Contrôle de la ventilation : physiologie et exploration en réanimation

The respiratory command emerges from neuronal networks located in the brainstem. It is then dispatched toward the respiratory muscles. The dilators of the upper airway contract first and the inspiratory muscles of the chest, including the diaphragm, some milliseconds later. Afferent inputs arising from chemo- and mechanoreceptors, related to the physical status of the respiratory system and to the activation of the respiratory muscles, modulate permanently the respiratory command to adapt ventilation to the needs of the body. Many diseases that lead patients to the ICU can modify, directly or indirectly, the respiratory command. Many treatments used in ICU can also alter this command. For example, mechanical ventilation decreases it. Should an inexplicable respiratory trouble or a difficult weaning occur, the control of breathing may be explored. This may help the diagnosis and the treatment. The exploration relies on assessments of spontaneaous ventilation and on its response to stimulations.