulatory patients in the MRI suites.

PURPOSE OF REVIEW: MRI is becoming an indispensable diagnostic tool. The need for prolonged motion-free periods has substantially increased the need for deep sedation or anesthesia in a challenging environment. This review summarises recent literature with respect to pharmacological sedative strategies, nonpharmacological alternative approaches, airway management and safety issues in the ambulatory setting. RECENT FINDINGS: Most literature researches the pediatric patient population. The American Society of Pediatrics published guidelines for monitoring and management of pediatric patients during sedation for diagnostic procedures. Dexmedetomidine is the most researched agent for sedation. It remains uncertain what the clinical implications are of the potential neurotoxicity of repeat sedation or anesthesia in young children. Airway strategies highlight the use of end-tidal carbon dioxide monitoring. Technical imaging advancement and nonpharmacological sedation alternatives allow for shorter procedures with a lower need for sedation. SUMMARY: The anesthetic management of ambulatory patients in the MRI environment has its specific challenges and safety issues. However, the implementation of safety guidelines, new pharmacological and alternative nonpharmacological sedation strategies offer interesting perspectives to tackle these challenges.

Gastric sonography in the severely obese surgical patient: a feasibility study.

BACKGROUND: Gastric ultrasonography allows qualitative and quantitative assessment of gastric contents and volume in nonobese subjects. In this study, we sought to determine the feasibility of gastric ultrasound in severely obese patients (body mass index [BMI] ≥35 kg/m). We defined feasibility as the ability to identify a full cross section of the gastric antrum in at least 80% of subjects when imaged in the right lateral decubitus position. METHODS: This was a prospective cohort study on fasted surgical patients with BMI >35 kg/m. The primary outcome measure was the feasibility of gastric sonography. Secondary outcomes included the distribution of antral grade following an existing 3-point grading system. In addition, the antral cross-sectional area (CSA) and gastric volumes in this cohort were compared with historical data from a published study in nonobese individuals. Time to image capture, antral wall thickness, and depth of the antrum are also reported. RESULTS: Sixty patients (BMI range 35.1-68.7) were studied. The antrum was identified in 95% of subjects in the right lateral decubitus (95% CI, 0.86-0.99) and 90% of subjects in the supine position. Definition of antral grade (0-2) was possible in 88.3% (95% CI, 0.77-0.95) of cases. As expected, antral grade correlated with antral CSA and gastric volumes (P < 0.0001). When compared with historical data, our results suggest that severely obese patients have a larger baseline CSA and gastric volume than nonobese patients (P < 0.001) but a similar gastric volume per unit of weight (P = 0.141). CONCLUSIONS: Gastric ultrasound assessment is feasible in fasted severely obese subjects. Our data also suggest that obese individuals present larger antral size and gastric volume than their nonobese counterparts.