The pulmonary effects of intravenous adenosine in asthmatic subjects

BACKGROUND: We have shown that intravenous adenosine in normal subjects does not cause bronchospasm, but causes dyspnea, most likely by an effect on vagal C fibers in the lungs [Burki et al. J Appl Physiol 2005; 98:180-5]. Since airways inflammation and bronchial hyperreactivity are features of asthma, it is possible that intravenous adenosine may be associated with an increased intensity of dyspnea, and may cause bronchospasm, as noted anecdotally in previous reports. METHODS: We compared the effects of placebo and 10 mg intravenous adenosine, in 6 normal and 6 asthmatic subjects. RESULTS: Placebo injection had no significant (p > 0.05) effect on the forced expiratory spirogram, heart rate, minute ventilation (Ve), or respiratory sensation. Similarly, adenosine injection caused no significant changes (p > 0.05) in the forced expiratory spirogram; however, there was a rapid development of dyspnea as signified visually on a modified Borg scale, and a significant (p < 0.05) tachycardia in each subject (Asthmatics +18%, Normals + 34%), and a significant (p < 0.05) increase in Ve (Asthmatics +93%, Normals +130%). The intensity of dyspnea was significantly greater (p < 0.05) in the asthmatic subjects. CONCLUSION: These data indicate that intravenous adenosine does not cause bronchospasm in asthmatic subjects, and supports the concept that adenosine-induced dyspnea is most likely secondary to stimulation of vagal C fibers in the lungs. The increased intensity of adenosine-induced dyspnea in the asthmatic subjects suggests that airways inflammation may have sensitized the vagal C fibers

Avaliação da percepção da dispneia através de sistema de cargas resistivas inspiratórias em indivíduos asmáticos

Introdução: A asma é um problema de saúde pública responsável por alto custo financeiro ao Sistema de Saúde pública, com cerca de 350.000 internações ao ano, sendo a quarta causa de hospitalização no Brasil. Sua prevalência é de cerca de 20% na população brasileira. Dentre os critérios clínicos para o diagnóstico da doença está a dispneia, sintoma cardinal de doenças cardiorrespiratórias caracterizada pela sensação subjetiva de desconforto respiratório, que sofre diferenciação de acordo com influência de múltiplos fatores, os quais determinam sua intensidade, como fatores emocionais e comportamentais. O sistema de cargas resistivas respiratórias vem sendo validado por profissionais da saúde com o objetivo de avaliar e melhorar a função respiratória em indivíduos com condições respiratórias comprometidas. Objetivo: Avaliar o grau de percepção da dispneia em pacientes asmáticos e como o sistema de cargas resistivas respiratórias vem sendo validado por profissionais da saúde. Método: Caracteriza-se como revisão sistemática de literatura, conduzida por meio do Guideline Checklist PRISMA 2020. A pesquisa foi realizada por meio da base de dados PubMed, Scielo e Cochrane, foram utilizadas as seguintes palavras-chaves isoladas ou em combinação entre si, utilizando os operadores booleanos ―AND‖ e ―OR‖: ―Doenças Respiratórias‖, ―Dispneia‖, ―Doenças cardiorrespiratórias‖, ―Asma‖ e ―Cargas Resistivas‖, em português ou inglês. Foram encontradas 93 (noventa e três) referências bibliográficas e, seguindo os critérios de inclusão e exclusão definidos, apenas 35 (trinta e cinco) foram incluídas na pesquisa. Conclusões: a percepção de dispneia pode estar reduzida em alguns pacientes asmáticos, e em geral pode estar associada ao aumento do nível de opioides e redução da quimiossensibilidade ou hipóxia. Em contexto geral, a dispneia é percebida de forma semelhante entre asmáticos e indivíduos normais.Introduction: Asthma is a public health problem responsible for high financial costs to the Public Health System, with about 350,000 hospitalizations per year, and it is the fourth leading cause of hospitalization in Brazil. Its prevalence is about 20% in the Brazilian population. Among the clinical criteria for the diagnosis of the disease is dyspnea, a cardinal symptom of cardiorespiratory diseases characterized by the subjective sensation of respiratory distress, which is differentiated according to the influence of multiple factors, which determine its intensity, such as emotional and behavioral factors. The respiratory resistive load system has been validated by health professionals with the objective of evaluating and improving respiratory function in individuals with compromised respiratory conditions. Objective: To evaluate the degree of perception of dyspnea in asthmatic patients and how the respiratory resistive load system has been validated by health professionals. Method: This is a systematic literature review, conducted using the PRISMA 2020 Guideline Checklist. The search was conducted using the PubMed, Scielo and Cochrane databases, and the following keywords were used alone or in combination, using the Boolean operators "AND" and "OR": "Respiratory Diseases", "Dyspnea", "Cardiorespiratory Diseases", "Asthma" and "Resistive Loads", in Portuguese or English. Ninety-three (93) references were found, and following the defined inclusion and exclusion criteria, only thirty-five (35) were included in the research. Conclusions: The perception of dyspnea may be reduced in some asthmatic patients, and in general it may be associated with increased opioid levels and reduced chemosensitivity or hypoxia. In general context, dyspnea is perceived similarly between asthmatics and normal individuals