Respiratory Monitoring in Critical Care

MULTIPLE CHOICE

     1.   All the following activities are included in respiratory monitoring except:

a.
alarm setting.
b.
pulmonary consults.
c.
physical examinations.
d.
measurements and calculations.

ANS:  B

These goals are accomplished through the use of physical examination, monitoring equipment, measurements, calculations, and alarms.

REF:   pg. 315           OBJ:   1

     2.   It is important to monitor ventilatory parameters in addition to arterial blood gases because:

a.
it is easier and more cost-effective to monitor ventilatory parameters.
b.
changes in ventilatory parameters will occur before they are seen in arterial blood gases.
c.
monitoring of ventilatory parameters does not require specialized equipment and can be done more quickly.
d.
monitoring of ventilatory parameters can be done without a physician’s order, whereas arterial blood gas monitoring requires a physician’s order.

ANS:  B

Changes in the patient’s metabolism, lung mechanics, ventilatory efficiency, and equipment function will occur before changes in blood gases are seen.

REF:   pg. 315           OBJ:   1

     3.   Ventilatory measurements routinely monitored at the bedside include all of the following except:

a.
airway pressures.
b.
lung volumes and flows.
c.
fractional gas concentrations.
d.
oxygen consumption and carbon dioxide production.

ANS:  D

Ventilatory measurements that can be monitored at the bedside in the intensive care unit (ICU) routinely include lung volumes and flows, airway pressures, and fractional gas concentrations.

REF:   pg. 315           OBJ:   1

     4.   It is important to monitor lung volumes in ICU patients because changes in lung volumes reflect all of the following changes except:

a.
changes in gas exchange in the lung.
b.
changes in the patient’s clinical status.
c.
a response to therapy and any problems that may arise.
d.
they influence the selection of antibiotic therapy in the ICU.

ANS:  D

Lung volumes are important to the clinician for four reasons: (1) they affect gas exchange in the lung; (2) they reflect changes (improvement of deterioration) in the patient’s clinical status; (3) they indicate the response to therapy; and (4) they signal problems with patient/ventilator interface (i.e., circuitry, ventilator settings).

REF:   pg. 316           OBJ:   1

     5.   A nonintubated patient should be monitored for lung volumes in the presence of the following clinical conditions except:

a.
deteriorating blood gases.
b.
receipt of noninvasive positive-pressure ventilation.
c.
respiratory rate less than 30 breaths/min.
d.
central nervous system depression.

ANS:  C

All the following represent conditions associated with the need for monitoring lung volumes in nonintubated patients:

(1) preoperative evaluation (especially upper abdominal and thoracic surgery);

(2) adult patients with respiratory rates greater than 30 breaths/min;

(3) patients with neuromuscular disease;

(4) patients with central nervous system (CNS) depression;

(5) patients with deteriorating blood gases; and

(6) patients receiving noninvasive positive-pressure ventilation.

REF:   pg. 316           OBJ:   1

     6.   Which of the following statements about the tidal volume is true?

a.
It usually is 10 to 15 mL/kg of ideal body weight.
b.
It usually is about 25% to 30% of total lung capacity.
c.
It is made up of two components: alveolar volume and dead space volume.
d.
It has an inversely proportional relationship with minute ventilation.

ANS:  C

VT has two components: alveolar volume (VA), or the portion of VT that effectively exchanges with alveolar-capillary blood, and dead space volume (VD), or the portion of VT that does not exchange with capillary blood.

REF:   pg. 316           OBJ:   1

     7.   In healthy, spontaneously breathing patients, an occasional increase in tidal volume to three or four times the normal level, which normally occurs about six to ten times each hour, is the definition of a:

a.
sigh.
b.
cough.
c.
sneeze.
d.
forced vital capacity.

ANS:  A

In healthy, spontaneously breathing people, the VT occasionally increases to three or four times normal levels. These larger tidal breaths are known as sighs and normally occur about six to ten times each hour.

