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

Ultrasound monitoring to detect embolic phenomena in the inferior vena cava during hip arthroplasty

INTRODUCTION AND OBJECTIVES

Embolic phenomena frequently occur during hip joint replacement surgery, and may lead to haemodynamic instability in frail patients. Transoesophageal ultrasound monitoring is rarely available in non-cardiac operating theatres, and cannot be performed in awake patients under spinal anaesthesia. The main objectives of this prospective exploratory study were to determine the feasibility of using an alternative ultrasound approach to monitor the inferior vena cava during hip replacement surgery, and to determine the intra and interobserver reliability of the ultrasound findings.

METHOD

We conducted a prospective exploratory study in 20 patients undergoing cemented hip arthroplasty in the supine position under spinal anaesthesia and sedation. The inferior vena cava was assessed through a subcostal window at 10 intraoperative time points, and the findings were rated on a qualitative embolism severity scale. The ultrasound images were evaluated by 2 independent observers.

RESULTS

An adequate subcostal window was obtained in 90% of cases. Intra- and inter-observer reliability was high (kappa index >0.80, p < 0.001). Nearly all (95%) patients presented some degree of embolism, which was severe in 50% of cases.

CONCLUSIONS

Our study suggests that ultrasound assessment of embolic phenomena in the inferior vena cava through a subcostal window is feasible in 90% of cases. The qualitative embolic severity rating scale is highly reproducible and has high intra- and inter-observer reliability.

Baseline Gastric Volume in Fasting Diabetic Patients Is Not Higher than That in Nondiabetic Patients: A Cross-sectional Noninferiority Study

BACKGROUND

The physiology of diabetes mellitus can increase the risk of perioperative aspiration, but there is limited and contradictory evidence on the incidence of "full stomach" in fasting diabetic patients. The aim of this study is to assess the baseline gastric content (using gastric ultrasound) in diabetic and nondiabetic patients scheduled for elective surgery who have followed standard preoperative fasting instructions.

METHODS

This was a prospective, noninferiority study of 180 patients (84 diabetic and 96 nondiabetic patients). Bedside ultrasound was used for qualitative and quantitative assessment of the gastric antrum in the supine and right lateral decubitus positions. Fasting gastric volume was estimated based on the cross-sectional area of the gastric antrum and a validated model. The hypothesis was that diabetic patients would not have a higher baseline fasting gastric volume compared to nondiabetic patients, with a noninferiority margin of 0.4 ml/kg. Secondary aims included the comparison of the incidence of full stomach (solid content or more than 1.5 mL/kg of clear fluid), estimation of the 95th percentile of the gastric volume distribution in both groups, and examination of the association between gastric volume, glycemic control, and diabetic comorbidities.

RESULTS

The baseline gastric volume was not higher in diabetic patients (0.81 ± 0.61 ml/kg) compared to nondiabetic patients (0.87 ± 0.53 ml/kg) with a mean difference of -0.07 ml/kg (95% CI, -0.24 to 0.10 ml/kg). A total of 13 (15.5%) diabetic and 11 (11.5%) nondiabetic patients presented more than 1.5 ml/kg of gastric volume (95% CI for difference, -7.1 to 15.2%). There was little correlation between the gastric volume and either the time since diagnosis or HbA1C.

CONCLUSIONS

The data suggest that the baseline gastric volume in diabetic patients who have followed standard fasting instructions is not higher than that in nondiabetic patients.

EDITOR’S PERSPECTIVE

Point-of-Care Gastric Ultrasound to Identify a Full Stomach on a Diabetic Patient Taking a Glucagon-Like Peptide 1 Receptor Agonist

Recently, there has been increased interest in the relationship between glucagon-like peptide 1 (GLP-1) receptor agonists, delayed gastric emptying, and subsequent risk of aspiration in the perioperative setting. This case illustrates how gastric ultrasound can be incorporated at the bedside to assess the risk of aspiration in patients taking this type of medication for diabetes or weight loss and guide clinical management and anesthetic technique to reduce the risk of aspiration.

Standardizing nomenclature in regional anesthesia: an ASRA-ESRA Delphi consensus study of upper and lower limb nerve blocks

BACKGROUND

Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks.

