C21_Wah Tse

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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
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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.
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