REF:   pg. 316           OBJ:   1

     8.   If intubated and mechanically ventilated patients are given shallow tidal volumes without sighs, which of the following is most likely to occur?

a.
Coughing
b.
Atelectasis
c.
Respiratory arrest
d.
Increase in secretion production

ANS:  B

If shallow breathing without occasional sighing is maintained for prolonged periods, atelectasis and pneumonia may result, especially in patients who are breathing high oxygen concentrations or who are having compromised mucociliary clearance.

REF:   pg. 316           OBJ:   1

     9.   All of the following are likely to cause a decrease in a patient’s tidal volume except:

a.
pulmonary edema.
b.
metabolic acidosis.
c.
acute respiratory distress syndrome.
d.
the postoperative period after coronary artery bypass surgery.

ANS:  B

Conditions that may cause the VT to be reduced include pneumonia, atelectasis, the postoperative period following chest and abdominal surgery, chest trauma, acute exacerbation of chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), pulmonary edema, acute restrictive diseases such as acute respiratory distress syndrome (ARDS), neuromuscular diseases, and CNS depression (especially of the respiratory centers).

REF:   pg. 316           OBJ:   1

   10.   Which of the following is least likely to cause an increase in a patient’s tidal volume?

a.
Metabolic acidosis
b.
Sepsis
c.
Metabolic alkalosis
d.
Severe neurologic injury

ANS:  C

Larger-than-normal VT may be seen with metabolic acidosis, sepsis, or severe neurologic injury.

REF:   pg. 316           OBJ:   1

   11.   In mechanically ventilated patients, the addition of positive end-expiratory pressure (PEEP) to normal tidal volumes is associated with the following effects except a(n):

a.
decrease in intrapulmonary shunting.
b.
increase in functional residual capacity.
c.
increase in partial pressure of arterial oxygen (PaO2).
d.
increase in residual volume.

ANS:  D

When normal spontaneous VT is used during continuous mandatory ventilation (CMV) without positive end-expiratory pressure (PEEP), the following occur: a reduction in functional residual capacity (FRC), an increase in intrapulmonary shunt, and a fall in partial pressure of arterial oxygen (PaO2).

REF:   pg. 316           OBJ:   1d

   12.   Patients who are ventilated with excessively large tidal volumes are at risk for:

a.
air trapping.
b.
volutrauma.
c.
emphysema.
d.
hyperventilation.

ANS:  B

The use of high-VT ventilation may predispose patients to volutrauma, a lung injury that results from overdistention of terminal respiratory units.

REF:   pg. 317           OBJ:   1a

   13.   Which of the following conditions explains why lung damage persists after recovery from a severe protracted episode of acute respiratory distress syndrome (ARDS)?

a.
Volutrauma
b.
Severity of the episode of ARDS
c.
Use of excessive amounts of PEEP during the episode
d.
Condition of the lungs before the onset of disease

ANS:  A

Volutrauma often develops in nondependent lung regions and is the main reason why lung damage persists after recovery from severe protracted ARDS.

REF:   pg. 317           OBJ:   1a

   14.   Volutrauma is most likely to develop in:

a.
the larger airways.
b.
dependent lung regions.
c.
nondependent lung regions.
d.
small airways.

ANS:  C

Volutrauma often develops in nondependent lung regions and is the main reason why lung damage persists after recovery from severe protracted ARDS.

REF:   pg. 317           OBJ:   1a

   15.   In a sedated, mechanically ventilated patient, inspiratory tidal volumes are consistently larger than expiratory tidal volumes. If it is assumed that there is no leak in the circuit, which of the following provides the best explanation for this discrepancy?

a.
Ventilator malfunction
b.
The compressibility factor of the ventilator circuit
c.
An increase in airway resistance that causes air trapping
d.
Different pressure profiles

ANS:  B

Differences often are caused by the compressible volume of the ventilator circuit or by environmental factors at different locations of the inspiratory and expiratory flow sensors (i.e., heated, humidified gases, differing flow profiles).

