Postoperative delirium in the elderly

Early Neurocognitive Function With Propofol or Desflurane Anesthesia After Laser Laryngeal Surgery With Low Inspired Oxygen

PURPOSE

The effects of general anesthetics on cognitive impairment are unclear and complicated. Laser laryngeal surgery (LLS) requires the administration of low levels of oxygen, which may increase the risk of desaturation and brain function impairment. This prospective randomized trial aimed to compare the effects of desflurane and propofol-based general anesthesia on the occurrence of early postoperative cognitive decline in elderly patients undergoing LLS.

METHODS

Seventy-three patients classified as American Society of Anesthesiologists grade I or II and at least 65 years of age were randomly allocated to receive either desflurane-based (Group D) or propofol-based (Group P) anesthesia during LLS. The standard anesthesia protocol was performed, with a bispectral index between 40 and 60 and a mean arterial pressure within 20% of baseline values. Intraoperative regional oxygen saturation values were recorded. Each patient was assessed using the mini-mental state examination (MMSE) test during the preoperative period (baseline), 30 min after extubation in the postanesthesia care unit, and 1, 3, and 24 h after surgery.

RESULTS

MMSE scores improved slightly in both groups compared to baseline during the early postoperative period, but these increases were not statistically significant. No significant differences were identified in MMSE scores between groups. Only three patients (9.6%) in group D and one patient (3.1%) in group P developed cognitive impairment (p = 0.583).

CONCLUSION

Low intraoperative inspired oxygen concentration during short-duration LLS did not reduce early postoperative cognitive function in elderly patients. Desflurane or propofol-based anesthesia had similar effects on early neurocognition after LLS.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:640-646, 2023.

Common postoperative complications after general anesthesia in oral and maxillofacial surgery

Aim and Objectives:

Anesthesia is Greek word meaning loss of sensation, and involves painful invasive procedure to be performed with little distress and no pain to the patient. Postoperative anesthetic complications are very common and duration of surgery is frequently cited as major risk factor for postoperative complications. The recognition and treatment of these complications are important when providing good quality care. The purpose of this study was to evaluate mild, moderate, and severe postoperative complications in patients undergoing maxillofacial surgery under general anesthesia and also determine the safety of general anesthesia in healthy and patients with comorbidities.

Subjects and Methods:

This prospective study was conducted in the oral and maxillofacial surgery department. Two hundred and twenty patients who were operated under general anesthesia were taken in study. All relevant past medical and dental records were noted and were supported by preformulated questionnaire and was filled preoperatively and after surgery to 12 weeks.

Results:

Mild-to-moderate and severe complications were noted. Females showed more complications than males. Most common complications were sore throat, dysphagia, nausea, vomiting, pain, swelling in normal patients, and in patients with comorbidities delayed wound healing, hypertension, and infection were also seen.

Conclusion:

The use of General Anesthesia is considered safe but it has few risks associated with it and past medical conditions should be evaluated preoperatively.

Pharmacological strategies to prevent postoperative delirium: a systematic review and network meta-analysis

Background

Postoperative delirium (POD) is a condition of cerebral dysfunction and a common complication after surgery. This study aimed to compare and determine the relative efficacy of pharmacological interventions for preventing POD using a network meta-analysis.

Methods

We performed a systematic and comprehensive search to identify and analyze all randomized controlled trials until June 29, 2020, comparing two or more pharmacological interventions, including placebo, to prevent or reduce POD. The primary outcome was the incidence of POD. We performed a network meta-analysis and used the surface under the cumulative ranking curve (SUCRA) values and rankograms to present the hierarchy of the pharmacological interventions evaluated.

Results

According to the SUCRA value, the incidence of POD decreased in the following order: the combination of propofol and acetaminophen (86.1%), combination of ketamine and dexmedetomidine (86.0%), combination of diazepam, flunitrazepam, and pethidine (84.8%), and olanzapine (75.6%) after all types of anesthesia; combination of propofol and acetaminophen (85.9%), combination of ketamine and dexmedetomidine (83.2%), gabapentin (82.2%), and combination of diazepam, flunitrazepam, and pethidine (79.7%) after general anesthesia; and ketamine (87.1%), combination of propofol and acetaminophen (86.0%), and combination of dexmedetomidine and acetaminophen (66.3%) after cardiac surgery. However, only the dexmedetomidine group showed a lower incidence of POD than the control group after all types of anesthesia and after general anesthesia.

Conclusions

Dexmedetomidine reduced POD compared with the control group. The combination of propofol and acetaminophen and the combination of ketamine and dexmedetomidine seemed to be effective in preventing POD. However, further studies are needed to determine the optimal pharmacological intervention to prevent POD.

Substitution of propofol for dexmedetomidine in the anaesthetic regimen does not ameliorate the post-operative cognitive decline in elderly patients

Background and Aims:

Post-operative cognitive dysfunction (POCD) is a poorly understood complication particularly observed in elderly patients, with long-term poor outcome. The randomised study was to compare the incidence of POCD in elderly with bispectral index (BIS)-guided intra-operative use of either dexmedetomidine or propofol with sevoflurane.

Methods:

Eighty-seven patients, planned for non-cardiac surgery under general anaesthesia, were included between June 2017 and March 2018. After exclusion of 7 patients, remaining 80 patients were randomised into dexmedetomidine group and propofol group with 40 patients each. In both the groups, BIS-guided anaesthesia was provided. Cognitive function was assessed by an anaesthesiologist using a battery of neuropsychological tests at baseline pre-operatively, third and seventh day after surgery. The data were entered into a Microsoft Excel spreadsheet and analysis was performed using Statistical Package for Social Sciences (SPSS) version 21.

Results:

Propofol group had a non-significant lower incidence of POCD on third day and dexmedetomidine group showed decreased incidence of POCD on seventh day, accompanied by lower anaesthetic requirement (inhalational as well as intravenous) concomitant with delayed emergence with an acceptable BIS value.

Conclusion:

Dexmedetomidine appeared to be anaesthetic sparing as compared to propofol. BIS monitoring for titrating depth of anaesthesia and hence the anaesthetic exposure is an invaluable tool as compared to routine care anaesthesia for reducing POCD. The patients in both groups did not develop significant POCD until the seventh post-operative day.

