bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-term Consequences of Postoperative Cognitive Dysfunction
Authors: Steinmetz Jacob , Christensen Karl Bang , Lund Thomas , Lohse Nicolai , Rasmussen Lars S. 
Published: February 2009

Background
Postoperative cognitive dysfunction (POCD) is common in elderly patients after noncardiac surgery, but the consequences are unknown. The authors' aim was to determine the effects of POCD on long-term prognosis.

Methods
This was an observational study of Danish patients enrolled in two multicenter studies of POCD between November 1994 and October 2000. The cohort was followed up from the date of surgery until August 2007. Cognitive function was assessed by a neuropsychological test battery at three time points: before, at 1 week after, and at 3 months after noncardiac surgery. Data on survival, labor market attachment, and social transfer payments were obtained from administrative databases. The Cox proportional hazards regression model was used to compute relative risk estimates for mortality and disability, and the relative prevalence of time on social transfer payments was assessed by Poisson regression.

Results
A total of 701 patients were followed up for a median of 8.5 yr (interquartile range, 5.3-11.4 yr). POCD at 3 months, but not at 1 week, was associated with increased mortality (hazard ratio, 1.63 [95% confidence interval, 1.11-2.38]; P = 0.01, adjusted for sex, age, and cancer). The risk of leaving the labor market prematurely because of disability or voluntary early retirement was higher among patients with 1-week POCD (hazard ratio, 2.26 [1.24-4.12]; P = 0.01). Patients with POCD at 1 week received social transfer payments for a longer proportion of observation time (prevalence ratio, 1.45 [1.03-2.04]; P = 0.03).

Conclusions
Cognitive dysfunction after noncardiac surgery was associated with increased mortality, risk of leaving the labor market prematurely, and dependency on social transfer payments.
Role for Metallothioneins-I/II in Isoflurane Preconditioning of Primary Murine Neuronal Cultures
Authors: Edmands Scott D. , Hall Adam C. 
Published: February 2009

Background
Pretreatment with inhaled anesthetics, including isoflurane, can induce long-lasting cellular protection against ischemia-derived toxicity in multiple tissues, including brain tissue. Metal-regulatory genes, metallothioneins-I/II (MT-I/II), have been shown to protect against oxidative damage in multiple tissues. Furthermore, MT have been found to be differentially regulated in response to isoflurane and ischemic preconditioning. In this study, we assess the role of MT-I/II in mediating isoflurane preconditioning in primary neuronal-glial cultures.

Methods
Primary mouse neuronal-glial cultures were preconditioned with isoflurane (3 h, 1.5%) 24-96 h before 3-h oxygen-glucose deprivation (OGD, ischemic model). After OGD, isoflurane protection and responsiveness of MT-I/II knockdown and knockout cultures to preconditioning were assessed by lactate dehydrogenase release. Immunoassays for microtubule associated protein 2 and glial fibrillary acidic protein determined neuronal-glial sensitivity to preconditioning. MT-I/II messenger RNA was assessed by quantitative reverse transcriptase-polymerase chain reaction. Cultures transfected with exogenous MT-I/II were analyzed for protection against OGD toxicity.

Results
Isoflurane preconditioning reduced OGD-mediated toxicity by 11.6 +/- 7.9% at 24 h, with protection increasing to 37.5 +/- 2.5% at 72 h after preconditioning. Immunolabeling showed that neurons were more sensitive to OGD and more responsive to isoflurane preconditioning compared to glia. Quantitative reverse transcriptase-polymerase chain reaction showed MT-I/II messenger RNA were upregulated (approximately 2.5-fold) by isoflurane treatments. Also MT-I/II protein transfection significantly decreased OGD-mediated toxicity. Finally, knockdown and knockout of MT-I/II diminished and abolished isoflurane-mediated protection, respectively.

