Articles

Acute and chronic responses of the upper airway to inspiratory loading in healthy awake humans: an MRI study

Author

How S. C, McConnell A. K, Taylor B. J, Romer L. M.

Journal

Respiration Physiology Neurobiology.

Volume

157

Issue ID

'2-3

Page

270-80

Date

2007 August 1.

Keyword

Alternative medicine
Adult
Airway Resistance/physiology*
Breathing Exercises
Female
Humans
Inhalation/physiology*
Magnetic Resonance Imaging*
Male
Mouth Breathing
Respiratory Muscles/physiology
Respiratory Physiology*
Respiratory System/anatomy & histology*
Time Factors
Wakefulness/physiology*

Abstract

We assessed upper airway responses to acute and chronic inspiratory loading. In Experiment I, 11 healthy subjects underwent T(2)-weighted magnetic resonance imaging (MRI) of upper airway dilator muscles (genioglossus and geniohyoid) before and up to 10 min after a single bout of pressure threshold inspiratory muscle training (IMT) at 60% maximal inspiratory mouth pressure (MIP). T(2) values for genioglossus and geniohyoid were increased versus control (p<0.001), suggesting that these airway dilator muscles are activated in response to acute IMT. In Experiment II, nine subjects underwent 2D-Flash sequence MRI of the upper airway during quiet breathing and while performing single inspirations against resistive loads (10%, 30% and 50% MIP); this procedure was repeated after 6 weeks of IMT. Lateral narrowing of the upper airway occurred at all loads, whilst anteroposterior narrowing occurred at the level of the laryngopharynx at loads >  or =30% MIP. Changes in upper airway morphology and narrowing after IMT were undetectable using MRI.

Language

English