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  1. What is the difference between piston and pneumatic ventilators?
    • Pneumatic requires a drive gas to drive bellows
    • Piston system does not use a drive gas, so may be used on backup tank
  2. At what pressures are positive and negative safety valves opened on piston ventilator?
    • >75 +/-5cmH2O positive pressure relief valve opens
    • < - 8cmH2O negative pressure relief valve opens
  3. What does the negative pressure relief valve do on the piston ventilator?
    • 1) prevents NEEP
    • 2) allows room air to be drawn in
  4. How is gas delivered in volume controlled mode?
    • Driving gas flow stops at set tidal volume delivered to breathing circuit
    • Or Pmax is reached
  5. How is gas delivered in pressure controlled mode?
    • Target pressure is set and maintained for certain time period
    • The delivered tidal volume varies depending on compliance
  6. What is the difference between ascending and descending bellows?
    • Describes what the bellows do during EXPIRATION
    • Descending have potential for NEEP
    • Ascending always have some amount of PEEP due to weight of bellows
  7. Why are ascending bellows safer than descending?
    They do not fill if there is a disconnect
  8. What is the function of the spill valve in the bellows?
    • Opens if set pressure is exceeded to vent gas into WAG system
    • It will open at any point if peak pressure is exceeded
  9. At what pressure does spill valve open?
  10. What is the most common course of action with ventilator alarms?
    • Switch to manual ventilation
    • Increase gas flow
    • Check patient and system
  11. Pressure below threshold for how long will signal apnea/disconnect alarm?
    15-30 seconds
  12. What can the reverse flow alarm indicate?
    Incompetent expiratory valve
  13. What is a good ventilator mode for difficulty ventilating?
  14. What does PSV require?
    Spontaneously breathing patient
  15. What does PSVPro do in the event of apnea?
    Switch to backup mode (SIMV on our machine)
  16. In PSVPro backup mode, what happens when spontaneously breathing resumes?
    Switches back to PSV mode
  17. What are typical adult settings for VCV?
    • TV 10ml/kg
    • Rate 6-12
    • PEEP 0 to start
  18. What does the PIP alarm in VCV alert you to?
    • Pt bucking
    • Obstructed circuit
    • Obstructed airway
  19. What is the course of action for asynchronous breathing in VCV?
    • 1) turn vent off
    • 2) hand ventilate
    • 3) remedy the situation
    • Patients are almost always light
    • If 1,2,3 doesn't work, disconnect circuit and ambu pt, call for help, switch to TIVA
    • Still difficult, look at what is going on in the airway
  20. What is the typical peak airway pressure alarm setting for relatively healthy adults in VCV?
  21. What types of patients is PCV indicated for?
    LMAs, emphysema, neonates and infants
  22. What types of patients have poor airway compliance and require higher volumes?
    • Pregnancy
    • Laparoscopic surgeries
    • Morbid obesity
    • ARDS
  23. What are typical adult settings for PCV?
    • 1) pressure limit 20cmH2O
    • 2) rate 6-12
    • 3) PEEP 0 to start
    • This is also good to start for pediatrics
  24. How is pressure limit affected by PEEP in PCV?
    PC at 20, 5 of PEEP, inspiratory pressure is 25
  25. What is less likely to occur in SIMV?
    Asynchronous breathing
  26. What is unique about SIMV?
    • Detects spontaneous breaths (if any)
    • Delivers controlled breaths in synch with the patient's inspiratory effort
    • Helps maintain minute ventilation avoiding breath-stacking or bucking
  27. What is the trigger window in SIMV?
    Percentage of expiratory pause the vent monitors for patient effort
  28. What is sensitivity in SIMV?
    How much negative inspiratory force the pt must generate to trigger a breath (l/min)
  29. How does PCV-VG work?
    • Ventilator operates in PCV with a target tidal volume
    • Dynamically adjusts inspiratory pressure until target tidal volume reached
    • Does not exceed maxium set Pmax
  30. What type of surgeries is PCV-VG good for?
    Laparoscopic surgeries
  31. What advantages does PCV-VG offer?
    • Control of PIP - basic PCV mode
    • Control of arterial oxygenation - guaranteed tidal volume
    • Good default for most machines
  32. What anesthesia considerations are there for ARPV?
    Pt will remain on ICU vent and will do TIVA
  33. What is the concept behind APRV?
    • Vent cycles between 2 levels of CPAP
    • High pressure and low pressure correlate to high volume and low volume
  34. Where does gas exchange occur during APRV?
    • When pressure is intermittently released to lower pressure
    • 1) waste gases eliminated
    • 2) oxygenation occurs
  35. What is the normal I:E ratio?
  36. How does I:E ratoi change in SIMV?
    It changes as you change the rate
  37. In what patients would an increased expiratory phase be beneficial?
    • Obstructive lung disease
    • 1) COPD
    • 2) Emphysema
  38. When is institution of PEEP recommended?
    • 1) PaO2 cannot be kept >60mmHg
    • 2) FiO2 at 50%
  39. What are 3 hazards of PEEP?
    • 1) decreased cardiac output
    • 2) pulmonary barotrauma
    • 3) increased extravascular lung water due to obstructed pulmonary lymph flow
  40. Why is 4l/min FGF common?
    From days when safety margin was needed for less accurate flowmeters and vaporizers
  41. What FGF functions essentially the same as a nonrebreather mask?
    • 5-8 lpm
    • 1-1.5 times minute ventilation
  42. When should high FGF (5-8lpm) be used?
    • Preoxygenation
    • Induction
    • Emergence
  43. When should low FGF (0.5-2lpm) be used?
    During maintenance of anesthesia
  44. What agent requires that you not use FGF <1 lpm for > 2 MAC hours?
  45. What is a key disadvantage of low FGF?
    • Accumulation of undesired gases in closed circuit
    • Acetone, CO, methane, hydrogen, ethanol, anesthetic agent metabolites, argon, nitrogen
  46. What is the most significant factor in promoting adequate denitrogenation?
    Good mask seal
  47. What is the most common site of disconnection?
  48. What is the most common preventable equipment-related cause of mishaps?
  49. What must be used to guard against disconnects?
    Either ETCO2 or precordial stethascope
  50. Can you silence apnea alarms?
  51. What is the biggest problem with ventilators?
    Failure to initiate ventilation or resume after pause
  52. What is the most important monitor for disconnection?
    Precoridal because it's alarms cannot be inactivated like ETCO2
Card Set:
2014-07-13 01:12:16
IHS Test 3
IHS Ventilator
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