pilbeams ch 5

Question 1

About 75% of patients receiving invasive PPV are intubated

Answer 1

95% with an oral ET and 5% with a nasal ET. Tracheostomy tubes are used in the remaining 25% of patients receiving invasive PPV.

Question 2

There are two methods of providing noninvasive positive pressure ventilator support

Answer 2

• Continuous positive airway pressure (CPAP) • Noninvasive positive pressure ventilation (NIV)

Question 3

, CPAP and NIV are most commonly administered

Answer 3

via a face or nasal mask. Ensuring that the mask fits properly will minimize patient discomfort and help prevent air leaks.

Question 4

Patients with COPD often have trouble generating the pressure difference between the alveoli and the mouth to begin inspiratory gas flow.

Answer 4

The air trapped in the lungs creates a positive alveolar pressure. If the pressure in the lungs is positive at end exhalation, the pressure must drop below the pressure at the mouth to start gas flow into the lungs for inspiration.

Question 5

Externally applied CPAP can help overcome the

Answer 5

pressure difference between the mouth and the alveoli when flow limitation is the cause of auto-peep. The patient then does not have to work as hard to drop their alveolar pressure. CPAP can decrease inspiratory work.

Question 6

NIPPV/CPAP Candidates

Answer 6

Impending respiratory failure
OSA
COPD patients
Neuromuscular weakness
Chest wall deformities
Cardiogenic pulmonary edema
Post extubation difficulties
Asthma
Post –Op complications
Pneumonia
* Can reduce the need for mechanical ventilation in 60-75% of these cases

Question 7

In which of the following situations would NIV be tried?
1 Patient in whom blood pressure is 65/35, heart rate is 150 beats/min, and respiratory frequency is 34 breaths/min
2 Patient who nearly drowned who has copious amounts of white, frothy secretions
3 Patient with chronic obstructive pulmonary disease (COPD) and right lower-lobe pneumonia with respiratory acidosis and increased work of breathing (WOB)
4 A 5-year-old child who has aspirated a piece of chicken and is having trouble breathing

Answer 7

3 Patient with chronic obstructive pulmonary disease (COPD) and right lower-lobe pneumonia with respiratory acidosis and increased work of breathing (WOB)

Question 8

A high percentage of patients who need mechanical ventilation

Answer 8

require invasive positive pressure ventilation via an artificial airway.

Question 9

Full ventilatory support (FVS)

Answer 9

Ventilator provides all the energy necessary to maintain effective alveolar ventilation
Rates > 8 breaths/min
Adequate VT for patient 
Preset volume or pressure 
Allows patient to rest and recover

Question 10

Partial ventilatory support (PVS)

Answer 10

Patient participates in the work of breathing (WOB)
Rates < 6 breaths/min
Avoid if pt has increased WOB

Question 11

2 types of Targeted control variables

Answer 11

Volume

Pressure

Question 12

3 types of Timing of breath delivery

Answer 12

Continuous mandatory ventilation (CMV)
Intermittent mandatory ventilation (IMV)
Continuous spontaneous ventilation (CSV)

Question 13

Mandatory breath

Answer 13

Ventilator controls: timing, tidal volume or inspiratory pressure

Question 14

Spontaneous breath

Answer 14

Patient controls: the timing and the tidal volume

Volume and/or Pressure is based on patient demand and the patient’s lung characteristics

Question 15

Assisted breath

Answer 15

Has characteristics of both mandatory and spontaneous

All or part of the breath is generated by the ventilator, which does part of the WOB for the patient

Question 16

A patient receives a breath that is patient triggered, volume targeted, and time cycled. What type of breath is it?

Answer 16

Assisted

It is a patient controlled machine breath. The Vt is delivered by the ventilator and the ventilator cycles the breath.

Question 17

Targeting Volume as the Control Variable

Answer 17

Volume is constant, pressure based on patient’s lung characteristics
Advantages
Guarantees a specific volume delivery and volume of expired gas
The goal of volume-controlled ventilation is to maintain a certain PaCO2
Disadvantages
Evident when lung condition worsens
High pressures
Flow and sensitivity settings
Watch for patient-ventilator asynchrony if volume/flow isn’t adequate

Question 18

Targeting Pressure as the Control Variable

Answer 18

Pressure is set as the independent variable
Volume delivery changes as lung characteristics change, therefore volume delivery must be closely monitored
Considered a lung protective strategy
May be more comfortable for the spontaneously breathing patient

Question 19

Advantages and Disadvantages of Pressure-Controlled Ventilation

Answer 19

Advantages
Allows a set max pressure
Set pressure reduces the risk of overdistention
Decelerating flow pattern
Disadvantages
Volume delivery varies with the patient’s lung characteristics
Clinicians may be less familiar with pressure-control ventilation
VT and expired volume per minute (VE) decrease when lung characteristics deteriorate

Question 20

Pressure control ventilation and volume control ventilation are

Answer 20

are equally beneficial in patients who are not spontaneously breathing when a targeted flow pattern is used

Question 21

. In spontaneously breathing patients,

Answer 21

pressure-controlled ventilation may lower the WOB and improve patient comfort to a greater extent than volume-controlled ventilation, thereby reducing the need for sedatives and neuromuscular blocking agents.

Question 22

Continuous mandatory ventilation (CMV)

Answer 22

Time- or patient-triggered

Question 23

Intermittent mechanical ventilation (IMV)

Answer 23

Patient receives a set number of mandatory breaths

Can breath spontaneously breaths between mandatory breaths

Question 24

Continuous spontaneous ventilation (CSV)

Answer 24

All breaths are spontaneous

Patient-triggered

Question 25

CMV-All breaths are mandatory

Answer 25

and can be volume or pressure targeted. Breaths can be time triggered or patient triggered

Question 26

When breaths are time triggered,

Answer 26

they are described as controlled ventilation

Question 27

When breaths are patient triggered

Answer 27

they are described as assisted ventilation.