Dexmedetomidine improves early postoperative neurocognitive disorder in elderly male patients undergoing thoracoscopic lobectomy

Perioperative neurocognitive disorder (PND) is a common complication following thoracic surgery that frequently occurs in patients ≥65 years. PND includes postoperative cognitive dysfunction (POCD) and postoperative delirium (POD). To investigate whether intravenous dexmedetomidine (DEX) is able to improve neurocognitive function in elderly male patients following thoracoscopic lobectomy, a randomized, double-blinded, placebo-controlled trial was performed at the Affiliated Hospital of Inner Mongolia Medical University (Hohhot, China). Patients aged ≥65 years were enrolled and were subjected to thoracic surgery under general anesthesia. A computer-generated randomization sequence was used to randomly assign patients (at a 1:1 ratio) to receive either intravenous DEX (0.5 µg/kg per h, from induction until chest closure) or placebo (intravenous normal saline). The primary endpoint was the result of the Mini-Mental State Examination (MMSE). The secondary endpoints were the results of the Montreal Cognitive Assessment (MoCA) and those obtained with the Confusion Assessment Method (CAM), as well as the incidence of POCD and POD during the first 7 postoperative days. Other observational indexes included sleep quality at night, self-anxiety scale prior to the operation and 7 days following the operation and the visual analogue scale (VAS) score at rest and during movement on the first and third day following the operation. Furthermore, at 6 h following surgery, the MMSE score in the DEX group was significantly higher than that in the saline group. At 6 h and on the first day postoperatively, the MoCA score in the DEX group was significantly higher than that in the saline group. The incidence of POCD and POD in the DEX group was 13.2 and 7.5%, respectively, while that in the saline group was 35.8 and 11.3%, respectively. There was a significant difference in the incidence of POCD between the two groups (P<0.01). In the DEX group, mean sleep quality was increased, whereas the mean VAS was decreased compared with the corresponding values in the saline group. In conclusion, elderly male patients who underwent thoracoscopic lobectomy under continuous infusion of DEX (0.5 µg/kg/h) exhibited a reduced incidence of POCD during the first 7 postoperative days as compared with the placebo group. Furthermore, DEX improved the subjective sleep quality in the first postoperative night, reduced anxiety and alleviated postoperative pain. In addition, it increased the incidence of bradycardia. The present study was registered in the Chinese Clinical Trial Registry (www.chictr.org.cn; registration no. ChiCTR-IPR-17010958).

Derivation and Validation of a Risk Stratification System for Predicting Postoperative Cognitive Impairment

BACKGROUND

To establish and validate a risk stratification scoring system (we name it as PreOp-BFS, which represents Pre-Operative Brain Fragility Score) for postoperative cognitive impairment containing postoperative cognitive dysfunction (POCD) and postoperative delirium (POD) in elderly patients undergoing non-cardiac surgery.

METHODS

We searched for relevant literatures and reviews reported in PubMed and ScienceDirect databases from January 1994 to December 2017. We performed a preoperative risk factor for cognitive impairment in elderly patients (age ≥ 60 years) who underwent non-cardiac surgery, and finally constructed a risk scoring system to predict postoperative cognitive impairment.

RESULTS

The test data included 49 patients with postoperative cognitive impairment and 31 patients without postoperative cognitive impairment. The postoperative risk scale score ranged from 0 to 8 points. The incidence of postoperative cognitive impairment was 16.2%, 62.9% and 96.2% in the low (0-2 scores), medium (3-4 scores) and high (5-8 scores) risk groups, respectively. In addition, the risk of postoperative cognitive impairment was significantly higher in high and medium risk groups than in low risk group. Receiver operating characteristic (ROC) analysis showed that the area under the curve (AUC) of the risk scoring system was 0.862 [95% CI 0.784-0.941].

CONCLUSIONS

The preoperative risk stratification scoring system (PreOp-BFS) established in this study had a good prediction effect, which was helpful for rapid identification and screening of high-risk susceptible patients with early postoperative cognitive impairment, and for performing targeted perioperative prevention.

Emergence agitation: current knowledge and unresolved questions

Emergence agitation (EA), also referred to as emergence delirium, can have clinically significant consequences. The mechanism of EA remains unclear. The proposed risk factors of EA include age, male sex, type of surgery, emergency operation, use of inhalational anesthetics with low blood-gas partition coefficients, long duration of surgery, anticholinergics, premedication with benzodiazepines, voiding urgency, postoperative pain, and the presence of invasive devices. If preoperative or intraoperative objective monitoring could predict the occurrence of agitation during emergence, this would help to reduce its adverse consequences. Several tools are available for assessing EA. However, there are no standardized clinical research practice guidelines and its incidence varies considerably with the assessment tool or definition used. Total intravenous anesthesia, propofol, μ-opioid agonists, N-methyl-D-aspartate receptor antagonists, nefopam, α2-adrenoreceptor agonists, regional analgesia, multimodal analgesia, parent-present induction, and preoperative education for surgery may help in preventing of EA. However, it is difficult to identify patients at high risk and apply preventive measures in various clinical situations. The risk factors and outcomes of preventive strategies vary with the methodologies of studies and patients assessed.This review discusses important outcomes of research on EA and directions for future research.

Perioperative care of geriatric patients

The older population is expected to nearly double across the globe by 2050, and the baby boom cohort is expected to represent at least 20% of the US population by 2030. Geriatric patients will increasingly utilize the health-care system, and therefore surgical and perioperative care must be tailored to this sensitive group given the increased risk for perioperative complications. The literature was reviewed to highlight fundamental components of the preoperative evaluation as well as cardiac, pulmonary, and renal complications. Frailty is a multidimensional process that can lead to the physiologic effects of aging and estimates the risk of perioperative morbidity and mortality better than chronologic age alone. Health-care providers should assess a geriatric patient's cognitive status, decision-making capacity, frailty, advance care planning, medications, and anesthetic approach in a multidisciplinary fashion to ensure optimal care. The risks of postoperative cardiac, pulmonary, and renal complications should be evaluated and optimized preoperatively to reduce the potential for adverse outcomes.

The Erythrocytic Hypothesis of Brain Energy Crisis in Sporadic Alzheimer Disease: Possible Consequences and Supporting Evidence

Alzheimer’s disease (AD) is a fatal form of dementia of unknown etiology. Although amyloid plaque accumulation in the brain has been the subject of intensive research in disease pathogenesis and anti-amyloid drug development; the continued failures of the clinical trials suggest that amyloids are not a key cause of AD and new approaches to AD investigation and treatment are needed. We propose a new hypothesis of AD development based on metabolic abnormalities in circulating red blood cells (RBCs) that slow down oxygen release from RBCs into brain tissue which in turn leads to hypoxia-induced brain energy crisis; loss of neurons; and progressive atrophy preceding cognitive dysfunction. This review summarizes current evidence for the erythrocytic hypothesis of AD development and provides new insights into the causes of neurodegeneration offering an innovative way to diagnose and treat this systemic disease.

