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Mode of ventilation
This document discusses respiratory failure and various modes of mechanical ventilation. It begins by distinguishing between respiratory failure and respiratory insufficiency. It then covers initiating mechanical ventilation using either volume ventilation or pressure ventilation. Various modes are discussed including volume-targeted modes like control, assist, SIMV+PS. Pressure-targeted modes like pressure control ventilation and PSV are also covered. The document discusses the challenges of ventilating ARDS patients and how newer dual modes and closed-loop modes can help minimize ventilator-induced lung injury while maintaining lung recruitment and pressures. It also introduces APRV and bi-level ventilation as newer modes to apply PEEP above the lower inflection point.
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Mode of ventilation
- 1. Respiratory Failure VVs.s. RespiratoryRespiratory InsufficiencyInsufficiency Associated withAssociatedwith •Abnormal ABGs •Immediate action is required •Clinical signs may not be very obvious Associated withAssociated with •Normal or near normal ABGs •Increased work of breathing •Accompanied by dyspnea, paradoxical breathing, use of accessory muscles
- 2. Initiation of MechanicalVentilation Volume Ventilation Pressure Ventilation
- 3.
- 4. VOLUME TARGETED VENTILATION DeliveredTidal Volume is ConstantDelivered Tidal Volume is Constant Better Control on PaCOBetter Control on PaCO22
- 5. Mode Selection ● ControlMode ● Assist Mode ● PEEP ● CPAP
- 6. PEEP and CPAP ●PEEP (Positive End Expiratory Pressure) - Mechanical CPAP ● CPAP (Continuous Positive Airway Pressure) – Spontaneous PEEP
- 7. Controlled Mode (Volume- TargetedVentilation) Preset VT Volume Cycling Dependent on CL & Raw Time (sec) Flow L/m Pressure cm H2O Volume mL Preset Peak Flow Time triggered, Flow limited, Volume cycled Ventilation
- 8. Assisted Mode (Volume-Targeted Ventilation) Time(sec) Flow L/m Pressure cm H2O Volume mL Preset VT Volume Cycling Patient triggered, Flow limited, Volume cycled Ventilation From: Essentials of Ventilator Graphics- An interactive CD. Vijay Deshpande, MS, RRT and Ruben Restrepo, MD, RRT. Available at www.respiratorybooks.com
- 9. Setting Trigger Sensitivity Pressure Inappropriatesensitivity setting
- 10. Pressure triggering imposeswork on the respiratory system that in some cases is excessive. Triggering work of breathing needs to be decreased. ADVANCEMENT: Introduction of Flow Triggering
- 11.
- 12. Flow Triggering Flow SensorFlow Sensor
- 13. On initiating abreath the patient receives all mechanical breaths of set tidal volume causing respiratory alkalosis. ADVANCEMENT: IMV and SIMV
- 14.
- 15. Patients are experiencingincreased work of breathing during spontaneous breaths through the tracheal tube in SIMV. ADVANCEMENT: Pressure Support Ventilation
- 16. SIMVSIMV (Volume-Targeted Ventilation)(Volume-Targeted Ventilation) SpontaneousBreaths Flow L/m Pressure cm H2O Volume mL
- 17. Unsupported Breathing througha Tracheal Tube
- 18. Pressure dropshows imposedPressure drop shows imposed work across ET-Tube whenwork across ET-Tube when flow is presentflow is present What TheWhat The CarinaCarina SeesSees Circuit Pressure Lower Carina Pressure Paw
- 19. Pressure Flow Volume (L/min) (cm H2O) (ml) SIMV +PS (Pressure-Targeted Ventilation) PS Breath Set PS level Set PC levelSet PC level Time (sec)Time (sec) Time-CycledTime-Cycled Flow-Cycled
- 20. How much PressureSupport?
