Advanced modes-Do we need them?

Advanced Modes ofMechanical Ventilation : 

Advanced Modes ofMechanical Ventilation Dr. T.R. Chandrashekar Intensivist K.R.Hospital Bangalore

Issues : 

Issues One hour lecture Pre-lunch session Last lecture of the workshop Not much hands on experience for many of us How to make it interesting ? I divided my lecture in to two parts Why do we require them? And a few new modes

Outline of the talk : 

Outline of the talk Which modes qualify as newer modes? Why do we require newer modes? Let us conceptualize the newer modes My classification of newer modes Evidence base ? A few important modes- I will discuss VAPS,APRV/BIPAP, PAV+, Smartcare,

The Engineering Problem : 

The Engineering Problem The lung cannot expand itself, it can only move passively in response to external pressures Two ways to get air into the lung Create a negative pressure within the lung as occurs in free breathing humans Create a positive pressure at the airway opening to push air into the lung-PPV Inspiration Mechanical Breath Spontaneous Breath Pressure Time

Slide 5: 

Synchronised Intermittent Mandatory Ventilation Pressure Controlled Ventilation/Assist Volume controlled ventilation/Assist Basic Modes? Pressure Support Ventilation PS BASIC Modes SIMV VC AVC PC

Advanced/Newer/ Closed loop modes : 

Advanced/Newer/ Closed loop modes Mandatory minute ventilation (MMV)/MRV Volume support (VS)/Volume Assured Pressure Support (VAPS) Pressure regulated volume control ventilation (PRVC) Proportional Assist Ventilation(PAV+/PPS) Adaptive SupportVentilation (ASV) Neutrally Adjusted Ventilatory Assist (NAVA) BIPAP/DUOPAP/Airway pressure release ventilation (APRV ) Smartcare/Automatic tube Compensation(ATC) High Frequency Ventilation/oscillation Partial Liquid Ventilation (Perflurocarbon) Fractal ventilation

Slide 7: 

Smartcare ASV NAVA PAV PPS Advanced/ Closed loop ventilation APRV/BIPAP DUOPAP Advanced Modes that are going to stay in practice…..

Slide 8: 

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

Slide 9: 

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, (%)

Slide 10: 

Why newer modes were introduced ? Let us understand how they are different from the conventional modes

The goal of mechanical ventilation : 

The goal of mechanical ventilation In the acute setting is to ‘‘buy time’’ to give a patient a chance to recover from some catastrophe. The ideal ventilator would not damage Respiratory muscles Lung parenchyma

Slide 12: 

Goals of ventilation Setting the Ventilator Ventilator-Induced Lung Injury Lung protective ventilation Gas Exchange PaO2/PaCo2 Accepting hypoxia and hypercarbia Due to low volume ventilation Patient Comfort Synchrony sedation /paralysis Early weaning Hemodynamics

Slide 13: 

Patient effort Ventilator assistance . Kondili et al, Br J Anesthesia 2003;91:106 Resistive load Elastic load . Pmus Paw Resistance x flow Compliance x volume + + = Equation of motion for Mechanical Ventilation Controlled ventilation Pt/vent work shared-interaction

Advanced modes : 

Advanced modes Are useful only if (Pmus ) patients effort is involved Are useful once weaning is initiated Modes of Ventilation Conventional modes (Open loop ventilation) Closed loop Ventilation Advanced Closed loop Ventilation

Conventional Modes( Open loop) : 

Conventional Modes( Open loop) Basic modes-CMV/SIMV/PS Clinician Ventilator Patient Once parameters are set there is no sharing of information between the ventilator and the patient same settings are delivered each breath unless the clinician wants to change the settings Patient has to adapt to the ventilator

Advanced modes- Closed Loop Ventilation : 

Advanced modes- Closed Loop Ventilation Closed Ventilation-ASV/PAV+/NAVA Clinician Ventilator Patient % of support/ parameters are set- there is sharing of information between the ventilator and the patient which leads to change in every delivered breath appropriate to patients lung characteristics –Resistance / compliance /Edi Ventilator Adapts to the patient Information is feed back from pt to vent

Advanced Closed Loop Ventilation : 

Advanced Closed Loop Ventilation Advanced Closed Ventilation- Smartcare/NeoGanesh Clinician Ventilator Patient Intensivists brain What SmartCare/PS does Monitor the patient for at least 15 min Classify situation into one of 8 diagnoses A clinical protocol is stored in the knowledge base Adjust Pressure Support. Step width varies based on actual pressure, humidification etc.

