Document Detail

Theophylline increases oxygen consumption during inspiratory resistive loading.
MedLine Citation:
PMID:  7697222     Owner:  NLM     Status:  MEDLINE    
The effect of theophylline on diaphragmatic blood flow (Qdi) and oxygen consumption (VO2di) was studied in eight lightly anesthetized dogs during quiet breathing and inspiratory resistive loading. Qdi was determined with the radioactive microsphere tracer technique, and VO2di was calculated as the product of Qdi and the diaphragmatic arterio-venous oxygen difference. During quiet breathing, theophylline increased minute ventilation (9.3 +/- 1.7 versus 5.1 +/- 0.4 L/min), mean inspiratory flow (547 +/- 60 versus 378 +/- 56 ml/s), and duty cycle (0.270 +/- 0.042 versus 0.192 +/- 0.024) but did not significantly alter Qdi or VO2di. Conversely, Qdi increased significantly during loaded breathing compared with quiet breathing (37 +/- 4 versus 27 +/- 3 ml/100 g/min) and was further increased by theophylline (45 +/- 7 ml/100 g/min). Theophylline did not alter the tension-time index of the diaphragm (TTdi) during inspiratory resistive loading (0.054 +/- 0.006 versus 0.056 +/- 0.004, p NS) but resulted in a disproportionate and significant increase in VO2di (2.66 +/- 0.53 versus 1.78 +/- 0.26 ml/100 g/min). Similarly, total-body oxygen consumption (VO2TB) during inspiratory loading increased significantly after theophylline (24%), but the tension-time index of the inspiratory muscles (TTi), a measure of the total respiratory load, was unchanged. We conclude that theophylline significantly increases VO2di and VO2TB at the same TTdi and TTi during resistive loading. This enhanced energy expenditure needs consideration in the clinical management of pulmonary disorders that increase the work of breathing.
S Janssens; E Derom; J Vanhaecke; M Decramer
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  151     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1995 Apr 
Date Detail:
Created Date:  1995-05-04     Completed Date:  1995-05-04     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:  1000-5     Citation Subset:  AIM; IM    
Respiratory Muscle Research Unit, University of Leuven, Belgium.
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MeSH Terms
Diaphragm / blood supply*
Lung Diseases / physiopathology
Muscle Contraction / drug effects*
Oxygen Consumption / drug effects*
Regional Blood Flow / drug effects
Theophylline / pharmacology*
Work of Breathing
Reg. No./Substance:

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