With body growth from childhood, the lungs can enlarge by either increasing the volume of air in the periphery (as would occur with inspiration) or by increasing the number of peripheral acinar units. In the former case, the lung tissue density would decrease with inflation, whereas in the latter case, the lung density would be relatively constant as the lung grows. To address this fundamental structural issue, we measured the CT scan density in human subjects of widely varying size at two different lung volumes.

A large body of evidence demonstrates dose-response relationships of cumulative coal mine dust exposure with lung function impairment and with small-opacity profusion. However, medical literature generally holds that simple coal worker's pneumoconiosis (CWP) is not associated with lung function impairment. This study examines the relationship between small-opacity profusion and lung function in US underground coal miners with simple CWP.

Mortality risk prediction tools have been developed in idiopathic pulmonary fibrosis, however, it is unknown whether these models accurately estimate mortality in systemic sclerosis-associated interstitial lung disease (SSc-ILD).

Patients with systemic rheumatic diseases (SRDs) may require ICU management for SRD exacerbation or treatment-related infections or toxicities.

In COPD, a decreased inspiratory capacity to total lung capacity ratio (IC/TLC) is associated with dynamic hyperinflation and poor exercise capacity. The association with upper-extremity force measured by handgrip strength (HGS) and 6-min walk distance (6MWD) has not been previously described. We hypothesized that IC/TLC affects muscle strength in the upper and lower extremities, affecting HGS and 6MWD.

Sleep-disordered breathing (SDB) has a high prevalence in sarcoidosis. This high prevalence may be the result of increased upper airways resistance from sarcoidosis of the upper respiratory tract, corticosteroid-induced obesity, or parenchymal lung involvement from sarcoidosis. OSA is a form of SDB that is particularly common in patients with sarcoidosis. Sarcoidosis and SDB share many similar symptoms and clinical findings, including fatigue, gas exchange abnormalities, and pulmonary hypertension (PH). Sarcoidosis-associated fatigue is a common entity for which stimulants may be beneficial. Sarcoidosis-associated fatigue is a diagnosis of exclusion that requires an evaluation for the possibility of OSA. Hypercapnia is unusual in a patient with sarcoidosis without severe pulmonary dysfunction and, in this situation, should prompt evaluation for alternative causes of hypercapnia, such as SDB. PH is usually mild when associated with OSA, whereas the severity of sarcoidosis-associated PH is related to the severity of sarcoidosis. PH caused by OSA usually responds to CPAP, whereas sarcoidosis-associated PH commonly requires the use of vasodilators. Management of OSA in sarcoidosis is problematic because corticosteroid treatment of sarcoidosis may worsen OSA. Aggressive efforts should be made to place the patient on the lowest effective dose of corticosteroids, which involves early consideration of corticosteroid-sparing agents. Because of the significant morbidity associated with SDB, early recognition and treatment of SDB in patients with sarcoidosis may improve their overall quality of life.

Recent legislative successes allowing expanded access to recreational and medicinal cannabis have been associated with its increased use by the public, despite continued debates regarding its safety within the medical and scientific communities. Despite legislative changes, cannabis is most commonly used by smoking, although alternatives to inhalation have also emerged. Moreover, the composition of commercially available cannabis has dramatically changed in recent years. Therefore, developing sound scientific information regarding its impact on lung health is imperative, particularly because published data conducted prior to widespread legalization are conflicting and inconclusive. In this commentary, we delineate major observations of epidemiologic investigations examining cannabis use and the potential associated development of airways disease and lung cancer to highlight gaps in pulmonary knowledge. Additionally, we review major histopathologic alterations related to smoked cannabis and define specific areas in animal models and human clinical translational investigations that could benefit from additional development. Given that cannabis has an ongoing classification as a schedule I medication, federal funding to support investigations of modern cannabis use in terms of medicinal efficacy and safety profile on lung health have been elusive. It is clear, however, that the effects of inhaled cannabis on lung health remain uncertain and given increasing use patterns, are worthy of further investigation.

Pathogenic causes of acute hypoxemic respiratory failure (AHRF) can be difficult to identify at early clinical presentation. We evaluated the diagnostic utility of combined cardiac and thoracic critical care ultrasonography (CCUS).

Interstitial lung disease (ILD) is a heterogeneous group of rare diseases that primarily affect the pulmonary interstitium. Studies have implicated a role for telomere length (TL) maintenance in ILD, particularly in idiopathic interstitial pneumonia (IIP). Here, we measure TL in a wide spectrum of sporadic and familial cohorts of ILD and compare TL between patient cohorts and control subjects.

Lung expansion techniques (LETs) are widely used to prevent postoperative pulmonary complications (PPCs). However, the effects of each of these techniques on thoracoabdominal mechanics and PPC incidence after abdominal surgery remain unclear. The objective of this study was to compare the effects of LET on pulmonary volumes, respiratory muscle activation, and PPC incidence after major, elective upper abdominal surgery.

