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Background and Aims Intrathecal morphine is commonly used for postoperative analgesia, with recommended doses typically ranging from 0.1 to 0.3mg. Despite its efficacy, adverse effects such as respiratory depression, hypotension, pruritus, and urinary retention can occur, particularly with higher doses. This report aims to discuss the clinical management and outcomes of a patient who inadvertently received a supratherapeutic dose of 2mg of intrathecal morphine.

Methods We present a clinical case involving a 72-year-old male, ASA II, scheduled for abdominoperineal resection, considered for a combined anaesthetic technique (neuraxial block and general anaesthesia). Multiple attempts at epidural blockade were unsuccessful, leading to perform a subarachnoid block with 0.2mg of morphine. However, a preparation error resulted in the administration of 2mg of intrathecal morphine.

Results The patient was promptly intubated and general anaesthesia was induced. He was admitted to the intensive care unit (ICU) for close monitoring, remaining mechanically ventilated for respiratory support. The patient was successfully extubated and discharged from the ICU on the third day without further complications.

Conclusions This case highlights the critical need for effective communication among team members and rigorous verification protocols when administering potent medications with narrow therapeutic range such as intrathecal morphine. It also underscores the importance of vigilant clinical monitoring and preparedness to manage potential adverse effects associated with medication errors. Ensuring stringent checks and fostering a culture of safety are paramount to prevent such incidents and ensure patient safety. Further education and training on medication administration protocols are recommended to enhance patient care outcomes.