Conclusions
MT-I/II play an important role in isoflurane-mediated delayed preconditioning against OGD toxicity of neuronal and glial cells in vitro.
Intraoperative Fraction of Inspired Oxygen Is a Modifiable Risk Factor for Surgical Site Infection after Spinal Surgery
Authors: Maragakis Lisa L. , Cosgrove Sara E. , Martinez Elizabeth A. , Tucker Margaret G. , Cohen David B. , Perl Trish M. 
Published: February 2009

Background
Surgical site infections (SSI) after spinal surgery increase morbidity, mortality, length of hospital stay, and costs. Most previously identified risk factors for these infections, such as severity of illness and procedure duration, are not amenable to intervention. This study sought to identify modifiable risk factors associated with SSI after spinal surgery.

Methods
This is a case-control study including case identification and review of medical records. A total of 104 patients with SSI after spinal surgery were compared to 104 randomly selected control patients without SSI after spinal surgery in a 926-bed tertiary care hospital in Baltimore, Maryland, between April 1, 2001 and December 31, 2004.

Results
Multivariate analysis identified independent risk factors for SSI after spinal surgery including prolonged procedure duration (odds ratio [OR], 4.7; 95% confidence interval [95% CI], 1.6-14; P < 0.001), American Society of Anesthesiologists score of 3 or greater (OR, 9.7; 95% CI, 3.7-25; P < 0.001), lumbar-sacral operative level (OR, 2.9; 95% CI, 1.2-7.1; P = 0.02), posterior approach (OR, 3.5; 95% CI, 1.2-9.7; P = 0.02), instrumentation (OR, 2.5; 95% CI, 1.1-6.0; P = 0.03), obesity (OR, 4.0; 94% CI, 1.6-10; P < 0.01), razor shaving before surgery (OR, 3.6; 95% CI, 1.2-11; P = 0.02), and intraoperative administered fraction of inspired oxygen of less than 50% (OR, 12; 94% CI, 4.5-33; P < 0.001).

Conclusions
In addition to previously reported risk factors, this study identified intraoperative administered fraction of inspired oxygen of less than 50% as an independent, modifiable risk factor for SSI after spinal surgery. Intraoperative administration of at least 50% fraction of inspired oxygen should be tested prospectively as an intervention to prevent SSI after spinal surgery.
Further Proof that the Spinal Cord, and Not the Brain, Mediates the Immobility Produced by Inhaled Anesthetics
Authors: Yang Jing , Chai Yun-Fei , Gong Chun-Yu , Li Guo-hua , Luo Nan , Luo Nan-Fu , Liu Jin 
Published: February 2009

Background
Previous investigations indicate that the spinal cord, perhaps with a minor cerebral contribution, mediates the capacity of inhaled anesthetics to produce immobility in the face of noxious stimulation. The implications of these investigations may be limited by the trauma associated with their experimental methods (e.g., cardiopulmonary bypass or transection of the spinal cord). The present study avoided such trauma.

Methods
Thirty goats received emulsified isoflurane via either the initial section of the aorta (arterial group; preferential isoflurane delivery to the spinal cord) or an ear vein (venous group; equal delivery of isoflurane to the cord and brain). The authors determined the minimum partial pressure of isoflurane (the isoflurane partial pressure in the blood required to produce immobility in 50% of the goats exposed to a noxious stimulus).

Results
For the venous group, the minimum partial pressure in carotid versus femoral arterial blood (9.56 +/- 1.86 mmHg vs. 9.68 +/- 1.90 mmHg) did not differ. For the arterial group, the minimum partial pressure in carotid arterial blood was half that in femoral arterial blood (5.35 +/- 1.45 mmHg vs. 10.97 +/- 3.04 mmHg, P < 0.05). As these data show, the minimum partial pressure in femoral arterial blood did not differ for the arterial group versus the venous group.

Conclusions
In this novel and minimally traumatic model, the anesthetic partial pressure delivered to the spinal cord governed the suppression of movement in response to noxious stimulation. The results indicate that the spinal cord is the primary mediator of immobility and that the brain plays little or no role.
Isoflurane Suppresses Stress-enhanced Fear Learning in a Rodent Model of Post–Traumatic Stress Disorder
Authors: Rau Vinuta , Oh Irene , Laster Michael , Eger Edmond I. , Fanselow Michael S. 
Published: February 2009

Background
A minority of patients who experience awareness and/or pain during surgery subsequently develop post-traumatic stress disorder. In a rodent model of post-traumatic stress disorder, stress-enhanced fear learning (SEFL), rats are preexposed to a stressor of 15 foot shocks. Subsequent exposure to a single foot shock produces an enhanced fear response. This effect is akin to sensitized reactions shown by some post-traumatic stress disorder patients to cues previously associated with the traumatic event.

