Chapter 20; Discontinuation and Weaning from Mechanical Ventilation

Chapter 20; Discontinuation and Weaning from Mechanical Ventilation

 

Complete Chapter Questions With Answers

 

Sample Questions Are Posted Below

 

MULTIPLE CHOICE

 

1. 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:    pg. 403

 

2. 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	Set VT (mL)	Spontaneous VT (mL)	Set Rate (/min)	Spontaneous Rate  (/min)
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:    pg. 404| pg. 405

 

3. 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:    pg. 405

 

4. 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:    pg. 405

 

5. 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:    pg. 406