CHS Oxygen Toxicity & Barotrauma Management 1 — Questions and Answers
Question 1: Which organ system is primarily affected by CNS oxygen toxicity during hyperbaric oxygen therapy?
- Brain and central nervous system (Correct answer)
- Lungs and pulmonary vasculature
- Eyes and optic nerves
- Heart and coronary arteries
Correct answer: Brain and central nervous system
CNS oxygen toxicity primarily affects the brain, producing seizures as the most dangerous acute manifestation during HBO therapy.
Question 2: Which symptom represents the 'V' in the VENTIDC mnemonic for early CNS oxygen toxicity warning signs?
- Vomiting
- Visual changes such as tunnel vision (Correct answer)
- Vertigo
- Vasodilation
Correct answer: Visual changes such as tunnel vision
Visual changes, particularly tunnel vision or narrowing of the visual field, are a classic early warning sign of CNS oxygen toxicity represented by 'V' in VENTIDC.
Question 3: Pulmonary (Lorrain Smith) oxygen toxicity is associated with prolonged exposure to a PO2 greater than:
- 0.5 ATA (Correct answer)
- 1.0 ATA
- 2.0 ATA
- 0.21 ATA
Correct answer: 0.5 ATA
Pulmonary oxygen toxicity occurs with prolonged exposure to PO2 greater than 0.5 ATA, causing tracheobronchitis and alveolar damage over time.
Question 4: What is the recommended first action when a patient displays signs of CNS oxygen toxicity during HBO therapy?
- Increase chamber pressure to compress the seizure
- Remove the oxygen mask and have the patient breathe chamber air (Correct answer)
- Administer IV benzodiazepines immediately
- Perform emergency rapid decompression
Correct answer: Remove the oxygen mask and have the patient breathe chamber air
Removing the oxygen mask so the patient breathes chamber air (21% O2) is the first intervention to reduce brain oxygen delivery and interrupt the toxicity.
Question 5: Which physiological condition is a known predisposing factor that significantly increases the risk of CNS oxygen toxicity?
- Mild controlled hypothyroidism
- Hypercapnia (elevated CO2) (Correct answer)
- Mild normocytic anemia
- Well-controlled type 2 diabetes
Correct answer: Hypercapnia (elevated CO2)
Hypercapnia causes cerebral vasodilation, increasing cerebral blood flow and oxygen delivery to the brain, which lowers the seizure threshold for CNS oxygen toxicity.
Question 6: Air breaks during HBO treatment are used primarily to:
- Allow technicians to inspect chamber equipment
- Reduce cumulative oxygen toxicity risk by allowing tissue recovery (Correct answer)
- Enable patient repositioning during long treatments
- Recalibrate the chamber oxygen sensors
Correct answer: Reduce cumulative oxygen toxicity risk by allowing tissue recovery
Air breaks (typically 5 minutes of air breathing between oxygen periods) allow tissues to metabolically recover, significantly reducing cumulative oxygen toxicity risk.
Question 7: The term 'squeeze' in hyperbaric medicine refers to barotrauma affecting:
- Vascular compression during rapid ascent
- Gas-filled body spaces that cannot equalize pressure during compression (Correct answer)
- Excessive cardiac output at depth
- Nitrogen bubble formation in joints
Correct answer: Gas-filled body spaces that cannot equalize pressure during compression
Squeeze describes barotrauma in gas-filled cavities (ears, sinuses, teeth, lungs) when descent/compression occurs faster than the cavity can equalize pressure.
CHS Oxygen Toxicity & Barotrauma Management 1
Which organ system is primarily affected by CNS oxygen toxicity during hyperbaric oxygen therapy?