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3.
Crit Care Med ; 48(3): e173-e191, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32058387

RESUMO

OBJECTIVES: To develop evidence-based recommendations for clinicians caring for adults with acute or acute on chronic liver failure in the ICU. DESIGN: The guideline panel comprised 29 members with expertise in aspects of care of the critically ill patient with liver failure and/or methodology. The Society of Critical Care Medicine standard operating procedures manual and conflict-of-interest policy were followed throughout. Teleconferences and electronic-based discussion among the panel, as well as within subgroups, served as an integral part of the guideline development. SETTING: The panel was divided into nine subgroups: cardiovascular, hematology, pulmonary, renal, endocrine and nutrition, gastrointestinal, infection, perioperative, and neurology. INTERVENTIONS: We developed and selected population, intervention, comparison, and outcomes questions according to importance to patients and practicing clinicians. For each population, intervention, comparison, and outcomes question, we conducted a systematic review aiming to identify the best available evidence, statistically summarized the evidence whenever applicable, and assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. We used the evidence to decision framework to facilitate recommendations formulation as strong or conditional. We followed strict criteria to formulate best practice statements. MEASUREMENTS AND MAIN RESULTS: In this article, we report 29 recommendations (from 30 population, intervention, comparison, and outcomes questions) on the management acute or acute on chronic liver failure in the ICU, related to five groups (cardiovascular, hematology, pulmonary, renal, and endocrine). Overall, six were strong recommendations, 19 were conditional recommendations, four were best-practice statements, and in two instances, the panel did not issue a recommendation due to insufficient evidence. CONCLUSIONS: Multidisciplinary international experts were able to formulate evidence-based recommendations for the management acute or acute on chronic liver failure in the ICU, acknowledging that most recommendations were based on low-quality indirect evidence.

4.
Prehosp Emerg Care ; : 1-8, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31971839

RESUMO

Objective: Many sepsis patients receive initial care from prehospital Emergency Medical Services (EMS). While earlier sepsis care improves outcomes, the characteristics, care and outcomes of those treated by EMS versus those arriving directly to an emergency department (ED) are currently not detailed. We sought to determine differences in hospital presentation, course and outcomes between EMS and non-EMS patients enrolled in the Protocolized Care of Early Septic Shock (ProCESS) trial. Methods: We performed a secondary analysis of ProCESS, which studied ED patients with septic shock. EMS care was the primary exposure. We determined differences in demographics, clinical features, interventions and hospital course between EMS and non-EMS patients. Using mixed models, we determined the association between EMS care and 60-day mortality. Results: Among 1,341 patients, 826 (61.6%) received initial EMS care. EMS patients were older, more likely to be black (OR 1.49, 95% CI 1.14-1.95) or nursing home residents (5.57, 3.61-8.60), and more likely to have chronic respiratory disease (1.36, 1.04-1.78), cerebral vascular disease (1.56; 1.04-2.33), peripheral vascular disease (2.02; 1.29-3.16), and dementia (3.53; 2.04-6.10). EMS patients were more likely to present with coma (4.48; 2.53-7.96) or elevated lactate (1.30; 1.04-1.63), and to receive mechanical ventilation in the ED (7.16; 4.34-11.79). There were no differences in infection source or total intravenous fluids. Initial differences in vasopressor use (1.66; 1.22-2.26) resolved at 6 hours (1.18; 0.94-1.47). Initial differences in APACHE II (EMS 21.8 vs. non-EMS 19.0) narrowed by 48 hours (17.9 vs. 16.3, [EMS X time] interaction p = 0.003). Although EMS patients exhibited higher 60-day mortality, after adjustment for confounders, this association was not significant (1.09, 95% CI: 0.78-1.55). Conclusions: While EMS sepsis patients presented with worse chronic, nonmodifiable characteristics and higher acuity than non-EMS patients, differences in acuity narrowed after initial hospital care. Despite having higher illness burden, EMS patients did not have worse adjusted short-term mortality.

