CHT CHT Physics & Gas Laws in Hyperbaric Medicine 1 — Questions and Answers
Question 1: According to Boyle's Law, if pressure in a hyperbaric chamber doubles, the volume of a trapped gas will:
- Halve (Correct answer)
- Double
- Remain unchanged
- Quadruple
Correct answer: Halve
Boyle's Law states that at constant temperature, pressure and volume are inversely proportional, so doubling pressure halves the gas volume.
Question 2: At 2 ATA breathing 100% oxygen, the partial pressure of oxygen is approximately:
- 760 mmHg
- 1520 mmHg (Correct answer)
- 380 mmHg
- 2280 mmHg
Correct answer: 1520 mmHg
At 2 ATA, PO2 = 2 × 760 mmHg = 1520 mmHg, since partial pressure scales directly with absolute pressure.
Question 3: Henry's Law is most relevant in hyperbaric medicine because it explains:
- Why gas volumes decrease under pressure
- Why more oxygen dissolves in blood at higher pressures (Correct answer)
- Why body temperature affects gas behavior
- Why different gases diffuse at different rates
Correct answer: Why more oxygen dissolves in blood at higher pressures
Henry's Law states that the amount of gas dissolved in a liquid is proportional to its partial pressure, explaining increased plasma oxygen dissolution during HBOT.
Question 4: Dalton's Law of Partial Pressures states that:
- Gas volume is inversely proportional to pressure
- Total pressure equals the sum of partial pressures of each component gas (Correct answer)
- Gas volume is directly proportional to temperature
- Dissolved gas is proportional to membrane thickness
Correct answer: Total pressure equals the sum of partial pressures of each component gas
Dalton's Law states that the total pressure of a gas mixture equals the sum of the individual partial pressures of each component gas.
Question 5: One atmosphere absolute (1 ATA) is equivalent to approximately:
- 14.7 psi (Correct answer)
- 29.4 psi
- 7.35 psi
- 33 psi
Correct answer: 14.7 psi
1 ATA equals approximately 14.7 psi (pounds per square inch), which is standard sea-level atmospheric pressure.
Question 6: Every 33 feet of seawater (fsw) of depth adds how much pressure?
- 0.5 ATA
- 1 ATA (Correct answer)
- 2 ATA
- 1.5 ATA
Correct answer: 1 ATA
Every 33 fsw adds 1 ATA of gauge pressure, so a patient at 33 fsw depth experiences 2 ATA absolute (1 atmospheric + 1 from depth).
CHT CHT Physics & Gas Laws in Hyperbaric Medicine 1
According to Boyle's Law, if pressure in a hyperbaric chamber doubles, the volume of a trapped gas will: