CHT Oxygen Toxicity & Contraindications 2 — Questions and Answers
Question 1: Which chemotherapeutic agent is considered a major contraindication to HBO therapy due to significantly increased pulmonary toxicity risk?
- Cisplatin
- Doxorubicin (Adriamycin)
- Bleomycin (Correct answer)
- Methotrexate
Correct answer: Bleomycin
Bleomycin causes pulmonary fibrosis on its own, and HBO therapy dramatically potentiates this pulmonary toxicity, making concurrent use a major contraindication.
Question 2: An HBO patient inside a monoplace chamber suddenly develops facial twitching and lip tremors. The technician's FIRST action should be:
- Increase chamber pressure to suppress the developing seizure
- Switch the patient to air breathing and prepare to decompress the chamber (Correct answer)
- Administer oxygen via non-rebreather mask through the side port
- Notify the physician and continue the treatment while observing closely
Correct answer: Switch the patient to air breathing and prepare to decompress the chamber
Facial twitching and lip tremors are VENTID-C warning signs of CNS oxygen toxicity; the immediate response is to remove the oxygen stimulus and begin safe decompression.
Question 3: Active seizure disorder is classified as which type of contraindication to HBO therapy?
- Absolute contraindication requiring permanent exclusion from all HBO treatment
- Relative contraindication that may be managed with precautions and monitoring (Correct answer)
- No contraindication — seizure history does not affect HBO safety
- Contraindication only for monoplace chambers, not multiplace chambers
Correct answer: Relative contraindication that may be managed with precautions and monitoring
Active seizure disorder is a relative contraindication; HBO can proceed with physician evaluation, optimized seizure management, and heightened monitoring for oxygen toxicity warning signs.
Question 4: Which of the following patients would be at GREATEST risk for CNS oxygen toxicity during an HBO session?
- A well-hydrated patient with well-controlled hypertension
- A patient with a fever of 102°F (38.9°C) and elevated metabolic rate (Correct answer)
- An elderly patient with stable osteoarthritis on NSAIDs
- A patient who received a normal saline IV bolus prior to treatment
Correct answer: A patient with a fever of 102°F (38.9°C) and elevated metabolic rate
Fever increases metabolic rate and lowers the seizure threshold, significantly increasing the risk of CNS oxygen toxicity during HBO therapy.
Question 5: Which medication is considered a major contraindication with HBO therapy because it inhibits superoxide dismutase, potentially worsening oxygen free radical damage?
- Warfarin (Coumadin)
- Disulfiram (Antabuse) (Correct answer)
- Metformin
- Prednisone
Correct answer: Disulfiram (Antabuse)
Disulfiram inhibits superoxide dismutase and other antioxidant enzymes, reducing the body's ability to neutralize reactive oxygen species generated during HBO, dramatically increasing toxicity risk.
Question 6: The earliest measurable pulmonary function change indicating early pulmonary oxygen toxicity is:
- Decrease in forced vital capacity (FVC) (Correct answer)
- Increase in residual volume (RV)
- Decrease in peak expiratory flow rate (PEFR)
- Increase in total lung capacity (TLC)
Correct answer: Decrease in forced vital capacity (FVC)
A decrease in forced vital capacity (FVC) or vital capacity (VC) is the earliest and most sensitive measurable indicator of pulmonary oxygen toxicity.
Question 7: Congenital spherocytosis is a concern in HBO therapy primarily because:
- Abnormally fragile spherocytes are susceptible to hemolysis under increased atmospheric pressure (Correct answer)
- Abnormal hemoglobin prevents adequate dissolved oxygen delivery to tissues
- Spherocytes are preferentially destroyed by oxygen free radicals during HBO
- These patients have impaired immune responses to pressure changes
Correct answer: Abnormally fragile spherocytes are susceptible to hemolysis under increased atmospheric pressure
In congenital spherocytosis, abnormally shaped and fragile red blood cells are susceptible to increased hemolysis when exposed to elevated ambient pressure.
CHT Oxygen Toxicity & Contraindications 2
Which chemotherapeutic agent is considered a major contraindication to HBO therapy due to significantly increased pulmonary toxicity risk?