Prospective observational study in 4 intensive care units in one general hospital and one university hospital.
Once Nicardipine or Urapidil infusion is started, data collection of respiratory related information such as type of ventilation, arterial partial pressure of oxygen, blood pressure, cardiac frequency.
Statistical analysis for two qualitative variables: Group (Nicardipine or Urapidil) and occurrence or worsening of hypoxemia. Secondary outcoumes analysed such as maximal drop of blood pressure, evolution of the PaO2/FiO2 ratio, length of hospital stay, duration of mechanical ventilation in the ventilated patients.
Analysis for different subgroups : Patients with known atelectasis, postoperative of cardiac surgery, neuro-intensive care.
