Noninvasive Ventilation for Preoxygenation during Emergency Intubation.

BACKGROUND: Among critically ill adults undergoing tracheal intubation, hypoxemia increases the risk of cardiac arrest and death. The effect of preoxygenation with noninvasive ventilation, as compared with preoxygenation with an oxygen mask, on the incidence of hypoxemia during tracheal intubation is uncertain. METHODS: In a multicenter, randomized trial conducted at 24 emergency departments and intensive care units in the United States, we randomly assigned critically ill adults (age, ≥18 years) undergoing tracheal intubation to receive preoxygenation with either noninvasive ventilation or an oxygen mask. The primary outcome was hypoxemia during intubation, defined by an oxygen saturation of less than 85% during the interval between induction of anesthesia and 2 minutes after tracheal intubation. RESULTS: Among the 1301 patients enrolled, hypoxemia occurred in 57 of 624 patients (9.1%) in the noninvasive-ventilation group and in 118 of 637 patients (18.5%) in the oxygen-mask group (difference, -9.4 percentage points; 95% confidence interval [CI], -13.2 to -5.6; P<0.001). Cardiac arrest occurred in 1 patient (0.2%) in the noninvasive-ventilation group and in 7 patients (1.1%) in the oxygen-mask group (difference, -0.9 percentage points; 95% CI, -1.8 to -0.1). Aspiration occurred in 6 patients (0.9%) in the noninvasive-ventilation group and in 9 patients (1.4%) in the oxygen-mask group (difference, -0.4 percentage points; 95% CI, -1.6 to 0.7). CONCLUSIONS: Among critically ill adults undergoing tracheal intubation, preoxygenation with noninvasive ventilation resulted in a lower incidence of hypoxemia during intubation than preoxygenation with an oxygen mask. (Funded by the U.S. Department of Defense; PREOXI ClinicalTrials.gov number, NCT05267652.).

Pulmonary Aspects of COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a respiratory virus that gains entry via angiotensin-converting enzyme 2 (ACE2) within airway epithelium. Patients exhibit a spectrum of respiratory symptoms from asymptomatic to respiratory failure. Patient factors including obesity, tobacco use, and black race are all associated with increased ACE2 expression and may contribute to increased complications. Consolidation and ground-glass opacities on chest imaging are typical but not specific for coronavirus disease 2019 (COVID-19). Venous thromboembolism occurs infrequently when prophylactic anticoagulation is provided. However, capillary microthrombosis is nearly ubiquitous, suggesting that it contributes to hypoxemia. Remdesivir and glucocorticoids may benefit some hospitalized patients. Many of those afflicted remain symptomatic two weeks following diagnosis and continue to require health care. Total lung capacity, diffusion capacity, and maximal oxygen consumption may be reduced for months in some survivors. Lung transplant offers chronically critically ill patients new hope, and this option may have increasing potential for outpatients with COVID-19-associated fibrosis.

Individualized Treatment Effects of Bougie versus Stylet for Tracheal Intubation in Critical Illness.

Rationale: A recent randomized trial found that using a bougie did not increase the incidence of successful intubation on first attempt in critically ill adults. The average effect of treatment in a trial population, however, may differ from effects for individuals. Objective: We hypothesized that application of a machine learning model to data from a clinical trial could estimate the effect of treatment (bougie vs. stylet) for individual patients based on their baseline characteristics ("individualized treatment effects"). Methods: This was a secondary analysis of the BOUGIE (Bougie or Stylet in Patients Undergoing Intubation Emergently) trial. A causal forest algorithm was used to model differences in outcome probabilities by randomized group assignment (bougie vs. stylet) for each patient in the first half of the trial (training cohort). This model was used to predict individualized treatment effects for each patient in the second half (validation cohort). Measurements and Main Results: Of 1,102 patients in the BOUGIE trial, 558 (50.6%) were the training cohort, and 544 (49.4%) were the validation cohort. In the validation cohort, individualized treatment effects predicted by the model significantly modified the effect of trial group assignment on the primary outcome (P value for interaction = 0.02; adjusted qini coefficient, 2.46). The most important model variables were difficult airway characteristics, body mass index, and Acute Physiology and Chronic Health Evaluation II score. Conclusions: In this hypothesis-generating secondary analysis of a randomized trial with no average treatment effect and no treatment effect in any prespecified subgroups, a causal forest machine learning algorithm identified patients who appeared to benefit from the use of a bougie over a stylet and from the use of a stylet over a bougie using complex interactions between baseline patient and operator characteristics.