METHODS

We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as ≥75% agreement and weak consensus as 50%-74% agreement.

RESULTS

A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research.

CONCLUSIONS

We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.

Validation of a novel point-of-care ultrasound method to assess diaphragmatic excursion

INTRODUCTION

Point-of-care ultrasound can assess diaphragmatic function and rule in or rule out paresis of the diaphragm. While this is a useful bedside tool, established methods have significant limitations. This study explores a new method to assess diaphragmatic motion by measuring the excursion of the uppermost point of the zone of apposition (ZOA) at the mid-axillary line using a high-frequency linear ultrasound probe and compares it with two previously established methods: the assessment of the excursion of the dome of the diaphragm (DOD) and the thickening ratio at the ZOA.

METHODS

This is a single-centre, prospective comparative study on elective surgical patients with normal diaphragmatic function. Following research ethics board approval and patient written consent, 75 elective surgical patients with normal diaphragmatic function were evaluated preoperatively. Three ultrasound methods were compared: (1) assessment of the excursion of the DOD using a curvilinear probe through an abdominal window; (2) assessment of the thickening fraction of the ZOA; and (3) assessment of the excursion of the ZOA. The last two methods performed with a linear probe on the lateral aspect of the chest.

RESULTS

Seventy-five patients were studied. We found that the evaluation of the excursion of the ZOA was more consistently successful (100% bilaterally) than the evaluation of the excursion of the DOD (98.7% and 34.7% on the right and left sides, respectively). The absolute values of the excursion of the ZOA were greater than and well correlated with the values of the DOD.

CONCLUSION

Our preliminary data from this exploratory study suggest that the evaluation of the excursion of the ZOA on the lateral aspect of the chest using a linear probe is consistently successful on both right and left sides. Future studies are needed to establish the distribution of normal values and suggest diagnostic criteria for diaphragmatic paresis or paralysis.

TRIAL REGISTRATION NUMBER

NCT03225508.

Gastric Point of Care Ultrasound in Adults: Image Acquisition and Interpretation

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical inquiries related to gastric content. One emerging concern pertains to patients about to undergo sedation and/or endotracheal intubation: the elevated risk of aspiration from the patient's stomach contents. Aspiration of gastric contents into the lungs poses a serious and potentially life-threatening complication. This occurs more frequently when the stomach is considered "full" and can be affected by the techniques employed for airway management, making it potentially preventable. To mitigate the risk of peri-procedural aspiration, two distinct medical specialties (anesthesiology and critical care medicine) have independently developed techniques to utilize ultrasonography for identifying patients requiring "full stomach" precautions. Due to these separate specialties, the work of each group remains relatively unfamiliar outside its respective field. This article presents descriptions of both techniques for gastric ultrasound. Furthermore, it explains how these approaches can complement each other when one of them falls short. Regarding image acquisition, the article covers the following topics: indications and contraindications, selection of the appropriate probe, patient positioning, and troubleshooting. The article also delves into image interpretation, complete with example images. Additionally, it demonstrates how one of the two techniques can be employed to estimate gastric fluid volume. Lastly, the article briefly discusses medical decision-making based on the findings of this examination.

A hood shield reduces postdoffing contamination during simulated COVID-19 airway management: an exploratory, simulation-based randomized study

PURPOSE

SARS-CoV-2 poses a significant occupational health threat to health care workers performing aerosol-generating medical procedures, with a threefold increased risk of a positive test and predicted infection compared with the general population. Nevertheless, the personal protective equipment (PPE) configuration that provides better protection with lower contamination rates is still unknown.

METHODS

We enrolled 40 practitioners with airway management training (anesthesiologists, anesthesia assistants/nurses) in an exploratory, simulation-based randomized study. We evaluated the performance of a novel, locally designed hood (n = 20) in terms of protection from surrogate contamination using an ultraviolet (UV) marker during a standardized urgent intubation procedure and a simulated episode of coughing in a high-fidelity simulation setting compared with standard PPE (n = 20). The primary outcome was the presence of residual UV fluorescent contamination on any base clothing or exposed skin of the upper body after doffing PPE assessed by a blinded evaluator.