Methods
The authors studied the effect of isoflurane and nitrous oxide on SEFL. Rats were exposed to the inhaled anesthetic during or after a 15-foot shock stressor. Then, rats were given a single foot shock in a different environment. Their fear response was quantified in response to the 15-foot shock and single-foot shock environments. SEFL longevity was tested by placing a 90-day period between the 15 foot shocks and the single foot shock. In addition, the intensity of the foot shock was increased to evaluate treatment effectiveness.

Results
Increasing isoflurane concentrations decreased SEFL when given during, but not after, the stressor. At 0.40 minimum alveolar concentration (MAC), isoflurane given during the stressor blocked SEFL 90 days later. A threefold increase in the stressor intensity increased the isoflurane concentration required to block SEFL to no more than 0.67 MAC. As with isoflurane, nitrous oxide suppressed SEFL at a similar MAC fraction.

Conclusions
These results suggest that sufficient concentrations (perhaps 0.67 MAC or less) of an inhaled anesthetic may prevent SEFL.
Neonatal Exposure to Sevoflurane Induces Abnormal Social Behaviors and Deficits in Fear Conditioning in Mice
Authors: Satomoto Maiko , Satoh Yasushi , Terui Katsuo , Miyao Hideki , Takishima Kunio , Ito Masataka , Imaki Junko 
Published: February 2009

Background
Neonatal exposure to anesthetics that block N-methyl-D-aspartate receptors and/or hyperactivate gamma-aminobutyric acid type A receptor has been shown to cause neuronal degeneration in the developing brain, leading to functional deficits later in adulthood. The authors investigated whether exposure of neonatal mice to inhaled sevoflurane causes deficits in social behavior as well as learning disabilities.

Methods
Six-day-old C57BL/6 mice were exposed to 3% sevoflurane for 6 h. Activated cleaved caspase-3 immunohistochemical staining was used for detection of apoptosis. Cognitive functions were tested by pavlovian conditioned fear test. Social behavior was tested by social recognition and interaction tests.

Results
Neonatal exposure to sevoflurane significantly increased the number of apoptotic cells in the brain immediately after anesthesia. It caused persistent learning deficits later in adulthood as evidenced by decreased freezing response in both contextual and cued fear conditioning. The social recognition test demonstrated that mice with neonatal exposure to sevoflurane did not develop social memory. Furthermore, these mice showed decreased interactions with a social target compared with controls in the social interaction test, indicating a social interaction deficit. The authors did not attribute these abnormalities in social behavior to impairments of general interest in novelty or olfactory sensation, because they did not detect significant differences in the test for novel inanimate object interaction or for olfaction.

Conclusions
This study shows that exposure of neonatal mice to inhaled sevoflurane could cause not only learning deficits but also abnormal social behaviors resembling autism spectrum disorder.
Adaptive Support and Pressure Support Ventilation Behavior in Response to Increased Ventilatory Demand
Authors: Jaber Samir , Sebbane Mustapha , Verzilli Daniel , Matecki Stefan , Wysocki Marc , Eledjam Jean-Jacques , Brochard Laurent 
Published: February 2009

Background
Dual-control modes of ventilation adapt the pressure delivery to keep a volume target in response to changes in respiratory mechanics, but they may respond poorly to changes in ventilatory demand. Adaptive support ventilation (ASV), a complex minute volume-targeted pressure-regulated ventilation, was compared to adaptive pressure ventilation (APV), a dual-mode in which the pressure level is adjusted to deliver a preset tidal volume, and to pressure support ventilation (PSV) when facing an increase in ventilatory demand.

Methods
A total of 14 intensive care unit patients being weaned off mechanical ventilation were included in this randomized crossover study. The effect of adding a heat-and-moisture exchanger to augment circuit dead space was assessed with a same fixed level of ASV, PSV, and APV.

