Clonidine With Morphine in Patient Controlled Analgesia Pump in Vaso-Occlusive Crisis in Sickle Cell Disease Patient

Vaso-occlusive crisis are highly painful in Sickle-cell patients. Morphine is the treatment of choice for this pain. Various adjuncts have been studied for the treatment of vaso-occlusive crisis. The investigators aimed to study the effect of clonidine associated with morphine in PCIA (patient controlled intravenous analgesia pumps) regimen. The investigators will compare it to the morphine alone in PCIA for the treatment of vaso-occlusive pain. The investigators will measure the morphine consumption of all patient, the impact on the apparition of the morphine secondary effect and on inflammation biomarkers and the biopsychosocial respond. Each patient will be hospitalized and follow by haematologist from the hospital, pain doctors and nurses. It will be a double blind randomised, prospective study. The randomisation will be done by the pharmacy.