In Reply:--I appreciate the interest of Butler and Kenny in our method of preoxygenation. [1]We did not intend to imply that this method alone would achieve an optimal alveolar oxygen fraction. However, in patients who refuse placement of a mask on their face, the method we describe is superior to no preoxygenation.

Robert B. Keifer, M.D., Resident, Department of Anesthesiology, Box 238, Health Sciences Center, University of Virginia, Charlottesville, Virginia 22908.

Keifer RB, Stirt JA: Preoxygenation (letter). ANESTHESIOLOGY 1995; 83:429.