Adaptation of ventilation to 'buffeting' in vehicles.
OBJECTIVE
Short exposures to buffeting in a vehicle driving over rough terrain induce an increase in the frequency of respiration resulting in hyperpnoea and hypocapnia. The present study investigates the adaptation to buffeting-induced hyperpnoea.


METHODS
We monitored ventilation and cardiovascular function in nine healthy young adults prior to, throughout and post a 30 minute simulation of buffeting.


RESULTS
All subjects had a consistent elevation of respiratory frequency throughout motion. End-tidal CO(2) decreased during the first 5 minutes of buffeting due to a transient increase in minute ventilation. Elevation of respiratory frequency was facilitated by shortening of inspiration without change in expiratory time. Tidal volume was maintained which resulted in an increase in mean inspiratory flow during buffeting. At later stages of motion there was a partial return to normal for mean inspiratory flow, minute ventilation and end-tidal CO(2)because of a slight reduction in tidal volume whilst inspiratory time remained shortened. Salivary cortisol levels were unaffected by motion, suggesting that the hyperpnoea was not secondary to non-specific stress.


CONCLUSIONS
The cause of elevated respiratory frequency during buffeting could be due to mechanical action on the torso, vestibular-respiratory drive or a protective reinforcement of the torso.
Green
David Andrew
DA
Division of Neuroscience and Psychological Medicine, Imperial College London, Charing Cross Hospital Campus, London, W6 8RF, UK.
Golding
John Foster
JF
Aulakh
Mandip
M
Mandip
Aulukh
A
Faldon
Mary Catherine
MC
Murphy
Kevin Graeme
KG
Bronstein
Adolfo Miguel
AM
Gresty
Michael Andrew
MA
D000222:Adaptation, Physiological; D000328:Adult; D001334:Automobile Driving; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D045853:Exhalation / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D006935:Hypercapnia / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D016857:Hypocapnia / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D001239:Inhalation / Q000502:physiology; D008297:Male; D018986:Motor Vehicles; D012123:Pulmonary Ventilation / Q000502:physiology*
D002245:Carbon Dioxide; D006854:Hydrocortisone
Am J Physiol Regul Integr Comp Physiol. 2002 Mar;282(3):R689-94
11832387
J Appl Physiol (1985). 2002 Dec;93(6):2044-52
12391116
Clin Auton Res. 2006 Aug;16(4):281-5
16832596
Clin Chem. 2003 Jan;49(1):203-4
12507989
J Appl Physiol (1985). 2004 Oct;97(4):1219-26
15155713
Acta Physiol Scand. 1992 Apr;144(4):409-18
1534959
N Engl J Med. 2002 Jul 4;347(1):43-53
12097540
Aviat Space Environ Med. 2003 Mar;74(3):220-7
12650268
J Psychosom Res. 2007 May;62(5):595-6
17467415
Aviat Space Environ Med. 1976 Jan;47(1):9-16
1247443
Respir Physiol Neurobiol. 2007 Nov 15;159(2):115-26
17660051
Neurosci Lett. 2001 Jan 26;298(1):17-20
11154825
Brain. 1997 Sep;120 ( Pt 9):1659-73
9313647
Anesthesiology. 1993 Feb;78(2):251-9
8439019
Clin Exp Pharmacol Physiol. 2002 Jan-Feb;29(1-2):112-7
11906468