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Renaissance in Anesthesia Machine Safety

Renaissance in Anesthesia Machine Safety. The Modern Anesthesia Machine (Workstation) & Anesthesia Delivery Unit (ADU): Improved Safety Features. Charles G. McCombs, Jr. CRNA, BSA. Wm. T. G. Morton. Morton’s Ether Inhaler (1846). 1860’s. Chisholm Chloroform Inhaler. Ether Cone.

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Renaissance in Anesthesia Machine Safety

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  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. Wm. T. G. Morton Morton’s Ether Inhaler (1846)

  3. 1860’s Chisholm Chloroform Inhaler Ether Cone Civil War Era Anesthesia

  4. Pioneers The Teter Anesthesia Machine (1903) 1903 – Charles K. Teter, DDS Jay Heidbrink DDS Samuel S. White DDS 1917 - Dr. Henry Edmund Gaskin Boyle First Anesthesia Machine (Boyle Machine) The Boyle Machine (1917)

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

  6. 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. ASTM F-29 Committee ASTM F1850-00 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. No. American Drager Julian DatexOhmeda (GE Health Care) Aestiva 5 The Modern Anesthesia Workstation

  9. 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 7900 “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

  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!!!

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