REF:   pg. 317           OBJ:   1 | 2

   16.   The “stacking” of breaths, which often is seen in mechanically ventilated patients with severe airway obstruction, can be caused by:

a.
ventilator malfunction.
b.
a low-measured tidal volume.
c.
insufficient expiratory time.
d.
a respiratory rate that is too low.

ANS:  C

If not enough time is allowed for exhalation before the next breath is initiated by the ventilator, the subsequent VT will “stack” on top of the previous breath.

REF:   pg. 317           OBJ:   1

   17.   Which of the following ventilator changes will have to be made if the problem of “breath stacking” is to be resolved?

a.
Increase in tidal volume
b.
Increase in respiratory rate
c.
Increase in inspiratory flow
d.
Increase in both respiratory rate and inspiratory flow

ANS:  C

Expiratory time is increased when the ventilator rate is reduced (if inspiratory time remains the same), thereby increasing the inspiratory flow rate or decreasing inspiratory time.

REF:   pg. 317           OBJ:   1

   18.   All of the following changes can decrease “breath stacking” in a mechanically ventilated patient except:

a.
a decreased ventilator rate.
b.
an increased inspiratory flow.
c.
a decreased expiratory time.
d.
a decreased mechanical tidal volume.

ANS:  C

Expiratory time is increased by reducing the ventilator rate (if inspiratory time remains the same), thereby increasing the inspiratory flow rate or decreasing the inspiratory time.

REF:   pg. 317           OBJ:   1

   19.   An important advantage of monitoring mechanical tidal volumes proximally is that:

a.
it decreases circuit resistance and dead space.
b.
it decreases the respiratory work for the patient.
c.
the measuring device is less susceptible to condensation.
d.
it eliminates the compressible volume factor of tubing circuits.

ANS:  D

Proximal volume monitoring eliminates the loss of compressible volume to the circuit and may reflect a more accurately delivered VT than does expiratory limb monitoring.

REF:   pg. 317           OBJ:   1a

   20.   Weaning failure during a spontaneous breathing trial may be predicted when the spontaneous respiratory rate is greater than:

a.
20 breaths/min.
b.
25 breaths/min.
c.
30 breaths/min.
d.
35 breaths/min.

ANS:  D

The criteria used to define failure in this breathing trial include the following: a 20% increase or decrease in blood pressure or heart rate, SpO2 less than or equal to 85% to 90%, respiratory rate greater than 35 breaths/min, a change in mental status, accessory muscle use, and the onset of diaphoresis.

REF:   pg. 318, Box 14-1                          OBJ:   1

   21.   In adult patients, spontaneous tidal volumes should be at least what value if weaning is to be successful?

a.
200 mL
b.
300 mL
c.
400 mL
d.
500 mL

ANS:  B

VT also may decrease if the patient fatigues during the spontaneous breathing trial (SBT) and should be at least 300 mL or greater than 4 mL/kg.

REF:   pg. 318           OBJ:   1

   22.   The ratio of respiratory frequency to tidal volume that is used to predict the likelihood of success in weaning the patient from mechanical ventilation is also known as:

a.
a spontaneous breathing test.
b.
the successful weaning test.
c.
the spontaneous ventilation index.
d.
the rapid-shallow breathing index.

ANS:  D

The rapid-shallow breathing index (RSBI) incorporates this spontaneous breath rate change and measures the ratio of respiratory frequency (f) to VT. RSBI = f (breaths/min)/VT (liters). If measured with a Wright spirometer and T-piece, RSBI values greater than 105 have been reported to be strong prognostic indicators of weaning failure.

REF:   pg. 318           OBJ:   1b

   23.   Which of the following values for the ratio of respiratory frequency to tidal volume would predict that the patient will be successfully weaned off the ventilator?

a.
50
b.
100
c.
150
d.
200

ANS:  A

If measured using a Wright spirometer and T-piece, RSBI values greater than 105 have been reported to be strong prognostic indicators of weaning failure.

REF:   pg. 318           OBJ:   1b

   24.   Which of the following RSBI values would predict that the patient is least likely to be successfully weaned from mechanical ventilation?

a.
25
b.
50
c.
75
d.
100

ANS:  D

If measured using a Wright spirometer and T-piece, RSBI values greater than 105 have been reported to be strong prognostic indicators of weaning failure.

