Why Psychogenic Hyperventilation may cause Tetany ?
Scenerio:
✓✓A 15 years old school boy presented with breathlessness after having a familial disharmony.He complaints of perioral paresthesia and digital paresthesia.Soon after he developed carpopedal spasm.
∆∆What is the mechanism under this?
We know that by exhalation we expel carbon dioxide from our body.Removing carbon dioxide more such in this case hyperventilation causes Respiratory alkalosis as from carbon dioxide carbonic acid is produced and then hydrogen ion come from it maintains blood pH.Due to alkalosis that is increased pH has an effect on calcium homeostasis.
∆∆What is that?
We know most of the calcium remains bound to proteins specially albumin.And small amount remains in ionised calcium.Due to Increase of pH calcium binding capacity to albumin increased and ultimately there is decreased ionised calcium but total calcium remains unaltered.
This decrease of calcium causes more entry of sodium into the cell producing neuromuscular excitability producing contract of the muscle manifested as tetany.
✓✓Treatment: No Drug is needed.Propper counselling of the patient and patient party is important as the decrease of respiratory rate abolishes the condition!!
(N.B:Please exclude other causes of breathlessness before diagnosis of Psychogenic Hyperventlation,because the condition may cause due to any etiology of breathlessness)
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