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venti modes.pptx
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- 2. GOALS 1. SAFETY –no VILI /CILI – acute phase 2. COMFORT – low sedation, good synchrony - stablisation phase 3. LIBERATION – early weaning – stablisation and recovery phase of disease
- 3. COMPONENTS OF BREATH A.Start (inspiration) = TRIGGER B. Maintain /fixed = LIMIT C. End of inspiration =CYCLE D. Expiration A B C
- 4. TRIGGER VARIABLES 1. Machine= time :- based on the set time interval 2. Pt – pressure / flow / neural • Pressure - patient assisted :- based on the drop in airway pressure • Flow - patient assisted :- flow triggering strategy uses a combination of continuous flow and demand flow • Neural – newer modes (NAVA)
- 5. LIMIT VARIABLES • Ifone of variables (pressure, volume or flow) is not allowed to rise above a preset value during inspiratory time, it is termed a limit variable. • The breath delivery continues, but the variable is held at the fixed preset value. • TYPES- Pressure limit Flow limit Volume limit
- 6. CYCLE VARIABLES • Ameasurement that causes the end of inspiration. This variable must be measured by the ventilator and used as feedback signal to end inspiration and then allow exhalation to begin. It can be:- Pressure-cycled Volume-cycled Flow-cycled Time-cycled
- 8. BASICS SHAPES OFWAVEFORM • Square • Ramp • Sine wave
- 9. SCALARS Plotted against time(x axis) Press-time Flow-time Volm-time
- 10. LOOPS Plotted against volume •Press-volm • Flow-volm
- 11. CONTROLLED MANDATORY VENTILATION (CMV) Alsoknown as continuous mandatory or control mode. The ventilator delivers the preset tidal volume or pressure at a set time interval (time-triggered frequency). Indications: Initial stages of mechanical ventilation when patient fights the ventilator. DISADVANTAGES – NEED FOR EXESSIVE NMBs – cinm, muscle atrophy
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- 13. ASSIST/CONTROL(AC) • In assist/control(AC)mode the patient may increase the frequency(assist) in addition to the preset mechanical frequency(control). Each assist breath provides the preset mechanical tidal volume.
- 14. Indications: • Used toprovide full ventilatory support for patients when they are first placed on mechanical ventilation. • Typically used for patients who have a stable respiratory drive( stable spontaneous frequency of at least 10 to 12/min)& therefore trigger ventilator into inspiration. Requirement: synchrony
- 15. VOLUME CONTROL MODE •Set volm is delivered with each breath • Volm delivery fixed, pressure will very, depending upon pulmonary compliance and airway resistance TRIGGER – time LIMIT – flow CYCLE - volume
- 16. • Advantage –can regulate tidal volm and minute ventilation • Disadvantage – 1) Variable PIP based on lung mechanics- Barotrauma
- 17. 2) Related toflow and sensitivity setting which may lead to pt venti asynchrony. Constant flow may not match pt demand.
- 18. PRESSURE TIME SCALARIN VOLUME CONTROL
- 20. PRESS CONTROL • Allowsclinicians to set a maximum pressure level • Using this mode would reduce the peak inspiratory pressure while still maintaining adequate oxygenation(PaO2) and ventilation(PaCO2) therefore reducing the risk of barotrauma in such patients. • The pressure controlled breaths are time trigggered by a preset respiratory rate. • Once inspiration begins, a pressure plateau is created and maintained for a preset inspiratory time. • Pressure controlled breaths are therefore time triggered, pressure limited and time cycled.
- 21. • Decelerating flowpattern • More comfortable for spontaneously breathing pts • Disadvantage: Volm delivery varies
- 22. PRESSURE SUPPORT VENTILATION(PSV) • PSV is used to lower the work of spontaneous breathing and augment the spontaneous tidal volume. • PSV applies a preset pressure plateau to the patient’s airway for the duration of spontaneous breathing. 1. TRIGGER - pt 2. LIMIT – pressure 3. CYCLE – flow (breath cycles when flow reaches some proportion of peak flow say 25%)
- 24. Dual Control Breath-to-Breath pressure-limitedtime-cycled ventilation Pressure Regulated Volume Control Servo 300 Maquet Servo-i
- 25. PRESSURE REGULATED VOLUMECONTROL • Closed loop system • Matches pt.’s demand • Ventilator measures VT delivered with VT set on the controls. If delivered VT is less or more, ventilator increases or decreases pressure delivered until set VT and delivered VT are equal
- 26. • Delivers patientor timed triggered, pressure-regulated (volume controlled) and time- cycled breaths
- 27. PRESSURE REGULATED VOLUME CONTROL •The ventilator will not allow delivered pressure to rise higher than 5 cm H2O below set upper pressure limit Example: If upper pressure limit is set to 35 cm H2O and the ventilator requires more than 30 cm H2O to deliver a targeted VT of 500 mL, an alarm will sound alerting the clinician that too much pressure is being required to deliver set volume (may be due to bronchospasm, secretions, changes in CL, etc.)
- 28. PRVC Measure VT Compare to setVT Same inspiratory pressure inspiratory pressure inspiratory pressure Test breath Less Equal More
- 29. PRVC (Pressure RegulatedVolume Control) PRVC. (1), Test breath (5 cm H2O); (2) pressure is increased to deliver set volume; (3), maximum available pressure; (4), breath delivered at preset E, at preset f, and during preset TI; (5), when VT corresponds to set value, pressure remains constant; (6), if preset volume increases, pressure decreases; the ventilator continually monitors and adapts to the patient’s needs
- 30. PRVC (Pressure RegulatedVolume Control) • Disadvantages and Risks • Varying mean airway pressure • May cause or worsen auto-PEEP • When patient demand is increased, pressure level may diminish when support is needed • A sudden increase in respiratory rate and demand may result in a decrease in ventilator support
- 31. PRVC (Pressure RegulatedVolume Control) • Indications • Patient who require the lowest possible pressure and a guaranteed consistent VT • ALI/ARDS
- 32. PRVC (Pressure RegulatedVolume Control) • Advantages • Maintains a minimum PIP • Guaranteed VT • Decreases WOB • Allows patient control of respiratory rate • Decelerating flow waveform for improved gas distribution • Breath by breath analysis
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