6.
Intensive Care Med ; 46(1): 1-16, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31588983

RESUMO

PURPOSE: Acute liver failure (ALF) and acute on chronic liver failure (ACLF) are associated with significant mortality and morbidity. Extracorporeal liver support (ECLS) devices have been used as a bridge to liver transplant; however, the efficacy and safety of ECLS are unclear. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to examine the efficacy and safety of ECLS in liver failure. METHODS: We searched MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials from inception through March 13, 2019. RCTs comparing ECLS to usual care in ALF or ACLF were included. We used the Grading of Recommendations Assessment, Development and Evaluation approach to assess the certainty of the evidence. RESULTS: We identified 25 RCTs (1796 patients). ECLS use was associated with reduction in mortality (RR 0.84; 95% CI 0.74, 0.96, moderate certainty) and improvement in hepatic encephalopathy (HE) (RR 0.71; 95% CI 0.60, 0.84, low certainty) in patients with ALF or ACLF. The effect of ECLS on hypotension (RR 1.46; 95% CI 0.98, 2.2, low certainty), bleeding (RR 1.21; 95% CI 0.88, 1.66, moderate certainty), thrombocytopenia (RR 1.62; 95% CI 1.0, 2.64, very low certainty) and line infection (RR 1.92; 95% CI 0.11, 33.44, low certainty) was uncertain. CONCLUSIONS: ECLS may reduce mortality and improve HE in patients with ALF and ACLF. The effect on other outcomes is uncertain. However, the evidence is limited by risk of bias and imprecision, and larger trials are needed to better determine the effect of ECLS on patient-important outcomes.

7.
Am J Cardiol ; 125(5): 777-782, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31883682

RESUMO

Low systolic blood pressure (SBP) is associated with increased mortality and heart failure in patients with left ventricular dysfunction. Data on the relation between SBP measured following cardiac resynchronization therapy implantation and subsequent clinical events are limited. We hypothesized that assessment of systolic blood pressure at 12 months after cardiac resynchronization therapy can be used to identify patients with increased risk for adverse cardiovascular outcomes. The study population comprised 1000 patients who underwent cardiac resynchronization therapy implantation in MADIT-CRT. Outcomes were compared between patients with low (<110 mm Hg) and preserved SBP (≥110 mm Hg) at 1 year. At 1 year following cardiac resynchronization therapy, 800 patients (80%) had preserved systolic blood pressure. Kaplan-Meier survival analysis showed that the rate of heart failure or death during subsequent follow-up was significantly higher among patients with low SBP as compared with a preserved SBP at 12 months (2-year rates: 20% vs 12%, respectively; log-rank p value = 0.009 for the overall difference during follow-up). Consistently, multivariate analysis showed that patients with preserved SBP at 1 year had a 29% lower risk of HF or death when compared with the low SBP group (p = 0.024). The association between SBP measured following cardiac resynchronization therapy implantation and subsequent clinical events was more pronounced among patients with nonischemic cardiomyopathy (p value for SBP-by-HF etiology interaction = 0.034). In conclusion, assessment of SBP following cardiac resynchronization therapy can be used for improved long-term risk stratification in this population.

8.
Crit Care Clin ; 36(1): 23-40, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31733680

RESUMO

Procalcitonin is a biomarker that is generally elevated in bacterial infections. This review describes a conceptual framework for biomarkers using lessons from the history of troponin, applies this framework to procalcitonin with a review of observational studies and randomized trials in and out of the intensive care unit, and concludes with clinical recommendations and thoughts on how to test a test.

9.
BMJ Open ; 9(12): e034406, 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31852712

RESUMO

INTRODUCTION: Septic shock is a common and highly morbid condition. To date, there is no specific therapy proven to attenuate organ injury in septic shock. Recent studies have suggested a role for the combination of ascorbic acid, corticosteroids and thiamine, although randomised data are lacking. METHODS AND ANALYSIS: The Ascorbic Acid, Corticosteroids, and Thiamine in Sepsis trial is a multi-centre, double-blind, randomised, placebo-controlled clinical trial that aims to determine the impact of ascorbic acid, corticosteroids and thiamine versus placebo on organ injury and mortality in patients with septic shock. Patients are randomised to receive 1500 mg of ascorbic acid, 100 mg of thiamine and 50 mg of hydrocortisone parenterally versus matching placebo every 6 hours for 4 days. Clinical and laboratory data are collected at the time of study enrolment, at 24, 72 and 120 hours. The primary end-point for the trial is change in the Sequential Organ Failure Assessment score between enrolment and 72 hours. Additional key secondary outcomes include the incidence of renal failure and 30-day mortality. ETHICS AND DISSEMINATION: The study was approved by the international review board of each participating study site. Study findings will be disseminated through peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER: The trial is registered on clinicaltrials.gov (NCT03389555). It was posted on 3 January 2018.

