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ABC of ventilator graphics

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ABC of ventilator graphics

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  1. NEONATAL PULMONARY GRAPHICS ART OF VENTILATION IN TO SCIENCE OF VENTILATION Dr Vishram Buche Director, NICU Central India’s CHILD hospital & Research institute, NAGPUR

  2. OBJECTIVES ……….. • How to identify different WAVES and LOOPS ? • and differentiate between normal and abnormal ? • How it helps to identify the mode of Vent ? • How it helps to adjust vent settings / vent circuits ? • How it helps to manage disease pattern ? • I. Progression • 2. Responding to drugs.. • 3. Deterioration • How it helps to identify / quantify the problem? • still many more……..

  3. Measured Parameters…. • Flow • Pressure • Time Calculated Parameters ….. • Volume (as an integration of flow) • Compliance • Resistance • Work of Breathing • Auto-PEEP

  4. Measurement of Flow……… • How it is Measured?....... • 1 Pressure Differential Pneumotachometer • 2 Hot Wire Anemometer • Where it is measured? …. • 1. At ETT • 2. Inside the ventilator

  5. Measurement of Pressure…… • Where is it Measured? • At ETT • In Esophagus • Inside Ventilator

  6. Basics phase variables………….. A. Trigger ……. • What causes the breath to begin? B. Limit …… • What regulates gas flow during the breath? C. Cycle ……. • What causes the breath to end? B C A

  7. The Pulmonary graphics display in two formats……… …………………… Waveforms..!!! …………………….Loops ..!!!

  8. Most Commonly used Waveforms and Loops…… Pressure vs. Time Flow vs. Time Volume vs. Time AND Pressure – volume loop Flow – volume loop Flow - pressure loop…???

  9. Differentiate………….. Spontaneous Breaths…. Mechanical Breaths…. volume Time Pressure FLOW

  10. Types of Waveforms…… Pressure Modes Volume Modes Pressure Flow Volume Time

  11. Pressure Mode Pressure Flow Volume Time

  12. Common features of Scalar WAVE forms….. Scalars…….. on ordinate (vertical), Time…………on Abscissa (horizontal) Time line…BASE line where P, F and V are at zero level (FRC or basal alveolar level) Elevated base line only when CPAP/ PEEP is there.

  13. Common features of Scalar WAVE forms….. Inspiratory phase….Active…. affected by modes of vent. Expiratory phase….Passive NOT affected by mode of vent but by various characteristics of Resp system e.g. Resistance , compliance BUT.. Insp time can affect the duration of exp phase eg. In inverse ratio I:E

  14. Common features of Scalar WAVE forms….. • While analyzing one has to keep in mind general • principles of EXPONENTIAL functions applied to • WAVEFORM graphics • Each waveform has to be analyzed in terms of • Magnitude, • Duration, • Pattern.

  15. FLOW waveform……… Pressure mode Volume controlled PIF Flow Inspiration TE Zero flow TI Time Expiration Spont Br PEF What is flow?? How related to volume??

  16. PRESSURE TIME waveform……… Pressure mode Volume controlled PIP Insp Exp Pressure Spont breath End Ex Pres PEEP Ti TE Time

  17. Inspiratory Tidal Volume VOLUME TIME waveform ………. Pressure mode Volume controlled Expiration Inspiration Volume Spont. TI TE Time

  18. Variations and Abnormalities in waveforms…!!!! FLOW-TIME waveform…………….. PRESSURE – TIME waveform……. VOLUME-TIME waveform………….

  19. P Pressure Modes Pressure Flow Volume Time

  20. FLOW waveform……… Pressure mode PIF Flow Inspiration TE Zero flow TI Time Expiration PEF

  21. Identifies type of ventilation……………………… pressure vs. volume Pressure… Volume….

  22. Abnormalities of Flow waveform……… Inspiratory flow pattern…… I -time 1 2 1 : short 2 : Normal 3 : Prolonged 3 Clinical significance……. ? Affects Tidal volume delivery Optimize Insp time

  23. Fixed I –time.. ……..prolonged Flow termination sensitivity on

  24. FLOW TERMINATION……Inspiratory Cycle Off…… 100% of Patient’s Peak Inspiratory Flow 100% 75% 50% Flow 30% • In the above example, the machine is set to cycle inspiration off at 30% of the patient’s peak inspiratory flow.

