Nonconventional Modes of Ventilation VIJAY DESHPANDE, MS, RRT, FAARC Emeritus Professor Adjunct Professor Georgia State University Manipal University Atlanta, Georgia Manipal, Karnataka USA India Evolution of Mechanical Ventilation■ Resuscitation Bags■ Negative Pressure Ventilation ( Iron Lung etc.)■ Pressure Cycled Ventilators ( Bird, Bennett etc.)■ Volume Ventilators (Bennett MA-1, Bear 1, Emerson Post-op)■ SIMV Ventilators ( Siemens 900 C etc.)■ Third Generation Ventilators ( PB 7200,■ Hamilton Veolar, Bird 6400 etc.)■ Microprocessor Ventilators ( Siemens 300,■ Hamilton Galileo, Bird 8400 ST, Bear 1000 etc.)
Advancements in Mechanical VentilationControl, Assist, PEEP, CPAP VENTILATOR CLOSED-LOOP IMV, GRAPHICS VENTILATION SIMV, PSV, PCV, Combinations of Volume or Pressure VAPS, Paug ventilation: Volume Support, SIMV +PSV, PRVC, Auto-flow, SIMV+PSV+CPAP ASV,APV, VS, auto mode PAV, NAVA How is Closed Looping Accomplished ? I have absolutely no idea.
Flow Sensor Flow Sensor Flow Triggering CHURCH BULLETIN BLOOPERS A bean supper will be held on Tuesday evening in the church hall. Music will follow.
Decision Making After initiating SIMV, within an hour the ABGs return to normal levels, however the patient demonstrates use of accessory muscles and increased work of breathing.Unsupported Breathing through a Tracheal Tube
SIMV + PS (Pressure-Targeted Ventilation) Time-Cycled Time- Flow-Cycled Flow (L/min) Set PC level Pressure Set PS level (cm H2O) Volume (ml) Time (sec) PS Breath Acute Lung Injury (ALI)ALI is described as:● Acute onset of Hypoxemia with P/F ratio of </= 300 mm Hg● Bilateral infiltrates on a frontal Chest Radiogram● Absence of Left Atrial Hypertension (Normal PCWP )● ALI with most severe hypoxemia with P/F ratio < / = 200 mm Hg is termed as ARDS
ALI and ARDS ● Approximate incidence of 59 (ALI) and 29 (ARDS) cases per 100,000 persons/year ● Mortality ~ 34-58 % ● Economic burden on Uninsured, inadequately insured patients, Hospitals, Government and Insurance Companies Lung Protective Ventilation NEJM 2000; 342 (18) : 1301-1308● Small V T and Low Airway Pressures is the only intervention found to reduce mortality from ALI/ARDS● May promote progressive lung derecruitment and worsening of oxygenation
Recruitment Maneuver● Recruitment refers to reopening collapsed lung units using transient increase in the transpulmonary pressure● The rationale for recruitment maneuvers is to improve alveolar recruitment and increase end-expiratory volume in order to: a. Improved gas exchange b. Reduced overdistension of relatively healthy lung units c. Prevent repetative opening and closing of unstable alveoli ARDS s Acute Respiratory Distress Syndrome s Pulmonary endothelial Inflammation leading to Acute Lung Injury s Further deterioration promotes ARDS
ARDSs Inflammatory response promotes: increased pulmonary vascular permeability seepage of proteinaceous fluid into the pulmonary interstitium and alveoli reduction in Surfactant production and inactivation of existing Surfactant increased surface tension microatelectasis in the affected areas The American-European Consensus Conference on ARDS. Am J Respir Crit Care Med 1994; 149:818-824
Dilemma in Ventilatory Management of ARDS Objective: Reopen collapsed and recruitable alveoli Strategy: Application of Positive Pressure Ventilation Commonly used Mode of Ventilation: Volume Targeted Problem: Alveolar Overdistention
Oh! Sh*! Acute Lung Injury (( ALI )) and ARDS Acute Lung Injury ALI and ARDSDamage to the Lung : G Not distributed homogenously G Even in severe cases ~ 1/3 lung is open G Open lung receives the entire tidal volume resulting in : Over-distention Over- Local hyperventilation Inhibition of surfactantsRavenscraft, Sue. Respiratory Care, Vol 41, No 2 : 105-111, Feb 105- 1996
ARDSC o lla p s e d R e c r u ita b le N orm al ARDS Volume Augmented Breath Collapsed Recruitable Normal
Over-distention Over-distention Preset Tidal Volume With little or With little or no change in VT no change in VT Normal Volume (ml) Abnormal Paw Paw Pressure (cm H2O) Over-distentionG Observed on a Pressure-Volume Loop Pressure-G Indicates hyperinflation or excessive application of pressureG May promote BarotraumaG Corrective action includes reduction in the Peak Inspiratory Pressure or Tidal Volume
CRITICAL THINKING 4 Common sense for an experienced therapist is critical thinking for a novice. 4 Critical thinking at the bedside is synonymous with “Differential diagnosis”.What shouldI do Now?
