Occupational Medicine Model and Asthma Military Recruitment.

Medical evidence hints that asymptomatic recruits with a history of childhood asthma, quiescent since their 13th birthday, are still at risk for adverse changes in their clinical status following unfavorable environmental exposures during military deployment or combat. Asthmatic persons, claiming none or few symptoms, may still manifest airflow obstruction and display biomarkers of airway inflammation even when they are relatively asymptomatic and experience few if any respiratory complaints. The occupational medicine model offers a credible foundation for acknowledging the importance of personal susceptibility in the pathogenesis of military-associated asthma. It is appropriate to re-explore the current military standard for recruits with asymptomatic childhood asthma (≥12 months) not prescribed antiasthma medications. Raising the acceptance age for these recruits may be a consideration. Unfortunately, there is no effectual screening test that recognizes such susceptible soldiers at risk for future asthma attacks. Nevertheless, there is general support for evidence-based, scientifically valid medical screening that judges fitness for military service. Screening tests comprising asthma biomarkers and genetic indices may better verify vulnerable soldiers destined to suffer future asthma reactivation.

Reactive airways dysfunction syndrome and considerations of irritant-induced Asthma.

The Occupational Medicine Forum is prepared by the ACOEM Occupational and Environmental Medical Practice Committee and does not necessarily represent an official ACOEM position. The Forum is intended for health professionals and is not intended to provide medical or legal advice, including illness prevention, diagnosis or treatment, or regulatory compliance. Such advice should be obtained directly from a physician and/or attorney.

Prospective and management: acute nonimmunologic inhalation injuries.

The Occupational Medicine Forum is prepared by the ACOEM Occupational and Environmental Medical Practice Committee and does not necessarily represent an official ACOEM position. The Forum is intended for health professionals and is not intended to provide medical or legal advice, including illness prevention, diagnosis or treatment, or regulatory compliance. Such advice should be obtained directly from a physician and/or attorney.

Perspective on the human cough reflex.

This review dissects the complex human cough reflex and suggests hypotheses about the evolutionary basis for the reflex. A mechanosensory-induced cough reflex conveys through branches of myelinated Aδ nerve fibers is not chemically reactive (i.e., capsaicin, bradykinin); possibly, its evolution is to prevent the harmful effects of aspiration of gastric or particulate contents into the lungs. This became necessary as the larynx moves closer to the opening of the esophagus as human ancestors adapt phonation over olfaction beginning less than 10 million years ago. The second type of cough reflex, a chemosensory type, is carried by unmyelinated C fibers. Supposedly, its origin dates back when prehistoric humans began living in close proximity to each other and were at risk for infectious respiratory diseases or irritant-induced lung injury. The mechanism for the latter type of cough is analogous to induced pain after tissue injury; and, it is controlled by the identical transient receptor potential vanilloid cation channel (TRPV1). The airways do not normally manifest nociceptive pain from a stimulus but the only consistent response that capsaicin and lung inflammation provoke in healthy human airways is cough. TRPA1, another excitatory ion channel, has been referred to as the "irritant receptor" and its activation also induces cough. For both types of cough, the motor responses are identical and via coordinated, precisely-timed and sequential respiratory events orchestrated by complex neuromuscular networking of the diaphragm, chest and abdominal respiratory muscles, the glottis and parts of the brain.

Irritant-induced airway disorders.

Thousands of persons experience accidental high-level irritant exposures each year but most recover and few die. Irritants function differently than allergens because their actions proceed nonspecifically and by nonimmunologic mechanisms. For some individuals, the consequence of a single massive exposure to an irritant, gas, vapor or fume is persistent airway hyperresponsiveness and the clinical picture of asthma, referred to as reactive airways dysfunction syndrome (RADS). Repeated irritant exposures may lead to chronic cough and continual airway hyperresponsiveness. Cases of asthma attributed to repeated irritant-exposures may be the result of genetic and/or host factors.

Occupational, environmental, and irritant-induced cough.

Occupational and environmental irritants play a role in the pathogenesis of chronic cough. An irritant is a non-corrosive chemical, which causes a reversible inflammatory change on living tissue by chemical action at the site of contact. The clinical and pathologic spectrum of chemically induced respiratory tract irritation ranges from neurogenically mediated alterations in regional blood flow, mucus secretion, and airway caliber to the initiation of cough. In an evolutionary perspective, two types of cough reflexes were created for different protective purposes, but each type used the same anatomic and physiologic neural and muscular structures. The mechanosensory type evolved as human ancestors adapted phonation over olfaction and the larynx moved in close proximity to the esophageal opening. The chemosensory type evolved to protect against an injured lung from a respiratory tract infection or after inhaling high levels of irritant gases and particulates that accumulated in confined quarters of early times. For this latter type of cough reflex, normally quiescent transient receptor potential (TRP) cation channels TRPV1(vanilloid) and TRPA1 (ankyrin) become activated or hyperactivated after lung injury, with lung inflammation, or in response to chemicals. Although animal and laboratory investigations support the possibility of human TRPpathies, further investigations are essential for the further elucidation of the role of TRP cationic channels in instigating chronic cough in humans.