Defining Successful Intubation on the First Attempt Using Both Laryngoscope and Endotracheal Tube Insertions: A Secondary Analysis of Clinical Trial Data.

STUDY OBJECTIVES: Successful intubation on the first attempt has historically been defined as successful placement of an endotracheal tube (ETT) using a single laryngoscope insertion. More recent studies have defined successful placement of an ETT using a single laryngoscope insertion followed by a single ETT insertion. We sought to estimate the prevalence of first-attempt success using these 2 definitions and estimate their associations with the duration of intubation and serious complications. METHODS: We performed a secondary analysis of data from 2 multicenter randomized trials of critically ill adults being intubated in the emergency department or ICU. We calculated the percent difference in successful intubations on the first attempt, median difference in the duration of intubation, and percent difference in the development of serious complications by definition. RESULTS: The study population included 1,863 patients. Successful intubation on the first attempt decreased by 4.9% (95% confidence interval 2.5% to 7.3%) when defined as 1 laryngoscope insertion followed by 1 ETT insertion (81.2%) compared with when defined as only 1 laryngoscope insertion (86.0%). When successful intubation with 1 laryngoscope and 1 ETT insertion was compared with 1 laryngoscope and multiple ETT insertions, the median duration of intubation decreased by 35.0 seconds (95% confidence interval 8.9 to 61.1 seconds). CONCLUSION: Defining successful intubation on the first attempt as placement of an ETT in the trachea using 1 laryngoscope and 1 ETT insertion identifies attempts with the shortest apneic time.

Laryngoscopy and Tracheal Intubation: Does Use of a Video Laryngoscope Facilitate Both Steps of the Procedure?

STUDY OBJECTIVE: To compare the effect of the use of a video laryngoscope versus a direct laryngoscope on each step of emergency intubation: laryngoscopy (step 1) and intubation of the trachea (step 2). METHODS: In a secondary observational analysis of data from 2 multicenter, randomized trials that enrolled critically ill adults undergoing tracheal intubation but did not control for laryngoscope type (video laryngoscope vs direct laryngoscope), we fit mixed-effects logistic regression models examining the 1) the association between laryngoscope type (video laryngoscope vs direct laryngoscope) and the Cormack-Lehane grade of view and 2) the interaction between grade of view, laryngoscope type (video laryngoscope vs direct laryngoscope), and the incidence of successful intubation on the first attempt. RESULTS: We analyzed 1,786 patients: 467 (26.2%) in the direct laryngoscope group and 1,319 (73.9%) in the video laryngoscope group. The use of a video laryngoscope was associated with an improved grade of view as compared with a direct laryngoscope (adjusted odds ratio for increasingly favorable grade of view 3.14, 95% confidence interval [CI] 2.47 to 3.99). Successful intubation on the first attempt occurred in 83.2% of patients in the video laryngoscope group and 72.2% of patients in the direct laryngoscope group (absolute difference 11.1%, 95% CI 6.5% to 15.6%). Video laryngoscope use modified the association between grade of view and successful intubation on the first attempt such that intubation on the first attempt was similar between video laryngoscope and direct laryngoscope at a grade 1 view and higher for video laryngoscope than direct laryngoscope at grade 2 to 4 views (P<.001 for interaction term). CONCLUSIONS: Among critically ill adults undergoing tracheal intubation, the use of a video laryngoscope was associated both with a better view of the vocal cords and with a higher probability of successfully intubating the trachea when the view of the vocal cords was incomplete in this observational analysis. However, a multicenter, randomized trial directly comparing the effect of a video laryngoscope with a direct laryngoscope on the grade of view, success, and complications is needed.

Ventilated Patients With COVID-19 Show Airflow Obstruction.

