Unconsciousness is a fundamental component of general anesthesia (GA), but anesthesiologists have no reliable ways to be certain that a patient is unconscious. To develop EEG signatures that track loss and recovery of consciousness under GA, we recorded high-density EEGs in humans during gradual induction of and emergence from unconsciousness with propofol. The subjects executed an auditory task at 4-s intervals consisting of interleaved verbal and click stimuli to identify loss and recovery of consciousness. During induction, subjects lost responsiveness to the less salient clicks before losing responsiveness to the more salient verbal stimuli; during emergence they recovered responsiveness to the verbal stimuli before recovering responsiveness to the clicks. The median frequency and bandwidth of the frontal EEG power tracked the probability of response to the verbal stimuli during the transitions in consciousness. Loss of consciousness was marked simultaneously by an increase in low-frequency EEG power (<1 Hz), the loss of spatially coherent occipital alpha oscillations (8–12 Hz), and the appearance of spatially coherent frontal alpha oscillations. These dynamics reversed with recovery of consciousness. The low-frequency phase modulated alpha amplitude in two distinct patterns. During profound unconsciousness, alpha amplitudes were maximal at low-frequency peaks, whereas during the transition into and out of unconsciousness, alpha amplitudes were maximal at low-frequency nadirs. This latter phase–amplitude relationship predicted recovery of consciousness. Our results provide insights into the mechanisms of propofol-induced unconsciousness, establish EEG signatures of this brain state that track transitions in consciousness precisely, and suggest strategies for monitoring the brain activity of patients receiving GA.

http://www.pnas.org/content/pnas/110/12/E1142.full.pdf

Electroencephalogram signatures of loss and recovery of consciousness from propofol

The purpose of this guideline is to present evidence-based and consensus-based recommendations for the prevention and treatment of postoperative delirium. The cornerstones of the guideline are the preoperative identification and handling of patients at risk, adequate intraoperative care, postoperative detection of delirium and management of delirious patients. The scope of this guideline is not to cover ICU delirium. Considering that many medical disciplines are involved in the treatment of surgical patients, a team-based approach should be implemented into daily practice. This guideline is aimed to promote knowledge and education in the preoperative, intraoperative and postoperative setting not only among anaesthesiologists but also among all other healthcare professionals involved in the care of surgical patients.

European Society of Anaesthesiology evidence-based and consensus-based guideline on postoperative delirium

Disclosure Information: Disclosures for the members of t Geriatrics Society Postoperative Delirium Panel are listed in Support: Supported by a grant from the John A Hartford Fou to the Geriatrics-for-Specialists Initiative of the American Geri (grant 2009-0079). This article is a supplement to the American Geriatrics Soci Practice Guidelines for Postoperative Delirium in Older Adu at the American College of Surgeons 100 Annual Clinic San Francisco, CA, October 2014.

Postoperative Delirium in Older Adults: Best Practice Statement from the American Geriatrics Society

Fast-track hip and knee arthroplasty.

For patients undergoing coronary-artery bypass grafting (CABG), adverse neurologic outcomes, including stroke and cognitive decline, are major concerns. Even mild cognitive deficits before surgery may be a marker for cerebrovascular disease and increased risk.

Cognitive and neurologic outcomes after coronary-artery bypass surgery.

There is evidence that postoperative cognitive dysfunction (POCD) is a significant problem after major surgery, but the pathophysiology has not been fully elucidated. The interpretation of available studies is difficult due to differences in neuropsychological test batteries as well as the lack of appropriate controls. Furthermore, there are no internationally accepted criteria for defining POCD. This article aims to provide an update of current knowledge of the pathogenesis of POCD with a focus on perioperative pathophysiology and possible benefits achieved from an enhanced postoperative recovery using a fast-track methodology. It is concluded that the pathogenesis of POCD is multifactorial and future studies should focus on evaluating the role of postoperative sleep disturbances, inflammatory stress responses, pain and environmental factors. Potential prophylactic intervention may include minimal invasive surgery, multi-modal non-opioid pain management and pharmacological manipulation of the inflammatory response and sleep architecture.

