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Abstract Assisted/supported modes of mechanical ventilation offer significant advantages over controlled modes in terms of ventilator muscle function/recovery and patient comfort (and sedation needs). However, assisted/supported breaths must interact with patient demands during all three phases of breath delivery: trigger, target, and cycle. Synchronous interactions match ventilator support with patient demands; dyssynchronous interactions do not. Dyssynchrony imposes high pressure loads on ventilator muscles, promoting muscle overload/fatigue and increasing sedation needs. On current modes of ventilation there are a number of features that can monitor and enhance synchrony. These include adjustments of the trigger variable, the use of pressure versus fixed flow targeted breaths, and a number of manipulations of the cycle variable. Clinicians need to know how to use these modalities and monitor them properly, especially understanding airway pressure and flow graphics. Future strategies are emerging that have theoretical appeal but they await good clinical outcome studies before they become commonplace.

The American Thoracic Society committee on Proficiency Standards for Pulmonary Function Laboratories has recognized the need for a standardized reporting format for pulmonary function tests. Although prior documents have offered guidance on the reporting of test data, there is considerable variability in how these results are presented to end users, leading to potential confusion and miscommunication. A project task force, consisting of the committee as a whole, was approved to develop a new Technical Standard on reporting pulmonary function test results. Three working groups addressed the presentation format, the reference data supporting interpretation of results, and a system for grading quality of test efforts. Each group reviewed relevant literature and wrote drafts that were merged into the final document. This document presents a reporting format in test-specific units for spirometry, lung volumes, and diffusing capacity that can be assembled into a report appropriate for a laboratory's practice. Recommended reference sources are updated with data for spirometry and diffusing capacity published since prior documents. A grading system is presented to encourage uniformity in the important function of test quality assessment. The committee believes that wide adoption of these formats and their underlying principles by equipment manufacturers and pulmonary function laboratories can improve the interpretation, communication, and understanding of test results.

Abstract Due to growing interest in management of central airway obstruction, rigid bronchoscopy is undergoing a resurgence in popularity among pulmonologists. Performing rigid bronchoscopy requires use of deep sedation or general anesthesia to achieve adequate patient comfort, whereas maintaining oxygenation and ventilation via an uncuffed and often open rigid bronchoscope requires use of ventilation strategies that may be unfamiliar to most pulmonologists. Available approaches include apneic oxygenation, spontaneous assisted ventilation, controlled ventilation, manual jet, and high-frequency jet ventilation. Anesthetic technique is partially dictated by the selected ventilation strategy but most often relies on a total intravenous anesthetic approach using ultra–short-acting sedatives and hypnotics for a rapid offset of action in this patient population with underlying respiratory compromise. Gas anesthetic may be used with the rigid bronchoscope, minimizing leaks with fenestrated caps placed over the ports, although persistent circuit leaks can make this approach challenging. Jet ventilation, the most commonly used ventilatory approach, may be delivered manually using a Sanders valve or via an automated ventilator at supraphysiologic respiratory rates, allowing for an open rigid bronchoscope to facilitate ease of moving tools in and out of the airway. Despite a patient population that often suffers from significant respiratory compromise, major complications with rigid bronchoscopy are uncommon and are similar among modern ventilation approaches. Choice of ventilation technique should be determined by local expertise and equipment availability. Appropriate patient selection and recognition of limitations associated with a given ventilation strategy are critical to avoid procedural-related complications.

Patients requiring prolonged mechanical ventilation (PMV) are rapidly increasing in number, as improved ICU care has resulted in many patients surviving acute respiratory failure only to then require prolonged mechanical ventilatory assistance during convalescence. This patient population has clearly different needs and resource consumption patterns than patients in acute ICUs, and specialized venues, management strategies, and reimbursement schemes for them are rapidly emerging. To address these issues in a comprehensive way, a conference on the epidemiology, care, and overall management of patients requiring PMV was held. The goal was to not only review existing practices but to also develop recommendations on a variety of assessment, management, and reimbursement issues associated with patients requiring PMV. Formal presentations were made on a variety of topics, and writing groups were formed to address three specific areas: epidemiology and outcomes, management and care settings, and reimbursement. Each group was charged with summarizing current data and practice along with formulation of recommendations. A working draft of the products of these three groups was then created and circulated among all participants. The document was reworked with input from all concerned until a final product with consensus recommendations on 12 specific issues was achieved.

