[Danger or security of spontaneous apnea in relation with previous ventilation (author's transl)].

Using a spectrometer for the study of exhaled gases and a monitor of transcutaneous oxygen pressure, our purpose has been to quantify our ideas about physiological apneas in the conscious voluntary adults. We compared the apneas, concerning the duration and the induced fall of peripheric oxygen pressure, after normoventilations in air and in oxygen, then after hyperventilations in air and in oxygen. These experiences confirm the tiny interest of previous normoventilation in oxygen compared with in air, the danger of hypoxemia by previous hyperventilation in air and the possibility of prolonged but safe apnea after hyperventilations in oxygen, that we can advocate in the induction of anaesthesia for some circumstances.