- 21. Components of Inflation Pressure BeginExpiration Paw(cmH2O) Time (sec) Begin Inspiration PIPPIP Pplateau (Palveolar) Transairway Pressure (PTA) }} Exhalation Valve Opens ExpirationExpiration Inspiratory Pause
- 22. Initial Pressure SupportLevelInitial Pressure Support Level PSV level = PIP - PPlateau
- 23. Pressure Support Ventilation (PSV ) Strictly an assist form of mechanical ventilation Augments spontaneous tidal volume with a preselected level of positive inspiratory pressure Overcomes imposed work of breathing due to : Artificial Airways Demand valve system Ventilator circuitry Classified as a Pressure-limited, flow-cycled, assisted ventilation
- 24. PSV Time (sec) Flow Cycling SetPS level Flow L/m Pressure cm H2O Volume mL
- 25. Acute Lung Injury(ALI), Acute Respiratory Distress Syndrome (ARDS) and Volume Ventilation
- 26. Dilemma in VentilatoryManagement of ARDS Objective: Reopen collapsed and recruitable alveoli Strategy: Application of Positive Pressure Ventilation Commonly used Mode of Ventilation: Volume Targeted Problem: Alveolar Overdistention
- 27. Acute Lung Injury( ALI ) Damage to the Lung :Damage to the Lung : Not distributed homogeneouslyNot distributed homogeneously Even in severe cases ~ 1/3 lung is openEven in severe cases ~ 1/3 lung is open Open lung receives the entire tidalOpen lung receives the entire tidal volume resulting in :volume resulting in : OverdistensionOverdistension Local hyperventilationLocal hyperventilation Inhibition of surfactantsInhibition of surfactants Ravenscraft, Sue. Respiratory Care, Vol 41, No 2 : 105-111, Feb 1996
- 28. ALI and ARDS Non-HomogeneousLung Units Collapsed Recruitable Normal Lung Units
- 29. ALI and ARDS Effectof Volume Ventilation Set VT Collapsed Recruitable Normal Lung Units
- 30. Overdistension Volume(ml) Pressure (cm H2O) Littleor no change in VT Little or no change in VT Paw rises Paw rises Normal Abnormal Fig 8.10
- 31. VOLUME TARGETED VENTILATION DeliveredTidal Volume is ConstantDelivered Tidal Volume is Constant Better Control on PaCOBetter Control on PaCO22 Higher risk of Ventilator-induced Lung InjuryHigher risk of Ventilator-induced Lung Injury PPalvalv may Increasemay Increase Potential for local Alveolar Over-distentionPotential for local Alveolar Over-distention May promote patient-ventilator dyssynchronyMay promote patient-ventilator dyssynchrony and increased WOBand increased WOB
- 32. ARDS network. N EngJ Med 2000, 342(18):1301-1308. Multi-center NIH study demonstrated that ALI/ARDS patients ventilated with tidal volumes of 6 ml/Kg were significantly more likely to survive than those ventilated with tidal volumes of 12 ml/Kg.
- 33. Over-distention Observed on aPressure-Volume LoopObserved on a Pressure-Volume Loop Indicates hyperinflation or excessiveIndicates hyperinflation or excessive application of pressureapplication of pressure May promote BarotraumaMay promote Barotrauma Corrective action includes reduction in theCorrective action includes reduction in the Peak Inspiratory Pressure or Tidal VolumePeak Inspiratory Pressure or Tidal Volume
- 34. Ventilator-induced Lung Injury Occursas a result of: ■ Over-distention of alveoli ■ Repetitive opening and closure of lung units throughout the respiratory cycle
- 35. In ALI andARDS, Volume Ventilation seems to be detrimental ADVANCEMENT: Pressure Targeted Ventilation
- 36. ALI and ARDS Non-HomogeneousLung Units Collapsed Recruitable Normal Lung Units Pre set Pressure
- 37. PRESSURE TARGETED VENTILATION PIP and PPIP and Palvalv are Limitedare Limited Prevents Alveolar Over-distentionPrevents Alveolar Over-distention Provides better Patient-VentilatorProvides better Patient-Ventilator synchronysynchrony Delivered Tidal Volume depends onDelivered Tidal Volume depends on Airway Resistance and Lung ComplianceAirway Resistance and Lung Compliance Tidal Volume and PaCOTidal Volume and PaCO22 are variableare variable
- 38.
- 39. Assisted Mode (Pressure-Targeted Ventilation) Pressure Flow Volume (L/min) (cmH2O) (ml) Set PC level Time (sec)Time (sec) Time-Cycled Patient Triggered, Pressure Limited, Time Cycled Ventilation
- 40. Assisted Mode (Volume-Targeted Ventilation) AssistedMode (Volume-Targeted Ventilation) Time (sec)Time (sec) Flow L/m Pressure cm H2O Volume mL Preset VT Volume Cycling Patient triggered, Flow limited, Volume cycled Ventilation Assisted Mode (Pressure-Targeted Ventilation) Assisted Mode (Pressure-Targeted Ventilation) Pressure Flow Volume (L/min) (cm H2O) (ml) Set PC level Time (sec)Time (sec) Time-Cycled Patient Triggered, Pressure Limited, Time Cycled Ventilation Scalars in Assisted Mode FIGURE 1
- 41.