OBJECTIVE: Many patients with coronavirus disease 2019 (COVID-19) need mechanical ventilation secondary to acute respiratory distress syndrome. Information on the respiratory system mechanical characteristics of this disease is limited. The aim of this study is to describe the respiratory system mechanical properties of ventilated COVID-19 patients. DESIGN, SETTING, AND PATIENTS: Patients consecutively admitted to the medical intensive care unit at the University of Iowa Hospitals and Clinics in Iowa City, USA, from April 19 to May 1, 2020, were prospectively studied; final date of follow-up was May 1, 2020. MEASUREMENTS: At the time of first patient contact, ventilator information was collected including mode, settings, peak airway pressure, plateau pressure, and total positive end expiratory pressure. Indices of airflow resistance and respiratory system compliance were calculated and analyzed. MAIN RESULTS: The mean age of the patients was 58 years. 6 out of 12 (50%) patients were female. Of the 21 laboratory-confirmed COVID-19 patients on invasive mechanical ventilation, 9 patients who were actively breathing on the ventilator were excluded. All the patients included were on volume-control mode. Mean [±standard deviation] ventilator indices were: resistive pressure 19 [±4] cmH2O, airway resistance 20 [±4] cmH2O/L/s, and respiratory system static compliance 39 [±16] ml/cmH2O. These values are consistent with abnormally elevated resistance to airflow and reduced respiratory system compliance. Analysis of flow waveform graphics revealed a pattern consistent with airflow obstruction in all patients. CONCLUSIONS: Severe respiratory failure due to COVID-19 is regularly associated with airflow obstruction.

Effect of Use of a Bougie vs Endotracheal Tube With Stylet on Successful Intubation on the First Attempt Among Critically Ill Patients Undergoing Tracheal Intubation: A Randomized Clinical Trial.

Importance: For critically ill adults undergoing emergency tracheal intubation, failure to intubate the trachea on the first attempt occurs in up to 20% of cases and is associated with severe hypoxemia and cardiac arrest. Whether using a tracheal tube introducer ("bougie") increases the likelihood of successful intubation compared with using an endotracheal tube with stylet remains uncertain. Objective: To determine the effect of use of a bougie vs an endotracheal tube with stylet on successful intubation on the first attempt. Design, Setting, and Participants: The Bougie or Stylet in Patients Undergoing Intubation Emergently (BOUGIE) trial was a multicenter, randomized clinical trial among 1102 critically ill adults undergoing tracheal intubation in 7 emergency departments and 8 intensive care units in the US between April 29, 2019, and February 14, 2021; the date of final follow-up was March 14, 2021. Interventions: Patients were randomly assigned to use of a bougie (n = 556) or use of an endotracheal tube with stylet (n = 546). Main Outcomes and Measures: The primary outcome was successful intubation on the first attempt. The secondary outcome was the incidence of severe hypoxemia, defined as a peripheral oxygen saturation less than 80%. Results: Among 1106 patients randomized, 1102 (99.6%) completed the trial and were included in the primary analysis (median age, 58 years; 41.0% women). Successful intubation on the first attempt occurred in 447 patients (80.4%) in the bougie group and 453 patients (83.0%) in the stylet group (absolute risk difference, -2.6 percentage points [95% CI, -7.3 to 2.2]; P = .27). A total of 58 patients (11.0%) in the bougie group experienced severe hypoxemia, compared with 46 patients (8.8%) in the stylet group (absolute risk difference, 2.2 percentage points [95% CI, -1.6 to 6.0]). Esophageal intubation occurred in 4 patients (0.7%) in the bougie group and 5 patients (0.9%) in the stylet group, pneumothorax was present after intubation in 14 patients (2.5%) in the bougie group and 15 patients (2.7%) in the stylet group, and injury to oral, glottic, or thoracic structures occurred in 0 patients in the bougie group and 3 patients (0.5%) in the stylet group. Conclusions and Relevance: Among critically ill adults undergoing tracheal intubation, use of a bougie did not significantly increase the incidence of successful intubation on the first attempt compared with use of an endotracheal tube with stylet. Trial Registration: ClinicalTrials.gov Identifier: NCT03928925

Identification of a Novel Splice Variant Isoform of TREM-1 in Human Neutrophil Granules.

