Critical Care Flashcards
How to calculate driving pressure
Tidal Volume / compliance
DP= Plateau pressure - PEEP
Goal <15
How to reduce driving pressure
Lower Tidal Volume
improve compliance (change peep)
POCUS: lung slide absent with B lines means…
Pneumonia
POCUS findings of pneumothorax
Absent lung slide
A lines
NO b lines
Lung point to confirm
What is set on APRV
Glorified CPAP with quick breaks to release CO2
- P high - 30-35
- P low (PEEP) - 0-5
- T high (inspiratory time) - usually 4- 8 sec
- T low (exp time) - usually 0.3-0.8sec
- FiO2
RR= # releases (ie 60sec/Thigh - Tlow)
What do you adjust on VV ECMO to change CO2 clearance
Sweep gas flow
What do you adjust on VV ECMO to change Oxygenation
oxygenator blood flow
Overall goal with vent when pt on VV ECMO?
Reduce FiO2 and vent pressures to achieve the most protective vent settings
Causes of low compliance on vent (ie increased PIP and plateau pressure)
Pulmonary:
- atelectasis
- Pulm edema
- Pneumothorax
- Hyperinflation
- Pulmonary fibrosis
Extra pulm:
- Abdominal distention
- Chest wall rigidity
- Main stem ETT
What causes high lung resistance on vent?
Increased PIP with normal Pplat
-Secretions
-Bronchospasm (asthma, COPD)
-Trouble with tube (biting, kinked, too small)
-Circuit filled with water
calculating Compliance
Compliance = TV/ (plateau pressure - PEEP)
How to assess for abdominal compartment syndrome
Bladder pressure
> 12 abnormal
Severe is >25
How to fix delayed cycle termination dyssynchrony?
Problem with pt exhaling while machine still giving insp support
Fix: Shorten set I time on vent
or switch to PS
or adjust sedation
What causes double triggering?
pt insp time > vent insp time
2 breath given w/o expiration b/c pt still inhaling and vent changes to exhalation
Leads to large TV (although might not appear so on monitor)
How to fix double triggering?
Fix with increasing I time or decreasing flow
What causes flow asynchronies?
Flow startvation
Pt trying to start another breath during vent supported inspiration because pt trying to get more flow
How to improve flow asynchronies?
increase flow
Switch to PS
What causes missed trigger asynchrony?
pt tries to take breath but effort does not trigger mechanical breath.
Causes:
- air trapping / intrinsic PEEP
- Triggering threshold too high
- Weak resp muscles
How to fix missed triggering asynchrony?
Increase sedation
Address autopeep
Decrease TV
decrease triggering threshold
change insp pressure/flow and cycling criteria
How to fix auto PEEP?
increase expiratory time (decrease rr, increase flow)
bronchodilators
increase intrinsic PEEP
What causes auto trigger asynchrony?
Air leak
breath initiated from external trigger before vol returns to zero
air leak –> decrease exhalation pressure
How to fix auto trigger asynchrony?
Fix leak
If cant (ie bronchopleural fistula) reduce the PEEP to zero so you dont get the auto trigger
How to use pulse pressure variation to assess volume responsiveness?
PPV proportional to stroke volume. greater variability in SV (increased PPV) more likely to be fluid responsive.
PPV>12% means if give fluids likely will have increased SV
3 conditions for using pulse pressure variation as assessment for volume responsiveness?
- Pt in sinus rhythm
- on MV w/o spontaneous resp and TV=8cc/kg
- NO open chest
also abd pressure <12
HR/RR ratio >3.6
What is pulsus pardoxus?
decrease in SBP >10 with respiration
suggests tamponade, severe asthma, COPD
Appearance of pulsus alternans on a-line?
alternating strong and weak pulses
iso low cardiac output shock states