[Non-invasive modalities of mechanical ventilation].

When first developed in the fifties and sixties during the major polio epidemics, artificial ventilation was a major advance in medical care. The negative pressure perithoracic "iron lungs" had however many disadvantages and were widely replaced by positive pressure ventilation with intubation. This invasive technique allows normalization of gas exchange but has the disadvantage of requiring artificial sedation of the respiratory muscles in many cases in addition to the risk of secondary complications. Several authors have recently shown that in many cases, intubation may not be necessary since nasal mask positive pressure ventilation can provide satisfactory results in selected patients. Basically, indications involve patients suffering from acute decompensation of chronic obstructive respiratory failure. Prospective studies have demonstrated beneficial effects in terms of dyspnea and patient discomfort. A clear improvement over the classical medical care (oxygen, bronchodilators, antibiotics) has been observed. Other indications include certain cases of acute neuromuscular diseases, cardiogenic pulmonary edema or severe acute pneumonia. The technique can rarely be used 24 hours a day, at least during the first days of therapy and cannot provide total respiratory support in case of acute respiratory failure. Other inconveniences include leaks around the mask and the need for careful surveillance by the health care workers. Today, there are several arguments based on prospective clinical studies showing that intubation may be avoided in certain patients by using non-invasive positive pressure ventilation with a nasal mask. Careful patient selection is however essential in addition to knowledge of the limitations of the technique.