Ventilatory Modes Graphnet Ventilator

Mechanical Ventilation Goal Generate a Minute Volume Gases with a controlled FiO2 Avoiding: Lung damage Hemodynamic interference Exesive Work of Breathing Graphnet Ventilator

What is a Ventilatory Mode? It´s the way in which the ventilator accomplish the goals of mechanical ventilation. Graphnet Ventilator

Ventilatory Modes Classification Control Variables Control the inspiration Constant behavior Non controlled variable modification PRESSURE Controlled Modes FLOW Controlled Modes VOLUME Controlled Modes Graphnet Ventilator

Pressure Controlled Modes The PRESSURE is the variable controlled by the ventilator. It is constant during all Ti. The ventilator try to reach and maintain a preset inspiratory pressure What happen with the non controlled variables? Preset pressure Respiratory impedance Circuit impedance Inspiratory effort Volume and Flow will change according Graphnet Ventilator

Pressure controlled modes Constant Pressure Variable Flow Flow /Time Pressure/Time Graphnet Ventilator

Flow Controlled Modes The FLOW is the controlled variable. The VOLUME is also controlled in an indirect way: ( VT = Flow x Ti) Rectangular – Decreasing ramp Sinusoidal - Accelerated The flow waveform can be changed What happen with the non controlled variables? Preset flow or volume Respiratory impedance Circuit impedance Inspiratory effort The airway PRESSURE will change according: Graphnet Ventilator

Flow Controlled Modes VariablePressure Constant Flow Pressure/Time Flow/Time Graphnet Ventilator

Volume Controlled Modes Piston or bellows displacement Controlled by a direct volume signal. Modern ventilators control volume in an indirect way by an integration of flow and time Traditionally the flow controlled modes are also called VOLUME controlled modes Graphnet Ventilator

Volume or Flow Control Pressure Control Variable Pressure Constant Pressure Constant volume Variable volume Constant inspiratory flow Variable inspiratory flow Volume or Flow Control Pressure Control Graphnet Ventilator

Phase variables Trigger Time - Pressure – Flow – Volume These are the signals used by the ventilator to determine when a respiratory cycle phase must start or end Trigger Time - Pressure – Flow – Volume Limit Pressure – Flow - Volume Cycling Time - Flow – Pressure – Volume Base Pressure (PEEP) Graphnet Ventilator

Phase Variables Pressure Control Ventilation mode Limit Cycling Base 1 2 3 4 5 6 SEC Paw cmH2O 60 -20 120 INSP EXH Flow L/min Limit Trigger Cycling Base Phase Variables Pressure Control Ventilation mode Graphnet Ventilator

Graphnet Ventilator

How a ventilator can be triggered? Respiratory Frecuency It can be triggered by: Time (Controlled Ventilation) Patient (Assisted or Spontaneous Ventilation) Respiratory Frecuency Sensitivity Pressure or Flow Graphnet Ventilator

Where to look? Assisted Controlled (Pressure or Flow) (Time) Graphnet Ventilator

Pressure trigger Pressure Which one is the most sensitive setting ? Which one is the most sensitive setting ? -0.5 or -10 Trigger (Sensitivity) Pressure Patient´s effort Sensitivity tthreshold Post trigger response (Ventilator´s flow) Baseline Graphnet Ventilator

Which one is the most sensitive setting? Flow trigger WITH patient effort Patient NO patient Sensitivity: 1 L/min 4 3 Setting: from 0.5 to 15 L/min Which one is the most sensitive setting? Graphnet Ventilator

Cycling (End of inspiration) Volume controlled mode Pressure Controlled modes (PSV) Cycling (End of inspiration) Volume Flow Time (PCV) (VCV) Graphnet Ventilator

PEEP Positive End Expiratory Pressure Restore FRC Avoid alveolar collapse Improve V/Q ratio Correct Hipoxemia Improve trigger with AutoPEEP Graphnet Ventilator

Conditional Variables Variables analyzed by the ventilator´s logic control and used to determine some criteria used to manipulate any phase of the respiratory cycle Use sentences “ IF THEN “ “Closed Loop” Modes Graphnet Ventilator

Respiratory Period Inspiration (Ti) Expiration (Te) (Ti/Tot) End Inspi Trigger Pause Inspiration (Ti) Expiration (Te) Inspiratory Flow Expiratory Flow Graphnet Ventilator

According the Control Variable Ventilatory Modes According the Control Variable Flow or Volume Controlled Modes Pressure Controlled Modes Dual Controlled Modes (non conventional) Graphnet Ventilator

Type of breathing Mandatory Breath Started by the ventilator or the patient and ended by the ventilator. Sponteneous Breath Started and ended by the patient Graphnet Ventilator

Graphnet Ventilator

PRVC Pressure Regulated Volume Control Dual Control mode Pressure Control with a target VT Assist/Control Maximum Limit: Pmax – 5 cmH2O Minimun PCV 5 cmH2O Graphnet Ventilator

VCV asist/control Volume Controlled Ventilation Trigger: patient (assist) or time (control) Pressure: variable and influenced by the patient´s respiratory mechanics. Risk of excessive alveolar pressure Volume: preset and guaranteed Cycling: volume Inspiratory Flow: Controlled and fixed Possibility to change the waveform It can generate patient-ventilator asynchrony Graphnet Ventilator

