Contraindications for hyperbaric oxygen therapy consist of all of the following, except:

(Answer to Q. 1)  ANS: D
If pneumothorax occurs during hyperbaric treatment, chest tubes should be immediately inserted; failure to treat pneumothorax can have dire consequences. Gas-trapping can result in barotraumas for those with obstructive bronchial diseases. Similarly, patients who have upper respiratory in-fections and nasal congestion are usually unable to clear their ears during compression and de-compression and thus are prone to eardrum rupture during treatment.

(Answer to Q. 2)  ANS: A
Transcutaneous monitoring has proven to be valuable in the assessment of the overall oxygena-tion status of a patient undergoing hyperbaric therapy. Arterial blood gas monitoring can provide information on the oxygenation status of patients receiving hyperbaric therapy and can also give an indication of their ventilatory status.

(Answer to Q. 3)  ANS: A
The therapeutic dose of nitric oxide is 2 to 80 ppm.

(Answer to Q. 4)  ANS: B
Formula: PAO2 = (PB  PH2O) FIO2  PaCO2 (1.25).
PAO2 = (760  47) 0.80  68 (1.25).
PAO2 = 570.4  85.
PAO2 = 485.4 mm Hg.

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