Intrathecal opioids in the management of acute postoperative pain

In 1968, Melzack and Wall put forward their ‘gate control theory’ proposing that the spinal cord was a potential target site for modulation of pain signals. This changed our concepts about nociceptive transmission and laid the foundation for further research into dorsal horn opioid pharmacology. This led to the discovery of opioid receptors by Pert and Snyder in 1973 and the subsequent identification of dorsal horn opioid receptors by radioligand techniques in 1977. Yaksh went on to demonstrate that opioids modulate nociceptive stimuli via a direct action on the spinal cord in 1976. Wang was the first to describe the intrathecal administration of morphine in a group of eight patients with genitourinary malignancies in 1979. Since that time, the use of intrathecal opioids has become a widely accepted technique for providing effective postoperative pain relief. The changing health economy has driven the need for greater patient throughput, rapid turnover and shorter hospital stays whilst retaining high quality medical care. The combination of intrathecal analgesia with minimally invasive surgery has led to the development of accelerated surgical care pathways. This review will focus on the use of intrathecal opioids in the acute postoperative pain setting.