[Postoperative mental confusion in the elderly with hip fracture. Perioperative risk factors]

To determine the incidence of postoperative mental confusion and perioperative risk factors in elderly patients with femoral neck fractures.

A prospective study of patients 65 years of age or older undergoing surgery for hip fracture with intradural anesthesia between March 1992 and August 1993. Although the total number of cases came to 162, only 50 patients were enrolled in the study: the rest were excluded mainly because of mental deficits presenting before surgery. Folstein's Mini-Mental State test was used to assess mental function. Risk factors analyzed were classified as preoperative, intraoperative (in the operating room and the recovery room) or postoperative (hospital ward).

Eleven (22%) patients showed signs of postoperative mental confusion. Simple analysis revealed a correlation between mental confusion and ASA (p = 0.01), neuropsychiatric history (p = 0.03) and preoperative hemoglobulin, red blood cell and urea nitrogen levels (p = 0.02). Multifactorial discriminant analysis indicated that patients with low red cell counts before surgery, high urea nitrogen and neuropsychiatric histories were more predisposed (p = 0.004) to mental confusion.

A high incidence of postoperative mental confusion is associated to pre-surgical factors. We therefore suggest that greater preventive and therapeutic efforts be directed preferably to preparation before surgery, especially in patients at high risk.