Respiratory drive during carbachol challenge in allergic sheep.
Diaphragmatic activity is the standard assessment of respiratory neural output but is difficult to measure and cannot be used for long-term clinical monitoring. The tidal breathing minute ventilation (V') and mean inspiratory flow (VT/tI) reflect respiratory drive and can be monitored non-invasively using respiratory inductive plethysmography (RIP). Recent findings indicate that peak inspiratory acceleration (PIA) correlates to diaphragmatic activity during CO2 rebreathing in piglets. The aim of the present study was to assess whether tidal breathing peak inspiratory acceleration reflects respiratory drive during carbachol challenge. Aerosolized carbachol was administered to 15 allergic sheep until pulmonary resistance increased by at least 400%. After threshold dose, slight increases in V' and VT/tI were seen (8 and 5%, respectively; P=NS), while PIA increased by 30% (P<0.05). The change in PIA was closely correlated to changes in V'[bar over] and VT/tI (r=0.73, P<0.01 and r=0.88, P<0.001, respectively). In conclusion, peak inspiratory acceleration reflected respiratory drive during bronchoprovocation. Further, this new measure of drive has the potential to accurately estimate drive in chronic obstructive lung disease where intrinsic positive end expiratory pressure prevents accurate selection of beginning inspiration necessary for computation of, e.g. VT/tI.
Strömberg
T
T
Department of Biomedical Engineering, Linköping University, Linköping, Sweden.
Adams
J
J
Abraham
W
W
Sackner
M
M
D000818:Animals; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D006967:Hypersensitivity / Q000503:physiopathology*; D008176:Lung Volume Measurements; D010991:Plethysmography; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology*; D012756:Sheep; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology
D018679:Cholinergic Agonists; D002217:Carbachol