Impaired single breath carbon monoxide diffusing capacity (DLCO) is associated with emphysema. Small airways disease (SAD) may be a precursor lesion to emphysema, but the relationship between SAD and DLCO is undescribed. We hypothesized that in mild COPD, functional SAD (fSAD) defined by computed tomography (CT) and Parametric Response Mapping methodology would correlate with impaired DLCO. Using data from ever-smokers in the COPDGene cohort, we established that fSAD correlated significantly with lower DLCO among both non-obstructed and GOLD 1–2 subjects. The relationship between DLCO with CT-defined emphysema was present in all GOLD stages, but most prominent in severe disease. Trial registration NCT00608764 . Registry: COPDGene. Registered 06 February 2008, retrospectively registered.

The Global Lung Initiative (GLI) provides age-appropriate criteria for establishing spirometric impairment, including mild, moderate, and severe chronic obstructive pulmonary disease (COPD) and restrictive pattern, but its association with respiratory-related phenotypes has not been evaluated. To evaluate respiratory-related phenotypes in GLI-defined spirometric impairment. In COPDGene (N = 10,131 patients; age range, 45-81 yr; average smoking history, 44.3 pack-years), we evaluated spirometry, dyspnea (modified Medical Research Council grade, ≥2), poor respiratory health-related quality of life (St. George's Respiratory Questionnaire total score, ≥25), poor exercise performance (6-minute-walk distance, <391 m), bronchodilator reversibility (FEV1 change, >12% and ≥200 ml), and computed tomography-diagnosed emphysema and gas trapping (>5% and >15% of lung, respectively). GLI established normal spirometry in 5,100 patients (50.3%), mild COPD in 669 (6.6%), moderate COPD in 865 (8.5%), severe COPD in 2,522 (24.9%), and restrictive pattern in 975 (9.6%). Relative to normal spirometry, graded associations with respiratory-related phenotypes were found for mild, moderate, and severe COPD, with respective adjusted odds ratios (95% confidence intervals) as follows: dyspnea-1.31 (1.10-1.56), 2.20 (1.81-2.68), and 10.73 (8.04-14.33); poor respiratory health-related quality of life-1.49 (1.28-1.75), 2.69 (2.08-3.47), and 14.61 (10.09-21.17); poor exercise performance-1.11 (0.94-1.31), 1.58 (1.33-1.88), and 4.58 (3.42-6.12); bronchodilator reversibility-2.76 (2.24-3.40), 5.18 (4.29-6.27), and 6.21 (5.06-7.62); emphysema-4.86 (3.16-7.47), 6.41 (4.09-10.05), and 17.79 (10.79-29.32); and gas trapping-3.92 (3.12-4.93), 5.20 (3.82-7.07), and 16.28 (9.71-27.30). Restrictive pattern was also associated with multiple respiratory-related phenotypes at a level similar to moderate COPD, but it was otherwise not associated with emphysema (0.89 [0.60-1.32]) or gas trapping (1.15 [0.92-1.42]). GLI-defined spirometric impairment establishes clinically meaningful respiratory disease, as validated by graded associations with respiratory-related phenotypes.

