The following factors shift the oxygen dissociation curve to the right, except

Oxygen saturation curve Physiology A curve that describes the relationship between Hb O2 saturation and tension; defined by a sigmoid curve which reflects the interaction of the 4 Hb molecules involved in O2 uptake, transport and release; a 'right shift' of the curve indicates ↓ Hb affinity for O2, as occurs in ↓ pH –ie, acidosis, ↑ temperature, ↑ PCO2, while a 'left shift' indicates ↑ O2 affinity with ↑ pH, ↓ temperature, ↓ 2,3 DPG and ↓ PCO2 Right shifts Acidosis, hyperthermia, alveolar hypoventilation, anemia Left shifts Alkalosis, hypothermia, hyperventilation, carboxyhemoglobinemia, hypophosphatemia, ↑ fetal Hb.