Intrathecal opioids for the management of post-operative pain

Abstract

Intrathecal opioids are highly effective in the management of post-operative pain. The technique is simple with a very low risk of technical failure or complications, and it does not require additional training or expensive equipment such as ultrasound machines and, therefore, is widely practised around the world. The high-quality pain relief is not associated with sensory, motor or autonomic deficits. This study focuses on intrathecal morphine (ITM) which is the only US Food and Drug Administration-approved opioid for intrathecal administration and remains the most commonly used as well as extensively studied. The use of ITM is associated with prolonged analgesia lasting 20-48 h after a variety of surgical procedures. ITM has a well-established role in thoracic, abdominal, spinal, urological and orthopaedic surgeries. It is considered the 'gold standard' analgesia technique for caesarean delivery which is generally performed under spinal anaesthesia. As the role of epidural technique in post-operative pain management continues to decrease, ITM has emerged as the neuraxial technique of choice for pain management after a major surgery as a component of multimodal analgesia in Enhanced Recovery After Surgery (ERAS) protocols. ITM is recommended by many scientific groups and societies such as ERAS, PROSPECT, the National Institute for Health and Care Excellence and the Society of Obstetric Anesthesiology and Perinatology. The doses of ITM have decreased successively; today they are a fraction of those used in the early 1980s. With these dose reductions, the risks have decreased; current evidence shows that the risk of the much-feared respiratory depression with low-dose ITM (up to 150 mcg) is no greater than that with systemic opioids used in routine clinical practice. Patients receiving low-dose ITM can be nursed in regular surgical wards. The monitoring recommendations from societies such as the European Society of Regional Anaesthesia and Pain Therapy (ESRA), the American Society of Regional Anesthesia and Pain Medicine and the American Society of Anesthesiologists need to be updated so that the requirements for extended or continuous monitoring at postoperative care units (PACUs), step-down units, high-dependency units, and intensive care units can be eliminated, thereby reducing additional costs and inconvenience and making this simple, versatile and highly effective analgesia technique available to a wider patient population in resource-limited settings.

Keywords: ERAS; analgesia; intrathecal; opioids; postoperative pain; respiratory depression.