18. High Frequency Jet Ventilation (HFJV) Flashcards
Life port ETT adapter:
What is measured at the pressure monitoring port? What function does the jet port serve?
PIP
used to inject inspired gas down the ETT in high velocity spurts
How is diffusion facilitated during inspiration?
train of tiny tidal volumes move high pO2 gas close to alveoli
How is evacuation of secretions facilitated on expiration?
expired gas swirls out around the inspired gas along the airway walls
List some considerations for HFV.
conventional ventilation upper limits reached (PIP > 20-30cmH2O, VT > 6mL/kg, rates > 55), air leak syndromes, pulmonary hypoplasia, non-homogenous lung disease (excessive secretions, MAS), abdominal distention/surgery, extreme prematurity, difficult to wean BDP, hemodynamic compromise
Jet PIP:
What is the primary control of ventilation? What produces the tidal volume?
delta P/tidal volume
delta P
What is jet rate usually started at? What should the rate be reduced to during air leak or evidence of air trapping?
420
240
What is inspiratory time set to? At a rate of 240, the I;E ratio is what and is advantageous for what?
- 02 sec
1: 12, advantageous for allowing healing of air leak
What is the role of the conventional ventilator?
provide fresh gas flow, provide PEEP, provide recruitment breaths
How is oxygenation controlled? What is the safest way to increase PEEP? At which FiO2 should MAP be weaned? When else should MAP be weaned?
MAP and FiO2
PEEP
< 30
any signs of over-distension or improving x-ray
What will you see with PEEP that is too low vs. too high?
too low: a/w collapse/atelectasis
too high: alveolar over distension, impedance of pulmonary perfusion, CV depression, poor right heart filling, impedance of venous return
HFJV PIP:
Where to start? When to raise? When to lower?
20-25cmH2O
when trying to decrease CO2, raise PIP as high as necessary
when trying to increase CO2, may need to raise PEEP to keep MAP constant
HFJV Rate:
Where to start? When to raise? When to lower?
420 bpm
to lower CO2
to increase CO2, lengthen exhalation time and reduce auto-PEEP or when weaning
HFJV Ti:
Where to start?
0.02 seconds and leave it
Why is HFJV successful in treating BPF?
high velocity gas shoots right past upper a/w leaks
What if you can’t oxygenate when you are attempting to facilitate healing by lowering all airway pressure?
increase PEEP
When does gas trapping occur? How is it confirmed? How can you lengthen exhalation time?
when tidal volumes have insufficient time to exit the lungs
CXR (hyperinflation), monitored PEEP exceeds CMV set PEEP
decrease jet rate
What does servo pressure = and when does it change? What can changes in servo pressure serve as?
automatically controlled driving pressure, changes as lung volume changes
give early warning of patients’ changing clinical conditions
What can the low alarm for Servo pressure go off?
degradation of lung mechanics, atelectasis, accumulation of secretions, tension pneumothorax, right mainstem intubation
When would the high alarm for Servo pressure go off?
improved lung mechanics (compliance or resistance), tubing leaks
If Servo pressure slowly falls over time, suction when:
What should you consider lung recruitment?
PaCO2 rises, SaO2 falls, chest wall movement diminishes
post suctioning or disconnects
What are the 2 options for weaning from the jet?
extubate to CPAP/NIV or switch to conventional (low rate, low pressures and then wean to extubate)
