CHT Oxygen Toxicity & Contraindications

Question 1

What is the primary mechanism by which central nervous system (CNS) oxygen toxicity occurs during hyperbaric oxygen therapy?

Accepted Answer

Formation of reactive oxygen species causing neuronal damage

Answer

Decreased cerebral blood flow from vasoconstriction

Answer

Hypercapnia from CO2 retention at elevated pressures

Answer

Nitrogen narcosis interfering with neurotransmission

Question 2

Which of the following is the hallmark presentation of CNS oxygen toxicity during HBO therapy?

Accepted Answer

Grand mal (tonic-clonic) convulsions

Answer

Gradual onset of confusion and disorientation

Answer

Sudden loss of consciousness without any warning signs

Answer

Progressive ascending peripheral numbness and tingling

Question 3

In the mnemonic VENTID-C used to identify early CNS oxygen toxicity symptoms, the 'V' stands for:

Accepted Answer

Vision changes such as tunnel vision

Answer

Vomiting

Answer

Vasodilation of cerebral vessels

Answer

Ventricular arrhythmia

Question 4

What is the generally accepted maximum oxygen partial pressure (PO2) to minimize risk of CNS oxygen toxicity during routine HBO treatments?

Accepted Answer

1.6 ATA (1,216 mmHg)

Answer

1.2 ATA (912 mmHg)

Answer

2.0 ATA (1,520 mmHg)

Answer

2.8 ATA (2,128 mmHg)

Question 5

Pulmonary oxygen toxicity (Lorrain Smith effect) results primarily from:

Accepted Answer

Progressive lung injury from prolonged exposure to elevated partial pressures of oxygen

Answer

Acute bronchospasm triggered by cold dry oxygen inhalation

Answer

Oxygen-induced vasoconstriction of the pulmonary microvasculature

Answer

Excess surfactant production by type II pneumocytes

Question 6

Which of the following is an ABSOLUTE contraindication to hyperbaric oxygen therapy?

Accepted Answer

Untreated pneumothorax

Answer

Mild claustrophobia responsive to anxiolytics

Answer

Active treatment with bleomycin chemotherapy

Answer

Uncontrolled but stable diabetes mellitus

Question 7

Air breaks during HBO treatment are administered primarily to:

Accepted Answer

Allow the patient to breathe room air and reduce cumulative oxygen toxicity risk

Answer

Reduce chamber pressure to prevent barotrauma to the ears

Answer

Equalize pressure across the tympanic membrane

Answer

Flush CO2 from the chamber atmosphere