Triggering receptor expressed on myeloid cells-1 (TREM-1) is critical for inflammatory signal amplification. Humans have two forms of TREM-1: a membrane receptor, associated with the adaptor DAP12, and a soluble receptor detected at times of infection. The membrane receptor isoform acts synergistically with the TLR pathway to promote cytokine secretion and neutrophil migration, whereas the soluble receptor functions as a counterregulatory molecule. In multiple models of sepsis, exogenous administration of soluble forms of TREM-1 attenuates inflammation and markedly improves survival. Despite intense interest in soluble TREM-1, both as a clinical predictor of survival and as a therapeutic tool, the origin of native soluble TREM-1 remains controversial. Using human neutrophils, we identified a 15-kDa TREM-1 isoform in primary (azurophilic) and secondary (specific) granules. Mass spectrometric analysis, ELISA, and immunoblot confirm that the 15-kDa protein is a novel splice variant form of TREM-1 (TREM-1sv). Neutrophil stimulation with Pseudomonas aeruginosa, LPS, or PAM(3)Cys4 resulted in degranulation and release of TREM-1sv. The addition of exogenous TREM-1sv inhibited TREM-1 receptor-mediated proinflammatory cytokine production. Thus, these data reveal that TREM-1 isoforms simultaneously activate and inhibit inflammation via the canonical membrane TREM-1 molecule and this newly discovered granular isoform, TREM-1sv.

Antithrombotic Therapy for VTE Disease: Compendium and Review of CHEST Guidelines 2012-2021.

The American College of Chest Physicians (CHEST) Antithrombotic Therapy for Venous Thromboembolism Disease evidence-based guidelines are now updated in a more frequent, focused manner. Guidance statements from the most recent full guidelines and two subsequent updates have not been gathered into a single source. An international panel of experts with experience in prior antithrombotic therapy guideline development reviewed the 2012 CHEST antithrombotic therapy guidelines and its two subsequent updates. All guideline statements and their associated patient, intervention, comparator, and outcome questions were assembled. A modified Delphi process was used to select statements considered relevant to current clinical care. The panel further endorsed minor phrasing changes to match the standard language for guidance statements using the modified Grading of Recommendations, Assessment, Development, and Evaluations (ie, GRADE) format endorsed by the CHEST Guidelines Oversight Committee. The panel appended comments after statements deemed as relevant, including suggesting that statements be updated in future guidelines because of interval evidence. We include 58 guidance statements from prior versions of the antithrombotic therapy guidelines, with updated phrasing as needed to adhere to contemporary nomenclature. Statements were classified as strong or weak recommendations based on high-certainty, moderate-certainty, and low-certainty evidence using GRADE methodology. The panel suggested that five statements are no longer relevant to current practice. As CHEST continues to update guidance statements relevant to antithrombotic therapy for VTE disease, this article serves as a unified collection of currenrtly relevant statements from the preceding three guidelines. Suggestions have been made to update specific statements in future publications.

Techniques for the difficult airway.

PURPOSE OF REVIEW: Management of the difficult airway is associated with significant morbidity and mortality in critically ill patients. An increasing array of advanced airway tools are available, but appropriate selection and application in the ICU remains poorly defined. RECENT FINDINGS: Difficult airway incidence during emergent intubation is 10%, but complications of ICU airway management remain common. Training and equipment in many ICUs remain variable despite data that demonstrate that an 'intubation management bundle' and a systematic approach to teamwork and training can reduce life-threatening airway complications. A protocol employing an extraglottic airway (EGA) early in cases of inadequate ventilation has been associated with no episodes of prolonged hypoxemia in 12 225 consecutive intubations. Direct laryngoscopy with gum elastic bougie is the most commonly employed method to manage emergent difficult airways, and videolaryngoscopes also provide greater glottic visualization and a high rate of intubation success in patients with difficult airway risk factors or a failed airway. SUMMARY: A systematic approach to intubation that emphasizes planning and teamwork can reduce intubation complications. Early use of an EGA or cricothyroidotomy may reduce complications when oxygenation is inadequate. Use of a gum elastic bougie or indirect optical device is also associated with a high rate of intubation success when oxygenation permits.

Prophylactic Administration of Vasopressors Prior to Emergency Intubation in Critically Ill Patients: A Secondary Analysis of Two Multicenter Clinical Trials.