New insights into the pathophysiology of postoperative cognitive dysfunction

The aim was to explore whether the incidence of tonsillar squamous cell carcinomas (TSCCs) increased in Eastern Denmark, 2000-2010, and whether human papillomavirus (HPV) could explain the increase, and to assess the association of HPV prevalence with gender, age, and origin (i.e., the certainty of tonsillar tumor origin). We applied HPV DNA PCR and p16 immunohistochemistry to all TSCCs registered in the Danish Head and Neck Cancer Group (DAHANCA) and in the Danish Pathology Data Bank (n = 632). Pathologists reviewed and subdivided the tumors into two groups: specified and nonspecified TSCCs. Approximately 10% of HPV-positive tumors was genotyped by amplicon next-generation sequencing. The overall crude incidence of TSCCs increased significantly (2.7% per year) and was explained by an increasing incidence of HPV-positive TSCCs (4.9% per year). The overall HPV prevalence was 58%, with HPV16 being the predominant HPV type. In multivariate analysis, the HPV prevalence was associated with age ( 60 years) (OR, 1.72; 95% CI 1.13-2.63) and origin (nonspecified vs. specified TSCCs) (OR, 0.15; 95% CI 0.11-0.22). The association of HPV prevalence with origin increased over time in specified TSCCs (OR per year, 1.10; 95% CI 1.01-1.19), whereas no change over time was observed among nonspecified TSCCs (OR per year, 0.99; 95% CI 0.90-1.08). In conclusion, the observed increase in the number of HPV-positive TSCCs can explain the increasing number of TSCCs in Eastern Denmark, 2000-2010. HPV prevalence was associated with younger age (<55 years) and a high certainty of tonsillar tumor origin.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/ijc.29254

A high and increasing HPV prevalence in tonsillar cancers in Eastern Denmark, 2000-2010: the largest registry-based study to date.

BACKGROUND:Postoperative cognitive dysfunction (POCD) is reported to occur after major surgery in as many as 20% of patients, elderly patients may especially experience problems in the weeks and months after surgery. Recent studies vary greatly in methods of evaluation and diagnosis of POCD, and the

/pdf/cognitive-dysfunction-after-fast-track-hip-and-knee-47gef9bm8q.pdf

Cognitive dysfunction after fast-track hip and knee replacement.

Postoperative cognitive impairment is an increasingly common problem as more elderly patients undergo major surgery. Cognitive deficits in the postoperative period cause severe problems and are associated with a marked increase in morbidity and mortality. There are two main entities of postoperative cognitive decline, delirium and postoperative cognitive dysfunction, which are often reported as being part of the same continuum. Although there are similarities in the predisposing factors, it seems unlikely that they share the same pathophysiology. Both have multifactorial pathogenesis but differ in numerous other ways, with delirium being well-defined and acute in onset and postoperative cognitive dysfunction (POCD) being subtler and with longer duration. This review aims to provide an overview of the differences in the diagnosis of the two entities and to illustrate the methodological problems that can be encountered when evaluating cognitive deficits postoperatively.

Postoperative delirium and postoperative cognitive dysfunction in the elderly - what are the differences?

Background Postoperative delirium (PD) is a serious complication after major surgery in elderly patients. PD is well defined and characterized by reduced attention and disorientation. Multimodal optimization of perioperative care (the fast-track methodology) enhances recovery, and reduces hospital stay and medical morbidity. No data on PD are available in fast-track surgery. The aim of this study was to evaluate the incidence of PD after fast-track hip (THA) and knee arthroplasty (TKA) with anticipated length of stay (LOS) of Methods In a prospective multicentre study to evaluate postoperative cognitive dysfunction, we included 225 non-demented patients with a mean age of 70 yr undergoing either THA or TKA in a fast-track set-up. Anaesthesia and postoperative pain management were standardized with limited opioid use. Nursing staff were trained to look for symptoms of PD which was assessed during interaction with healthcare professionals. Patients were invited for a clinical follow-up 1–2 weeks after surgery. Results Clinical follow-up was performed in 220 patients at a mean of 12.0 days after surgery while five patients were followed up by telephone. The mean LOS was 2.6 days (range 1–8 days). Twenty-two patients received general anaesthesia, and the rest had spinal anaesthesia. No patients developed PD (95% confidence interval 0.0–1.6%). Conclusions A fast-track set-up with multimodal opioid-sparing analgesia was associated with lack of PD after elective THA and TKA in elderly patients.

Lene Krenk

Papers

New insights into the pathophysiology of postoperative cognitive dysfunction

A high and increasing HPV prevalence in tonsillar cancers in Eastern Denmark, 2000-2010: the largest registry-based study to date.

Cognitive dysfunction after fast-track hip and knee replacement.

Postoperative delirium and postoperative cognitive dysfunction in the elderly - what are the differences?

Delirium after fast-track hip and knee arthroplasty