Cognitive change affecting patients after anaesthesia and surgery has been recognised for more than 100 yr. Research into cognitive change after anaesthesia and surgery accelerated in the 1980s when ...multiple studies utilised detailed neuropsychological testing for assessment of cognitive change after cardiac surgery. This body of work consistently documented decline in cognitive function in elderly patients after anaesthesia and surgery, and cognitive changes have been identified up to 7.5 yr afterwards. Importantly, other studies have identified that the incidence of cognitive change is similar after non-cardiac surgery. Other than the inclusion of non-surgical control groups to calculate postoperative cognitive dysfunction, research into these cognitive changes in the perioperative period has been undertaken in isolation from cognitive studies in the general population. The aim of this work is to develop similar terminology to that used in cognitive classifications of the general population for use in investigations of cognitive changes after anaesthesia and surgery. A multispecialty working group followed a modified Delphi procedure with no prespecified number of rounds comprised of three face-to-face meetings followed by online editing of draft versions.
Two major classification guidelines Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5) and National Institute for Aging and the Alzheimer Association (NIA-AA) are used outside of anaesthesia and surgery, and may be useful for inclusion of biomarkers in research. For clinical purposes, it is recommended to use the DSM-5 nomenclature. The working group recommends that ‘perioperative neurocognitive disorders’ be used as an overarching term for cognitive impairment identified in the preoperative or postoperative period. This includes cognitive decline diagnosed before operation (described as neurocognitive disorder); any form of acute event (postoperative delirium) and cognitive decline diagnosed up to 30 days after the procedure (delayed neurocognitive recovery) and up to 12 months (postoperative neurocognitive disorder).
BACKGROUND:Although postoperative cognitive dysfunction (POCD) is well described after coronary artery bypass graft (CABG) surgery, a major concern has been that a progressive decline in cognition ...will ultimately lead to dementia. Since dementia interferes with the ability to carry out daily functions, the impact has far greater ramifications than cognitive decline defined purely by a decreased ability to perform on a battery of neurocognitive tests. The authors hypothesized that early cognitive impairment measured as baseline cognitive impairment is associated with an increased risk of long-term dementia.
METHODS:The authors conducted a prospective longitudinal study on 326 patients aged 55 yr and older at the time of undergoing CABG surgery. Dementia was classified by expert opinion on review of performance on the Clinical Dementia Rating Scale and several other assessment tasks. Patients were also assessed for POCD at 3 and 12 months and at 7.5 yr using a battery of neuropsychologic tests and classified using the reliable change index. Associations were assessed using univariable analysis.
RESULTS:At 7.5 yr after CABG surgery, the prevalence of dementia was 36 of 117 patients (30.8%; 95% CI, 23 to 40). POCD was detected in 62 of 189 patients (32.8%; 95% CI, 26 to 40). Due to incomplete assessments, the majority (113 patients), but not all, were assessed for both dementia and POCD. Fourteen of 32 (44%) patients with dementia were also classified as having POCD. Preexisting cognitive impairment and peripheral vascular disease were both associated with dementia 7.5 yr after CABG surgery. POCD at both 3 (odds ratio, 3.06; 95% CI, 1.39 to 9.30) and 12 months (odds ratio, 4.74; 95% CI, 1.63 to 13.77) was associated with an increased risk of mortality by 7.5 yr.
CONCLUSIONS:The prevalence of dementia at 7.5 yr after CABG surgery is greatly increased compared to population prevalence. Impaired cognition before surgery or the presence of cardiovascular disease may contribute to the high prevalence.
Peri-operative neurocognitive disorders are the most common complication experienced by older individuals undergoing anaesthesia and surgery. Peri-operative neurocognitive disorders, particularly ...postoperative delirium, result in long-term poor outcomes including: death; dementia; loss of independence; and poor cognitive and functional outcomes. Recent changes to the nomenclature of these disorders aims to align peri-operative neurocognitive disorders with cognitive disorders in the community, with consistent definitions and clinical diagnosis. Possible mechanisms include: undiagnosed neurodegenerative disease; inflammation and resulting neuroinflammation; neuronal damage; and comorbid systemic disease. Pre-operative frailty represents a significant risk for poor postoperative outcomes; it is associated with an increase in the incidence of cognitive decline at 3 and 12 months postoperatively. In addition to cognitive decline, frailty is associated with poor functional outcomes following elective non-cardiac surgery. It was recently shown that 29% of frail patients died or experienced institutionalisation or new disability within 90 days of major elective surgery. Identification of vulnerable patients before undergoing surgery and anaesthesia is the key to preventing peri-operative neurocognitive disorders. Current approaches include: pre-operative delirium and cognitive screening; blood biomarker analysis; intra-operative management that may reduce the incidence of postoperative delirium such as lighter anaesthesia using processed electroencephalography devices; and introduction of guidelines which may reduce or prevent delirium and postoperative neurocognitive disorders. This review will address these issues and advocate for an approach to care for older peri-operative patients which starts in the community and continues throughout the pre-operative, intra-operative, postoperative and post-discharge phases of care management, involving multidisciplinary medical teams, as well as family and caregivers wherever possible.
Postoperative cognitive dysfunction (POCD) has been documented after cardiac and noncardiac surgery. The type of surgery and anesthetic has been assumed to be associated with the incidence but there ...are few prospective data comparing the incidence after different procedures. In this study, we sought to determine the association of the type of surgical procedure and anesthesia on the incidence of POCD after procedures involving light sedation, general anesthesia for noncardiac surgery, and general anesthesia for cardiac surgery involving cardiopulmonary bypass.
Eight neuropsychological tests were administered at baseline and at 7 days and 3 months postoperatively to subjects from 3 procedure groups and a nonoperative control group. Reliable change index was used to calculate POCD. The study sample consisted of subjects involved in 3 separate trials investigating coronary angiography (CA) (percutaneous diagnostic procedure) under sedation, major noncardiac surgery (total hip joint replacement THJR surgery) under general anesthesia, and coronary artery bypass graft (CABG) surgery under general anesthesia.
Data were collected from 644 patients in the patient groups and 34 subjects in the control group. Neuropsychological results were available for POCD at day 7 for THJR surgery (n=162) and CABG surgery (n=281). The incidence of POCD at day 7 was 17% for THJR surgery and 43% for CABG surgery (adjusted odds ratio=0.2, 95% confidence interval CI: 0.1, 0.4; P<0.01). At 3 months, the incidence of POCD for all groups combined (n=636) was 17% (21% for CA under sedation, 16% for THJR surgery, and 16% for CABG surgery). The mean (95% CI) for the difference in proportions of POCD among groups was 0.00 (-0.07, 0.07) (P=0.91) for CABG versus THJR; -0.05 (-0.12, 0.03) (P=0.21) for CABG versus CA; and -0.05 (-0.13, 0.03) (P=0.24) for THJR versus CA. There were no significant differences among groups (adjusted odds ratio=1.21, 95% CI: 0.94, 1.55; P=0.13).
The incidence of POCD in old and elderly patients at day 7 was higher after CABG surgery than THJR surgery, but POCD at 3 months was independent of the nature or the type of procedure or anesthetic when comparing CA, THJR, and CABG surgery groups. Cardiovascular risk factors were not predictive of POCD after any procedure.
The perioperative inflammatory response may be implicated in adverse outcomes including neurocognitive dysfunction and cancer recurrence after oncological surgery. The immunomodulatory role of ...anesthetic agents has been demonstrated in vitro; however, its clinical relevance is unclear. The purpose of this meta-analysis was to compare propofol and sevoflurane with respect to biomarkers of perioperative inflammation. The secondary aim was to correlate markers of inflammation with clinical measures of perioperative cognition.
Databases were searched for randomized controlled trials examining perioperative inflammation after general anesthesia using propofol compared to sevoflurane. Inflammatory biomarkers investigated were interleukin (IL)-6, IL-10, tissue necrosis factor alpha (TNF-α), and C-reactive protein (CRP). The secondary outcome was incidence of perioperative neurocognitive disorders. Meta-analysis with metaregression was performed to determine the difference between propofol and sevoflurane.
Twenty-three studies were included with 1611 participants. Studies varied by surgery type, duration, and participant age. There was an increase in the mean inflammatory biomarker levels following surgery, with meta-analysis revealing no difference in effect between propofol and sevoflurane. Heterogeneity between studies was high, with surgery type, duration, and patient age contributing to the variance across studies. Only 5 studies examined postoperative cognitive outcomes; thus, a meta-analysis could not be performed. Nonetheless, of these 5 studies, 4 reported a reduced incidence of cognitive decline associated with propofol use.