Hypotension affects approximately 40% of critically ill patients undergoing emergency intubation and is associated with an increased risk of death. The objective of this study was to examine the association between prophylactic vasopressor administration and the incidence of peri-intubation hypotension and other clinical outcomes. DESIGN: A secondary analysis of two multicenter randomized clinical trials. The clinical effect of prophylactic vasopressor administration was estimated using a one-to-one propensity-matched cohort of patients with and without prophylactic vasopressors. SETTING: Seven emergency departments and 17 ICUs across the United States. PATIENTS: One thousand seven hundred ninety-eight critically ill patients who underwent emergency intubation at the study sites between February 1, 2019, and May 24, 2021. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was peri-intubation hypotension defined as a systolic blood pressure less than 90 mm Hg occurring between induction and 2 minutes after tracheal intubation. A total of 187 patients (10%) received prophylactic vasopressors prior to intubation. Compared with patients who did not receive prophylactic vasopressors, those who did were older, had higher Acute Physiology and Chronic Health Evaluation II scores, were more likely to have a diagnosis of sepsis, had lower pre-induction systolic blood pressures, and were more likely to be on continuous vasopressor infusions prior to intubation. In our propensity-matched cohort, prophylactic vasopressor administration was not associated with reduced risk of peri-intubation hypotension (41% vs 32%; p = 0.08) or change in systolic blood pressure from baseline (-12 vs -11 mm Hg; p = 0.66). CONCLUSIONS: The administration of prophylactic vasopressors was not associated with a lower incidence of peri-intubation hypotension in our propensity-matched analysis. To address potential residual confounding, randomized clinical trials should examine the effect of prophylactic vasopressor administration on peri-intubation outcomes.

Patient-Ventilator Synchrony.

Patient-ventilator asynchrony develops when the ventilator output does not match the efforts of the patient and contributes to excess work of breathing, lung injury, and mortality. Asynchronies are categorized as trigger (breath initiation), flow (delivery of the breath), and cycle (transition from inspiration to expiration). Clinicians should be skilled at ventilator waveform analysis to detect patient-ventilator asynchronies and make informed ventilator adjustments. Ventilator overdrive suppresses respiratory drive and reduces asynchrony, while other adjustments specific to the asynchrony are also useful.

Thromboprophylaxis in Patients With COVID-19: A Brief Update to the CHEST Guideline and Expert Panel Report.

BACKGROUND: Patients hospitalized with COVID-19 often exhibit markers of a hypercoagulable state and have an increased incidence of VTE. In response, CHEST issued rapid clinical guidance regarding prevention of VTE. Over the past 18 months the quality of the evidence has improved. We thus sought to incorporate this evidence and update our recommendations as necessary. STUDY DESIGN AND METHODS: This update focuses on the optimal approach to thromboprophylaxis in hospitalized patients. The original questions were used to guide the search, using MEDLINE via PubMed. Eight randomized controlled trials and one observational study were included. Meta-analysis, using a random effects model, was performed. The panel created summaries using the GRADE Evidence-to-Decision framework. Updated guidance statements were drafted, and a modified Delphi approach was used to obtain consensus. RESULTS: We provide separate guidance statements for VTE prevention for hospitalized patients with acute (moderate) illness and critically ill patients in the ICU. However, we divided each original question and resulting recommendation into two questions: standard prophylaxis vs therapeutic (or escalated dose) prophylaxis and standard prophylaxis vs intermediate dose prophylaxis. This led to a change in one recommendation, and an upgrading of three additional recommendations based upon higher quality evidence. CONCLUSIONS: Advances in care for patients with COVID-19 have improved overall outcomes. Despite this, rates of VTE in these patients remain elevated. Critically ill patients should receive standard thromboprophylaxis for VTE, and moderately ill patients with a low bleeding risk might benefit from therapeutic heparin. We see no role for intermediate dose thromboprophylaxis in either setting.

Insulin-like growth factor-1 levels contribute to the development of bacterial translocation in sepsis.