Metabolic Abnormalities of Erythrocytes as a Risk Factor for Alzheimer's Disease

Alzheimer's disease (AD) is a slowly progressive, neurodegenerative disorder of uncertain etiology. According to the amyloid cascade hypothesis, accumulation of non-soluble amyloid β peptides (Aβ) in the Central Nervous System (CNS) is the primary cause initiating a pathogenic cascade leading to the complex multilayered pathology and clinical manifestation of the disease. It is, therefore, not surprising that the search for mechanisms underlying cognitive changes observed in AD has focused exclusively on the brain and Aβ-inducing synaptic and dendritic loss, oxidative stress, and neuronal death. However, since Aβ depositions were found in normal non-demented elderly people and in many other pathological conditions, the amyloid cascade hypothesis was modified to claim that intraneuronal accumulation of soluble Aβ oligomers, rather than monomer or insoluble amyloid fibrils, is the first step of a fatal cascade in AD. Since a characteristic reduction of cerebral perfusion and energy metabolism occurs in patients with AD it is suggested that capillary distortions commonly found in AD brain elicit hemodynamic changes that alter the delivery and transport of essential nutrients, particularly glucose and oxygen to neuronal and glial cells. Another important factor in tissue oxygenation is the ability of erythrocytes (red blood cells, RBC) to transport and deliver oxygen to tissues, which are first of all dependent on the RBC antioxidant and energy metabolism, which finally regulates the oxygen affinity of hemoglobin. In the present review, we consider the possibility that metabolic and antioxidant defense alterations in the circulating erythrocyte population can influence oxygen delivery to the brain, and that these changes might be a primary mechanism triggering the glucose metabolism disturbance resulting in neurobiological changes observed in the AD brain, possibly related to impaired cognitive function. We also discuss the possibility of using erythrocyte biochemical aberrations as potential tools that will help identify a risk factor for AD.

Risk Factors for Delirium After Spine Surgery in Extremely Elderly Patients Aged 80 Years or Older and Review of the Literature: Japan Association of Spine Surgeons with Ambition Multicenter Study

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

Spine surgeries in elderly patients have increased in recent years due to aging of society and recent advances in surgical techniques, and postoperative complications have become more of a concern. Postoperative delirium is a common complication in elderly patients that impairs recovery and increases morbidity and mortality. The objective of the study was to analyze postoperative delirium associated with spine surgery in patients aged 80 years or older with cervical, thoracic, and lumbar lesions.

METHODS

A retrospective multicenter study was performed in 262 patients 80 years of age or older who underwent spine surgeries at 35 facilities. Postoperative complications, incidence of postoperative delirium, and hazard ratios of patient-specific and surgical risk factors were examined.

RESULTS

Postoperative complications occurred in 59 of the 262 spine surgeries (23%). Postoperative delirium was the most frequent complication, occurring in 15 of 262 patients (5.7%), and was significantly associated with hypertension, cerebrovascular disease, cervical lesion surgery, and greater estimated blood loss (P < .05). In multivariate logistic regression using perioperative factors, cervical lesion surgery (odds ratio = 4.27, P < .05) and estimated blood loss ≥300 mL (odds ratio = 4.52, P < .05) were significantly associated with postoperative delirium.

CONCLUSIONS

Cervical lesion surgery and greater blood loss were perioperative risk factors for delirium in extremely elderly patients after spine surgery. Hypertension and cerebrovascular disease were significant risk factors for postoperative delirium, and careful management is required for patients with such risk factors.

Incidence and risk factors of postoperative delirium in elderly patients who underwent laparoscopic surgery for colorectal cancer

BACKGROUND

The reported incidence of postoperative delirium (POD) in elderly patients ranges from 6 to 53 %. Several preoperative and operative factors have been reported as risk factors of POD.

AIM

The aim of this study was to determine the incidence of and risk factors for POD in patients with colorectal cancer who had undergone laparoscopic colorectal resection.

METHODS

A total of 311 consecutive patients aged 75 years and older who underwent laparoscopic surgery for colorectal cancer at our department from January 2008 to December 2013 were classified as delirious group (n = 44) and nondelirious group (n = 267). Short-term outcomes and risk factors for POD were analyzed.

RESULTS

POD was diagnosed in 14.1 % of elderly patients with colorectal cancer. Univariate analysis showed that older age, high American Society of Anesthesiology (ASA) score, performance status >2, low prognostic nutrition index (PNI), past history of delirium or dementia, operative approach, Organ/Space SSI, and cardiac or pulmonary disease were significantly associated with POD. Multivariate logistic regression analysis identified older age, past history of delirium or dementia, operative approach, and Organ/Space SSI as four independent risk factors for POD.

CONCLUSIONS

Our results suggest that the risk of POD is associated with older age, past history of delirium or dementia, operative approach, Organ/Space SSI.

Effects of anesthesia type on short-term postoperative cognitive function in obstetric patients following cesarean section

OBJECTIVE

We aimed to compare the effects of general and spinal anesthesia on cognitive functions in pregnant patients undergoing elective cesarean section.

MATERIAL AND METHODS

Seventy-five American Society of Anesthesiology (ASA) I pregnant patients aged 18-40 years who were scheduled to undergo elective cesarean section were divided into three groups. Group sevoflurane (Group S) and Group desflurane (Group D) were administered general anesthesia, whereas Group regional (Group R) was administered spinal anesthesia. Hemodynamic variables, bispectral index, oxygen saturation were measured at baseline, after induction, spinal injection, and during the surgery. Extubation and eye opening time and Aldrete scores were recorded. Mini-mental state examination, Trieger dot test, and clock drawing test were performed one day before the surgery and repeated at the 1(st), 3(rd) and 24(th) h postoperatively.

RESULTS

There was no statistically significant difference among the groups in terms of demographic data and duration of surgery (p>0.05). Durations of anesthesia for Group S, Group R, and Group D were significantly different (p<0.05). Duration of anesthesia for Group R was significantly longer than for Groups S and D (p<0.0001). Aldrete recovery scores and total remifentanil consumption were significantly higher in Group D than in Group S (p<0.05). Extubation and eye opening times were significantly shorter in Group D than in Group S (p<0.01). According to TDT, statistical significance was found among Group S, Group R, and Group D at the 3rd and 24th h postoperatively (p<0.05), and there was a statistically high significant difference in Groups S and R (p<0.0001).

