bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurocognitive Performance in Hypertensive Patients after Spine Surgery
Authors: Yocum Gene T. , Gaudet John G. , Teverbaugh Lauren A. , Quest Donald O. , McCormick Paul C. , Connolly E Sander , Heyer Eric J. 
Published: January 2009

Background
Cognitive dysfunction is fairly common after noncardiac surgery and may be related to intraoperative blood pressure management. The authors present an analysis of risk factors for cognitive deterioration after spine surgery in older patients, with particular emphasis on intraoperative blood pressure in normotensive and hypertensive patients.

Methods
This is a post hoc cohort analysis of 45 patients enrolled before undergoing lumbar laminectomy or microdiscectomy. The patients underwent a battery of 5 neuropsychometric tests preoperatively, and 1 day and 1 month postoperatively. Computerized anesthesia records were used to obtain intraoperative mean arterial pressure (MAP) data. Simple linear regressions between intraoperative MAP and postoperative cognitive performance were performed, and multivariate linear regression models of postoperative cognitive performance were constructed to analyze potential risk factors for cognitive decline after surgery.

Results
Twenty-one normotensive patients (mean age, 62.4 yr) and 24 hypertensive patients (mean age, 67.9 yr) were included in this analysis. There was a significant positive relationship between minimum intraoperative MAP values and 1-day cognitive performance by simple linear regression in hypertensive (P = 0.003), but not normotensive, patients. In multivariate linear regression analysis of cognitive performance, there was a significant interaction between hypertension and minimum intraoperative MAP at 1 day and 1 month.

Conclusions
In hypertensive patients, there was a significant relationship between minimum intraoperative MAP and decline in cognitive function 1 day and 1 month after surgery. A prospective controlled trial of intraoperative blood pressure control, especially during induction of anesthesia when MAP values typically drop, is needed to confirm these findings.
Critical Closing Pressure as the Arterial Downstream Pressure with the Heart Beating and during Circulatory Arrest
Authors: Kottenberg-Assenmacher Eva , Aleksic Ivan , Eckholt Mareike , Lehmann Nils , Peters Jürgen 
Published: January 2009

Background
Calculation of systemic vascular resistance, used for hemodynamic decision-making, is based on central venous pressure taken as the downstream pressure. However, during circulatory arrest, arterial pressure decreases to a plateau higher than central venous pressure, the critical closing pressure (Pcrit). The authors assessed in humans undergoing arrest whether two-compartment and pressure-dependent conductivity models better estimate arterial pressure decay and Pcrit than a single-compartment model, and whether Pcrit corresponds to Pcrit calculated with the heart beating.

Methods
Aortic pressure decay was fitted to single-compartment, two-compartment, and pressure-dependent conductivity models using specified time intervals during arrest and natural diastole in 10 patients during defibrillator implantation.

Results
Although all models closely predicted Pcrit with an arrest of > or = 7s, both two-compartment and pressure-dependent conductivity models better estimated pressure decay than a single-compartment model. However, Pcrit calculated from natural diastolic pressure decay was greater (53 mmHg +/- 15.6) than Pcrit 15 s (26.6 mmHg +/- 7.8, P = 0.001) and 30 s (23.9 mmHg +/- 7.1, P = 0.001) during arrest, and also greater than Pcrit calculated for the same time interval during initial arrest.

Conclusions
Thus, during arrest, Pcrit can be closely predicted after > or = 7 s, regardless of the model; two-compartment and pressure-dependent conductivity models provide a better fit than a single-compartment model, and actual Pcrit is much less than Pcrit calculated with the heart beating. Irrespective of uncertainties in whether Pcrit calculated with the heart beating or during arrest is the "true" Pcrit prevailing physiologically, linear vascular resistance is markedly less when substituting Pcrit for central venous pressure as the downstream pressure.
Role of Heat Shock Protein 90 and Endothelial Nitric Oxide Synthase during Early Anesthetic and Ischemic Preconditioning
Authors: Amour Julien , Brzezinska Anna K. , Weihrauch Dorothee , Billstrom Amie R. , Zielonka Jacek , Krolikowski John G. , Bienengraeber Martin W. , Warltier David C. , Pratt Philip F. , Kersten Judy R. 
Published: January 2009

Background
Nitric oxide is known to be essential for early anesthetic preconditioning (APC) and ischemic preconditioning (IPC) of myocardium. Heat shock protein 90 (Hsp90) regulates endothelial nitric oxide synthase (eNOS) activity. In this study, the authors tested the hypothesis that Hsp90-eNOS interactions modulate APC and IPC.

