anesthesia work station to anesthesiatisel

anesthesia machine with pneumatic and mechanical components .
safety features
vaporizers, monitors
scavanging system

1. Anaesthesia machine-1

2. NO EQUIPMENT IS MORE INTIMATELY ASSOCIATED WITH THE PRACTICE OF ANAESTHESIOLOGY THAN THE ANAESTHESIA MACHINE 

3. Anaesthesia Workstation An anesthesia workstation integrates most of the components necessary for administration of anesthesia into one unit It is a device which delivers a precisely-known but variable gas mixture, including anaesthetizing and life-sustaining gases. Consists of: The anesthesia machine Ventilator Breathing system Scavenging system Monitors Added to this may be drug delivery systems, suction equipment, and a data management system

4. History The original concept of Boyle's machine was invented by the British anaesthetist H.E.G. Boyle in 1917 1920 – A vapourizing bottle is incorporated to the machine. 1926 – A 2nd vaporizing bottle and by-pass controls are incorporated. 1930 – A Plunger device is added to the vaporizing bottle. 1933 – A dry-bobbin type of flowmeter is introduced. 1937 – Rotameters displayed dry-bobbin type of flowmeters

5. Types of Anesthesia Machine Intermittent -Gas flows only during inspiration Egs : Entonox apparatus, Mackessons apparatus Continuous -Gas flows both during inspiration and expiration. Egs : Boyle Machine Forregar Dragger

6. Standards for Anesthesia Machines and Workstations Standards for anesthesia machines and workstations provide guidelines to manufacturers regarding their minimum performance, design characteristics, and safety requirements. During the past 2 decades, the progression of anesthesia machine standards has been as follows: 1979: American National Standards Institute 1988: American Society for Testing and Materials, 1994: ASTM F1161-94 (reapproved in 1994 and discontinued in 2000) 2005 : International Electrical Commission (IEC) 2005 : ASTM (reapproved)F1850 European standard is EN740

7. Contd…. To comply with the 2005 ASTM F1850-00 standard, newly manufactured workstations must have monitors that measure the following parameters: continuous breathing system pressure, exhaled tidal volume, ventilatory CO2 concentration, anesthetic vapor concentration, inspired oxygen concentration, oxygen supply pressure, arterial hemoglobin oxygen saturation arterial blood pressure, and continuous electrocardiogram.

8. Contd… The anesthesia workstation must have a prioritized alarm system that groups the alarms into three categories: high, medium, and low. These monitors and alarms may be enabled automatically and made to function by turning on the anesthesia workstation, or the monitors and alarms can be enabled manually and made functional by following a pre-use checklist.

9. Basic Schematics

10. System components Electrical Pneumatic 1.Master Switch 2.Power Failure Indicator 3.Reserve Power 4.Electrical Outlet 5.Circuit Breakers 6.Data Communication Port 1.High Pressure System 2.Intermediate System 3.Low Pressure System

11. Electrical Components Master Switch Master (main power) switch activates both the pneumatic and electrical functions . On most machines, when the master switch is in the OFF position, the only electrical components that are active are the battery charger and the electrical outlets Standby position - allows the system to be powered up quickly Computer-driven machines should be turned OFF and restarted with a full checkout at least every 24 hours. STANDBY mode is not used for an extended period.

12. Most machines are equipped with a visual and/or audible indicator to alert the anesthesia provider to the loss of mains power . The machine will usually give an indication when mains power is lost. Power Failure Indicator

13. Reserve Power Backup source of power for the occasional outage is necessary. The anesthesia provider should check the battery status during the preuse checkout procedure. While some older anesthesia machines used replaceable batteries, most new machines use rechargeable batteries. It usually takes a number of hours to fully recharge a battery after it has completely discharged.

14. Electrical Outlets Most modern anesthesia machines have electrical outlets. These are intended to power monitors and other devices. As a general rule, these outlets should only be used for anaesthesia monitors. Other appliances should be connected directly to mains power. Next to each outlet is a circuit breaker.

15. There are circuit breakers for both the anesthesia machine and the outlets . When a circuit breaker is activated, the electrical load should be reduced and the circuit breaker reset Circuit Breakers Data Communication Ports Most modern anesthesia machines have data communications ports. These are used to communicate between the anesthesia machine, monitors, and the data management system

16. Gases are supplied under tremendous pressure for the convenience of storage and transport. The anaesthesia machine receives medical gases from a gas supply; controls the flow of desired gases reducing their pressure, to a safe level. So the pressure inside a source ( cylinder or pipeline ) must be brought to a certain level before it can be used for the purpose of ventilation. And it needs to be supplied in a constant pressure, otherwise the flow meter would need continous adjustment.

