Ch. 20 Test, Weaning Flashcards
All of the following patients are intubated and receiving mechanical ventilation. The patient most likely to require slow liberation from mechanical ventilation is which of the following?
a. A patient who overdosed on diazepam
b. A postoperative patient who had knee surgery
c. A patient with a severe exacerbation of asthma
d. A patient with chest contusions from an accident
ANS: D
A large percentage of patients who need temporary mechanical ventilation do not require a gradual withdrawal process. Such patients include those receiving postoperative ventilatory support for recovery from anesthesia, treatment of uncomplicated drug overdose, and exacerbation of asthma. The patient with chest contusions from an accident has a higher risk of developing problems that will require a more gradual weaning process.
DIF: 2 REF: p. 403
A patient is being weaned from invasive mechanical ventilation using VC-SIMV without pressure support. The respiratory therapist reviews the following data from the last few hours.
Time SetVT Spon VT Set Rate SponRate 0630 650 410 8 6 1020 650 400 6 10 1600 650 320 4 20 2200 650 250 2 32
What should the respiratory therapist recommend for this patient?
a. Switch the mode to VC-CMV.
b. Add and titrate pressure support.
c. Extubate and place the patient on NPPV.
d. Increase the set rate to 8 breaths/min.
ANS: B
The data demonstrate that as the set SIMV was decreased, the patient’s spontaneous respiratory rate increased and the spontaneous tidal volume decreased. This shows that the patient’s work of breathing is excessive and most likely due to the resistance from the ventilator system, circuit, and artificial airway. Initiate pressure support and titrate the level to improve the spontaneous volume and decrease the spontaneous rate. Once the patient is stable, the pressure support may be weaned.
DIF: 3 REF: p. 404, 405
What ends inspiration in pressure support ventilation?
a. Time
b. Flow
c. Volume
d. Pressure
ANS: B
Each pressure support breath is flow cycled.
DIF: 1 REF: p. 405
At what pressure is pressure support not high enough to contribute significantly to ventilatory support but is sufficient to overcome the work imposed by the ventilator system?
a. 2 cm H2O
b. 5 cm H2O
c. 8 cm H2O
d. 10 cm H2O
ANS: B
When pressure support is reduced to about 5 cm H2O, the pressure level is not high enough to contribute significantly to ventilatory support. However, this level of support usually is sufficient to overcome the work imposed by the ventilator system (i.e., the resistance of the ET tube, trigger sensitivity, demand-flow capabilities, and the type of humidifier used).
DIF: 1 REF: p. 405
Which mode of ventilation delivers the exact amount of pressure required to overcome the resistive load imposed by the ET tube for the flow measured at the time?
a. Automode
b. Volume-targeted PSV
c. Pressure support ventilation
d. Automatic tube compensation
ANS: D
ATC reduces the work of breathing associated with increased ET tube resistance. ATC is designed to deliver exactly the amount of pressure required to overcome the resistive load imposed by the ET tube for the flow measured at the time. In a sense, this is providing variable PSV with variable inspiratory flow compensation. Volume-targeted PSV maintains a target volume by varying the pressure support level. PSV provides an operator-selected set pressure for every spontaneous breath. The automode can switch between time-triggered mandatory breaths and patient-triggered, volume-targeted, pressure-limited breaths as long as the patient is breathing spontaneously.
DIF: 1 REF: p.406
The mode of ventilation that maintains a minimum VE by increasing or decreasing the amount of support (VT or respiratory rate) given to the patient is ___________________.
a. volume support
b. automatic tube compensation
c. mandatory minute ventilation
d. adaptive support ventilation
ANS: C
In MMV the ventilator automatically increases the level of support if the patient’s spontaneous ventilation decreases, thus maintaining a consistent minimum VE. Patients who regain the ability to breathe spontaneously can increase their own VE, and the machine automatically lowers support without the clinician having to change any specific ventilator settings.
DIF: 1 REF: p. 408
The closed loop mode used for weaning from mechanical ventilation is which of the following?
a. Pressure support ventilation
b. Adaptive support ventilation
c. Continuous positive airway pressure
d. Intermittent mandatory ventilation
ANS: B
ASV is a patient-centered method of closed loop mechanical ventilation that increases or decreases ventilatory support based on monitored patient parameters.
DIF: 1 REF: p. 408
A postoperative patient, still under anesthesia, is being ventilated with VC-CMV with Automode. After 2 hours the patient is waking up and beginning to breathe spontaneously. The ventilator will respond by _____________________.
a. switching to the pressure support mode.
b. switching to the volume support mode.
c. delivering time-triggered, pressure-limited breaths.
d. ensuring minimum mandatory minute ventilation.
