| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Topical Review |
1 The John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, 53726-2368, USA
Sleep unmasks a highly sensitive hypocapnia-induced apnoeic threshold, whereby apnoea is initiated by small transient reductions in arterial CO2 pressure (PaCO2) below eupnoea and respiratory rhythm is not restored until PaCO2 has risen significantly above eupnoeic levels. We propose that the ‘CO2 reserve’ (i.e. the difference in PaCO2 between eupnoea and the apnoeic threshold (AT)), when combined with ‘plant gain’ (or the ventilatory increase required for a given reduction in PaCO2) and ‘controller gain’ (ventilatory responsiveness to CO2 above eupnoea) are the key determinants of breathing instability in sleep. The CO2 reserve varies inversely with both plant gain and the slope of the ventilatory response to reduced CO2 below eupnoea; it is highly labile in non-random eye movement (NREM) sleep. With many types of increases or decreases in background ventilatory drive and PaCO2, the slope of the ventilatory response to reduced PaCO2 below eupnoea remains unchanged from control. Thus, the CO2 reserve varies inversely with plant gain, i.e. it is widened with hyperventilation and narrowed with hypoventilation, regardless of the stimulus and whether it acts primarily at the peripheral or central chemoreceptors. However, there are notable exceptions, such as hypoxia, heart failure, or increased pulmonary vascular pressures, which all increase the slope of the CO2 response below eupnoea and narrow the CO2 reserve despite an accompanying hyperventilation and reduced plant gain. Finally, we review growing evidence that chemoreceptor-induced instability in respiratory motor output during sleep contributes significantly to the major clinical problem of cyclical obstructive sleep apnoea.
(Received 21 July 2004;
accepted after revision 22 July 2004;
first published online 29 July 2004)
Corresponding author J. A. Dempsey: The John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, 53726-2368, USA. Email: jdempsey{at}wisc.edu
This article has been cited by other articles:
|
|
 |
|
  I. Szollosi, B. R. Thompson, H. Krum, D. M. Kaye, and M. T. Naughton Impaired Pulmonary Diffusing Capacity and Hypoxia in Heart Failure Correlates With Central Sleep Apnea Severity Chest, July 1, 2008; 134(1): 67 - 72. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. P. Patil, H. Schneider, A. R. Schwartz, and P. L. Smith Adult Obstructive Sleep Apnea: Pathophysiology and Diagnosis Chest, July 1, 2007; 132(1): 325 - 337. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. R. Casey, K. O. Cantillo, and L. K. Brown Sleep-Related Hypoventilation/Hypoxemic Syndromes Chest, June 1, 2007; 131(6): 1936 - 1948. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. H. Manisty, K. Willson, R. Wensel, Z. I. Whinnett, J. E. Davies, W. L. G. Oldfield, J. Mayet, and D. P. Francis Development of respiratory control instability in heart failure: a novel approach to dissect the pathophysiological mechanisms J. Physiol., November 15, 2006; 577(1): 387 - 401. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Beecroft, J. Duffin, A. Pierratos, C. T. Chan, P. McFarlane, and P. J. Hanly Enhanced chemo-responsiveness in patients with sleep apnoea and end-stage renal disease Eur. Respir. J., July 1, 2006; 28(1): 151 - 158. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. S. Cherniack and G. S. Longobardo Mathematical models of periodic breathing and their usefulness in understanding cardiovascular and respiratory disorders Exp Physiol, March 1, 2006; 91(2): 295 - 305. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. Caples, R. Wolk, and V. K. Somers Influence of cardiac function and failure on sleep-disordered breathing: evidence for a causative role J Appl Physiol, December 1, 2005; 99(6): 2433 - 2439. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Thomson, M. J. Morrell, J. J. Cordingley, and S. J. Semple Ventilation is unstable during drowsiness before sleep onset J Appl Physiol, November 1, 2005; 99(5): 2036 - 2044. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. G. Johnson and D. C. Johnson Bilevel Positive Airway Pressure Worsens Central Apneas During Sleep Chest, October 1, 2005; 128(4): 2141 - 2150. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. L. Knaggs and G. B. Drummond Randomized comparison of three methods of induction of anaesthesia with sevoflurane Br. J. Anaesth., August 1, 2005; 95(2): 178 - 182. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Wiemann, S. Frede, D. Bingmann, P. Kiwull, and H. Kiwull-Schone Sodium/Proton Exchanger 3 in the Medulla Oblongata and Set Point of Breathing Control Am. J. Respir. Crit. Care Med., July 15, 2005; 172(2): 244 - 249. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Kinkead, R. Gulemetova, and A. Bairam Neonatal maternal separation enhances phrenic responses to hypoxia and carotid sinus nerve stimulation in the adult anesthetized rat J Appl Physiol, July 1, 2005; 99(1): 189 - 196. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. H. Wilkinson, K.-L. Sia, E. M. Skuza, V. Brodecky, and P. J. Berger Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb J Appl Physiol, February 1, 2005; 98(2): 437 - 446. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Dempsey Crossing the apnoeic threshold: causes and consequences Exp Physiol, January 1, 2005; 90(1): 13 - 24. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