- 42.
- 43. ARDSnet Findings Lower TidalVolumes Use of rapid rates avoiding auto-PEEP ( < 35/min ) PPLAT < 30 cm H2O reduces mortality Lower PPLAT showed better outcome ARDSnet: 6ml/kg reduces mortality vs. 12 ml/kg
- 44. Strategies to VentilateALI and ARDS patients Prevent Alveolar Over-distention Use of low Tidal Volumes (5-7 ml/Kg) May promote de-recruitment of alveoli Prevent repetitive alveolar opening and closure Use of Recruitment Maneuver sustained increase in airway pressure application of adequate end-expiratory pressure (PEEP/CPAP)
- 45. Efforts made toprevent de-recruitment Application of PEEP Use of Inverse Ratio Ventilation with PEEP Use of Airway Pressure Release Ventilation (APRV) or BiLevel Ventilation
- 46. Saura P, BlanchL. How to set Positive End-Expiratory Pressure. Respir Care 2002; 47 (3): 279-295 Overdistention and repetitive opening and closing of alveolar units seem to contribute to progressive lung injury.
- 47. We want tomaintain spontaneous breathing, protect the lungs from high alveolar pressures and deliver the set Tidal Volume. ADVANCEMENT: Dual Ventilation with closed Looping
- 48. Initiation of MechanicalVentilation Volume Ventilation Pressure Ventilation Dual Ventilation
- 49. COMBINED PRESSURE/VOLUME VENTILATION Exploit beneficialeffects of bothExploit beneficial effects of both Pressure and Volume VentilationPressure and Volume Ventilation Improve Patient-ventilator SynchronyImprove Patient-ventilator Synchrony Prevent ventilator induced lung injuryPrevent ventilator induced lung injury
- 51. Closed-loop Ventilation Volume AssuredPressure Support Ventilation (VAPS) Pressure Augmentation ( PAug ) Volume Support ( VS ) Pressure Regulated Volume Control ( PRVC, Autoflow, VC+ ) Adaptive Support Ventilation ( ASV ) Proportional Assist Ventilation ( PAV )
- 52. PRVC Trigger On Exhaled VT< Set VT Exhaled VT > Set VT Pressure Support level increases stepwise until Exhaled VT = Set VT Pressure Support level decreases stepwise until Exhaled VT = Set VT
- 53. To recruit alveoli,mean airway pressure needs to be increased without causing Overdistension. ADVANCEMENT: Newer modes APRV and BiLevel
- 54. Amato MB., etal., Effect of a protective-ventilation strategy on mortality in ARDS. N Eng J Med 1998;338(6):347-354 Initial recruitment of alveolar units may be achieved by applying PEEP at a level above the lower inflection point of the P-V curve.
- 55. Volume(ml) PEEP > 2-3cm H2O above LIP Lung Protective Strategy Pressure
- 56. Inflection Points Lower Inflection Point(LIP or Pflex) Upper Inflection Point Volume Pressure
- 57. Airaway Pressure ReleaseVentilation (APRV)
- 58. Upper And LowerInflection Points 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O VT Alveolar collapse P T Lower inflection points are thought to be a point of critical opening pressure
- 59. Upper And LowerInflection Points 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O VT Alveolar overdisention Alveolar collapse P T
- 63. Possible Approaches toVentilate ARDS Patients APRV PCIRV BiLevel or BiVent PRVC HFO No data to indicate that any mode of ventilation is BETTER than conventional Pressure-A/C ventilation
- 64. Advances in MechanicalVentilation Control, Assist, PEEP, CPAP IMV, SIMV, PSV, PCV, Combinations of Volume or Pressure ventilation: SIMV +PSV, SIMV+PSV+CPAP VENTILATOR GRAPHICS CLOSED-LOOP VENTILATION VAPS, Paug VS, PRVC, ASV, , PAV, APRV, Fig 7.4
- 65.
- 67.
- 68. PSV Flow-Cycle Criteria Flow T PeakInspiratory Flow 5% 20% 40%
- 69.