CHT Hyperbaric Medicine Fundamentals 2 — Questions and Answers
Question 1: Which law states that the solubility of a gas in a liquid is proportional to the partial pressure of that gas above the liquid?
- Boyle's Law
- Henry's Law (Correct answer)
- Dalton's Law
- Charles's Law
Correct answer: Henry's Law
Henry's Law directly governs how increased pressure in an HBO chamber forces more oxygen into plasma and tissue fluids.
Question 2: What is the primary reason 100% oxygen is used instead of compressed air in most hyperbaric treatments?
- Air is flammable at high pressure
- Oxygen eliminates the nitrogen narcosis risk
- Oxygen maximizes tissue oxygen tension and speeds elimination of inert gas (Correct answer)
- Compressed air is not available in hospital settings
Correct answer: Oxygen maximizes tissue oxygen tension and speeds elimination of inert gas
Breathing 100% oxygen at pressure dramatically raises tissue PO2 and accelerates washout of inert gases like nitrogen.
Question 3: During a hyperbaric treatment at 2.4 ATA, what is the approximate partial pressure of oxygen when the patient breathes 100% O2?
- 0.21 ATA
- 1.0 ATA
- 2.4 ATA (Correct answer)
- 2.0 ATA
Correct answer: 2.4 ATA
Partial pressure of a pure gas equals the total pressure; at 2.4 ATA breathing 100% O2, PO2 = 2.4 ATA.
Question 4: Which of the following best describes the mechanism by which HBO reduces intracranial pressure in carbon monoxide poisoning?
- HBO chemically binds CO in the blood
- HBO-induced vasoconstriction reduces cerebral edema (Correct answer)
- HBO activates complement cascade to clear CO
- HBO increases cerebral blood flow and oxygenation
Correct answer: HBO-induced vasoconstriction reduces cerebral edema
High PO2 causes cerebral vasoconstriction, reducing edema and ICP while still delivering adequate O2 via dissolved plasma oxygen.
Question 5: A patient with decompression sickness develops worsening symptoms during ascent from an HBO treatment. What is the most appropriate immediate action?
- Stop oxygen flow and surface immediately
- Return to treatment depth and reassess (Correct answer)
- Administer IV fluids and continue ascent
- Increase ascent rate to shorten exposure
Correct answer: Return to treatment depth and reassess
Worsening on ascent (omitted decompression response) requires returning to treatment depth per the applicable US Navy Treatment Table.
Question 6: Which tissue has the highest risk of oxygen toxicity seizure during routine hyperbaric oxygen therapy?
- Liver
- Kidney
- Central nervous system (Correct answer)
- Peripheral muscle
Correct answer: Central nervous system
CNS oxygen toxicity (Paul Bert effect) manifests as seizures and is the primary concern during high-pressure HBO treatments.
Question 7: What physiological effect of HBO directly promotes angiogenesis in hypoxic wound beds?
- Increased carboxyhemoglobin dissociation
- Cyclic hyperoxia–normoxia stimulating VEGF release (Correct answer)
- Direct bactericidal action on anaerobes
- Reduced blood viscosity from plasma expansion
Correct answer: Cyclic hyperoxia–normoxia stimulating VEGF release
Alternating high and normal O2 tensions between HBO sessions stimulates vascular endothelial growth factor (VEGF) and new capillary formation.
CHT Hyperbaric Medicine Fundamentals 2
Which law states that the solubility of a gas in a liquid is proportional to the partial pressure of that gas above the liquid?