Question 28

Volume-targeted CMV (also called volume-controlled continuous mandatory ventilation [VC-CMV])

Answer 28

All breaths are mandatory
If patient triggered, it is called assisted
Once thought to minimize the WOB during mechanical ventilation
However, studies have shown that patients receiving this mode of ventilation may actually perform 33% to 50% or more of the work of inspiration
Pg. 66, Fig 5-4
This is true when inspiration is active and the set flow does not match the patient’s inspiratory flow demand. If the pressure does not rise smoothly and rapidly to peak during inspiration, flow is inadequate.

Question 29

Pressure-targeted CMV is also called pressure-control continuous mandatory ventilation (PC-CMV) or simply pressure-control ventilation (PCV)

Answer 29

All breaths are time or patient triggered, pressure targeted, and time cycled
The ventilator provides a constant pressure to the patient during inspiration

Question 30

PC-CMV

Answer 30

The operator sets:
the length of inspiration, the pressure level, and the backup rate of ventilation
The VT delivered by the ventilator is influenced by the compliance and resistance of the patient’s lungs, patient effort, and the set pressure
Several studies have shown that the decelerating ramp flow curve may improve gas distribution and allows the patient to vary inspiratory gas flow during spontaneous breathing efforts

Question 31

A patient on PC-CMV has widely fluctuating changes in Raw because of secretions and bronchospasm. The low tidal volume alarm is activated every few hours; the set pressure is 18 cm H2O. The physician is concerned about consistency in ventilation. What would you recommend? 
A. Increase the set pressure
 B. Sedate the patient 
C. Switch to VC-CMV 
D. Switch to PSV

Answer 31

C. Switch to VC-CMV

Question 32

VC-IMV and PC-IMV

Answer 32

Involves periodic volume- or pressure-targeted breaths that occur at set intervals (time triggering)
The patient can breathe spontaneously between mandatory (i.e., machine) breaths at the desired baseline pressure without receiving a mandatory breath
Most ventilators can also provide pressure support for spontaneous breaths

Question 33

Spontaneous breathing

Answer 33

Patients can breathe spontaneously through a ventilator circuit without receiving any mandatory breaths (T-piece

Question 34

Continuous positive airway pressure (CPAP)

Answer 34

Helpful for improving oxygenation in patients with refractory hypoxemia and a low FRC

Question 35

Pressure support ventilation (PSV)

Answer 35

The ventilator provides a constant pressure during inspiration once it senses that the patient has made an inspiratory effort

Question 36

Additional PSV Settings

Answer 36

Important that the ventilator deliver an appropriate flow at the beginning of inspiration
Current ICU ventilators allow the operator to adjust the slope of the pressure and flow curves during inspiration
Flow acceleration percent, inspiratory rise time, inspiratory rise time percent, and slope adjustment
Inspiratory cycle percent, inspiratory flow termination, and expiratory flow sensitivity
Rise Time-refers to the time required for the ventilator to rise to the set pressure at the beginning of inspiration

Question 37

In which of these four circumstances is it appropriate to select PSV?
1 As a method of weaning
2 To overcome the WOB through the endotracheal tube and circuit
3 For patients on PSV using the SIMV mode
4 For long-term patient support
1, 2, and 3
2, 3, and 4
1, 3, and 4
1, 2, 3, and 4

Answer 37

1, 2, 3, and 4

1 As a method of weaning
2 To overcome the WOB through the endotracheal tube and circuit
3 For patients on PSV using the SIMV mode
4 For long-term patient support

Question 38

Pressure augmentation

Answer 38

Dual-control mode that provides pressure-limited ventilation with volume delivery targeted for every breath
Patient triggered, pressure targeted breath, but targets the set volume
Will deliver additional flow if needed
Another term is volume-assured pressure support (VAPS)

Question 39

Pressure-regulated volume control

Answer 39

Volume-targeted, pressure control breath

Question 40

Volume-support ventilation

Answer 40

Basically pressure support with a volume target

No backup rate

Question 41

A patient with severe tetanus needs ventilatory support. Which of the following modes would you recommend?
A. Paralyze and sedate the patient; control ventilation using volume control (VC-CMV)
B. PC-CMV
C. VC-IMV
D. PSV with CPAP.

Answer 41

A. Paralyze and sedate the patient; control ventilation using volume control (VC-CMV)

Question 42

Airway Pressure-Release Ventilation (APRV)

Answer 42

Designed to provide two levels of CPAP and to allow spontaneous breathing at both levels when spontaneous effort is present
High CPAP level is interrupted intermittently to allow pressures to drop very briefly
Expiratory flow generally is not permitted to return to baseline (zero); therefore auto-PEEP is intentionally present
Both pressure levels are time triggered and time cycled

Question 43

Proportional Assist Ventilation (PAV)

Answer 43

Pressure, flow, and volume delivery are proportional to the patient’s spontaneous effort
Amount of pressure the ventilator produces depends on two factors:
1 the amount of inspiratory flow and volume demanded by the patient’s effort
2 the degree of amplification selected by the clinician (which determines the extent of ventilator response to patient effort)
PAV is a positive feedback system

Question 44

Which of the following modes would be used for a trauma victim with crushed chest injuries?
1 Negative-pressure ventilation
2 Pressure-cycled ventilator
3 Volume controlled–continuous mandatory ventilation (VC-CMV)
4 NIV

Answer 44

3 Volume controlled–continuous mandatory ventilation (VC-CMV)