Diagnosis and management of work-related asthma: American College Of Chest Physicians Consensus Statement.

BACKGROUND: A previous American College of Chest Physicians Consensus Statement on asthma in the workplace was published in 1995. The current Consensus Statement updates the previous one based on additional research that has been published since then, including findings relevant to preventive measures and work-exacerbated asthma (WEA). METHODS: A panel of experts, including allergists, pulmonologists, and occupational medicine physicians, was convened to develop this Consensus Document on the diagnosis and management of work-related asthma (WRA), based in part on a systematic review, that was performed by the University of Alberta/Capital Health Evidence-Based Practice and was supplemented by additional published studies to 2007. RESULTS: The Consensus Document defined WRA to include occupational asthma (ie, asthma induced by sensitizer or irritant work exposures) and WEA (ie, preexisting or concurrent asthma worsened by work factors). The Consensus Document focuses on the diagnosis and management of WRA (including diagnostic tests, and work and compensation issues), as well as preventive measures. WRA should be considered in all individuals with new-onset or worsening asthma, and a careful occupational history should be obtained. Diagnostic tests such as serial peak flow recordings, methacholine challenge tests, immunologic tests, and specific inhalation challenge tests (if available), can increase diagnostic certainty. Since the prognosis is better with early diagnosis and appropriate intervention, effective preventive measures for other workers with exposure should be addressed. CONCLUSIONS: The substantial prevalence of WRA supports consideration of the diagnosis in all who present with new-onset or worsening asthma, followed by appropriate investigations and intervention including consideration of other exposed workers.

Irritant-induced chronic cough: irritant-induced TRPpathy.

This article expands the author's presentation at the First American Cough Conference in New York City, June 8-9, 2007. The results of a scientific literature search and application of personal research findings are included. A new hypothesis to explain irritant-induced cough as a being a dysfunction of the transient receptor potential vanilloid 1 (TRPV1) cation channels located in pulmonary excitable cells is presented. The TRPV1 cation channels regulate cellular transmembrane voltage by raising intracellular Ca(2+) and Na(+) concentrations and depolarizing sensory nerve cells containing C-fibers. The discussion centers on the "capsaicin receptor" (TRPV1) and another important ion channel, TRPA1. The author reviews results of published scientific investigations to support his contention that neural events, initiated by TRPV1 ion channels, lead to a cascade of alterations that progress to a cough endpoint. A potential mechanism to explain chronic cough in conditions where there is repeated or severe irritant-induced airway epithelial injury (e.g., RADS) is through persistent TRPV1 channel activation (e.g., TRPV1pathy) with accumulation of inflammatory mediators, tachykinins, and the release of neurotrophins leading to persistent cough and airway inflammation. The significance of the hypothesis is that, if proven, it may provide new therapeutic approaches for the treatment of chronic cough.

Age does not affect airway pH and ammonia as determined by exhaled breath measurements.

Measurement of airway pH has been used as a diagnostic and monitoring tool in a variety of pulmonary diseases in adults. These diseases occur across a wide age range. Few investigations have addressed the effects of aging on airway pH and ammonia. The aim of this study was to determine whether exhaled breath condensate (EBC) measurements of pH and ammonia differ in older and younger populations of normal subjects. Twenty-three normal younger individuals (median age-24 years) and 25 normal older participants (median age-72 years) were investigated by measuring EBC for pH and ammonia using recommended methodologies. EBC ammonia and pH values were not significantly different between younger and older individuals. Thus, we conclude that EBC ammonia and pH do not appear to be affected by age.

The effects of age on exhaled breath nitric oxide levels.

A variety of factors influence exhaled breath nitric oxide (ENO) but few studies have examined ENO at the extremes of adult age. This investigation explores whether there is a difference in ENO between groups of older and younger individuals. A total of 48 normal subjects consisting of 23 younger (median age - 24 years) and 25 older (median age - 72 years) participants were studied. Carefully defined clinical and spirometric parameters, smoking history, and drug/medication documentation were determined to insure normalcy. Measurements of ENO were made using ATS/ERS recommended methodologies. The older group consistently showed higher ENO concentrations than-the younger subjects; median ENO values were 36.9 and 18.7 ppb, respectively (p < 0.001). The statistical significance held true when adjusting for multiple testing with the Holm method and accounting for outliers and medication usage. ENO levels are significantly higher in a normal older population. Comparing ENO between individuals at the extremes of age may depict differences more decidedly. Whether elevated ENO reflects underlying airway inflammation in older persons remains unanswered. It is possible that the difference in NO concentrations between older and younger groups represents only a marker of past oxidant exposures and holds no clinical significance. Additional investigations are necessary to elucidate the mechanisms and significances of elevated NO levels in the aged.