RATIONALE: Many lines of evidence point toward the gastrointestinal (GI) tract in the pathophysiology of organ dysfunction in sepsis. Splanchnic hypoperfusion during sepsis leads to enterocyte apoptosis, diminished barrier function, and release of bacterial products. Sepsis lowers levels of insulin-like growth factor (IGF)-1, a known antiapoptotic factor. We recently demonstrated that treatment with IGF-1 is protective in murine sepsis. OBJECTIVES: We hypothesize that decreased IGF-1 levels in sepsis contributes to the development of bacterial translocation. METHODS: Sepsis was induced in C57BL/6 mice via intratracheal instillation of Pseudomonas aeruginosa. Human subjects with sepsis were enrolled if they had a documented positive blood culture with a nonenteric organism. Bacterial translocation was measured in serum by quantitative real-time polymerase chain reaction with primers specific for enteric bacteria. Serum IGF-1 was measured by ELISA. Apoptosis of the GI epithelium was assessed via immunohistochemistry. MEASUREMENTS AND MAIN RESULTS: We found that mice with severe sepsis had evidence of bacterial translocation by 24 hours. Enteric bacterial load correlated inversely with levels of serum IGF-1. If we treated mice with IGF-1, bacterial translocation was significantly decreased. In addition, we found increased GI epithelial cell apoptosis after sepsis, which was significantly decreased after IGF-1 treatment. Human subjects with nonenteric sepsis developed progressive enteric bacteremia over 3 days. The degree of enteric bacteremia correlated inversely with serum IGF-1 levels. CONCLUSIONS: These data support the hypothesis that sepsis-induced reductions in IGF-1 levels contribute to the development of bacterial translocation in both a murine model and human subjects.

Maintaining Mobility in a Patient Who Is Pregnant and Has COVID-19 Requiring Extracorporeal Membrane Oxygenation: A Case Report.

OBJECTIVE: Mobilization while receiving life support interventions, including mechanical ventilation and extracorporeal membrane oxygenation (ECMO), is a recommended intensive care unit (ICU) intervention to maintain physical function. The purpose of this case report is to describe a novel approach to implementing early mobility interventions for a patient who was pregnant and receiving ECMO while continuing necessary infectious disease precautions because of diagnosed coronavirus disease-19 (COVID-19). METHODS: A 27-year-old woman who was pregnant was admitted to the ICU with COVID-19 and rapidly developed acute respiratory failure requiring 9 days of ECMO support. After a physical therapist consultation, the patient was standing at the bedside by hospital day 5 and ambulating by hospital day 9. RESULTS: The patient safely participated in physical therapy during ICU admission and was discharged to home with outpatient physical therapy follow-up after 14 days of hospitalization. CONCLUSION: Early mobility is feasible during ECMO with COVID-19, and active participation in physical therapy, including in-room ambulation, may facilitate discharge to home. Innovative strategies to facilitate routine activity in a patient who is critically ill with COVID-19 require an established and highly trained team with a focus on maintaining function. IMPACT: Early mobility while intubated, on ECMO, and infected with COVID-19 is feasible while adhering to infectious disease precautions when it is performed by an experienced interdisciplinary team.

Survival of Pregnant Coronavirus Patient on Extracorporeal Membrane Oxygenation.

A 27-year-old woman presented at 23 weeks' 6 days' gestation who tested positive for the coronavirus disease 2019 (COVID-19). Despite mechanical ventilation and paralysis, she remained hypoxic and was emergently cannulated for veno-venous extracorporeal membrane oxygenation (VV-ECMO). The patient ambulated while intubated and on VV-ECMO. She was decannulated and extubated. An ultrasound demonstrated an appropriately grown fetus without abnormalities. She was discharged to home and gave birth to a healthy baby girl at 39 weeks' gestation. Using VV-ECMO, this patient and her fetus survived acute hypoxemic respiratory failure due to COVID-19.

Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline and Expert Panel Report.

BACKGROUND: This is the 2nd update to the 9th edition of these guidelines. We provide recommendations on 17 PICO (Population, Intervention, Comparator, Outcome) questions, four of which have not been addressed previously. METHODS: We generate strong and weak recommendations based on high-, moderate-, and low-certainty evidence, using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) methodology. RESULTS: The panel generated 29 guidance statements, 13 of which are graded as strong recommendations, covering aspects of antithrombotic management of VTE from initial management through secondary prevention and risk reduction of postthrombotic syndrome. Four new guidance statements have been added that did not appear in the 9th edition (2012) or 1st update (2016). Eight statements have been substantially modified from the 1st update. CONCLUSION: New evidence has emerged since 2016 that further informs the standard of care for patients with VTE. Substantial uncertainty remains regarding important management questions, particularly in limited disease and special patient populations.

