title: The consequences of diaphragmatic muscle fatigue in the newborn infant.
abstract: We have previously demonstrated that diaphragmatic muscle fatigue can be diagnosed in infants from spectral frequency analysis of the surface diaphragmatic electromyogram. This requires a digital computer, but the analysis takes several days. Spectral frequency changes, however, can be accurately reflected by band pass filtering and expressing the ratio of high-frequency power to low-frequency power. A fall in this ratio of greater than 20% indicates muscle fatigue. Using a simple analog device to obtain this ratio permits the results to be immediately available; we have used this method to study weaning from mechanical ventilators in ten infants. With a successful weaning step there is no significant change in the ratio, whereas an unsuccessful weaning step invariably leads to a decrease in the ratio of greater than 20%, which precedes CO2 retention and clinical deterioration. These data indicate that diaphragmatic muscle fatigue plays an important role in the infant's response to lung disease. Monitoring of the high/low frequency ratio may be helpful in weaning infants from assisted ventilation.
mesh_terms: D003202:Computers, Analog; D003964:Diaphragm / Q000503:physiopathology*; D004562:Electrocardiography; D004576:Electromyography / Q000295:instrumentation; D005221:Fatigue / Q000503:physiopathology*; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000503:physiopathology*; D011175:Positive-Pressure Respiration; D012131:Respiratory Insufficiency / Q000503:physiopathology* / Q000628:therapy; D014939:Work of Breathing