Background: Pain that lingers beyond the early weeks after the acute postoperative period is an important risk factor for chronic postsurgical pain. This study examined the hypothesis that patients' expectations about their postsurgical pain would be independently associated with lingering postsurgical pain. Methods: The study included 3,628 patients who underwent diverse surgeries between February 2015 and October 2016 in a single U.S. tertiary hospital and participated in the Systematic Assessment and Targeted Improvement of Services Following Yearlong Surgical Outcomes Surveys (SATISFY-SOS) observational study. Preoperatively, patients were asked about their expectations about pain 1 month after surgery. Patients were considered to have lingering postsurgical pain if they endorsed having pain in the area related to their surgeries during a follow-up survey obtained 1 to 3 months postoperatively. The independent associations between preselected perioperative variables and lingering postsurgical pain were evaluated. Results: Of the cohort, 36% (1,308 of 3,628) experienced lingering postsurgical pain. Overall, two thirds (2,414 of 3,628) expected their postsurgical pain to be absent or improved from baseline, and 73% of these had their positive expectations fulfilled. A total of 19% (686 of 3,628) expected new, unabated, or worsened pain, and only 39% (257 of 661) of these had their negative expectations fulfilled. Negative expectations were most common in patients with presurgical pain unrelated to the reason for surgery, undergoing surgeries not typically performed to help alleviate pain. Endorsing negative expectations was independently associated with lingering postsurgical pain (odds ratio, 1.56; 95% CI, 1.23 to 1.98; P < 0.001). Additional major factors associated with lingering postsurgical pain included recollection of severe acute postoperative pain (odds ratio, 3.13; 95% CI, 2.58 to 3.78; P < 0.001), undergoing a procedure typically performed to help alleviate pain (odds ratio, 2.18; 95% CI, 1.73 to 2.75; P < 0.001), and preoperative pain related to surgery (odds ratio, 1.91; 95% CI, 1.52 to 2.40; P < 0.001). Conclusions: Lingering postsurgical pain is relatively common after diverse surgeries and is associated with both fixed surgical characteristics and potentially modifiable factors like pain expectations and severe acute postoperative pain.

Examples of comorbidities for the widely used American Society of Anesthesiologists physical status (ASA-PS) classification system were developed and approved in 2014. We conducted a retrospective cohort study of patients with 4 comorbidities included in the examples as warranting a specific minimum ASA-PS class. For each comorbidity subgroup, we used interrupted time-series models to compare ASA-PS underclassification for the periods before (2011-2014) and after (2015-2017) the introduction of examples. Rates of underclassification ranged from 4.8% to 38.7%. We observed no evidence of a significant impact on ASA-PS classification with the introduction of examples in 2014.

BACKGROUND: A new billable code for intraoperative cardiac arrest was introduced with the International Classification of Diseases, Tenth Revision, classification system. Using a national administrative database, we performed a retrospective analysis of intraoperative cardiac arrest in the United States. METHODS: Hospital admissions involving patients ≥18 years of age who underwent operating room procedures in 2016 were identified using the National Inpatient Sample. The primary outcome was the incidence of intraoperative cardiac arrest. Secondary outcomes included total cost of admission, in-hospital mortality, length of stay, and identification of risk factors associated with intraoperative cardiac arrest. Clinical risk factors were evaluated with multivariable logistic regression models using sampling weights and adjustment for clustering by strata. RESULTS: Of 35,675,421 admissions in 2016 in the United States, 9,244,861 admissions were identified in patients ≥18 years of age who underwent at least one operating room procedure. An estimated 5230 hospital admissions involved intraoperative cardiac arrest, yielding an estimated incidence of 5.7 (95% confidence interval [CI], 5.3–6.0) per 10,000 hospital admissions. Admissions involving an intraoperative cardiac arrest had a 35.7% in-hospital mortality, compared with 1.3% for admissions without intraoperative cardiac arrest. Intraoperative cardiac arrest was associated with a 15.44-fold (95% CI, 12.74–18.70; P < .001) increase in the risk-adjusted odds of in-hospital mortality and an additional $13,184 (95% CI, 9600–16,769; P < .001) of total admission costs. Selected factors independently associated with increased risk-adjusted odds of intraoperative cardiac arrest included: black or missing race; cardiac, thoracic, or vascular surgery; congestive heart failure; pulmonary circulation disorders; peripheral vascular disease; end-stage renal disease; and fluid and electrolyte disorders. CONCLUSIONS: In this population-based study of intraoperative cardiac arrest in the United States, admissions involving an intraoperative cardiac arrest were rare but were associated with high in-hospital mortality.