Results
Arterial blood gases, ventilator response, and patient respiratory effort parameters were evaluated at the end of the six periods. Adding dead space significantly increased minute ventilation and PaCO2 values with the three modes. Indexes of respiratory effort (pressure-time index of respiratory muscles and work of breathing) increased with all ventilatory modes after dead-space augmentation. This increase was significantly greater with APV than with PSV or ASV (P < 0.05). The assistance delivered during APV decreased significantly with dead-space from 12.7 +/- 2.6 to 6.7 +/- 1.4 cm H2O, whereas no change occurred with ASV and PSV.

Conclusions
ASV and PSV behaved differently but ended up with similar pressure level facing acute changes in ventilatory demand, by contrast to APV (a simple volume-guaranteed pressure-control mode), in which an increase in ventilatory demand results in a decrease in the pressure support provided by the ventilator.
Comparative Effects of Halogenated Inhaled Anesthetics on Voltage-gated Na+Channel Function
Authors: Ouyang Wei , Herold Karl F. , Hemmings Hugh C. 
Published: February 2009

Background
Inhibition of voltage-gated Na channels (Na(v)) is implicated in the synaptic actions of volatile anesthetics. We studied the effects of the major halogenated inhaled anesthetics (halothane, isoflurane, sevoflurane, enflurane, and desflurane) on Na(v)1.4, a well-characterized pharmacological model for Na(v) effects.

Methods
Na currents (I(Na)) from rat Na(v)1.4 alpha-subunits heterologously expressed in Chinese hamster ovary cells were analyzed by whole cell voltage-clamp electrophysiological recording.

Results
Halogenated inhaled anesthetics reversibly inhibited Na(v)1.4 in a concentration- and voltage-dependent manner at clinical concentrations. At equianesthetic concentrations, peak I(Na) was inhibited with a rank order of desflurane > halothane approximately enflurane > isoflurane approximately sevoflurane from a physiologic holding potential (-80 mV). This suggests that the contribution of Na channel block to anesthesia might vary in an agent-specific manner. From a hyperpolarized holding potential that minimizes inactivation (-120 mV), peak I(Na) was inhibited with a rank order of potency for tonic inhibition of peak I(Na) of halothane > isoflurane approximately sevoflurane > enflurane > desflurane. Desflurane produced the largest negative shift in voltage-dependence of fast inactivation consistent with its more prominent voltage-dependent effects. A comparison between isoflurane and halothane showed that halothane produced greater facilitation of current decay, slowing of recovery from fast inactivation, and use-dependent block than isoflurane.

Conclusions
Five halogenated inhaled anesthetics all inhibit a voltage-gated Na channel by voltage- and use-dependent mechanisms. Agent-specific differences in efficacy for Na channel inhibition due to differential state-dependent mechanisms creates pharmacologic diversity that could underlie subtle differences in anesthetic and nonanesthetic actions.
Development and Validation of an Acute Kidney Injury Risk Index for Patients Undergoing General Surgery
Authors: Kheterpal Sachin , Tremper Kevin K. , Heung Michael , Rosenberg Andrew L. , Englesbe Michael , Shanks Amy M. , Campbell Darrell A. 
Published: February 2009

Background
The authors sought to identify the incidence, risk factors, and mortality impact of acute kidney injury (AKI) after general surgery using a large and representative national clinical data set.

Methods
The 2005-2006 American College of Surgeons-National Surgical Quality Improvement Program participant use data file is a compilation of outcome data from general surgery procedures performed in 121 US medical centers. The primary outcome was AKI within 30 days, defined as an increase in serum creatinine of at least 2 mg/dl or acute renal failure necessitating dialysis. A variety of patient comorbidities and operative characteristics were evaluated as possible predictors of AKI. A logistic regression full model fit was used to create an AKI model and risk index. Thirty-day mortality among patients with and without AKI was compared.

