Matthew C. Frise, Hung-Yuan Cheng, Annabel H. Nickol, M. Kate Curtis, Karen A. Pollard, David J. Roberts, Peter J. Ratcliffe, Keith L. Dorrington, Peter A. Robbins
Study recruitment flow diagram.
During the period of recruitment there were 25 expressions of interest from deferred blood donors and 126 responses to advertisements for healthy volunteers. In total, 16 participants were enrolled to the IR group and 15 to the ID group. Two female participants in the ID group were withdrawn during the first hypoxic exposure. The first developed headache and nausea consistent with altitude sickness. The second experienced vasovagal syncope. Both recovered promptly without sequelae on return to air. One participant in the IR group had echocardiographic data during hypoxia that precluded accurate measurement of PASP, despite a successful screening visit. No suitable ID participants presented themselves as matches for 2 young males recruited to the IR group early in the course of the study; data for these individuals were not analyzed. Thus, 13 ID individuals completed the study and were matched with an equal number of IR controls in the per-protocol analysis; there were no missing data.