Oxygen Toxicity & Contraindications Flashcards
7 cards from real CHT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
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What is the primary mechanism by which central nervous system (CNS) oxygen toxicity occurs during hyperbaric oxygen therapy?
Answer: Formation of reactive oxygen species causing neuronal damage
CNS oxygen toxicity is primarily caused by reactive oxygen species (free radicals) that overwhelm antioxidant defenses and damage neuronal membranes.
Which of the following is the hallmark presentation of CNS oxygen toxicity during HBO therapy?
Answer: Grand mal (tonic-clonic) convulsions
Grand mal convulsions are the hallmark of CNS oxygen toxicity; though they may be preceded by VENTID-C warning signs, they can also occur without warning.
In the mnemonic VENTID-C used to identify early CNS oxygen toxicity symptoms, the 'V' stands for:
Answer: Vision changes such as tunnel vision
In VENTID-C, V stands for Visual disturbances (tunnel vision), which is an early warning sign of CNS oxygen toxicity preceding convulsions.
What is the generally accepted maximum oxygen partial pressure (PO2) to minimize risk of CNS oxygen toxicity during routine HBO treatments?
Answer: 1.6 ATA (1,216 mmHg)
A PO2 of 1.6 ATA (1,216 mmHg) is the generally accepted ceiling for intermittent HBO exposures to minimize CNS oxygen toxicity risk.
Pulmonary oxygen toxicity (Lorrain Smith effect) results primarily from:
Answer: Progressive lung injury from prolonged exposure to elevated partial pressures of oxygen
The Lorrain Smith effect describes progressive pulmonary injury from prolonged high-oxygen breathing, leading to inflammation, alveolar damage, and decreased vital capacity.
Which of the following is an ABSOLUTE contraindication to hyperbaric oxygen therapy?
Answer: Untreated pneumothorax
Untreated pneumothorax is an absolute contraindication because increasing ambient pressure can convert it to a life-threatening tension pneumothorax.
Air breaks during HBO treatment are administered primarily to:
Answer: Allow the patient to breathe room air and reduce cumulative oxygen toxicity risk
Air breaks allow patients to breathe room air (21% O2) during treatment, reducing the cumulative oxygen dose and lowering the risk of both CNS and pulmonary oxygen toxicity.