The document discusses newer modes of mechanical ventilation that were introduced to address clinical issues like poor patient-ventilator synchrony, prolonged weaning times, and ventilator-induced lung injury. It classifies the newer modes as dual modes that combine volume and pressure control, modes that adapt to lung characteristics, and knowledge-based weaning modes. It provides more details on proportional assist ventilation (PAV+), airway pressure release ventilation (APRV/BIPAP), and Smartcare—modes that aim to improve synchrony, maintain high functional residual capacity, and reduce workload for clinicians respectively.

1. Newer modes of Mechanical Ventilation Dr. T.R. Chandrashekar Director Critical Care K.R.Hospital Bangalore

2. Outline of the talk Which modes qualify as newer modes? Why newer modes were introduced ? Let us conceptualise the newer modes My classification of newer modes Do we require them? Evidence base A few important modes- I will discuss VAPS, PAV+, APRV/BIPAP, Smartcare

3. SIMV PCV ACV CMV Basic Modes? PS Newer [Alternative] Modes ? Volume support (VS) Volume Assured Pressure Support (VAPS) Pressure regulated volume control ventilation (PRVC) Mandatory minute ventilation (MMV) PROPORTIONAL ASSIST VENTILATION(PAV) ADAPTIVE SUPPORT VENTILATION(ASV) Smartcare/Automatic tube Compensation BIPAP/DUOPAP Airway pressure release ventilation (APRV ) High Frequency Ventilation/oscillation Partial Liquid Ventilation (Perflurocarbon) Neurally Adjusted Ventilatory Assist (NAVA) Fractal ventilation

4. What are Physicians Doing? 1,638 patients in 412 ICUs 47% Assist-Control Ventilation 46% Pressure Support and/or SIMV 7% Other Variability in modes across nations No variability in settings Esteban et al, AJRCCM 2000; 161:1450-8

5. Modes of Ventilation during Weaning Esteban et al, AJRCCM 2000;161:1450 PS SIMV + PS Intermittent SB trials Others SIMV Daily SB trials Number of ventilated patients, (%)

6. Why New Modes? Address important clinical issues: Poor trigger Proportional assist to match patients effort Improve patient - ventilator synchrony! More rapid weaning! Less likelihood of VILI Less hemodynamic compromise More effectively ventilate/oxygenate! Satisfies our craving for adventure - (engineers and clinicians) We like better numbers - (seduction by pulse oximetry)

7. Why newer modes were introduced ? Let us conceptualise the newer modes

8. Striving for better outcomes: The three • S pontaneous breathing (Girard 2008; MacIntyre 2000, Levine 2008) • S ynchrony (Chao 1997;Thille 2006; De Wit 2009) • S edation management (Kress 2000, Girard 2008, De Wit 2009) “S”s All reduce time on mechanical ventilation Nearly 50% time is spend on weaning

9. Phases of ventilatory cycle Delay, Missed breaths Fatigue/VIDD/runaway

10. Old modes trigger delay

11. Trigger in conventional modes We are targeting the last part of the cycle and Also add the delay from the Y piece or the machine end Trigger delay is inbuilt in the old modes

12. NAVA Esophagus

13. Sinderby et al, Nature Med 1999;5:1433 Time (s) 0 1 4 3 2 0 1 4 3 2 Airway Pressure Trigger Onset of diaphragmatic electrical activity Onset of ventilator flow Neural Trigger 0 20 -5.0 0.0 0.0 0.5 -1 0 1 Flow (l/s) Volume (l) P es (cm H 2 O) P aw (cm H 2 O ) Missed breaths

14. PAV+ vs. PCV /PSV example PCV 15 cmH2O PAV+ at 75% Compared to PCV, the PAV+ mode better matches patient’s effort to ventilator output. PAV+ P T P T P T P T P T P T Proportional support has synchronised inspiration to expiration cycling

15. These can lead to disuse atrophy of the respiratory muscles (VIDD) or lowering of the CO 2 set point. Either case can delay weaning and result in more ventilator days! or M Younes. Proportional Assist Ventilation, A New Approach to Ventilatory Support. Theory. Am Rev Respir Dis 1992;145:114-120. The practitioner’s typical response to an increase in demand is what? we need to select a level of pressure support that is “ not too low, not too high, but just right”. Proportional support to patients effort which can change from breath to breath is ideal Increase support Sedate

16. Proportional support is vital No Diaphragm activity Missed breaths Possibly to much pressure support which had suppressed the diaphragmatic activity Increase the PS

17. Automated mechanical ventilation is the future A growing number of medical errors in the literature related to Workload Due to the shortage of personnel High frequency of severe ‘burnout syndrome’ among physicians and nurses working in ICUs. High frequency of staff turnover

