TMC Exam (Therapist Multiple-Choice) –
Comprehensive Practice Exam
EXAM OVERVIEW
The Therapist Multiple-Choice (TMC) Examination is the first step toward
becoming a Certified Respiratory Therapist (CRT) and, ultimately, a
Registered Respiratory Therapist (RRT). The exam emphasizes clinical
decision-making, patient safety, and evidence-based respiratory care.
Key content areas include patient evaluation and assessment, equipment
and therapeutic procedures, infection control and safety, oxygenation and
ventilation management, pharmacology for respiratory care, and neonatal
and pediatric respiratory therapy.
SECTION 1: Oxygen & Medical Gas Therapy (Questions 1-15)
Q1. A patient is receiving O₂ from an E cylinder at 4 L/min through a
nasal cannula. The cylinder pressure is 1900 psig. How long will the
cylinder run until it is empty?
• A) 47 minutes
• B) 1.7 hours
• C) 2.2 hours
• D) 3.6 hours
Answer: C – E cylinder factor = 0.28. Duration = (pressure × factor) / flow =
(1900 × 0.28) / 4 = = 133 minutes = 2 hours, 13 minutes ≈ 2.2 hours.
Q2. After the RT sets up a non-rebreathing mask on a patient at a flow
rate of 10 L/min, the reservoir bag collapses before the patient finishes
inspiring. The RT should do which of the following?
• 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
Answer: D – Reservoir bag collapse indicates inadequate flow to meet the
patient's inspiratory demand. Increasing the flow rate ensures the bag
remains inflated and the patient receives the prescribed FiO₂.
Q3. A patient with carbon monoxide (CO) poisoning can best be treated
with which of the following therapies?
• 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 non-rebreathing mask
Answer: D – CO poisoning is treated with 100% oxygen via non-rebreathing
mask to displace CO from hemoglobin. The half-life of carboxyhemoglobin
is reduced from 4-6 hours (on room air) to 1-2 hours (on 100% O₂) and to
about 20 minutes in hyperbaric O₂. The mask must be sealed properly with
a tight fit.
Q4. Which of the following devices requires the liter flow to be
recorded rather than the FiO₂ because the oxygen percentage is not
predictably accurate?
• A) Air-entrainment mask
• B) Non-rebreather mask
• C) Nasal cannula
• D) Aerosol mask
,Answer: C – With a nasal cannula, the actual FiO₂ depends on the patient's
inspiratory flow and breathing pattern; only the liter flow can be reliably
recorded. The oxygen percentage is not predictably accurate.
Q5. Given the following data, what is the patient's total arterial O₂
content?
• pH: 7.41
• PaCO₂: 37 mmHg
• PaO₂: 88 mmHg
• SaO₂: 95%
• Hb: 14 g/dL
• A) 12 mL/dL
• B) 14 mL/dL
• C) 16 mL/dL
• D) 18 mL/dL
Answer: D – CaO₂ = (Hb × 1.36 × SaO₂) + (0.003 × PaO₂) = (14 × 1.36 × 0.95)
+ (0.003 × 88) = 18.088 + 0.264 = 18.352 mL/dL. 1.36 is the oxygen-carrying
capacity of hemoglobin; 0.003 is the solubility coefficient of oxygen in
plasma.
Q6. A patient receiving 38 mg H₂O per liter of gas from a nebulizer has a
humidity deficit of which of the following?
• A) 6 mg/L
• B) 9 mg/L
• C) 12 mg/L
• D) 18 mg/L
, Answer: A – At body temperature (37°C), fully saturated gas contains 44 mg
H₂O/L. Humidity deficit = 44 - 38 = 6 mg/L. The deficit represents the
amount of water vapor the gas needs to become fully saturated at body
temperature.
Q7. What volume of water is being delivered when a heated humidifier
is delivering 100% body humidity to a patient's airway?
• A) 24 mg/L
• B) 37 mg/L
• C) 44 mg/L
• D) 47 mg/L
Answer: C – 100% body humidity at 37°C equals 44 mg H₂O/L. This is the
maximum water vapor capacity of gas at body temperature.
Q8. Secretions tend to become thicker if the inspired air has which of
the following characteristics?
• A) A relative humidity of 100% at body temperature
• B) 32 mg H₂O per liter of gas
• C) A water vapor pressure of 47 mmHg
• D) 48 mg H₂O per liter of gas
Answer: B – Inspired gas with 32 mg H₂O/L is under-humidified (normal at
37°C is 44 mg/L). Low humidity dries airway secretions, making them
thicker and more difficult to clear.
Q9. A physician has ordered O₂ for a patient with a spontaneous tidal
volume of 500 mL and an inspiratory time of 1 second. Which O₂
delivery device will deliver a flow that meets or exceeds this patient's
inspiratory flow?