Surgery induces an inflammatory response; however, the inflammatory response did not differ as a function of anesthetic technique. This absence of an effect suggests that patient and surgical variables may have a far more significant impact on the postoperative inflammatory responses than anesthetic technique. The majority of studies assessing perioperative cognition in older patients reported a benefit associated with the use of propofol; however, larger trials using homogenous outcomes are needed to demonstrate such an effect.
Cognitive change affecting patients after anaesthesia and surgery has been recognised for more than 100 yr. Research into cognitive change after anaesthesia and surgery accelerated in the 1980s when ...multiple studies utilised detailed neuropsychological testing for assessment of cognitive change after cardiac surgery. This body of work consistently documented decline in cognitive function in elderly patients after anaesthesia and surgery, and cognitive changes have been identified up to 7.5 yr afterwards. Importantly, other studies have identified that the incidence of cognitive change is similar after non-cardiac surgery. Other than the inclusion of non-surgical control groups to calculate postoperative cognitive dysfunction, research into these cognitive changes in the perioperative period has been undertaken in isolation from cognitive studies in the general population. The aim of this work is to develop similar terminology to that used in cognitive classifications of the general population for use in investigations of cognitive changes after anaesthesia and surgery. A multispecialty working group followed a modified Delphi procedure with no prespecified number of rounds comprised of three face-to-face meetings followed by online editing of draft versions.Two major classification guidelines (Diagnostic and Statistical Manual for Mental Disorders, fifth edition DSM-5 and National Institute for Aging and the Alzheimer Association NIA-AA) are used outside of anaesthesia and surgery, and may be useful for inclusion of biomarkers in research. For clinical purposes, it is recommended to use the DSM-5 nomenclature. The working group recommends that ‘perioperative neurocognitive disorders’ be used as an overarching term for cognitive impairment identified in the preoperative or postoperative period. This includes cognitive decline diagnosed before operation (described as neurocognitive disorder); any form of acute event (postoperative delirium) and cognitive decline diagnosed up to 30 days after the procedure (delayed neurocognitive recovery) and up to 12 months (postoperative neurocognitive disorder).
Since general anaesthesia invariably accompanies surgery, the contribution of each to the development of postoperative cognitive dysfunction (POCD) has been difficult to identify.
A prospective ...randomized controlled trial was undertaken in elderly patients undergoing extracorporeal shock wave lithotripsy (ESWL). Between 2005 and 2011, 2706 individuals were screened to recruit 100 eligible patients. Patients were randomly assigned to receive general or spinal anaesthesia alone. A battery of eight neuropsychological tests was administered before operation and at 7 days and 3 months after operation. The reliable change index was used to calculate the incidence of POCD. Intention-to-treat analysis was used to compare rates of POCD.
Futility analysis led to stopping of the trial after recruitment of 100 patients. Fifty patients were randomly assigned to general anaesthesia, and 48 patients to spinal anaesthesia without sedation or postoperative opioids. At 3 months, POCD was detected in 6.8% 95% confidence interval (CI): 1.4–18.7% of patients in the general anaesthesia group and 19.6% (95% CI: 9.4–33.9%) in the spinal group (P=0.07). At 7 days after operation, the incidence of POCD was 4.1% (95% CI: 0.5–14%) in the general anaesthesia group and 11.9% (95% CI: 4.0–26.6%) in the spinal group (P=0.16).
We found no significant difference in the rates of POCD when comparing general anaesthesia with spinal anaesthesia, suggesting that the surgical or procedural process itself may contribute to the development of POCD.
Australian Clinical Trials Registry number ACTRN12605000150640.
It is unknown if the type of general anaesthetic used for maintenance of anaesthesia affects the incidence of postoperative cognitive dysfunction (POCD). The aim of this study was to compare the ...incidence of POCD in patients administered either sevoflurane or propofol for maintenance of anaesthesia during total hip replacement surgery. Following administration of a spinal anaesthetic, patients received either sevoflurane (n=121) or propofol (n=171) at the discretion of the anaesthetist for maintenance of general anaesthesia to maintain the processed electroencephalogram (bispectral index, BIS) under 60. POCD was assessed postoperatively at day 7, three months, and 12 months using a neurocognitive test battery. There was no statistically significant difference between the incidence of POCD at any timepoint with sevoflurane compared to propofol. The mean BIS was significantly lower in the sevoflurane group than in the propofol group (mean BIS 44.3 standard deviation, SD, 7.5 in the sevoflurane group versus 53.7 SD 8.1 in the propofol group, P=0.0001). However, there was no statistically significant association between intraoperative BIS level and the incidence of POCD at any timepoint. Our results suggest that the incidence of POCD is not strongly influenced by the type of anaesthesia used in elderly patients.
