Subjects will be instructed to fast starting the night before testing and to refrain from ingesting alcohol or caffeine. Room temperature will be maintained at all time during the study between 21º C and 24° C; restrictive clothing that could interfere with blood flow to the arms, watches or rings or other jewellery on the hands will be removed. The patient will be comfortably seated or allowed to lie down in the study room for at least 15 min to reach a relaxed cardiovascular steady-state.