Temperatura do ar exalado, um novo biomarcador no controle da asma: um estudo piloto

Abstract

Objective: To evaluate whether the exhaled breath temperature (EBT), measured by a noninvasive method, is an effective means of monitoring patients with uncontrolled asthma. Methods: A pilot study comprising nine patients (seven women and two men; mean age: 39 years) diagnosed with asthma at least one year prior to the beginning of the study and not having been under maintenance therapy for the last three months. In the first visit, the patients underwent spirometry and measurement of EBT. The patients were then instructed to use inhaled budesonide/formoterol (200/6 µg) every 12 h for six weeks. In addition, the patients with severe asthma (FEV 1 < 60% of predicted) were instructed to use oral prednisolone (40 mg/day) for five days. After six weeks, the patients underwent the same tests. Results: All of the patients reported an improvement in the symptoms of asthma, as confirmed by a statistically significant increase in FEV 1 from the first to the second visit (mean, 56.1% vs. 88.7% of predicted; p < 0.05). Five patients used oral prednisolone for the first five days of the treatment period. Six patients used additional doses of inhaled budesonide/formoterol (mean duration, 2.5 weeks). The EBT decreased significantly from the first to the second visit (mean EBT: 35.1°C vs. 34.1°C; p < 0.05). Conclusions: Uncontrolled asthma, especially during exacerbations, is followed by an increase in EBT, which decreases after appropriate asthma control, as demonstrated by an increase in FEV 1 and an improvement of the reported symptoms. These preliminary results suggest that EBT can be used as a parameter for the assessment of asthma control.Keywords: Asthma; Biomarkers, pharmacological; Hydroxycorticosteroids. ResumoObjetivo: Avaliar se a temperatura do ar exalado (TAE), medida por um método não invasivo, é efetiva no monitoramento de pacientes com asma não controlada. Métodos: Estudo piloto com nove pacientes (sete mulheres e dois homens; média de idade: 39 anos) com diagnóstico de asma por pelo menos um ano e sem uso de tratamento de manutenção por pelo menos três meses antes do início do estudo. Na primeira visita, os pacientes foram submetidos à espirometria e à medida da TAE. Todos os pacientes foram orientados a iniciar tratamento com budesonida/formoterol (200/6 µg) inalatório a cada 12 h por seis semanas. Além disso, os pacientes com asma grave (VEF 1 < 60% do previsto) foram orientados a utilizar prednisolona oral (40 mg/dia) por cinco dias. Após seis semanas, os pacientes foram submetidos aos mesmos testes. Resultados: Todos os pacientes relataram melhora dos sintomas de asma; confirmada por um aumento significativo de VEF 1 da primeira para a segunda visita (média de VEF 1 : 56,1% vs. 88,7% do previsto; p < 0,05). Cinco pacientes utilizaram prednisolona oral, mas somente nos cinco dias iniciais do tratamento. Seis pacientes utilizaram doses extras da medicação inalatória (média de tempo de uso de medicação adicional = 2,5 semanas). Houve uma diminuição significativa da TAE entre os momentos de avaliação ...

Usefulness of the Exhaled Breath Temperature Plateau in Asthma Patients

“…This increase could be measured in exhaled air [2,3,4,5]. EBT has also been related to markers of inflammation such as Fe NO levels, eosinophil counts, forced expiratory volume in 1 s (FEV 1 ), and bronchial challenge tests [1,6,7,8,9], but results to date have been contradictory. Furthermore, most studies have been performed in small, pediatric populations with varying equipment and measurements.…”

A survey of recently published cardiovascular, hematological and pneumological original articles in the Brazilian scientific press

“…Their results suggest that a significant proportion of asthma patients have a poor perception of dyspnea. Melo et al64 evaluated whether the exhaled breath temperature, measured by a noninvasive method, is an effective means of monitoring patients with uncontrolled asthma and conclude that uncontrolled asthma, especially during exacerbations, is followed by an increase in exhaled breath temperature, which decreases after appropriate asthma control. Lima et al65 endeavored to determine whether children and adolescents are able to perceive acute exercise-induced bronchoconstriction (EIB), as well as to measure the discriminatory power of a word labeled visual analog dyspnea scale in relation to the intensity of the FM.…”

Requirements for Supporting Diagnostic Equipment of Respiration Process in Humans

“…The air exhaled by humans has nearly 95% humidity and a temperature of about 34.8 °C [ 53 , 54 , 55 , 56 , 57 ]. The relative humidity of the exhaled air depends very much on the temperature.…”