10.
Eur Heart J ; 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31713598

RESUMO

Multiple randomized multicentre clinical trials have established the role of the implantable cardioverter-defibrillator (ICD) as the mainstay in the treatment of ventricular tachyarrhythmias and sudden cardiac death (SCD) prevention. These trials have focused mainly on heart failure patients with advanced left ventricular dysfunction and were mostly conducted two decades ago, whereas a more recent trial has provided conflicting results. Therefore, much remains to be determined on how best to balance the identification of patients at high risk of SCD together with who would benefit most from ICD implantation in a contemporary setting. Implantable cardioverter-defibrillators have also evolved from the simple, defibrillation-only devices implanted surgically to more advanced technologies of multi-chamber devices, with physiologic bradycardic pacing, including cardiac resynchronization therapy, atrial and ventricular therapeutic pacing algorithms, and subcutaneous ICDs. These multiple options necessitate individualized approach to device selection and programming. This review will focus on the current knowledge on selection of patients for ICD treatment, device selection and programming, and future directions of implantable device therapy for SCD prevention.

12.
Obesity (Silver Spring) ; 27(10): 1711-1719, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31544344

RESUMO

OBJECTIVE: The aim of this study was to compare national estimates of self-reported and measured height and weight, BMI, and obesity prevalence among adults from US surveys. METHODS: Self-reported height and weight data came from the National Health and Nutrition Examination Survey (NHANES), the National Health Interview Survey, and the Behavioral Risk Factor Surveillance System for the years 1999 to 2016. Measured height and weight data were available from NHANES. BMI was calculated from height and weight; obesity was defined as BMI ≥ 30. RESULTS: In all three surveys, mean self-reported height was higher than mean measured height in NHANES for both men and women. Mean BMI from self-reported data was lower than mean BMI from measured data across all surveys. For women, mean self-reported weight, BMI, and obesity prevalence in the National Health Interview Survey and Behavioral Risk Factor Surveillance System were lower than self-report in NHANES. The distribution of BMI was narrower for self-reported than for measured data, leading to lower estimates of obesity prevalence. CONCLUSIONS: Self-reported height, weight, BMI, and obesity prevalence were not identical across the three surveys, particularly for women. Patterns of misreporting of height and weight and their effects on BMI and obesity prevalence are complex.

13.
Artigo em Inglês | MEDLINE | ID: mdl-31148210

RESUMO

BACKGROUND: Sepsis is characterized by life-threatening organ dysfunction caused by a dysregulated host response to infection and affects over 1 million Americans annually. Loss of glycemic control in sepsis is associated with increased morbidity and mortality, and novel approaches are needed to promote euglycemia and improve outcomes in sepsis. Recent studies from our laboratory demonstrate that early low-level enteral dextrose infusion in septic mice attenuates the systemic inflammatory response and improves glycemic control by inducing intestine-derived incretin hormone secretion. AIM: The aim of the Study of Early Enteral Dextrose in Sepsis (SEEDS) is to test the effect of a 24-hour enteral dextrose infusion in critically ill septic patients as a therapeutic agent to decrease systemic inflammation and promote euglycemia. METHODS: SEEDS is a single-center, double-blind, randomized, controlled trial that will enroll 60 septic patients admitted to the intensive care units at the University of Pittsburgh Medical Center Health System in Pittsburgh. Participants will be randomized 1:1 to receive enteral dextrose (n = 30) or water (placebo, n = 30) infusion for 24 hours. The primary outcome is the circulating interleukin-6 level measured after the 24-hour infusion compared between dextrose and placebo groups. Secondary outcomes include postinfusion circulating insulin, incretin, and other proinflammatory cytokine levels, as well as incidence of hyperglycemia and hypoglycemia during the infusion period. DISCUSSION: This trial will characterize the effects of early enteral dextrose on endogenous endocrine pathways and the systemic inflammatory response in sepsis. The results of this trial will inform future larger interventional studies of early enteral nutrients in critically ill patients with sepsis.