18. Automated mechanical ventilation is the future In the study by Donchin et al , Average number of activities per patient per day was 178 Activities related to breathing were the most frequent (26% of all activities) An estimated mean number of errors per patient per day was 1.7 Errors related to breathing were the second most frequent (23% of all errors), after errors related to data entry

19. The Future of Mechanical Ventilation Advanced closed-loop systems -Reduce the staff workload and to reduce the duration of MV What is a Closed Loop Ventilation ? Automated mechanical ventilation is the future

20. Closed Loop Ventilation Ventilator Patient Clinician Open Loop Ventilation Basic modes- PS/SIMV/CMV Set volume/presuure/flow Patient has to adapt to the ventilator Gets feedback on lung resistance/compliance Adapts to the patient- ASV/PAV+/NAVA Smartcare Intensivists brain

21. My classification of new MODES Dual modes Which combine Volume mode + Pressure modes- VS, MMV, VAPS, PRVC etc… Modes which adapt to lung characteristics ( Resistance & Compliance) PAV+, ASV Spontaneous breathing + higher FRC- APRV/ BIPAP Knowledge based Weaning modes- Smartcare, ATC, PAV, ASV, NAVA Better trigger mechanism- NAVA

22. Arguments Against New Modes Lack high-level evidence for better patient outcomes If we try a new mode and the patient has a good outcome, we say it was due to the new mode. But if try a new mode and there is a bad outcome, we say the patient was going to die anyway. Potential for harm (these are often not reported) Improved gas exchange does not necessarily improve outcomes: high tidal volume, iNO, prone New is not necessarily better Solution to a problem or in search of a problem?

23. Better oxygenation, faster weaning, lesser sedation, less Asynchrony YES- BUT mortality benefit not proved Dual modes most popular but no great evidence BIPAP no great evidence NAVA -emerging evidence even in children and NIV ASV- physiological mode –accumulating evidence (ARDS/COPD) PAV +-better than PAV, physiological mode –accumulating evidence, NIV good evidence Smartcar e-unique mode can say ventilator has intensivist’s brain-good evidence for weaning

24. I will discuss these modes Dual modes- VAPS – PAV+, BIPAP Smartcare VS/PRVC/MMR/MMV etc.. ASV /APRV / ATC/NAVA

25. DUAL MODES

26. Lung Compliance Changes and the P-V Loop Volume (mL) PIP levels Preset V T P aw (cm H 2 O) Volume Targeted Ventilation COMPLIANCE Increased Normal Decreased

27. Volume Control : good and bad Guaranteed tidal volume- even with variable compliance and resistance. Less atelectasis compared to pressure control. Can cause excessive airway pressure-VILI The limited flow available may not meet the patient’s desired inspiratory flow rate-asynchrony Leaks = Volume loss

28. Lung Compliance Changes and the P-V Loop Volume (mL) Preset PIP V T levels P aw (cm H 2 O) COMPLIANCE Increased Normal Decreased Pressure Targeted Ventilation

29. Pressure Control : good and bad • Limits excessive airway pressure • Improves gas distribution • Less VT as pulmonary mechanics change-atelectasis • Potentially excessive VT as compliance improves

30. 1.Set Tidal Volume With 2. Safer Pressure Limit Target

31. 60 -20 60 Flow L/min Volume Switch from Pressure control to Volume control L 0 0.6 40 VAPS-Volume assured Pressure Support Normal PS If Compliance decreases P aw cmH 2 0 Set tidal volume cycle threshold Set pressure limit Tidal volume met Tidal volume not met Flow cycle

32. Dual Modes Volume target achieved-can target a pressure limit Issues not addressed Trigger delay Proportional support-VIDD/fatigue Not taking into account lung mechanic’s resistance/compliance Not physiological -asynchrony

33. PAV +(Proportional Assist Ventilation) Provides pressure, flow assist, and volume assist in proportion to the patient’s spontaneous effort, the greater the patient’s effort, the higher the flow, volume, and pressure The operator sets the ventilator’s volume and flow assist at approximately 80% of patient’s elastance and resistance. The ventilator then generates proportional flow and volume assist to augment the patient’s own effort

34. PAV+ uses the compliance and resistance information collected every 4-10 breaths to know what it’s fighting against . PAV+ uses the flow and volume information collected every 5 milliseconds to know what the patient wants. PAV+ combines this data with the %Supp information input by the clinician to determine how much pressure to supply to the system. PAV+

35. The clinician will NOT set a rate, tidal volume, flow or target pressure. Instead, the clinician will simply set the percentage of work that the ventilator should do. f %Supp x x x x PAV+ V . V t P i

36. PAV+ Start patients at 70% and wean back to stabilize When disease process has sufficiently reversed, decrease %Support over 2 hr intervals

