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OBJECTIVE: To assess the relationship between volume of nonoperative mechanically ventilated patients receiving care in a specific Veterans Health Administration hospital and their mortality. DESIGN: Retrospective cohort study. SETTING: One-hundred nineteen Veterans Health Administration medical centers. PATIENTS: We identified 5,131 hospitalizations involving mechanically ventilated patients in an intensive care unit during 2009, who did not receive surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We extracted demographic and clinical data from the VA Inpatient Evaluation Center. For each hospital, we defined volume as the total number of nonsurgical admissions receiving mechanical ventilation in an intensive care unit during 2009. We examined the hospital contribution to 30-day mortality using multilevel logistic regression models with a random intercept for each hospital. We quantified the extent of interhospital variation in 30-day mortality using the intraclass correlation coefficient and median odds ratio. We used generalized estimating equations to examine the relationship between volume and 30-day mortality and risk-adjusted all models using a patient-level prognostic score derived from clinical data representing the risk of death conditional on treatment at a high-volume hospital. Mean age for the sample was 65 (SD 11) yrs, 97% were men, and 60% were white. The median VA hospital cared for 40 (interquartile range 19-62) mechanically ventilated patients in 2009. Crude 30-day mortality for these patients was 36.9%. After reliability and risk adjustment to the median patient, adjusted hospital-level mortality varied from 33.5% to 40.6%. The intraclass correlation coefficient for the hospital-level variation was 0.6% (95% confidence interval 0.1, 3.4%), with a median odds ratio of 1.15 (95% confidence interval 1.06, 1.38). The relationship between hospital volume of mechanically ventilated and 30-day mortality was not statistically significant: each 50-patient increase in volume was associated with a nonsignificant 2% decrease in the odds of death within 30 days (odds ratio 0.98, 95% confidence interval 0.87-1.10). CONCLUSIONS: Veterans Health Administration hospitals caring for lower volumes of mechanically ventilated patients do not have worse mortality. Mechanisms underlying this finding are unclear, but, if elucidated, may offer other integrated health systems ways to overcome the disadvantages of small-volume centers in achieving good outcomes. [ABSTRACT FROM AUTHOR]

Rationale: Lack of health insurance maybe an independent risk factor for mortality and differential treatment in critical illness.Objectives: To determine whether uninsured critically ill patients had differences in 30-day mortality and critical care service use compared with those with private insurance and to determine if outcome variability could be attributed to patient-level or hospital-level effects.Methods: Retrospective cohort study using Pennsylvania hospital discharge data with detailed clinical risk adjustment, from fiscal years 2005 and 2006, consisting of 167 general acute care hospitals, with 138,720 critically ill adult patients 64 years of age or younger.Measurements and Main Results: Measurements were 30-day mortality and receipt of five critical care procedures. Uninsured patients had an absolute 30-day mortality of 5.7%, compared with 4.6% for those with private insurance and 6.4% for those with Medicaid. Increased 30-day mortality among uninsured patients persisted after adjustment for patient characteristics (odds ratio [OR], 1.25 for uninsured vs. insured; 95% confidence interval [CI], 1.04–1.50) and hospital-level effects (OR, 1.26; 95% CI, 1.05–1.51). Compared with insured patients, uninsured patients had decreased risk-adjusted odds of receiving a central venous catheter (OR, 0.84; 95% CI,0.72–0.97), acute hemodialysis (OR, 0.59; 95% CI, 0.39–0.91), and tracheostomy (OR, 0.43; 95% CI, 0.29–0.64).Conclusions: Lack of health insurance is associated with increased 30-day mortality and decreased use of common procedures for the critically ill in Pennsylvania. Differences were not attributable to hospital-level effects, suggesting that the uninsured have a higher mortality and receive fewer procedures when compared with privately insured patients treated at the same hospitals. [ABSTRACT FROM AUTHOR]