Anything close to normal physiology is Advanced : 

Anything close to normal physiology is Advanced What is close to physiology in positive pressure ventilation? Ventilation starts /ends / and is as much as the brain wants

What is close to physiology in positive pressure ventilation? : 

What is close to physiology in positive pressure ventilation? Neural inspiratory time = Ventilatory inspiratory time Neural Expiratory time = Ventilatory Expiratory time Support is Proportional to what patient wants How can this be done?

Slide 20: 

NAVA PAV+/ASV Respiratory center output Peripheral nerve transmission Muscle Electrical activation Contraction Lung distension Respiratory compliance Airway resistance Airway opening pressure Flow/volume Alveolar ventilation Gas exchange Blood gases Proportionality of support means Support stats and ends and is as much as the Brain wants Chemo receptors Lung and airway reflexes Respiratory muscle afferents If ventilator uses any of These parameter to alter Breath pattern then ventilation will Be more synchronized and Proportional to what brain wants

Proportional Assist : 

Proportional Assist Airway assistance

Slide 22: 

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+

What are the problems with conventional modes ? : 

What are the problems with conventional modes ? Trigger delay/Synchrony issues

Phases of ventilatory cycle : 

Phases of ventilatory cycle Delay, Missed breaths Flow not proportionate to patients effort -dyssynchrony/overassist VIDD/ Runway Asynchrony can occur at the start of a breath (trigger asynchrony Asynchrony can occur during the breath (flow asynchrony Asynchrony can occur at the end of a breath (cycle or termination asynchrony).

Old modes trigger delay : 

Old modes trigger delay

Trigger in conventional modes : 

Trigger in conventional modes Time delay

Slide 27: 

Ventilator TE Neural TI Neural TE Trigger delay Ventilator TI Asynchrony Synchrony BRAIN Ventilator Missed breaths/flow asynchrony Runways INS/Exp Cycling asynchrony

Trigger delay/Cycle issues : 

Trigger delay/Cycle issues

NAVA Neurally adjusted ventilatory assist : 

29 NAVA Neurally adjusted ventilatory assist Recorded electrical activity of the diaphragm % of support is based upon a gain factor, set by the clinician, which translates a given electrical activity of the diaphragm into pressure assist Translates into a positive relationship between ventilator assistance and patient effort

NAVA : 

NAVA

NAVA-what the brain wants? : 

NAVA-what the brain wants? Output is after analysing many inputs

Slide 32: 

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) Pes (cm H2O) Paw (cm H2O) Missed breaths

Better synchrony : 

Better synchrony Studies prove Better quality of sleep and less arousals- PAV+/NAVA Patient may do more work (WOB) on ventilator if there is dys-synchrony between the ventilator and the patient

A possible case scenario… : 

A possible case scenario… Patient on PS mode 14 cms of H2O and PEEP 7 cms of H2O has a RR 30 with VT of 7 ml/kg What will we do? We think RR is more because PS is less and Increase PS What happens?

Proportional support is vital : 

Proportional support is vital No Diaphragm activity Missed breaths Over assist leads to increased Tidal volume Auto PEEP –missed breaths and also decreased diaphragm activity Possibly to much pressure support which had suppressed the diaphragmatic activity Increase the PS

Automated mechanical ventilation is the future : 

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

Automated mechanical ventilation is the future : 

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

Striving for better outcomes: : 

Striving for better outcomes: The three • Spontaneous breathing (Girard 2008; MacIntyre 2000, Levine 2008) • Synchrony (Chao 1997;Thille 2006; De Wit 2009) • Sedation management (Kress 2000, Girard 2008, De Wit 2009) “S”s All reduce time on mechanical ventilation

Slide 39: 

Short of staff Closed loop = Less work in ICU Quick weaning = Short stay in ICU Easy to use = Less need for specialists

The Future of Mechanical Ventilation : 

The Future of Mechanical Ventilation Automated mechanical ventilation is the future

My classification of new MODES : 

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

Arguments Against New Modes : 

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?

Better oxygenation, faster weaning, lesser sedation, less Asynchrony YES- BUT mortality benefit not proved : 

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 Smartcare-unique mode can say ventilator has intensivist’s brain-good evidence for weaning

Why New Modes? : 

Why New Modes? Address important clinical issues: Poor trigger Proportional assist to match patients effort Improve patient - ventilator synchrony! Less sedation/NM blockers-VAP/VIDD/CCIW 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) We do not have a single mode which does all these Some have a few of Them- So the quest is still on….. Noisy breathing

I will discuss these modes : 

I will discuss these modes VAPS PAV+, BIPAP Smartcare NAVA /APRV

DUAL MODESVAPS : 

DUAL MODESVAPS

Slide 47: 

