* contraindication to prone position. * pregnancy. * weight \< 40 kg * height \< 140 cm or height \> 190 cm. * profuse bronchorrhea (at least 1 succion per hour during 3 hours). * other significant cause than ards to the respiratory failure. * decision to limit active therapies. * no arterial line in place. * obesity with weight / height ratio \> 1 kg / cm. * impossible to give neuromuscular blockers (e.g. drug unavailable owing to global pandemia). * severe chronic respiratory failure with oxygen at home. * other severe acute or chronic organ faillure (eg severe liver cirrhosis, severe chronic cardiac failure). * history of pneumonectomy or pulmonary lobectomy. * patient scheduled for extracorporeal membrane oxygenation. * known hypersensibility to curosurf. * contraindication to bronchial fibroscopy. * person under legal protection.

* contraindication to prone position. * pregnancy. * weight \< 40 kg * height \< 140 cm or height \> 190 cm. * profuse bronchorrhea (at least 1 succion per hour during 3 hours). * other significant cause than ards to the respiratory failure. * decision to limit active therapies. * no arterial line in place. * obesity with weight / height ratio \> 1 kg / cm. * impossible to give neuromuscular blockers (e.g. drug unavailable owing to global pandemia). * severe chronic respiratory failure with oxygen at home. * other severe acute or chronic organ faillure (eg severe liver cirrhosis, severe chronic cardiac failure). * history of pneumonectomy or pulmonary lobectomy. * patient scheduled for extracorporeal membrane oxygenation. * known hypersensibility to curosurf. * contraindication to bronchial fibroscopy. * person under legal protection.

- contraindication to prone position. - pregnancy. - weight < 40 kg - height < 140 cm or height > 190 cm. - profuse bronchorrhea (at least 1 succion per hour during 3 hours). - other significant cause than ards to the respiratory failure. - decision to limit active therapies. - no arterial line in place. - obesity with weight / height ratio > 1 kg / cm. - impossible to give neuromuscular blockers (e.g. drug unavailable owing to global pandemia). - severe chronic respiratory failure with oxygen at home. - other severe acute or chronic organ faillure (eg severe liver cirrhosis, severe chronic cardiac failure). - history of pneumonectomy or pulmonary lobectomy. - patient scheduled for extracorporeal membrane oxygenation. - known hypersensibility to curosurf. - contraindication to bronchial fibroscopy. - person under legal protection.

- contraindication to prone position. - pregnancy. - weight < 40 kg - height < 140 cm or height > 190 cm. - profuse bronchorrhea (at least 1 succion per hour during 3 hours). - other significant cause than ards to the respiratory failure. - decision to limit active therapies. - no arterial line in place. - obesity with weight / height ratio > 1 kg / cm. - impossible to give neuromuscular blockers (e.g. drug unavailable owing to global pandemia). - severe chronic respiratory failure with oxygen at home. - other severe acute or chronic organ faillure (eg severe liver cirrhosis, severe chronic cardiac failure). - history of pneumonectomy or pulmonary lobectomy. - patient scheduled for extracorporeal membrane oxygenation. - known hypersensibility to curosurf. - contraindication to bronchial fibroscopy. - person under legal protection.