CONCLUSION

We concluded that general anesthesia with sevoflurane or desflurane and spinal anesthesia had no effects on cognitive functions in patients undergoing cesarean operation.

Postoperative Delirium in the Geriatric Patient

Postoperative delirium, a common complication in older surgical patients, is independently associated with increased morbidity and mortality. Patients older than 65 years receive greater than one-third of the more than 40 million anesthetics delivered yearly in the United States. This number is expected to increase with the aging of the population. Thus, it is increasingly important that perioperative clinicians who care for geriatric patients have an understanding of the complex syndrome of postoperative delirium.

Impact of intraoperative hypotension and blood pressure fluctuations on early postoperative delirium after non-cardiac surgery

INTRODUCTION

Postoperative delirium is common in older patients. Despite its prognostic significance, the pathophysiology is incompletely understood. Although many risk factors have been identified, no reversible factors, particularly ones potentially modifiable by anaesthetic management, have been identified. The goal of this prospective cohort study was to investigate whether intraoperative hypotension was associated with postoperative delirium in older patients undergoing major non-cardiac surgery.

METHODS

Study subjects were patients >65 years of age, undergoing major non-cardiac surgery, who were enrolled in an ongoing prospective observational study of the pathophysiology of postoperative delirium. Intraoperative blood pressure was measured and predefined criteria were used to define hypotension. Delirium was measured by the Confusion Assessment Method on the first two postoperative days. Data were analysed using t-tests, two-sample proportion tests and ordered logistic regression multivariable models, including correction for multiple comparisons.

RESULTS

Data from 594 patients with a mean age of 73.6 years (sd 6.2) were studied. Of these 178 (30%) developed delirium on day 1 and 176 (30%) on day 2. Patients developing delirium were older, more often female, had lower preoperative cognitive scores, and underwent longer operations. Relative hypotension (decreases by 20, 30, or 40%) or absolute hypotension [mean arterial pressure (MAP)<50 mm Hg] were not significantly associated with postoperative delirium, nor was the duration of hypotension (MAP<50 mm Hg). Conversely, intraoperative blood pressure variance was significantly associated with postoperative delirium.

DISCUSSION

These results showed that increased blood pressure fluctuation, not absolute or relative hypotension, was predictive of postoperative delirium.

Predictors of Postoperative Cognitive Decline in Very Old Patients With Hip Fracture: A Retrospective Analysis

BACKGROUND

To investigate incidence and predictors of the various postoperative cognitive declines in old patients with hip fracture.

METHODS

This retrospective chart study evaluated 411 patients (age ≥80 years, follow-up 5 years). After exclusion of 82 patients (preexisting dementia or delirium), 70 patients showing either diagnosed postoperative delirium (POD; group 1; N = 18, 5.5%) or an unspecified cognitive dysfunction and behavior (group 2; N = 52, 15.8%) were analyzed and compared with those without any acute postoperative cerebral impairment (control group; N = 259, 78.7%). Medical history, anesthesiological, orthopedic, and rehabilitation data were assessed using the medical database of the hospital information system. Relative ratio was calculated with Fisher exact test: P value Bonferroni corrected ≤.003.

RESULTS

Acute cognitive complications were observed in 70 (21.3%) patients. Our data in group 1 showed that patients with a medical history of stroke (relative risk [RR] = 16.2, P = .0001) or nicotine abuse (RR = 14.4, P = .001) and perioperative surgical bleeding (RR = 6.54, P = .002) are more likely to develop POD. Unspecified cognitive dysfunction and behavior (group 2) was significantly associated with a medical history of stroke (RR = 12.5, P = .0001) and postoperatively with depression (RR = 3.32, P = .001). In the follow-up, significantly more patients in group 1 (55.6%, RR = 21.8, P = .0001) and group 2 (13.5%, RR = 3.88, P = .001) developed dementia as compared to controls (1.9%). Mortality did not differ significantly between the groups (group 1: RR = 1.75, P = .5 and group 2: RR = 0.66, P = 1.0).

CONCLUSION

These data show that various predictors can identify a greater likelihood of developing postoperative cognitive decline in very old patients with hip fracture. Not identifying or labeling of POD limits the opportunity for evaluation, treatment, and planning. Thus, routine cognitive assessments need to be performed in the scope of multidisciplinary orthogeriatric comanagement.

Risk factors for delirium after spine surgery in elderly patients

Objective

Postoperative delirium is a common complication in the elderly after surgery but few papers have reported after spinal surgery. We analyzed various risk factors for postoperative delirium after spine surgery.

Methods

Between May 2012 and September 2013, 70 patients over 60 years of age were examined. The patients were divided into two groups : Group A with delirium and Group B without delirium. Cognitive function was examined with the Mini-Mental State Examination-Korea (MMSE-K), Clinical Dementia Rating (CDR) and Global Deterioration Scale (GDS). Information was also obtained on the patients' education level, underlying diseases, duration of hospital stay and laboratory findings. Intraoperative assessment included Bispectral index (BIS), type of surgery or anesthesia, blood pressure, fluid balance, estimated blood loss and duration of surgery.

Results

Postoperative delirium developed in 17 patients. The preoperative scores for the MMSE, CDR, and GDS in Group A were 19.1±5.4, 0.9±0.6, and 3.3±1.1. These were significantly lower than those of Group B (25.6±3.4, 0.5±0.2, and 2.1±0.7) (p<0.05). BIS was lower in Group A (30.2±6.8 compared to 35.4±5.6 in group B) (p<0.05). The number of BIS <40 were 5.1±3.1 times in Group A, 2.5±2.2 times in Group B (p<0.01). In addition, longer operation time and longer hospital stay were risk factors.

Conclusion

Precise analysis of risk factors for postoperative delirium seems to be more important in spinal surgery because the surgery is not usually expected to have an effect on brain function. Although no risk factors specific to spinal surgery were identified, the BIS may represent a valuable new intraoperative predictor of the risk of delirium.

Lidocaine administration before tracheal extubation cannot reduce post-operative cognition disorders in elderly patients

Background:

Cognitive dysfunction after surgery is common in elderly patients. Many factors such as anesthetic drugs can cause complication in this surgery. Lidocaine is one of the drugs commonly used during anesthesia. So, we designed this study to find out cognitive effect of lidocaine in elderly patients undergoing non-cardiac surgeries.