REF:   pg. 318           OBJ:   1b

   25.   For weaning to be successful, the patient’s spontaneous minute ventilation needs to be less than _____ L/min.

a.
10
b.
20
c.
30
d.
40

ANS:  A

If a E greater than 10 L/min is needed for a mechanically ventilated patient to maintain a normal PaCO2, weaning is not likely to be successful.

REF:   pg. 318           OBJ:   1

   26.   The highest incidence of postoperative morbidity is associated with which of the following surgery sites?

a.
Transsternal
b.
Upper abdominal
c.
Lower abdominal
d.
Thoracoabdominal

ANS:  D

Although many factors can contribute to a reduction in vital capacity (VC) postoperatively, one of the most important is the incision site. Thoracic and abdominal surgery produce a significant fall in VC postoperatively, and this reduction may persist for a week or longer.

REF:   pg. 319           OBJ:   1 | 2

   27.   Which of the following values of VC is more consistent with impending respiratory failure?

a.
10 mL/kg
b.
30 mL/kg
c.
50 mL/kg
d.
70 mL/kg

ANS:  A

Values of less than 10 mL/kg usually are associated with impending respiratory failure.

REF:   pg. 319           OBJ:   1c

   28.   Which of the following ventilator changes is most likely to increase the functional reserve capacity (FRC) and reduce the extent of acute lung injury?

a.
Increased FIO2
b.
Increased flow
c.
Increased PEEP
d.
Decreased inspiratory time

ANS:  C

The application of PEEP prevents alveolar collapse and may reduce the extent of acute lung injury.

REF:   pg. 319           OBJ:   1d

   29.   The amount of force needed to overcome opposition to air flow in the lungs during mechanical ventilation is known as:

a.
peak pressure.
b.
airway pressure.
c.
maximal airway resistance.
d.
positive end-expiratory pressure.

ANS:  A

Peak inspiratory pressure (PIP) is the maximum pressure attained during the inspiratory phase of mechanical ventilation (see Figure 14-1). It reflects the amount of force needed to overcome opposition to air flow into the lungs.

REF:   pg. 319           OBJ:   2

   30.   The amount of force needed to maintain a mechanical tidal volume breath in the patient’s lungs is known as _____ pressure.

a.
peak
b.
static
c.
positive end-expiratory
d.
continuous positive airway

ANS:  B

The plateau pressure (also referred to as static pressure) is the pressure required to maintain delivered VT in a patient’s lungs during a period of no gas flow.

REF:   pg. 320           OBJ:   2

   31.   All of the following are likely to increase the mean airway pressure (MAP) except an increase in:

a.
flow rate.
b.
PEEP levels.
c.
peak pressure.
d.
expiratory time.

ANS:  D

Ventilator measurements that affect include CPAP and PEEP levels, inspiratory time (flow rate, flow patterns), peak pressure, and rate. A simple method of calculating is as follows:

 = [1/2 (PIP – PEEP) ´ (Inspiratory time/Total cycle time)] + PEEP

REF:   pg. 320           OBJ:   2

   32.   If auto-PEEP is present, it is most likely to be detected if the expiratory limb of the patient circuit is occluded at what point in the cycle?

a.
At the end of exhalation
b.
In the middle of inhalation
c.
In maximal inhalation
d.
At the middle of exhalation

ANS:  A

When the flow is stopped at end-exhalation, pressure equilibrates throughout the closed system and registers on the ventilator manometer.

REF:   pg. 322           OBJ:   3

   33.   Which of the following waveforms most accurately allows the clinician the recognition of auto-PEEP?

a.
Pressure-volume
b.
Pressure-time
c.
Flow-time
d.
Flow-volume

ANS:  C

The flow-time waveform can be examined to determine most accurately whether expiratory flow returns to baseline before the subsequent inhalation.

