Current Respiratory Medicine Reviews - Volume 10, Issue 1, 2014

The invention of the bronchoscope is a result of in-depth research and scientific analysis by countless physicians and researchers, who toiled through difficulties to discover scientific instruments and techniques to ensure a better quality of life to their patient. Gustav Killian was the inventor of the bronchoscope, which was strongly propagated by several stalwarts in medicine resulting in the invention of advanced and innovative techniques and superior bronchoscopes starting with the rigid bronchoscope, flexible bronchoscope to endobronchial ultrasounds, microchip technology and so forth that are being discovered even today. We have attempted to present a brief glimpse of the history of bronchoscopy and the bronchoscopes.

Chronic obstructive lung disease is the fourth leading cause of death in the United States. Over the past two decades, attempts have been undertaken to improve the pulmonary status in patients with emphysema by performing lung volume reduction surgeries. Over these past decades, several bronchoscopic techniques have been proposed for lung volume reduction surgery, which include endobronchial valves, silicone balloons, Watanabe spigots, artificial accessory airways and endobronchial coils, to name a few. In addition, the endobronchial valve has been used to treat persistent air leaks. In the current article we will briefly discuss bronchoscopic techniques and devices for the treatment of the condition mentioned above.

Peripheral pulmonary nodules can present diagnostic challenges, especially in high risk patients. Surgical biopsy is the gold standard for establishing a diagnosis and can often serve as definitive treatment; however, there are associated risks, morbidities, and costs, which may be too high, especially if the result is a benign lesion. Bronchoscopy (with or without fluoroscopy) or imaging guided transthoracic needle aspiration can often determine the diagnosis in appropriate patients; navigational aids can often improve the yield of bronchoscopic biopsy. Navigational bronchoscopy guides the user to the lesion(s) of interest using computer software integrated with computed tomography images and an electromagnetic field generated around the patient. While this is a relatively new technology, several studies have demonstrated the efficacy and safety of the procedure. Navigational bronchoscopy is best used, along with transthoracic needle aspiration, endobronchial ultrasound (including radial probe), and surgical interventions, as part of a step-wise diagnostic approach to the evaluation of a peripheral pulmonary nodule.

Limited potential treatment options are available for the management of severe symptomatic asthma. Bronchial Thermoplasty is considered as a new treatment modality for adult patients with severe refractory asthma despite being on conventional pharmacotherapy. We will discuss the evidence for and against Bronchial Thermoplasty in the management of severe refractory asthma.

Percutaneous dilatational tracheostomy (PDT) is one of the most common procedures performed universally in patients admitted to medical and surgical intensive care units. Initially popularized in the 1980s, it can be performed by various techniques including Ciaglia’s blue Rhino, Griggs guide wire dilating forceps, Blue Dolphin, or the Perc Twist method. Bronchoscopy and ultrasound guidance have made these procedures much quicker and safer. Its main advantages over its centuries old counterpart, surgical tracheostomy (ST), include shorter procedure times, less perioperative bleeding, and a decreased risk of peristomal infection. PDT also appears to be more cost effective by preventing delays due to operating room scheduling issues and complications in transporting critically ill patients to the operating room for ST. Some patients, including those who are morbidly obese, those with prior tracheostomies, or patients with severe head and neck surgeries still remain good candidates for ST in general. Moreover, in experienced hands, PDT can also be performed. There are many physiological advantages of tracheostomy over the endotracheal tube such as reduction of airway resistance and anatomic dead space. Also, studies have shown decreased incidences of pneumonia, shorter inpatient stay length and reduced mortality with early tracheostomy. Nevertheless, the dilemma of appropriate timing to perform tracheostomy in the course of mechanical ventilation remains unanswered.

Historical evolution of airway stents began with the adaptation of endoprosthesis used in vascular and gastrointestinal procedures. In 1990, Jean-Francois Dumon published the first report of a dedicated silicone airway stent with a unique delivery system that continues to be used nowadays. Since then, additional developments in airway stenting have occurred such as the development of new alloys for self exapandable metallic stents with and without coverings. Stents are currently used for a wide variety of indications such as treatment of benign or malignant tracheobronchial stenosis with good symptom relief, quality of life and performance status scores in patients undergoing treatment for malignant airway involvement. Airway stents are also indicated in selected cases of benign airway obstruction and closure of trachea-esophageal or other types of fistulous tracts involving the central airways. Self-expandable metallic stents offer distinct advantages such as ease of placement, avoidance of use of general anesthetics and specific disadvantages such as granulation tissue formation and difficulty in manipulation and removal after placement. Current challenges in airway stenting include short and long term complications such as migration, granulation tissue, airway secretion management and stent infections. New technology is currently under development including drug-eluting airway stents, biodegradable stents and three-dimensional printing to achieve better conformation to the size and anatomy of the airway.

Refractory hypoxia in adult respiratory distress syndrome remains a highly lethal process. Low tidal volume ventilation maneuvers have improved outcomes. In severe Acute Respiratory Distress Syndrome (ARDS), the mortality remains high. Veno-Venous Extracorporeal Membranous Oxygenation (VV ECMO) has been employed to treat this very sick group of patients. The proper selection of patients for VV ECMO as well as proper critical care management while on ECMO remains the key to improved outcomes. This review article details the current state of the art therapy for VV ECMO for refractory hypoxia, and describes controversies and future directions.

The main treatment of asthma is inhaled corticosteroids. However adherence to these medications in asthma is often poor, with low adherence associated with excessive health care costs and an increased risk of emergency room visits and mortality. Although various methods are used to indirectly assess adherence, all have significant limitations whether used in clinical or research practice. The recent development of electronic monitoring devices (EMDs) for use with inhalers presents an exciting opportunity to easily and accurately measure inhaler adherence. This article summarises the current devices available; for each device features and limitations are considered, followed by a review of both the current clinical literature and data on reliability and accuracy. An overall summary is also provided to aid comparison of capabilities between devices and future issues pertaining to the use of EMDs are discussed, including barriers to adoption, stakeholder involvement, novel methods of communicating adherence data, recording of data and cloud storage. Finally key areas that still require investigation are highlighted.

Chronic bronchitis, pulmonary fibrosis, emphysema and allergic asthma are significant human health issues due to exposure to environmental pollutants, chemical irritants, cigarette smoke (CS) and allergens. Activation of the NLRP3 inflammasome with the release of active IL-1β is central to develop inflammatory lung pathology. We demonstrated that CS, microparticle (MP), bleomycin or allergens provoke the release of danger signals such as ATP and/or uric acid that activate the NLRP3 inflammasome. Activated NLPR3 recruits the adaptor protein ASC and activates caspase-1 with the release of mature IL-1β. IL-1β is a critical mediator of inflammation inducing IL-6, IL-23 as well as chemokines, which mobilize neutrophils and enhance the recruitment of Th17 cells in the lung with the production of IL- 17. Here, we review our experimental investigations that uncovered danger signals activating the NLRP3 inflammasome leading to IL-1 - IL-17 dependent lung inflammation, fibrosis and emphysema. The inflammasomes, IL-1β and IL-17 are critical in injury induced inflammatory lung pathology and represent therapeutic targets for future medicines.