A prospective observational study of intrathecal hyperbaric ropivacaine with nalbuphine or dexmedetomidine as adjuvants for cesarean section

Spinal anaesthesia is technique of choice for anaesthesia in patients undergoing caesarean section due to its rapid onset, decreased blood loss intense analgesia ,awake mother to permit bondage between mother and newborn,allowing early breastfeeding,early ambulation to the mother and minimizes the incidence of deep vein thrombosis while avoiding the complications of general anesthesia¹.The limitations of single shot spinal anaesthesia are it’s short duration of action and the need to supplement with parentral analgesics in the immediate post operative period .Several adjuvants have been added to prolong the duration of single shot spinal anaesthesia such as fentanyl, Dexmedetomidine, nalbuphine,clonidineetc...It has been added to local anesthetics to improve the quality of blockade and also to prolong the duration of post operative analgesia.

Ropivacaine has a lower central nervous and cardiac toxic potential than bupivacaine .Additionally ropivacaine is less potent and causes shorter duration of motor blockade than bupivacaine.Thus,hyperbaric ropivacaine is usually used for cesarean section ². Short duration of Ropivacaine cannot prevent visceral pain so analgesia supplementation in the intraoperative period or early analgesic intervention in the post operative period is often required.

Nalbuphine is highly lipid soluble opioid with agonist at ĸ receptors and weak agonist and antagonist at µ receptor. It is without significant effects on delta receptor. Nalbuphine has the potential to maintain or even enhance mu opioid based analgesia while simultaneously mitigating the common mu-opioid side effects. Nalbuphine elicits analgesia through a complex interaction of supraspinal ĸ3 and spinal ĸ1 mechanism and provides potent analgesia at spinal level.Nalbuphine acts primarily at the level of the first synapse in the nociceptive system in producing analgesia³. The respiratory depression is lesser than other opiods and has a safety profile with minimal effect on cardiovascular function and other side effects like nausea, vomiting ,constipation and psychotomimetic effects. It has minimal haemodynamic effects.

Dexmedetomidine is a highly selective alpha 2 adrenoceptoragonist,sedative,anxiolytic,analgesic,sympatholytic and antinociceptive characteristics.It mediates central alpha 2A and imidazoline type 1 receptors activation which results in decrease of norepinephrine release and leads to decrease in blood pressure and heart rate² .Both primary analgesic effects and potentiation of opioid induced analgesia result from activation of alpha 2 adrenergic receptors in dorsal horn of spinal cord and inhibition of substance P release and it’s hallmark is its analgesic efficacy without any respiratory depression .So far to my knowledge there is no study comparing hyperbaric ropivacaine with nalbuphine and Dexmedetomidine.