ANS: B
If a postoperative patient is still recovering from the effects of anesthesia and the ventilator operator has selected volume-controlled continuous mandatory ventilation (VC-CMV) with Automode as the operating mode, all breaths are mandatory (time triggered, volume limited, and time cycled). If the patient begins to trigger breaths, the ventilator switches to VS (patient triggered, pressure limited, and flow cycled with a volume target) and remains in this mode as long as the patient is breathing spontaneously.
DIF: 1 REF: p. 407, 408
The ACCP/SCCM/AARC task force recommends that a search for all possible causes that may be contributing to ventilator dependence be undertaken in patients who require mechanical ventilation for longer than ______ hours.
a. 12
b. 24
c. 48
d. 72
ANS: B
This is the first recommendation for weaning a patient from mechanical ventilation established by the ACCP/SCCM/AARC task force.
DIF: 1 REF: p. 409
Assess the following data obtained from the spontaneous breathing trials of four patients. Which patient is most likely to be weaned successfully at this time?
a. Spontaneous rate = 32 breaths/min, VT = 375 mL, PaO2 = 98 mm Hg, FIO2 = 0.4
b. Spontaneous rate = 15 breaths/min, VT = 450 mL, PaO2 = 87 mm Hg, FIO2 = 0.6
c. Spontaneous rate = 15 breaths/min, VT = 650 mL, PaO2 = 91 mm Hg, FIO2 = 0.28
d. Spontaneous rate = 12 breaths/min, VT = 680 mL, PaO2 = 79 mm Hg, FIO2 = 0.5
ANS: C
Calculate the f/VT and PaO2/FIO2 for each patient. The patient with acceptable criteria has an f/VT of 23 and a PaO2/FIO2 of 325.
DIF: 2 REF: p. 409-413, Table 20-1
A 46-year-old male patient (IBW = 85 kg) who was injured in a motor vehicle accident has been receiving invasive mechanical ventilation for 24 hours. The patient is awake and alert and looks comfortable on these settings: VC-SIMV with pressure support of 5 cm H2O; set rate = 8 breaths/min; set VT = 500 mL; FIO2 = 0.4; PEEP = 5 cm H2O. A 10-minute spontaneous breathing trial (SBT) yields this information: f = 30 breaths/min, RSBI = 145, P0.1 = 10 cm H2O. What should the respiratory therapist suggest to the physician during patient rounds?
a. Sedate the patient and place him on VC-CMV.
b. Continue with the current ventilator settings.
c. Switch to PC-CMV with a rate of 14 breaths/min.
d. Decrease the mandatory SIMV rate to 4 breaths/min.
ANS: B
The RSBI is at a level that suggests the patient is not ready for weaning. An RSBI below 105 suggests that weaning is likely to be successful. The P0.1 is a measurement of the drive to breathe. The patient achieved 10 cm H2O, which indicates a high drive to breathe and suggests that weaning from mechanical ventilation is not likely to succeed. This information is a strong indicator that the patient should not begin active weaning at this time and should be continued on the original settings, because the patient was comfortable on those settings.
DIF: 3 REF: p. 409-413
Calculate and determine the weanability of patients with this data: CD = 25 mL/cm H2O, PImax = -28 cm H2O, PaO2 = 93 mm Hg, PAO2 = 158 mm Hg, and f = 22 breaths/min.
a. 2—not weanable
b. 19—weanable
c. 32—not weanable
d. 54—weanable
ANS: B
Use the CROP formula: CROP (CD PImax [PaO2/PAO2])/f.
DIF: 2 REF: p. 413
Which parameter is used as the primary index of the drive to breathe?
a. Airway occlusion pressure
b. CROP index
c. Maximum inspiratory pressure
d. Rapid shallow breathing index
ANS: A
The inspiratory drive to breathe is established by measuring the airway occlusion pressure (P0.1 [or P100]).
DIF: 1 REF: p. 412
An SBT should not continue for longer than _____ minutes.
a. 30
b. 60
c. 120
d. 180
ANS: C
SBTs typically last at least 30 minutes but no longer than 120 minutes.
DIF: 1 REF: p. 413
In which patient would continued use of an artificial airway be necessary?
a. A patient with upper airway burns and no peritubular leak
b. A patient who tests positive for a peritubular leak
c. A patient with bronchospasm and supplemental oxygen requirements
d. A patient with a strong cough who expectorates moderate amounts of sputum
ANS: A
A patient with upper airway burns may have upper airway inflammation that could obstruct the upper airways. The fact that the patient does not have a peritubular leak means that the airway caliber is not adequate. Extubation of this patient at this time would not be successful.
DIF: 2 REF: p. 414
