Document Detail

Effect of resistive loading on variational activity of breathing.
MedLine Citation:
PMID:  9620902     Owner:  NLM     Status:  MEDLINE    
To examine the effect of resistive loading on variational activity of breathing, we studied 18 healthy subjects breathing at rest and with inspiratory resistive loads of 3 and 6 cm H2O/L/s, applied randomly for 1 h each. Compared with resting breathing, a resistive load of 3 cm H2O/L/s decreased the total variational activity of expiratory time (TE) and minute ventilation (V I), whereas a load of 6 cm H2O/L/s increased the total variational activity of inspiratory time (TI). Compared with the load of 3 cm H2O/L/s, the load of 6 cm H2O/L/s increased total variational activity of tidal volume (VT), TI, TE, and V I. Partitioning of the total variational activity revealed that these alterations were due to changes in the random uncorrelated fraction. Compared with rest, both the resistive loads of 3 and 6 cm H2O/L/s increased the number of breath lags displaying significant serial correlations ("short-term memory") of TI. Compared with rest, the load of 3 cm H2O/L/s increased the autocorrelation coefficient at a lag of one breath for VT and the load of 6 cm H2O/L/s increased the correlated fraction of variational activity of VT. Thus, three measures of correlated behavior-autocorrelation coefficient at a lag of 1 breath, "short-term memory," and the correlated fraction of total variational activity- increased with loading. In conclusion, resistive loading changed total variational activity according to the size of the load: the random fraction decreased with the smaller load but increased with the larger load; in contrast, correlated behavior increased with both loads. The different behaviors of random and correlated variability with loading may reflect different physiologic influences on respiratory control.
T Brack; A Jubran; M J Tobin
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  157     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1998 Jun 
Date Detail:
Created Date:  1998-07-10     Completed Date:  1998-07-10     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1756-63     Citation Subset:  AIM; IM    
Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. Veterans Administration Hospital, Hines, IL 60141, USA.
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MeSH Terms
Airway Resistance*
Carbon Dioxide / physiology
Middle Aged
Respiration / physiology*
Tidal Volume
Reg. No./Substance:
124-38-9/Carbon Dioxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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