CHT Hyperbaric Medicine Fundamentals 3 — Questions and Answers
Question 1: According to Charles's Law, if a gas is heated at constant pressure, its volume will:
- Decrease proportionally
- Remain unchanged
- Increase proportionally (Correct answer)
- Double regardless of temperature change
Correct answer: Increase proportionally
Charles's Law states volume is directly proportional to absolute temperature at constant pressure (V ∝ T).
Question 2: Which condition is an ABSOLUTE contraindication to hyperbaric oxygen therapy?
- Controlled hypertension
- Untreated pneumothorax (Correct answer)
- Mild claustrophobia
- Recent cataract surgery
Correct answer: Untreated pneumothorax
An untreated pneumothorax can tension under pressure and is the only universally accepted absolute contraindication to HBO.
Question 3: The US Navy Treatment Table 6 is the standard protocol for which condition?
- Arterial gas embolism (Correct answer)
- Carbon monoxide poisoning
- Diabetic foot ulcers
- Radiation necrosis
Correct answer: Arterial gas embolism
USN Table 6 reaches 2.8 ATA and is the primary treatment for arterial gas embolism and serious decompression sickness.
Question 4: What is the primary role of a 'air break' during an HBO session?
- Allow the chamber to repressurize with fresh gas
- Reduce pulmonary and CNS oxygen toxicity risk (Correct answer)
- Let the patient communicate with the operator
- Equalize pressure within the patient's ears
Correct answer: Reduce pulmonary and CNS oxygen toxicity risk
Air breaks (5 min of air breathing) lower cumulative oxygen dose and reduce the risk of both CNS and pulmonary O2 toxicity.
Question 5: A monoplace hyperbaric chamber is pressurized with which gas?
- Air
- Nitrogen–oxygen mix
- 100% oxygen (Correct answer)
- Heliox
Correct answer: 100% oxygen
Monoplace chambers are pressurized with 100% oxygen, so the patient breathes the ambient chamber gas directly.
Question 6: Which sign or symptom should prompt an immediate chamber stop and assessment for CNS oxygen toxicity?
- Bilateral tinnitus
- Muscle twitching or lip tingling (VENTID symptoms) (Correct answer)
- Mild headache
- Ear fullness with equalization difficulty
Correct answer: Muscle twitching or lip tingling (VENTID symptoms)
VENTID (Visual, Ears, Nausea, Twitching, Irritability, Dizziness) symptoms are early warning signs of CNS O2 toxicity requiring treatment pause.
Question 7: Fick's Law of Diffusion states that gas transfer across a membrane is increased by which factor?
- Thicker membrane
- Smaller surface area
- Higher partial pressure gradient (Correct answer)
- Lower solubility coefficient
Correct answer: Higher partial pressure gradient
Fick's Law: diffusion rate is directly proportional to the pressure gradient, surface area, and solubility, and inversely proportional to membrane thickness.
CHT Hyperbaric Medicine Fundamentals 3
According to Charles's Law, if a gas is heated at constant pressure, its volume will: