NBRC MOCK TMC EXAM REVIEW NEWEST ACTUAL
EXAM COMPLETE TESTBANK ALL 50 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)
|ALREADY GRADED A+.
QUESTION
A patient is receiving oxygen from an E cylinder at 4 L/min through a nasal
cannula. The cylinder pressure gauge reads 1900 psig. How long will the cylinder
run until it is completely empty?
a. 47 minutes
b. 1.7 hours
c. 2.2 hours
d. 3.6 hours
CORRECT ANS: c. 2.2 hours
EXPERT RATIONALE
To calculate the duration of oxygen remaining in a cylinder, the formula is:
(cylinder pressure × cylinder factor) ÷ flow rate. For an E cylinder, the conversion
factor is 0.28. Therefore, (1900 psig × 0.28) ÷ 4 L/min = 532 ÷ 4 = 133 minutes.
Converting 133 minutes to hours gives 2 hours and 13 minutes (approximately 2.2
hours). The correct answer is C, 2.2 hours. The respiratory therapist must be able
to calculate cylinder duration to ensure that patients receive uninterrupted
oxygen therapy and to plan for timely cylinder changes. Miscalculations can lead
to sudden oxygen depletion, compromising patient safety.
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, QUESTION
After the respiratory therapist sets up a nonrebreathing mask on a patient at a
flow rate of 10 L/min, the reservoir bag collapses before the patient finishes
inspiring. The respiratory therapist should take which of the following actions?
a. Change to a simple mask at a flow rate of 10 L/min
b. Remove the one-way valve from the exhalation port
c. Place the patient on continuous positive airway pressure (CPAP)
d. Increase the flow rate to 15 L/min
CORRECT ANS: d. Increase the flow rate to 15 L/min
EXPERT RATIONALE
A nonrebreathing mask requires a high oxygen flow rate (typically 10-15 L/min) to
keep the reservoir bag inflated throughout the patient's inspiration. If the bag
collapses before the patient finishes inspiring, it indicates that the flow rate is
insufficient to meet the patient's inspiratory flow demand. The appropriate action
is to increase the flow rate to 15 L/min, which should provide adequate flow to
maintain reservoir bag inflation and deliver the prescribed FiO2. Changing to a
simple mask would reduce the FiO2 delivered. Removing the one-way valve
would convert the mask to a partial rebreathing mask, altering the FiO2. CPAP is
not indicated solely for this issue.
QUESTION
A patient with carbon monoxide (CO) poisoning can best be treated with which of
the following therapies?
a. Nasal cannula at 6 L/min
b. Simple O2 mask at 10 L/min
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, c. CPAP and 60% O2
d. Nonrebreathing mask
CORRECT ANS: d. Nonrebreathing mask
EXPERT RATIONALE
Carbon monoxide (CO) poisoning requires the administration of high
concentrations of oxygen to facilitate the dissociation of CO from hemoglobin
and to accelerate its elimination from the body. The half-life of
carboxyhemoglobin (COHb) is approximately 4-6 hours when breathing room air,
but it decreases to approximately 1 hour when breathing 100% oxygen via a
nonrebreathing mask. A nonrebreathing mask delivers the highest FiO2
(approaching 100%) of the listed options, making it the most appropriate therapy.
Nasal cannula at 6 L/min and simple masks do not deliver adequate FiO2. CPAP
with 60% O2 delivers a lower FiO2 than a nonrebreathing mask.
QUESTION
The following arterial blood gas levels have been obtained from a patient using a
60% aerosol mask:
pH: 7.47
PaCO2: 31 mmHg
PaO2: 58 mmHg
What should the respiratory therapist recommend at this time?
a. Place the patient on CPAP
b. Increase the O2 to 70%
c. Intubate and place the patient on mechanical ventilation
d. Change to a nonrebreathing mask
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, CORRECT ANS: a. Place the patient on CPAP
EXPERT RATIONALE
The patient is receiving a high FiO2 of 60% but still has a PaO2 of only 58 mmHg,
indicating significant hypoxemia despite high oxygen delivery. This suggests a
severe ventilation/perfusion (V/Q) mismatch or intrapulmonary shunting, which is
often seen in conditions such as pulmonary edema, ARDS, or atelectasis. The
appropriate next step is to apply CPAP, which recruits alveoli, increases functional
residual capacity, and improves oxygenation by decreasing intrapulmonary
shunting. Increasing the FiO2 further is unlikely to significantly improve PaO2 due
to the underlying shunt physiology. Intubation would be premature if the patient
is stable and CPAP can be trialed. Changing to a nonrebreathing mask may not
address the underlying shunt.
QUESTION
Given the following data, what is the patient's total arterial oxygen content?
pH: 7.41
PaCO2: 37 mmHg
PaO2: 88 mmHg
HCO3: 26 mEq/L
SaO2: 95%
Hb: 14 g/dL
a. 12 mL/dL
b. 14 mL/dL
c. 16 mL/dL
d. 18 mL/dL
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EXAM COMPLETE TESTBANK ALL 50 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)
|ALREADY GRADED A+.
