Sedation With Dexmedetomidine Versus Remifentanil in Urogynecological Surgery Under Spinal Anaesthesia

Sedation With Dexmedetomidine Versus Remifentanil in Urogynecological Surgery Under Spinal Anaesthesia : Impact on Block Characteristics, on Acute and Chronic Postoperative Pain

Neuraxial blocks are usually used as an anaesthetic method for urogynecological surgeries. In most patients under regional anaesthesia, premedication is given for reducing anxiety. Purpose of this prospective double blind randomised clinical trial is the investigation of the effect of perioperative intravenous infusion of dexmedetomidine vs remifentanil for sedation in patients under spinal anaesthesia for urogynecological procedures.

The day before surgery the procedure will be explained to the patient and the written consent will be obtained. In the operating room, intraoperative monitoring will include ECG, noninvasive blood pressure, oxygen saturation by pulse oximetry (SpO2) and heart rate (HR). A peripheral intravenous catheter wil be placed for fluid replacement ( Ringer's Lactate solution 6 - 8ml/ kg/hr) and administration of drugs.

Women will be randomly assigned into one of two groups:

Group A: Women will receive dexmedetomidine continuously infused at a dose of 0,6 mcg/kg for 10 minutes (concentration of the solution 6mcg/ml) before spinal anaesthesia. Infusion will be stopped in order to proceed with regional anesthesia.

Group B: Women will receive remifentanil continuously infused at a dose of 1mcg/kg for 10 minutes (concentration of the solution 1mcg/ml) before spinal anaesthesia. Infusion will be stopped in order to proceed with regional anesthesia.

The insertion of a 27 Gauge (27G) spinal needle is performed at L3-L4 or L4-L5 interspace, in the lateral position. All patients will receive 2,7 ml ropivacaine 0,75% and 15 mcg fentanyl intrathecally and assessment of sensory and motor block will be assessed every 2 min. The moment that sensory block is in the highest dermatome and motor block is complete (Bromage grade 3) is Time to max effect (Tmax). In group A an infusion of dexmedetomidine (6mcg/ml) at a dose of 0,6mcg/kg/hr will be administered and in group B an infusion of remifentanil (1mcg/ml) at a dose of 0,03 mcg/kg/min.At the end of the surgery patients will be transferred in Post Anaesthetic Care Unit (PACU) and a patient control analgesia (PCA) pump will be provided to the patient, administering 1 mg of morphine in every attempt, with a lock out interval of 10 minutes.There will be no continuous infusion. All patients will receive a standardized multimodal approach, including diclofenac 50 mg t.i.d, paracetamol 1gr as rescue analgesia (max 4 gr per day) and PCA with morphine.

Inclusion Criteria:

• Physical status according to American Society of Anesthesiologists (ASA) I-II
• Patients scheduled for transvaginal urogynecological or gynecological surgery

Exclusion Criteria:

• Patient refusal
• Contraindication of spinal anaesthesia (Coagulopathy, Local infection at the site of injection, Local anaesthetic allergy, Hypovolaemia)
• BMI > 30 kg/m2
• Personal history of cardiovascular disease
• Arrythmias
• Conduction disorders
• Severe kidney or liver dysfunction
• Insulin-dependent diabetes mellitus
• Central nervous system disorders
• Psychiatric and mental status disorders
• Chronic Excessive Alcohol Consumption
• Chronic Use of Opioid Analgesics
• Chronic Use of corticosteroids
• Chronic Use of clonidine (or other a2 adrenergic agonist)
• Use of drugs acting on central nervous system or analgetics the last two weeks
• Communication problems due to language barriers or unable to understand the pain scale