"Hot stuff": bronchial thermoplasty for asthma

Anesthetic considerations for interventional pulmonary procedures

PURPOSE OF REVIEW

To discuss the anesthetic considerations of various procedures now performed by the interventional pulmonologist. With recent technological advances, many of these procedures represent acceptable alternatives to the invasive surgical procedures. For example, the placement of endobronchial valves can substitute for lung reduction surgery and can greatly reduce the postoperative recovery period. However, many of these complex procedures require anesthesia services. The nature and indication for the procedure as well as the patient's overall health will have an impact on the anesthetic choice.

RECENT FINDINGS

New studies have documented common complications from interventional pulmonology procedures and recent ways to avoid these complications have been suggested. Strategies to avoid obstruction, bleeding, pneumothorax and air embolism are discussed in this article. Potential benefits of high frequency jet ventilation in reducing airway pressures and, perhaps, barotraumas are cited. Novel interventional pulmonary procedures are described.

SUMMARY

As the array of diagnostic and therapeutic pulmonary interventions is expanding, the types of anesthetic techniques and ventilatory modes are varying to fit the procedural requirements. Some pulmonary procedures are best accomplished in the lightly sedated patient, who is breathing spontaneously, whereas procedures that use the working channel of a rigid bronchoscope are better performed in the patient under general anesthesia and mechanical ventilation that often use jet ventilation to minimize respiratory movements.

Bronchial thermoplasty in asthma

Currently available treatments for asthma provide satisfactory control of the disease in most cases. However, a significant number of patients do not respond to such treatments (i.e., do not achieve effective symptom relief). One novel approach to treating asthma is bronchial thermoplasty, in which the airway smooth muscle is specifically and directly treated. This procedure delivers radiofrequency energy to the airways in order to reduce smooth muscle-mediated bronchoconstriction. In this article, we present the thermoplasty technique, summarizing the results of the major randomized clinical trials of the procedure, as well as discussing its mechanisms of action and potential adverse effects. We also propose strategies for the future clinical use of this new treatment.

Interventional bronchoscopy from bench to bedside: new techniques for central and peripheral airway obstruction

This article discusses how basic scientific concepts, based on a greater understanding of airway physiology, support the development and dissemination of multidimensional classification systems for tracheal stenosis, expiratory central airway collapse, and innovative interventional bronchoscopic procedures for patients with asthma and chronic obstructive pulmonary disease.

Extracellular matrix and airway smooth muscle interactions: a target for modulating airway wall remodelling and hyperresponsiveness?

The airway smooth muscle from asthmatic airways produces increased amounts and an altered composition of extracellular matrix proteins. The extracellular matrix can in turn influence the phenotype and function of airway smooth muscle cells, affecting the biochemical, geometric, and mechanical properties of the airway wall. This review provides a brief overview of the current understanding of the biology associated with airway smooth muscle interactions with the extracellular matrix. We present future directions needed for the study of cellular and molecular mechanisms that determine the outcomes of extracellular matrix - airway smooth muscle interactions, and discuss their possible importance as determinants of airway function in asthma.

Airway smooth muscle dynamics: a common pathway of airway obstruction in asthma

Excessive airway obstruction is the cause of symptoms and abnormal lung function in asthma. As airway smooth muscle (ASM) is the effecter controlling airway calibre, it is suspected that dysfunction of ASM contributes to the pathophysiology of asthma. However, the precise role of ASM in the series of events leading to asthmatic symptoms is not clear. It is not certain whether, in asthma, there is a change in the intrinsic properties of ASM, a change in the structure and mechanical properties of the noncontractile components of the airway wall, or a change in the interdependence of the airway wall with the surrounding lung parenchyma. All these potential changes could result from acute or chronic airway inflammation and associated tissue repair and remodelling. Anti-inflammatory therapy, however, does not "cure" asthma, and airway hyperresponsiveness can persist in asthmatics, even in the absence of airway inflammation. This is perhaps because the therapy does not directly address a fundamental abnormality of asthma, that of exaggerated airway narrowing due to excessive shortening of ASM. In the present study, a central role for airway smooth muscle in the pathogenesis of airway hyperresponsiveness in asthma is explored.

Severe asthma in adults: what are the important questions?

The term severe refractory asthma (SRA) in adults applies to patients who remain difficult to control despite extensive re-evaluation of diagnosis and management following an observational period of at least 6 months by a specialist. Factors that influence asthma control should be recognized and adequately addressed prior to confirming the diagnosis of SRA. This report presents statements according to the literature defining SRA in order address the important questions. Phenotyping SRA will improve our understanding of mechanisms, natural history, and prognosis. Female gender, obesity, and smoking are associated with SRA. Atopy is less frequent in SRA, but occupational sensitizers are common inducers of new-onset SRA. Viruses contribute to severe exacerbations and can persist in the airways for long periods. Inflammatory cells are in the airways of the majority of patients with SRA and persist despite steroid therapy. The T(H)2 immune process alone is inadequate to explain SRA. Reduced responsiveness to corticosteroids is common, and epithelial cell and smooth muscle abnormalities are found, contributing to airway narrowing. Large and small airway wall thickening is observed, but parenchymal abnormalities may influence airway limitation. Inhaled corticosteroids and bronchodilators are the mainstay of treatment, but patients with SRA remain uncontrolled, indicating a need for new therapies.