Clin Med - Vent basics Flashcards
why intubate?
- airway protection
- difficulty oxygenating
- difficulty w/ respirations
what is a ventilator
- a simple machines: it delivers a volume of air at a specified pressure for a determined length of time at a prescribed rate
- it’s a bellows; you can squeeze faster, harder, deeper
Vt (or Tv)
tidal volume
MV
minute ventilation
FiO2
fraction of inspired oxygen
PEEP
positive end expiratory pressure
BPAP
bi-level positive airway pressure
CPAP
continuous positive airway pressure
SaO2/So2
a derived value of the arterial oxygen saturation; measures the percentage of hgb which is fully combine w/ oxygen
PO2
partial pressure of oxygen
PCO2
partial pressure of CO2
What to consider in ventilation?
The “Ts”
- trigger
- target
who triggers the vent?
- vent provider takes complete control
- if patient is able to breath on their own, they take control
modes of ventilation (3)
- AC (assist control)
- SIMV (synchronized intermittent mandatory ventilation)
- pressure support/pressure control
AC Ventilation
- provider/vent determines the rate for the patient
- does not sense pts efforts at all
- can lead to breath stacking
- can lead to respiratory alkalosis/acidosis
- can lead to lung injury/PTX
SIMV Ventilation
- control is shared by vent and pt
- provider/vent set the rate and minute ventilation and any pressure support
- vent sense pt by negative pressure or interruption of flow loop
- if pt breathes on their own b/w scheduled breaths, vent does nothing
- if pt breathes near an upcoming scheduled breath the vent applies continued pressure to reach a specified Tv
pressure controlled/ pressure support ventilation
- completely patient dependent
- provider/vent specify pressure
- vent triggers at beginning of breath and measures negative pressure
- if insufficient, vent provides background pressure to increase breath
- must set an apnea time
targets for ventilation
- for most pts, volume is best target
- A/C has volume control
- A/C and SIMV have pressure control
what is traditional volume set on ventilation?
- 8-12 cc/kg of IBW
- ARDSnet volume 4-8cc/kg
- measure plateau pressure goal is <30
peak pressure
- sum of lung stiffness, chest wall compliance and airway resistance
- goal is < 35
plateau pressure
- measured by holding during inspiratory phase
- reflects the pressure at the alveoli
What could high pressure alarms mean?
- machine (inappropriate settings, dysynchrony)
- circuit (kinking, mucus, wet filter)
- man (bronchospasm, decreased compliance, PTX, effusion, obesity, coughing)
What is the first thing to do if high pressure alarms go off?
-disconnect the pt from vent and resume bagging
How do you tell what the problem is?
-measure peak AND plateau pressures
if peak pressure is high, but plateau pressure is normal what should be considered?
-problem with resistance
if peak AND plateau pressure are high what should be considered?
-problem with compliance and lung restriction
volume mode
- a flow of air over a unit of time
- breath is terminated once the entire volume is inhaled
pressure mode
-breath terminates after a certain amount of time
review cases
start at slide 18
