Mechanical Ventilation Flashcards
early tracheostomy benefits?
lower sedation use, trend toward dec mortality. no decrease in risk of PNA or days on MV
mechanism of benefit with HHFNC?
higher Fio2, CPAP, turbulent not laminar flow which leads to gas mixing, decrease in anatomic dead space
Pressure Control mode sudden loss of tidal volume with reduced expiratory flow and prolonged expiratory time?
airway obstruction
DTF threshold for failure to liberate from MV?
<30%
things on vent that will worsen diaphragmatic dysfunction?
increased support, increased use of controlled modes
abdominal paradox
sign of diaphragmatic weakness within 1 minute of SBT
things that can cause phrenic nerve injruy during CABG?
ishcemia to vaso vasorum, direct trauma, cold induced neuropraxia
diaphragm paralysis on sniff test?
during forceful inspiration the paralyzed diapharagm will move upward
physiology of SILI?
more even distribution of pleural pressure changes to all lung units, harder diaphragm work
SILI can cause these problems?
overdistension of damaged lung areas, air trapping from inc RR, resp muscle fatigue of diaphragm, pendeluft
how is. a pressure support breath terminated?
flow cycled via a percentage of the peak inspiratory flow
surrogate for transpulmonary pressure in a normal person?
plateau pressure
in morbid obesity how does pplat inaccurately predict Tp?
low chest wall compliance leading to a high pleural pressure therefore the pplat will overestimate the Tp and underestimate the pressure needed to overcome this higher pleural pressure
how does heliox work?
lower density than oxygen making more linear distribution through airways in high resistance situation
when is heliox CI?
it is a 70/30 mixture so if patient is requiring high oxygen then should not use
dynamic complicane equation?
TV/(peak-PEEP)
static compliance equation?
TV/(plateau- PEEP)
increase in peak without rise in plateau?
mucus plug
plateau and peak in (mainstem intubation, TPTX, air trapping)
inc in plateau and peak
causes of decreased static compliance? inc in both pip and Plat
PTX, ARDS, effusion, restrictive disease
causes of decreased dynamic lung compliance? inc PIP without inc plat
tube occlusion, bronchial secretions, bronchospasm
most direct measurement of diaphragmatic failure in MV?
transdiaphragmatic pressure via nerve stimulation
reintubation can lead to what outcomes?
inc change of nosocomial PNa, inc in crude mrotality, inc LOS
disadvantages of Volume AC?
worse change for respiratory alkalosis
what will increadse minute ventilation in HFOV?>
decrease in the frequency
change in bias flow in HFOV does what?
changers oxygenation
PRVC you set what?
goal TV
in PAV what does the clinician set?
percent work of breathing
NAVA does what?
pressure is proportional to the electrical activity of the diaphragm
how do you measure the electrical activity in NAVA?
via esophageal probe
benefits of NAVA?
decreases innefectvie tirggering
decreases overinflation
improves neuro ventilation coupling
change O2 in HFOV?
change mean airway pressure, I time, and bias flow
change ventilation in HFOV?
higher frequency lower MV
higher delta pressure higher MV
why is there an increased mortality in HFOV?
increase mAP, leasding to decrease venous return
concave up
overdistension, stress index >1, compliance decreases over time
concave down
underrecruitment, stress index <1, complaicne increase with time
TPP at end expiration?
PEEP- esophageal pressure at end exp
negative value indicates repetitive collapse
TPP at end inspiration?
plateau- esophageal pressure at end insp
> 25 indicates overdistension
definition of the TPP?
pressure to overcome the lung recoil
esophageal pressure in obestiy and volume overload?
high
what is pendelluft?
caused by regional variation in ressitance and elastance
what is pendelluft?
caused by regional variation in ressitance and elastance
in pressure control when does plateau equal peak?
during zero flow
in spontaneously breathing patient, how would you measure autopeep
esophageal balloon
why would autopeep be underestimated in asthma?
not accounting for the closed airways during exhalation
a patient with marked respiratory distress spontaneous breathing, why is their TPP high?
very negative pleural pressure
static compliance equation.
VT/(plat-PEEP)
dynamic complaince eq
VT/(PIP-PEEP)
compliance of the chest wall?
VT/(change of esophageal pressure)
normal complaince of the respiratory system? Value
normal value 50-100 ml/cmH2O
normal chest wall compliance?
80 ml/cmH2O
lung compliance equation, normal?
VT/change in transpulmonary pressure
200 ml/cmH2O
elastance equation?
inverse of compliance
1/Crs= 1/compliance chest wall + 1/complaince of lung
resistance during inspiration equation?
(PIP-plat)/iflow
expiration plat-PEEP/eflow
work of breathing equation
pressure xvolume
how can you deteremine WOB?
difference of esophageal pressure at inspiration and expiration
hallmark presentation of inadeqaute flow?
sucking down on pressure curve
pressure curve is concave up?
inadeqate flow
how to fix inadequate flow?
inc flow, change to pressure setting and inc pressure setting
positive deflection in pressure curve ending?
delayed terimination
another clue to delayed termination?
prolonged period of zero flow
delayed termination fix?
shorten the cycle criteria
premature termination fix?
lengthen cycle criteria
difference between PEEP and iPEEP?
iPEEP is preferentially distrubtued to airways with obstructiona dn away from poorly compliant alveoli which is not beneficial
right mainstem intubation will lead to what?
worse compliance
high esophageal pressure at end expiration could signify what?
instrinsic PEEP
