Faculty Collaboration Database

Changes in breathing when switching from nares to tracheostomy breathing in awake ponies. J Appl Physiol (1985) 1985 Oct;59(4):1214-21

Date

10/01/1985

Pubmed ID

4055600

DOI

10.1152/jappl.1985.59.4.1214

Scopus ID

2-s2.0-0022405409 (requires institutional sign-in at Scopus site)   7 Citations

Abstract

We assessed the consequences of respiratory unloading associated with tracheostomy breathing (TBr). Three normal and three carotid body-denervated (CBD) ponies were prepared with chronic tracheostomies that at rest reduced physiological dead space (VD) from 483 +/- 60 to 255 +/- 30 ml and lung resistance from 1.5 +/- 0.14 to 0.5 +/- 0.07 cmH2O . l-1 . s. At rest and during steady-state mild-to-heavy exercise arterial PCO2 (PaCO2) was approximately 1 Torr higher during nares breathing (NBr) than during TBr. Pulmonary ventilation and tidal volume (VT) were greater and alveolar ventilation was less during NBr than TBr. Breathing frequency (f) did not differ between NBr and TBr at rest, but f during exercise was greater during TBr than during NBr. These responses did not differ between normal and CBD ponies. We also assessed the consequences of increasing external VD (300 ml) and resistance (R, 0.3 cmH2O . l-1 . s) by breathing through a tube. At rest and during mild exercise tube breathing caused PaCO2 to transiently increase 2-3 Torr, but 3-5 min later PaCO2 usually was within 1 Torr of control. Tube breathing did not cause f to change. When external R was increased 1 cmH2O . l-1 . s by breathing through a conventional air collection system, f did not change at rest, but during exercise f was lower than during unencumbered breathing. These responses did not differ between normal, CBD, and hilar nerve-denervated ponies, and they did not differ when external VD or R were added at either the nares or tracheostomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Forster HV, Pan LG, Bisgard GE, Flynn C, Hoffer RE

Author

Hubert V. Forster PhD Professor in the Physiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Airway Resistance
Animals
Chemoreceptor Cells
Consciousness
Horses
Lung Compliance
Physical Exertion
Pulmonary Gas Exchange
Pulmonary Stretch Receptors
Respiration
Respiratory Dead Space
Tracheotomy