| Abstract: |
The respiratory muscles are essential to alveolar ventilation. In COPD patients, these muscles work against increased mechanical loads due to airflow limitation and geometrical changes of the thorax due to the effect of pulmonary hyperinflation. These structural impairments are translated from the functional point of view to a loss of strength (capacity to generate tension) and an increase of susceptibility to failure in the face of a particular load (early onset of fatigue). The aim of this work was to study diaphragmatic muscle fatigue in COPD patients and its possible relations to acidosis, hypercapnemia, hypoxemia, pulmonary hyperinflation, malnutrition and/or electrolytes disturbance.This study was conducted on (60) patients with COPD and (20) healthy subjects as a controls. Each of them was submitted to detailed clinical history and examination, routine investigations including(CBC, liver & kidney functions and ECG), pulmonary ventilatory function tests, arterial blood gases measurement, assessment of nutritional status, assessment of (pdi) and (pdi max) to evaluate diaphragmatic function. Radiological evaluation of the diaphragm by plain chest x-ray film (PA & lateral views) and ultrasonography was conducted to measure the thickness of the diaphragm and its excursion. High- resolution CT was performed to detect the degree of pulmonary hyperinflation.Results of this study showed that, the pulmonary ventilatory functions of all patients showed an irreversible obstructive pulmonary dysfunction pattern. FVC%, FEV1%, FEV1/FVC%, FEF25-75%, were significantly lowered and irreversible after bronchodilator in COPD patients than in control group.Hypoxemia and hypercapnemia were demonstrated in COPD patients. Hypoxemia was mainly attributed to V/Q mismatch, while hypercapnemia was presumed to be caused by respiratory muscle impairment and alveolar hypoventilation.Malnutrition was detected in COPD patients. Assessment of the nutritional status involved measurements of body weight, height, body mass index, arm circumference, triceps skin fold thickness and midarm muscle circumference was performed. All these measurements were significantly lowered in COPD patients than in control group.
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