  25. Inspiratory Cycle Off…… Exhalation spike A B 100% 100% 60% 10% Flow –termination classically seen in PSV……..

  26. Flow Cycling Set PS level Identify mode….. PSV…… Patient Triggered, Flow Cycled, Pressure limited Mode Flow (L/m) Pressure (cm H2O) Volume (mL) Time (sec)

  27. Expiratory flow pattern…… E-time

  28. Normal Patient Air Trapping……… AUTO PEEP Inspiration Time Flow (L/min) Air-trapping AUTO PEEP Expiration When expiratory flow doesn’t return to base line………and inspiration starts before exp ends….

  29. Where we can find air-trapping…..? • Pressure wave: while performing an expiratory hold, the waveform rises above baseline. • Flow wave: the expiratory flow doesn’t return to baseline before the next breath begins. • Volume wave: the expiratory portion doesn’t return to baseline. • Flow/Volume Loop: the loop doesn’t meet at the baseline • Pressure/Volume Loop: the loop doesn’t meet at the baseline

  30. Measuring Auto -PEEP……….

  31. Auto-PEEP……. • Auto-PEEP = The averaged pressure by trapped gas in different lung units • A dynamic entity may not present in all breath • Short TE air entrapment • TEshorter than 3 expiratory time constant • So it is a potential cause of hyperinflation

  32. Response to Bronchodilator…. After Before Long TE Shorter TE Flow Time PEFR Improved PEFR To assess response to bronchodilator therapy,…. 1. An increase in peak expiratory flow rate. 2. The expiratory curve should return to baseline sooner. Where else it can be observed…..??

  33. 3 2 1 . V 1 2 3 Bronchodilator Response….. F-V loop AFTER Relief Bronchospasm Normal 3 3 2 2 1 1 . . V LPS VT V 1 1 2 2 3 3

  34. PRESSURE waveform……… Pressure mode PIP Insp Exp Pressure End Ex Pres PEEP Ti TE Time

  35. PRESSURE waveform……… To Increase Mean Airway Pressure…. 1. Increase flow 2. Increase peak pressure 3. Lengthen inspiratory time 4. Increase PEEP 5. Increase Rate MAP….. PIP     Pressure  PEEP Ti TE Time

  36. Identifying type of Breath/ mode of vent………….. Assisted Controlled Pressure Time

  37. Identify vent mode…. P Interpret the mode: Mode Pressure support/CPAP The pressure waveform has a plateau The flow waveform doesn't return to baseline Is it a Volume or Pressure mode? Is it a Control or Support mode?

  38. Identify vent mode…. Interpret the mode: Is it a Volume or Pressure mode? Is it a Control or Support mode?

  39. Flow (L/min) Pressure (cm H2O) Volume (ml) SIMV + PS + CPAP Pressure control ventilation Identify mode……? Set P level Set P level CPAP level Time (sec)

  40. Inspiratory Tidal Volume VOLUME waveform ………. Pressure controlled Expiration Inspiration Volume TI TE Time

  41. How does it help…….??? • Air Leaks • Setting appropriate I-time • Weaning • Active Exhalation

  42. Air Leak………… Volume (ml) Air Leak Time (sec) A = exhalation that does not return to zero

  43. Where to look……? Endotracheal Tube Leaks…… Volume waveform Pressure-volume loop Flow-volume loop

  44. Air Leak………… P-V loop Volume waveform…. V 30 VT ml P -10 F V F-V loop

  45. Setting Appropriate I-Time ………. ……to get desired VT PCV…. PIP= 20, Vt (achieved) = 15 15 cc volume 0 1 2 3 4 5 6 Time Flow 1 2 3 4 5 6 Time Short I – time ……low Vt

  46. Setting Appropriate I-Time ………. 15 cc 20 cc volume 0 1 2 3 4 5 6 Lost VT Flow 4 1 2 3 5 6 Time Appropriate I – time ……good Vt

  47. Volume waveform … trending..guides for weaning PCV… SIMV A….Ineffective tidal volume in spontaneous breaths; B….Improved tidal volume during spontaneous breaths.

  48. Active Exhalation…….. Volume (ml) Time (sec)

  49. The volume waveform is most commonly used to assess which two conditions? Answer: Air trapping and leaks

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