The spectrum of building-related airway disorders: difficulty in retrospectively diagnosing building-related asthma.

INTRODUCTION: The specific causes and mechanism(s) for asthma occurring among occupants of non-residential buildings with poor indoor air quality are not known, but allergic and nonallergic processes are possible explanations METHODS: Repeated indoor air quality measurements were made while employees were working in a building where cigarette smoking was allowed. Seven of 19 employees who sought medical care from their private physicians because of respiratory complaints received a diagnosis of asthma. Subsequently, 19 symptomatic employees were examined at the University of South Florida (USF) 2 +/- 0.8 months (mean +/- SD) after removal from the building. RESULTS: The first floor of the building, where employee complaints were prevalent, was characterized by markedly reduced outdoor fresh air supply, diminished air circulation to the occupant spaces, and elevated airborne concentrations of formaldehyde. Nineteen workers examined at the USF 2 +/- 0.8 months after leaving the building reported ear, nose, and throat irritation and asthma-like symptoms while working in the building. There was resolution of symptoms in most of the seven employees (37%) with asthma previously diagnosed by their private physician. In fact, 16 of 19 subjects (84%) reported resolution or significant improvement of symptoms. Among 11 persons with symptoms suggesting asthma while working in the building, 4 persons (21%) showed a negative provocative concentration of methacholine producing a 20% fall in FEV1, including two subjects with doctor-diagnosed asthma. CONCLUSIONS: Confirmation of building-related asthma is influenced by time factors and the clinical criteria used for diagnosis. A nonallergic mechanism seems operative in our cases. While considered an example of occupational asthma, building-related asthma is a challenge for the practicing physician to confirm retrospectively.

The physical workload of nursing personnel: association with musculoskeletal discomfort.

Direct care-nursing personnel around the world report high numbers of work-related musculoskeletal disorders. This cross-sectional study examined the association between the performance of high-risk patient-handling tasks and self-reported musculoskeletal discomfort in 113 nursing staff members in a veterans' hospital within the United States. Sixty-two percent of subjects reported a 7-day prevalence of moderately severe musculoskeletal discomfort. There was a significant association between wrist and knee pain and the number of highest-risk patient-handling tasks performed per hour interacting with the load lifted. On units where lifting devices are readily available, musculoskeletal risk may have shifted to the wrist and knee.

Evaluation of the reliability and validity of the University of South Florida Environmental Assessment Questionnaire.

BACKGROUND: The National Institute for Occupational Safety and Health's (NIOSH) National Occupational Research Agenda (NORA), identified "exposure assessment methods" as a priority area for research in occupational medicine. METHODS: The University of South Florida Environmental Assessment Questionnaire (EAQ) describes exposures from the workers point of view. The questionnaire was distributed to a sample of workers drawn from a population of over 3,000 workers employed by a Florida food processing plant. The analysis of the validity was based on 211 subjects and the analysis of the reliability was based on 44 subjects. RESULTS: For the category scores, the sensitivities ranged from 0.67 to 1.0, the specificities ranged from 0.52 to 0.83, the positive predictive values ranged from 0.60 to 1.0, and the negative predictive values ranged from 0.55 to 1.0. All of the weighted kappas for the subcategories were above zero. The Spearman rank-order coefficients were above 0.5 for all of the exposure categories except the mold, plant, and animal exposure category which was 0.49. The correlation coefficient for the questionnaire as a whole was 0.85. CONCLUSIONS: This study showed the EAQ as a whole to be reliable and valid. Gathering valid occupational exposure information with this method was both feasible and economical.

Cockatiel-induced hypersensitivity pneumonitis.

Diagnosing an environmental or occupationally related pulmonary disorder often involves a process of elimination. Unlike commonly diagnosed conditions in other specialties, a cause-and-effect relationship may be implied, yet other factors such as temporality and biologic plausibility are lacking. Our patient was referred with a suspected work-related pulmonary disorder. For several years, she had suffered with dyspnea on exertion and repeated flulike illnesses. She worked at an automobile repair garage that performed a large number of emission tests, and there was concern that her workplace exposures were the cause of her symptoms. After a careful review of her history, physical examination, and laboratory testing, we came to the conclusion that she had hypersensitivity pneumonitis related to pet cockatiels in her home. Clinical points of emphasis include the importance of a complete environmental history and careful auscultation of the chest when performing the physical examination. In addition, we encountered an interesting physical diagnostic clue, a respiratory sound that assisted with the eventual diagnosis.

Occupational asthma.

Preview Patients affected by occupational asthma have respiratory symptoms that may persist for months, years, or even life. Hundreds of substances have been implicated in the disease, and the list is expected to grow. The authors discuss management of this sometimes life-threatening condition and emphasize the importance of environmental controls to prevent future cases.