14.
JAMA ; 321(20): 2003-2017, 2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-31104070

RESUMO

Importance: Sepsis is a heterogeneous syndrome. Identification of distinct clinical phenotypes may allow more precise therapy and improve care. Objective: To derive sepsis phenotypes from clinical data, determine their reproducibility and correlation with host-response biomarkers and clinical outcomes, and assess the potential causal relationship with results from randomized clinical trials (RCTs). Design, Settings, and Participants: Retrospective analysis of data sets using statistical, machine learning, and simulation tools. Phenotypes were derived among 20 189 total patients (16 552 unique patients) who met Sepsis-3 criteria within 6 hours of hospital presentation at 12 Pennsylvania hospitals (2010-2012) using consensus k means clustering applied to 29 variables. Reproducibility and correlation with biological parameters and clinical outcomes were assessed in a second database (2013-2014; n = 43 086 total patients and n = 31 160 unique patients), in a prospective cohort study of sepsis due to pneumonia (n = 583), and in 3 sepsis RCTs (n = 4737). Exposures: All clinical and laboratory variables in the electronic health record. Main Outcomes and Measures: Derived phenotype (α, ß, γ, and δ) frequency, host-response biomarkers, 28-day and 365-day mortality, and RCT simulation outputs. Results: The derivation cohort included 20 189 patients with sepsis (mean age, 64 [SD, 17] years; 10 022 [50%] male; mean maximum 24-hour Sequential Organ Failure Assessment [SOFA] score, 3.9 [SD, 2.4]). The validation cohort included 43 086 patients (mean age, 67 [SD, 17] years; 21 993 [51%] male; mean maximum 24-hour SOFA score, 3.6 [SD, 2.0]). Of the 4 derived phenotypes, the α phenotype was the most common (n = 6625; 33%) and included patients with the lowest administration of a vasopressor; in the ß phenotype (n = 5512; 27%), patients were older and had more chronic illness and renal dysfunction; in the γ phenotype (n = 5385; 27%), patients had more inflammation and pulmonary dysfunction; and in the δ phenotype (n = 2667; 13%), patients had more liver dysfunction and septic shock. Phenotype distributions were similar in the validation cohort. There were consistent differences in biomarker patterns by phenotype. In the derivation cohort, cumulative 28-day mortality was 287 deaths of 5691 unique patients (5%) for the α phenotype; 561 of 4420 (13%) for the ß phenotype; 1031 of 4318 (24%) for the γ phenotype; and 897 of 2223 (40%) for the δ phenotype. Across all cohorts and trials, 28-day and 365-day mortality were highest among the δ phenotype vs the other 3 phenotypes (P < .001). In simulation models, the proportion of RCTs reporting benefit, harm, or no effect changed considerably (eg, varying the phenotype frequencies within an RCT of early goal-directed therapy changed the results from >33% chance of benefit to >60% chance of harm). Conclusions and Relevance: In this retrospective analysis of data sets from patients with sepsis, 4 clinical phenotypes were identified that correlated with host-response patterns and clinical outcomes, and simulations suggested these phenotypes may help in understanding heterogeneity of treatment effects. Further research is needed to determine the utility of these phenotypes in clinical care and for informing trial design and interpretation.


Assuntos
Sepse/classificação , Algoritmos , Biomarcadores/sangue , Análise por Conglomerados , Conjuntos de Dados como Assunto , Mortalidade Hospitalar , Humanos , Aprendizado de Máquina , Escores de Disfunção Orgânica , Fenótipo , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sepse/mortalidade , Sepse/terapia
15.
Semin Respir Crit Care Med ; 40(1): 101-113, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-31060092

RESUMO

The pharmacology and history of neuromuscular blockade in clinical care are complex, with multiple theoretical and observed potential benefits and potential harms. Past studies raised concern for long-term paresis, but more recent studies have not found evidence for harm, possibly due to changes in background care, neuromuscular blocking agent, and duration of blockade. Current use is highly variable, likely due to limited evidence for efficacy beyond short-term physiologic improvement and lingering concerns for harm. A recently completed large multicenter trial will provide further information on the role of pharmacologic paralysis in acute respiratory distress syndrome.

