This is a 75-year-old woman with a history of type II DM under insulin treatment with chronic complications such as polyneuropathy, HTN under treatment and obese, who is scheduled for PTR (total knee replacement) surgery. The anaesthetic technique was a combined epidural/intradural procedure at L3-L4 level, 3 ml of bupivacaine 0.5% without vasoconstrictor was administered through the intradural needle and an epidural catheter was left in place for postoperative analgesia. The postoperative period was uneventful and she went upstairs with a PCAE (epidural PCA) loaded with bupivacaine 0.125 and fentanyl 4 micrograms per ml, with a schedule of 3 ml.h-1, 3 ml boluses every 30 minutes. At approximately 4 a.m. the PCA was changed, causing the error and administering via epidural a PCA with medication and programming for i.v. (in 100 ml, 50 mg of fentanyl every 30 minutes). (in 100 ml, 50 mg of morphine plus 10 g of metamizole).
At the time of the daily visit to the PACU, the nurse of the PACU detects the error. The patient is conscious and oriented with excellent analgesia, with no evidence of respiratory depression, neurological alterations or other side effects. The amount of drug administered was 4 mg morphine and 160 mg metamizole. The PCA and catheter were removed and the patient was admitted to the Resuscitation Unit for control and follow-up, where she did not present any side effects and remained stable at all times. 24 hours later, she was discharged to the ward and 2 weeks later she was discharged home, after a review by the anaesthesiologist. Periodic follow-up was carried out for up to 18 months without any incidence.