You are caring for a patient with a history of COAD who is requiring 70% humidified oxygen via a facemask. You are monitoring his response to therapy by observing his colour, degree of respiratory distress and respiratory rate. The patient’s oxygen saturations have been between 95% and 98%. In addition, the doctor has been taking arterial blood gases. What is the reason for this?
Oximeters may be unreliable under certain circumstances, e.g. if tissue perfusion is poor, if the environment is cold and if the patient’s nails are covered with nail polish.
Arterial blood gases should be sampled if the patient is receiving >60% oxygen.
Pulse oximeters provide excellent evidence of oxygenation, but they do not measure the adequacy of ventilation.
Arterial blood gases measure both oxygen and carbon dioxide levels and therefore give an indication ofboth ventilation and oxygenation