CHS Patient Evaluation & Treatment Protocols 2 — Questions and Answers
Question 1: A patient with a tympanic membrane perforation is referred for hyperbaric oxygen therapy. What is the most appropriate action?
- Proceed with treatment as the perforation acts as a natural pressure equalizer (Correct answer)
- Delay treatment until the perforation heals completely
- Insert myringotomy tubes before starting therapy
- Reduce treatment pressure to 1.5 ATA to minimize barotrauma risk
Correct answer: Proceed with treatment as the perforation acts as a natural pressure equalizer
A tympanic membrane perforation actually eliminates the risk of middle ear barotrauma since pressure equalizes freely through the opening.
Question 2: Which of the following best describes the oxygen window concept as it applies to hyperbaric treatment of decompression sickness?
- The period of time oxygen can be safely administered before toxicity
- The partial pressure gradient created when oxygen replaces inert gas, facilitating bubble reabsorption (Correct answer)
- The pressure range at which oxygen therapy is most effective
- The therapeutic window between 2.0 and 2.8 ATA for oxygen delivery
Correct answer: The partial pressure gradient created when oxygen replaces inert gas, facilitating bubble reabsorption
The oxygen window refers to the unsaturation created when metabolically consumed oxygen is not replaced by inert gas, enhancing inert gas elimination from bubbles.
Question 3: A diabetic patient with a non-healing wound has an ankle-brachial index (ABI) of 0.45. Before proceeding with HBO therapy, what intervention is most critical?
- Increase the number of HBO sessions to 60
- Vascular surgery consultation to address arterial insufficiency (Correct answer)
- Apply a topical growth factor to the wound
- Begin systemic hyperbaric oxygen treatments immediately to improve perfusion
Correct answer: Vascular surgery consultation to address arterial insufficiency
An ABI of 0.45 indicates severe peripheral arterial disease; revascularization must be considered before HBO therapy can be effective.
Question 4: When evaluating a patient for HBOT, a transcutaneous oxygen measurement (TcPO2) of what value at the wound site best predicts a favorable response to therapy?
- Less than 20 mmHg on room air
- Greater than 200 mmHg during hyperbaric oxygen at treatment pressure
- 20–40 mmHg on room air with a rise to above 100 mmHg during HBO (Correct answer)
- Any value above 40 mmHg on room air
Correct answer: 20–40 mmHg on room air with a rise to above 100 mmHg during HBO
A periwound TcPO2 of 20–40 mmHg on room air that rises above 100 mmHg during HBO (the 'challenge test') predicts a favorable wound healing response.
Question 5: A patient receiving HBO for a diabetic foot ulcer suddenly reports visual changes and facial twitching after 40 minutes at 2.4 ATA. What is the immediate priority?
- Remove the oxygen mask and switch to air breathing (Correct answer)
- Increase depth to 3.0 ATA to stop bubble formation
- Decompress immediately to 1.0 ATA and terminate the session
- Administer IV diazepam and continue the treatment
Correct answer: Remove the oxygen mask and switch to air breathing
These are prodromal signs of central nervous system oxygen toxicity; immediately switching to air breathing typically aborts the progression to seizure.
Question 6: Which patient characteristic is MOST likely to require modification of standard US Navy Treatment Table 6 during management of decompression sickness?
- Age over 60 years
- History of patent foramen ovale
- Concomitant pulmonary oxygen toxicity signs (Correct answer)
- BMI greater than 30
Correct answer: Concomitant pulmonary oxygen toxicity signs
Signs of pulmonary oxygen toxicity (burning chest pain, decreased vital capacity) require air breaks or table extensions to prevent further injury while still treating DCS.
Question 7: A patient is cleared for HBO but reports taking disulfiram (Antabuse). Why is this medication a concern in hyperbaric practice?
- It increases the risk of arterial gas embolism
- It may inhibit superoxide dismutase, reducing antioxidant defense and increasing O2 toxicity risk (Correct answer)
- It causes vasoconstriction that limits oxygen delivery to tissues
- It reacts with high-pressure oxygen to form toxic metabolites
Correct answer: It may inhibit superoxide dismutase, reducing antioxidant defense and increasing O2 toxicity risk
Disulfiram inhibits superoxide dismutase, impairing the body's defense against oxygen free radicals and potentially increasing susceptibility to oxygen toxicity.
CHS Patient Evaluation & Treatment Protocols 2
A patient with a tympanic membrane perforation is referred for hyperbaric oxygen therapy.
What is the most appropriate action?