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What is ventilation?
Ability to move air in and out of lungs.
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What is Respiration?
Gas exchange at the cellular level. o2 in and co2.
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Reasons for ventilation support:
- Acute ventiatory failure
- -acute respiratory acidosis
- -increased CO2
- -decrease pH
- Hypoxemia-shunting
- -cannot get O2across membrane
- Pulmonary mechanics
- -Obstruction
- -decrease compliance
- Other
- -neuro, diaphragm paralysis
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Post intubation
- Secure ET tube
- document placement
- Ausculate bialteally
- End tidal CO2-measures co2 exhaled through breath-assures that gas exchange is taking place
- always do an xray
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Tracheostomy
- Used for prolonged need for ventilation and artificial airway
- Usually if needed for more than 2-3 weeks
- Can improve weaning
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Negative pressure ventilation
- We all have negative pressure to suck air in.
- Diaphram moves down and lungs expand causing negative pressure
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Positive Pressure Ventilation
- Pushing air in.
- Volume cycled delivers a present volume of air to lungs -This is the most common mode
- Pressure cycled-delivers a preset gas pressure
- Time cycled - preset inspiration time
- Flow cycled- pressure augmentation during insp, decreases work of breathing.
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Tidal Volume
- Amount of air delivered to the lungs in one breath.
- Normal TV = 5-12ml/kg (500-800ml)
- Complications of high TV-Barotrauma - gross damage to alveolar
- Consider lung compliane- avoid high volume
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Fracion of inspired Oyxgen (FIO2)
- Percentage of Oxygen of inspired gas
- Range 0.21-1.0(21%-100%)
- Use the lowest possible level to avoid oxygen toxicity
- Oxygen Toxicity-damages endothelial lining-decreases mucous and surfactant protection -COPD patient
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Rate
- Number of breaths /minutes delivered to patient
- Normal range = 6-20 individualized per pateint
- In some ventilator modes, can be controlled by patient
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PEEP
Positive End Expiratory Pressure
- Keeps alveoli inflated during expiration
- Physiologic Peep 3-5 cm H2O
- Primary use: Refractory hypoxemia-prevents atelectasis
- Auto PEEP - building of pressure leading to air trapping
- Complications : Barotrauma, decreased CO
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Peak Airway Pressure
(Peak Inspiratory Pressure)
- Pressure required to deliver volume of air
- Healthy lungs =20cm H2O
- Goal <40cm
- Increased ->decreasing lung compliance -worsening pulmonary status (ARDS)-coughing, and need for suctioning
- Decreased = improving status
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Ventilation Modes
- Assist control (AC)
- Synchronous Intermittent Mandatory Ventilation (SIMV)
- Continuous Positive Airway Pressure (CPAP)
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Assist control
Continuous Mandatory ventilation
- Pateint gets set number of guaranteed breaths/min at a set TV
- Additional inspiratory breaths are assisted at set TV
- Advantages-allows resp muscles to rest
- Disadvantages - High rsp rates will cause hyperventilation-become alkalosis (blowing off too much co2
- Assists the patient is pt tries to breath but if pt does not breath then the machine will breath for him.
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Synchronous Intermettent mandatory Ventilation (SIMV)
- Patient get set number of guaranteed breaths/min at set TV
- Pt sets own TV and will only get what they can breath on their own
- Advantages-forces exerciser of resp muscles
- Disadvantages -potential for fatique
- Used for weaning-will decrease breaths per minute to make patient want to breath
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Continuous Positive Airway (CPAP)
- No tidal volume or resp rate
- Patient generates their own resp rate and TV
- Used as a weaning mode
- Often used in conjunction with psv
- Patient is breathing on their own- this is just a source of O2
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Pressure Support Ventilation (PSV)
- Overcomes increased airway resistance
- Assists with weaning
- Decreases work of breathing
- Triggered by spontaneous breath
- 5-15cmH2O
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High Pressure
- Indicates resistance in circut
- Secretions
- coughing
- tube kinked or patient biting on tube
- High lung compliance
- poor synchronization
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Low Pressure
- indicates a disconnection or leak in system
- Check patient tubing and connections
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Major complications of Mechanical Ventilation
- Cardiovascular- decreased CO, preload, sv
- Air in chest cavity causes heart not able to expand
- Pulmonary - changes flow of gas, oxygen, toxicity, risk of VAP, barotrauma
- Renal- decreased perfusion
- GI - Stress Ulcer
- Neurovascular- decreased flow to head, venous return from head (Increase ICP)
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Oxygen Toxicity
- 80%FiO2 for 48 hours or longer
- Damages endothelium
- Nonspecific symptoms
- Use minimum oxygen level to obtain acceptable paco2
- Peep increases gas exchange so o2% can be decreased-so adding peep helps prevent Oxygen toxicity
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Ventilator Bundle
- A group of interventions designed to prevent complications of mechanical ventilation
- head of bed elevate 30
- prevention of stress ulcers - PPI (Protonixs)
- DVT Prophylaxis (Heparin, compression stockings)
- Sedation vactions (wake once a day to check neuro)
- Oral care q4hrs- reduces bacteria load in the mouth
- Consider weaning trial-assess ability to wean daily
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Ineffective Airway Clearance
- Lose effective cough
- suction only when needed -hyperoxygenate- suction and reassess- return patient to vent
- Inline suctioning is used
- Suction for 5-10 seconds max
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Weaning
- Assess Readiness to Wean (RTW)
- All patient parameters must be optimized
- FIO2 <50%
- PEEP<5
- Nutriton optimized
- Afebrile
- NO GI bleed-stable H&H
- Stable hemodynamics-adequate bp
- Mental status-good level of conciousness
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Weaning Modes -
CPAP Weaning
- Patient remains attached to ventilator
- ventilator provides oxygenated air
- Patient does all the work of breathing
- May have psv added
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Weaning Mode
IMV
- Patient starts off with high number of guaranteed breaths
- Over time guaranteed breaths are reduced, forcing patient to do more work of breathing
- builds endurance of resp muscles
- Often used with difficult wean patients.
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Signs that they are not tolerating wean:
- increase BP
- increase HR
- increase CO2
- decrease pulse ox
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