Results
Of 152,244 operations reviewed, 75,952 met the inclusion criteria, and 762 (1.0%) were complicated by AKI. The authors identified 11 independent preoperative predictors: age 56 yr or older, male sex, emergency surgery, intraperitoneal surgery, diabetes mellitus necessitating oral therapy, diabetes mellitus necessitating insulin therapy, active congestive heart failure, ascites, hypertension, mild preoperative renal insufficiency, and moderate preoperative renal insufficiency. The c statistic for a simplified risk index was 0.80 in the derivation and validation cohorts. Class V patients (six or more risk factors) had a 9% incidence of AKI. Overall, patients experiencing AKI had an eightfold increase in 30-day mortality.

Conclusions
Approximately 1% of general surgery cases are complicated by AKI. The authors have developed a robust risk index based on easily identified preoperative comorbidities and patient characteristics.
Development of the Functional Recovery Index for Ambulatory Surgery and Anesthesia
Authors: Wong Jean , Tong Doris , De Silva Yoshani , Abrishami Amir , Chung Frances 
Published: February 2009

Background
It is increasingly important to evaluate patients' recovery after ambulatory surgery. The authors developed the Functional Recovery Index (FRI) to assess postdischarge functional recovery for ambulatory surgical patients.

Methods
The scale development involved four phases: item generation, item selection, reliability, and validity testing. A draft questionnaire was tested and revised. Items were selected through testing endorsement frequency, factor analysis, and testing internal consistency. The interrater reliability was calculated. Construct validity was tested by multiple hypotheses on convergent validity, extreme groups, and discriminant validity. Responsiveness was assessed by measuring the FRI postoperatively and comparing minor versus more extensive surgery. The rate of response and the time for completion of the questionnaire were recorded.

Results
The final questionnaire had 14 items grouped under 3 factors. Each item was scored from 0 to 10, with 0 = no difficulty and 10 = extreme difficulty with the activity. The 3 factors were summated for a total score. Internal consistency for the 3 factors (pain and social activity, lower limb activity, and general physical activity) was as follows: Cronbach alpha = 0.90, 0.89, and 0.86, respectively. Interrater reliability was 0.99. Convergent validity for FRI versus verbal rating scale pain score was 0.76. Discriminant validity testing showed that the type of surgery was significant and that intermediate (beta = 0.138) and major surgery (beta = 0.337) were associated with higher FRI scores than minor surgery. The time to complete the questionnaires ranged between 4 min 10 s and 4 min 35 s.

Conclusions
The FRI had excellent reliability, good validity, responsiveness, and acceptability, indicating that this questionnaire will be a good instrument for assessing functional recovery of ambulatory surgical patients.
Anesthesiology Trainees Face Ethical, Practical, and Relational Challenges in Obtaining Informed Consent
Authors: Waisel David B. , Lamiani Giulia , Sandrock Norma J. , Pascucci Robert , Truog Robert D. , Meyer Elaine C. 
Published: February 2009

Background
Categorizing difficulties anesthesiologists have in obtaining informed consent may influence education, performance, and research. This study investigated the trainees' perspectives and educational needs through a qualitative analysis of narratives.

Methods
The Program to Enhance Relational and Communication Skills-Anesthesia used professional actors to teach communication skills and relational abilities associated with informed consent. Before attending the program, participants wrote about a challenging informed consent experience. Narratives were analyzed by two researchers following the principles of grounded theory. The researchers independently read the narratives and marked key words and phrases to identify reoccurring challenges described by anesthesiologists. Through rereading of the narratives and discussion, the two researchers reached consensus on the challenges that arose and calculated their frequency.

Results
Analysis of the 39 narratives led to the identification of three types of challenges facing anesthesiologists in obtaining informed consent. Ethical challenges included patient wishes not honored, conflict between patient and family wishes and medical judgment, patient decision-making capacity, and upholding professional standards. Practical challenges included the amount of information to provide, communication barriers, and time limitations. Relational challenges included questions about trainee competence, mistrust associated with previous negative experiences, and misunderstandings between physician and patient or family.

Conclusions
The ethical, practical, and relational challenges in obtaining informed consent colored trainees' views of patient care and affected their interactions with patients. Using participant narratives personalizes education and motivates participants. The richness of narratives may help anesthesiologists to appreciate the qualitative aspects of informed consent.