Methods
Myocardial infarct size was measured in rabbits after coronary occlusion and reperfusion in the absence or presence of preconditioning within 30 min of isoflurane (APC) or 5 min of coronary artery occlusion (IPC), and with or without pretreatment with geldanamycin or radicicol, two chemically distinct Hsp90 inhibitors, or N-nitro-L-arginine methyl ester, a nonspecific nitric oxide synthase NOS inhibitor. Isoflurane-dependent nitric oxide production was measured (ozone chemiluminescence) in human coronary artery endothelial cells or mouse cardiomyocytes, in the absence or presence of Hsp90 inhibitors or N-nitro-L-arginine methyl ester. Interactions between Hsp90 and eNOS, and eNOS activation, were assessed with immunoprecipitation, immunoblotting, and confocal microscopy.

Results
APC and IPC decreased infarct size (by 50% and 59%, respectively), and this action was abolished by Hsp90 inhibitors. N-nitro-L-arginine methyl ester blocked APC but not IPC. Isoflurane increased nitric oxide production in human coronary artery endothelial cells concomitantly with an increase in Hsp90-eNOS interaction (immunoprecipitation, immunoblotting, and immunohistochemistry). Pretreatment with Hsp90 inhibitors abolished isoflurane-dependent nitric oxide production and decreased Hsp90-eNOS interactions. Isoflurane did not increase nitric oxide production in mouse cardiomyocytes, and eNOS was below the level of detection.

Conclusion
The results indicate that Hsp90 plays a critical role in mediating APC and IPC through protein-protein interactions, and suggest that endothelial cells are important contributors to nitric oxide-mediated signaling during APC.
Propofol and Midazolam Inhibit Conscious Memory Processes Very Soon after Encoding: An Event-related Potential Study of Familiarity and Recollection in Volunteers
Authors: Veselis Robert A. , Pryor Kane O. , Reinsel Ruth A. , Li Yuelin , Mehta Meghana , Johnson Ray 
Published: January 2009

Background
Intravenous drugs active via gamma-aminobutyric acid receptors to produce memory impairment during conscious sedation. Memory function was assessed using event-related potentials (ERPs) while drug was present.

Methods
The continuous recognition task measured recognition of photographs from working (6 s) and long-term (27 s) memory while ERPs were recorded from Cz (familiarity recognition) and Pz electrodes (recollection recognition). Volunteer participants received sequential doses of one of placebo (n = 11), 0.45 and 0.9 microg/ml propofol (n = 10), 20 and 40 ng/ml midazolam (n = 12), 1.5 and 3 microg/ml thiopental (n = 11), or 0.25 and 0.4 ng/ml dexmedetomidine (n = 11). End-of-day yes/no recognition 225 min after the end of drug infusion tested memory retention of pictures encoded on the continuous recognition tasks.

Results
Active drugs increased reaction times and impaired memory on the continuous recognition task equally, except for a greater effect of midazolam (P < 0.04). Forgetting from continuous recognition tasks to end of day was similar for all drugs (P = 0.40), greater than placebo (P < 0.001). Propofol and midazolam decreased the area between first presentation (new) and recognized (old, 27 s later) ERP waveforms from long-term memory for familiarity (P = 0.03) and possibly for recollection processes (P = 0.12). Propofol shifted ERP amplitudes to smaller voltages (P < 0.002). Dexmedetomidine may have impaired familiarity more than recollection processes (P = 0.10). Thiopental had no effect on ERPs.

Conclusion
Propofol and midazolam impaired recognition ERPs from long-term memory but not working memory. ERP measures of memory revealed different pathways to end-of-day memory loss as early as 27 s after encoding.
α-1-Adrenergic Receptor Agonist Activity of Clinical α-Adrenergic Receptor Agonists Interferes with α-2-Mediated Analgesia
Authors: Gil Daniel W. , Cheevers Cynthia V. , Kedzie Karen M. , Manlapaz Cynthia A. , Rao Sandhya , Tang Elaine , Donello John E. 
Published: January 2009

Background
The use of alpha-2 adrenergic agonists for analgesia is limited due to a narrow therapeutic window. Definition of the role of alpha receptor subtypes in alpha agonist mediated analgesia may identify strategies to separate the analgesic from sedative and cardiovascular effects.