OBJECTIVE:To determine if diastolic dysfunction is independently associated with increased mortality, acute kidney injury, and hospital length of stay after noncardiac surgery.DESIGN:Retrospective observational cohort.SETTING:Academic referral center.PARTICIPANTS:All patients undergoing noncardiac and nonliver-transplant surgeries at University of California - Los Angeles between April 2013 and October 2017, who also had transthoracic echocardiograms performed within 6 months preceding their procedures.INTERVENTIONS:None.MEASUREMENTS AND MAIN RESULTS:Patients' demographic, comorbidity, echocardiographic, and perioperative data were queried from the electronic health record. Diastolic dysfunction was graded by automated application of 2016 American Society of Echocardiography guidelines to queried echocardiographic measurements. During the study period, 12,871 eligible records were identified, of which 7,312 represented unique procedures with complete information. Twenty-three percent of patients had echocardiographic evidence of diastolic dysfunction (7.0% grade 1, 8.1% grade 2, 0.6% grade 3, and 7.5% nonspecific). Patients with diastolic dysfunction tended to be older and have higher American Society of Anesthesiologists scores with more comorbidities. Overall, 166 patients (2.3%) experienced an in-hospital death. After adjustment for potentially confounding variables, diastolic dysfunction was not significantly associated with increased in-hospital mortality, acute kidney injury, or hospital length of stay.CONCLUSIONS:Diastolic dysfunction does not appear to be associated with increased in-hospital mortality, acute kidney injury, or hospital length of stay in a cohort of noncardiac surgical patients at an academic medical center. These results highlight uncertainties in perioperative risk determination.

BACKGROUND:Post-surgical pain that lingers beyond the initial few-week period of tissue healing is a major predictor of pain chronification, which leads to substantial disability and new persistent opioid analgesic use. We investigated whether postoperative medical complications increase the risk of lingering post-surgical pain.METHODS:The study population consisted of patients undergoing diverse elective surgical procedures in an academic referral centre in the USA, between September 2013 and May 2017. Multivariable logistic regression, adjusting for confounding variables and patient-specific risk factors, was used to test for an independent association between any major postoperative complication and functionally limiting lingering pain 1-3 months after surgery, as obtained from patient self-reports.RESULTS:The cohort included 11 986 adult surgical patients; 10 562 with complete data. At least one complication (cardiovascular, respiratory, renal/gastrointestinal, wound, thrombotic, or neural) was reported by 13.3% (95% confidence interval: 12.7-14.0) of patients, and 19.7% (19.0-20.5%) reported functionally limiting lingering post-surgical pain. After adjusting for known risk factors, the patients were twice as likely (odds ratio: 2.04; 1.78-2.35) to report lingering post-surgical pain if they also self-reported a postoperative complication. Experiencing a complication was also independently predictive of lingering post-surgical pain (odds ratio: 1.95; 1.26-3.04) when complication data were extracted from the National Surgical Quality Improvement Program registry, instead of being obtained from patient self-report.CONCLUSIONS:Medical complications were associated with a two-fold increase in functionally limiting pain 1-3 months after surgery. Understanding the mechanisms that link complications to pathological persistence of pain could help develop future approaches to prevent persistent post-surgical pain.

