1. Renaissance in Anesthesia Machine Safety
The Modern Anesthesia Machine (Workstation) & Anesthesia Delivery Unit (ADU): Improved Safety Features
Charles G. McCombs, Jr. CRNA, BSA

2. Morton’s Ether Inhaler (1846)
Wm. T. G. Morton
For centuries, man searched for substances to relieve pain. But it wasn’t until the mid 19th century that substances such as diethyl ether and chloroform were shown to be capable of relieving surgical pain. In 1846, Wm T.G. Morton successfully anesthetized
Morton’s Ether Inhaler (1846)

3. Civil War Era Anesthesia
Chisholm Chloroform Inhaler
Ether Cone
Civil War Era Anesthesia

4. The Teter Anesthesia Machine (1903)
Pioneers
The Teter Anesthesia Machine (1903)
1903 – Charles K. Teter, DDS
Jay Heidbrink DDS
Samuel S. White DDS
Dr. Henry Edmund Gaskin Boyle
First Anesthesia Machine
(Boyle Machine)
British Anesthetist Dr. Henry Edmund Gaskin Boyle is credited (by whom is unknown) with inventing the first anesthesia machine in 1917 known as the The Boyle Machine
The Teter machine – developed a machine to deliver compressed N2O, O2
The Boyle Machine (1917)

5. No. American Drager 2A (c1986)
Ohio Medical
(1966)
No. American Drager 2A (c1986)

6. 1979 American National Standards Institute (ANSI)
ANSI Z-79 Committee
Machine Standards
Failsafe Valve & Alarm
Vaporizer Lockout
DISS Connections
PISS Connections
Active Regulators
Legible & Visible Gauges
1979 American National Standards Institute (ANSI)

7. 1988 American Society For Testing and Materials (ASTM)
ASTM F-29 Committee
ASTM F
Preuse Checkout Procedures
Proportioning Device
Concentration Calibrated Vaporizers
Integral O2 Analyzer
Master Switch Enabled Alarms
Hierarchical Alarm Prioritization
1988 American Society For Testing and Materials (ASTM)

8. The Modern Anesthesia Workstation
No. American Drager
Julian
Datex Ohmeda (GE Health Care)
Aestiva 5
Fabius GS, Apollo, and Narkomed 6000 (Divan) piston ventilators
S/5 ADU incorporates Electronically controlled Aladdin Cassettes
The Modern Anesthesia Workstation

9. The Modern Anesthesia Workstation
GE Health Care
ADU/5
ADU/5 Aladin Cassette Vaporizers
The Modern Anesthesia Workstation

10. “Brain Damage & Death Related to Anesthesia Machines” (Caplan, 1997)
RA Caplan (1997) - Study of 3791 Closed Anesthesia Claims (1962 – 1991)
72 claims related gas delivery system
Claim frequency decreased from 2.2% to 1.2% from 1985 – 1991
Pure equipment failures were rare
Rate of equipment misuse, 3 x higher than pure failures
76% of claims – Death or Brain Damage
78% of injuries could have been prevented by better monitoring
Caplan,RA, Visica, MF, Posner, KL, Cheney, FW Adverse anesthetic outcomes arising from gas
delivery equipment; a close claims analysis. Anesthesiology 1997;87:741-8

11. Specific Damaging Events (Caplan, 1997)
Breathing Circuit (39%) - The #1 Culprit
Caused 70% of the incidence of death & Brain Damage
Most Frequent Circuit Event – Disconnects or misconnects leading to hypoventilation or barotrauma
Vaporizers (21%)
Overdose or awareness
Gas analysis or cerebral monitoring may have prevented
Ventilators (17%)
Improper activation or excessive Vt /Inspiratory pressure

12. Specific Damaging Events (Caplan, 1997)
High Pressure Gas Supplies (11%) – direct connection to respiratory system w/o proper decompression
Human Error – 3 times more common than failure of equipment
Failure to precheck
Unfamiliarity with equipment
Lack of Vigilance
Unauthorized repair or “jury rigging”
Caplan,RA, Visica, MF, Posner, KL, Cheney, FW Adverse anesthetic outcomes arising from gas
delivery equipment; a close claims analysis. Anesthesiology 1997;87:741-8