BACKGROUND: Endotracheal suctioning is required but can have adverse effects, and could affect cardiorespiratory variables that are used to predict whether the patient is ready for extubation. METHODS: In a prospective cohort study in a university hospital's medical intensive care unit, we measured the impact of closed-system suctioning on cardiopulmonary variables in spontaneously breathing patients weaning from mechanical ventilation. All spontaneously breathing, mechanically ventilated patients were screened for enrollment at the initiation of weaning from mechanical ventilation. Before, during, and after standardized closed-system endotracheal suctioning we measured minute volume, heart rate, arterial oxygen saturation, mean arterial pressure, respiratory frequency, oxygen saturation, and tidal volume. RESULTS: Twenty-nine patients were enrolled after a median of 5 (interquartile range [IQR] 3-9) ventilator days. Twenty-five patients (86%) were spontaneously breathing on pressure-support ventilation when suctioned. The median post-suctioning recovery time was > 5 min for minute volume, tidal volume, respiratory rate, and ratio of respiratory rate to tidal volume. The post-suctioning median values of the maximum deviations in the ventilatory variables were clinically important: minute volume -2.4 (IQR 1.6-3.7) L/min, respiratory rate 8 (IQR 2-14) breaths/min, tidal volume -175 (108-220) mL. Heart rate, mean arterial pressure, and oxygen saturation increased after suctioning (P < .05), but the increases were not clinically important. CONCLUSIONS: Post-suctioning changes in the measured variables persisted longer in these spontaneously breathing patients weaning from mechanical ventilation than in patients who are sedated and paralyzed. The effects of suctioning on cardiopulmonary function should be considered in practice and during the design of future studies on weaning and extubation prediction variables. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Studies describing predictors of mortality in patients with acute lung injury were primarily derived from selected academic centers. We sought to determine the predictors of mortality in a population-based cohort of patients with acute lung injury and to characterize the performance of current severity of illness scores in this population. DESIGN: Secondary analysis of a prospective, multicenter, population-based cohort. SETTING: Twenty-one hospitals in Washington State. PATIENTS: The cohort included 1,113 patients with acute lung injury identified during the year 1999-2000. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We evaluated physiology, comorbidities, risk factors for acute lung injury, and other variables for their association with death at hospital discharge. Bivariate predictors of death were entered into a multiple logistic regression model. We compared Acute Physiology and Chronic Health Evaluation (APACHE) II, APACHE III, and Simplified Acute Physiology Score II to the multivariable model using area under the receiver operating characteristic curve. The model was validated in an independent cohort of 886 patients with acute lung injury. Modified acute physiology score, age, comorbidities, arterial pH, minute ventilation, PaCO2, PaO2/FiO2 ratio, intensive care unit admission source, and intensive care unit days before onset of acute lung injury were independently predictive of in-hospital death (p < .05). The area under the receiver operating characteristic curve for the multivariable model was superior to that of APACHE III (.81 vs. .77, p < .001) but was no different after external validation (.71 vs. .70, p = .64). CONCLUSIONS: The predictors of mortality in patients with acute lung injury are similar to those predictive of mortality in the general intensive care unit population, indicating disease heterogeneity within this cohort. Accordingly, APACHE III predicts mortality in acute lung injury as well as a model using variables selected specifically for patients with acute lung injury. [ABSTRACT FROM AUTHOR]

Introduction: In this study, we sought to determine the association between red blood cell (RBC) transfusion and outcomes in patients with acute lung injury (ALI), sepsis and shock.Methods: We performed a secondary analysis of new-onset ALI patients enrolled in the Acute Respiratory Distress Syndrome Network Fluid and Catheter Treatment Trial (2000 to 2005) who had a documented ALI risk factor of sepsis or pneumonia and met shock criteria (mean arterial pressure (MAP) < 60 mmHg or vasopressor use) within 24 hours of randomization. Using multivariable logistic regression, we examined the association between RBC transfusion and 28-day mortality after adjustment for age, sex, race, randomization arm and Acute Physiology and Chronic Health Evaluation III score. Secondary end points included 90-day mortality and ventilator-free days (VFDs). Finally, we examined these end points among the subset of subjects meeting prespecified transfusion criteria defined by five simultaneous indicators: hemoglobin < 10.2 g/dL, central or mixed venous oxygen saturation < 70%, central venous pressure ≥ 8 mmHg, MAP ≥ 65 mmHg, and vasopressor use.Results: We identified 285 subjects with ALI, sepsis, shock and transfusion data. Of these, 85 also met the above prespecified transfusion criteria. Fifty-three (19%) of the two hundred eighty-five subjects with shock and twenty (24%) of the subset meeting the transfusion criteria received RBC transfusion within twenty-four hours of randomization. We found no independent association between RBC transfusion and 28-day mortality (odds ratio = 1.49, 95% CI (95% confidence interval) = 0.77 to 2.90; P = 0.23) or VFDs (mean difference = -0.35, 95% CI = -4.03 to 3.32; P = 0.85). Likewise, 90-day mortality and VFDs did not differ by transfusion status. Among the subset of patients meeting the transfusion criteria, we found no independent association between transfusion and mortality or VFDs.Conclusions: In patients with new-onset ALI, sepsis and shock, we found no independent association between RBC transfusion and mortality or VFDs. The physiological criteria did not identify patients more likely to be transfused or to benefit from transfusion. [ABSTRACT FROM AUTHOR]