Comprehensive Practice Exam
EXAM OVERVIEW
The Therapist Multiple-Choice (TMC) Examination is the first step toward
becoming a Certified Respiratory Therapist (CRT) and, ultimately, a
Registered Respiratory Therapist (RRT). The exam emphasizes clinical
decision-making, patient safety, and evidence-based respiratory care.
Key content areas include patient evaluation and assessment, equipment
and therapeutic procedures, infection control and safety, oxygenation and
ventilation management, pharmacology for respiratory care, and neonatal
and pediatric respiratory therapy.
SECTION 1: Oxygen & Medical Gas Therapy (Questions 1-15)
Q1. A patient is receiving O₂ from an E cylinder at 4 L/min through a
nasal cannula. The cylinder pressure is 1900 psig. How long will the
cylinder run until it is empty?
• A) 47 minutes
• B) 1.7 hours
• C) 2.2 hours
• D) 3.6 hours
Answer: C – E cylinder factor = 0.28. Duration = (pressure × factor) / flow =
(1900 × 0.28) / 4 = = 133 minutes = 2 hours, 13 minutes ≈ 2.2 hours.
Q2. After the RT sets up a non-rebreathing mask on a patient at a flow
rate of 10 L/min, the reservoir bag collapses before the patient finishes
inspiring. The RT should do which of the following?
• 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
Answer: D – Reservoir bag collapse indicates inadequate flow to meet the
patient's inspiratory demand. Increasing the flow rate ensures the bag
remains inflated and the patient receives the prescribed FiO₂.
Q3. A patient with carbon monoxide (CO) poisoning can best be treated
with which of the following therapies?
• 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 non-rebreathing mask
Answer: D – CO poisoning is treated with 100% oxygen via non-rebreathing
mask to displace CO from hemoglobin. The half-life of carboxyhemoglobin
is reduced from 4-6 hours (on room air) to 1-2 hours (on 100% O₂) and to
about 20 minutes in hyperbaric O₂. The mask must be sealed properly with
a tight fit.
Q4. Which of the following devices requires the liter flow to be
recorded rather than the FiO₂ because the oxygen percentage is not
predictably accurate?
• A) Air-entrainment mask
• B) Non-rebreather mask
• C) Nasal cannula
• D) Aerosol mask
,Answer: C – With a nasal cannula, the actual FiO₂ depends on the patient's
inspiratory flow and breathing pattern; only the liter flow can be reliably
recorded. The oxygen percentage is not predictably accurate.
Q5. Given the following data, what is the patient's total arterial O₂
content?
• pH: 7.41
• PaCO₂: 37 mmHg
• PaO₂: 88 mmHg
• SaO₂: 95%
• Hb: 14 g/dL
• A) 12 mL/dL
• B) 14 mL/dL
• C) 16 mL/dL
• D) 18 mL/dL
Answer: D – CaO₂ = (Hb × 1.36 × SaO₂) + (0.003 × PaO₂) = (14 × 1.36 × 0.95)
+ (0.003 × 88) = 18.088 + 0.264 = 18.352 mL/dL. 1.36 is the oxygen-carrying
capacity of hemoglobin; 0.003 is the solubility coefficient of oxygen in
plasma.
Q6. A patient receiving 38 mg H₂O per liter of gas from a nebulizer has a
humidity deficit of which of the following?
• A) 6 mg/L
• B) 9 mg/L
• C) 12 mg/L
• D) 18 mg/L
, Answer: A – At body temperature (37°C), fully saturated gas contains 44 mg
H₂O/L. Humidity deficit = 44 - 38 = 6 mg/L. The deficit represents the
amount of water vapor the gas needs to become fully saturated at body
temperature.
Q7. What volume of water is being delivered when a heated humidifier
is delivering 100% body humidity to a patient's airway?
• A) 24 mg/L
• B) 37 mg/L
• C) 44 mg/L
• D) 47 mg/L
Answer: C – 100% body humidity at 37°C equals 44 mg H₂O/L. This is the
maximum water vapor capacity of gas at body temperature.
Q8. Secretions tend to become thicker if the inspired air has which of
the following characteristics?
• A) A relative humidity of 100% at body temperature
• B) 32 mg H₂O per liter of gas
• C) A water vapor pressure of 47 mmHg
• D) 48 mg H₂O per liter of gas
Answer: B – Inspired gas with 32 mg H₂O/L is under-humidified (normal at
37°C is 44 mg/L). Low humidity dries airway secretions, making them
thicker and more difficult to clear.
Q9. A physician has ordered O₂ for a patient with a spontaneous tidal
volume of 500 mL and an inspiratory time of 1 second. Which O₂
delivery device will deliver a flow that meets or exceeds this patient's
inspiratory flow?
