The purpose of this study is to assess if a dilution with 1.4% sodium bicarbonate of a 2% mepivacaine+epinephrine solution, can be effective in reducing the pain associated with local infiltration anesthesia, during ambulatory phlebectomy procedures.

The use of local anesthesia by infiltration (LIA), usually prepared with 1% lidocaine or mepivacaine 2%, in combination with epinephrine and diluted with saline solution, it's commonly performed in ambulatory phlebectomy procedures.

Although this kind of anesthesia is among the most effective and safe available, the infiltration of local anesthetic is accompanied by pain in the majority of patients. This can be particularly important in ambulatory phlebectomy procedures, where large areas need to be anesthetized.

Numerous methods have been proposed to alleviate the pain associated with LIA, such as reducing the rate of administration or warming the anesthetic solution.

Sodium bicarbonate added in small concentrations, can also be effective in reducing significantly the pain associated with LIA. A recent trial has confirmed the viability and effectiveness of a solution of lidocaine 1% diluted in sodium bicarbonate 1.4%, in varicose vein surgery.

The purpose of this study is to evaluate the effectiveness in alleviating the pain associated with LIA, of a solution of mepivacaine 2%+epinephrine diluted with sodium bicarbonate 1.4%, compared with an analogous solution diluted with normal saline.

Inclusion Criteria:

• Patients undergoing ambulatory phlebectomy

Exclusion Criteria:

• Allergy to amide anesthetics
• Sinoatrial node disease or any degree of atrio-ventricular block
• Acute diseases
• Chronic kidney or liver disease
• Treatment with drugs that alter pain sensitivity (e.g. analgesics)
• Treatment with monoamine oxidase inhibitors or tricyclic antidepressants
• Major psychiatric disorders according to DSM IV-TR diagnostic criteria
• Alcohol abuse actual or recent as described in DSM IV-TR