Efficacy Of Intrathecal Ropivacaine And Morphine Versus Intrathecal Morphine Alone As Preventive Analgesia In Patients Undergoing Posterior Lumbar Spine Surgery: A Prospective Randomized Double Blind Comparative Study

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage (definition by IASP). There are four major types of pain, nociceptive pain (due to tissue injury), inflammatory pain, neuropathic pain (due to nerve irritation) functional pain (due to no obvious origin). Pain has seven dimensions or core aspects: physical, sensory, behavioral, socio-cultural, cognitive, affective, and spiritual. Lumbar spine surgery is routinely performed in patients for various indications to mitigate back pain, lessen neurological symptoms, and improve mobility. The major indications broadly include trauma, infection, malignancy, congenital, and degenerative disease. It is known to be a major surgical procedure associated with severe postoperative pain requiring comprehensive management. Poorly managed postoperative analgesia culminates into delayed mobilization, prolonged hospital stay, morbidity and delayed rehabilitation. There is growing evidence that acute post-operative pain also influences the development of chronic pain through central or peripheral sensitization of receptors. Recently, enhanced recovery programs necessitate satisfactory analgesia and a number of modalities ranging from nonsteroidal anti-inflammatory drugs, opioids, and local anaesthetics have been used. Multimodal analgesia is an invaluable tool for escalating recovery. One of the methods for post-operative analgesia that has gained popularity in recent years is the intrathecal opioid administration in which opioid is directly injected into cerebrospinal fluid and acts directly on the opioid receptors present in the substantia gelatinosa and inhibit presynaptic and postsynaptic nociceptive transmission without sympathetic effects. Morphine, the prototypical opioid, has been the most widely accepted for intrathecal administration. Intrathecal morphine has a good role in post-operative pain management as it produces segmental analgesia, which causes localized nociception without sensory, motor, autonomic, or systemic side effects. However, it is associated with various side effects in postoperative period such as pruritus, somnolence, respiratory depression, vomiting and urinary retention. This makes it imperative that the dose of opioids needs to be attenuated to avoid unwanted side effects that impede recovery. Preemptive analgesia entails adopting techniques prior to pain registration in the central neurons and further amplification. The onset of action of morphine starts from 30-60 minutes and it can last for about 4-24 Hours. Local anaesthetic drugs such as ropivacaine have been used for spinal anaesthesia in spine surgeries and have immediate onset of action. Anesthesiologists have been combining local anesthetic (bupivacaine) with morphine so as to reduce its dose. Intrathecal morphine in combination with local anesthetic is an emerging technique wherein the onset of analgesia is immediate and dose of morphine may be further reduced, providing preventive analgesia. Hence we designed this study to compare the analgesic efficacy of 0.2% ropivacaine plus 200 mcg of intrathecal morphine with 200 mcg of intrathecal morphine in posterior lumbar spine surgery.

**RESEARCH QUESTION OF THE STUDY -**To determine whether adding ropivacaine to low dose intrathecal morphine provides superior analgesia as compared to intrathecal morphine alone in patients undergoing lumbar spine surgeries?