IMPORTANCE: Anesthesia and surgery are believed to act on the central nervous system by a fully reversible mechanism innocuous to nerve cells. Evidence that neurological sequelae may follow would ...challenge this belief and would thereby suggest a need to reassess theories of the mechanism of anesthetic action or the response of the central nervous system to surgery. OBJECTIVE: To measure 2 biomarkers of neurological injury (neurofilament light and tau) in plasma in a series of timed collections before and after anesthesia and surgery. DESIGN, SETTING, AND PARTICIPANTS: These 2 related observational studies (CAPACITY and ARCADIAN) recruited patients 60 years and older who were undergoing general anesthesia for surgeries performed within a tertiary hospital. Blood samples were taken immediately before surgical anesthesia was administered and then sequentially after surgery at 30-minute, 6-hour, 24-hour, and 48-hour intervals. Sampling took place from January 2014 to August 2015. Data analysis took place from October 2016 to February 2017. MAIN OUTCOMES AND MEASURES: Plasma neurofilament light and tau. RESULTS: A total of 30 patients were enrolled (13 from the CAPACITY study and 17 from the ARCADIAN study). The mean (SD) age was 69.1 (7.0) years, and 18 members (59%) of the participant group were female; 22 (73%) were undergoing joint arthroplasty. Mean neurofilament light increased at each measurement from a combined baseline mean (SD) of 22.3 (20.4) pg/mL to a maximal combined mean (SD) level of 35.1 (28.7) pg/mL, a maximum increase of 67% (95% CI, 45%-89%; P < .001), at 48 hours postoperatively. The level of tau increased significantly from baseline at every measurement, from a combined baseline mean (SD) of 3.1 (1.3) pg/mL to a maximal combined mean (SD) of 10.8 (9.5) pg/mL, a peak increase of 257% (95% CI, 154%-361%; P < .001), at 6 hours postoperatively. After 6 hours, the mean level began to return to baseline but remained elevated after 48 hours. CONCLUSIONS AND RELEVANCE: Neurofilament light is a specific marker of axonal injury and has been shown to indicate neuronal damage in a number of diseases. Tau proteins are an integral component of axonal integrity, and increased tau indicates neuronal damage. The increases in both neurofilament light and tau over 48 hours after surgery suggest that general anesthesia and surgery may be associated with neuronal damage in the short term. Further investigations will be required to study any association with clinical outcomes. These preliminary findings demand that we question the prevailing assumption that anesthesia and surgery are innocuous, transient, and without injurious changes to the central nervous system.
In patients admitted to hospital, preoperative mild cognitive impairment predicts postoperative complications. The effect of mild cognitive impairment on discharge readiness among the day stay ...surgery population is unknown. Our aims were to determine the incidence of impaired cognitive performance at discharge after day stay endoscopy and whether pre-existing mild cognitive impairment was associated with its development. A single-centre cohort study of elective day stay endoscopy patients was undertaken. Over a three-month period, data were collected from 69 patients aged 65 years and over. Patients were cognitively assessed on admission and discharge using the Montreal cognitive assessment tool and the three-minute diagnostic confusion assessment method. At baseline, patients who scored 1.5 or more standard deviations below age-adjusted levels on the Montreal cognitive assessment tool in conjunction with a subjective memory complaint were classified as having mild cognitive impairment. At discharge, patients were classified as having impaired cognitive performance if there was a reduction in the Montreal cognitive assessment tool score by at least two points. We also assessed delirium and subsyndromal delirium at discharge using the three-minute diagnostic confusion assessment method. We identified mild cognitive impairment in 23 patients (33.3%) on admission, and impaired performance on the Montreal cognitive assessment tool test at discharge in 35 (50.7%) patients. There was no association between mild cognitive impairment on admission and impaired cognitive performance at discharge (50.0% versus 51.1%, P1/40.94). This study demonstrates that evidence of impaired cognitive performance on the Montreal cognitive assessment tool testing is present after day stay endoscopy in over 50% of elderly patients, but this is not associated with preoperative cognitive status.
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