Background: Double-blind peer review (DBPR, reviewers blinded to author identities and vice-versa) aims to reduce biases. DBPR's effectiveness has not been studied in pulmonary, critical care, and sleep journals., Research Question: What was the causal effect on bias of DBPR at CHEST?, Study Design and Methods: From January 2020 - June 2022, CHEST and Annals of the American Thoracic Society (AATS) used single-blind peer review (reviewers concealed from authors only); in July 2022, CHEST switched to DBPR. We estimated the causal effect of DBPR on manuscript acceptance at CHEST using AATS as a control. Our co-primary exposures were first and last author gender; secondarily, we considered author residence in English fluent countries. To estimate DBPR's differential impact by exposure, we constructed multivariable regression models with triple interaction terms (e.g., author gender X CHEST vs AATS X pre- vs post-DBPR), all component factors (e.g., author gender), paired interactions (e.g., author gender X CHEST vs AATS), and covariables (year, topic)., Results: We included 4,651 manuscripts (CHEST: 3,494; AATS: 1,157) sent for peer-review; 4,645 (99.9%) had identifiable author gender. From 2020-2024, CHEST submissions (compared to AATS) were less frequently authored by women (first: 38.7% vs 45.5%, SMD = 0.14; last: 23.9% vs 31.2% SMD = 0.16) or people from English fluent countries (first: 56.0% vs 77.7%, SMD = 0.47; last: 57.9% vs 79.0%, SMD = 0.47), and acceptance rates were lower (30.7% vs 48.4%, SMD = 0.37). After adjustment, no difference was appreciated in DBPR's impact on acceptance for women vs men authors (first: -7.4 [95% CI: -20.9 - 6.0] percentage points, p=0.28; last: -10.1 [-25.1 - 5.0] percentage points, p=0.19). DBPR negatively impacted first (but not last) authors from English fluent countries (vs non-fluent: -16.8 [-32.1 - -1.6] percentage points, p=0.030)., Interpretation: DBPR did not differentially impact authors by gender but did by presumed English fluency., (Copyright © 2025. Published by Elsevier Inc.)

Objectives: To compare outcomes for 2 weeks vs. 1 week of maximal patient-intensivist continuity in the ICU., Design: Retrospective cohort study., Setting: Two U.S. urban, teaching, medical ICUs where intensivists were scheduled for 2-week service blocks: site A was in the Midwest and site B was in the Northeast., Patients: Patients 18 years old or older admitted to a study ICU between March 1, 2017, and February 28, 2020., Interventions: None., Measurements and Main Results: We applied target trial emulation to compare admission during an intensivist's first week (as a proxy for 2 wk of maximal continuity) vs. admission during their second week (as a proxy for 1 wk of maximal continuity). Outcomes included hospital mortality, ICU length of stay, and, for mechanically ventilated patients, duration of ventilation. Exploratory outcomes included imaging, echocardiogram, and consultation orders. We used inverse probability weighting to adjust for baseline differences and random-effects meta-analysis to calculate overall effect estimates. Among 2571 patients, 1254 were admitted during an intensivist's first week and 1317 were admitted during a second week. At sites A and B, hospital mortality rates were 25.8% and 24.2%, median ICU length of stay were 4 and 2 days, and median mechanical ventilation durations were 3 and 3 days, respectively. There were no differences in adjusted mortality (odds ratio [OR], 1.01 [95% CI, 0.96-1.06]) or ICU length of stay (-0.25 d [-0.82 d to +0.32 d]) for 2 weeks vs. 1 week of maximal continuity. Among mechanically ventilated patients, there were no differences in adjusted mortality (OR, 1.00 [0.87-1.16]), ICU length of stay (+0.06 d [-0.78 d to +0.91 d]), or duration of mechanical ventilation (+0.37 d [-0.46 d to +1.21 d]) for 2 weeks vs. 1 week of maximal continuity., Conclusions: Two weeks of maximal patient-intensivist continuity was not associated with differences in clinical outcomes compared with 1 week in two medical ICUs., Competing Interests: Drs. Admon’s, Gershengorn’s, and Prescott’s institutions received funding from the National Heart, Lung, and Blood Institute. Drs. Admon, Law, and Valley received support for article research from the National Institutes of Health (NIH). Dr. Admon was funded by K08HL155407. Dr. Law’s institution received funding from the NIH. Dr. Gershengorn’s institution received funding from the Canadian Institutes for Health Research; she received funding from CHEST Critical Care, Annals of the American Thoracic Society, International Symposium on Intensive Care and Emergency Medicine, and Southeastern Critical Care Summit; and she received support from the University of Miami Hospital and Clinics Data Analytics Research Team. Dr. Prescott’s institution received funding from the Agency for Healthcare Research and Quality, Veterans Affairs Health Services Research and Development, the Centers for Disease Control and Prevention, and Blue Cross Blue Shield of Michigan; she disclosed government work. The remaining authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2024 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.)