Different waveforms . Volume Control Ventilation Paw Vt V Square or rectangular Decreasing ramp Sinusoidal Paw Vt V . Volume Control Ventilation Graphnet Ventilator

Graphnet Ventilator

VCV The most common problem….. Disadvantages Excessive pressure Asynchrony Increased WOB Advantages Experience VE Guaranteed and predictable The most common problem….. Mismatch between patient´s demand and inspiratory flow Graphnet Ventilator

VE VT (set) Flow Ti F Te Period I : E Graphnet Ventilator

Flow set: Ti set: Flow / 2 Ti x 2 Flow x 2 Ti / 2 I:E is modified Ti / 2 Flow x 2 Ti x 2 Flow / 2 I:E is modified Te: Frecuency x2 Te / 2 I:E is modified Graphnet Ventilator

PCV asist/control Pressure Controlled Ventilation Trigger: patient or time Pressure: controlled and preset Less risk of barotrauma Cycling: time Volume : variable and influenced by the patient´s respiratory mechanics and effort , the preset pressure and Ti. Inspiratory flow: variable and decelerated Influenced by the respiratory mechanics Deceleration is close related to Time Constant Improves patient-ventilatos synchrony Graphnet Ventilator

Graphnet Ventilator

VE Ti Te I : E Raw VT F.R. CT Crs Rise Time P PEEP (set) MAP P Graphnet Ventilator

“Rise Time” Graphnet Ventilator

Pressure Controlled Modes Modes: PCV and PSV Disadvantages VT variable VE unpredictable VT influenced by impedance Advantages Mean pressure Barotrauma Better distribution WOB Graphnet Ventilator

Pressure Support Ventilation PSV Pressure Support Ventilation Trigger: patient only Pressure: controlled and preset Less risk of barotrauma Volume : variable and influenced by the patient´s respiratory mechanics and effort , the preset pressure and Ti. Inspiratory flow: variable and decelerated Influenced by the respiratory mechanics Deceleration is close related to Time Constant Improves patient-ventilatos synchrony Cycling: Flow (default) Pressure (safety), Time (safety) Graphnet Ventilator

Graphnet Ventilator

PSV Variable End Inspiration criteria (Expiratory Sensitivity) Graphnet Ventilator

PSV Advantages Disadvantages Similar to PCV Work of breathing reduction Better synchrony Less sedation requirements Disadvantages Variable volume Asynchrony in some COPD patients Graphnet Ventilator

Sinchronized Intermitent Mandatory Ventilation (SIMV) Synchronized combination of mandatory and spontaneous breaths. The mandatory breaths are delivered according the preset respiratory frecuency and they are synchronized with the patient´s respiratory effort The patient determines the tidal volume and the frequency of the spontaneous breaths Graphnet Ventilator

Graphnet Ventilator

Graphnet Ventilator

Graphnet Ventilator

Ventilation Mandatoria Intermitente (SIMV) Respiración mandatoria VCV Respiración espontánea con CPAP 0 con Presión de Soporte SIMV VCV + CPAP 0 SIMV VCV + PSV Graphnet Ventilator

CPAP Inspiration Paw (cmH2O) Expiration Graphnet Ventilator sec 16 14 8 10 12 14 16 Paw (cmH2O) sec Expiration Inspiration Graphnet Ventilator

Graphnet Ventilator

CPAP The patient must have spontaneous breaths. This is not a respiratory support mode Same physiological effects that PEEP. Tidal volume and frecuency determined by the patient Commonly used as a pre extubation test. Graphnet Ventilator

Closed Loop Modes Mandatory Minute Volume PRVC Inter breath dual control Pressure controlled and flow cycled Similar to PRVC, but with a VE target PRVC Pressure controlled and time cycled with a VT target PSV + Assured Tidal Volume Intra breath dual control PSV with a MINIMUM tidal volume as target Graphnet Ventilator

Graphnet Ventilator

PSV + Assured Tidal Volume Constant Pressure (Pressure Controlled phase) Variable Pressure (Flow Controlled phase) Transition point Decelerated Flow (pressure Controlled phase) Continuous Flow (Flow Controlled phase) Graphnet Ventilator

Graphnet Ventilator

Graphnet Ventilator

PRVC Pressure Regulated Volume Control Dual Control mode Pressure Control with a target VT Assist/Control Maximum Limit: Pmax – 5 cmH2O Minimun PCV 5 cmH2O Graphnet Ventilator

Graphnet Ventilator

Graphnet Ventilator

APRV 2 levels of CPAP with intermitent pressure release. Spontaneous breaths Higher Mean pressure CO2 removal. Graphnet Ventilator

Graphnet Ventilator

APRV Two CPAP levels (Hi and Lo) Intermitent pressure release toward a lower pressure level Two different CPAP times (TiHi and TiLo) Spontaneous breaths possible in any moment of the respiratory cycle (Active Expiratory Valve) PSV can be added to spontaneous breaths Graphnet Ventilator

APRV Advantages Better gaseous exchange Dead space reduction Less sedation requirements Better hemodynamics Less risk of barotrauma Graphnet Ventilator

Ventilatory Modes