Chapter 5 - Selecting Ventilator and Mode Flashcards
What are the percentages of patients connected to the ventilator?
ETT vs. Trach
ETT: 75%
Trach: 25%
What are 3 methods of Noninvasive Support?
- NPV
- CPAP
- NPPV
What is CPAP used for?
- Improve Oxygenation
- OSA
- Tx of COPD Exacerbation
Describe what Full Ventilatory Support is
Ventilator provides all the energy of ventilation
What are the Ventilator settings for Full Ventilatory Support?
- Normal Vt
- Normal RR
- Adequate alveolar ventilation
- AC/VC or AC/PC
Describe what Partial Ventilatory Support is
Ventilator provides some of the energy, but pt. must actively participate in WOB
What are the ventilator settings for Partial Vent Support?
- RR is 6 or less
- Vt is set for mandatory breaths, patient generated on spontaneous
- Pt needs to work to maintain normal or adequate alveolar ventilation
What is Partial Ventilatory Support not ideal for?
Pts with high WOB or muscle fatigue
What are modes determined by?
- Type of Breath
- Targeted Control variable
- Timing of Breath delivery
What are Mandatory Breaths?
Vent controls timing, Vt, or Both
What are Spontaneous breaths?
- Pt controls timing and Vt
- Affected by pt demand and lung characteristics
What are Assisted Breaths?
- Pt receives some support from vent
- When pressure on inspiration is higher than baseline (Pressure Support)
- Helps pt overcome some WOB
What occurs when Targeting Volume as the Control Variable?
- Guarantees Vt
- Maintains a minimum MV
- Volumes are unaffected by changes in lung characteristics and patient effort.
What are Hazards of Targeting Volume as the Control Variable?
Increased Peak Airway Pressures due to Increased Resistance and Decreased Compliance
What are Disadvantages of Targeting Volume as the Control Variable?
- Flow may be fixed on some ventilators
- Sensitivity may be set incorrectly
- Either of these can lead to Patient-vent. Dyssynchrony
What settings are allowed in Targeting Volume as the Control Variable?
-Vt, RR, I-Flow Rate, Flow Pattern
What are Advantages of Targeting Pressure as the Control Variable?
- Reduced risk of overdistention due to pressure control
- Descending flow pattern
- Pts I-Flow demands met with variable flow rates
- Reduction in WOB
What are Disadvantages of Targeting Pressure as the Control Variable?
-Variable Vt and MV
What occurs with Targeting Pressure as the Control Variable?
- Preset pressure target without guaranteed Vt
- Pressure is not affected by changes in lung characteristics
- Vol. WILL be affected by changes in lung characteristics
What occurs in CMV?
- All breaths are mandatory
- Ventilator(Controlled) or Patient(Assist/Control) triggered
- Set Rate ate Vt or Pressure
What is considered Controlled Ventilation?
- If pt does not trigger
- If pt is “locked out” from taking an extra breath
- If pt is medically prevented from assisting ventilation
What factors can trigger a breath with a fully sedated patient?
A Hiccup and Cardiac contraction
What occurs in Assist/Controlled Ventlation?
- Pt is triggering breaths over set rate
- Pt receives the preset vol or pressure when triggered
- Pt can become hyperventilated with excessive triggering
- May require increased lvls of sedation to reduce over triggering
What occurs in Volume-Targeted CMV?
- Set RR and Vt
- Not all work is done by vent unless settings are appropriate
- Pt can do up to 50% of WOB if flow rate is inadequate
- Flow must be set high so that pressure rise is immediate with the beginning of inspiration
What occurs in Pressure-Targeted CMV?
- Set RR and I-Pressure
- Improves WOB as pressure is immediate and variable to pts need
- Decelerating flow pattern helps gas distribution
- Vol is NOT guaranteed
What occurs in IMV?
- Delivers a set vol or pressure at set time intervals
- Allows pt to breath spontaneously btwn mandatory breaths
- Breath stacking occurs if pt was taking a spont breath at same time of a mandatory breath
What occurs in SIMV?
- Corrected breath stacking by placing mandatory breaths within a “time window”
- Mandatory breaths that are bent triggered by time interval or pt triggered by effort within a time window
- Pt takes spont breaths btwn mandatory breaths
- Spont breaths may be on CPAP or PS
- Used for weaning
What occurs in Spontaneous Modes?
- Spont breating
- CPAP
- PS
What occurs in Spontaeous Breathing?
- No suppot from vent
- Pt breaths through the circuit - T-piece
- Vent can monitor RR, Vt, MV, and alarm
- SBT (Spontaneous Breathing Trial)
What is a Disadvantage of Spontaneous Breathing?
Pt might have high WOB
What occurs in CPAP?
- Pt breaths spontaneously through the circuit
- Vent offers PEEP to prevent loss of FRC
- Helps improve oxygenation by preventing atelectasis
- Allows close monitoring of pts resp status
What occurs in PS?
- Pt Triggered, Pressure Limited, Flow Cycled
- Spont mode where breaths are assisted
- Pt starts from baseline pressure and is given a preset pressure boost on inspiration
- Vt is dependent on Pt Effort, Compliance and Resistance, and Preset Pressure Gradient
- Leaks and Sudden pressure spikes
- Useful in overcoming resistance of ETT
What occurs in BiPap
- Noninvasive BiLevel Support
- Pt triggers all breaths and rate can be set (Lowest is 4)
- Compensation for leaks-Estimated Vt and MV
- Prevents complications of intubation
- Pt and Therapist Dependent
What are the common modes of Closed Loop Ventilation?
Dual Control: Vol Delivered Every Breath
Dual Control Pressure Ventilation with Vt Target
What occurs in Dual Control: Vol Delivered Every Breath?
- Pt triggered, Pressure and Vol Targeted, Flow Cycled
- Vent monitors Vt and adjusts flow to meet minimum Vt
- Pt must be able to trigger breath and maintain adequate alveolar ventilation
- Breath terminated when flow reaches certain lvl, as long as Vt delivered
What Occurs in Dual Control Pressure Ventilation with Vt Target?
- Auto-Flow or PRVC
- Vent adjusts pressure breath by breath to reach desired Vt
- Adjust up or down depending on pt needs
- Allows for lower peak airway pressures as compliance improves
- Not ideal for pts with marked dyssynchrony
- Volume Support (VS)
- Similar to PS but pressure adjusts to deliver Vt target
What are the less frequently used Closed Loop Modes of Ventilation?
MMV
APRV
PAV
What occurs in MMV?
Mandatory Minute Ventilation
- PS mode with a Low MV threshold
- Reverts to VC if pt does not maintain MV
- Vent only monitors the vol over one min but cannot tell how it was achieved
