Preoperative urine-specific gravity and the incidence of complications after hip fracture surgery: A prospective, observational study

Abstract

Background: Mild to moderately severe dehydration is common in the elderly, but its relationship to surgical outcome is unclear.

Objectives: To study the incidence of dehydration prior to hip fracture surgery and its relationship to postoperative complications.

Design: Prospective observational study.

Setting: Operation department and orthopaedic ward at a regional hospital.

Patients: Forty-five patients [median (interquartile range) age 78 (75 to 86) years] undergoing acute hip fracture surgery.

Interventions: A urine sample was taken on admission to the operating theatre. Complications were assessed 2 days postoperatively using a check-list.

Main outcome measures: Dehydration was considered to be present if the urinary specific gravity was 1.020 or higher, indicating renal water conservation. The number and type of postoperative complications were recorded.

Results: Dehydration was present in one third of the patients. Sixty percent of these patients had at least one postoperative complication, whereas the corresponding proportion was 30% in the euhydrated patients (P < 0.01). Only one patient (3%) had more than one complication in the euhydrated group compared with six patients (40%) in the dehydrated group (P < 0.01). Euhydrated patients had a mean of 0.3 postoperative complications per surgery, whereas dehydrated patients scored 1.1 complications (P < 0.015). The higher incidence included confusion, arterial desaturation and cardiovascular events.

Conclusion: Dehydration before surgery nearly quadrupled the number of postoperative complications after hip fracture repair.

Trial registration: clinicaltrials.gov Identifier: NCT 01294930.

Trial registration: ClinicalTrials.gov NCT01294930.