Materials and Methods:

In this double-blinded clinical trial, we enrolled 70 patients older than 65 years age undergoing urologic or orthopedic surgeries, were divided in two groups. Patients randomly received intravenous lidocaine (1.5 mg/kg) or normal saline in the same volume immediately before extubation. Mini mental state examination (MMSE) test was used to evaluate cognitive state at discharge time, 6 and 24 h after surgery.

Results:

Mean MMSE scores at the time of discharge from recovery room in lidocaine and saline groups were 22.4 ± 4.5 vs. 22.1 ± 4.4, P = 0.755, respectively. It was significantly lower than MMSE before surgery, 6 and 24 h after the operation. The mean MMSE scores and frequency distribution of intensity of cognitive impairments were not significantly different between two groups at different times.

Conclusion:

Bolus intravenous lidocaine before extubation, did not affect cognitive states in elders undergoing non-cardiac surgery. Effect of lidocaine on cardiac surgeries is clear, but in non-cardiac surgeries, lidocaine has no clinical effects. So, more studies with different doses of lidocaine and different assessment methods are recommended.

Unique Aspects of the Elderly Surgical Population: An Anesthesiologist's Perspective

Increasing life expectancies paired with age-related comorbidities have resulted in the continued growth of the elderly surgical population. In this group, age-associated changes and decreased physiological reserve impede the body's ability to maintain homeostasis during times of physiological stress, with a subsequent decrease in physiological reserve. This can lead to age-related physiological and cognitive dysfunction resulting in perioperative complications. Changes in the cardiovascular, pulmonary, nervous, hepatorenal, endocrine, skin, and soft tissue systems are discussed as they are connected to the perioperative experience. Alterations affect both the pharmacodynamics and pharmacokinetics of administered drugs. Elderly patients with coexisting diseases are at a greater risk for polypharmacy that can further complicate anesthetic management. Consequently, the importance of conducting a focused preoperative evaluation and identifying potential risk factors is strongly emphasized. Efforts to maintain intraoperative normothermia have been shown to be of great importance. Procedures to maintain stable body temperature throughout the perioperative period are presented. The choice of anesthetic technique, in regard to a regional versus general anesthetic approach, is debated widely in the literature. The type of anesthesia to be administered should be assessed on a case-by-case basis, with special consideration given to the health status of the patient, the type of operation being conducted, and the expertise of the anesthesiologist. Specifically addressed in this article are age-related cognitive issues such as postoperative cognitive dysfunction and postoperative delirium. Strategies are suggested for avoiding these pitfalls.

Obstructive sleep apnea and incidence of postoperative delirium after elective knee replacement in the nondemented elderly

BACKGROUND

Postoperative delirium, a common complication in the elderly, can occur following any type of surgery and is associated with increased morbidity and mortality; it may also be associated with subsequent cognitive problems. Effective therapy for postoperative delirium remains elusive because the causative factors of delirium are likely multiple and varied.

METHODS

Patients 65 yr or older undergoing elective knee arthroplasty were prospectively evaluated for postoperative Diagnostic and Statistical Manual of Mental Disorders-IV delirium. Exclusion criteria included dementia, mini-mental state exam score less than 24, delirium, clinically significant central nervous system/neurologic disorder, current alcoholism, or any serious psychiatric disorder. Delirium was assessed on postoperative days 2 and 3 using standardized scales. Patients' preexisting medical conditions were obtained from medical charts. The occurrence of obstructive sleep apnea was confirmed by contacting patients to check their polysomnography records. Data were analyzed using Pearson chi-square or Wilcoxon rank sum tests and multiple logistic regressions adjusted for effects of covariates.

RESULTS

Of 106 enrolled patients, 27 (25%) developed postoperative delirium. Of the 15 patients with obstructive sleep apnea, eight (53%) experienced postoperative delirium, compared with 19 (20%) of the patients without obstructive sleep apnea (P = 0.0123, odds ratio: 4.3). Obstructive sleep apnea was the only statistically significant predictor of postoperative delirium in multivariate analyses.

CONCLUSIONS

This is the first prospective study employing validated measures of delirium to identify an association between preexisting obstructive sleep apnea and postoperative delirium.

Does using a femoral nerve block for total knee replacement decrease postoperative delirium?

Background

The effect of peripheral nerve blocks on postoperative delirium in older patients has not been studied. Peripheral nerve blocks may reduce the incidence of postoperative opioid use and its side effects such as delirium via opioid-sparing effect.

Methods

A prospective cohort study was conducted in patients who underwent total knee replacement. Baseline cognitive function was assessed using the Telephone Interview for Cognitive Status. Postoperative delirium was measured using the Confusion Assessment Method postoperatively. Incidence of postoperative delirium was compared in two postoperative management groups: femoral nerve block ± patient-controlled analgesia and patient-controlled analgesia only. In addition, pain levels (using numeric rating scales) and opioid use were compared in two groups.

Results

85 patients were studied. The overall incidence of postoperative delirium either on postoperative day one or day two was 48.1%. Incidence of postoperative delirium in the femoral nerve block group was lower than patient controlled analgesia only group (25% vs. 61%, P = 0.002). However, there was no significant difference between the groups with respect to postoperative pain level or the amount of intravenous opioid use.

Conclusions

Femoral nerve block reduces the incidence of postoperative delirium. These results suggest that a larger randomized control trial is necessary to confirm these preliminary findings.

Preoperative regional cerebral oxygen saturation is a predictor of postoperative delirium in on-pump cardiac surgery patients: a prospective observational trial

Introduction

Postoperative delirium is an important problem in patients undergoing major surgery. Cerebral oximetry is a non-invasive method to detect imbalances in the cerebral oxygen supply/demand-ratio. Low preoperative cerebral oxygen saturation (ScO₂) levels have been associated with postoperative delirium in non-cardiac surgery patients. The present prospective observational study determines the relationship between pre- and intra-operative ScO₂ levels and postoperative delirium in patients undergoing on-pump cardiac surgery.

Methods

After approval of the local ethical committee and written informed consent, N = 231 patients scheduled for elective/urgent cardiac surgery were enrolled. Delirium was assessed by the confusion-assessment-method for the intensive care unit (CAM-ICU) on the first three days after surgery. ScO₂ was obtained on the day before surgery, immediately before surgery and throughout the surgical procedure. Preoperative cognitive function, demographic, surgery related, and intra- and post-operative physiological data were registered.

