To the Editor: In their randomized trial, Dr Cohen and colleagues1 studied the use of high-flow oxygen in the treatment of cluster headache. There are some points of clarification that would help with interpreting the study.First, for all drugs there is a dosing system but for oxygen it can be occult. The fraction of inspired oxygen (F^) is the volume percentage of oxygen that is inhaled and is analogous to the absorbed (not the prescribed) dose for other drugs. Although in the past F_1O_2 was invasively sampled through the trachea, it can be measured noninvasively and calculated by parameters obtained from mass spectro-metry for different breathing systems. Because the main dosing system of normobaric oxygen therapy is F_1O_2, knowing the range of effective F_1O_2 delivered in this trial would allow prescribing oxygen by different breathing systems to treat cluster headache.
展开▼
