New York State Basic Emergency Medical Technician (EMT-B) Practice Exam

When using a non-rebreather mask with an oxygen reservoir, what is the appropriate liter flow setting?

1. 5 l/min

2. 10 l/min

3. 15 l/min

4. 20 l/min

The correct answer is: 15 l/min

Using a non-rebreather mask with an oxygen reservoir is an effective way to deliver high concentrations of oxygen to a patient who is in respiratory distress or experiencing hypoxia. The appropriate liter flow setting for this mask is typically around 15 liters per minute. This flow rate is necessary to ensure that the oxygen reservoir bag remains inflated during the patient’s inhalation, allowing them to receive a high concentration of oxygen (usually 80-100%). When the flow is set at 15 liters per minute, it compensates for the oxygen that the patient inhales and helps to maintain the reservoir's volume, preventing it from collapsing when the patient breathes in. Setting the liter flow lower than this, such as at 5 or 10 liters per minute, can result in inadequate oxygen delivery and may cause the reservoir bag to deflate, ultimately reducing the effectiveness of the non-rebreather mask. Although a flow of 20 liters per minute may provide a surplus of oxygen, it is generally unnecessary and not typically required for effective therapy via the non-rebreather mask.