RESULTS

The proportion of participants with residual contamination on any base clothing or exposed skin of the upper body after doffing was less than half in the hood PPE group compared with the standard PPE group (8/20 [40%] vs 18/20 [90%], respectively; P = 0.002).

CONCLUSIONS

Compared with standard PPE, enhanced PPE with a locally designed prototype hood was associated with reduced contamination of the upper torso and fewer body areas being exposed to droplets after a simulated aerosol-generating scenario without designed airflow.

STUDY REGISTRATION

ClinicalTrials.gov (NCT04373096); registered 4 May 2020.

Preoperative fasting for the infusion of "yerba mate": a randomized clinical trial with ultrasound evaluation of gastric contents

BACKGROUND

The traditional infusion of "yerba mate" is widely consumed in South America and exported to countries around the world. Although generally considered a "clear fluid", there is no data to date on the gastric emptying time of yerba mate and safe preoperative fasting intervals. The objective of this study was to evaluate the gastric emptying time of a standardized infusion of yerba mate using bedside ultrasound and compare it with the time confirm of hot and cold tea.

METHODS

This was a prospective, randomized crossover experimental study. Thirty healthy volunteers were evaluated after 8 hours of fasting for both fluids and solids. Gastric antral area and gastric volume were evaluated at baseline and every 20 minutes after drinking 300 mL of randomly assigned infusion of "yerba mate", hot tea, or cold tea.

RESULTS

The mean gastric emptying time was: 69.7 ± 22.1 min, 63.1 ± 14.5 min, and 64.3 ± 23.5 min for the mate, hot tea, and cold tea respectively. No significant differences were found in emptying time among the infusion groups (p-value = 0.043). When same time measures were compared, the only significant difference detected was between hot teas and mate infusion at 20 minutes (p-value = 0.012) CONCLUSION: Yerba mate infusion has a similar gastric emptying time to that of tea. All subject's gastric volume returned to baseline values by 100 minutes. It is reasonable to recommend a similar fasting period of 2 hours for mate infusion prior to elective surgery.

Impact of fasting on the gastric volume of critically ill patients before extubation: a prospective observational study using gastric ultrasound

Background

A period of fasting before tracheal extubation of ventilated patients in the ICU is common practice, aiming to reduce gastric volume and aspiration risk. As the volume of gastric content is unknown at the time of extubation, the efficacy of this practice is uncertain.

Methods

A prospective, observational study using gastric ultrasound was undertaken. Images were obtained at four time points: (i) at baseline, with gastric feeds running; (ii) after suctioning of gastric contents through a gastric tube; (iii) after a 4 h period with no gastric feed running; and (iv) after both a 4 h fasting period and gastric tube suctioning. The primary outcome was the proportion of patients classed as low risk of aspiration with each intervention, using qualitative and quantitative gastric ultrasound.

Results

Fifty-four patients in the ICU were enrolled. Forty-four (81%) subjects had images that were suitable for analysis. Suctioning of stomach content through a gastric tube and fasting were equivalent with 39/44 (88.6%) and 5/44 (11.4%) subjects classified as low risk and at risk of aspiration, respectively. A period of fasting followed by suction resulted in 41/44 (93.2%) patients being at low risk.

Conclusions

Suctioning of stomach contents through the gastric tube and a 4 h fasting period appear equivalent at reducing gastric volume below a safe threshold. A small percentage did not reach the threshold despite all interventions.

Recommendations for effective documentation in regional anesthesia: an expert panel Delphi consensus project

Background and objectives

Documentation is important for quality improvement, education, and research. There is currently a lack of recommendations regarding key aspects of documentation in regional anesthesia. The aim of this study was to establish recommendations for documentation in regional anesthesia.

Methods

Following the formation of the executive committee and a directed literature review, a long list of potential documentation components was created. A modified Delphi process was then employed to achieve consensus amongst a group of international experts in regional anesthesia. This consisted of 2 rounds of anonymous electronic voting and a final virtual round table discussion with live polling on items not yet excluded or accepted from previous rounds. Progression or exclusion of potential components through the rounds was based on the achievement of strong consensus. Strong consensus was defined as ≥75% agreement and weak consensus as 50%–74% agreement.

Results

Seventy-seven collaborators participated in both rounds 1 and 2, while 50 collaborators took part in round 3. In total, experts voted on 83 items and achieved a strong consensus on 51 items, weak consensus on 3 and rejected 29.