Results

Patients with delirium had lower pre- and intra-operative ScO₂ readings, were older, had lower mini-mental-status-examination(MMSE) scores, higher additive EuroScore and lower preoperative haemoglobin-levels. The binary logistic regression identified older age, lower MMSE, neurological or psychiatric disease and lower preoperative ScO₂ as independent predictors of postoperative delirium.

Conclusions

The presented study shows that a low preoperative ScO₂ is associated with postoperative delirium after on-pump cardiac surgery.

Long-term post-operative cognitive decline in the elderly: the effects of anesthesia type, apolipoprotein E genotype, and clinical antecedents

Cognitive dysfunction in the elderly commonly observed following anesthesia has been attributed to age-related neuronal changes exacerbated by pharmacotoxic effects. However, the extent to which these changes may persist following recovery from surgery is still largely unknown. This study investigates the long-term effects of anesthesia on cognitive functioning after orthopedic surgery in 270 elderly patients over the age of 65 who completed a computerized cognitive battery before and 8 days, 4 and 13 months after surgery. Their performance was compared to those of 310 elderly controls who completed the same neuropsychiatric evaluation at baseline and one-year interval. Multivariate analyses adjusted for socio-demographic variables, depressive symptomatology, vascular pathology as well as baseline cognitive performance. We found early and transient post-operative decline in reaction time and constructional praxis. With regard to long-term changes we observed improvement compared to controls in most verbal tasks (probably due to learning effects). On the other hand, a clear dissociation effect was observed for several areas of visuospatial functioning which persisted up to the 13-month follow-up. This specific pattern of visuospatial deficit was found to be independent of apolipoprotein E genotype and closely resembles what has recently been termed vascular mild cognitive impairment, in turn associated with subtle sub-cortical vascular changes. The observation of only minor differences between persons operated by general and regional anesthesia makes it difficult to attribute these changes directly to the anesthetic agents themselves, suggesting that cognitive dysfunction may be attributable at least in part to peri-operative conditions, notably stress and glucocorticoid exposure.

Brief report: preoperative frailty in older surgical patients is associated with early postoperative delirium

We investigated whether preoperative frailty among older noncardiac surgical patients provides information about the development of postoperative delirium that is in addition to traditional geriatric risk factors. One-third of patients had a frailty score ≥3, which is considered "frail" in others' research. Twenty-five percent of patients developed postoperative delirium, which was measured using the confusion assessment method. Multivariable logistic regression showed that age, activities of daily living dependence, instrumental activities of daily living dependence, and cognitive functioning did not contribute significantly to the prediction of postoperative delirium. Only preoperative symptoms of depression (odds ratio=1.42; 95% confidence interval=1.06-1.91; P=0.018) and the frailty score (odds ratio=1.84; 95% confidence interval=1.07-3.1; P=0.028) were independently associated with the development of postoperative delirium.

Pulmonary pathways and mechanisms regulating transpulmonary shunting into the general circulation: an update

Embolic insults account for a significant number of neurologic sequelae following many routine surgical procedures. Clearly, these post-intervention embolic events are a serious public health issue as they are potentially life altering. However, the pathway these emboli utilize to bypass the pulmonary microcirculatory sieve in patients without an intracardiac shunt such as an atrial septal defect or patent foramen ovale, remains unclear. In the absence of intracardiac routes and large diameter pulmonary arteriovenous malformations, inducible large diameter intrapulmonary arteriovenous anastomoses in otherwise healthy adult humans may prove to be the best explanation. Our group and others have demonstrated that inducible large diameter intrapulmonary arteriovenous anastomoses are closed at rest but can open during hyperdynamic conditions such as exercise in more than 90% of healthy humans. Furthermore, the patency of these intrapulmonary anastomoses can be modulated through the fraction of inspired oxygen and by body positioning. Of particular clinical interest, there appears to be a strong association between arterial hypoxemia and neurologic insults, suggesting a breach in the filtering ability of the pulmonary microvasculature under these conditions. In this review, we present evidence demonstrating the existence of inducible intrapulmonary arteriovenous anastomoses in healthy humans that are modulated by exercise, oxygen tension and body positioning. Additionally, we identify several clinical conditions associated with both arterial hypoxemia and an increased risk for embolic insults. Finally, we suggest some precautionary measures that should be taken during interventions to keep intrapulmonary arteriovenous anastomoses closed in order to prevent or reduce the incidence of paradoxical embolism.

Prescription use disorders in older adults

The number of older adults needing substance abuse treatment is projected to rise significantly in the next few decades. This paper will focus on the epidemic of prescription use disorders in older adults. Particular vulnerabilities of older adults to addiction will be considered. Specifically, the prevalence and patterns of use of opioids, stimulants, and benzodiazepines will be explored, including the effects of these substances on morbidity and mortality. Treatment intervention strategies will be briefly discussed, and areas for future research are suggested.

Assessment of role of perioperative melatonin in prevention and treatment of postoperative delirium after hip arthroplasty under spinal anesthesia in the elderly

CONTEXT

Little is known about the relationship between sedative drugs used preoperatively and postoperative delirium. Melatonin is a drug used to sedate patients preoperatively and is hypothesized by recent works to have a curative effect on postoperative delirium.

AIMS

The incidence of postoperative delirium will be tested if affected by three different sedative drugs including melatonin.

SETTINGS AND DESIGN

Controlled randomized doubleblind study.

PATIENTS AND METHODS

Three-hundred patients aged>65 years scheduled for hip arthroplasty under spinal anesthesia were randomly distributed to one of the four groups. Group 1 (control) received nothing for sedation. Group 2 (melatonin) received 5 mg melatonin. Group 3 (midazolam) received 7.5 mg midazolam. Group 4 (clonidine) received 100 μg clonidine. These medications were given orally at sleep time at night of operation and another dose 90 min before operative time. Patients who developed postoperative delirium received 5 mg of melatonin 9 pm for three successive days in a trial to treat delirium.

STATISTICAL ANALYSIS USED

Statistical analysis was done using the SPSS Software (version 13).

RESULTS

Total of 222 patients completed the study. Percentage of postoperative delirium in the control group was 32.65% (16/49 patients). The melatonin group showed a statistically significant decrease in the percentage of postoperative delirium to 9.43% (5/53 patients). Melatonin was successful in treating 58.06% of patients suffered postoperative delirium (36/62 patients) with no difference between different groups.

CONCLUSIONS

Postoperative delirium is affected with the drug used for preoperative sedation. Melatonin was successful in decreasing postoperative delirium when used preoperatively and in treating more than half of patients developed postoperative delirium when used for three postoperative nights.

