Comparison of Standard and Minidose Spinal Anesthesia for Cesarean Section Operation Using Marcaine Spinal 0.5% Heavy

Phase IV, Randomized, Parallel Designed, Single Blinded Study, Comparing the Standard and Minidose Spinal Anesthesia Using Marcaine Spinal 0.5% Heavy With Addition of Fentanyl During Cesarean Section

The objectives of this study is to test a combination of low dose local anesthetic Bupivacaine diluted in patient's CSF with lipophilic opiate Fentanyl for optimal spinal anesthesia during Cesarean Section. The dilution of Bupivacaine with CSF in our study would result in effective spinal anesthesia with relatively limited motor block, quick recovery of motor function and relatively long lasting analgesia. We expect lower incidence of side effects with this combination than with convenient dose of Bupivacaine.

Spinal anesthesia is the most frequent type of anesthesia used for Cesarian Section. However, despite decades of safe utilization there is still controversy about the best combination of local anesthetics and additives needed to obtain the optimal result. The objectives of this study is to test a combination of low dose local anesthetic Bupivacaine diluted in patient's CSF with lipophilic opiate Fentanyl for compliance with the criteria of optimal spinal anesthesia. Bupivacaine is the most frequently used local anesthetic in the last twenty years . It characterized by fast onset, high potency and long action . Albeit this is intrinsic characteristic of specific local anesthetic, its manifestation can be affected by concentration. It has been shown that dilution of local anesthetic with CSF can result in sensory block with less profound motor block.

Thus dilution of Bupivacaine with CSF in our study would serve double function: it would speed the recovery from the spinal anesthesia and minimize the expression of the motor block.Addition of opiates to local anesthetics has been widely used . It has been shown that this addition improves quality of spinal anesthesia and prolongs analgesia without significant prolongation of recovery from motor block.

In summary, we would use well known safe local anesthetic Bupivacaine in low dose and low concentration (after dilution with patient's CSF) in conjunction with highly lipophilic opiate Fentanyl. We suppose it will result in effective spinal anesthesia with relatively limited motor block, quick recovery of motor function and relatively long lasting analgesia. We expect lower incidence of side effect with this combination than with convenient dose of Bupivacaine.

Good pain relief and swift restoration of ability to ambulate will be important for prevention of postoperative complications, will diminish the need for systemic analgetic drugs that can affect nursing and will increase patients' satisfaction.

Inclusion Criteria:

• Women over 38 weeks of pregnancy, who read and write Hebrew
• ASA class I and II
• Age between 18 and 40 years
• Weight 50-100 kg
• Elective Cesarean Section for singlet pregnancy

Exclusion Criteria:

• Previous history of two or more Cesarean Sections
• Contraindications for regional anesthesia
• Active pain before surgery
• Non singlet pregnancy