Conclusion

By means of a modified Delphi process, we have established expert consensus on documentation in regional anesthesia.

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.

Standardizing nomenclature in regional anesthesia: an ASRA-ESRA Delphi consensus study of abdominal wall, paraspinal, and chest wall blocks

BACKGROUND

There is heterogeneity in the names and anatomical descriptions of regional anesthetic techniques. This may have adverse consequences on education, research, and implementation into clinical practice. We aimed to produce standardized nomenclature for abdominal wall, paraspinal, and chest wall regional anesthetic techniques.

METHODS

We conducted an international consensus study involving experts using a three-round Delphi method to produce a list of names and corresponding descriptions of anatomical targets. After long-list formulation by a Steering Committee, the first and second rounds involved anonymous electronic voting and commenting, with the third round involving a virtual round table discussion aiming to achieve consensus on items that had yet to achieve it. Novel names were presented where required for anatomical clarity and harmonization. Strong consensus was defined as ≥75% agreement and weak consensus as 50% to 74% agreement.

RESULTS

Sixty expert Collaborators participated in this study. After three rounds and clarification, harmonization, and introduction of novel nomenclature, strong consensus was achieved for the names of 16 block names and weak consensus for four names. For anatomical descriptions, strong consensus was achieved for 19 blocks and weak consensus was achieved for one approach. Several areas requiring further research were identified.

CONCLUSIONS

Harmonization and standardization of nomenclature may improve education, research, and ultimately patient care. We present the first international consensus on nomenclature and anatomical descriptions of blocks of the abdominal wall, chest wall, and paraspinal blocks. We recommend using the consensus results in academic and clinical practice.

Gastric content and perioperative pulmonary aspiration in patients with diabetes mellitus: a scoping review

BACKGROUND

Gastric emptying may be delayed in patients with diabetes mellitus (DM). However, the incidence of full stomach in fasting patients with DM and their risk of pulmonary aspiration under anaesthesia is not well understood.

METHODS

A scoping review was undertaken to map the literature on aspiration risk in DM. A search was conducted in seven bibliographic databases, including MEDLINE and Embase, for original articles that studied aspiration risk, gastric emptying, or gastric content and volume. Selection and characterisation were performed by two independent reviewers using a predefined protocol registered externally.

RESULTS

The search identified 5063 unique records, and 16 studies (totalling 775 patients with DM) were selected: nine studied gastric emptying and seven studied gastric content or volume. There were no studies reporting the incidence of aspiration in subjects with DM. All nine studies reported delayed emptying in patients with DM compared with healthy controls. Amongst the seven studies that compared gastric residual content/volume (GRV) in the perioperative period, five reported clinically negligible GRV in both patients with DM and controls, whereas two observed a higher incidence of 'full' stomach in patients with DM.

CONCLUSIONS

The evidence concerning the aspiration risk for surgical patients with DM is based on a limited number of studies, mostly unblinded, reporting physiological data on gastric emptying and gastric volume as surrogate markers of aspiration risk. Data on fasting gastric content and volume in patients with DM are limited and contradictory; hence, the true risk of aspiration in fasting patients with DM is unknown.

Diagnostic Point-of-Care Ultrasound: Recommendations From an Expert Panel

Diagnostic point-of-care ultrasound (PoCUS) has emerged as a powerful tool to help anesthesiologists guide patient care in both the perioperative setting and the subspecialty arenas. Although anesthesiologists can turn to guideline statements pertaining to other aspects of ultrasound use, to date there remains little in the way of published guidance regarding diagnostic PoCUS. To this end, in 2018, the American Society of Anesthesiologists chartered an ad hoc committee consisting of 23 American Society of Anesthesiologists members to provide recommendations on this topic. The ad hoc committee convened and developed a committee work product. This work product was updated in 2021 by an expert panel of the ad hoc committee to produce the document presented herein. The document, which represents the consensus opinion of a group of practicing anesthesiologists with established expertise in diagnostic ultrasound, addresses the following issues: (1) affirms the practice of diagnostic PoCUS by adequately trained anesthesiologists, (2) identifies the scope of practice of diagnostic PoCUS relevant to anesthesiologists, (3) suggests the minimum level of training needed to achieve competence, (4) provides recommendations for how diagnostic PoCUS can be used safely and ethically, and (5) provides broad guidance about diagnostic ultrasound billing.

