In hyperventilation

Abnormally fast and deep breathing, the result of either an emotional state or a physiological condition. Emotional causes include acute anxiety and emotional tension, such as in nervous, anxious patients who may have other functional disturbances related to emotional problems. Physiological causes include a rapid decrease in intracranial pressure, other neurologic problems, and metabolic, pulmonary, and cardiovascular conditions.Ref: Ganong&;s Review of Medical Physiology; 24th edition; page no:647