Abstract
Background: Diaphragm fatigue (DF) has been implicated in respiratory failure in diseases that
increase inspiratory resistance loading (IRL) and may complicate weaning of patients
from mechanical ventilation. Objective: The purpose of this study was to examine the effects of dobutamine administration
(10 μg/kg/min) on DF and to identify the mechanisms by which dobutamine augments diaphragm
shortening and diaphragm blood flow (DBF) during fatigue with a rat model. Methods: The study had an experimental design with 3 groups of Sprague-Dawley rats (n = 38)
with 4 experimental periods: period 1, control; period 2, application of IRL; period
3, treatment; and period 4, recovery. DF was produced via IRL. During period 3 treatment,
normal saline solution was infused in group I, dobutamine in group II, and dobutamine
plus butoxamine hydrochloride in group III. The percent change in fractional diaphragm
thickness (FDT) during inspiration reflected diaphragm shortening. DBF and aortic
blood flow were determined with fluorescent microspheres. Diaphragm vascular resistance
and systemic vascular resistance were calculated on the basis of Poiseuille's equation.
Results: Results indicated infusion of dobutamine increased FDT (P =.01) and DBF (P =.009) with respect to fatigue levels. The effects of dobutamine on FDT and DBF were
attenuated with infusion of butoxamine hydrochloride (a β-2 adrenoceptor antagonist)
with respect to fatigue. Conclusion: Administration of dobutamine at a rate similar to that used clinically increased
diaphragm muscle contractility (FDT) and DBF in diaphragms fatigued by IRL. The dobutamine
effect on FDT may be the result of restoration of the balance between diaphragm energy
consumption and energy delivery to the diaphragm by increasing DBF. Butoxamine hydrochloride
attenuated the dobutamine-induced increase in DBF, indicating dobutamine produced
vasodilatation via β-2 adrenoceptors. Thus, the administration of intravenous dobutamine
may be a useful adjunct in the treatment of DF. (Heart Lung® 2003;32:111-20.)
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References
- Force reserve of the diaphragm in patients with COPD.J Appl Physiol. 1983; 55: 8-15
- Clinical manifestations of inspiratory muscle fatigue.Am J Med. 1982; 73: 308-316
- Diaphragmatic pressure waveform can predict EMG signals of diaphragmatic fatigue.J Appl Physiol. 1987; 62: 1681-1689
- Workshop summary respiratory muscle fatigue.Am Rev Resp Dis. 1990; 142: 474-480
- Dobutamine increases diaphragmatic contractility in dogs.Can J Anaesth. 1992; 39: 375-380
- Contractility of fatigued diaphragm is improved by dobutamine.Can J Anaesth. 1993; 40: 453-458
- Isoproterenol and aminophylline improve contractility of fatigue canine diaphragm.Am Rev Respir Dis. 1984; 129: 118-124
- Effects and mechanism of action of terbutaline on diaphragmatic contractility and fatigue.J Appl Physiol. 1984; 56: 922-929
- Blood flows within and among rat muscles as a function of time during high speed treadmill exercise.J Physiol. 1983; 344: 189-208
- Exercise blood flow patterns within and among rat muscles after training.Am J Physiol. 1984; 246: H59-H68
- Correspondence of pulmonary and leg VO2 at submaximal work rates: implications for estimation of work efficiency.J Appl Physiol. 1992; 72: 805-810
- Effects of β1-and β2-adrenoceptor stimulation on hemodynamics in the anesthetized rat.J Cardiovasc Pharmacol. 1990; 15: 720-728
- Response of nitric oxide in vasodilator response induced by salbutamol in rat diaphragmatic microcirculation.Am J Physiol. 1997; 272: H2173-H2179
- Different β-adrenergic receptor density in different rat skeletal muscle fibre types.Pharmacol Toxicol. 1995; 76: 380-385
- β-adrenergic receptor distribution among muscle fiber types and resistance arterioles of white, red, and intermediate skeletal muscle.Circ Res. 1989; 64: 1096-1105
Article info
Footnotes
*Financial support provided by NIH-NRSA 5 F31 NRO7341-02.
**Work performed at the University of Kansas Medical Center.
*Reprint requests: Nan Smith-Blair, PhD, RN, Assistant Professor, University of Arkansas, Eleanor Mann School of Nursing, 217 Ozark Hall, Fayetteville, AR 72701.
**0147-9563/2003/$30.00 + 0
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© 2003 Published by Elsevier Inc.
