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Ventilator graphics

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Prithvi Raj S J
Prithvi Raj S J

1) Ventilator graphics display waveforms that facilitate assessment of a patient's condition on mechanical ventilation. The most commonly used graphics are scalars (flow vs time, pressure vs time, volume vs time) and loops (pressure-volume, flow-volume). 2) Scalar graphics show the relationship between flow, volume, or pressure over time. Loops show the relationship between pressure and volume or flow and volume. These graphics provide information about ventilator settings, lung mechanics, and the identification of common issues like airway obstruction or air trapping. 3) Proper analysis of ventilator graphics is essential for optimizing ventilator settings and recognizing abnormalities that may require intervention to improve a patient's ventilation

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Ventilator Graphics Prithviraj S J
Concepts • Is an Essential tool in managing patients on Mechanical ventilators. • All Latest Mechanical Ventilators are equipped with graphics that display selected ventilator waveforms facilitating assessment of the patient’s condition. • Graphics displayed are two types 1. Scalars 2. Loops
• Most commonly used ventilator graphics are 1. Scalars • Flow vs Time • Pressure vs Time • Volume vs Time 2. Loops • Pressure – Volume Loop • Flow – Volume Loop
Scalar Graphics • 3 components that make up the ventilator graphics flow, Volume and Pressure are plotted against Time • X axis is Time • Y axis is pressure, volume and flow. • Typically its Flow vs Time, Pressure vs Time and Volume vs Time ,
Analysis of Scalar Graphics • Basics of Flow vs Time Curve 1. Spontaneous Breath 2. Mechanical Breath
Flow Patterns • Insp Flow Pattern Square, indicating constant flow delivery – Selected by operator • Below Baseline – Expiratory Flow which is dependent on the patient’s lung characteristics and effort • Only flow vs Time curve demonstrates tracing below baseline. • Except Pressure vs Time Curve where a small deflation occurs below the baseline when the patient initiates inspiration.
Components of Inspiratory Flow • Initiation of Flow at the beginning of inspiration • Peak Inspiratory Flow • End of Insp flow delivery and beginning of expiration • Inspiratory time • Expiratory Time • Total Cycle Time
Components of Expiratory Flow Expiration is a passive process whether its mechanical or spontaneous . • Initiation of expiration • Peak Expiratory Flow Rate • Duration of expiratory flow • Expiratory Time
Recognition of common abnormalities • Airway Obstruction vs Active Exhalation • Response of Bronchodilators.
Air Trapping or Auto Peep • Presence of Air Trapping may result from 1. Inadequate Expiratory Time 2. Too high Respiratory Rate 3. Long Inspiratory Time 4. Prolonged Exhalation due to bronchoconstriction Higher Inspiratory flow rate (In Volume Cycled) or Shorted Ti ( In Time Cycled Ventilators ) allow for Longer TE and may eliminate auto PEEP
Basics of Volume vs Time • Information obtained from Volume vs Time Scalar graph includes • Inspiratory Tidal Volume • Inspiratory Phase • Expiratory Phase • Inspiratory Time
Recognition of Common Abnormalities • Air Leaking – Leak in the circuit or around tracheal tube. The expiratory tracing smoothly and doesn’t reach baseline. Volume of leak can be easily estimated by measuring the distance from the plateau to end of expiratory tracing. • Active Exhalation – Forces Exhalation is seen as tracing extends below zero line. It can occur if the flow transducer is out of calibration.
Basics of Pressure Vs Time Curve Spontaneous Breath - Inspiration below the baseline and expiration above .
Mechanical Breath Most useful waveform and Visual Representations of • PIP – Maximum Pressure achieved during a breath. Increased airway resistance Paw or decreased lung compliance results in increased PIP. • PEEP - its confirmed only on Pressure Time and Pressure volume loop, PEEP is present when baseline pressure is above Zero.
Assisted Vs Controlled Breath • Pressure vs Time scalar verifies the triggering mechanism of the breath. • If breaths are initiated at baseline at fixed intervals , the mode is time triggered or control mode , • In Assist mode , patient initiates the breath by generating the negative pressure, sensor recognizes the patient’s effort and delivers the mechanical breath
Components of Inflation Pressure • Plateau Pressure / Alveolar Pressure- • Transairway pressure PTA = PIP – P Plat
Recognition of common Abnormalities • Normal curve • High Raw – Increase in the PTA is associated with airway resistance . • High Flow – Insp Time is shorter than normal indicating a higher Insp gas flow rate. • Decreased Lung compliance – Increase in plateau pressure and corresponding increase in PIP is consistent with decreased lung compliance.
