Postoperative delirium in patients with chronic lower limb ischaemia: what are the specific markers?

OBJECTIVES: we determined the incidence and specific markers of postoperative delirium in elderly patients with chronic lower limb ischaemia.

PATIENTS AND METHODS: since April, 1995, 110 patients aged 60 years or older (mean: 71.6+/-6.6 years) who underwent bypass surgery were assessed regarding aetiological factors of delirium: age, sex, dementia, body-mass index, hypertension, diabetes, cerebral disease, laboratory test results, severity of limb ischaemia, type of arterial occlusion, operative time, and blood transfusion.

RESULTS: discriminant analysis showed statistical significance in the following five variables: age >/=70 years; critical limb ischaemia (and/or ankle pressure <40 mmHg); dementia; duration of operation >/=7 hours; low serum albumin. The overall percentage of cases correctly classified was 78.2% (Wilks> Lambda=0.695, p<0.001); the standardized regression coefficients of the five variables were 0.648, 0.500, 0.329, 0.218, and 0.200, respectively. In logistic regression, the regression coefficients for old age and critical limb ischaemia were 2.646 (14.1 of odds ratio; 95% confidence interval, 2.7-72.0) and 1.337 (3.8; 1.3-10.9), respectively.

CONCLUSIONS: the incidence of postoperative delirium in elderly patients with chronic lower-limb ischaemia was as high as 42.3%, and an age of over 70 years and critical limb ischaemia were identified as specific markers, with 14.1 times and 3.8 times the odds of suffering from delirium after bypass surgery.