The prilocaine is a very common local anesthetic that has the disadvantage of being metabolized to o-toluidine, a human carcinogen.

Hyperbaric 2% prilocaine (HP), recently developped, is increasingly used for spinal anesthesia in ambulatory surgery. But the formation of carcinogenic metabolites induced by the hyperbaric prilocaine is not yet known. The aim of this study is to investigate whether the intrathecal administration of 50 mg hyperbaric prilocaine induces also the formation of carcinogenic complexes such as urinary o-toluidine and hemoglobin adducts from o-toluidine in blood.

Inclusion Criteria:

• Age : > 18 years and < 80years
• American Society of Anesthesiology (ASA) score : I-II
• Height between 160cm and 180cm

Exclusion Criteria:

• Cardiac Disease (Aortic stenosis, heart failure...)
• coagulation disorder (International Normalized Ratio (INR) > 1.3; platelets <80 000/mm³)
• Allergic to local anesthetics
• Smoker

Patient scheduled for an ambulatory surgery