Inadequate Flow • Pressure Vs Time can also detect inadequate flow that is indicated when the pressure rises slowly or sometimes is indicated when there is a depression in inspiratory limb of the pressure control.
Loops Graphics • Pressure Volume Loop • Flow Volume Loop
Pressure -Volume Loops - Type of Breath
Components of Pressure Volume loops • Beginning point on p-V loop is the FRC level. When PEEP added , FRC increases. • Pressure Volume loop traces changes in pressure and corresponding volumes in changes in volume. • Insp begins from the FRC Level and terminates when preset parameter ( Volume and Pressure) is achieved. • Tracing continues during expiration and returns FRC at the end of exhalation. • PIP and delivered tidal volume can be obtained from PV Loop
PEEP
Inflection Points • It’s a point of change in the slope of line. It represents the sudden change in alveolar opening and closing. • Lower Inflection points – Opening pressure • Higher Inflection points – recoiling characteristics. • Higher the opening pressure , the stiffer the lung. • Setting PEEP levels at the level of the lower inflection points is recommended to optimize alveolar recruitment and prevent repeated opening and closing of alveoli.
Work of Breathing • Advantage of PV loop is that it provides a quick assessment of elastic as well as resistive work of breathing. • WOB = Pressure * Volume
Recognition of common abnormalities • Decreased lung compliance Right shift is Decreased and left shift is Increased • Volume targeted ventilation PIP is Variable and Vt is Preset
• Pressure Targeted Ventilation PIP is constant and Vt is changing variable • Increased airway resistance/ Hysteresis Increased airway resistance is associated with the abnormal widening of the inspiratory tracing Eg- Obstructive disorder patients
• Alveolar Overdistension It common in ARDS patient in Volume Targeted Mode. Classic Sign Known as Beak effect / Duckbill shows increase in airway pressure w/o any appreciable increase in volume. Switch to Pressure Targeted at appropriate pressure or reduction in volume are indicated. • Increased WOB Inadequate sensitivity setting promotes increased WOB.
Inadequate Inspiratory Flow • Inappropriate Inspiratory flow rates are recognized from a scooped-out pattern. • In some situations, the patient makes inspiratory effort in the middle of the mechanical breath exhibiting “notch” on the inspiratory curve.
Air Leak Expiratory Curve doesn’t reach to zero , an air leak is present
Flow – Volume Loop
Recognition of common abnormalities • Air Leak • Auto Peep / Air trapping
• Increased Airway Resistance • Airway Secretions / Accumulation of condensate
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Ventilator graphics

  • 2. Concepts • Is an Essential tool in managing patients on Mechanical ventilators. • All Latest Mechanical Ventilators are equipped with graphics that display selected ventilator waveforms facilitating assessment of the patient’s condition. • Graphics displayed are two types 1. Scalars 2. Loops
  • 3. • Most commonly used ventilator graphics are 1. Scalars • Flow vs Time • Pressure vs Time • Volume vs Time 2. Loops • Pressure – Volume Loop • Flow – Volume Loop
  • 4. Scalar Graphics • 3 components that make up the ventilator graphics flow, Volume and Pressure are plotted against Time • X axis is Time • Y axis is pressure, volume and flow. • Typically its Flow vs Time, Pressure vs Time and Volume vs Time ,
  • 5. Analysis of Scalar Graphics • Basics of Flow vs Time Curve 1. Spontaneous Breath 2. Mechanical Breath
  • 6. Flow Patterns • Insp Flow Pattern Square, indicating constant flow delivery – Selected by operator • Below Baseline – Expiratory Flow which is dependent on the patient’s lung characteristics and effort • Only flow vs Time curve demonstrates tracing below baseline. • Except Pressure vs Time Curve where a small deflation occurs below the baseline when the patient initiates inspiration.
  • 7. Components of Inspiratory Flow • Initiation of Flow at the beginning of inspiration • Peak Inspiratory Flow • End of Insp flow delivery and beginning of expiration • Inspiratory time • Expiratory Time • Total Cycle Time
  • 8. Components of Expiratory Flow Expiration is a passive process whether its mechanical or spontaneous . • Initiation of expiration • Peak Expiratory Flow Rate • Duration of expiratory flow • Expiratory Time
  • 9. Recognition of common abnormalities • Airway Obstruction vs Active Exhalation • Response of Bronchodilators.
