title: Audit of changes in serum urea and electrolytes following peri-operative intravenous fluid therapy.
abstract: One thousand and eleven patients discharged from the postoperative recovery ward with intravenous infusions were reviewed in order to audit the extent of assessment of serum urea and electrolytes (U&Es) and the change in serum U&Es over the perioperative period. 69.7% had preoperative U&Es estimation, 42.5% had both a pre- and postoperative estimation and in 5%, only a postoperative estimate was undertaken. 12.2% of patients whose U&Es were measured had an abnormal preoperative serum potassium compared to 17.2% postoperatively (NS). Compared to a preoperative incidence of 13%, more patients (27.3%) had an abnormal postoperative serum sodium (p < 0.0001). There was a tendency towards postoperative hyponatraemia: 10.0% in the preoperative period compared to a postoperative 25.3% (p < 0.0001). More tests were performed in the elderly (83.9% in age > 65 years versus 69% in age 17-64-p < 0.0001) who were more likely to have electrolyte disturbances preoperative hypokalaemia (p < 0.05), postoperative hyperkalaemia (p < 0.05), postoperative hyponatraemia (p < 0.03) and raised serum urea, both pre- and postoperatively (p < 0.0001 and p < 0.0005 respectively). Patients undergoing intraabdominal procedures did not have significantly different peri-operative electrolyte abnormalities. Fewer tests were performed in emergency patients, who were hypokalaemic in the postoperative period compared to elective patients (p < 0.01). There was a higher incidence of preoperative hyponatraemia and raised serum urea in the emergency group (p < 0.001 and p < 0.0002 respectively). Neurosurgical emergencies often had a degree of preoperative hypokalaemia which persisted after surgery (p < 0.0001). Results indicate an increased risk of serum electrolyte abnormalities following peri-operative intravenous fluid therapy. However in the majority of patients, the magnitude of the change is not significant clinically.
authors.affiliation: Department of Anaesthesia & Surgical Intensive Care, Singapore General Hospital, Singapore.
authors.forename: P C
authors.initials: PC
authors.lastname: Ip-Yam
authors.forename: P J
authors.initials: PJ
authors.lastname: Wood
authors.forename: C
authors.initials: C
authors.lastname: Seng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D016009:Chi-Square Distribution; D004573:Electrolytes / Q000097:blood*; D005260:Female; D005440:Fluid Therapy / Q000009:adverse effects*; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care; D011300:Preoperative Care; D012307:Risk Factors; D014508:Urea / Q000097:blood*
chemical_list: D004573:Electrolytes; D014508:Urea