No abstract

Background Little information is available about the geo-economic variations in demographics, management, and outcomes of patients with acute respiratory distress syndrome (ARDS). We aimed to characterise the effect of these geo-economic variations in patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE). Methods LUNG SAFE was done during 4 consecutive weeks in winter, 2014, in a convenience sample of 459 intensivecare units in 50 countries across six continents. Inclusion criteria were admission to a participating intensive-care unit (including transfers) within the enrolment window and receipt of invasive or non-invasive ventilation. One of the trial's secondary aims was to characterise variations in the demographics, management, and outcome of patients with ARDS. We used the 2016 World Bank countries classification to define three major geo-economic groupings, namely European high-income countries (Europe-High), high-income countries in the rest of the world (rWORLD-High), and middle-income countries (Middle). We compared patient outcomes across these three groupings. LUNG SAFE is registered with ClinicalTrials.gov, number NCT02010073. Findings Of the 2813 patients enrolled in LUNG SAFE who fulfilled ARDS criteria on day 1 or 2, 1521 (54%) were recruited from Europe-High, 746 (27%) from rWORLD-High, and 546 (19%) from Middle countries. We noted significant geographical variations in demographics, risk factors for ARDS, and comorbid diseases. The proportion of patients with severe ARDS or with ratios of the partial pressure of arterial oxygen (PaO 2) to the fractional concentration of oxygen in inspired air (F I O 2) less than 150 was significantly lower in rWORLD-High countries than in the two other regions. Use of prone positioning and neuromuscular blockade was significantly more common in Europe-High countries than in the other two regions. Adjusted duration of invasive mechanical ventilation and length of stay in the intensive-care unit were significantly shorter in patients in rWORLD-High countries than in Europe-High or Middle countries. High gross national income per person was associated with increased survival in ARDS; hospital survival was significantly lower in Middle countries than in Europe-High or rWORLD-High countries. Interpretation Important geo-economic differences exist in the severity, clinician recognition, and management of ARDS, and in patients' outcomes. Income per person and outcomes in ARDS are independently associated.

No abstract

The rabbit model of tuberculosis is attractive because of its pathophysiologic resemblance to the disease in humans. Rabbits are naturally resistant to infection but may manifest cavitary lung lesions. We describe here a novel approach that utilizes presensitization and bronchoscopic inoculation to reliably produce cavities in the rabbit model. With a fixed inoculum of bacilli, we were able to reproducibly generate cavities by using Mycobacterium bovis Ravenel, M. bovis AF2122, M. bovis BCG, M. tuberculosis H37Rv, M. tuberculosis CDC1551, and the M. tuberculosis CDC1551 ⌬sigC mutant. M. bovis infections generated cavitary CFU counts of 10 6 to 10 9 bacilli, while non-M. bovis species and BCG yielded CFU counts that ranged from 10 4 to 10 8 bacilli. Extrapulmonary dissemination was almost exclusively noted among rabbits infected with M. bovis Ravenel and AF2122. Though all of the species yielded secondary lesions at intrapulmonary sites, M. bovis infections led to the most apparent gross pathology. Using the M. tuberculosis icl and dosR gene expression patterns as molecular sentinels, we demonstrated that both the cavity wall and cavity lumen are microenvironments associated with hypoxia, upregulation of the bacterial dormancy program, and the use of host lipids for bacterial catabolism. This unique cavitary model provides a reliable animal model to study cavity pathogenesis and extrapulmonary dissemination.Tuberculosis (TB) continues to be a global public health problem, with approximately one-third of the world's population latently infected (14). Nine million active infections are diagnosed annually, and approximately two million people died of the disease last year (33). Cavitary pulmonary lesions are key means of disease transmission (1, 21). The lesions present an ideal environment for tremendous bacillary growth, with up to 10 7 to 10 9 organisms being able to be routinely cultured from a single cavity (4). High titers of bacilli also lead to an increased likelihood of antimicrobial resistance due to spontaneous mutations (11).For these reasons, animal models of cavity formation and TB disease transmission have been sought. The murine model is limited because mice form cellular granuloma-like lesions which usually lack necrosis, caseation, and cavitation (16). Guinea pigs form necrotic granulomas with caseation but rarely produce cavitary lesions after aerosol Mycobacterium tuberculosis exposure (27). However, rabbits form caseating, necrotic granulomas which, under the correct conditions, may liquefy and cavitate.Early investigations by Wells and Lurie yielded cavity formation in rabbits presensitized with heat-killed M. bovis and challenged with aerosolized low-dose M. bovis (32). The importance of presensitization was further elucidated by Ratcliffe and Wells in their demonstration that more numerous cavities develop after reinfection with high-dose M. bovis following an initial primary low-dose aerosolized infection (23). Yamamura et al. reliably produced lung cavities in rabbits 30 to 60 days after in...