Lawsonia intracellularis is an obligate intracellular bacterial pathogen that causes proliferative enteropathy (PE) in pigs. L. intracellularis infection causes extensive intestinal crypt cell proliferation and inhibits secretory and absorptive cell differentiation. However, the affected host upstream cellular pathways leading to PE are still unknown. β-catenin/Wnt signalling is essential in maintaining intestinal stem cell (ISC) proliferation and self-renewal capacity, while Notch signalling governs differentiation of secretory and absorptive lineage specification. Therefore, in this report we used immunofluorescence (IF) and quantitative reverse transcriptase PCR (RTqPCR) to examine β-catenin/Wnt and Notch-1 signalling levels in uninfected and L. intracellularis infected pig ileums at 3, 7, 14, 21 and 28 days post challenge (dpc). We found that while the significant increase in Ki67+ nuclei in crypts at the peak of L. intracellularis infection suggested enhanced cell proliferation, the expression of c-MYC and ASCL2, promoters of cell growth and ISC proliferation respectively, was down-regulated. Peak infection also coincided with enhanced cytosolic and membrane-associated β-catenin staining and induction of AXIN2 and SOX9 transcripts, both encoding negative regulators of β-catenin/Wnt signalling and suggesting a potential alteration to β-catenin/Wnt signalling levels, with differential regulation of the expression of its target genes. We found that induction of HES1 and OLFM4 and the down-regulation of ATOH1 transcript levels was consistent with the increased Notch-1 signalling in crypts at the peak of infection. Interestingly, the significant down-regulation of ATOH1 transcript levels coincided with the depletion of MUC2 expression at 14 dpc, consistent with the role of ATOH1 in promoting goblet cell maturation. The lack of significant change to LGR5 transcript levels at the peak of infection suggested that the crypt hyperplasia was not due to the expansion of ISC population. Overall, simultaneous induction of Notch-1 signalling and the attenuation of β-catenin/Wnt pathway appear to be associated with the inhibition of goblet cell maturation and enhanced crypt cell proliferation at the peak of L. intracellularis infection. Moreover, the apparent differential regulation of apoptosis between crypt and lumen cells together with the strong induction of Notch-1 signalling and the enhanced SOX9 expression along crypts 14 dpc suggest an expansion of actively dividing transit amplifying and/or absorptive progenitor cells and provide a potential basis for understanding the development and maintenance of PE.

Pulmonary rehabilitation (PR) after exacerbation of chronic obstructive pulmonary disease (COPD) is effective in reducing COPD hospitalizations and mortality while improving health-related quality of life, yet use of PR remains low. Estimates of the cost-effectiveness of PR in this setting could inform policies to improve uptake. To estimate the cost-effectiveness of participation in PR after hospitalization for COPD. This economic evaluation estimated the cost-effectiveness of participation in PR compared with no PR after COPD hospitalization in the US using a societal perspective analysis. A Markov microsimulation model was developed to estimate the cost-effectiveness in the US health care system with a lifetime horizon, 1-year cycle length, and a discounted rate of 3% per year for both costs and outcomes. Data sources included published literature from October 1, 2001, to April 1, 2021, with the primary source being an analysis of Medicare beneficiaries living with COPD between January 1, 2014, and December 31, 2015. The analysis was designed and conducted from October 1, 2019, to December 15, 2021. A base case microsimulation, univariate analyses, and a probabilistic sensitivity analysis were performed. Pulmonary rehabilitation compared with no PR after COPD hospitalization. Net cost in US dollars, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio. Among the hypothetical cohort with a mean age of 76.9 (age range, 60-92) years and 58.6% women, the base case microsimulation from a societal perspective demonstrated that PR resulted in net cost savings per patient of $5721 (95% prediction interval, $3307-$8388) and improved quality-adjusted life expectancy (QALE) (gain of 0.53 [95% prediction interval, 0.43-0.63] years). The findings of net cost savings and improved QALE with PR did not change in univariate analyses of patient age, the Global Initiative for Obstructive Lung Disease stage, or number of PR sessions. In a probabilistic sensitivity analysis, PR resulted in net cost savings and improved QALE in every one of 1000 samples and was the dominant strategy in 100% of simulations at any willingness-to-pay threshold. In a 1-way sensitivity analysis of total cost, assuming completion of 36 sessions, a single PR session would remain cost saving to $171 per session and had an incremental cost-effectiveness ratio of $884 per session for $50 000/QALY and $1597 per session for $100 000/QALY. In this economic evaluation, PR after COPD hospitalization appeared to result in net cost savings along with improvement in QALE. These findings suggest that stakeholders should identify policies to increase access and adherence to PR for patients with COPD.