CHT Treatment Protocols & Procedures 2 — Questions and Answers
Question 1: Which UHMS-approved treatment table is used for arterial gas embolism when Table 6 fails to resolve symptoms?
- Table 5
- Table 6A (Correct answer)
- Table 9
- Table 4
Correct answer: Table 6A
Table 6A extends Table 6 with an additional 60-minute oxygen period at 60 fsw for cases where symptoms persist.
Question 2: During a hyperbaric oxygen treatment, a patient reports vision changes and facial twitching. What is the most likely cause and correct action?
- Ear squeeze; continue treatment and monitor
- CNS oxygen toxicity; remove oxygen mask immediately (Correct answer)
- Hypoglycemia; administer oral glucose
- Nitrogen narcosis; ascend to shallower depth
Correct answer: CNS oxygen toxicity; remove oxygen mask immediately
Facial twitching with vision changes are prodromal signs of CNS oxygen toxicity, requiring immediate removal of the oxygen mask and air break.
Question 3: What is the standard air break duration in a treatment table that includes air breaks to reduce oxygen toxicity risk?
- 3 minutes
- 5 minutes (Correct answer)
- 10 minutes
- 15 minutes
Correct answer: 5 minutes
Standard air breaks are typically 5 minutes of air breathing between oxygen periods to reduce cumulative CNS oxygen toxicity risk.
Question 4: A tender inside the chamber should breathe oxygen during a treatment for decompression sickness primarily to:
- Prevent nitrogen narcosis at depth
- Reduce the risk of the tender developing decompression sickness (Correct answer)
- Maintain consciousness in an emergency
- Equalize pressure more efficiently
Correct answer: Reduce the risk of the tender developing decompression sickness
Breathing oxygen at depth reduces the tender's nitrogen loading, lowering their risk of developing decompression sickness during the treatment dive.
Question 5: In the U.S. Navy Table 6 protocol, oxygen is breathed at 60 fsw (2.8 ATA) in cycles. What is the oxygen breathing schedule at 60 fsw?
- Two 20-minute periods with one 5-minute air break
- Three 20-minute periods with two 5-minute air breaks (Correct answer)
- Two 30-minute periods with one 10-minute air break
- Four 15-minute periods with three 5-minute air breaks
Correct answer: Three 20-minute periods with two 5-minute air breaks
Table 6 includes three 20-minute oxygen periods separated by two 5-minute air breaks at 60 fsw before the ascent phase.
Question 6: Which condition is considered an absolute contraindication to hyperbaric oxygen therapy?
- Pregnancy in the first trimester
- Untreated pneumothorax (Correct answer)
- Claustrophobia
- Fever above 38°C
Correct answer: Untreated pneumothorax
Untreated pneumothorax is an absolute contraindication because increased pressure can cause tension pneumothorax during treatment.
Question 7: When treating carbon monoxide poisoning, the primary mechanism by which hyperbaric oxygen accelerates CO elimination is:
- Increasing hemoglobin production
- Competitively displacing CO from hemoglobin by mass action (Correct answer)
- Oxidizing CO to CO2 within the bloodstream
- Stimulating cytochrome P450 enzyme activity
Correct answer: Competitively displacing CO from hemoglobin by mass action
High partial pressures of oxygen competitively displace CO from hemoglobin by mass action, dramatically accelerating the half-life reduction of carboxyhemoglobin.
CHT Treatment Protocols & Procedures 2
Which UHMS-approved treatment table is used for arterial gas embolism when Table 6 fails to resolve symptoms?