American Society of Regional Anesthesia and Pain Medicine expert panel recommendations on point-of-care ultrasound education and training for regional anesthesiologists and pain physicians-part II: recommendations

Point-of-care ultrasound (POCUS) is a critical skill for all regional anesthesiologists and pain physicians to help diagnose relevant complications related to routine practice and guide perioperative management. In an effort to inform the regional anesthesia and pain community as well as address a need for structured education and training, the American Society of Regional Anesthesia and Pain Medicine Society (ASRA) commissioned this narrative review to provide recommendations for POCUS. The recommendations were written by content and educational experts and were approved by the guidelines committee and the Board of Directors of the ASRA. In part II of this two-part series, learning goals and objectives were identified and outlined for achieving competency in the use of POCUS, specifically, airway ultrasound, lung ultrasound, gastric ultrasound, the focus assessment with sonography for trauma exam, and focused cardiac ultrasound, in the perioperative and chronic pain setting. It also discusses barriers to POCUS education and training and proposes a list of educational resources. For each POCUS section, learning goals and specific skills were presented in the Indication, Acquisition, Interpretation, and Medical decision-making framework.

American Society of Regional Anesthesia and Pain Medicine expert panel recommendations on point-of-care ultrasound education and training for regional anesthesiologists and pain physicians-part I: clinical indications

Point-of-care ultrasound (POCUS) is a critical skill for all regional anesthesiologists and pain physicians to help diagnose relevant complications related to routine practice and guide perioperative management. In an effort to inform the regional anesthesia and pain community as well as address a need for structured education and training, the American Society of Regional Anesthesia and Pain Medicine (ASRA) commissioned this narrative review to provide recommendations for POCUS. The guidelines were written by content and educational experts and approved by the Guidelines Committee and the Board of Directors of the ASRA. In part I of this two-part series, clinical indications for POCUS in the perioperative and chronic pain setting are described. The clinical review addresses airway ultrasound, lung ultrasound, gastric ultrasound, the focus assessment with sonography for trauma examination and focused cardiac ultrasound for the regional anesthesiologist and pain physician. It also provides foundational knowledge regarding ultrasound physics, discusses the impact of handheld devices and finally, offers insight into the role of POCUS in the pediatric population.

Surgical anesthesia for proximal arm surgery in the awake patient

This education article discusses a combination of brachial plexus and peripheral nerve blocks aimed at providing complete surgical anesthesia to the proximal arm, while consistently avoiding diaphragmatic paresis. This type of approach may be warranted in patients with respiratory compromise of any etiology. In these settings awake surgery is recommended to preserve respiratory function and at the same time minimize the risk of infection of the healthcare team by avoiding the aerosol-generating medical procedures associated with general anesthesia.

Infectivity and pathobiology of H7N1 and H5N8 high pathogenicity avian influenza viruses for pigeons (Columba livia var. domestica)

Avian influenza (AI) is one of the most important viral diseases in poultry, wildlife and humans. Available data indicate that pigeons play a minimum role in the epidemiology of AI. However, a degree of variation exists in the susceptibility of pigeons to highly pathogenic AI viruses (HPAIVs), especially since the emergence of the goose/Guangdong H5 lineage. Here, the pathogenesis of H5N8 HPAIV in comparison with a H7N1 HPAIV and the role of pigeons in the epidemiology of these viruses were evaluated. Local and urban pigeons (Columba livia var. domestica) were intranasally inoculated with 10⁵ ELD₅₀ of A/goose/Spain/IA17CR02699/2017 (H5N8) or A/Chicken/Italy/5093/1999 (H7N1) and monitored during 14 days. Several pigeons inoculated with H5N8 or H7N1 seroconverted. However, clinical signs, mortality, microscopic lesions and viral antigen were only detected in a local pigeon inoculated with H5N8 HPAIV. This pigeon presented prostration and neurological signs that correlated with the presence of large areas of necrosis and widespread AIV antigen in the central nervous system, indicating that the fatal outcome was associated with neurological dysfunction. Viral RNA in swabs was detected in some pigeons inoculated with H7N1 and H5N8, but it was inconsistent, short-term and at low titres. The present study demonstrates that the majority of pigeons were resistant to H5N8 and H7N1 HPAIVs, despite several pigeons developing asymptomatic infections. The limited viral shedding indicates a minimum role of pigeons as amplifiers of HPAIVs, regardless of the viral lineage, and suggests that this species may represent a low risk for environmental contamination. RESEARCH HIGHLIGHTS H7N1 and H5N8 HPAIVs can produce subclinical infections in pigeons. The mortality caused by H5N8 HPAIV in one pigeon was associated with neurological dysfunction. Pigeons represent a low risk for environmental contamination by HPAIVs.

