Respiratory muscles's thermographic analysis in asthmatic youth with and without bronchospasm induced by eucapnic...

To compare the thermographic pattern of regions of interest (ROI) of respiratory muscles in young asthmatics with and without bronchospasm induced by eucapnic voluntary hyperpnea (EVH).

Cross-sectional study carried out with 55 young (55% male and 45% females) aged 12.5 ± 3.3 years, divided in nine nonasthmatics, 22 asthmatics without exercise-induced bronchospasm compatible response (EIB-cr) and 24 asthmatics with EIB-cr. The diagnosis of EIB was given to subjects with a fall in forced expiratory volume in the first second (FEV₁) ≥ 10% compared to baseline. Thermographic recordings of respiratory muscles were delimited in ROI of the sternocleidomastoid (SCM), pectoral, and rectus abdominis intention area. Thermal captures and FEV₁ were taken before and 5, 10, 15 and 30 min after EVH.

Twenty-four (52.1%) of asthmatics had EIB-cr. There was a decrease in temperature at 10 min after EVH test in the SCM, pectoral and rectus abdominis ROIs in all groups (both with p < 0.05). There was a decrease in temperature (% basal) in asthmatic with EIB-cr compared to nonasthmatics in the rectus abdominis area (p < 0.05).

There was a decrease in temperature in the ROIs of different muscle groups, especially in asthmatics. The greater drop in FEV₁ observed in individuals with EIB-cr was initially associated with a decrease in skin temperature, with a difference between the nonasthmatics in the abdominal muscle area. It is likely that this decrease in temperature occurred due to a temporary displacement of blood flow to the most used muscle groups, with a decrease in the region of the skin evaluated in the thermography.