13. Conventional v.s. Modern Anesthesia Machines
Conventional Machines
Modern Machines
North American Drager - Narkomed Series (2A, 2B, 3, 4, & GS)
Ohmeda - Modulus & Excel
Drager Medical – Fabius GS v1.3, Julian, Apollo, Narkomed 6400
Datex-Ohmeda – Aestiva/5 (assuming 7900 ventilator),
Anesthesia Delivery Unit (ADU) (assuming S/5 monitor system)

14. Limitations of the Conventional Machine
Numerous External Connections
Barotrauma Protection (Manually Set Pressure Limiters)
Vaporizer Risks
Lack of Advanced Ventilator Features
Inaccurate Delivery of Set Tidal Volumes (Vt)
Manual Preuse Checkout Procedures
Lack of Integrated Information Systems
Poor Low-Flow Adaptation
Compressed Gas Consumption

15. The Modern Machine Addresses Limitations
Reduced External Connections
Internal Modular Design (Aestiva/5) or Manifold Components (Julian)
Electronically Controlled PEEP and Open Reservoir Scavenging

16. Electronic Vaporizer Cassettes
ADU, Aladin Cassettes (GE Healthcare)
Electronically Control & Measure Vaporization
Eliminates need for multiple vaporizers
Color Coded, magnetically labeled
Agent delivery reported to Information Management System (IMS).
Overfill protection
Automatically leak tested
Check valve protection for bypass circuit

17. Piston Driven Ventilators (Drager Medical)
Fabius GS
Narkomed 6400 Divan

18. Modern Ventilators
“Conventional” Dual Circuit, Pneumatic Drive “SmartVent” (GE Healthcare)
Single Circuit Electronic Piston Drive Divan or Fabius GS (Drager Medical)
Allows Flexibility in ventilation
Pressure Control Ventilation (PCV)
Volume Control Ventilation (VCV)
Pressure Support Ventilation (PSV)
Synchronized Intermittent Mandatory Ventilation (SIMV-Vol & SIMV-PC)

19. Modern Ventilators
Methods to Assure Accuracy in Delivery of set Tidal Volumes (Vt)
Fresh Gas Decoupling (FGD)
Compliance Testing and Compensation
Leak Testing/Measurement and Reporting
Location and Electronic Activation of PEEP
Electronic Settings Reduce Operator Error
One-step activation of Control Mode Ventilation (CMV)

20. Automated Checkout Procedures and Monitoring
User cannot Circumvent
Multitude of Surveillance Alarms
Critical Systems Checked
Computer Circuit Loops
Flow Meters
Pressure Sensors
Piston Drive Gears
Coordination /operation of Valves
Compliance Compensation
Fresh Gas Control
Display of Ventilation & Airway Pressures
The operator can not test these tolerances manually by conventional checkout procedures. While the machine can be used with abbreviated test procedures for emergencies, eventually the meachine can not be used till retested.

21. Information Management Systems (IMS)
Integrated Systems exceed ASTM Standards
Integrated Physiological and Respiratory Monitoring Data
Digital Fresh Gas & Volatile Agent Flow Data (Inspired & Expired Concentration)
Data Exported to Anesthetic Record
Data MAY be Exported to other Demographic and Financial Records

22. New Machines; New Concerns
Operator Learning Curve - even less understanding of machine functions)
Over reliance on Technology – Are you sure it will tell you all that fails?
Dependence on Electricity - How does your machine function in a power failure?
Piston Ventilators – quiet, hidden – Will you know if the piston fails to move?

23. New Machines; New Concerns
Can a machine have a clinically significant failure after passing an automated checkout?
The new machines still do not warn of oxygen consumption from open cylinders if wall pressures drop

24. New Solutions to Old Problems Raises New Questions!!!