Fentanyl Versus Morphine in Spinal Anesthesia for Caesarian Section - Study on Perioperative Analgesia, Side Effects and Patient 's Satisfaction

The patients were randomly allocated into one of the two groups M (morphine) or F (fentanyl) with a sample size calculation at 1:1 ratio, using the envelope technique.

Group F (fentanyl) was administered hyperbaric bupivacaine 0.5% along with a standard dose of 25 mcg fentanyl, while group M (morphine) received hyperbaric bupivacaine 0.5% with a standard dose of 100 mcg morphine. The dose of hyperbaric bupivacaine 0.5% to be injected, was based on the patient's height and here were used a range of doses between 7.5 mg and 11 mg.

The study required two anesthetists. The first anesthetist was "in charge" and performed the spinal anesthesia and he was blind to the solution used. The second anesthetist randomly assigned the patient, drew up the intrathecal solution and provided the anesthetic mixture. By this method, the first anesthetist was totally blinded to the opioid used. All drugs were from the same manufacturer.

During the pre-anesthetic visit, the patient received information about the aims of the study, the method of anesthesia, and details about the pain management and about the pain assessment with the numeric pain scale (NPS). Patient's demographics data were obtained: height, term weight and age. Also, full medical past and drugs history, previous allergies and other important medical data were documented.

Pre-operatively a venous access was obtained with an 18 G. cannula and 500 ml of Ringer lactate solution was infused prior to anesthesia. Participants were fasting and received pantoprazol 40 mg and metoclopramide 10 mg as pre-anesthetic medication. The spinal anesthesia was performed in an aseptic technique with the patient in a sitting position, in the L3 - L4 interspace, using a midline approach, with a Whitacre 27 G. needle and the anesthetic mixture manually injected at a rate of 1 ml.15s-1, with a barbotage effect. A previous skin local anesthetic infiltration was performed with 2 ml of 1% lidocaine. After the block, the patient was placed in a supine position with a roll wedge placed under the right hip to displace the uterus to the left until fetal extraction. Volemic supply was assured with warm Ringer lactate (10-20 ml.kg-1hr-1). All patients than had anti-embolic socks on lower limbs.