[The clinical use of spinal opioids, part 2]

The most significant non-systemic side effects of spinal opioids are pruritus, urinary retention and delayed respiratory depression. Pruritus can occur after any opioid, but its incidence may differ with the affinity of the particular opioid to the opioid receptor. Spinal opioid receptors seem to influence urinary retention due to urodynamic effects. Urinary retention can be antagonized by naloxone; however, large doses will also antagonize the analgesic effects. Delayed respiratory depression after spinal opioids is a very rare, but significant complication. In general, respiratory depression after spinal lipophilic opioids will occur earlier than morphine, however the incidence is probably similar. There is some evidence to suggest that the risk of respiratory depression is similar regardless of the route of administration (intramuscular, intravenous, spinal, PCA). Sound knowledge among physicians and nurses, adequate treatment plans, and individual patient selection are essential to avoid significant complications of spinal opioids. If these requirements are fulfilled, most patients can be safely treated with spinal opioids even outside the intensive care unit.