REF:   pg. 322           OBJ:   3

   34.   Compliance is defined as:

a.
elasticity.
b.
pressure change per unit of volume.
c.
volume change per unit of pressure change.
d.
volume change per unit of flow.

ANS:  C

Compliance is defined as volume change per unit of pressure change, or the amount of lung volume achieved per unit of pressure.

REF:   pg. 322           OBJ:   2

   35.   Acute respiratory distress syndrome (ARDS), pneumonia, and pulmonary edema are likely to cause a decrease in lung compliance. This is evidenced in a mechanically ventilated patient by an increase in:

a.
static pressure.
b.
expiratory time.
c.
inspiratory time.
d.
dynamic pressure.

ANS:  A

Lung diseases such as pulmonary edema, pneumothorax, pneumonia, and ARDS increase lung recoil and observed static pressure. As a result, static compliance is reduced in these situations.

REF:   pg. 322           OBJ:   2

   36.   In the intensive care unit (ICU), the airway resistance (Raw) of a mechanically ventilated patient can be estimated easily by using which of the following formulas?

a.
(Flow – Inspiratory time)/60
b.
(Peak pressure – Static pressure)/2
c.
(Peak pressure – Static pressure)/Flow
d.
(ET tube diameter – Static pressure)/Peak airway pressure

ANS:  C

REF:   pg. 323           OBJ:   2

   37.   When a patient’s mechanical ventilator has a graphic display screen, which of the following waveforms could be used to determine whether there is any leak in the system and the amount of the leak?

a.
Flow-time
b.
Volume-time
c.
Pressure-time
d.
Pressure-flow

ANS:  B

The volume-time waveform is used most often to compare inspiratory and expiratory delivered volumes. This can be particularly useful in checking for leaks within the ventilator circuit system, or in determining the amount of leak around the endotracheal tube or through a chest tube.

REF:   pg. 326           OBJ:   4

   38.   Which of the following is normally used when PEEP levels are titrated to determine optimal PEEP?

a.
Flow-time curve
b.
Volume-time curve
c.
Pressure-time curve
d.
Pressure-volume curve

ANS:  D

Some investigators have advocated using a static pressure-volume curve to titrate PEEP and tidal volume.

REF:   pg. 328           OBJ:   4

   39.   When carbon dioxide elimination is monitored, the highest levels are obtained at the:

a.
end of inhalation.
b.
end of exhalation.
c.
middle of inhalation.
d.
middle of exhalation.

ANS:  B

Exhaled alveolar carbon dioxide concentrations often are at their highest at the end of exhalation, so the term end-tidal PCO2 (PETCO2) may be used to indicate the highest exhaled carbon dioxide concentrations attained.

REF:   pg. 331           OBJ:   5

   40.   Carbon dioxide production is increased by approximately what percentage per 1° C of body temperature in patients with fever?

a.
1%
b.
10%
c.
25%
d.
50%

ANS:  B

CO2 often is increased in fever (10% increase per 1° C increase), trauma, peritonitis (25% to 50% increase), head trauma, rewarming after hypothermia, and high carbohydrate loading with total parenteral nutrition.

REF:   pg. 332           OBJ:   5

   41.   When the dead space–to–tidal volume ratio (VD/VT) is calculated, VD refers to the _____ dead space.

a.
alveolar
b.
anatomic
c.
ventilatory
d.
physiologic

ANS:  D

VD has two components: anatomic dead space and alveolar dead space. Anatomic dead space is made up of the conducting airways and normally measures about 1 mL/kg of ideal body weight. Alveolar dead space is classically defined as alveoli that are ventilated but are not perfused. The combination of anatomic and alveolar dead space is called physiologic dead space.

REF:   pg. 333           OBJ:   5 | 6

   42.   Under normal conditions, the hemoglobin is responsible for carrying approximately what percentage of the oxygen carried in the blood?

a.
66%
b.
75%
c.
88%
d.
99%

ANS:  D

Under normal conditions, the hemoglobin is responsible for carrying 99% or more of the oxygen in the blood.