16.
N Engl J Med ; 380(21): 1997-2008, 2019 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-31112383

RESUMO

BACKGROUND: The benefits of early continuous neuromuscular blockade in patients with acute respiratory distress syndrome (ARDS) who are receiving mechanical ventilation remain unclear. METHODS: We randomly assigned patients with moderate-to-severe ARDS (defined by a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen of <150 mm Hg with a positive end-expiratory pressure [PEEP] of ≥8 cm of water) to a 48-hour continuous infusion of cisatracurium with concomitant deep sedation (intervention group) or to a usual-care approach without routine neuromuscular blockade and with lighter sedation targets (control group). The same mechanical-ventilation strategies were used in both groups, including a strategy involving a high PEEP. The primary end point was in-hospital death from any cause at 90 days. RESULTS: The trial was stopped at the second interim analysis for futility. We enrolled 1006 patients early after the onset of moderate-to-severe ARDS (median, 7.6 hours after onset). During the first 48 hours after randomization, 488 of the 501 patients (97.4%) in the intervention group started a continuous infusion of cisatracurium (median duration of infusion, 47.8 hours; median dose, 1807 mg), and 86 of the 505 patients (17.0%) in the control group received a neuromuscular blocking agent (median dose, 38 mg). At 90 days, 213 patients (42.5%) in the intervention group and 216 (42.8%) in the control group had died before hospital discharge (between-group difference, -0.3 percentage points; 95% confidence interval, -6.4 to 5.9; P = 0.93). While in the hospital, patients in the intervention group were less physically active and had more adverse cardiovascular events than patients in the control group. There were no consistent between-group differences in end points assessed at 3, 6, and 12 months. CONCLUSIONS: Among patients with moderate-to-severe ARDS who were treated with a strategy involving a high PEEP, there was no significant difference in mortality at 90 days between patients who received an early and continuous cisatracurium infusion and those who were treated with a usual-care approach with lighter sedation targets. (Funded by the National Heart, Lung, and Blood Institute; ROSE ClinicalTrials.gov number, NCT02509078.).


Assuntos
Atracúrio/análogos & derivados , Bloqueadores Neuromusculares/uso terapêutico , Respiração com Pressão Positiva , Síndrome do Desconforto Respiratório do Adulto/tratamento farmacológico , Adulto , Idoso , Atracúrio/efeitos adversos , Atracúrio/uso terapêutico , Terapia Combinada , Sedação Consciente , Feminino , Mortalidade Hospitalar , Humanos , Masculino , Pessoa de Meia-Idade , Bloqueio Neuromuscular , Bloqueadores Neuromusculares/efeitos adversos , Síndrome do Desconforto Respiratório do Adulto/mortalidade , Síndrome do Desconforto Respiratório do Adulto/terapia , Falha de Tratamento
17.
Cardiovasc Eng Technol ; 10(2): 354-366, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30989616

RESUMO

PURPOSE: Multi-polar diagnostic catheters are used to construct the 3D electro-anatomic mapping of the atrium during atrial fibrillation (AF) ablation procedures; however, it remains unclear how to use the electrograms recorded by these catheters to locate AF-driving sites known as focal and rotor source types. The purpose of this study is to present the first algorithm to iteratively navigate a circular multi-polar catheter to locate AF focal and rotor sources without the need to map the entire atria. METHODS: Starting from an initial location, the algorithm, which was blinded to the location and type of the AF source, iteratively advanced a Lasso catheter based on its electrogram characteristics. The algorithm stopped the catheter when it located of an AF source and identified the type. The efficiency of the algorithm is validated using a set of simulated focal and rotor-driven arrhythmias in fibrotic human 2D and 3D atrial tissue. RESULTS: Our study shows the feasibility of locating AF sources with a success rate of greater than 95.25% within average 7.56 ± 2.28 placements independently of the initial position of the catheter and the source type. CONCLUSIONS: The algorithm could play a critical role in clinical electrophysiology laboratories for mapping patient-specific ablation of AF sources located outside the pulmonary veins and improving the procedure success.

