[Massive acute hypotonic hyperhydration following arthroscopic synovectomy]

We report the case of a 4 year old boy who developed a massive water intoxication as a complication during knee arthroscopy. The sodium plasma concentration dropped to 100 mmol/l postoperatively. This complication may be triggered by prolonged surgery time, excessive intra-articular pressure, capsular tears and low body weight. To prevent massive incorporation of hypoosmolar fluid, the inflation of a tourniquet as well as the use of NaCl 0,9% as irrigation fluid seems to be of advantage. The guidelines for replacing sodium in hyponatremia are discussed according to literature. In general, hyponatremia should be corrected in the same amount of time as it took for it to develop.