Ch. 20 Weaning and Discontinuation from MV Flashcards
Box 20.8 Physical Signs and measurements of Increased WOB
- Use of Accessory Muscles
- Asynchronous breathing (chest wall diaphragm)
- Nasal flaring
- Diaphoresis
- Anxiety
- Tachypnea
- Substernal & Intercostal retraction
- Pt asynchronous w/ the vent
- Measured WOB >1.8 kg/m/min or 0.8 J/L
- Measured WOB greater than or equal to 15 of total O2 consumption
What is discontinuation of the vent
- the pt still has an airway but no longer getting support from the vent
What is extubation?
The removal of the airway
About ___% of pt requiring temporary MV, do not require weaning
80%
Define weaning
the gradual reduction of ventilatory support from a pt whose condition is improving
The decision to wean a pt from the ventilator depends on
the level of recovery from the medical problems that imposed the need for MV and the pt overall condition and psychological
What are the 3 common methods for weaning which are used to reduce ventilatory support and gradually place more of the WOB on the respiratory muscles?
- IMV
- PSV
- T-piece
What is a common weaning practice w/ IMV?
To reduce the mandatory rate progressively usually in steps of 1 or 2 breaths/min and at a pace that matches the pt’s improvement
What else can be added to IMV? (2)
PSV ( 5 to 10 cm H20)
PEEP (3 to 5 cm H20)
What does the pt control with PSV?
- RR
- timing
- depth of each breath
PSV is
- patient triggered
- pressure limited
- flow cycled
PSV allows the RT to adjust the
ventilatory workload for each spontaneous breath to enhance endurance conditioning of respiratory muscles w/o causing fatigue
When PSV is reduced to about 5 cm H20, the pressure level is not
high enough to contribute significantly to ventilatory support
The weaning process started when the pt was able to breathe spontaneously for brief periods w/o ventilatory support and the criteria for weaning had met
T- Piece Weaning
T-piece system includes
a heated humidifier w/ a large reservoir. The humidifier is connected to a blended gas source (at least 10 L/min of FiO2)
What is the humidified gas source connected to?
a T-piece (Briggs adapter) w/ large-bore tubing which is attached to the pt’s ET
Pt less like to tolerate T-piece weaning include (4)
- underlying heart disease
- severe muscle weakness
- pts who are inclined to panic b/c of psychological problems
- preexisting chronic lung conditions
What pt population will benefit from a trache
- pt who requires high levels of sedation to tolerate ETs
- pts w/ marginal respiratory mechanics and who may have tachypnea as a result
- pt’s who have lower resistance, may reduce the risk for muscle overload
- pt who may gain psychological benefits from the ability to eat, talk, and have greater mobility
- pts who increased mobility may aid physical therapy
- The most important beneficial outcome of a trache is the potential to facilitate discontinuation of mechanical ventilatory support
Box 20.13 Criteria for instituting NIV after failure to wean from invasive MV in extubated pts
- Resolution of problems leading to respiratory failure
- Ability to tolerate a spontaneous breathing trial for 10 to 15 min
- Strong cough reflex
- Hemodynamic stability
- Low FiO2 requirements
- Functioning gastrointestinal tract
- Optimum nutritional status
What are the measurements used to evaluate a pt’s ventilatory muscle function before weaning and extubation? (5)
- VC
- Ve
- RR
- Spontaneous Vt
- RSBI
The following three key points have evolved as criteria for weaning:
- The problem that caused the pt to require ventilation must be resolved
- Certain measurable criteria should be assessed to help establish a pt’s readiness for discontinuation
- An SBT should be performed to firmly establish readiness for weaning
What are examples of pts who need temporary vent support and who do not require a gradual weaning process that can be disconnected within a few hours or days? (3)
- Post-op, recovering from anesthesia
- Treatment of uncomplicated drug overdose
- Exacerbation of asthma
Vent support and artificial airway should be removed ASAP to avoid? (4)
- VAP
- airway trauma from ETT
- unnecessary sedation
- ventilatory- induced injury
Premature withdraw of vent support or airway can result in (4)
- Ventilatory muscle fatigue
- Compromised gas exchange
- Loss of airway protection
- High mortality rate
