The acid base status of a patient reveals a pH=7.46 and pCO2=30 mm Hg. The patient has a paially compensated primary-

Respiratory alkalosis Respiratory alkalosis develops when there is a period of sustained hyperventilation, resulting in a reduction of PCO2 and increase in plasma pH. If the condition is sustained, renal compensation occurs, such that tubular acid secretion is reduced and the plasma bicarbonate falls. Respiratory alkalosis is usually of sho duration, occurring in anxiety states or as the result of over-vigorous assisted ventilation. It can be prolonged in the context of pregnancy, pulmonary embolism, chronic liver disease, and ingestion of ceain drugs such as salicylates that directly stimulate the respiratory centre in the brainstem. Clinical features are those of the underlying cause but agitation associated with perioral and digital tingling may also occur, as alkalosis promotes the binding of calcium to albumin, resulting in a reduction in ionised calcium concentrations. In severe cases, Trousseau's sign and Chvostek's sign may be positive, and tetany or seizures may develop (p. 663). Management involves correction of identifiable causes, reduction of anxiety, and a period of rebreathing into a closed bag to allow CO2 levels to rise. Ref Davidson 23rd edition pg 367