More Than "Just Another Conversion Reaction!" A Case of Hyperventilation Syndrome
Whatever the cause, increased serum pH may lead to a decline of ionized calcium levels by increasing the binding capacity of calcium to serum albumin. Symptoms of hypocalcaemia may be seen parallel to and depending on the speed and intensity of the fall in ionized calcium levels. Breathing of our patient was fast and deep, with arterial blood gas results concordant with respiratory alkalosis. Her total serum calcium level was normal. However, the ionized calcium level was calculated indirectly (we did not have the facility to analyze ionized calcium levels) as 2.5 mg/dl according to the following formula: [protein bound Ca (mg/dl) = (0.8 x albumin) + (0.2 x globulin) +3]. Every 0.1 unit increase in the blood pH causes a 0.2 mg/dl additional decrease in ionized calcium levels.³ Hence, the ionized serum calcium level of our patient was 2.1 mg/dl. 

Tetany is encountered usually at a serum total calcium level of 5 mg/dl and an ionized serum calcium level of 2.5 mg/dl. The essential determinant in the development of symptoms is the ionized fraction. The clinical picture of hyperventilation ensues after a few minutes of rapid and deep ventilation. 

The clinical picture of the patient was evaluated as a hyperventilation syndrome induced by respiratory alkalosis causing a decline of ionized calcium levels. 

The therapeutic approach to hyperventilation syndrome has several stages and/or degrees of intervention: psychological counselling, physiotherapy and relaxation, and finally drug therapy. Depending on the severity of the problem, one or more therapeutic strategies can be chosen Reassurance and breathing into a bag are enough in the treatment. Understandable and satisfactory explanation on the self limiting nature and the cause of the disease should be provided to the patients. Also our treatment strategy for this patient was composed of reassurance and breathing into a bag. In order not to omit more serious causes of carpopedal spasm, we started IV calcium gluconate infusion until we obtained initial results from the laboratory. Her symptoms started to improve with treatment within five minutes and completely recovered after 1 1/2 hours.

Figure 1: Carpopedal spasm at the hand of the patient when admitted to the emergency unit.

 

We conclude that, patients with suspected conversion reaction should be carefully evaluated before referral to higher centers. Appropriate clinical management of hyperventilation syndrome by primary care physicians will lead to an increase in patient satisfaction as well as a decrease of unnecessary patient load to the emergency units and cause economical savings.