Confusion and Hallucinations

Opioids are not the only cause of confusion, so ensure that other causes are sought and excluded, eg hypovolaemia, hypoxia, sepsis (including urinary tract infection), electrolyte disturbances, hypo- or hyperglycaemia, renal or hepatic dysfunction, cerebrovascular accident.  Confusion is common after a general anaesthetic or after a stay in intensive care.

Pain is also a cause of confusion so stopping analgesia may worsen, not improve, the situation.

Hallucinations are a feature of many drug withdrawal states such as alcohol Other Drugs of Abuse, opioids Clinical Opioid Withdrawal Scale (COWS) and benzodiazepines. 

If opioids are felt to be contributing to confusion, then the doses should be reduced and/or the dose interval increased.  If the patient is receiving epidural analgesia, the epidural infusate could be changed to one with less or no fentanyl Side Effects of Epidural Fentanyl.  If the patient’s analgesia is morphine-based, then consideration should be given to a switch to Oxycodone .