The effect of sevoflurane anesthesia on cognitive function and the expression of Insulin-like Growth Factor-1 in CA1 region of hippocampus in old rats

To investigate the effects of sevoflurane on cognitive function in old Sprague-Dawley (SD) rats and the expression of insulin-like growth factor-1 (IGF-1) in CA1 region of hippocampus. Forty Sprague-Dawley rats of 12 months old were randomly divided into five groups: the normal control group; 1.5% sevoflurane I group (be tested after received 1.5% sevoflurane for 1 day); 1.5% sevoflurane II group (be tested after received 1.5% sevoflurane for 7 day); 3.0% sevoflurane I group (be tested after received 3.0% sevoflurane for 1 day) and 3.0% sevoflurane II group (be tested after received 3.0% sevoflurane for 7 day). All SD rats were received 1.5 or 3.0% sevoflurane in a special glass anesthesia box for 2 h respectively, except for the normal control group. Y-maze was used to test the ability of learning and memory after being received sevoflurane for 1 or 7 days at the same moment portion. The altered expression level of IGF-1 in the hippocampus was tested to compare its transcripts by RT-PCR analysis. The results showed that 3% sevoflurane induced the decline of cognitive function and significantly deceased the IGF-1 expression at mRNA levels at 1 day in the 3.0% sevoflurane I group when compared with the normal control group. However, there were no significant difference among the other groups when compared with normal control group. Therefore, administration of sevoflurane might temporally affect the ability of cognitive function of rats through suppressing the IGF-1 expression at mRNA levels in hippocampus.

Risk factors for postoperative delirium in elderly patients with colorectal cancer

AIMS

The aim of this retrospective study is to examine risk factors for postoperative delirium in elderly patients with colorectal cancer.

METHODS

The study subjects were patients aged 71 years and older who underwent open surgery (OS) or laparoscopically assisted surgery (LAS) for colorectal cancer from January 2004 to December 2007. Preoperative evaluation, operative factors, morbidity, and mortality were analyzed using the Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity (POSSUM) and Prognostic Nutritional Index (PNI). Delirium was diagnosed by the Confusion Assessment Method (CAM).

RESULTS

Postoperative delirium was diagnosed in 10.9% of elderly patients with colorectal cancer. Age, American Society of Anesthesiologists (ASA) score, and PNI were significantly higher in patients with delirium than those without (P < 0.05, each). Postoperative delirium occurred more frequently in patients with encephalopathy than in those without (P = 0.003). Logistic regression analysis identified PNI and encephalopathy as two independent risk factors for postoperative delirium.

CONCLUSIONS

Preoperative evaluation of nutritional status is important in elderly patients with colorectal cancer in order to prevent postoperative delirium.

A history of alcohol dependence increases the incidence and severity of postoperative cognitive dysfunction in cardiac surgical patients

Postoperative cognitive dysfunction (POCD) commonly occurs after cardiac surgery. We tested the hypothesis that a history of alcohol dependence is associated with an increased incidence and severity of POCD in male patients undergoing cardiac surgery using cardiopulmonary bypass. Recent verbal and nonverbal memory and executive functions were assessed before and one week after surgery in patients with or without a history of alcohol dependence. Cognitive function was significantly reduced after cardiac surgery in patients with versus without a history of alcohol dependence. The results suggest that a history of alcohol dependence increases the incidence and severity of POCD after cardiac surgery.

Does postoperative delirium limit the use of patient-controlled analgesia in older surgical patients?

BACKGROUNDPostoperative pain Is an independent predictor of postoperative delirium. Whether postoperative delirium limits patient-controlled analgesia (PCA) use has not been determined.

METHODS

The authors conducted a nested cohort study in older patients undergoing noncardiac surgery and used PCA for postoperative analgesia. Delirium was measured by using the Confusion Assessment Method. The authors computed a structural equation model to determine the effects of pain and opioid consumption on delirium status and the effect of delirium on opioid use.

RESULTS

Of 335 patients, 108 (32.2%) developed delirium on postoperative day (POD) 1, and 120 (35.8%) on POD 2. Postoperative delirium did not limit the use of PCA. Patients with postoperative delirium used more PCA in a 24-h period (POD 2) compared to those without delirium (mean dose of hydromorphone +/- SE adjusted for covariates was 2.24 +/- 0.71 mg vs. 1.25 +/- 0.67 mg, P = 0.02). Despite more opioid use, patients with delirium reported higher Visual Analogue Scale scores than those without delirium (POD 1: mean visual analog scale +/- SE at rest 4.2 +/- 0.23 vs. 3.3 +/- 0.22, P = 0.0051; POD 2: 3.3 +/- 0.23 vs. 2.5 +/- 0.19, P = 0.004). Path coefficients from structural equation model revealed that pain and opioid use affect delirium status, but delirium does not affect subsequent opioid dose.

CONCLUSIONS

Postoperative delirium did not limit PCA use. Despite more opioid use, visual analog scale scores were higher in patients with delirium. Future studies on delirium should consider the role of pain and pain management as potential etiologic factors.

Identification of a fluorescent general anesthetic, 1-aminoanthracene

We identified a fluorophore, 1-aminoanthracene (1-AMA), that is anesthetic, potentiates GABAergic transmission, and gives an appropriate dissociation constant, K(d) approximately 0.1 mM, for binding to the general anesthetic site in horse spleen apoferritin (HSAF). 1-AMA fluorescence is enhanced when bound to HSAF. Thus, displacement of 1-AMA from HSAF by other anesthetics attenuates the fluorescence signal and allows determination of K(d), as validated by isothermal titration calorimetry. This provides a unique fluorescence assay for compound screening and anesthetic discovery. Additional electrophysiology experiments in isolated cells indicate that 1-AMA potentiates chloride currents elicited by GABA, similar to many general anesthetics. Furthermore, 1-AMA reversibly immobilizes stage 45-50 Xenopus laevis tadpoles (EC(50) = 16 microM) and fluorescence micrographs show 1-AMA localized to brain and olfactory regions. Thus, 1-AMA provides an unprecedented opportunity for studying general anesthetic distribution in vivo at the cellular and subcellular levels.

