Factors that affect NML expiratory gas flow
- elastic recoil (+2) and intrathoracic (+3)
- total pressure at alveolus (+5) > than that at mouth so air moves out of lung
- some pressure (-1) is lost to Raw
- intraluminal pressure is +5 -1 = +4
Factors that affect ABNML expiratory gas flow
- aging and emphysema decrease elastic recoil to (+1). total exp (+4) not (+5)
- more pressure is lost to Raw (-2)
- intraluminal pressure is (+2)
- because intrathoracic pressure of +3 is greater than intraluminal pressure, the airway collapses
- pursed-lip breathing increases intraluminal press
Expiratory gas flow
- ON vent, no pursed-lip breathing
- expiratory retard used - not available now
- low level of PEEP may help
What do post surgery patients develop?
- atelectasis
- shunting
- decreased PaO2
- reduced compliance with ventilation
What kind of breaths reduce atelectasis, shunting, and decreased PaO2 and compliance?
sigh
What causes a decreased in compliance and PaO2?
- loss of FRC in the supine position
- may be improved by PEEP
What kind of patients want sigh breaths and why?
paralyzed patients want sigh breaths to feel like they’re getting giant breaths
What is the suggested time to give sigh breaths?
3-4 times per hour (once every 10 minutes)
How much VT do sigh breaths give?
1 and 1/2 times tidal breath
Other studies found that what reduced atelectasis?
large tidal breaths
Some other studies found that atelectasis is common with what mode and what may be helpful?
PSV; sigh breaths
Not indicated is ___ for hypoxemia
CPAP
Sensitivity
- patient should be able to easily flow or pressure trigger a breath
- watch for auto-PEEP
- watch to see if accessory muscle use decreases
Settings for sensitivity
- flow 1-10 L
- pressure -1 to -2 cmH2O
- watch for auto-PEEP (do an expiratory hold)
How should you increase PEEP?
until PIP rises
In pressure control, what determines the tidal volume?
driving pressure
You want to make sure you don’t change the driving pressure when making ___ changes?
PEEP
A patient with COPD is receiving PSV and seems to be having difficulty triggering the vent even though you have it set at -1 cmH2O. What must be causing this problem and can you do anything to correct it?
- it could be auto-PEEP (do an expiratory hold to see)
- make peep match auto-PEEP
- to get rid of auto-PEEP, decrease rate and increase VT
Selection of FiO2?
- arterial tension between 60-100 mmHg
- jf had ABG place on same oxygen
- no ABG place 100% to restore oxygenation
- no need to worry about hypoxic drive if vent MV is meeting patient’s needs
- get ABG within 15-30 mins and adjust
What kind of patients is SpO2 not accurate in?
- smoke inhalation patients
- someone with met hemoglobin
- hypothermia patients
- carbon monoxide poisoning patients
- patients who smoke
If FiO2 required is greater than 0.50 what should you consider?
PEEP
Humidification
- need to provide 30 mgs H2O/L of absolute humidity at a range of about 31-35 for flows up to VE of 20-30 L/min
- Nml 100%
What HME exceptions are noted?
- thick, copious or bloody secretions
- VT < 70% of inhaled VT
- body temp 10L/min
- with aerosolized medication
Nebulization
- should not add VT or change FiO2
- should not change alarm function
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Classifications of Ventilators36
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How A Breath is Delivered53
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Lab Modes Quiz6
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Modes16
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Needs73
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Effects of Positive Pressure Ventilation55
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Initial Ventilator Settings79
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Written Lab Final94
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Final Consideration36
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Basic Patient Assessment46
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Introduction to Ventilator Graphics24
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Troubleshooting36
