Cumulative Effects of Aging and Mechanical Ventilation on In Vitro Diaphragm Function

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Andrew Shanely Ph.D, Associate Professor (Creator)
Appalachian State University (ASU )
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Abstract: Study objective: Unloading the diaphragm, via mechanical ventilation (MV), results in significant diaphragmaticatrophy, contractile dysfunction, and oxidative stress in young adult animals. Since aging increases skeletal musclesusceptibility to atrophy and injury, we tested the hypothesis that MV-induced diaphragmatic contractiledysfunction would be exacerbated in aging rats.Methods: Fisher 344/Brown Norway hybrid rats (4 months old [young] and 30 months old [old]) were assigned toeither control or MV groups. MV rats were anesthetized, tracheostomized, and ventilated with 21% O2 for 12 h.Arterial BP, pH, and blood gas homeostasis were maintained in the MV animals throughout the experimental period. Animals in the control group were acutely anesthetized, and the diaphragms were immediately removed.Muscle strips from the mid-costal diaphragm were removed from each experimental animal, and contractile properties were studied in vitro.Results: Compared to young control animals, aging (old control animals) was associated with a 13% decrease inmaximal isometric tension (24.5 N/cm2 vs 21.3 N/cm2). Although, MV induced similar relative losses (24%) indiaphragmatic isometric tension in both young and old animals receiving MV, the combined effects of aging andMV resulted in a 34% decrement in diaphrag- matic isometric tension compared to young control animals (24.5N/cm2 vs 16.1 N/cm2).Conclusions: These data do not support the hypothesis that aging exacerbates the relative MV-inducedimpairment in diaphragmatic isometric tension. Nonetheless, the additive effects of aging and MV have dramaticeffects on diaphragmatic force reserve. This could exacerbate weaning difficulties in older individuals receivingMV

Additional Information

David S. Criswell, PhD; R. Andrew Shanely, PhD; Jenna J. Betters, MS; Michael J. McKenzie, MS; Jeff E. Sellman, BS; Darin L. Van Gammeren, MA Ed; and Scott K. Powers, PhD (2003) "Cumulative Effects of Aging and Mechanical Ventilation on In Vitro Diaphragm Function" Chest 124: 2302-2308 Version of Record available @ (doi:10.1378/ chest.124.6.2302)
Language: English
Date: 2003
aging, artificial-respiration, contractile-function, diaphragm

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