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How To Ventilate ICU Patient. Dr Mohammed Bahzad MBBS.FRCPC,FCCP,FCCM Head Of Critical Care Department Mubarak Alkbeer Hospital. Aims. Get oxygen in Get carbon dioxide out Minimize adverse effects Maximize patient comfort. Case A. 60 kg male
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How To Ventilate ICU Patient Dr Mohammed Bahzad MBBS.FRCPC,FCCP,FCCM Head Of Critical Care Department Mubarak Alkbeer Hospital
Aims • Get oxygen in • Get carbon dioxide out • Minimize adverse effects • Maximize patient comfort
Case A • 60 kg male • Post operative – complicated wipel procedure • No previous lung or heart disease • Still paralyzed
Mode • Non-invasive • Invasive • Assist control • Pressure control • SIMV • (Pressure support) • Pick a mode you understand and are familiar with
Assist control • Set tidal volume • Inspiratory-expiratory cycling • Time cycled • Time is set • Ventilator adjusts flow to deliver set tidal volume in the set time • Volume cycled
Assist control • Breaths: • Ventilator initiated (control breaths) • Patient initiated (assist breaths) • Set minimum frequency • Characteristics of each inspiration are the same • Not affected by whether breath is control breath or an assist breath
Assist control T 50 cmH2O Pressure 70 l/min Flow -70 700 ml Volume
Assist control T 50 cmH2O Pressure 70 l/min Flow -70 700 ml Volume
Assist control • Set • Minimum respiratory rate • Patient’s spontaneous respiratory rate < set rate ventilator gives additional control breaths to make up difference • Patient’s spontaneous rate > set rate no control breaths
Volume control • Set • Minimum respiratory rate • Tidal volume
Volume control • Set • Minimum respiratory rate • Tidal volume • Inspiratory time or I:E ratio • Inspiratory pause time
Volume control • Longer inspiratory time • Improved oxygenation • Higher mean airway pressure • Re-distribution • Lower peak airway pressure • More time available to deliver set tidal volume • Shorter inspiratory time • Less risk of gas trapping and PEEPi • Less effect on cardiovascular system
Setting I:E, inspiratory flow time, pause time • Nomenclature Volume Time
Setting I:E, inspiratory flow time, pause time • Nomenclature Inspiratory flow time Volume Time
Setting I:E, inspiratory flow time, pause time • Nomenclature Inspiratory pause time Volume Time
Setting I:E, inspiratory flow time, pause time • Nomenclature Inspiratory time Volume Time
Setting I:E, inspiratory flow time, pause time • Nomenclature Inspiratory time Expiratory time Volume Time
Setting I:E, inspiratory flow time, pause time • Nomenclature Respiratory cycle time Volume Time
I:E as a ratio & inspiratory pause time as a percentage 6 secs 1 2 10% Volume Time
I:E as a ratio & inspiratory pause time as a percentage 3 secs 1 2 Respiratory rate 10% Volume Time
Absolute inspiratory time, inspiratory flow time as a function of flow rate 6 secs 2 secs 4 secs 0.5 s Volume Time
Absolute inspiratory time, inspiratory flow time as a function of flow rate 3 secs 2 secs 1 sec Respiratory rate withoutchanging Inspiratory time orinspiratory flow 0.5 s Volume Time
Absolute inspiratory time, inspiratory flow time as a function of flow rate 3 secs 2 secs 1 sec inspiratory flow 1.5 s Volume Time
Absolute inspiratory time, inspiratory flow time as a function of flow rate 3 secs 1 sec 2 sec Absolute inspiratory time 0.5 s Volume Time
Inspiratory flow time as a function of flow rate, absolute pause time 3 secs 2 secs 1 sec Respiratory rate withoutchanging inspiratory flow orinspiratory pause time 0.5 s Volume Time
Inspiratory flow time as a function of flow rate, absolute pause time 3 secs 1 sec 2 sec inspiratory flow 0.5 s Volume Time
Inspiratory flow time as a function of flow rate, absolute pause time 3 secs 0.8 sec 2.2 sec inspiratory pause time 0.3 s Volume Time
Volume control • Set • Minimum respiratory rate • Tidal volume • Inspiratory time or I:E ratio • Directly/indirectly • Inspiratory pause time • Directly/indirectly • PEEP
Advantages Relatively simple to set Guaranteed minimum minute ventilation Rests muscles of respiration (if properly set) Disadvantages Not synchronized Patient may “lead” ventilator Inappropriate triggering may result in excessive minute ventilation lung compliance alveolar pressure with risk of barotrauma Often requires sedation to achieve synchrony. Assist control
Pressure control • Pressure preset assist/control ventilation • Similar to volume control except pressure is preset
PC above PEEP Pressure PEEP Time Flow Time Volume Time
Normal inspiratory time Short inspiratory time PC above PEEP Pressure PEEP Time Flow Time Volume Time
Advantages Relatively simple Avoids high inspiratory pressures Rests muscles of respiration Improved oxygenation Disadvantages Not synchronized Inappropriate triggering may excessive minute ventilation Change in lung compliance or resistance change in tidal volume Often requires sedation Pressure control
Pressure support • Nomenclature • Inspiratory assist • Assisted spontaneous breathing
Maximum inspiratoryflow Set % of maxinspiratory flow Pressure support PS above PEEP Pressure PEEP Flow Volume
Advantages Simple to set Avoids high inspiratory pressures Better patient-ventilator synchrony Unloads respiratory muscles Disadvantages No apnoea back-up in older ventilators Change in lung compliance or resistance change in tidal volume Pressure support
Pressure support • Pressure support of 3.5-14.5 cmH2O required to overcome the additional work of breathing due to breathing through ETT and demand valve • Patients who require pressure support of < 6 cmH2O can probably be extubated
SIMV (& pressure support) • SIMV almost always combined with pressure support
SIMV • Patient receives a minimum number of mandatory breaths • Able to breath in between these breaths • ± pressure support breaths
SIMV Mandatory breath Pressure PEEP Time Flow Time Trig Trig
SIMV Pressure support breath Pressure PEEP Time Flow Time Trig Trig
Mandatory breaths • Volume control breaths • Set tidal volume • Pressure control breaths • Set pressure
Mandatory breaths • Synchronized with patients inspiratory efforts
Triggering • Effect of triggering depends on its timing • Close to time that a mandatory breath is due (during SIMV period) • ⇒synchronized mandatory breath • Other times (during spontaneous period) • ⇒pressure support breath
Spontaneous period SIMV period T T
Spontaneous period SIMV period
Settings • FiO2 • SIMV rate • =mandatory breath rate • SIMV period (some ventilators) • Tidal volume (or inspiratory pressure) • I:E ratio • Pressure support • PEEP
Volume control • Set • Minimum respiratory rate • Tidal volume • Inspiratory time or I:E ratio • Directly/indirectly • Inspiratory pause time • Directly/indirectly • PEEP