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Free CHT Practice Questions

10 free, exam-style CHT (CHT) practice questions with answers and explanations. No signup required. Work through them below, then take the full free CHT practice test to study every exam domain.

Question 1

A scuba diver surfaces too quickly while holding their breath and develops sudden neurological symptoms consistent with arterial gas embolism. Which gas law BEST explains why the gas in the lungs caused this injury during ascent?

  1. Henry's Law, because dissolved gas comes out of solution as pressure falls
  2. Dalton's Law, because each gas exerts its own partial pressure
  3. Boyle's Law, because trapped gas expands as ambient pressure decreases
  4. Graham's Law, because lighter gases diffuse across the alveoli faster
Show answer & explanation

Correct answer: C - Boyle's Law, because trapped gas expands as ambient pressure decreases

Question 2

A treatment protocol calls for compressing a patient to 60 feet of sea water (fsw). What is the absolute pressure at this depth?

  1. 1.8 ATA
  2. 2.8 ATA
  3. 3.0 ATA
  4. 2.0 ATA
Show answer & explanation

Correct answer: B - 2.8 ATA

Question 3

Under NFPA 99, at what oxygen concentration by volume does an environment meet the definition of an oxygen-enriched atmosphere, triggering fire-safety controls?

  1. Greater than 23.5% by volume
  2. Greater than 21.0% by volume
  3. Greater than 25.0% by volume
  4. Greater than 28.0% by volume
Show answer & explanation

Correct answer: A - Greater than 23.5% by volume

Question 4

A facility runs both monoplace and multiplace chambers. In a typical MULTIPLACE chamber, the chamber is pressurized with which gas, and how does the patient receive oxygen?

  1. Pressurized with air; patient breathes 100% oxygen via a mask or hood
  2. Pressurized with 100% oxygen; patient breathes the surrounding chamber gas directly
  3. Pressurized with heliox; patient breathes medical air delivered by a tight mask
  4. Pressurized with nitrox; patient breathes the surrounding chamber gas directly
Show answer & explanation

Correct answer: A - Pressurized with air; patient breathes 100% oxygen via a mask or hood

Question 5

Before a hyperbaric treatment, a technologist reviews a patient's history. Which finding is an ABSOLUTE contraindication to hyperbaric oxygen therapy until it is addressed?

  1. Claustrophobia with a history of anxiety
  2. An untreated pneumothorax
  3. A seizure disorder controlled with medication
  4. An upper respiratory infection with congestion
Show answer & explanation

Correct answer: B - An untreated pneumothorax

Question 6

Midway through a treatment at depth, a patient reports tinnitus and facial twitching and becomes irritable. The technologist recognizes early central nervous system oxygen toxicity. This CNS effect is also known as the:

  1. Lorrain Smith effect
  2. Lichtenberg effect
  3. Paul Bert effect
  4. Haldane effect
Show answer & explanation

Correct answer: C - Paul Bert effect

Question 7

A diver presents with pain-only (Type I) decompression sickness. Symptoms resolve completely within the first 10 minutes at 60 fsw and the neurological exam is normal. Which US Navy Treatment Table is appropriate?

  1. Treatment Table 6A
  2. Treatment Table 4
  3. Treatment Table 6
  4. Treatment Table 5
Show answer & explanation

Correct answer: D - Treatment Table 5

Question 8

A conscious patient struggles to equalize middle-ear pressure during compression. The technologist coaches a technique that involves pinching the nose closed and swallowing. This maneuver is called the:

  1. Toynbee maneuver
  2. Valsalva maneuver
  3. Frenzel maneuver
  4. Politzer maneuver
Show answer & explanation

Correct answer: A - Toynbee maneuver

Question 9

A patient scheduled for elective hyperbaric oxygen therapy has a documented history of receiving bleomycin chemotherapy. Why does this warrant caution before proceeding?

  1. It substantially increases the risk of serious middle-ear and sinus barotrauma
  2. It is associated with an increased risk of pulmonary oxygen toxicity
  3. It significantly lowers the seizure threshold throughout the entire treatment
  4. It interferes with the accuracy of transcutaneous oxygen tension readings
Show answer & explanation

Correct answer: B - It is associated with an increased risk of pulmonary oxygen toxicity

Question 10

A technologist performs transcutaneous oximetry (TCOM) on a lower-extremity wound. The electrode heats the skin to roughly 44 degrees C to arterialize the capillary bed. Generally, what periwound value indicates oxygen availability adequate to support wound healing?

  1. At least 10 mmHg
  2. At least 25 mmHg
  3. At least 40 mmHg
  4. At least 75 mmHg
Show answer & explanation

Correct answer: C - At least 40 mmHg

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