Which of the following is a reason to avoid Continuous Positive Airway Pressure Mask?
  1. PaO2 < 60 mmHg
  2. Conscious, co-operative patient who can maintain lower airway
  3. No improvement on a non-rebreathing mask
  4. Patient in cardiogenic shock

Answer: The answer is (d). The indications for a continuous positive airway pressure mask include a PaO2 of less than 60 mmHg despite the use of a non-rebreathing mask. The most important criteria are that the patient should be conscious and co-operative and able to maintain the lower airway patent. The patient should also be hemodynamically stable.