Sudden blackout of the Dräger Zeus Anaesthetic Machine Dr Tse, Yee Wah Dr Koo, Chi Kwan Dr Tan, Song Tuen Dr Chan, Yau Wai Queen Elizabeth Hospital, Hong Kong Background Ventilator failure is not an uncommon incident in operating theatres Dräger Zeus Anaesthetic Machine failure: not been reported before Background TCA(TM) = Target-Controlled Anesthesia automatic control of gas dosages manual control touch screen Drager Zeus Anaesthetic machine Incident elective hepatectomy Dräger Zeus Anaestehtic machine failure: unresponsive touch screen & rebooted subsequently laid by standby screen shortly after diathermy usage Incident Patient disconnected from ventilator, ventilated by manual resuscitator Dräger Zeus ventilator was replaced by Dräger Narkomed IV photos were taken to record the setup layout for later investigation Incident Preliminary examination by the Dräger Company: no external defects or damages PASS: Self test, gas delivery, ventilatory test analysis of the device status report: USB port error of the device computer in the ventilator (1) Power cord of electric blanket & (2) data cable Postulation Electrical interference rebooted shortly after the use of diathermy Where? Between diathermy & electric blanket (the only device that was plugged to the auxiliary power socket of the ventilator) data transmission in USB port was affected Simulation Devices: (1) Dräger Zeus (2) Conmed 6400 (argon beam coagulator) (3) Cusa 200 (ultrasonic surgical aspirator) (4) Force FX (diathermy) (5) KanMed 202W (electric blanket control unit) (6) HP monitor OWON oscilloscope LEM HEME LH240 ammeter Simulation (1) Power cord of electric blanket & (2) data cable Diathermy use on pork (1) Oscilloscope & (2) Ammeter connected to power cord To prove the postulation… 1. 2. 3. 4. 5. Control (no diathermy): no failure Diathermy in cutting mode: no failure Diathermy in coagulation mode: FAILURE without data cable connection: no failure with use of optical relay: no failure Discussion – 2 circuits Discussion Capacitive coupling in any eletrosurgery: high frequency current in a conductor can induce current in another conductor separated by an insulator Conductors: diathermy tip & metal wirings in electric blanket Insulator: gel pad Discussion – why coagulation mode? Why diathermy in coagulation mode? Discussion Scenarios / Parameters Voltage (V) Current (A) Frequency (Hz) Control Cutting mode (90W) 8 16 0.76-1.13 0.15-0.42 50 Out of range Coagulation mode (90W) 86.4 0.15-0.58 28600 Discussion without data cable connection: no failure with use of optical relay: no failure Solutions Do not use the auxiliary power socket in the Dräger Zeus Use of an optical signal relay (to interrupt the passage of electric interference via the USB port of the device computer) Learning points Electrical safety is an important issue in OT Proper connection of each device requires an anesthetist’s attention any electrical fault can lead to potential/ actual crisis References Myerson, K R. Potential hazard of East-Radcliffe ventilator. Failure to entrain adequate oxygen. Anaesthesia. 40(3):2857, 1985 Mar. Williams DJ. Ventilator failure due to non-ISO-standard components. [Case Reports. Letter] Anaesthesia. 56(4):392-3, 2001 Apr. Sosis MB. Drager ventilator failure on changing the respiratory rate setting.[see comment]. [Case Reports. Letter] Anesthesia & Analgesia. 76(2):453-4, 1993 Feb. Ananthanarayan C. Fisher JA. Drager ventilator failure.[comment]. [Comment. Letter] Anesthesia & Analgesia. 77(3):638, 1993 Sep. Barahal D. Sims C. Ventilator failure during use of a new anesthesia machine. [Letter] Anesthesiology. 95(2):568-9, 2001 Aug. Rafael A. Ortega, M.D.,* Bruce Vrooman, M.D., Rania Hito, M.S. Another Cause for Ventilator Failure. Anesthesiology 2006; 104:1351 Ortega RA. Zambricki ER. Fresh gas decoupling valve failure precludes mechanical ventilation in a Draeger Fabius GS anesthesia machine. [Case Reports. Letter] Anesthesia & Analgesia. 104(4):1000; discussion 1000-1, 2007 Apr. Photo of Dräger Zeus ventilator from http://medgadget.com/archives/2006/04/zeus_anesthesia.html Photo of electric blanket from User Manual Kanmed Operatherm 202 www.kanmed.se/download/download_files/operaterm/op-202-050_vers5_uk.pdf Haag R. Cuschieri A. Recent advances in high-frequency electrosurgery: development of automated systems. [Review]. Journal of the Royal College of Surgeons of Edinburgh. 38(6):354-64, 1993 Dec. Force FXTM Electrosurgical Generator Technical Specifications http://www.valleylab.com/product/es/generators/pdf/Lforcefx.pdf (page 4) Tucker RD. Voyles CR. Laparoscopic electrosurgical complications and their prevention. [Review] [16 refs] [Case Reports. Journal Article. Review] AORN Journal. 62(1):51-3, 55, 58-9 passim; quiz 74-7, 1995 Jul.