This Article Full Text Full Text (PDF) Online Supplement All Versions of this Article: 200401-042OCv1 170/6/626    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sassoon, C. S. H. Articles by Caiozzo, V. J. Search for Related Content PubMed PubMed Citation Articles by Sassoon, C. S. H. Articles by Caiozzo, V. J.

Assist–Control Mechanical Ventilation Attenuates Ventilator-induced Diaphragmatic Dysfunction

Department of Medicine, VA Long Beach Health Care System, Long Beach; Department of Medicine and Department of Orthopedic Surgery, Physiology and Biophysics, University of California, Irvine, California

Correspondence and requests for reprints should be addressed to Catherine S. H. Sassoon, M.D., Pulmonary and Critical Care Section, VA Long Beach Healthcare System (11/111P), 5901 East 7th Street, Long Beach, CA 90822. E-mail: csassoon{at}uci.edu

Controlled mechanical ventilation induced a profound diaphragm muscle dysfunction and atrophy. The effects of diaphragmatic contractions with assisted mechanical ventilation on diaphragmatic isometric, isotonic contractile properties, or the expression of muscle atrophy factor-box (MAF-box), the gene responsible for muscle atrophy, are unknown. We hypothesize that assisted mechanical ventilation will preserve diaphragmatic force and prevent overexpression of MAF-box. Studying sedated rabbits randomized equally into control animals, those with 3 days of assisted ventilation, and those with controlled ventilation, we assessed in vitro diaphragmatic isometric and isotonic contractile function. The concentrations of contractile proteins, myosin heavy chain isoform, and MAF-box mRNA were measured. Tetanic force decreased by 14% with assisted ventilation and 48% with controlled ventilation. Maximum shortening velocity tended to increase with controlled compared with assisted ventilation and control. Peak power output decreased 20% with assisted ventilation and 41% with controlled ventilation. Contractile proteins were unchanged with either modes of ventilation; myosin heavy chain 2X mRNA tended to increase and that of 2A to decrease with controlled ventilation. MAF-box gene was overexpressed with controlled ventilation. We conclude that preserving diaphragmatic contractions during mechanical ventilation attenuates the force loss induced by complete inactivity and maintains MAF-box gene expression in control.

Key Words: artificial respiration • diaphragm • isometric contractions • isotonic contractions • muscle atrophy

This article has been cited by other articles:

				G. C. Sieck and C. B. Mantilla Effect of Mechanical Ventilation on the Diaphragm N. Engl. J. Med., March 27, 2008; 358(13): 1392 - 1394. [Full Text] [PDF]

				K. Maes, D. Testelmans, S. Powers, M. Decramer, and G. Gayan-Ramirez Leupeptin Inhibits Ventilator-induced Diaphragm Dysfunction in Rats Am. J. Respir. Crit. Care Med., June 1, 2007; 175(11): 1134 - 1138. [Abstract] [Full Text] [PDF]

				E. Zhu, C. S. H. Sassoon, R. Nelson, H. T. Pham, L. Zhu, M. J. Baker, and V. J. Caiozzo Early effects of mechanical ventilation on isotonic contractile properties and MAF-box gene expression in the diaphragm J Appl Physiol, August 1, 2005; 99(2): 747 - 756. [Abstract] [Full Text] [PDF]

				D. Angus, A. Ishizaka, M. Matthay, F. Lemaire, W. MacNee, and E. Abraham Critical Care in AJRCCM 2004 Am. J. Respir. Crit. Care Med., March 15, 2005; 171(6): 537 - 544. [Full Text] [PDF]

				M. Decramer and G. Gayan-Ramirez Ventilator-induced Diaphragmatic Dysfunction: Toward a Better Treatment? Am. J. Respir. Crit. Care Med., December 1, 2004; 170(11): 1141 - 1142. [Full Text] [PDF]