Incidence and risk factors for cognitive dysfunction in patients with severe systemic disease.

OBJECTIVE: To determine the relevance of surgery and other causative factors to the incidence of postoperative cognitive dysfunction (POCD) in patients with severe systemic disease. METHODS: This observational study included 107 noncardiac surgical patients and 26 nonsurgical control subjects, all of whom had an American Society of Anesthesiologists physical classification status of 3. Cognitive assessment was performed preoperatively and 7 days postoperatively, or with a 7-day interval for the control group. POCD was calculated as a combined Z-score. Mini Mental State Examination (MMSE) was used to exclude patients with pre-existing cognitive deficit (MMSE score ≤ 23). Surgical and other factors including duration of surgery/anaesthesia and length of stay in the intensive care unit (ICU) were recorded. RESULTS: After 7 days, POCD was found in 40/107 (37.4%) surgical patients compared with 4/26 (15.4%) nonsurgical controls. Preoperative MMSE score, duration of surgery/anaesthesia, and length of stay in the ICU and hospital were associated with POCD. Logistic regression analysis revealed that preoperative MMSE score was an independent predictor of POCD. CONCLUSION: Lower baseline MMSE score was the only independent predictor for POCD in patients with severe systemic disease.

Documented intraoperative hypotension according to the three most common definitions does not match the application of antihypotensive medication.

This observational study investigated which of the three most common definitions of intraoperative hypotension (IOH), reported in a published systematic literature review, were associated best with anaesthetists' administration of antihypo tensive medication (AHM). IOH and AHM use in anaesthetic procedures in a mixed surgical population (n = 2350) were also reviewed. The definitions were: arterial systolic blood pressure (SBP) < 100 mmHg or a fall in SBP of > 30% of the preoperative SBP baseline; arterial SBP < 80 mmHg; a fall in SBP of > 20% of the preoperative SBP. Accuracy of predicting AHM using these three definitions was 67%, 54% and 65%, respectively. Prediction by a new fourth definition, using an optimal threshold of minimal SBP falling to < 92 mmHg or by > 24% of preoperative baseline, was 68% accurate. In multivariate logistic analysis, age, volatile versus intravenous anaesthetics, medical history of arterial hypertension and all four definitions of IOH were associated with intraoperative AHM, however IOH was not associated with postoperative in-patient stay. The three original definitions correlated poorly with the anaesthetist's judgement about applying AHM. Anaesthetists make complex decisions regarding the relevance of IOH, considering various perioperative factors in addition to SBP. Age, physical status and duration and type of surgery showed better correlations with postoperative in-patient stay than IOH.