OBJECTIVES/SPECIFIC AIMS: To study the role of OSA as an independent predictor of perioperative outcomes. METHODS/STUDY POPULATION: For this single-institution cohort study, we included data from patients who were enrolled into 1 of 3 prospective parent studies. All participants underwent in-patient surgeries, excluding neurosurgeries, which required general anesthesia and a postoperative stay of at least 1 day. Patients included in this study were assessed daily for postoperative delirium and pain severity as part of the parent studies. In the current study, determination of delirium diagnosis was based on the 3-minute Diagnostic Confusion Assessment Method (3D-CAM), and the Visual Analogue Pain Scale (VAS) was used for pain severity. Data on OSA diagnosis (determined by sleep study); OSA risk (determined by the STOP-Bang tool; snoring, tiredness, observed apnea, high blood pressure, body mass index>35 kg/m2, age>50, neck circumference, male gender); and compliance with treatment were obtained from the preoperative assessment record. Participants were grouped into 1 of 3 categories: high risk of OSA (HR-OSA; including patients with a previous positive sleep study or STOP-Bang score ≥5); intermediate risk of OSA (IR-OSA; including patients with a STOP-Bang score of 3 or 4); and low risk of OSA (LR-OSA; including patients with a previous negative sleep study or STOP-Bang score <3). Candidate risk factors for delirium and pain were also extracted from this record. RESULTS/ANTICIPATED RESULTS: Logistic regression will be used to test whether OSA independently predicts postoperative delirium and linear regression to assess OSAs relationship to acute pain severity. We hypothesize that patients in the HR-OSA category will experience a higher incidence of postoperative delirium and greater postoperative pain severity. We also predict a step-wise increase in risk of these adverse outcomes when analyzing patients stratified by OSA risk (HR-OSA vs. IR-OSA vs. LR-OSA). For our secondary analyses, we anticipate these outcomes are modified by compliance with CPAP treatment. We believe patients with OSA who do not use prescribed CPAP will experience a higher incidence of postoperative delirium as well as increased pain severity. DISCUSSION/SIGNIFICANCE OF IMPACT: OSA is a common and frequently undiagnosed perioperative problem associated with altered pain processing and a high incidence of postoperative delirium. While likely providing stronger evidence of OSA’s reported impact on postoperative delirium and pain, our findings might also help discern points of intervention for treatment and prevention. Since OSA’s presumed impact poses challenges to clinicians and patients, prospective, randomized trials testing preventative or mitigating interventions are necessary. We hope to use these results to design such trials and clinical plans, with the goal of reducing postoperative delirium and acute postsurgical pain severity for the large number of patients at risk due to OSA.

Since the report by Monk and colleagues1 of an association between a cumulative duration of the bispectral index (BIS) <45 and postoperative mortality there has been debate regarding the plausibility that relatively excessive anaesthetic depth is deadly. It is not surprising that this premise has ignited a scientific controversy and that anaesthetists are both intellectually and emotionally vested in its resolution. If this hypothesis were indeed true, the concentration of (volatile) anaesthetic promoting death would be within what is currently considered the therapeutic window.