PRESSURE TARGETED VENTILATION d PIP and Palv are Limited d Prevents Alveolar Over- distention d Provides better Patient-Ventilator synchrony d Delivered Tidal Volume depends on Airway Resistance and Lung Compliance d PaCO2 is variable Assisted Mode (Pressure-Targeted Ventilation) (Pressure-TargetedPatient Triggered, Pressure Limited, Time Cycled Ventilation Time-Cycled Flow (L/min) Set PC levelPress(cm H2O) ureVolume (ml) Time (sec)
ARDS Pressure Augmented Breath P P P Collapsed Recruitable NormalARDS network.N Eng J Med 2000, 342(18):1301-1308.Multi-center NIH study demonstrated thatALI/ARDS patients ventilated with tidalvolumes of 6 ml/Kg were significantly morelikely to survive than those ventilated withtidal volumes of 12 ml/Kg.
ARDSnet Findings G Lower Tidal Volumes G Use of rapid rates avoiding auto-PEEP ( 35/min ) G PPLAT 30 cm H2O reduces mortality G Lower PPLAT showed better outcome ARDSnet: 6ml/kg reduces mortality vs. 12 ml/kg Components of Inflation Pressure PIPPaw (cm H2O) } Transairway Pressure (PTA) Exhalation Valve Opens Pplateau Inspiratory Pause (Palveolar) Expiration Time (sec) Begin Inspiration Begin Expiration
Strategies to Ventilate ALI and ARDS patientsG Prevent Alveolar Over-distention Use of low Tidal Volumes (5-7 ml/Kg) May promote de-recruitment of alveoliG Prevent repetitive alveolar opening and closure Use of Recruitment Maneuver sustained increase in airway pressure application of adequate end-expiratory pressure (PEEP/CPAP) Possible Approaches to Ventilate ARDS Patients G APRV G PCIRV G BiLevel or BiVent G PRVC G HFO No data to indicate that any mode of ventilation is BETTER than conventional Pressure-A/C ventilation
CHURCH BULLETIN BLOOPERSAt the evening service tonight,the sermon topic will be What Is Hell?Come early and listen to our choir practiceHow much PEEP?
Amato MB., et al., Effect of a protective-ventilationstrategy 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.
Lung Protective Strategy Volume (ml) PEEP 2-3 cm H2O above LIPLower Inflexion Point ( Pflex)The lower inflection point (Pflex)is obtained by static inflationmaneuver and should not bemeasured from the dynamic curve.
Initial PEEP Level2-3 cm H2O above the Lower Inflection Point CHURCH BULLETIN BLOOPERS The sermon this morning: Jesus Walks on the Water. The sermon tonight: Searching for Jesus.