37. + PAV+ Potential Benefits 1. Comfort. 2. Lower peak airway pressure. 3. Less need for paralysis and/or sedation. 4. Less likelihood for over ventilation. 5. Preservation and enhancement of patient’s own control mechanisms such as metabolic ABG control and Hering-Breuer reflex. Some patients have a high rate normally, so a high rate on PAV + may or may not reflect distress; check other signs; Try increasing assist to see if rate goes down Don’t be surprised if RR climbs when switching from other modes

38. Circuit MUST be free of large leaks (small leaks are okay). No external nebulizers which add flow. PAV+ Limitations PAV+ is NOT recommended for… Low Respiratory drive Abnormal breathing pattern Extreme air trapping Large mechanical leaks.

39. APRV/BIPAP Maintain high FRC-better oxygenation Lung in safe zone-less de-recruitment /VILI Spontaneous breaths- diaphragm is active hence less VIDD/better Hemodynamics Less sedation and analgesia? Conflicting results APRV is IRV hence more impetus on Oxygenation/ synchrony problems persist BIPAP- less synchrony problems Keeps the lung in lung protective zone Keeps the lung in lung protective zone

40. APRV settings P aw T high (4-5) Sec T low P high P low ( 1 sec) Time-triggered, Time-cycled, Pressure-limited, Spontaneous breathing is allowed at any point during the ventilatory cycle FLOW P high -This parameter is set with the goal of improving oxygenation. P low -The setting of this parameter has the goal of facilitating ventilation or CO2 clearance. It is this inverse inspiratory:expiratory (I:E) ratio that distinguishes APRV from bi-level positive airway pressure (BiPAP=1:1)

41. BiLevel Ventilation: Uses 2 pressure levels for 2 time periods PEEP low & PEEP high , T high and T low Patient triggering & cycling can change phases If PS is set higher than PEEP H , the PS pressure is applied to a spontaneous effort at upper pressure If set PS < than Phigh then only applied in the lower pressure level If PS> than P-High,Then spontaneous breaths at both levels will be supported by PS P T Synchronized Transitions PEEP HIGH PEEP LOW T LOW T HIGH Synchronized Transitions PEEP High + PS P PEEP L PEEP H Pressure Support Spontaneous Breaths P Pressure Support T

42. Smartcare/NeoGanesh Complete Closed Loop

43. The “Zone of Respiratory Comfort” or “ZoRC” The 3 monitored parameters: • spontaneous breath rate, fspn • spontaneous tidal volume, VT • etCO2 “ ZoRC”-Goals: Regulate Pressure Support to stabilize the patient within their ZoRC 2) Reduce PS stepwise ( in steps of 2 to 4 cmsH2o ) to no support, keeping the patient within their ZoRC. 3) Conduct a Spontaneous Breathing Trial with no support; if patient remains within ZoRC, recommend separation from ventilator.

44. Smartcare These therapeutic measures are based on a clinical protocol that has been tested and verified during several years of development ..

45. SmartCare/PS the clinical evidence In February 2008, the FDA gave clearance for additional claims of efficacy SmartCare can Reduce overall ventilation time by 33% Decrease ICU length of stay by up to 20% Reduce weaning duration by up to 40%

46. New Modes of Mechanical Ventilation: Summary Older modes & ventilators: passive, operator-dependant tools New modes on new generation ventilators: adaptively interactive to patient goal oriented Low operator activity Adapted from John J. Marini, MD; AARC congress, 11/98

47. The Evidence for New Ventilator Modes … It’s not the ventilator mode that makes a difference … … It’s the skills of the clinician that makes the difference. Any ventilator mode has the potential to do harm! High level evidence is lacking that any new ventilator mode improves patient outcomes compared to existing lung-protective ventilation strategies. Dean Hess

48. Thank you Innovation and Automation is the future

50. PAV+ 80% with varying Demand Patient Work Machine Work

51. Amplification of Patient Effort • Small at low levels and high at high levels • 20% Support-1.25:1 • 50% Support -2:1ratio • 95% Support 20:1

52. Equation of Motion for the respiratory system Paw + Pmus = V’ x R +  V x E Ventilator output : Triggering, Cycling Control of flow, rise time and pressure Mechanical Patient response Chemical Reflex Behavioral

53. What is ASV? Goal 2: Three-knob ventilation T p Rate P sup P insp T i T e @ V t Conventional ASV FiO 2 PEEP CMV SIMV PCV PSV

54. How do I apply ASV? Ideal Body Weight Ideal Body Weight You % Minute Volume

55. How do I apply ASV? Ideal Body Weight Test breaths You % Minute Volume Automatically applies 3 test breaths to determine lung characteristics

56. ASV