Rationale: Intermediate care (also termed "step-down" or "moderate care") has been proposed as a lower cost alternative to care for patients who may not clearly benefit from intensive care unit admission. Intermediate care units may be appealing to hospitals in financial crisis, including those in rural areas. Outcomes of patients receiving intermediate care are not widely described. Objectives: To examine relationships among rurality, location of care, and mortality for mechanically ventilated patients. Methods: Medicare beneficiaries aged 65 years and older who received invasive mechanical ventilation between 2010 and 2019 were included. Multivariable logistic regression was used to estimate the association between admission to a rural or an urban hospital and 30-day mortality, with separate analyses for patients in general, intermediate, and intensive care. Models were adjusted for age, sex, area deprivation index, primary diagnosis, severity of illness, year, comorbidities, and hospital volume. Results: There were 2,752,492 hospitalizations for patients receiving mechanical ventilation from 2010 to 2019, and 193,745 patients (7.0%) were in rural hospitals. The proportion of patients in rural intermediate care increased from 4.1% in 2010 to 6.3% in 2019. Patient admissions to urban hospitals remained relatively stable. Patients in rural and urban intensive care units had similar adjusted 30-day mortality, at 46.7% (adjusted absolute risk difference -0.1% [95% confidence interval, -0.7% to 0.6%]; P  = 0.88). However, adjusted 30-day mortality for patients in rural intermediate care was significantly higher (36.9%) than for patients in urban intermediate care (31.3%) (adjusted absolute risk difference 5.6% [95% confidence interval, 3.7% to 7.6%]; P  < 0.001). Conclusions: Hospitalization in rural intermediate care was associated with increased mortality. There is a need to better understand how intermediate care is used across hospitals and to carefully evaluate the types of patients admitted to intermediate care units.

Purpose: Some hospitals in the United States (US) use intensive care 20 times more than others. Since intensive care is lifesaving for some but potentially harmful for others, there is a need to understand factors that influence how intensive care unit (ICU) admission decisions are made., Methods: A qualitative analysis of eight US hospitals was conducted with semi-structured, one-on-one interviews supplemented by site visits and clinical observations., Results: A total of 87 participants (24 nurses, 52 physicians, and 11 other staff) were interviewed, and 40 h were spent observing ICU operations across the eight hospitals. Four hospital-level factors were identified that influenced ICU admission decision-making. First, availability of intermediate care led to reallocation of patients who might otherwise be sent to an ICU. Second, participants stressed the importance of ICU nurse availability as a key modifier of ICU capacity. Patients cared for by experienced general care physicians and nurses were less likely to receive ICU care. Third, smaller or rural hospitals opted for longer emergency department patient-stays over ICU admission to expedite interhospital transfer of critically ill patients. Fourth, lack of clarity in ICU admission policies led clinicians to feel pressured to use ICU care for patients who might otherwise not have received it., Conclusion: Health care systems should evaluate their use of ICU care and establish institutional patterns that ensure ICU admission decisions are patient-centered but also account for resources and constraints particular to each hospital., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Rationale: The coronavirus disease (COVID-19) pandemic has negatively affected women more than men and may influence the publication of non-COVID-19 research. Objectives: To evaluate whether the COVID-19 pandemic is associated with changes in manuscript acceptance rates among pulmonary/critical care journals and sex-based disparities in these rates. Methods: We analyzed first, senior, and corresponding author sex (female vs. male, identified by matching first names in a validated Genderize database) of manuscripts submitted to four pulmonary/critical care journals between January 1, 2018 and December 31, 2020. We constructed interrupted time series regression models to evaluate whether the proportion of female first and senior authors of non-COVID-19 original research manuscripts changed with the pandemic. Next, we performed multivariable logistic regressions to evaluate the association of author sex with acceptance of original research manuscripts. Results: Among 8,332 original research submissions, women represented 39.9% and 28.3% of first and senior authors, respectively. We found no change in the proportion of female first or senior authors of non-COVID-19 or COVID-19 submitted research manuscripts during the COVID-19 era. Non-COVID-19 manuscripts submitted during the COVID-19 era had reduced odds of acceptance, regardless of author sex (first author adjusted OR [aOR], 0.46 [95% confidence interval (CI), 0.36-0.59]; senior author aOR, 0.46 [95% CI, 0.37-0.57]). Female senior authorship was associated with decreased acceptance of non-COVID-19 research manuscripts (crude rates, 14.4% [male] vs. 13.2% [female]; aOR, 0.84 [95% CI, 0.71-0.99]). Conclusions: Although female author submissions were not disproportionately influenced by COVID-19, we found evidence suggesting sex disparities in manuscript acceptance rates. Journals may need to consider strategies to reduce this disparity, and academic institutions may need to factor our findings, including lower acceptance rates for non-COVID-19 manuscripts, into promotion decisions.