REF:   pg. 333           OBJ:   6

   43.   Which of the following conditions is the most common cause of inadequate oxygenation of pulmonary capillary blood?

a.
Hypovolemia
b.
mismatch
c.
Hypoventilation
d.
Diffusion defect

ANS:  B

Traditional respiratory care has focused on the physiologic mechanisms that result in inadequate oxygenation of pulmonary capillary blood. These mechanisms include the following: mismatch (most common cause), diffusion block (rare cause),

hypoventilation, and shunt (extreme mismatch).

REF:   pg. 333           OBJ:   6 | 7

   44.   The cardiac output will increase to compensate for a decrease in oxygen tension when the PaO2 falls to below _____ mm Hg.

a.
50
b.
60
c.
70
d.
80

ANS:  A

Cardiac output is not sensitive to moderate changes in oxygen tension (PO2) and usually does not increase until the PaO2 drops to below 50 mm Hg.

REF:   pg. 334           OBJ:   6 | 7

   45.   On the oxygen dissociation curve (ODC), the P-50 refers to the:

a.
partial pressure of oxygen when the hemoglobin is 50% saturated.
b.
hemoglobin saturation when the fraction of inspired oxygen is 50%.
c.
partial pressure of oxygen when the fraction of inspired oxygen is 50%.
d.
hemoglobin saturation when the partial pressure of oxygen is 50 mm Hg.

ANS:  A

Clinically, the position of the curve is measured by tonometry or is calculated at a point where the oxygen’s partial pressure has saturated 50% of the hemoglobin (P-50).

REF:   pgs. 334-335                                  OBJ:   7

   46.   The normal compensatory mechanism for a left shift in the oxygen dissociation curve is a(n):

a.
increase in tidal volume.
b.
increase in cardiac output.
c.
increase in respiratory rate.
d.
decrease in body temperature.

ANS:  B

The normal compensatory mechanism for a left-shifted curve is an increase in cardiac output.

REF:   pg. 335           OBJ:   7

   47.   Under most clinical conditions, the PaO2 should be kept within the range of _____ mm Hg.

a.
60 to 80
b.
80 to 100
c.
100 to 120
d.
120 to 150

ANS:  A

Under most clinical conditions, the PaO2 should be kept within a range of 60 to 80 mm Hg.

REF:   pg. 335           OBJ:   7 | 8

   48.   Which level of a PaO2/FIO2 ratio is consistent with a definition of acute lung injury (ALI)?

a.
50
b.
100 to 200
c.
150
d.
200 to 300

ANS:  D

A PaO2/FIO 2 ratio of between 200 and 300 mm Hg is associated with acute lung injury (ALI) and a PaO2/FIO 2 ratio of less than 200 is associated with ARDS.

REF:   pg. 336           OBJ:   8

   49.   All of the following will cause an increase in intrapulmonary shunting except:

a.
ARDS.
b.
atelectasis.
c.
pneumonia.
d.
cystic fibrosis.

ANS:  D

Clinical states that often produce an increase in include atelectasis, pneumonia, ARDS, pulmonary edema, and, rarely, congenital heart anomalies or arteriovenous anastomosis.

REF:   pg. 336           OBJ:   8

   50.   The parameter that indicates oxygen usage throughout the whole body is:

a.
CaO2.
b.
.
c.
PaCO2.
d.
P(A – a)O2.

ANS:  B

is a measure of the partial pressure of oxygen in mixed venous blood and is an indication of oxygen usage by the entire body.

REF:   pg. 338           OBJ:   8c

   51.   The portion of delivered oxygen actually consumed and an index of the efficiency of circulation is the definition for the:

a.
oxygenation index (OI).
b.
oxygen extraction ratio (C[a – v]O2/CaO2).
c.
arterial-mixed venous oxygen content difference (C[a – v]O2).
d.
arterial-mixed venous oxygen saturation difference (S[a – v]O2).

ANS:  B

The oxygen extraction ratio identifies the portion of delivered oxygen that actually is consumed and is therefore an index of the efficiency of circulation.

REF:   pg. 340           OBJ:   10