BACKGROUND:Patient memories of the operating room (OR) may serve as the informational basis for assessing satisfaction with individual anesthesiologists. Furthermore, the provision of clinically important information may assume that perioperative memories are retained. Studies assessing the extent of perioperative amnesia and factors associated with perioperative amnesia are sparse. Therefore, we assessed patient amnesia of the OR and of the preoperative holding area in hospitals where midazolam is typically administered in the preoperative holding area and evaluated whether midazolam dose administered in the preoperative holding area and patient age were associated with amnesia of the OR before induction of anesthesia. METHODS:This was a retrospective study among 7750 adult patients who had general anesthesia and participated in the B-Unaware and Bispectral Index or Anesthetic Gas to Reduce Explicit Recall (BAG-RECALL) clinical trials. The last location the patient remembered before induction of anesthesia and the first location they remembered after induction of anesthesia were determined through a modified Brice questionnaire administered over the phone 30 days postoperatively. Regarding the preoperative period, patients were excluded if their last memory was unclear with respect to location before induction of anesthesia or if they were recruited at Winnipeg, where midazolam was typically first administered in the OR. Midazolam dose (mg/kg) administered in the preoperative holding area was divided into quartiles. Poisson regression models were used to calculate age- and multivariable-adjusted odds ratios (95% confidence intervals [CIs]) for the association between midazolam dose and amnesia of the OR before induction of anesthesia. RESULTS:Of the 5339 patients included, 59.5% (95% CI, 58.2–60.9) of patients had amnesia of the OR before induction of anesthesia. In addition, 44.1% (95% CI, 42.8–45.7) last remembered the preoperative holding area, and 15.4% (95% CI, 14.4–16.4) only had preoperative memories before the holding area. The percentages of patients with amnesia of the OR before induction of anesthesia differed according to age groups: 50.7% (95% CI, 47.7%–53.7%) in patients aged 18 to 47 years versus 70.0% (95% CI, 67.0%–72.9%) in patients aged 73 to 99 years. Patients in the highest midazolam quartile had an adjusted prevalence ratio of 1.31 (95% CI, 1.22–1.42) for amnesia of the OR compared with those who did not receive midazolam. CONCLUSIONS:In hospitals where patients typically receive midazolam in the preoperative holding area, the majority of patients do not remember the OR, and a clinically relevant number of patients does not remember the preoperative holding area. If additional studies produce results indicating that a substantial proportion of patients has amnesia of the anesthesiologist, these findings would argue against the validity of assessing patient satisfaction with individual anesthesiologists providing exclusively OR care in such hospitals. Furthermore, if additional studies yield findings suggesting patient amnesia of the preoperative holding area, these results would suggest reconsideration of providing clinically important information only in the preoperative holding area. Older age and midazolam-induced anterograde amnesia are probably associated with impaired perioperative memories.

Background: An intraoperative concurrence of mean arterial pressure less than 75 mmHg, minimum alveolar concentration less than 0.8, and bispectral index less than 45 has been termed a “triple low” state. An association between triple low and postoperative mortality has been reported but was not replicated in a subsequent study. The authors pooled existing data from clinical trials to further evaluate the purported association in an observational study. Methods: This retrospective observational study included 13,198 patients from three clinical trials: B-Unaware, BAG-RECALL, and Michigan Awareness Control Study. Patients with greater than 15 not necessarily consecutive minutes of triple low were propensity matched to controls with similar characteristics and comorbidities. A multivariable Cox proportional hazards model was used to evaluate the association between triple low duration and postoperative mortality. Results: Thirty-day mortality was 0.8% overall, 1.9% in the triple low cohort, and 0.4% in the nontriple low cohort (odds ratio, 5.16; 95% CI, 4.21 to 6.34). After matching and adjusting for comorbidities, cumulative duration of triple low was significantly associated with an increased risk of mortality at 30 days (hazard ratio, 1.09; 95% CI, 1.07 to 1.11, per 15 min) and 90 days (hazard ratio, 1.09; 95% CI, 1.08 to 1.11, per 15 min). Conclusion: There is a weak independent association between the triple low state and postoperative mortality, and the propensity-matched analysis does not suggest that this is an epiphenomenon.

Anatomical, neurological and behavioural research has suggested differences between the brains of right- and non-right-handed individuals, including differences in brain structure, electroencephalogram patterns, explicit memory and sleep architecture. Some studies have also found decreased longevity in left-handed individuals. We therefore aimed to determine whether handedness independently affects the relationship between volatile anaesthetic concentration and the bispectral index, the incidence of definite or possible intra-operative awareness with explicit recall, or postoperative mortality. We studied 5585 patients in this secondary analysis of data collected in a multicentre clinical trial. There were 4992 (89.4%) right-handed and 593 (10.6%) non-right-handed patients. Handedness was not associated with (a) an alteration in anaesthetic sensitivity in terms of the relationship between the bispectral index and volatile anaesthetic concentration (estimated effect on the regression relationship -0.52 parallel shift; 95% CI -1.27 to 0.23, p = 0.17); (b) the incidence of intra-operative awareness with 26/4992 (0.52%) right-handed vs 1/593 (0.17%) non-right-handed (difference = 0.35%; 95% CI -0.45 to 0.63%; p = 0.35); or (c) postoperative mortality rates (90-day relative risk for non-right-handedness 1.19, 95% CI 0.76-1.86; p = 0.45). Thus, no change in anaesthetic management is indicated for non-right-handed patients.