Experimental infection of domestic geese (Anser anser var. domesticus) with H5N8 Gs/GD and H7N1 highly pathogenic avian influenza viruses

Prior to the emergence of the Asian-origin H5 Goose/Guangdong/1/96 (Gs/GD) lineage, highly pathogenic avian influenza viruses (HPAIV) had rarely caused high mortalities in domestic geese. In 2016/2017 European epidemics, H5N8 Gs/GD clade 2.3.4.4 Group B produced an unprecedented number of outbreaks in waterfowl holdings. In this study, the pathogenesis of H5N8 HPAIV in comparison with H7N1 HPAIV, and the role of domestic geese in the epidemiology of these viruses, were evaluated. Local and commercial geese (Anser anser var. domesticus) were intranasally inoculated with 10⁵ ELD₅₀ of A/goose/Spain/IA17CR02699/2017 (H5N8) or A/Chicken/Italy/5093/1999 (H7N1) and monitored daily during 15 days. H5N8 was highly virulent to domestic geese, reaching 100% mortality by 10 days post-infection. Systemic microscopic necrotizing lesions associated with widespread AIV-antigen were detected by IHC techniques, the central nervous system being the most severely affected. High viral loads, measured by qRT-PCR, were present in all samples collected: oral and cloacal swabs, plasma tissues, and moderate levels in pool water. Domestic geese were also susceptible to H7N1 infection, as demonstrated by seroconversion and detection of viral RNA in tissues and plasma in some geese, but all lacked clinical signs. Viral shedding was confirmed in only some geese and was restricted to the oral route, but levels were high and still detected at the end of the study. Overall, H7N1 presents a lower lethality and shedding than H5N8 in geese; however, the viral shedding indicates that these species could play a role in the epidemiology of Gs/GD and other lineages of HPAIVs. RESEARCH HIGHLIGHTS H5N8 Gs/GD clade 2.3.4.4 Group B is highly virulent to domestic geese. The severity of H5N8 is associated with multisystemic replication. H7N1 can infect domestic geese but is avirulent to this species. Domestic geese could play a role in the epidemiology of Gs/GD HPAIVs.

Adjuncts to local anesthetic wound infiltration for postoperative analgesia: a systematic review

Local anesthetics (LAs) are commonly infiltrated into surgical wounds for postsurgical analgesia. While many adjuncts to LA agents have been studied, it is unclear which adjuncts are most effective for co-infiltration to improve and prolong analgesia. We performed a systematic review on adjuncts (excluding epinephrine) to local infiltrative anesthesia to determine their analgesic efficacy and opioid-sparing properties. Multiple databases were searched up to December 2019 for randomized controlled trials (RCTs) and two reviewers independently performed title/abstract screening and full-text review. Inclusion criteria were (1) adult surgical patients and (2) adjunct and LA agents infiltration into the surgical wound or subcutaneous tissue for postoperative analgesia. To focus on wound infiltration, studies on intra-articular, peri-tonsillar, or fascial plane infiltration were excluded. The primary outcome was reduction in postoperative opioid requirement. Secondary outcomes were time-to-first analgesic use, postoperative pain score, and any reported adverse effects. We screened 6670 citations, reviewed 126 full-text articles, and included 89 RCTs. Adjuncts included opioids, non-steroidal anti-inflammatory drugs, steroids, alpha-2 agonists, ketamine, magnesium, neosaxitoxin, and methylene blue. Alpha-2 agonists have the most evidence to support their use as adjuncts to LA infiltration. Fentanyl, ketorolac, dexamethasone, magnesium and several other agents show potential as adjuncts but require more evidence. Most studies support the safety of these agents. Our findings suggest benefits of several adjuncts to local infiltrative anesthesia for postoperative analgesia. Further well-powered RCTs are needed to compare various infiltration regimens and agents.

