BMET Quiz 2

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vritte
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BMET Quiz 2
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2014-10-23 15:01:25
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BMET Quiz 2
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  1. What is the different output between monophasic and biphasic?
    Monophasic has 40% higher output and sends a positive change through the heart where biphasic sends a positive charge across one way then a negative charge across the other.  
  2. What are the advantages of biphasic?
    achieves defibrillation in fewer attempts using lower energies in each attempt

    less time delay in salvaging a cardiac crisis and less damage to the heart
  3. How is an AED different from a full-function defibrillator?
    An AED (Automatic External Defibrillator) is a semi-automated defib. that analyzes cardiac status, then delivers a therapeutic shock indicated by using a pre-set algorithm and voice commands.  

    intended for non-clinical settings by non-clinicians

    typical biomed maintenance consists of functional check and battery check
  4. What is cardioversion?
    A mode of some defibs that ensure that the delivery of shock pulses are timed immediately after the R wave and before the start of the T-wave.
  5. How is a defib. used in/for cardioversion?
    a small energy pulse from a defib is used to convert a non-lethal arrhythmia (atrial flutter) to a normal sinus rhythm.

    delivers a pulse about 30ms after the peak of the R-wave.  
  6. what is asynchronous?
    An asynchronous pacer fires at a fixed rate at pre-set intervals independent of cardiac activity
  7. what is synchronous?
    pacing that is in "demand" mode.  a pacer fires only when no complex is sensed for predetermined amount of time
  8. what is the difference between asynchronous and synchronous pacing?
    asynchronous fires pulse independent of cardiac activity and synchronous fires pules only when no complex is sensed for a predetermined amount of time.
  9. what are the essential sections of a linear power supply?
    • Transformer (step up/step down AC voltage)
    • Rectifier (convert AC V to DC V)
    • Filter
    • Regulation (voltage regulator +78xx & -79xx series)
    • TO-220
    • TO-3 Packs
    • Protection
  10. what are the advantages of a linear power supply
    electronically simple, inexpensive, can tolerate transients & spikes
  11. what are the disadvantages of a linear power supply?
    inefficient, heavy and hot
  12. what are the essential sections of a switching power supply?
    • input rectifier
    • filter (ac rectified to dc then filtered)
    • inverter (chopper - dc fed to switching transistors that chop into high freq. sq. waves)
    • output transformer (high-frequency sq. wave fed to a transformer that steps it down)
    • DC output (low voltage then rectified and is filtered as the output)
  13. what are the advantages of a switching power supply?
    • very efficient (draws current only when needed)
    • light
    • runs cool
  14. what are the disadvantages of a switching power supply?
    • more expensive
    • less tolerant of overloads
    • potentially higher failure rate
  15. what is cell voltage?
    default voltage of a cell
  16. what is load current
    battery output current under a load
  17. what are amp-hours
    the amount of time a battery is able to supply current
  18. Voltage of alkaline cells
    1.5V
  19. Voltage of lithium cells
    3V
  20. Voltage of sealed lead-acid in a secondary cell
    2V
  21. Voltage of nickel metal-hydride in a secondary cell
    1.2V
  22. what are the features of a smart battery
    rechargeable battery that includes a microchip that communicates info to the charger and user
  23. what does the smart bus tell on a smart battery
    • battery voltage
    • temperature
    • clock data
    • battery type
    • birthdate
    • serial number
    • cycle count as binary data
  24. list the three safety references for biomed
    • NFPA-99
    • IEC 60601-1
    • IEC 62353
  25. Explain what the safety reference is for the NFPA 99
    Patient Care Vicinity: patient care area where a procedure is performed that is normally subject to wet conditions while patient is present, including standing fluids on the floor or drenching of the work area either of which is intimate to the patient or staff

    typically applies to surgical suites and other areas

    • 1.5m (~6ft) around patient bed
    • 2.5m (~7.5ft) from floor
  26. Explain what the safety reference is for the IEC 60601
    Applied Parts of medical equipment:

    Types: B (Body), BF (Body Float) and CF (Chest Float

    Type B: applied parts that are generally not conductive and can be immediately released from the patient.  May be grounded.  eg: Non-invasive BP monitors

    Type BF: Devices that have direct contact with the patient or parts that have long term contact with the patient.  eg: ECG monitors

    Type CF: Applied parts that have direct contact with the heart.  eg: invasive pressure monitors, defibrillator paddles
  27. Explain what the safety reference is for the IEC 62353
    similar to IEC 60601-1 but looser requirements and is written for end-users
  28. what are the color codes for the US and IEC in power cords
    • U.S.:

    • Neutral - White
    • Hot - Black
    • Ground - Green/Green w/ yellow

    IEC:

    • Neutral - Blue
    • Hot - Brown
    • Ground - Green/Green w/ yellow
  29. In applied parts ratings what does B mean
    Type B: applied parts that are generally not conductive and can be immediately released from the patient.  May be grounded.  eg: Non-invasive BP monitors
  30. In applied parts ratings what does BF mean?
    Type BF: Devices that have direct contact with the patient or parts that have long term contact with the patient.  eg: ECG monitors
  31. In applied parts ratings what does CF mean?
    Type CF: Applied parts that have direct contact with the heart.  eg: invasive pressure monitors, defibrillator paddles
  32. In applied parts ratings what is the icon for B
    body
  33. In applied parts ratings what are the icons for BF
    body in box outline
  34. In applied parts ratings what are the icons for CF?
    heart in box outline
  35. IEC 60601 safety limits:
    Class I:  Device is protected against shock by use of a grounding wire connected to the exposed conductive parts of the device.

