A 64-yr-old man (163 cm, 56 kg) was scheduled to undergo left lower lobectomy for lung cancer under total i.v. anaesthesia with a prefilled propofol syringe (Diprivan 1% infusion kit, Astra Zeneca, Sweden), and epidural block. The prefilled propofol syringe was assembled and set on an infusion pump (Anaesthesia Pump 3500, Graseby Medical, Hertfordshire, UK) by an attending nurse before induction. After epidural catheter insertion via the T4/5 intravertebral space, the prefilled propofol syringe was connected to the patient via a three-way stopcock. The stopcock was opened to the patient, but the infusion was not started. The infusion pump was placed 30 cm above the patient. Several minutes after connecting the prefilled propofol syringe, the patient became drowsy and did not respond to verbal commands. The patient soon became apnoeic, and mask ventilation was started immediately.
Upon examination, we found that some of the propofol in the syringe had been replaced with air. We immediately checked the infusion pump, but the plunger rod of the glass syringe had not moved at all. We removed the prefilled propofol syringe and the infusion line and determined that approximately 200 mg of propofol had been injected into the patient. Twenty-five minutes after the patient lost consciousness, he recovered fully without any neurological symptoms. Thereafter, surgery was performed under total i.v. anaesthesia using another prefilled propofol syringe and epidural block, as scheduled and without further incident.
The affected syringe was sent to AstraZeneca for further examination. The prefilled propofol syringe has a rubber plug at the spigot to attach it to a Luer connector. Inspectors reported that the outside of the rubber plug in this case contained a single hole made by the connector needle, and the inside had a cleft approximately 1.1 mm wide. They also found a mark on the aluminum seal covering the rubber plug, indicating that the Luer connector might have been connected to the glass syringe at an incorrect angle. The glass syringe was neither broken nor cracked.
During assembly of the Luer connector to the syringe barrel, the user slides a connector over the aluminum seal until it is firmly seated; this positions the connector needle at the centre of the rubber plug. We suspect that the needle of the Luer connector penetrated the rubber plug, making a cleft on the inside of it probably because it was inserted on a slant. This could have caused laceration of the rubber plug, allowing influx of air into the glass syringe around the needle. Accidental propofol infusion would then occur by a siphon effect.
Accidental infusion of propofol can be fatal because it causes severe respiratory depression or hypotension. We offer the following suggestions to help avoid a similar experience:
Nagano, Japan
Acknowledgments
The analysis and technology section, Quality Control Department, Maihara Factory, AstraZeneca (Maihara, Shiga, Japan) examined the affected syringe and provided a report free of charge.
References
1 Kay B, Rolly G. ICI 35868, a new intravenous induction agent. Acta Anaesthesiol Belg 1977; 28: 30316[Medline]
2 Breslin D. Failure of a Diprivan 1% prefilled propofol syringe. Anaesthesia 2000; 55: 10301
3 Ward MM, Browne B, Lim YS. Failure of prefilled propofol syringe. Anaesthesia 2003; 58: 3945[ISI][Medline]