Initiating oral breathing in response to nasal loading: asthmaticsversushealthy subjects

Abstract

Factors influencing nasal versus oral breathing in asthmatics are not well understood. The current authors hypothesised that asthmatic subjects have enhanced perception of nasal threshold loads, and switch from nasal to oral breathing at a lower load than healthy subjects.In total, 15 mild asthmatic and 20 healthy control subjects breathed nasally via an inspiratory threshold loading device. Nasal loading was progressively increased until subjects switched to oral breathing. Load perception at switching was rated using a Borg scale. Nasal resistance was measured using posterior rhinomanometry. The protocol was repeated before and after nasal decongestant administration in subgroups of 10 healthy control and six asthmatic subjects.Inspiratory nasal resistance was within normal limits for most subjects and was not significantly different between asthmatics and healthy controls. Compared with controls, asthmatics switched to oral breathing at a significantly lower nasal load but rated ''difficulty breathing in'' at the same level. Decongestant significantly lowered nasal resistance but did not change the nasal load initiating switching in either subgroup.Enhanced perception of nasal loading may trigger increased oral breathing in asthmatics, potentially enhancing exposure to nonconditioned inhaled gas and contributing to the occurrence and/or severity of bronchoconstrictive exacerbations.

Respiração bucal e anteriorização da cabeça: efeitos na biomecânica respiratória e na capacidade de exercício em crianças

“…(24) Some studies have assessed cardiorespiratory function in subjects under conditions that induce mouth breathing. (25)(26)(27)(28) Ribeiro & Soares (25) observed that some spirometric indices (FEF 25-75% and maximal voluntary ventilation) were below and decreased cervical lordosis in 30 mouthbreathing children. The results of those studies corroborate those of our study.…”

“…(26) In subjects with asthma, less nasal resistance is required in order to induce mouth breathing, and, when mouth breathing occurs, there is a decrease in pulmonary function and a greater predisposition to bronchial obstruction. (27) Melissant et al (28) induced upper airway obstruction during exercise and found that there were decreases in minute ventilation and CO 2 production. The responses of the subjects included hypoventilation, hypoxia, and hypercapnia.…”

Exercise capacity, respiratory mechanics and posture in mouth breathers

“…A few authors have evaluated cardiorespiratory function in mouth breathing subjects [27][28][29][30] . Ribeiro & Soares 27 found lower than predicted spirometry test values (forced expiratory flow 25%-75%, and maximum voluntary ventilation), characterizing a mostly mild to moderate obstructive type ventilation disorder in mouth breathers.…”

Protective Facemask Impact on Human Thermoregulation: An Overview

“…Nasal and oral respiratory pathways of thermostasis The majority of healthy adults are nasal breathers at resting tidal breathing or light exertion (Niinimaa et al, 1980;Hallani et al, 2008), but changes in the partitioning of the breathing cycle among nasal, oronasal, and oral components can impact the respiratory portion of heat exchange, as well as microclimate (i.e. respirator dead space) heat and moisture content.…”