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CPAP/PSV

CPAP/PSV. Objectives. Understand the difference between CPAP, PEEP and PSV Know the breath types with PSV: supported breaths Know the phase variables of the PSV: trigger, limit and cycle Understand the ETS cycling mechanisms: flow and time Setting the Level of Pressure Support

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CPAP/PSV

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  1. CPAP/PSV

  2. Objectives • Understand the difference between CPAP, PEEP and PSV • Know the breath types with PSV: supported breaths • Know the phase variables of the PSV: trigger, limit and cycle • Understand the ETS cycling mechanisms: flow and time • Setting the Level of Pressure Support • Adjustment of pressure support • Using PSV with different modes: SIMV • Using PSV for weaning • Advantages and disadvantages of PSV

  3. CPAP

  4. Continuous Positive Airway Pressure: CPAP • Ventilators can provide CPAP for spontaneously breathing patients • Helpful for improving oxygenation in patients with refractory hypoxemia and a low FRC • CPAP setting is adjusted to provide the best oxygenation with the lowest positive pressure and the lowest FiO2

  5. Spontaneous Breath

  6. Spontaneous Breathing Pressure (cm H2O) Flow (L/m) Volume (mL) Time (sec)

  7. Continuous Positive Airway Pressure (CPAP) Pressure (cm H2O) CPAP Level Flow (L/m) Volume (mL) Time (sec)

  8. CPAP

  9. CPAP

  10. CPAP

  11. CPAP

  12. PEEP

  13. PEEP: Positive End Expiratory Pressure • The term PEEP is defined as positive pressure at the end of exhalation during either spontaneous breathing or mechanical ventilation. However, use of the term commonly implies that the patient is also receiving mandatory breaths from a ventilator. • PEEP becomes the baseline variable during mechanical ventilation

  14. PEEP • Helps prevent early airway closure and alveolar collapse and the end of expiration by increasing (and normalizing) the functional residual capacity (FRC) of the lungs • Facilitates better oxygenation NOTE: PEEP is intended to improve oxygenation, not to provide ventilation, which is the movement of air into the lungs followed by exhalation

  15. Pressure Support Ventilation Phase Variables, Breath Type and Sequence

  16. Pressure Support Ventilation: PSV • Patient triggered, pressure targeted, flow cycled mode of ventilation • Requires a patient with a consistent spontaneous respiratory pattern • The ventilator provides a constant pressure during inspiration once it senses that the patient has made an inspiratory effort

  17. Patient Trigger

  18. Pressure Limit

  19. Flow Cycled

  20. Flow Cycling During PSV • Flow cycling occurs when the ventilator detects a decreasing flow, which represents the end of inspiration • This point is a percentage of peak flow measured during inspiration • PB 7200 – 5 L/min • Bear 1000 – 25% of peak flow • Servo 300 – 5% of peak flow • No single flow-cycle percent is right for all patients

  21. Flow Cycling During PSV • Effect of changes in termination flow • A: Low percentage (17%) • B: High percentage (57%) • Newer ventilators have an adjustable flow cycle criterion, which can range from 1% - 80%, depending on the ventilator

  22. PSV: Time Cycling • NOTE: During pressure support ventilation (PSV), inspiration ends if the inspiratory time (TI) exceeds a certain value. This most often occurs with a leak in the circuit. For example, a deflated cuff causes a large leak. The flow through the circuit might never drop to the flow cycle criterion required by the ventilator. Therefore, inspiratory flow, if not stopped would continue indefinitely. For this reason, all ventilators that provide pressure support also have a maximum inspiratory time.

  23. Supported Breaths

  24. Pressure Support Ventilation The Mode

  25. Triggered Modes of VentilationPressure Support Ventilation Patient Triggered, Pressure Limited, Flow Cycled Ventilation

  26. PSV

  27. PSV

  28. Pressure Support Ventilation(PSV) Set PS Level Pressure (cm H2O) Flow Cycling Better Efforts Longer Inspiration Flow (L/m) Volume (mL) Time (sec) Patient Triggered, Flow Cycled, Pressure limited Mode

  29. CPAP+PSV Set PS Level Pressure (cm H2O) CPAP Level Flow Cycling Flow (L/m) Volume (mL) Time (sec) Patient Triggered, Flow Cycled, Pressure limited Mode

  30. Pressure Support Ventilation Settings and Adjustment

  31. Setting the Level of Pressure Support • Goal: To provide ventilatory support • Spontaneous tidal volume is 10 – 12 mL/Kg of ideal body weight • Maintain spontaneous respiratory rate <25/min • Goal: To overcome system resistance (ET Tube, circuit, etc.) in the spontaneous or IMV/SIMV mode • Set pressure at (PIP – Pplateau) achieved in a volume breath or at 5 – 10 cm H2O

  32. Setting the Level of Pressure Support • Exercise: Using the PIP and thePPlateau from the pressure waveform below, recommend a pressure support setting for this patient (patient is in VC-SIMV mode) 35 25 Answer: 10 cm H2O

  33. The Results of Your Work 35 cm H2O 10 cm H2O

  34. PS=6, VT= 350

  35. PS=10, VT= 600

  36. Pressure Support Ventilation Indications, Advantages and Disadvantages

  37. Pressure Support Ventilation: Indications • Spontaneously breathing patients who require additional ventilatory support to help overcome • WOB, CL, Raw • Respiratory muscle weakness • Weaning (either by itself or in combination with SIMV)

  38. Pressure Support Ventilation: Advantages • Full to partial ventilatory support • Augments the patients spontaneous VT • Decreases the patient’s spontaneous respiratory rate • Decreases patient WOB by overcoming the resistance of the artificial airway, vent circuit and demand valves • Allows patient control of TI, I, f and VT

  39. Pressure Or Volume-Targeted Ventilation Advantages Disadvantages Requires consistent spontaneous ventilation Patients in stand-alone mode should have back-up ventilation VT variable and dependant on lung characteristics and synchrony Low exhaled VE Fatigue and tachypnea if PS level is set too low • Full to partial ventilatory support • Augments the patients spontaneous VT • Decreases the patient’s spontaneous respiratory rate • Decreases patient WOB by overcoming the resistance of the artificial airway, vent circuit and demand valves • Allows patient control of TI, Vm , f and VT • Set peak pressure • Prevents respiratory muscle atrophy • Facilitates weaning • Improves patient comfort and reduces need for sedation • May be applied in any mode that allows spontaneous breathing, e.g., VC-SIMV, PC-SIMV

  40. PS with Other Modes SIMV

  41. VC-SIMV: +Efforts

  42. VC-SIMV/PSupp

  43. PCV+PSupp

  44. Thank You

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