Changes in the plasma sodium concentration after minor, moderate and major surgery.
The plasma sodium concentration, [Na]P, falls following major surgery and this fall is exacerbated by the administration of sodium-free or sodium-low intravenous fluids in the postoperative period. As a prelude to prospective, but controlled, studies we observed the range of [Na]P on admission for surgery in 477 patients. In 309 patients the extent of the change in [Na]P by the first postoperative day (delta [Na]) was related to the severity of the operation undergone (minor, moderate or major) and the volume of potentially hypo-osmolar intravenous fluid given. The mean admission [Na]P was significantly lower with increasing severity of proposed operation. A highly significant fall occurred in [Na]P following surgery of every grade; such falls in [Na]P were seen even when no potentially hypo-osmolar fluids were administered. A significant inverse relationship between admission [Na]P and delta [Na] was demonstrated. We conclude that [Na]P falls following surgery of any severity and that such falls occur even when exogenous dilution cannot be implicated as a cause.
Guy
A J
AJ
Department of Surgery, University of Newcastle upon Tyne, UK.
Michaels
J A
JA
Flear
C T
CT
D004630:Emergencies; D006801:Humans; D007010:Hyponatremia / Q000209:etiology; D007262:Infusions, Intravenous; D013511:Minor Surgical Procedures; D009994:Osmolar Concentration; D011183:Postoperative Complications; D011184:Postoperative Period; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood*; D013514:Surgical Procedures, Operative / Q000145:classification / Q000401:mortality
D012964:Sodium; D011188:Potassium