BACKGROUND Low bispectral index values frequently reflect EEG suppression and have been associated with postoperative mortality. This study investigated whether intraoperative EEG suppression was an independent predictor of 90 day postoperative mortality and explored risk factors for EEG suppression. METHODS This observational study included 2662 adults enrolled in the B-Unaware or BAG-RECALL trials. A cohort was defined with >5 cumulative minutes of EEG suppression, and 1:2 propensity-matched to a non-suppressed cohort (≤5 min suppression). We evaluated the association between EEG suppression and mortality using multivariable logistic regression, and examined risk factors for EEG suppression using zero-inflated mixed effects analysis. RESULTS Ninety day postoperative mortality was 3.9% overall, 6.3% in the suppressed cohort, and 3.0% in the non-suppressed cohort {odds ratio (OR) [95% confidence interval (CI)]=2.19 (1.48-3.26)}. After matching and multivariable adjustment, EEG suppression was not associated with mortality [OR (95% CI)=0.83 (0.55-1.25)]; however, the interaction between EEG suppression and mean arterial pressure (MAP) <55 mm Hg was [OR (95% CI)=2.96 (1.34-6.52)]. Risk factors for EEG suppression were older age, number of comorbidities, chronic obstructive pulmonary disease, and higher intraoperative doses of benzodiazepines, opioids, or volatile anaesthetics. EEG suppression was less likely in patients with cancer, preoperative alcohol, opioid or benzodiazepine consumption, and intraoperative nitrous oxide exposure. CONCLUSIONS Although EEG suppression was associated with increasing anaesthetic administration and comorbidities, the hypothesis that intraoperative EEG suppression is a predictor of postoperative mortality was only supported if it was coincident with low MAP. CLINICAL TRIAL REGISTRATION NCT00281489 and NCT00682825.

