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Mandatory Breath
- Ventilator does all WOB
- Triggered, Controlled (limited), cycled
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Assisted Breath
Started by patient & controlled (limited) & ended by ventilator.
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Spontaneous Breath
- Started, controlled & ended by patient
- Volume & pressure delivered based on patient demand & not by pre-selected amount set on vent.
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Pressure cycled inspiration
Ends when preset pressure is reached.
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Volume cycled inspiration
Ends preset volume delivered
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Time cycled inspiration
Ends when preset time met
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Flow cycled inspiration
Ends flow decrease to preset level
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Manual cycled
Patient or operator stops inspiration
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Negative pressure ventilation (extra thoracic)
- Vent controlled adjusting length inspiration (time cycled) & amount suction
- Home care, pts. neuromuscular
- Iron lung, chest cuirass
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Volume Cycled
- Pressure applied to airways until preset volume delivered
- Min volume constant, airway pressures increases or decrease changes pt compliance & airway resistance
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Pressure Cycled
- Positive pressure to airways until preset pressure reached.
- Tidal volume adjusted increasing or decreasing pressure limit
- Peak pressure constant, volume change lung compliance & airway resistance
- IPPB, continuous vent pts normal lungs
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Time Cycled
- Positive pressure until preset time reached
- PIP limited by adjustable pop off valve
- Tidal volume increasing or decreasing PIP, insp time, flow
- Infant vent
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Change Ventilator circuits
- Circuit grossly contaminated
- Malfuctioning
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High Pressure Limit Alarm
10 above peak airway pressure
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Minimum Exhaled Volume Alarm
100 below exhaled tidal volume
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Low Pressure Limit Alarm
10 below peak airway pressure
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Oxygen Alarm
5 above & below set FiO2
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Troubleshooting Low pressure Alarm
- Patient disconnect
- Leak ventilator circuit
- Insufficient flow
- Endotracheal/Trach tube cuff leak
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Troubleshooting High Pressure Alarm
- Patient obstruction (ET tube, pnuemothorax) increase Raw secretions
- Equipment (vent circuit)
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Troubleshooting Low Exhaled Volume Alarm
- Patient disconnect (vent circuit)
- Low spontaneous tidal volume.
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Initial Settings Infants
PIP
RR
PEEP
- PIP 20-30 cmH2O
- RR 20-30 bpm
- PEEP +2-+4 Max 8
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Indications for Mechanical Ventilation
- Apnea
- Acute Ventilatory Failure
- Impending vent failure-rising PaCO2Oxygenation
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Initial Settings Mechanical Vent
Vent Mode ___,____,____,_____
VT
RR
FiO2
PEEP
- Vent Mode: Control, A/C, IMV, SIMV
- VT 8-12 (pick lowest)
- RR 8-12
- FiO2 40-60%
- PEEP 0-10
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Ideal Body Weight Equation
- Male: 106+6 over 5 ft
- Female: 105+5 over 5 ft
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Exhaled Tidal Volume Equation
Vt= VE /f
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Minute Ventilation Equation
Vt X f
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Alveolar Minute Ventilation Equation
VA= (Vt-VD) X f
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Static Compliance Equation
- Exhaled Volume
- Pplat-PEEP
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Dynamic Compliance Equation
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Increasing Airway Resistance (Raw) on mechanical ventilator
- Peak inspiratory pressure (PIP) increases
- Plateau pressure (Ppl) remains same
- Raw can be estimated (PIP-Ppl)
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Common Causes for increasing Raw
- Secretions in airway
- Bronchospasm
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Treatment for increasing airway resistance
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Decreasing lung Compliance (CL) on mechanical ventilator
- Peak inspiratory pressure (PIP) increases
- Plateau pressure (Ppl) increases
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Common causes for decreasing lung compliance
- Atelectasis
- Pulmonary Edema
- ARDS
- Pneumonia
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Treatment for decreasing lung compliance
- Increase PEEP
- Treat underlying cause
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What is mean airway pressure (Paw)
Average pressure transmitted to airway from start breath to beginning of next.