QUESTION
A patient is receiving oxygen from an E cylinder at 4 L/min through a nasal
cannula. The cylinder pressure gauge reads 1900 psig. How long will the cylinder
run until it is completely empty?
a. 47 minutes
b. 1.7 hours
c. 2.2 hours
d. 3.6 hours
CORRECT ANS: c. 2.2 hours
EXPERT RATIONALE
To calculate the duration of oxygen remaining in a cylinder, the formula is:
(cylinder pressure × cylinder factor) ÷ flow rate. For an E cylinder, the conversion
factor is 0.28. Therefore, (1900 psig × 0.28) ÷ 4 L/min = 532 ÷ 4 = 133 minutes.
Converting 133 minutes to hours gives 2 hours and 13 minutes (approximately 2.2
hours). The correct answer is C, 2.2 hours. The respiratory therapist must be able
to calculate cylinder duration to ensure that patients receive uninterrupted
oxygen therapy and to plan for timely cylinder changes. Miscalculations can lead
to sudden oxygen depletion, compromising patient safety.
1 | Page
, QUESTION
After the respiratory therapist sets up a nonrebreathing mask on a patient at a
flow rate of 10 L/min, the reservoir bag collapses before the patient finishes
inspiring. The respiratory therapist should take which of the following actions?
a. Change to a simple mask at a flow rate of 10 L/min
b. Remove the one-way valve from the exhalation port
c. Place the patient on continuous positive airway pressure (CPAP)
d. Increase the flow rate to 15 L/min
CORRECT ANS: d. Increase the flow rate to 15 L/min
EXPERT RATIONALE
A nonrebreathing mask requires a high oxygen flow rate (typically 10-15 L/min) to
keep the reservoir bag inflated throughout the patient's inspiration. If the bag
collapses before the patient finishes inspiring, it indicates that the flow rate is
insufficient to meet the patient's inspiratory flow demand. The appropriate action
is to increase the flow rate to 15 L/min, which should provide adequate flow to
maintain reservoir bag inflation and deliver the prescribed FiO2. Changing to a
simple mask would reduce the FiO2 delivered. Removing the one-way valve
would convert the mask to a partial rebreathing mask, altering the FiO2. CPAP is
not indicated solely for this issue.
QUESTION
A patient with carbon monoxide (CO) poisoning can best be treated with which of
the following therapies?
a. Nasal cannula at 6 L/min
b. Simple O2 mask at 10 L/min
2 | Page
, c. CPAP and 60% O2
d. Nonrebreathing mask
CORRECT ANS: d. Nonrebreathing mask
EXPERT RATIONALE
Carbon monoxide (CO) poisoning requires the administration of high
concentrations of oxygen to facilitate the dissociation of CO from hemoglobin
and to accelerate its elimination from the body. The half-life of
carboxyhemoglobin (COHb) is approximately 4-6 hours when breathing room air,
but it decreases to approximately 1 hour when breathing 100% oxygen via a
nonrebreathing mask. A nonrebreathing mask delivers the highest FiO2
(approaching 100%) of the listed options, making it the most appropriate therapy.
Nasal cannula at 6 L/min and simple masks do not deliver adequate FiO2. CPAP
with 60% O2 delivers a lower FiO2 than a nonrebreathing mask.
QUESTION
The following arterial blood gas levels have been obtained from a patient using a
60% aerosol mask:
pH: 7.47
PaCO2: 31 mmHg
PaO2: 58 mmHg
What should the respiratory therapist recommend at this time?
a. Place the patient on CPAP
b. Increase the O2 to 70%
c. Intubate and place the patient on mechanical ventilation
d. Change to a nonrebreathing mask
3 | Page
, CORRECT ANS: a. Place the patient on CPAP
EXPERT RATIONALE
The patient is receiving a high FiO2 of 60% but still has a PaO2 of only 58 mmHg,
indicating significant hypoxemia despite high oxygen delivery. This suggests a
severe ventilation/perfusion (V/Q) mismatch or intrapulmonary shunting, which is
often seen in conditions such as pulmonary edema, ARDS, or atelectasis. The
appropriate next step is to apply CPAP, which recruits alveoli, increases functional
residual capacity, and improves oxygenation by decreasing intrapulmonary
shunting. Increasing the FiO2 further is unlikely to significantly improve PaO2 due
to the underlying shunt physiology. Intubation would be premature if the patient
is stable and CPAP can be trialed. Changing to a nonrebreathing mask may not
address the underlying shunt.
QUESTION
Given the following data, what is the patient's total arterial oxygen content?
pH: 7.41
PaCO2: 37 mmHg
PaO2: 88 mmHg
HCO3: 26 mEq/L
SaO2: 95%
Hb: 14 g/dL
a. 12 mL/dL
b. 14 mL/dL
c. 16 mL/dL
d. 18 mL/dL
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