J Korean Soc Emerg Med.  1998 Sep;9(3):415-419.

Alteration of Ionized Calcium, Magnesium and Acid-base status in Hyperventilation Syndrome

• Chung SM
• Yoon CJ
• Chang WJ
• Lee HS

Abstract

BACKGROUND: Tetanic spasm is often noted in hyperventilating patients coming in to emergency departments. Classical explanation far this phenomenon was decreased ionized calcium levels due to respiratory alkalosis precipitated by the hyperventilation. Clinically these symptoms were observed in hypocalcemia and were thought as such without doubt. But clinical investigation on the levels of ionized calcium levels have not been clarified. Recent investigations on hyperventilating volunteers have suggested other pathophysiology for tetanic spasm in hyperventilating patients which is the decrement of ionized magnesium level rather than ionized calcium. We wanted to see if these results applied to our hypeventilating patients and see if ionized magnesium level was a factor producing tetanic symptoms. METHOD AND MATERIAL : 35 patients with diagnosis of hyperventilation syndrome by emergency physician were studied retrospectively. Hyperventilating patients arriving at Severance hospital Emergency Center from Jan.1996 to Feb. 1998 were included. Patients with cardiovascular, pulmonary diseases, history of renal or liver disease were excluded. Ion-selective method was used to detect ionized calcium, magnesium levels and arterial blood gas features. Average levels were compared to reference ranges and Wilkoxon-rank. sum test was used to compare hyperventilating patients with tetanic spasm and those with other symptoms such as dyspnea, chest pain and palpitations.
RESULTS
1) Sodium, potassium and chloride levels were 138mmol/L, 3.6mmo1/L, 106mmol/L each which were within a normal range. 2) Degrees of hyperventilation were similar with average of PH 7.54(7.4-7.71), pCO2 23.6mmHg, showing respiratory alkalosis. 3) Ionized calcium and ionized magnesium each showed 0.61mg/dL, 0.16mg/dL lower values than the lowest reference ranges which were 4.5-5.6mg/dL for ionized calcium and 1.19-1.63 for ionized magnesium. 4) No statistical difference points were observed between the tetanic spasm group and group without spasm. Female preponderance were noted in tetanic spasm group.
CONCLUSION
We conclude that ogler than decrement of ionized calcium, decrement of ionized magnesium could be a factor far inducing tetanic spasm in respiratory alkalosis caused by hyperventilation.

MeSH Terms

Alkalosis, Respiratory
Calcium*
Chest Pain
Diagnosis
Dyspnea
Emergencies
Emergency Service, Hospital
Female
Humans
Hydrogen-Ion Concentration
Hyperventilation*
Hypocalcemia
Liver Diseases
Lung Diseases
Magnesium*
Potassium
Reference Values
Retrospective Studies
Sodium
Spasm
Volunteers
Calcium
Magnesium
Potassium
Sodium