A Retrospective Study Of Early Postoperative Cognitive Dysfunction In Elderly Patients

Postoperative cognitive dysfunction (POCD) is described as some kind of cognitive impairment syndrome, including changes in attention, concentration, memory and ability of solving problem. Long term impairments may result in changes in personality, social integration and cognitive powers and skills. Although POCD is most frequent after cardiac surgery, the prevalence of POCD after noncardiac surgery in older patients is also significant. The risk factors for POCD after noncardiac surgery include the age of the patient, the character and the duration of the operation, and preexisting cognitive impairment. POCD is likely to impair quality of life and constitute a large burden on society when elderly patients prematurely lose their independence. Numerous studies have reported that neurocognitive deficits are associated with heightened mortality, increased length of hospital stay, and discharge to a nursing home. This is linked with a tremendous demand for health-care resources. Because of the magnitude of the clinical problems, serious consideration must be directed toward understanding its etiology and the development of neuroprotective strategies. Despite many years of research, few preventive strategies and no definitive therapeutic options exist for the management of this troublesome clinical problem. This shortcoming may be secondary to an incomplete understanding of the pathophysiology and etiology of cognitive loss after cardiac surgery; a better understanding of the etiology is essential to finding new therapies. Due to its subtle nature, neuropsychological testing is necessary for POCD detection. The interpretation of literature on POCD is difficult because of numerous methodological limitations, particularly the different definitions of POCD and the lack of data from control groups. Up to today, numerous studies have shown a wide variability of the incidence of POCD, which may be related to different sensitivities of the test battery used to assess cognitive function. Thus, the present study was designed to investigate the incidence of early POCD in elderly patients undergoing non-cardiac or cardiac surgery using various test batteries, and to assess the effect of adenosine disodium triphosphate on early postoperative cognitive dysfunction in elderly patients undergoing cardiac surgery in order to choose more sensitive battery and suitable assessment stratergy, risk factors of POCD, and potential drug for amelioration of neurocognitive function in elderly patients.PART 1 Early postoperative cognitive dysfunction in elderly patients undergoing non-cardiac surgery:Methodology, incidence and risk factors 278 patients older than 60 years of age, scheduled for selective non-cardiac surgery under general anesthesia, were selected for this study. Patients who had a history of symptomatic cerebrovascular disease, psychiatric illness, renal disease (CR≥177 mmol/L), or active liver disease, who had less than a seventh-grade education, or who could not read or hear were excluded. Patients were divided into two groups: one group was tested with mini-mental state examination (MMSE) in different time points of preoperative (at base line), 1 day and 3, 5, 7 days postoperatively. The other group was tested with a neurocognitive test battery, including MMSE, digit span test (DSpT), digit symbol test (DSyT), trial making test (TMT) and short story memory test (SSMT), preoperatively and 7 days postoperatively. Define a decrease in performance equal to or greater than 1 SD from the preoperative score on two or more tests to indicate POCD. The results showed that a total of 142 patients completed tests. MMSE scores were increasing with test times and the incidence of POCD in patients was declined accordingly. The incidence of POCD was 15.4% in patients who used MMSE test only at 6 days after operation, compared with 40.6% in patients who used test battery (P < 0.05). POCD was present in 39% patients who preexisted hypertension and 67% patients who preexisted depression, the incidence of POCD was only 5% when these two kinds of patients were excluded. The results indicate that the neurocognitive test battery we used was more effective than MMSE for the assessment of early POCD in elderly patients. Incidence of POCD in elderly patients at 7 d postoperatively was about 40.6% when test battery was used. Preexisting hypertension and depression poses high risk factors for the occurrence of early POCD in elderly patients.PART 2 Effects of adenosine on early postoperative cognitive dysfunction in elderly patients undergoing cardiac surgeryEighty-five patients older than 60 years of age, scheduled for selective cardiac operation, including heart valve replacement via cardiopulmonary bypass and off-pump coronary artery bypass grafting (OP-CABG), were selected for this study. Patients who had a history of symptomatic cerebrovascular disease, psychiatric illness, renal disease (CR≥177 mmol/L), LVEF≤35,or active liver disease, who had less than a seventh-grade education, or who could not read or hear were excluded. Patients were divided into three groups: control, OP-CABG and adenosine groups. Adenosine disodium triphosphate (2 mmol/L) was added into heart arresting solution in adenosine group. Neuropsychological testing was performed with neurocognitive test battery consists of MMSE, DSpT, DSyT, TMT and SSMT at pre-operation, 7 days and 2 weeks after surgery. The results showed that a total of 68 patients completed all tests. POCD was present in 12/27 (44%) patients in control group, 7/20 (35%) patients in OP-CABG group and 6/23 (26%) patients in adenosine group at 7 days after surgery. The incidence of POCD in adenosine group at 7 days after surgery was lower than that in control group (P<0.05). However, the incidence of POCD was not different among three groups at 2 weeks after surgery. The results suggest that it is possible that CPB did not play a risk factor in the present of COPD after cardiovascular surgery. Adenosine could reduce the incidence of POCD in elderly patients undergoing cardiac surgery within 7 days. This finding might have preventive implications in early POCD in elderly patients undergoing cardiac surgery.