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Assist Mode
- Patient initiates breath
- During IPPB
- NOT continuous ventialtion
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Control Mode
- Vent initiated breath at set rate
- NOT patient initiated
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Assist/Control Mode
- Patient Set RR
- Vent keeps certain rate
- Vent controls tidal volume for every breath
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SIMV Mode
- Patient spont breath
- Vent gives minimum minute vent
- Weaning
- COPD to normalize ABG
- Used instead of A/C reduce barotrauma
- Used w/ PEEP to reduce barotrauma
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Pressure Control Ventilation (PCV)
- Pressure Controlled Breaths
- ARDS
- Combined Inverse Ratio
- Used for
- Pts high FiO2 >60%, PEEP >15
- High PIP >50
- Low PaO2 & decrease compliance (ARDS)
- Exhaled Vt varies, adjust IT or PIP
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Inverse Ratio Ventilation (IRV)
- Pressure or volume controlled breaths
- Decreases PIP & PEEP
- Used
- PIP >50
- High FiO2 >60%, PEEP >15
- Low PaO2 & decreased compliance
- Pts should be paralyzed (Pavulon) & sedated (versed) b/c inverse ratio is uncomfortable & difficult to tolerate
- Start I:E Ratio 2:1 or greater
- Treat: ARDS
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Airway Pressure Release Ventilation (APRV)
- Spont Breath at positive pressure level
- Uses lower PIP = lower mean airway pressure
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Primary Controls for High Frequency Ventilation
- Rate control/frequency
- Amplitude/drive pressure regulator (volume)
- % inspiratory time (I:E ratio)
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Normalize High PaCO2
- Deceases or remove deadspace
- Increase tidal volume
- Increase respiratory rate
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Normalize a low PaCO2
- Increase deadspace
- Decrease respiratory rate
- Decrease tidal volume
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Increase low PaO2
- First: increase FiO2 by 5-10% (up to 60%)
- Then: increases PEEP levels by 2-5 cmH2O
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Decrease High PaO2
- First: decrease FiO2 to less than 0.60
- Then: decrease PEEP
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Expiratory Retard
- Similar to purse lip breathing
- Slows exhalation
- Decreases FRC
- Used for pts with COPD prevent airway collapse
- Does not change I:E Ratio or lengthen exp time.
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Adjust Inspiratory Plateau (Inflation Hold)
- Inspiration held at end of breath for short time (0-2 sec)
- Extends total inspiratory time, decreases time for exhalation, increases mean airway pressure.
- Increases diffusion gases & decreases microatelectasis
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Best position for patient on mechanical ventilator
- Initially placed in supine position.
- Low or semi fowlers used for later, best positions
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What Happens when PEEP/CPAP is high?
- PaO2 decreases
- Static compliance decreases
- Cardiac output/cardiac index decreases
- Hemodynamic pressure increase (PAP,PCWP)
- Decreased PVO2, SVO2
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How to calculate minimum flowrate
Flowrate: (tidal volume x Rate )X (I+E)
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Ventilator Protocols for ARDS
- Reduce Tidal volume to 6 ml/kg
- Keep plateau pressure <30
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Air trapping (auto PEEP) how to fix
- Increase inspiratory flow
- Increase expiratory time
- Decrease inspiratory time
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Assessment for Weaning
VT
VC
f
VE
MIP/NIF
MEP
RSBI
- VT >5
- VC >10
- f 8-20
- VE <10
- MIP/NIF >20
- MEP >40
- RSBI <100 (RR/VT)
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Clinical Measurements for weaning
Qs/Qt
VD/VT
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Decreasing Ventilator Settings
- First: decrease vent settings
- Use IMV/SIMV & turn down man rate
- O2 decreased FIO2 set below 60%
- Once 60% FiO2 reduce PEEP 2-5 at time
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Methods for weaning
T-piece trail/ traditional method, trial and error. Patient taken completely off vent
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Adverse conditions
- Increase HR >20
- Change BP 10-20
- Increases PaCO2 by >10
- RR increases by >10 or >30
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