Despite advances in antimicrobial chemotherapy and access to sophisticated intensive care facilities, bacterial community-acquired pneumonia (CAP) continues to carry an unacceptably high mortality rate of 10% to 15% in hospitalized cases. CAP, considered by many to be the most underestimated disease worldwide, poses a particular threat to the elderly whose numbers are steadily increasing in developed countries. Indeed, elderly patients with severe CAP, as well as those with other risk factors, are at significant risk for development of inflammation-mediated acute cardiac events that may undermine the success of antimicrobial therapy. Adjunctive antiinflammatory strategies are, therefore, of considerable potential benefit in this setting. Currently, the most promising of these are the macrolides, corticosteroids, and, more recently, statins, all of which target immune/inflammatory cells. In addition, recent insights into the immunopathogenesis of acute coronary events in patients with CAP have revealed a probable pivotal role of platelet activation, potentially modifiable by agents that possess antiinflammatory or platelet-targeted activities or both. Statins, which not only possess antiinflammatory activity but also appear to target several pathways involved in platelet activation, seem particularly well suited as adjuncts to antibiotic therapy in bacterial CAP. Following a brief consideration of the immunopathogenesis of bacterial CAP, this review is focused on mechanisms of platelet activation by CAP pathogens, as well as the pharmacologic control thereof, with emphasis on statins.

Atrial fibrillation (AF) that newly occurs during critical illness presents challenges for both short- and long-term management. During critical illness, patients with new-onset AF are clinically evaluated for hemodynamic instability owing to the arrhythmia as well as for potentially reversible arrhythmia triggers. Hemodynamically significant AF that persists during critical illness may be treated with heart rate or rhythm control strategies. Recent evidence suggests that patients in whom AF develops during acute illness (eg, sepsis, postoperatively) have high long-term risks for AF recurrence and for AF-associated complications, such as stroke, heart failure, and death. Therefore, we suggest increased efforts to improve communication of AF events between inpatient and outpatient providers and to reassess patients who had experienced new-onset AF during critical illness after they transition to the post-ICU setting. We describe various strategies for the assessment and long-term management of patients with new-onset AF during critical illness.

A central tenet of caring for patients with ARDS is to treat the underlying cause, be it sepsis, pneumonia, or removal of an offending toxin. Identifying the risk factor for ARDS has even been proposed as essential to diagnosing ARDS. Not infrequently, however, the precipitant for acute hypoxemic respiratory failure is unclear, and this raises the question of whether a histologic lung diagnosis would benefit the patient. In this review, we consider the historic role of pathology in establishing a diagnosis of ARDS and the published experience of surgical and transbronchial lung biopsy in patients with ARDS. We reflect on which pathologic diagnoses influence treatment and suggest a patient-centric approach to weigh the risks and benefits of a lung biopsy for critically ill patients who may have ARDS.

Investigators believe most patients with asthma have reversible airflow obstruction with treatment, despite airway remodeling and hyperresponsiveness. There are smokers with chronic expiratory airflow obstruction despite treatment who have features of both asthma and COPD. Some investigators refer to this conundrum as the asthma-COPD overlap syndrome (ACOS). Furthermore, a subset of treated nonsmokers with moderate to severe asthma have persistent expiratory airflow limitation, despite partial reversibility. This residuum has been assumed to be due to large and especially small airway remodeling. Alternatively, we and others have described reversible loss of lung elastic recoil in acute and persistent loss in patients with moderate to severe chronic asthma who never smoked and its adverse effect on maximal expiratory airflow. The mechanism(s) responsible for loss of lung elastic recoil and persistent expiratory airflow limitation in nonsmokers with chronic asthma consistent with ACOS remain unknown in the absence of structure-function studies. Recently we reported a new pathophysiologic observation in 10 treated never smokers with asthma with persistent expiratory airflow obstruction, despite partial reversibility: All 10 patients with asthma had a significant decrease in lung elastic recoil, and unsuspected, microscopic mild centrilobular emphysema was noted in all three autopsies obtained although it was not easily identified on lung CT scan. These sentinel pathophysiologic observations need to be confirmed to further unravel the epiphenomenon of ACOS. The proinflammatory and proteolytic mechanism(s) leading to lung tissue breakdown need to be further investigated.

There has been a significant increase in the publication of clinical practice guidelines (CPGs) for respiratory diseases in China. However, little is known about the quality and potential impacts of these CPGs. Our objective was to critically evaluate the quality of Chinese CPGs for respiratory diseases that were published in peer-reviewed medical journals.

Lung-dominant connective tissue disease (LD-CTD) is a disease concept for interstitial pneumonia; however, it has not been robustly validated. This study was conducted to elucidate the clinical, radiologic, and histologic features of LD-CTD.

Central sleep apnea (CSA), in association with obstructive disordered breathing, occurs in patients using opioids long-term and those with congestive heart failure. In these patients, treatment with CPAP frequently fails. The current adaptive servoventilation (ASV) devices are promising for the treatment of complex sleep-disordered breathing. These devices use algorithms to automatically titrate expiratory and inspiratory pressures. We hypothesized that an ASV device operating automatically would significantly reduce the frequency of breathing events in patients with mixed sleep apnea during polysomnography and with 3 months of treatment.

Snoring is extremely common in the general population and may indicate OSA. However, snoring is not objectively measured during polysomnography, and no standard treatment is available for primary snoring or when snoring is associated with mild forms of OSA. This study determined the effects of oropharyngeal exercises on snoring in minimally symptomatic patients with a primary complaint of snoring and diagnosis of primary snoring or mild to moderate OSA.

COPD ranks within the top three causes of mortality in the global burden of disease, yet it remains largely underdiagnosed. We assessed the underdiagnosis of COPD and its determinants in national and international surveys of general populations.

The innate inflammatory pathways involved in the frequent exacerbator phenotypes of asthma and COPD are not well understood. This study aimed to investigate airway innate immune activation and systemic inflammation as predictors of exacerbations in asthma and COPD.