17. This is achieved by bringing down the pressure of a gas supply in a graded manner with the help of three pressure reducing zones . Thus the pneumatic part of the machine can be conveniently divided into three parts- high ,intermediate and low pressure systems

18. Consists of: Hanger Yolk Check valve Cylinder Pressure Indicator (Gauge) Pressure Reducing Device (Regulator ) Usually not used, unless pipeline gas supply is off

19. Hanger Yoke Assembly The Hanger yoke assembly 1) Orients and supports the cylinder 2) Provides a gas-tight seal 3) Ensures uni -directional gas flow The workstation standard recommends that there be at least one yoke each for oxygen and nitrous oxide. If the machine is likely to be used in locations that do not have piped gases, it is advisable to have a double yoke, especially for oxygen.

20. Body It is threaded into the frame of the machine. It provides support for the cylinder(s). Commonly the swinging gate type is used. When a cylinder is mounted onto or removed from a yoke, the hinged part can be swung to side.

21. Retaining Screw It is threaded into the distal end of the yoke. Tightening the screw presses the outlet of the cylinder valve against the washer and the nipple so that a gas tight seal is obtained. The cylinder is then supported by the retaining screw, the nipple, and the index pins. The conical point of the retaining screw is shaped to fit the conical depression on the cylinder valve.

22. Nipple It is a part of the yoke through which the gas enters the machine. It fits into the port of the cylinder valve. If it is damaged, it may be impossible to obtain a tight seal with the cylinder valve .

23. These are situated below the nipple. These help to prevent mounting of incorrect cylinder to yoke. The holes into which the pins are fitted must be of a specific depth. If they extend too far into the body of the yoke, it may be possible to mount a incorrect cylinder. Index Pins

24. Bodok seal -cylinders are fitted with yoke with a sealing washer called BODOK SEAL It is made up of non combustible material and has a metal periphery which make it long lasting. It should be less than 2.4mm thick prior to compression. only one seal should be use between the valve & yoke

25. Caution!! The wrong Cylinder may be fitted by: Using extra sealing washers Removing of/ Wearing of the Index Pins Placing an inverted gas cylinder

26. Filter It is used to prevent particulate matter from entering the machine. It is to be placed between the cylinder and the pressure reducing device. Filter

27. Placing cylinder in yoke Placing a Cylinder in a Yoke 1.Cylinder valves and yokes not be contaminated with oil or grease 2. Persons placing a cylinder in a yoke should always wash their hands first 3. Pin Index Safety System pins are present 4. Retract the retaining screw 5. The washer is placed over the nipple 6.T he cylinder is supported by the foot and guided into place manually 7. The port on the cylinder valve is guided over the nipple and the index pins engaged in the appropriate holes 8. The retaining screw is tightened 9. Do not insert the screw in the safety relief device 10. Make certain that the cylinder is full and that there is no leak

28. Check Valve Assembly

29. It allows gas from a cylinder to enter the machine but prevents gas from exiting the machine when there is no cylinder in the yoke. It allows an empty cylinder to be replaced with a full one without having to turn off the `in–use` cylinder. Prevents transfer of gas from one cylinder to the other with a lower pressure in a double yoke. It consists of a plunger that slides away from the side of the greater pressure.

30. It is not designed to act as a permanent seal for empty yoke and may allow small amount of gas to escape. As soon as a cylinder is exhausted it should be replaced by a full one or a dummy plug.

31. In order to minimize losses – Yokes should not be left vacant for extended periods An empty cylinder should be replaced as soon as possible An yoke plug can be used to prevent gas leak or An empty cylinder can be left behind after closing the valve

32. A Bourdon tube is a hollow metal tube ( copper alloy) bent into a curve, then sealed on one side and linked to a clock like mechanism

33. Safety features in Cylinder Pressure Indicator Gauge is usually color coded. Name and symbol of gas are written over dial. If bourdon tube ruptures gas is vented from back side Gauges are angled and placed in such a way that it can be easily read by anesthetist. Instructions like “use no oil’’ “open the valve slowly’’ are written on the gauge

34. Electronic Cylinder Pressure Indicator Light emitting diodes(LED’S)in electronic pressure gauge indicate Cylinder valve is close –Dark color Cylinder valve is open – Pressure adequate – Green Pressure inadequate- Red

35. Pressure Reducing Device (Regulator)

36. The pressure in a cylinder varies. The anesthesia machine is fitted with devices (reducing valves, regulators, reducing regulators, reduction valves, regulator valves) to maintain constant flow with changing supply pressure. These reduce the high and variable pressure found in a cylinder to a lower ( 40 to 48 psig, 272 to 336 kPa ) and more constant pressure suitable for use in an anesthesia machine. The machine standard requires reducing devices for each gas supplied to the machine from cylinders. Physical Principle- A large pressure acting over a small area is balanced by a small pressure over a larger area

37. Pressure regulators have safety relief valves If due to any reason there is build up of pressure in pressure regulator then the safety valve blow off at a set pressure of 525 k pa(70psi) Safety features on pressure regulator