Copyright © 2013 International Anesthesia Research Society It is hypothesized that incorporating a brain monitor, like the Bispectral Index (BIS), into routine anesthetic practice can improve anesthetic management and patient outcomes by eschewing both too little and unnecessarily deep anesthesia. By avoiding light anesthesia, intraoperative awareness and its attendant complications, like posttraumatic stress disorder, can be prevented. Evidence from several large trials suggests that a BIS-based protocol decreases intraoperative awareness with postoperative recall when total IV anesthesia with pharmacological paralysis is administered.1–3 However, when anesthesia is based on a potent volatile drug, a BIS-based protocol is not superior to a protocol based on exhaled anesthetic concentration in preventing awareness with recall (Figure 1).3–6 Unnecessarily deep anesthesia is almost certainly associated with prolonged recovery and poorer quality of recovery. More controversially, deep anesthesia has been postulated to increase directly a variety of postoperative complications, including mortality, delirium, cognitive decline, dementia, myocardial infarction, stroke, renal failure and cancer. Some trials have indicated that a BIS-based protocol may decrease anesthetic administration and improve early recovery (discharge from postanesthesia care unit, nausea, vomiting) compared with routine care or an alternative protocol,7,8 but other trials have not replicated these findings.1,3,9 An association has been noted between the cumulative duration of low BIS and intermediate-term mortality (1–4 years);10–12 this association was independent of anesthesia duration or volatile anesthetic concentration. Other studies have not found that cumulative duration of BIS<45 in isolation was connected with increased mortality.13,14 A concurrence of low BIS, low anesthetic concentration and low arterial blood pressure, the “triple low” phenomenon, has been linked to increased all-cause postoperative mortality.14 The clinical relevance of this finding is currently uncertain, and might simply reflect patient vulnerability.15 If the link between triple low and death is causal, the pathophysiologic mechanisms by which triple low could indiscriminately increase mortality, especially cancer deaths, are unclear.15 Thus, relations between intraoperative BIS values (or other surrogate measures of anesthetic depth) and adverse postoperative outcomes (e.g., death, myocardial infarction, stroke, renal failure, cognitive decline, dementia, cancer recurrence) require scrupulous investigation. There is mounting evidence from several randomized, controlled trials that a BIS-based protocol can decrease postoperative delirium, possibly by decreasing anesthetic administration or by minimizing epochs of electroencephalographic burst suppression.8,16,17 The results of an unpublished meta-analysis [Whitlock et al.] of four randomized studies comparing BIS-guided anesthesia with a control group (routine care or an alternative protocol) suggest that BIS-guided anesthesia lessens postoperative delirium, with a summary odds ratio of 0.56 (95% confidence interval, 0.42 to 0.73) (Figure 2).8,16–18 Although the finding is compelling, the mechanism for decreased delirium is unclear because most large studies have not demonstrated that BIS guidance alters average anesthetic administration.3–5,16 Furthermore, logic would suggest that if a slight reduction in general anesthetic administration is associated with improved clinical outcomes, the use of no general anesthesia (e.g., medical management or regional anesthesia) should result in substantially better outcomes. On the contrary, meta-analyses of trials that have randomized patients to general or regional anesthesia for surgical procedures and large effectiveness trials that have randomized patients to major surgery with deep general anesthesia versus nonsurgical management (e.g., coronary artery bypass grafting versus percutaneous stenting) have failed to demonstrate an improvement in outcomes (e.g., mortality, cognitive decline, delirium, quality of life) up to five years later with regional anesthesia or nonsurgical, nonanesthetic management.19–24 Before we can conclude that a minor decrement in anesthetic concentration (or anesthetic depth) improves outcomes, we must demonstrate that general anesthesia at any concentration is injurious to patients. Although skepticism is important and we should not reach overly hasty inferences, there is accumulating evidence that brain monitoring helps practitioners to administer anesthesia more appropriately for some individual patients, and is therefore likely to be associated with some improvements in patient outcomes. Hence brain monitoring during general anesthesia could enjoy more widespread adoption. In the United Kingdom, for example, guidelines from the National Institute for Health and Care Excellence (NICE) recommend the use of electroencephalography-based brain monitoring, especially in vulnerable patients.25 Implementation of these guidelines has been controversial due to the lack of definitive evidence for the benefit of such monitors26 and insufficient information on what constitutes “vulnerability.” Thus, most anesthesiologists in the United Kingdome currently do not follow the NICE guidelines, and either through choice or unavailability of the devices, do not use electroencephalographybased brain monitors.27 Nonetheless, brain monitoring is heuristically appealing as the brain is the target organ of general anesthesia. The BIS is only one of many available brain monitors; while it has been an important advance and has helped focus the attention of the anesthesiology Bispectral Index Monitoring and Perioperative Outcomes: Does It Make a Difference?