Rationale for Closed Loop Ventilation Establish Homeostasis relatively faster Improve Quality of Care Improve Safety Address Resource Limitations Improve Quality and SafetyEstimated deaths in US due to medical error range from44,000 to 98,000 per year Improper use of mechanical ventilation has shown to havedetrimental effectsICU patients frequently have multiple system illnesses andrequire multiple testing and bedside decision makings Closed-Loop ventilation can prevent improper settingMarc Wysocki and Josef Brunner ; Closed-Loop Ventilation in Critical Care ClinicsVol 23, No 2, 223-237, April 2007
Address Resource Limitations Mechanical Ventilation is generally a labor intensive task On an average daily cost of Mechanical Ventilation is $ 1,500 Labor shortage or excessive work load per clinician is not uncommon Closed-Loop can provide care at lower labor cost Closed–Loop Ventilation can support clinicians with limited ability to incorporate data into decision makingMarc Wysocki and Josef Brunner ; Closed-Loop Ventilation in Critical Care ClinicsVol 23, No 2, 223-237, April 2007 Some actions do not correct auto-PEEP
Closed-Loop Ventilation PRVC, VC+, VAPS, PCV-VG ASV PAV, NAVAAdjust pressure to meet the Advanced Versionset Tidal Volume of PSV Incorporates several modes PSV, PCV, P-SIMV to deliver Appropriate VE Closed-Loop Ventilation General Scheme: PaO2 or output SpO2 RESPIRATORY FiO2 SYSTEM
Closed-Loop Ventilation Set P, V or flow RESPIRATORYComparator VENTILATOR SYSTEM Measured Pressure, Volume and Flow Generic Scheme
COMBINED PRESSURE/VOLUME VENTILATIONG Exploit beneficial effects of both Pressure and Volume VentilationG Improve Patient-ventilator Synchrony Patient-G Prevent ventilator induced lung injury
CHURCH BULLETIN BLOOPERSThis evening at 7 PM there will be a hymnsing in the park across from the Church.Bring a blanket and come prepared to sin Closed-loop Ventilation G Volume Support ( VS ) G Pressure Regulated Volume Control ( PRVC ) G Adaptive Support Ventilation ( ASV ) G Proportional Assist Ventilation ( PAV ) G Nuerally Adjusted Ventilator Assistance (NAVA)
Volume Support Patient Trigger Servo Trial breath to calculate Compliance i Pressure limit is set = VT/ C Breath Delivered Exhaled Volume Flow decreases to 5% measured of peak flow PS level is adjusted until Exhaled VT=Set VT Termination of Inspiration In case of apnea, the mode switches to PRVC PRVC Servo i Trigger On Exhaled VT Set VTExhaled VT Set VT Pressure Support level Pressure Support level increases stepwise decreases stepwise until until Exhaled VT = Set VT Exhaled VT = Set VT Servo 300 Ventilator, Maquet Inc.
Pressure Regulated Volume Control (PRVC) Volume Control+ ( VC + ) AutoflowAdaptive Support Ventilation (ASV)Pressure Control Ventilation with VolumeGuarantee ( PCV – VG)
AUTO- MODE Control Mode Support ModeDecrease Work of Breathing Facilitate Weaning Auto-ModeCoupling Modes to combine Control and SupportPressure Control Pressure SupportVolume Control Volume Support PRVC Volume Support
Adaptive Support Ventilation (ASV)The ASV assures a pre-selected target ventilationUses sophisticated calculations based on set tidalvolume, rate, and the patient’s lung mechanicsThe clinician sets: Desired minute ventilation Maximum Airway Pressure Prevents rapid shallow breathing and avoids volutraumaThe patient is protected from apnea and AutoPEEP Source: Hamilton Medical Proportional Assist ventilation (PAV)!Strictly a patient triggered mode!The ventilator adjusts pressure in response to patient effort!The clinician sets: IPAP EPAP Flow Assist Level PB 840 Volume Assist Level
0% 100 % CHURCH BULLETIN BLOOPERSLow Self-esteem Support Group will meetThursday at 7 PM.Please use the back door.
NAVANeurally Adjusted Ventilatory Assist Servo i Neural Pathway to Cural Diaphragm Neural pathways to the crural diaphragm.
NAVATrigger delay from inspiration to the beginning offlow from ventilator ~ 100 msInsuflation during exhalation and the trigger delaypromotes asynchrony in COPD and patientsrequiring high PSVia Electrical activity of the Diaphragm (Edi)NAVA provides full synchrony with therespiratory effort made by the patient
Clinical Benefits of NAVAReduce Work of BreathingAppropriate ventilationVariations in the amplitude of Edi preventexcessively high or low ventilationAdaptation to changes in metabolicdemandsAvoidance of diaphragmatic atrophyReduced weaning timeShortened hospital stay