Protocol registration

PROSPERO (CRD42018103851) (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=103851)

Incidence and etiology of postoperative neurological symptoms after peripheral nerve block: a retrospective cohort study

Background

Nerve injury from peripheral nerve block (PNB) is an uncommon but potentially serious complication. We present a retrospective cohort study to evaluate the incidence and etiology of new postoperative neurological symptoms after surgery and regional anesthesia.

Methods

We performed a retrospective cohort study of all PNBs performed on elective orthopedic and plastic surgical patients over 6 years (2011–2017). We collected patient and surgical data, results of neurophysiological and imaging tests, neurology and chronic pain consultations, etiology and outcome for patients with prolonged neurological symptoms (lasting ≥10 days).

Results

A total of 26 251 PNBs were performed in 19 219 patients during the study period. Transient postoperative neurological symptoms (<10 days) were reported by 14.4% (95% CI 13.1% to 15.7%) of patients who were reached by telephone follow-up. Prolonged postoperative neurological symptoms (≥10 days) were identified and investigated in 20 cases (1:1000, 95% CI 0.6 to 1.6). Of these 20 cases, three (0.2:1000, 95% CI 0.04 to 0.5) were deemed to be block related, seven related to surgical causes, three due to musculoskeletal causes or pain syndromes, one was suspected of having an inflammatory etiology and six remained of undetermined etiology. Of those who completed follow-up, 56% had full recovery of their symptoms with the remaining having partial recovery.

Conclusion

This retrospective review of 19 219 patients receiving PNBs for anesthesia or analgesia suggests that determining the etiology and causative factors of postoperative neurological symptoms is a complex, often challenging process that requires a multidisciplinary approach. We suggest a classification of cases based on the etiology. A most likely cause was identified in 70% of cases. This type of classification system can help broaden the differential diagnosis, help consider non-regional anesthesia and non-surgical causes and may be useful for clinical and research purposes.

Intertruncal approach to the supraclavicular brachial plexus, current controversies and technical update: a daring discourse

We propose a new approach to local anesthetic injection for the supraclavicular brachial plexus block: an intertruncal approach by which local anesthetic is deposited in the two adipose tissue planes between the upper and middle and the middle and lower trunks. We present sonographic and microscopic images to illustrate the relevant anatomy. This approach offers potential advantages over the ‘corner pocket’ technique in that it results in consistent local anesthetic spread to the three plexus trunks and the needle endpoint lies farther away from the pleural surface which is important for the prevention of pneumothorax. It also offers an advantage over the ‘intracluster’ approach as it purposefully avoids intraneural injection respecting the integrity of the epineurium of individual trunks. Comparative studies are required to confirm that these anatomic and technical advantages result in improved outcomes.

The effect of anesthetic technique on mortality and major morbidity after hip fracture surgery: a retrospective, propensity-score matched-pairs cohort study

Introduction

Spinal anesthesia (SA) has physiological benefits over general anesthesia (GA), but there is insufficient evidence regarding a mortality benefit. We performed a retrospective propensity score-matched cohort study to evaluate the impact of anesthetic technique on mortality and major morbidity in patients undergoing hip fracture surgery.

Materials and methods

Clinical, laboratory and outcome data were extracted from electronic databases for patients who underwent hip fracture surgery over a 13-year period at the University Health Network in Toronto, Ontario, Canada. The anesthetic technique was documented (SA or GA), and the primary outcome was 90-day mortality. Secondary outcomes included mortality at 30 and 60 days, hospital length of stay, pulmonary embolism (PE), major blood loss and major acute cardiac events. A propensity-score matched-pair analysis was performed following a non-parsimonious logistic regression model.

