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

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.