THE EFFECT OF SORBITOL–MANNITOL ABSORPTION ON SERUM SODIUM CONCENTRATION DURING HYSTEROSCOPIC SURGERY

Abstract

Objective To evaluate the effect on serum electrolyte concentrations of sorbitol–mannitol absorption during hysteroscopic surgery. Design The volume of sorbitol–mannitol retained during hysteroscopic surgery and the difference between the preoperative and the postoperative serum sodium concentrations were measured and analysed for correlation. Setting A university‐based hospital. Subjects These were 40 consecutive patients undergoing hysteroscopic resection of submucous fibroid or uterine septum, using a 9‐mm continuous flow resectoscope with loop or needle electrode for high‐frequency cutting and coagulation and a 4% sorbitol–mannitol solution for uterine irrigation. Results The mean volume of infused sorbitol–mannitol solution was 5435 ± 720 ml (mean ± SEM), with a mean fluid deficit of 718 ± 120 ml. The fall in serum sodium concentration correlated positively with the sorbitol–mannitol deficit (r=0.79, P<0.001), and with the total volume of infused sorbitol–mannitol (r=0.45, P<0.01). In 26 patients the sorbitol–mannitol deficit was less than 1000 ml, and in 14 patients it was equal to or higher than 1000 ml. The group with a fluid deficit exceeding 1000 ml had a significantly (P<0.001) higher fall in serum sodium concentration. Type I or type II fibroid patients retained a significantly (P< 0.001) higher volume of sorbitol–mannitol and had a significantly (P<0.005) higher fall in serum sodium concentration than the group of patients who had a septum or a type 0 fibroid resected. The two patients with a type II fibroid resected retained 2000 ml and 3800 ml of sorbitol–mannitol solution. One of them had symptoms of water intoxication and dilutional hyponatraemia, with cerebral and pulmonary oedema, and the other had signs of early pulmonary oedema. Both patients were successfully managed. Conclusions The fall in serum sodium concentration is positively correlated to the sorbitol–mannitol deficit. Type II fibroid patients are at the highest risk of excessive fluid intravasation and consequent dilutional hyponatraemia. A routine postoperative measurement of serum sodium concentration when fluid deficit exceeds 1000 ml is recommended.