Respiratory mechanics during methacholine bolus and continuous infusion protocols in asthma model

• Published in: Respiratory physiology & neurobiology Vol. 292; p. 103705
• Main Authors: Vitorasso, Renato Lima, Oliveira, Maria Aparecida, Tavares-de-Lima, Wothan, Moriya, Henrique Takachi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2021
• Subjects: Animals; Asthma; Asthma - chemically induced; Bronchoconstrictor Agents - administration & dosage; Disease Models, Animal; Engineering; Male; Methacholine Chloride - administration & dosage; Mice; Mice, Inbred BALB C; Models, Theoretical; Pharmacology; Pulmonary; Respiratory mechanics; Respiratory Mechanics - drug effects; Engineering; Respiratory mechanics; Pharmacology; Pulmonary; Asthma
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/j.resp.2021.103705

•The MCh administration protocol influences the results of respiratoty mechanics in an asthma model.•Our findings reveal that the bolus protocol better differentiates airway resistance between OVA and control.•The bolus protocol favors a non-linear behavior of the respiratory system during the assessment of respiratory mechanics.•The continuous infusion protocol better differentiates parenchyma-related parameters between OVA and control. Balb/c mice respiratory mechanics was studied in two intravenous methacholine (MCh) protocols: bolus and continuous infusion. The Constant Phase Model (CPM) was used in this study. The harmonic distortion index (kd) was used to assess the respiratory system nonlinearity. The analysis of variance showed difference between groups (OVA vs control) and among doses for both protocols. Bolus protocol posttest: there was a difference between OVA and control at 0.3 and 1 mg/kg doses (p<0.0001 and p<0.001) for Rn. Infusion: there was a difference between OVA and control at 192 μg.kg−1.min−1 dose for Rn, G and H, (p<0.01; p<0.001; p<0.001). An increment was found in kd values near to the observed peak values in bolus protocol. The bolus protocol could better differentiate inflamed and non-inflamed airway resistance, whereas the differences between OVA and control in continuous infusion protocol were associated to airway- and, mainly, parenchyma-related parameters. Moreover, the bolus protocol presented a higher nonlinear degree compared to the infusion protocol.