  • 10. Air Trapping or Auto Peep • Presence of Air Trapping may result from 1. Inadequate Expiratory Time 2. Too high Respiratory Rate 3. Long Inspiratory Time 4. Prolonged Exhalation due to bronchoconstriction Higher Inspiratory flow rate (In Volume Cycled) or Shorted Ti ( In Time Cycled Ventilators ) allow for Longer TE and may eliminate auto PEEP
  • 11. Basics of Volume vs Time • Information obtained from Volume vs Time Scalar graph includes • Inspiratory Tidal Volume • Inspiratory Phase • Expiratory Phase • Inspiratory Time
  • 12. Recognition of Common Abnormalities • Air Leaking – Leak in the circuit or around tracheal tube. The expiratory tracing smoothly and doesn’t reach baseline. Volume of leak can be easily estimated by measuring the distance from the plateau to end of expiratory tracing. • Active Exhalation – Forces Exhalation is seen as tracing extends below zero line. It can occur if the flow transducer is out of calibration.
  • 13. Basics of Pressure Vs Time Curve Spontaneous Breath - Inspiration below the baseline and expiration above .
  • 14. Mechanical Breath Most useful waveform and Visual Representations of • PIP – Maximum Pressure achieved during a breath. Increased airway resistance Paw or decreased lung compliance results in increased PIP. • PEEP - its confirmed only on Pressure Time and Pressure volume loop, PEEP is present when baseline pressure is above Zero.
  • 15. Assisted Vs Controlled Breath • Pressure vs Time scalar verifies the triggering mechanism of the breath. • If breaths are initiated at baseline at fixed intervals , the mode is time triggered or control mode , • In Assist mode , patient initiates the breath by generating the negative pressure, sensor recognizes the patient’s effort and delivers the mechanical breath
  • 16. Components of Inflation Pressure • Plateau Pressure / Alveolar Pressure- • Transairway pressure PTA = PIP – P Plat
  • 17. Recognition of common Abnormalities • Normal curve • High Raw – Increase in the PTA is associated with airway resistance . • High Flow – Insp Time is shorter than normal indicating a higher Insp gas flow rate. • Decreased Lung compliance – Increase in plateau pressure and corresponding increase in PIP is consistent with decreased lung compliance.
  • 18. Inadequate Flow • Pressure Vs Time can also detect inadequate flow that is indicated when the pressure rises slowly or sometimes is indicated when there is a depression in inspiratory limb of the pressure control.
  • 19. Loops Graphics • Pressure Volume Loop • Flow Volume Loop
  • 20. Pressure -Volume Loops - Type of Breath
  • 21. Components of Pressure Volume loops • Beginning point on p-V loop is the FRC level. When PEEP added , FRC increases. • Pressure Volume loop traces changes in pressure and corresponding volumes in changes in volume. • Insp begins from the FRC Level and terminates when preset parameter ( Volume and Pressure) is achieved. • Tracing continues during expiration and returns FRC at the end of exhalation. • PIP and delivered tidal volume can be obtained from PV Loop
  • 22. PEEP
  • 23. Inflection Points • It’s a point of change in the slope of line. It represents the sudden change in alveolar opening and closing. • Lower Inflection points – Opening pressure • Higher Inflection points – recoiling characteristics. • Higher the opening pressure , the stiffer the lung. • Setting PEEP levels at the level of the lower inflection points is recommended to optimize alveolar recruitment and prevent repeated opening and closing of alveoli.
  • 24. Work of Breathing • Advantage of PV loop is that it provides a quick assessment of elastic as well as resistive work of breathing. • WOB = Pressure * Volume
  • 25. Recognition of common abnormalities • Decreased lung compliance Right shift is Decreased and left shift is Increased • Volume targeted ventilation PIP is Variable and Vt is Preset
  • 26. • Pressure Targeted Ventilation PIP is constant and Vt is changing variable • Increased airway resistance/ Hysteresis Increased airway resistance is associated with the abnormal widening of the inspiratory tracing Eg- Obstructive disorder patients
  • 27. • Alveolar Overdistension It common in ARDS patient in Volume Targeted Mode. Classic Sign Known as Beak effect / Duckbill shows increase in airway pressure w/o any appreciable increase in volume. Switch to Pressure Targeted at appropriate pressure or reduction in volume are indicated. • Increased WOB Inadequate sensitivity setting promotes increased WOB.
  • 28. Inadequate Inspiratory Flow • Inappropriate Inspiratory flow rates are recognized from a scooped-out pattern. • In some situations, the patient makes inspiratory effort in the middle of the mechanical breath exhibiting “notch” on the inspiratory curve.
  • 29. Air Leak Expiratory Curve doesn’t reach to zero , an air leak is present
  • 31. Recognition of common abnormalities • Air Leak • Auto Peep / Air trapping
  • 32. • Increased Airway Resistance • Airway Secretions / Accumulation of condensate