Lung Compliance Changes and the P-V Loop Volume (mL) PIP levels Preset VT Paw (cm H2O) Volume Targeted Ventilation COMPLIANCE Increased Normal Decreased

Volume Control : good and bad : 

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

Slide 49: 

Lung Compliance Changes and the P-V Loop Volume (mL) Preset PIP VT levels Paw (cm H2O) COMPLIANCE Increased Normal Decreased Pressure Targeted Ventilation

Pressure Control :good and bad : 

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

Slide 51: 

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

Slide 52: 

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

Dual Modes : 

Dual Modes Volume target achieved-can target a pressure limit Issues not addressed Trigger delay No Proportional support-VIDD/fatigue Not taking into account lung mechanic’s resistance/compliance Not physiological -asynchrony

PAV+/PPS : 

PAV+/PPS

PAV +(Proportional Assist Ventilation) : 

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

Slide 56: 

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+

Slide 57: 

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+

Slide 58: 

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

Slide 59: 

+ 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

Slide 60: 

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 (TEF). Children

APRV/BIPAP/DUOPAP : 

APRV/BIPAP/DUOPAP

Conventional Ventilation in ALI/ARDS : 

Conventional Ventilation in ALI/ARDS Low PEEP - Normal VT High PEEP - Normal VT High PEEP - Low VT de- recruitment shear force injury overdistention volutrauma hypercapnia heavy sedation

APRV/BIPAP : 

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 IRV less synchrony problems Keeps the lung in lung protective zone Zone of Atelectasis

Spontaneous ventilation in assisted breaths : 

Spontaneous ventilation in assisted breaths Diaphragm with sedation P abdominal Area of increasedventilation Area ofincreasedperfusion Risk of over distention Risk ofatelectasis Good ventilated area Area with good perfusion R ! R ! R ! Spontaneousbreathing Diaphragm withlow sedation1 Spontaneous ventilation in assisted breaths Controlled ventilation Better V/Q Less VILI

APRV settings : 

APRV settings Paw Thigh (4-5) Sec Tlow Phigh Plow( 1 sec) Time-triggered, Time-cycled, Pressure-limited, Spontaneous breathing is allowed at any point during the ventilatory cycle FLOW Phigh -This parameter is set with the goal of improving oxygenation. Plow -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 or more) Inverse ratio ventilation

BiLevel Ventilation: : 

BiLevel Ventilation: Uses 2 pressure levels for 2 time periods PEEPlow & PEEPhigh, Thigh and Tlow Patient triggering & cycling can change phases If PS is set higher than PEEPH, the PS pressure is applied to a spontaneous effort at upper pressure From PB product lit. If set PS < than Phigh then only applied in the lower pressure level

5 possible breath types in BIPAP : 

5 possible breath types in BIPAP High incidence of asynchrony issues

Spontaneous breaths in assisted ventilation : 

Spontaneous breaths in assisted ventilation Increased Transpulmonary pressure Difference between the alveolar pressure and the intrapleural pressure in the lungs (Palv-Ppl) Transpulmonary pressure is the main determinant of VILI

Pplat = Palv; Pplat = Transpulmonary Pressure? : 

transpulmonary pressure = 45 cm H2O Pplat = Palv; Pplat = Transpulmonary Pressure? 0 5 10 15 20 25 30 -5 -10 -15 45 cms of H2O

Different factors may promote reduced lung injury during assisted ventilation : 

Different factors may promote reduced lung injury during assisted ventilation Recruitment of dependent atelectatic lung regions, reducing shear stress forces; More homogeneous distribution of regional transpulmonary pressures; Variability of breathing pattern; Redistribution of perfusion towards non-atelectatic injured areas Improved lymphatic drainage

Smartcare/NeoGanesh : 

Smartcare/NeoGanesh Complete Closed Loop Automates clinical protocols

SmartCare/NeoGanesh : 

SmartCare/NeoGanesh Is an automated weaning system that controls the ventilator in order to stabilize a patient’s spontaneous breathing in a “comfortable zone” and to reduce inspiratory support until the patient can be extubated.

The “Zone of Respiratory Comfort” or “ZoRC” : 

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.

SmartCare/PSBack-on-track : 

74 SmartCare automated weaning | Hartmut Schmidt | 10.Jan.2007 SmartCare/PSBack-on-track If the patients deviate from normal ventilation, SmartCare stabilizes the patients and brings themback-on-track.

Smartcare : 

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

SmartCare- the clinical evidence : 

SmartCare- 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%

New Modes of Mechanical Ventilation: Summary : 

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

The Evidence for New VentilatorModes … : 

The Evidence for New VentilatorModes … 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

Thank you : 

Thank you Innovation and Automation is the future