Hyperbaric oxygen therapy

Question 1

Units

Answer 1

Sea level: 1 ATA - 760 mm Hg - 14 psi - PP of oxygen: 21% X 760 = 160 mm Hg

33 FSW: 2 ATA - 1520 mm Hg - 28 psi - PP of oxygen: 21% x 1520 = 320 mm Hg

66 FSBoyW: 3 ATA - 2280 mm Hg - 42 psi - PP of oxygen: 21% x 2280 = 480 mm Hg

2 ATA of 100% FiO2 - PP of oxygen: 100% x 1520 = 1520 mm Hg

Question 2

Boyles’s law. (bubble law)

Answer 2

At constant temperature: V = 1/P x constant

Question 3

Charles law.

Answer 3

At constant pressure: V = T x constant

Question 4

Dalton’s law

Answer 4

P total = P1 + P2 + P3

Question 5

Effect of Increased PPO2

Answer 5

At room air, transcutaneous P02 is about 40 mm Hg, With 100% oxygen challenge, this should come up to about 90 mm Hg. At 2 ATA, 100% oxygen, this should be about 425 mm Hg.

Question 6

Side effects of HBOT

Answer 6

1. Middle ear barotrauma
2. Sinus squeeze
3. Claustrophobia
4. Progressive myopia (reversible)
5. Progression of cataracts (irreversible)
6. CNS oxygen toxicity seizure
7. Pulmonary oxygen toxicity
8. Transient increase in BP and decrease in HR
9. Pulmonary barotrauma

Question 7

Absolute contraindications for HBO

Answer 7

1. Untreated pneumothorax
2. Concomitant treatment with doxorubicin
3. Concomitant or recent treatment with bleomycin

Question 8

Relative contraindications

Answer 8

1. Acute viral upper respiratory infection
2. Fever
3. Seizure disorder
4. Emphysema
5. History of spontaneous pneumothorax
6. History of otosclerosis surgery
7. congenital spherocytosis
8. History of optic neuritis