Michael J. Morris

Diagnostic Criteria for the Classification of Vocal Cord Dysfunction

Vocal cord dysfunction (VCD) is a syndrome characterized by paroxysms of glottic obstruction due to true vocal cord adduction resulting in symptoms such as dyspnea and noisy breathing. Since first described as a distinct clinical entity in 1983, VCD has inadvertently become a collective term for a variety of clinical presentations due to glottic disorders. Despite an increased understanding of laryngeal function over the past 25 years, VCD remains a poorly understood and characterized entity. Disparities in the literature regarding etiology, pathophysiology, and management may be due to the historic approach to this patient population. Additionally, disorders clearly not due to paroxysms of true vocal cord adduction, such as laryngomalacia, vocal cord paresis, and CNS causes, need to be differentiated from VCD. Although a psychologic origin for VCD has been established, gastroesophageal reflux disease (GERD), nonspecific airway irritants, and exercise have also been associated with intermittent laryngeal obstruction with dyspnea and noisy breathing. VCD has been repeatedly misdiagnosed as asthma; however, the relationship between asthma and VCD is elusive. There are numerous case reports on VCD, but there is a paucity of prospective studies. Following an in-depth review of the medical literature, this article examines the available retrospective and prospective evidence to present an approach for evaluation of VCD including: (1) evaluation of factors associated with VCD, (2) differential diagnosis of movement disorders of the upper airway, and (3) clinical, spirometric, and endoscopic criteria for the diagnosis.

Respiratory dialysis: reduction in dependence on mechanical ventilation by venovenous extracorporeal CO2 removal.

Objectives: Mechanical ventilation is injurious to the lung. Use of lung-protective strategies may complicate patient management, motivating a search for better lung-replacement approaches. We investigated the ability of a novel extracorporeal venovenous CO2 removal device to reduce minute ventilation while maintaining normocarbia. Design: Prospective animal study. Setting: Government laboratory animal intensive care unit. Subjects: Seven sedated swine. Interventions: Tracheostomy, volume-controlled mechanical ventilation, and 72 hrs of round-the-clock intensive care unit care. A 15-F dual-lumen catheter was inserted in the external jugular vein and connected to the Hemolung, an extracorporeal pump-driven venovenous CO2 removal device. Minute ventilation was reduced, and normocarbia (Paco2 35–45 mm Hg) maintained. Heparinization was maintained at an activated clotting time of 150–180 secs. Measurements and Main Results: Minute ventilation (L/min), CO2 removal by Hemolung (mL/min), Hemolung blood flow, O2 consumption (mL/min), CO2 production by the lung (mL/min), Paco2, and plasma-free hemoglobin (g/dL) were measured at baseline (where applicable), 2 hrs after device insertion, and every 6 hrs thereafter. Minute ventilation was reduced from 5.6 L/min at baseline to 2.6 L/min 2 hrs after device insertion and was maintained at 3 L/min until the end of the study. CO2 removal by Hemolung remained steady over 72 hrs, averaging 72 ± 1.2 mL/min at blood flows of 447 ± 5 mL/min. After insertion, O2 consumption did not change; CO2 production by the lung decreased by 50% and stayed at that level (p < .001). As the arterial PCO2 rose or fell, so did CO2 removal by Hemolung. Plasma-free hemoglobin did not change. Conclusions: Venovenous CO2 removal enabled a 50% reduction in minute ventilation while maintaining normocarbia and may be an effective lung-protective adjunct to mechanical ventilation.

Vocal Cord Dysfunction Etiologies and Treatment

Vocal cord dysfunction, a syndrome of paradoxical inspiratory closure of the vocal cords, is becoming more frequently recognized and diagnosed recently since its initial modern description 30 years ago. Initially described as single case reports, the first case series in 1983 helped to clarify the typical patient and findings of vocal cord dysfunction. Recent investigations have elucidated specific etiologies such as gastroesophageal reflux, exercise, and irritants as causative factors in addition to the numerous associated psychologic factors. Speech therapy and psychotherapy have been used extensively with vocal cord dysfunction patients, but the optimal treatment has yet to be prospectively studied. This manuscript provides a comprehensive review of the reported causative factors and treatments for vocal cord dysfunction.