Neuropsychiatric consequences of coronary artery bypass grafting and noncardiovascular surgery

This paper rewiews findings regarding short- and long-term neuropsychiatnc consequences of coronary artery bypass grafting (CABG) and noncardiac surgery. Stroke is one of the potentially most serious complications of CABG; studies have identified some demographic and medical risk factors. Short-term neuropsychological deficits are common after CABG, but have been similarly documented in noncardiac surgery patients, and may therefore not be specific to this procedure. Neuropsychological deficits in some cognitive areas may persist over time. Patients with depression before surgery are likely to have persistent depression afterwards. Also, depression does not account for the cognitive decline after CABG. Conflicting findings, and the possible methodological limitations of current published studies, are presented and discussed.

Management of anaesthesia in elderly patients

Increasing numbers of very elderly patients require surgery. Elderly patients are at increased risk of perioperative morbidity and mortality because of the high incidence of co-existing age-related diseases. With greater experience, outcomes from major operations in octogenarians have improved. The increased risks of surgery in the elderly must, however, be individually weighed against the benefits to be gained from symptom relief and improved quality of life.

An evaluation strategy for the early detection of postoperative delirium

The aim of the present study was to identify clinical signs detective of the postoperative delirium at the early stage for nursing management. A total of 66 inpatients undergoing cardiac surgery were interviewed using the Delirium Rating Scale (DRS) and NEECHAM Confusion Scale (NCS) preoperatively and on days 1 and 3 postoperatively. The mean onset of delirium occurred on postoperative day 1.3. Development of delirium was detected early by cognitive impairments in the DRS subscales of perceptual disturbance, hallucination, and cognitive status, and the NCS subscales of attention, command, orientation, and verbal skill. These results suggest that assessment of cognitive status on postoperative day is an important strategy in the early detection of postoperative delirium.

Effect of general anesthetics on amyloid precursor protein and mRNA levels in the rat brain

The incidence of Alzheimer's disease is elevated after exposure to surgical interventions. Since amyloid precursor protein (APP) and its neurotoxic derivatives play key roles in the development of Alzheimer dementia, the role of general anesthesia is controversial in the development of cognitive decline. As such, the effect of anesthetics on APP protein and mRNA levels was assessed utilizing semiquantitative Western-immunoblot and reverse transcription polymerase chain reaction (RT-PCR) in brains of rats following intraperitoneal treatment with propofol and thiopental. The anesthetics did not change cortical APP protein and mRNA concentration considerably. These results indicate that both propofol and thiopental are considered to be relatively safe with respect to APP metabolism.

[Cognitive dysfunction after abdominal surgery in elderly patients]

Elderly patients often suffer from postoperative cognitive deficits (POCD) after serious surgical operations. The reasons for this are not well understood. We investigated the influence of the invasiveness of the operation and the duration of the operation as well as the patient's preoperative physical status on measures of cognitive dysfunction. In a prospective study 59 elderly patients (mean age 69.2 years) were subjected to a neuropsychological test battery and a questionnaire following an abdominal surgical operation. The postoperative recovery with a focus on memory function was assessed using the Wechsler Memory Scale (WMS) seven days after the operation. Self-reported cognitive deficits were studied using the a questionnaire of experienced attention deficits (FEDA) three months after the operation. Postoperative psychological and self-reported test results varied as a function of the invasiveness and the duration of the operation. After more invasive operations patients reported a stronger deficit in activities of daily living and a reduction in drive than after less invasive operations. In addition, the duration of anesthesia influenced the experienced deficits. The self-reported deficits were more strongly influenced by the features of the operation than the psychological test data. The physical status of the patients according to the American Society of Anesthesiologists (ASA) along with the duration of anesthesia as covariate was identified as a good predictor for the cognitive recovery post operation.

Managing delirium and agitation in elderly hospitalized orthopaedic patients: Part I--Theoretical aspects

Managing behavioral disorders such as delirium and agitation while simultaneously attending to the acute needs of elderly patients is a challenge that confronts orthopaedic nurses on a daily basis. This will only increase in frequency and complexity as the new century dawns. Delirium and agitation affect morbidity, mortality, length of stay, and costs--in short, outcomes. To manage and care for these patients, orthopaedic nurses must first update their knowledge of acute disorders that can disrupt mental status and behavior, and the effects of systemic events on brain function. With the knowledge of the pathophysiology of delirium and agitation, nurses then need to refine their assessment and intervention skills. This article describes the phenomena of agitation and delirium in the elderly acute orthopaedic patient, outlines current perceptions regarding pathophysiology, and offers guidelines for prevention and intervention. An algorithm has been developed that can assist with the identification of at-risk individuals, causes of delirium, and early assessments in the acute care setting.

Drug-induced delirium. Incidence, management and prevention

Drugs may be the most frequent single cause of delirium, and very often they are a critical element in a multifactorial aetiology. While delirium may be precipitated by virtually any drug, certain classes of drugs are more commonly implicated. Effective management of drug-induced delirium involves recognition, cessation or dosage reduction of the causative drug(s), and initiation of reorientation strategies and supportive medical care. Specific "antidotes' are appropriate in only a few limited cases. Drug treatment aimed at sedation should be introduced for specific indications, such as aggression, risk of harm to self or others, hallucinations, patient distress, and where compliance with therapy or procedures is essential. Certain benzodiazepines (diazepam, lorazepam, midazolam) and/or haloperidol may be the most appropriate choices in these circumstances. Primary prevention requires the prescription of alternative lower risk medications and the minimisation of polypharmacy. Secondary prevention may be achieved through improved recognition of the condition.

Neurological and psychiatric adverse effects of anaesthetics: epidemiology and treatment

The practice of anaesthesia has changed considerably over the past 20 to 30 years owing largely to technological advances in patient monitoring and an expanded and improved pharmacological repertoire. While patient safety in anaesthesia has greatly improved, the risk of neurological and psychiatric adverse effects of anaesthetics remains and is the focus of continued investigation. For example, a great deal of attention has recently been directed at intraoperative awareness. This adverse event can be caused by delivering an inappropriate amount or type of anaesthetic. Another risk of anaesthesia involves drug-induced unpleasant subjective states in patients. Those drugs most frequently associated with these states include ketamine, droperidol and scopolamine. This risk can often be attenuated by careful adjustment of drug dose and the use of adjunctive agents such as benzodiazepines which may produce amnesia of the unpleasant subjective state. While it is well established that modern anaesthetic drugs cause acute impairment of cognition and psychomotor functioning, there is little evidence that these drugs have long term impairing effects. Finally, a particular kind of surgery, cardiac surgery requiring cardiopulmonary bypass, can be associated with adverse neurological and psychiatric sequelae which, while not directly related to anaesthesia, are of intense interest to anaesthesiologists.