Influence of addition of morphine,fentanyl or nalbuphine to bupivacaine spinal anaesthesia for cesarean delivery

The aim of the present study was to evaluate the influence of addition of morphine, nalbuphine or fentanyl to bupivacaine spinalanaesthesia for cesarean delivery.The present study was carried out on one hundred healthy ASA-... physical status I mothers at full term who were scheduled for elective.Spinal anaesthesia is commonly used for cesarean delivery, and it has become a popular practice to add opioids to local anaesthetics to enhance and prolong intraoperative and postoperative analgesia.Lipid solubility determines the onset and duration of action of the used opioid. Lipophilic drugs such as nalbuphine and fentanyl rapidly penetrate into lipid-rich spinal tissue to activate the opiate receptors resulting in rapid onset of action. Furthermore, increased lipid solubility facilitates vascular uptake with subsequent decline in the concentration of the opioid in the CSF resulting in short duration of action. In contrast,hyDROPhilic drugs such as morphine has difficulty in traversing neural and vascular membranes and tends to remain in the CSF resulting in delayed onset with long duration .