    Class II:  Device is protected by additional insulation in addition to the basic design insulation.  Usually called "Double Insulation".  
  36. What are the safety limits for leakage current to the chassis
    300 micro amps
  37. In IEC 60601, what are the safety limits for leakage current in any ECG lead
    10 micro amps (ground closed)

    50 micro amps (ground open)
  38. In IEC 60601, what are the safety limits for leakage current in all ECG leads together
    10 micro amps (ground closed)

    50 micro amps (ground open)
  39. In IEC 60601, what are the safety limits for resistance from ground to chassis
    500 milli ohms (0.5 ohms)
  40. how do you safely check a multi-device "system"
    refers to a number of medical devices commonly used together which share a common power strip.  

    Generally the electrical safety check of a system can be done at the common power cord that feeds it.

    be certain that the total current draw of the system, when at maximum, does not exceed ~75% of the power strip’s rating.
  41. how do you safely check a totally insulated device
    Use foil on each side of the device that is attached to the testing leads to check for leakage current
  42. Isolated power system
    Generally used in operating rooms ...

    consists of an isolation transformer with neutral ground connection deliberately omitted and a line LIM

    reduces shock hazard in wet locations

    continuity of power (for life support devices...etc)

    advanced warning of equipment when error occurs.
  43. what is a line isolation monitor
    gives a reading of how much "connection" there is between the supposedly isolated wall power wires, and earth ground. 

    The "connection" should be below 2milliAmps (mA).  

    Line Isolation Monitor may be built into the circuit breaker box for the O.R. and will have a remote alarm portion located somewhere in your operating room if the circuit breakers are outside your OR), or may be on the wall in the OR.
  44. how to safely use an extension cord?  where/when can you use one
    They use wire that exceeds current capacity of the power outlet being extended. 

    (usually 14 gauge or 12 gauge, + ground)

    Designed with medical-grade components.
  45. how to safely use an relocatable power taps?  where/when can you use one
    Standardized in UL #1363.  Allowed by NFPA 99, IF:

    -  made of medical grade components

    -  of adequate ampacity for the need

    -  are inventoried and maintained
  46. when is an electrical safety check required?
    on any inspection of new equipment, rented, borrowed, or donated equipment.  

    Any scheduled performance verification (PM)

    after any repair or modification

    as part of a troubleshooting situation
  47. How to temporarily use a device with excessive chassis leakage?
    connect a redundant ground wire

    or

    go through an isolation transformer in the power input
  48. Understand a pressure transducer?
    Catheter in the artery connects to a transducer

    transducer converts pressure to a voltage signal displayed on a monitor

    at a very slow rate (to avoid clotting @ 300mm Hg pressure), heparinzed saline flows into the catheter.
  49. what is the impact of air bubbles in a pressure transducer setup?
    incorrect readings... false high (under-damped)
  50. What is the importance of leveling the transducer with the heart?
    • Must be zeroed to the patient's heart level to correct offset.  
    • Too high signal will be low
    • Too low signal will be high
  51. Understand pulmonary artery catheters and their placement
    Using Swan-Ganzcatheter

    will be inserted within a distal vein then guided into the Vena Cava into the right ventricle then  into the Pulmonary artery

    At this location, a measurement of the arterial pressure is taken
  52. What are the typical pressures for a CVP
    CVP (Central Venous Pressure) - 0-8 mm HG
  53. What are the typical pressures for a wedge pressure
    PCWP (Wedge Pressure) - 1-10 mm HG
  54. What is the auscultatory blood pressure method
    The "Manual" method:

    the systolic and diastolic pressure values are determined by the onset and disappearance of the Korotkoff sounds.

    Pressure applied by cuff, released at specified rate, vessels then snap open and close (korotkoff sounds) which is observed by clinician via stethoscope.  
  55. what is the oscillometric blood pressure method?
    The "Electronic" method:

    The systolic and diastolic pressure values are determined by the onset and disappearance of pulsations of an artery

    dependent on a good algorithm in the firmware, and reliable components.
  56. what is Riva-Rocci
    The auscultatory blood pressure method (the manual method).
  57. what is DinaMAP
    The Oscillometric method (the electronic method).
  58. what are Korotkoff sounds
    The sounds heard over an artery when blood pressure is determined by the auscultatory method.  

    There are 5 phases when listening to the Korotkoff sounds.  
  59. what are the effects of cuff leaks or tubing kinks?
    If there is a cuff leak the pump will run to try to fill the cuff after a few attempts then shut down.  

    If there is a kink, the cuff will not fill and the pump will turn off because pressure has been reached.

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