Inspiratory Resistive (R) Load Endurance Testing in Normal Healthy Adults: Load compensation, effort sensation and affective perception.

Abstract

Increased respiratory load is a key feature in various respiratory diseases, accompanied by ventilatory compensation, cognitive awareness and affective perception. Loaded breathing can occur from minutes to days requiring the individual to modulate their breathing pattern to maintain alveolar ventilation, minimize work of breathing and minimize aversive load sensations. Increased inspiratory load is associated with cognitive sensation of the load magnitude and affective escape behavior to reduce the aversive perception of loaded breathing. During exacerbations of lung diseases, an individual often must compensate for increased loads that exceed their ability to sustain alveolar ventilation. Yet it is difficult to assess the capacity of an individual to adapt to an increased respiratory load. The aim of this study was to determine the ventilatory and perceptual endurance response to a high magnitude inspiratory R load applied for 10 minutes. It was hypothesized that some individuals would be able to complete the task and other individuals would terminate the task early. It was further hypothesized that early termination of the task would be due to increased aversive affective awareness. Healthy participants were tested while breathing through a non‐rebreathing circuit with an inspiratory load R=50 cmH20/L/s. The individual respired with no‐load for 1 minute, then the load was applied for 10 minutes, followed by 1 minute of no‐load breathing. The subject was instructed that they could terminate the task at any time by removing the mouthpiece. Subjects estimated their perceived load intensity (MEInt) and unpleasantness (MEUn) every minute. Fear (MEF) was estimated before and after the load trial. Two of six subjects terminated the trial early. The ventilatory load pattern for all subjects was a load dependent increased maximum inspiratory pressure, decreased airflow, increased inspiratory duration and unchanged expiratory duration, increased total breath time, increased inspiratory volume, unchanged minute ventilation, PCO2 and PO2. The MEInt increased with the onset of the load, was constant throughout the task and was the same for individuals that completed and stopped the task. MEUn increased with the load onset with greater MEUn for subjects that stopped early. The individuals that stopped early had equal MEF at task onset but much greater MEF when the task stopped. The results suggest that inspiratory R50 endurance capacity is decreased in individuals with greater negative affective responses to high magnitude loaded breathing.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.