Function and Bulk of Respiratory and Limb Muscles in Patients with Cystic Fibrosis

Abstract

Inspiratory muscle weakness due to lung hyperinflation and muscle wasting may occur in cystic fibrosis. We therefore measured diaphragm function and bulk in 18 stable patients with cystic fibrosis and 15 matched control subjects; the abdominal and quadriceps muscles were studied for comparison. We assessed diaphragm mass, abdominal muscle thickness, twitch transdiaphragmatic and gastric pressures, quadriceps cross-section and isokinetic strength, and lean body mass. Lean body mass, quadriceps strength, and quadriceps cross-section were lower in patients with cystic fibrosis. Twitch transdiaphragmatic pressure was 23% lower and twitch gastric pressure was 22% greater in patients with cystic fibrosis than in control subjects, but diaphragm mass and abdominal muscle thickness were similar in the two groups. For any given lean body mass and quadriceps cross-section, patients with cystic fibrosis had greater diaphragm mass and abdominal muscle thickness. Diaphragm mass had greater intersubject variability in patients with cystic fibrosis than in control subjects. We conclude that diaphragm strength is decreased but abdominal muscle strength is increased in patients with cystic fibrosis. Diaphragm and abdominal muscle bulk are not affected by the general muscle wasting, which suggests that there may be a training effect of cystic fibrosis on respiratory muscles. However, the variability of diaphragm mass indicates that this beneficial response does not occur in all patients with cystic fibrosis.

Sex differences in thoracic adaptation to pulmonary hyperinflation in cystic fibrosis

“…The pressure developed by the inspiratory muscles is also determined by their mass and by their mechanical advantage in converting the tension developed into effective inspiratory pressure. The mass of the diaphragm was reported to be well preserved in CF patients in spite of malnutrition, a finding which was interpreted as reflecting a training response to the increased respiratory load [2]. As the present results suggest, a greater fraction of the inspiratory load was taken up by the inspiratory ribcage muscles in the CF group.…”

“…KEYWORDS: Chest wall, chest radiography, diaphragm, sex, respiratory muscles P ulmonary hyperinflation, as occurs in cystic fibrosis (CF) patients, may impair thoraco-abdominal mechanics and the function of the inspiratory muscles [1,2], factors that may contribute to dyspnoea and poor exercise tolerance [3]. A shortening of the inspiratory muscles, particularly the diaphragm [4][5][6][7], and a change in its geometry with pulmonary hyperinflation [6][7][8], are factors known to reduce the pressure-generating capacity of the inspiratory muscles.…”

“…A shortening of the inspiratory muscles, particularly the diaphragm [4][5][6][7], and a change in its geometry with pulmonary hyperinflation [6][7][8], are factors known to reduce the pressure-generating capacity of the inspiratory muscles. However, the effect of pulmonary hyperinflation on maximum inspiratory pressure in CF patients is controversial, some studies reporting a decrease [1,2,9,10], others no change [11], and yet others an improvement in maximum inspiratory pressure in spite of pulmonary hyperinflation [12]. It is very difficult to reconcile these different results.…”

Urinary incontinence in adolescent females with cystic fibrosis in Poland

“…Based on some studies it has been suggested that peripheral muscle force might be negatively related to the inflammatory state in patients with COPD [12]. Pinet et al demonstrated that inflammatory markers would not adversely affect muscle strength in patients with CF, however, this study may not reflect the findings in the pulmonary exacerbation; that study was conducted on clinically stable patients [13]. Constipation is a known risk factor for failure of the continence mechanism [14][15][16].…”

Skeletal muscle weakness, exercise tolerance and physical activity in adults with cystic fibrosis

“…It has been suggested that patients with CF may suffer from skeletal muscle weakness. However, these reports are from relatively small cohorts [8] or patients with severe CF [9,10]. A recent larger study including 33 patients with milder disease suggested that peripheral muscle force was not significantly reduced [11].…”