<prompt> In hyperventilation:P50 and Hb affinity for O2 increasesP50 and Hb affinity for O2 decreasesP50 increases and O2 affinity decreasesP50 decreases and O2 affinity increases  <response>: Hyperventilation washes out CO2 from body, leadng to alkalosis.So, Oxygen hemoglobin dissociation curve will shift to left high affinity, decreasing P50 of hemoglobin.Reference: Ganongs Review of Medical Physiology 24th edition pg 611 