ERS/ELS/ACCP 2013 international consensus conference nomenclature on inducible laryngeal obstructions

Individuals reporting episodes of breathing problems caused by re-occurring variable airflow obstructions in the larynx have been described in an increasing number of publications, with more than 40 different terms being used without consensus on definitions. This lack of an international consensus on nomenclature is a serious obstacle for the development of the area, as knowledge from different centres cannot be matched, pooled or readily utilised by others. Thus, an international Task Force has been created, led by the European Respiratory Society/European Laryngological Society/American College of Chest Physicians. This review describes the methods used to reach an international consensus on the subject and the resulting nomenclature, the 2013 international consensus conference nomenclature. The condition leading to episodes of feeling like you cannot breathe now has a name: inducible laryngeal obstructions http://ow.ly/OMaNl

Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures (STAMPEDE)

RATIONALE Because of increased levels of airborne particulate matter in Southwest Asia, deployed military personnel are at risk for developing acute and chronic lung diseases. Increased respiratory symptoms are reported, but limited data exist on reported lung diseases. OBJECTIVES To evaluate new respiratory complaints in military personnel returning from Southwest Asia to determine potential etiologies for symptoms. METHODS Returning military personnel underwent a prospective standardized evaluation for deployment-related respiratory symptoms within 6 months of returning to their duty station. MEASUREMENTS AND MAIN RESULTS Prospective standardized evaluation included full pulmonary function testing, high-resolution chest tomography, methacholine challenge testing, and fiberoptic bronchoscopy with bronchoalveolar lavage. Other procedures including lung biopsy were performed if clinically indicated. Fifty patients completed the study procedures. A large percentage (42%) remained undiagnosed, including 12% with normal testing and an isolated increase in lavage neutrophils or lymphocytes. Twenty (40%) patients demonstrated some evidence of airway hyperreactivity to include eight who met asthma criteria and two with findings secondary to gastroesophageal reflux. Four (8%) additional patients had isolated reduced diffusing capacity and the remaining six had other miscellaneous airway disorders. No patients were identified with diffuse parenchymal disease on the basis of computed tomography imaging. A significant number (66%) of this cohort had underlying mental health and sleep disorders. CONCLUSIONS Evaluation of new respiratory symptoms in military personnel after service in Southwest Asia should focus on airway hyperreactivity from exposures to higher levels of ambient particulate matter. These patients may be difficult to diagnose and require close follow-up.

Transitioning the Respiratory Therapy Workforce for 2015 and Beyond

The American Association for Respiratory Care established a task force in late 2007 to identify likely new roles and responsibilities of respiratory therapists (RTs) in the year 2015 and beyond. A series of 3 conferences was held between 2008 and 2010. The first task force conference affirmed that the healthcare system is in the process of dramatic change, driven by the need to improve health while decreasing costs and improving quality. This will be facilitated by application of evidence-based care, prevention and management of disease, and closely integrated interdisciplinary care teams. The second task force conference identified specific competencies needed to assure safe and effective execution of RT roles and responsibilities in the future. The third task force conference was charged with creating plans to change the professional education process so that RTs are able to achieve the needed skills, attitudes, and competencies identified in the previous conferences. Transition plans were developed by participants after review and discussion of the outcomes of the first two conferences and 1,011 survey responses from RT department managers and RT education program directors. This is a report of the recommendations of the third task force conference held July 12-14, 2010, on Marco Island, Florida. The participants, who represented groups concerned with RT education, licensure, and practice, proposed, discussed, and accepted that to be successful in the future a baccalaureate degree must be the minimum entry level for respiratory care practice. Also accepted was the recommendation that the Certified Respiratory Therapist examination be retired, and instead, passing of the Registered Respiratory Therapist examination will be required for beginning clinical practice. A date of 2020 for achieving these changes was proposed, debated, and accepted. Recommendations were approved requesting resources be provided to help RT education programs, existing RT workforce, and state societies work through the issues raised by these changes.

Comparison of airway pressure release ventilation to conventional mechanical ventilation in the early management of smoke inhalation injury in swine.

