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Dr Tse, Yee WahDr Koo, Chi Kwan
Dr Tan, Song TuenDr Chan, Yau Wai
Queen Elizabeth Hospital, Hong Kong
Sudden blackout of the Dräger Zeus Anaesthetic Machine
Ventilator failure is not an uncommon incident in operating theatres
Dräger Zeus Anaesthetic Machine failure: not been reported before
Background
Background
TCA(TM) = Target-Controlled Anesthesia automatic control of gas dosagesmanual controltouch screen
Drager Zeus Anaesthetic machine
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
Incident
(1) Power cord of electric blanket & (2) data cable
Electrical interference rebooted shortly after the use of diathermyWhere? 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
Postulation
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 monitorOWON oscilloscopeLEM 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. Control (no diathermy): no failure2. Diathermy in cutting mode: no failure3. Diathermy in coagulation mode: FAILURE4. without data cable connection: no failure5. with use of optical relay: no failure
Discussion – 2 circuits
Discussion
Capacitive coupling in any eletrosurgery:
high frequency current in a conductor caninduce 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 8 0.76-1.13 50Cutting mode (90W)
16 0.15-0.42 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):285-7,
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
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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].
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Journal Article. Review] AORN Journal. 62(1):51-3, 55, 58-9 passim; quiz 74-7, 1995 Jul.