Repeatability of the Evaluation of Perception of Dyspnea in Normal Subjects Assessed Through Inspiratory Resistive Loads



Andréia K Fernandes*, 1, Bruna Ziegler 2, Glauco L Konzen 2, Paulo R.S Sanches 3, André F Müller 3, Rosemary P Pereira 4, Paulo de Tarso R Dalcin 4
1 Programa de Pós-Graduação em Ciências Pneumológicas, Universidade Federal do Rio Grande do Sul (UFRGS), Brazil
2 Programa de Pós-Graduação em Ciências Pneumológicas, UFRGS, Brazil
3 Serviço de Engenharia Biomédica do Hospital de Clínicas de Porto Alegre (HCPA), Brazil
4 Faculdade de Medicina, UFRGS; Serviço de Pneumologia, HCPA, Brazil


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© Fernandes et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Travessa Miranda e Castro, 70/402, Bairro Santana, Porto Alegre, RS, CEP: 90040-280, Brazil; Tel: +55 51 3508-6333; E-mail: andreiakist@hotmail.com


Abstract

Purpose:

Study the repeatability of the evaluation of the perception of dyspnea using an inspiratory resistive loading system in healthy subjects.

Methods:

We designed a cross sectional study conducted in individuals aged 18 years and older. Perception of dyspnea was assessed using an inspiratory resistive load system. Dyspnea was assessed during ventilation at rest and at increasing resistive loads (0.6, 6.7, 15, 25, 46.7, 67, 78 and returning to 0.6 cm H2O/L/s). After breathing in at each level of resistive load for two minutes, the subject rated the dyspnea using the Borg scale. Subjects were tested twice (intervals from 2 to 7 days).

Results:

Testing included 16 Caucasian individuals (8 male and 8 female, mean age: 36 years). The median scores for dyspnea rating in the first test were 0 at resting ventilation and 0, 2, 3, 4, 5, 7, 7 and 1 point, respectively, with increasing loads. The median scores in the second test were 0 at resting and 0, 0, 2, 2, 3, 4, 4 and 0.5 points, respectively. The intra-class correlation coefficient was 0.57, 0.80, 0.74, 0.80, 0.83, 0.86, 0.91, and 0.92 for each resistive load, respectively. In a generalized linear model analysis, there was a statistically significant difference between the levels of resistive loads (p<0.001) and between tests (p=0.003). Dyspnea scores were significantly lower in the second test.

Conclusion:

The agreement between the two tests of the perception of dyspnea was only moderate and dyspnea scores were lower in the second test. These findings suggest a learning effect or an effect that could be at least partly attributed to desensitization of dyspnea sensation in the brain.

Keywords: Dyspnea, inspiratory resistive loading system, normal subjects, perception, repeatability..