Objective:The role of airway pressure release ventilation in the management of early smoke inhalation injury has not been studied. We compared the effects of airway pressure release ventilation and conventional mechanical ventilation on oxygenation in a porcine model of acute respiratory distress syndrome induced by wood smoke inhalation. Design:Prospective animal study. Setting:Government laboratory animal intensive care unit. Patients:Thirty-three Yorkshire pigs. Interventions:Smoke inhalation injury. Measurements and Main Results:Anesthetized female Yorkshire pigs (n = 33) inhaled room-temperature pine-bark smoke. Before injury, the pigs were randomized to receive conventional mechanical ventilation (n = 15) or airway pressure release ventilation (n = 12) for 48 hrs after smoke inhalation. As acute respiratory distress syndrome developed (PaO2/Fio2 ratio <200), plateau pressures were limited to <35 cm H2O. Six uninjured pigs received conventional mechanical ventilation for 48 hrs and served as time controls. Changes in PaO2/Fio2 ratio, tidal volume, respiratory rate, mean airway pressure, plateau pressure, and hemodynamic variables were recorded. Survival was assessed using Kaplan-Meier analysis. PaO2/Fio2 ratio was lower in airway pressure release ventilation vs. conventional mechanical ventilation pigs at 12, 18, and 24 hrs (p < .05) but not at 48 hrs. Tidal volumes were lower in conventional mechanical ventilation animals between 30 and 48 hrs post injury (p < .05). Respiratory rates were lower in airway pressure release ventilation at 24, 42, and 48 hrs (p < .05). Mean airway pressures were higher in airway pressure release ventilation animals between 6 and 48 hrs (p < .05). There was no difference in plateau pressures, hemodynamic variables, or survival between conventional mechanical ventilation and airway pressure release ventilation pigs. Conclusions:In this model of acute respiratory distress syndrome caused by severe smoke inhalation in swine, airway pressure release ventilation-treated animals developed acute respiratory distress syndrome faster than conventional mechanical ventilation-treated animals, showing a lower PaO2/Fio2 ratio at 12, 18, and 24 hrs after injury. At other time points, PaO2/Fio2 ratio was not different between conventional mechanical ventilation and airway pressure release ventilation.

Inflammatory mediators in smoke inhalation injury.

Smoke inhalation occurs in 10% to 30% of patients admitted to burn centers, and increases mortality by a maximum of 20% over that predicted by age and extent of cutaneous burn alone. Pneumonia in these patients then further increases mortality by a maximum of 40%. While one estimate suggested that 75% of deaths following burn injury may be accounted for by inhalation injury, more recent cohort studies have suggested there is a decreasing mortality attributable to inhalation injury. As part of understanding and improving outcomes from burn injuries, the pathophysiology and inflammatory processes involved in smoke inhalation injury has been extensively investigated in animal models. This review will emphasize the inflammatory pathways involved in inhalation injury, and targeted methods used to treat this injury in both experimental and human models.

A computational study of the respiratory airflow characteristics in normal and obstructed human airways

Obstructive lung diseases in the lower airways are a leading health concern worldwide. To improve our understanding of the pathophysiology of lower airways, we studied airflow characteristics in the lung between the 8th and the 14th generations using a three-dimensional computational fluid dynamics model, where we compared normal and obstructed airways for a range of breathing conditions. We employed a novel technique based on computing the Pearson׳s correlation coefficient to quantitatively characterize the differences in airflow patterns between the normal and obstructed airways. We found that the airflow patterns demonstrated clear differences between normal and diseased conditions for high expiratory flow rates (>2300ml/s), but not for inspiratory flow rates. Moreover, airflow patterns subjected to filtering demonstrated higher sensitivity than airway resistance for differentiating normal and diseased conditions. Further, we showed that wall shear stresses were not only dependent on breathing rates, but also on the distribution of the obstructed sites in the lung: for the same degree of obstruction and breathing rate, we observed as much as two-fold differences in shear stresses. In contrast to previous studies that suggest increased wall shear stress due to obstructions as a possible damage mechanism for small airways, our model demonstrated that for flow rates corresponding to heavy activities, the wall shear stress in both normal and obstructed airways was <0.3Pa, which is within the physiological limit needed to promote respiratory defense mechanisms. In summary, our model enables the study of airflow characteristics that may be impractical to assess experimentally.

Granulomatous lung masses in an elderly patient with inactive Crohn's disease

This is a case report of a 77-year-old female with Crohns disease manifested by recurrent bowel obstructions, who required surgical resections on two occasions but no further medical treatment. She presented 2 years later with pulmonary infiltrates, hilar adenopathy, and multiple lung masses. Biopsies of the masses demonstrated noncaseating granulomatous inflammation and fibrosis similar to the pathology from her bowel resection. Six months later, these pulmonary lesions partially resolved without therapy. This case illustrates significant pulmonary manifestations of Crohns disease in the absence of active gastrointestinal disease.