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Effect of N-acetylcysteine on human diaphragm strength and fatigability
- Source :
- American journal of respiratory and critical care medicine. 156(5)
- Publication Year :
- 1997
-
Abstract
- Free radical injury is believed to be important in diaphragm dysfunction. N-Acetylcysteine (NAC) is a potent free radical scavenger shown in animal models to attenuate diaphragm fatigue; however, its effects on human diaphragm function are unknown. We assessed diaphragm function by electrophrenic twitch stimulation (PdiT) and twitch occlusion (to yield Pdimax) in four healthy subjects 35 +/- 3 yr of age (mean +/- SD). We intravenously administered NAC (150 mg/kg in 250 ml D5W) or placebo (CON) (250 ml D5W) in a randomized manner after subjects were premedicated with antihistamines. There were no significant side effects with the infusion. After infusion, we measured baseline Pdimax and PdiT at FRC. Diaphragm fatigue was then induced by subjects breathing through an inspiratory resistive load. Pdimax and PdiT were then measured at 15 to 30 min and 1, 2, 3, 4, and 20-25 h after fatigue. Times to fatigue were 13 +/- 4 min (CON) and 21 +/- 6 min (NAC) (p = 0.04). At 15 min after fatigue, PdiT was reduced to 40% (CON) compared with 30% (NAC) initial PdiT value (p = 0.05). Other twitch characteristics (maximal rate of relaxation and maximal contraction rate) were reduced to a greater degree after placebo compared with NAC. There were no significant differences in the rate of recovery between CON and NAC. Pdimax at 30 min after fatigue was significantly greater with NAC; however, at 1 h after fatigue, Pdimax for CON and NAC were not different, suggesting similar rates of recovery in high-frequency fatigue. These data suggest that NAC may attenuate low-frequency human diaphragm fatigue.
- Subjects :
- Pulmonary and Respiratory Medicine
Adult
medicine.medical_specialty
Muscle Relaxation
Diaphragm
Action Potentials
Stimulation
Critical Care and Intensive Care Medicine
Placebo
Acetylcysteine
Diaphragm function
Double-Blind Method
medicine
Humans
business.industry
Healthy subjects
Free Radical Scavengers
Free radical scavenger
Electric Stimulation
Diaphragm (structural system)
Surgery
Anesthesia
Muscle Fatigue
Breathing
business
medicine.drug
Muscle Contraction
Subjects
Details
- ISSN :
- 1073449X
- Volume :
- 156
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- American journal of respiratory and critical care medicine
- Accession number :
- edsair.doi.dedup.....b10be15957f1f7e3d6b906646a668ae0