Objective: A recent investigation at Barnes-Jewish Hospital located in St. Louis, Missouri, found that an estimated 22% of adults presenting for inpatient surgery screened as high risk for obstructive sleep apnea (OSA). Surgical patients with OSA have multiple comorbidities and are at increased risk for perioperative complications. Our objective was to determine if a prior diagnosis of OSA or a positive screen for OSA was associated with increased risk for 30-day and one-year mortality.Methods: B-J APNEAS (Barnes-Jewish Apnea Prevalence in Every Admission Study) was a prospective cohort study. Unselected adult surgical patients at Barnes Jewish Hospital were prospectively enrolled between February 2006 and April 2010. All patients completed preoperative OSA screening and those who were at risk for OSA according to a combination of the Berlin and Flemons screening tools received targeted postoperative interventions. STOP (loud Snoring, daytime Tiredness, Observed apneas, and high blood Pressure) and STOP-BANG (STOP, plus body mass index [BMI], age, neck circumference, and gender) scores also were obtained.Results: Overall, the sample included 14,962 patients, of whom 1939 (12.9%) reported a history of OSA. All four screening tools identified a high prevalence of undiagnosed patients at risk for OSA (9.5%-41.6%), but agreement among screens was not strong with kappa statistic ranging from 0.225 to 0.611. There was no significant difference in 30-day postoperative mortality between patients with possible OSA (based on their history or on a positive OSA screen with any of the four instruments) and the rest of the surgical population. Significant differences in one-year mortality were noted between the low-risk and high-risk groups as identified by the Flemons' (4.96% vs 6.91%; p < 0.0001), STOP (5.28% vs 7.57%; p < 0.0001) and STOP-BANG (4.13% vs 7.45%; p < 0.0001) screens. After adjusting for risk factors, none of the OSA screening tools independently predicted mortality rate up to one year postoperatively.Conclusion: Neither a prior diagnosis of OSA nor a positive screen for OSA risk was associated with increased 30-day or one-year postoperative mortality. Differences in 1 year postoperative mortality were noted with three of the screening tools. The results of our study highlight uncertainties and research priorities for the medical community. (c) 2012 Elsevier B.V. All rights reserved.

© 2013 International Anesthesia Research Society. Unauthorized Use Prohibited attention of the anesthesiology community on the brain, BIS has important limitations that must be addressed in future devices. 26, 28-31 New brain monitoring approaches rooted in principles of neurobiology are being explored and could make the administration of general anesthesia less based on gestalt and median population parameters, and more driven by measured effects on its target organ. 32-35

Electroencephalography (EEG) offers utility as a surrogate monitor of anesthetic depth, potentially facilitating a "Goldilocks" anesthetic plan of "just right" patient centered dosing. Despite the proposed benefits, clinical incorporation has been slow, and there have been many conflicting results regarding the ability of EEG monitoring to improve clinical outcomes. This review summarizes features of EEG waveforms during wakefulness, sedation and general anesthesia. The literature regarding the effectiveness of processed EEG monitoring in preventing intraoperative awareness with recall is critically summarized; the strongest evidence for processed EEG monitoring is in the setting of total intravenous anesthesia. Preliminary evidence regarding the utility of processed EEG monitoring in preventing unnecessarily deep anesthesia and its hypothesized adverse effects is discussed. A provocative association has been noted between certain EEG features, such as burst suppression, and adverse early and intermediate term outcomes, such as delirium and death. However, whether such associations are causal or epiphenomenal is currently unknown. Finally, the limitations of current EEG monitors and the features of an ideal EEG monitor are described. (C) 2012 Elsevier Ltd. All rights reserved.

Mice may be useful for studies of skeletal aging, but there are limited data on changes in bone structure and strength over their life span. We obtained bones from female and male BALB/c mice at ages 2, 4, 7, 12, and 20 months and evaluated their structural, densitometric, and mechanical properties. MicroCT of the mid-diaphysis of the femur and radius indicated that during skeletal growth (2-7 months) bone cross-sectional size (area, moment of inertia) increased rapidly; during aging (7-20 months) cortical area was maintained, while moment of inertia continued to increase. Bones from females were smaller than those from males at young ages but not at later ages. Changes in whole-bone stiffness and strength reflected the changes in bone size, with a rapid increase from 2 to 7 months, followed by little or no change. In contrast, energy-to-fracture declined with aging. Cortical tissue mineral density increased during growth and was maintained with aging. MicroCT of trabecular bone revealed age-related changes that were site-dependent. The proximal tibia showed a clear pattern of age-related decline in trabecular BV/TV, with progressive decreases after 4 months in both sexes; lumbar vertebra L5 had more modest age-related declines; in contrast, caudal vertebra Ca7 had increasing BV/TV with aging. Overall, we found no evidence that females had more pronounced age-related deterioration than males. We conclude that bones from aging female and male BALB/c mice exhibit many of the changes seen in humans and are therefore a clinically relevant model for studies of skeletal aging.