Results

Of the 2591 patients identified, 883 patients in the SA group were matched to patients in the GA group in a 1:1 ratio. There was a weak association between SA and lower 90-day mortality (risk ratio (RR) 0.74, 95% CI 0.52 to 0.96, 99% CI 0.48 to 1.00, p=0.037). SA was also associated with a lower incidence of both PE (1.3% vs 0.5%, p<0.001) and major blood loss (7.7% vs 4.8%, p<0.001) and a shorter hospital length of stay by about 2 days (median 11.9 vs 10 days, p=0.024). There was no difference in major cardiac events or mortality at 30 and 60 days.

Discussion

This propensity-score matched-pairs cohort study suggests that SA is weakly associated with a lower 90-day mortality following hip fracture surgery. SA was also associated with improved morbidity evidenced by a lower rate of PE and major blood loss and a shorter hospital length of stay. Given the retrospective nature of the study, these results are not proof of causality.

When fasted is not empty: a retrospective cohort study of gastric content in fasted surgical patients†

Background

Perioperative aspiration leads to significant morbidity and mortality. Point-of-care gastric ultrasound is an emerging tool to assess gastric content at the bedside.

Methods

We performed a retrospective cohort study of baseline gastric content on fasted elective surgical patients. The primary outcome was the incidence of full stomach (solid content or >1.5 ml kg−1 of clear fluid). Secondary outcomes included: gastric volume distribution (entire cohort, each antral grade); the association between gastric fullness, fasting intervals, and co-morbidities; anaesthetic management changes and incidence of aspiration.

Results

We identified 538 patients. Thirty-two patients (6.2%) presented with a full stomach. Nine of these (1.7%) had solid content and 23 (4.5%) had clear fluid >1.5 ml kg−1. An empty stomach was documented in 480 (89.8%) patients. The examination was inconclusive in the remaining 20 patients (5.0%). As expected, increasing antral grade was correlated with larger antral cross-sectional area and higher gastric volume (P<0.001). Of the 32 patients with a full stomach, only six had a documented risk factor for prolonged gastric emptying. The anaesthetic management was changed in all nine patients with solid content. No aspiration was reported.

Conclusions

This retrospective cohort study suggests that a small proportion of elective surgical patients may present with a full stomach despite the recommended duration of fasting. Further research is needed to establish the clinical implications of these findings in the elective setting. At present, the clinical role of gastric ultrasound continues to be for the evaluation of gastric contents to guide management when the risk of aspiration is uncertain or unknown.

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.

Pericapsular Nerve Group (PENG) Block for Hip Fracture

Fascia iliaca block or femoral nerve block is used frequently in hip fracture patients because of their opioid-sparing effects and reduction in opioid-related adverse effects. A recent anatomical study on hip innervation led to the identification of relevant landmarks to target the hip articular branches of femoral nerve and accessory obturator nerve. Using this information, we developed a novel ultrasound-guided approach for blockade of these articular branches to the hip, the PENG (PEricapsular Nerve Group) block. In this report, we describe the technique and its application in 5 consecutive patients.

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.

Real-time ultrasound-guided spinal anesthesia in patients with predicted difficult anatomy

BACKGROUND

There are limited reports of lumbar neuraxial blocks using real-time US in patients with predicted difficulties. We compared the number of attempts to perform spinal anesthesia using real-time US guidance versus landmark technique in patients meeting predefined criteria for difficult spinal anesthesia. We also compared procedure time, block success, patient satisfaction and difficulty scores between groups.

METHODS

Following institutional review board approval patients scheduled for total hip or knee arthroplasty with expected difficulty to perform spinal anesthesia were included. Number of attempts, block time, success rate, patient satisfaction and difficulty scores were recorded and we conducted the Kruskal-Wallis non-parametric test of difference between the groups.

RESULTS

Thirty-eight patients were enrolled and a total of 32 data sets was analyzed. For number of attempts, we observed no difference between the groups (P<0.83). The US group resulted in marginally higher time to block compared to the control (P<0.0653). The US group resulted in marginally higher satisfaction compared to the control group (P<0.09). The block success rate was 100% in both groups. Anesthesiologists rated the US group procedure more difficult than the control group (χ2=10.85, P<0.0010).

CONCLUSIONS

This trial suggests that real-time US guidance for spinal anesthesia in challenging patients in comparison to the controlled group was completed in longer time, with lower needle insertion attempts, and higher patient satisfaction scores but without statistically significant differences.