Background: Early-career clinician-scientists often leave academic medicine, but strong mentorship can help facilitate retention. Beyond the traditional dyadic mentor-mentee relationship, formal peer mentoring provides a rich means to augment career development and foster independence., Objective: To describe a model for early-career peer mentorship and the retention of participating early-career clinician-scientists in academic medicine., Methods: In 2015, a multidisciplinary and interprofessional group of early-career clinician-scientists focused on critical care developed a peer mentoring group at the University of Michigan called the MICReW (Multidisciplinary Intensive Care Research Workgroup). We describe the establishment, sustainability, guiding principles, challenges, and successes of MICReW., Results: MICReW was established to be a formal, peer-only mentoring group without the direct participation of senior mentors. The purpose of MICReW was to support and promote the research and career development of early-career clinician-scientists by creating an environment that fostered diverse opinions, constructive feedback, and camaraderie. As a group, we wrote a mission statement and defined our guiding principles. Our sustainability, growth, and adaptability (seamlessly transitioning to all virtual meetings) were possible by the continued investment of our peer members. To date, MICReW has had 30 members, of whom 15 are current members and approximately half are women. Nearly all members ( n  = 29/30) remain in academic positions, and half ( n  = 15) have been awarded career development awards. Most members also report significant benefits from being a member of MICReW., Conclusion: The MICReW peer mentorship model is a sustainable and adaptable peer mentoring model whose members continue to be engaged in academic medicine., (Copyright © 2022 by the American Thoracic Society.)

Prediction models aim to use available data to predict a health state or outcome that has not yet been observed. Prediction is primarily relevant to clinical practice, but is also used in research, and administration. While prediction modeling involves estimating the relationship between patient factors and outcomes, it is distinct from casual inference. Prediction modeling thus requires unique considerations for development, validation, and updating. This document represents an effort from editors at 31 respiratory, sleep, and critical care medicine journals to consolidate contemporary best practices and recommendations related to prediction study design, conduct, and reporting. Herein, we address issues commonly encountered in submissions to our various journals. Key topics include considerations for selecting predictor variables, operationalizing variables, dealing with missing data, the importance of appropriate validation, model performance measures and their interpretation, and good reporting practices. Supplemental discussion covers emerging topics such as model fairness, competing risks, pitfalls of "modifiable risk factors", measurement error, and risk for bias. This guidance is not meant to be overly prescriptive; we acknowledge that every study is different, and no set of rules will fit all cases. Additional best practices can be found in the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) guidelines, to which we refer readers for further details.