Executive Summary: Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline and Expert Panel Report.

BACKGROUND: This is the 2nd update to the 9th edition of these guidelines. We provide recommendations on 17 PICO (Population, Intervention, Comparator, Outcome) questions, four of which have not been addressed previously. METHODS: We generate strong and weak recommendations based on high-, moderate-, and low-certainty evidence, using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) methodology. RESULTS: The panel generated 29 guidance statements, 13 of which are graded as strong recommendations, covering aspects of antithrombotic management of VTE from initial management through secondary prevention and risk reduction of postthrombotic syndrome. Four new guidance statements have been added that did not appear in the 9th edition (2012) or 1st update (2016). Eight statements have been substantially modified from the 1st update. CONCLUSION: New evidence has emerged since 2016 that further informs the standard of care for patients with VTE. Substantial uncertainty remains regarding important management questions, particularly in limited disease and special patient populations.

BOugie or stylet in patients UnderGoing Intubation Emergently (BOUGIE): protocol and statistical analysis plan for a randomised clinical trial.

INTRODUCTION: Intubation-related complications are less frequent when intubation is successful on the first attempt. The rate of first attempt success in the emergency department (ED) and intensive care unit (ICU) is typically less than 90%. The bougie, a semirigid introducer that can be placed into the trachea to facilitate a Seldinger-like technique of tracheal intubation and is typically reserved for difficult or failed intubations, might improve first attempt success. Evidence supporting its use, however, is from a single academic ED with frequent bougie use. Validation of these findings is needed before widespread implementation. METHODS AND ANALYSIS: The BOugie or stylet in patients Undergoing Intubation Emergently trial is a prospective, multicentre, non-blinded randomised trial being conducted in six EDs and six ICUs in the USA. The trial plans to enrol 1106 critically ill adults undergoing orotracheal intubation. Eligible patients are randomised 1:1 for the use of a bougie or use of an endotracheal tube with stylet for the first intubation attempt. The primary outcome is successful intubation on the first attempt. The secondary outcome is severe hypoxaemia, defined as an oxygen saturation less than 80% between induction until 2 min after completion of intubation. Enrolment began on 29 April 2019 and is expected to be completed in 2021. ETHICS AND DISSEMINATION: The trial protocol was approved with waiver of informed consent by the Central Institutional Review Board at Vanderbilt University Medical Center or the local institutional review board at an enrolling site. The results will be submitted for publication in a peer-reviewed journal and presented at scientific conferences. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT03928925).

Renin-angiotensin system activation correlates with microvascular dysfunction in a prospective cohort study of clinical sepsis.

INTRODUCTION: Microvascular dysregulation characterized by hyporesponsive vessels and heterogeneous bloodflow is implicated in the pathogenesis of organ failure in sepsis. The renin-angiotensin system (RAS) affects the microvasculature, yet the relationships between RAS and organ injury in clinical sepsis remain unclear. We tested our hypothesis that systemic RAS mediators are associated with dysregulation of the microvasculature and with organ failure in clinical severe sepsis. METHODS: We studied 30 subjects with severe sepsis, and 10 healthy control subjects. Plasma was analyzed for plasma renin activity (PRA) and angiotensin II concentration (Ang II). Using near-infrared spectroscopy, we measured the rate of increase in the oxygen saturation of thenar microvascular hemoglobin after five minutes of induced forearm ischemia. In so doing, we assessed bulk microvascular hemoglobin influx to the tissue during reactive hyperemia. We studied all subjects 24 hours after the development of organ failure. We studied a subset of 12 subjects at an additional timepoint, eight hours after recognition of organ failure (early sepsis). RESULTS: After 24 hours of resuscitation to clinically-defined endpoints of preload and arterial pressure, Ang II and PRA were elevated in septic subjects and the degree of elevation correlated negatively with the rate of microvascular reoxygenation during reactive hyperemia. Early RAS mediators correlated with microvascular dysfunction. Early Ang II also correlated with the extent of organ failure realized during the first day of sepsis. CONCLUSIONS: RAS is activated in clinical severe sepsis. Systemic RAS mediators correlate with measures of microvascular dysregulation and with organ failure.