In the context of postoperative hypertension in the intensive care units, or after resusitation of hypertensive patients, intravenous antihypertensive drugs are often used. Among those drugs, Nicardipine is an effective drug, but with side effects such as inhibition of pulmonary vasoconstriction. Only preclinical studies have investigated the pathophysiology of this mechanism, and no clinical study have proven its clinical relevance.

The aim of this study is to establish the incidence of Nicardipine induced hypoxemia and to compare it to another antihypertensive agent, Urapidil.

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.

Inclusion Criteria:

• Major patient
• With acute arterial systolic hypertension over 140mmHg
• Requiring intravenous administration of one of the two following drugs : Urapidil or Nicardipine

Exclusion Criteria:

• Patient ventilated Under Nitrogen Monoxyde
• Contraindication to Nicardipine or Urapidil
• Refusal of the patient or his relatives
• Patient treated for pulmonary hypertension

All hypertensive patients in the intensive care unit