Hyperventilation in normal subjects. A clinical, gas-analytic and EMG study.

Clinical (paresthesiae and Trousseau's sign), EMG, blood biochemical (lactic acid and total Ca2+) and gas-analytic (pH, PCO2, PO2, HCO3) changes were studied during and after 5 min voluntary hyperventilation (HV) in 15 normal subjects. Paresthesiae and spontaneous motor activity were common manifestations (87% and 67% respectively) in our test. They were significantly related only to changes in pH, PCO2 and PO2, with paresthesiae arising earlier and at milder gas-analytic changes than motor activity. Paresthesiae and motor activity induced by HV cannot be used as reliable indicators of pathology. Their presence simply reflects the degree of the blood gas-analytic changes (pH, PCO2 and PO2) which therefore should be carefully monitored before drawing any conclusion from an HV test.