Background: The aim of this project was to investigate the prevalence of nutrition consultation (NC) in U.S. intensive care units (ICUs) and to examine its association with patient outcomes., Methods: Data from the Healthcare Cost and Utilization Project's state inpatient databases was utilized from 2010 - 2014. A multilevel logistic regression model was used to evaluate the relationship between NC and clinical outcomes., Results: Institutional ICU NC rates varied significantly (mean: 14%, range: 0.1%-73%). Significant variation among underlying disease processes was identified, with burn patients having the highest consult rate (P < 0.001, mean: 6%, range: 2%-25%). ICU patients who received NC had significantly lower in-hospital mortality (odds ratio [OR] 0.59, 95% confidence interval [CI] 0.48-0.74, P < 0.001), as did the subset with malnutrition (OR 0.72, 95% CI 0.53-0.99, P = 0.047) and the subset with concomitant physical therapy consultation (OR 0.53, 95% CI 0.38-0.74, P < 0.001). NC was associated with significantly lower rates of intubation, pulmonary failure, pneumonia, and gastrointestinal bleeding (P < 0.05). Furthermore, patients who received NC were more likely to receive enteral or parenteral nutrition (ENPN) (OR 1.8, 95% CI 1.4-2.3, P < 0.001). Patients who received follow-up NC were even more likely to receive ENPN (OR 3.0, 95% CI 2.1-4.2, P < 0.001)., Conclusions: Rates of NC were low in critically ill patients. This study suggests that increased utilization of NC in critically ill patients may be associated with improved clinical outcomes., (© 2019 American Society for Parenteral and Enteral Nutrition.)

Objective: To evaluate whether changes in diagnosis assignment explain reductions in 30-day readmission for patients with pneumonia following the Hospital Readmission Reduction Program (HRRP)., Data Sources: 100 percent MedPAR, 2008-2015., Study Design: Retrospective cohort study of Medicare discharges in HRRP-eligible hospitals. Outcomes were 30-day readmission rates for pneumonia under a "narrow" definition (used for the HRRP until October 2015; n = 2 288 644) and a "broad" definition that included certain diagnoses of sepsis and aspiration pneumonia (used since October 2015; n = 3 618 215). We estimated changes in 30-day readmissions in the pre-HRRP period (January 2008-March 2010), the HRRP implementation period (April 2010-September 2012), and the HRRP penalty period (October 2012-June 2015)., Principal Findings: Under the narrow definition, adjusted annual readmission rates changed by +0.07 percentage points (pp) during the pre-HRRP period (95% CI: -0.03 pp, +0.18 pp), -1.07 pp during HRRP implementation (95% CI: -1.15 pp, -0.99 pp), and -0.09 pp during the penalty period (95% CI: -0.18 pp, -0.00 pp). Under the broad definition, 30-day readmissions changed by +0.21 pp during the pre-HRRP period (95% CI: +0.12 pp, +0.30 pp), -1.28 pp during HRRP implementation (95% CI: -1.35 pp, -1.21 pp), and -0.09 pp during the penalty period (95% CI: -0.16 pp, -0.02 pp)., Conclusions: Changes in the coding of inpatient pneumonia admissions do not explain readmission reduction following the HRRP., (© Health Research and Educational Trust.)

Rationale: The Affordable Care Act's Medicaid expansion has led to increased access to chronic disease care among newly insured adults. Despite this, its effects on clinical outcomes, particularly for patients with asthma, chronic obstructive pulmonary disease, and heart failure, are uncertain. Objectives: To assess whether Medicaid expansion was associated with changes in mechanical ventilation rates among hospitalized patients with heart failure, asthma, and chronic obstructive pulmonary disease. Methods: Difference-in-differences analysis comparing discharge data from four states that expanded Medicaid in 2014 (Arizona, Iowa, New Jersey, and Washington) and three comparison states that did not (North Carolina, Nebraska, and Wisconsin) was performed. Models were adjusted for patient and hospital factors. Results: Mechanical ventilation rates at baseline were 7.2% in nonexpansion states and 8.8% in expansion states. Medicaid expansion was associated with a decline in mechanical ventilation rates at -0.2% per quarter (95% confidence interval [CI], -0.3% to 0.0%; P  = 0.010). We did not observe a change in the rate of ICU admission (-0.4% per quarter; 95% CI, -0.8% to 0.1%; P  = 0.10) or in-hospital mortality (0.1% per quarter; 95% CI, 0.0% to 0.1%; P  = 0.30). In a negative control among adults aged 65 years or older, changes in mechanical ventilation rates were similar, though the CIs crossed zero (-0.1%; 95% CI, -0.2% to 0.0%; P  = 0.08). Conclusions: Medicaid expansion may have been associated with a decline in mechanical ventilation rates among uninsured and Medicaid-covered patients admitted with heart failure, chronic obstructive pulmonary disease, and asthma.