Exploration du diaphragme en réanimation

Abstract

The diaphragm is the main agonist of normal inspiration. To ensure an alveolar ventilation adequately balancing the production of carbon dioxyde, the diaphragm must be able to overcome the impedance of the respiratory system and must have an adequate endurance. If this is not the case, hypercapnic respiratory failure can occur. Studying diaphragm function in critically ill patients implies a careful clinical examination of the thoraco-abdominal movements during tidal breathing. Spirometry, inspiratory pressures (static and dynamic – “sniff test”) and blood gases must be measured. Phrenic nerve stimulation quantifies diaphragmatic dysfunction and is helpful to understand its mechanisms. Transcranial magnetic stimulation can ascertain the central origin of such abnormality. A careful description of diaphragm function can be useful in diseases impairing the neuromuscular function of the respiratory system, to investigate the mechanisms of difficult weaning from the ventilator or to assess the respiratory repercussions of ICU acquired polyneuropathies. Modern techniques for phrenic stimulation, both non-invasive and easy to apply, should in the future promote diaphragm studies in the clinical setting, in these indications.