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

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.