Reduced Effective Oxygen Delivery and Ventilation with a Surgical Facemask Placed under Compared to over an Oxygen Mask: A Comparative Study

Figure 4

Box and Whisker plots of respiratory rate (RR) measured as breaths per minute computed using capnography with a surgical facemask only, an O₂ mask only, a surgical facemask over an O₂ mask, and a surgical facemask under an O₂ mask. The circles, squares, and triangles represent average values for each of the five subjects in the various mask configurations.