18.
J Cardiovasc Electrophysiol ; 30(5): 758-768, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30725499

RESUMO

INTRODUCTION: Targeting repeating-pattern atrial fibrillation (AF) sources (reentry or focal drivers) can help in patient-specific ablation therapy for AF; however, the development of reliable and accurate tools for locating such sources remains a major challenge. We describe iterative catheter navigation (ICAN) algorithm to locate AF drivers using a conventional circular Lasso catheter. METHODS AND RESULTS: At each step, the algorithm analyzes 10 bipolar electrograms recoded at a given catheter location and the history of previous catheter movements to determine if the source is inside the catheter loop. If not, it calculates new coordinates and selects a new position for the catheter. The process continues until a source is located. The algorithm was evaluated in a computer model of atrial tissue with various degrees of fibrosis under a broad range of arrhythmia scenarios. The latter included slow and fast reentry, macroreentry, figure-of-eight reentry, and fibrillatory conduction. Depending on the initial distance of the catheter from the source and scenario, it took about 3 to 16 steps to localize an AF source. In 94% of cases, the identified location was within 4 mm from the source, independently of the initial position of the catheter. The algorithm worked equally well in the presence of patchy fibrosis, low-voltage areas, fragmented electrograms, and dominant-frequency gradients. CONCLUSIONS: AF repeating-pattern sources can be localized using circular catheters without the need to map the entire tissue. The proposed algorithm has the potential to become a useful tool for patient-specific ablation of AF sources located outside the pulmonary veins.

19.
Card Electrophysiol Clin ; 11(1): 55-65, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30717853

RESUMO

Investigative works of the past 20 years have compiled extensive data on the effectiveness and implications of cardiac resynchronization therapy (CRT) in patients with heart failure. Since then, CRT has become a well-accepted and widely adapted adjunctive therapy for patients with heart failure with ventricular dyssynchrony. This overview discusses the updated knowledge on the benefits afforded with CRT and reviews the major clinical trials that have established CRT at its current practice. Based on the data, the indications of CRT and the timing of appropriate implant of CRT devices with respect to heart failure status will be presented.


Assuntos
Terapia de Ressincronização Cardíaca , Insuficiência Cardíaca/terapia , Bloqueio de Ramo , Dispositivos de Terapia de Ressincronização Cardíaca , Ensaios Clínicos como Assunto , Humanos
20.
Ann Am Thorac Soc ; 16(3): 356-362, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30407869

RESUMO

RATIONALE: Low-tidal volume ventilation (LTVV; 6 ml/kg) benefits patients with acute respiratory distress syndrome and may aid those with other causes of respiratory failure. Current early ventilation practices are poorly defined. OBJECTIVES: We observed patients with acute respiratory failure to assess the feasibility of a pragmatic trial of LTVV and to guide experimental design. METHODS: We prospectively enrolled consecutive patients with acute respiratory failure admitted to intensive care units expected to participate in the proposed trial. We collected clinical data as well as information on initial and daily ventilator settings and inpatient mortality. We estimated the benefit of LTVV using predictive linear and nonlinear models. We simulated models to estimate power and feasibility of a cluster-randomized trial of LTVV versus usual care in acute respiratory failure. RESULTS: We included 2,484 newly mechanically ventilated patients (31% with acute respiratory distress syndrome) from 49 hospitals. Hospital mortality was 28%. Mean initial tidal volume was 7.1 ml/kg predicted body weight (95% confidence interval, 7.1-7.2), with 78% of patients receiving tidal volumes less than or equal to 8 ml/kg. Our models estimated a mortality benefit of 0-2% from LTVV compared with usual care. Simulation of a stepped-wedged cluster-randomized trial suggested that enrollment of 106,361 patients would be necessary to achieve greater than 90% power. CONCLUSIONS: Use of initial tidal volumes less than 8 ml/kg predicted body weight was common at hospitals participating in the National Heart, Lung, and Blood Institute Prevention and Early Treatment of Acute Lung Injury (PETAL) Network. After considering the size and budgetary requirement for a cluster-randomized trial of LTVV versus usual care in acute respiratory failure, the PETAL Network deemed the proposed trial infeasible. A rapid observational study and simulations to model anticipated power may help better design trials.

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