Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease which involves respiratory muscles and can lead at short term to respiratory failure. The occurrence of respiratory failure is associated with morbidity and an increased mortality. To date, respiratory muscle weakness is predicted from the reduction of vital capacity, maximal inspiratory force, nocturnal symptoms and hypercapnia. Even taken together, the predictive value of these indices is low. The investigators hypothesize that an endurance test of diaphragmatic work would be more sensitive to respiratory muscle involvement than maximal respiratory force. Consequently, the investigators assessed diaphragmatic performance through an isocapnic hyperventilation test (IHT) in patients at the onset of ALS and, then regularly up to the occurrence of respiratory failure. The investigators make the hypothesis that IHT will be altered earlier than maximal inspiratory force
Study Type
OBSERVATIONAL
Enrollment
136
This consists of hyperventilation in a flask while maintaining the constant level of Carbon Dioxide (CO2). The patient will realize hyperventilation to increasing levels of Maximum Minute Ventilation (MMV), corresponding to increasing levels of respiratory rate, until exhaustion
CHU de SAINT-ETIENNE
Saint-Etienne, France
Endurance time
Difference in endurance time during the IHT between healthy controls and ALS patients when diagnosis is established
Time frame: Day 1
Reference values of the diaphragmatic endurance test
Reference values of the diaphragmatic endurance test in healthy controls according to age, by 10 years range.
Time frame: Day 1
Reference values of phrenic nerve activity
Reference values of phrenic nerve activity in healthy controls according to age. It is measured with diaphragmatic Electromyogram by cervical electrical stimulation.
Time frame: Day 1
Slope of endurance time decrease
Slope of endurance time decrease with time in ALS patients measured during IHT
Time frame: At Day 1 and every 3 months of follow-up (3 years)
Amplitude of phrenic nerve
It is the relationship between phrenic nerve activity and diaphragmatic endurance in ALS patients
Time frame: At Day 1 and every 3 months of follow-up (3 years)
Latency of phrenic nerve
It is the relationship between phrenic nerve activity and diaphragmatic endurance in ALS patients
Time frame: At Day 1 and every 3 months of follow-up (3 years)
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