Methods
Analgesic activity of brimonidine, clonidine, and tizanidine was investigated in wild-type C57B/6, alpha-2A, and alpha-2C knockout mice with allodynia induced by N-methyl-D-aspartate or sulprostone. The alpha receptor selectivity of the alpha agonists was assessed using functional in vitro recombinant assays.

Results
Brimonidine, clonidine, and tizanidine reduced N-methyl-D-aspartate- and sulprostone-induced allodynia in wild-type mice, but not alpha-2A knockout mice. In alpha-2C knockout mice, brimonidine and tizanidine reduced allodynia in both models, whereas clonidine only reduced N-methyl-D-aspartate-induced allodynia. In vitro, clonidine and tizanidine activated alpha-1 and alpha-2 receptors with similar potencies, whereas brimonidine was selective for alpha-2 receptors. In alpha-2C knockout mice with sulprostone-induced allodynia, blockade of clonidine's alpha-1 receptor agonist activity restored clonidine's analgesic efficacy. In wild-type mice, the analgesic potency of intrathecal clonidine and tizanidine was increased 3- to 10-fold by coadministration with the alpha-1A-selective antagonist 5-methylurapidil without affecting sedation. Following intraperitoneal administration, the therapeutic window was negligible for clonidine and tizanidine, but greater for brimonidine. 5-Methylurapidil enhanced the therapeutic window of intraperitoneal clonidine and tizanidine approximately 10-fold.

Conclusions
Alpha-1A receptor agonist activity can counterbalance alpha-2 receptor agonist-induced analgesia. Greater alpha-2 selectivity may enhance the therapeutic window of alpha-2 agonists in the treatment of pain.
Factor XIII Substitution in Surgical Cancer Patients at High Risk for Intraoperative Bleeding
Authors: Korte Wolfgang C. , Szadkowski Christine , Gähler Anita , Gabi Konrad , Kownacki Edward , Eder Monika , Degiacomi Priska , Zoller Norbert , Devay Jan , Lange Jochen , Schnider Thomas 
Published: January 2009

Background
Excessive intraoperative bleeding is associated with significant morbidity and mortality. The authors and others have shown that fibrin monomer allows preoperative risk stratification for intraoperative blood loss, likely due to an imbalance between available factor XIII and prothrombin conversion. The authors hypothesized that the use of factor XIII would delay the decrease of clot firmness in high-risk patients.

Methods
The concept was tested in a prospective, randomized, double-blind, placebo-controlled trial in elective gastrointestinal cancer surgery. Patients were randomized to receive factor XIII (30 U/kg) or placebo in addition to controlled standard therapy.

Results
Twenty-two patients were evaluable for a planned interim analysis. For the primary outcome parameter maximum clot firmness, patients receiving factor XIII showed a nonsignificant 8% decrease, and patients receiving placebo lost 38%, a highly significantly difference between the two groups (P = 0.004). A reduction in the nonprimary outcome parameters fibrinogen consumption (-28%, P = 0.01) and blood loss (-29%, P = 0.041) was also observed in the factor XIII group. Three patients experienced adverse events that seemed unrelated to factor XIII substitution. The trial was stopped early after a planned interim analysis with the primary endpoint reached.

Conclusions
This proof of concept study confirms the hypothesis that patients at high risk for intraoperative blood loss show reduced loss of clot firmness when factor XIII is administered early during surgery. Further clinical trials are needed to assess relevant clinical endpoints such as blood loss, loss of other coagulation factors, and use of blood products.
Perioperative Ischemic Optic Neuropathy
Authors: Holy Sarah E. , Tsai Jonathan H. , McAllister Russell K. , Smith Kyle H. 
Published: January 2009

Background
Ischemic optic neuropathy is the most common cause of perioperative vision loss. The authors sought to determine its incidence and identify risk factors that may contribute to perioperative ischemic optic neuropathy associated with nonophthalmologic surgical procedures at their institution.

Methods
Seventeen patients who experienced perioperative ischemic optic neuropathy were included in a retrospective chart review case-control study. The authors matched each patient with two control patients who had a similar surgical procedure but did not lose vision. They analyzed multiple perioperative variables for the case and control groups.

Results
From among 126,666 surgical procedures performed during the study period, the authors identified 17 patients with perioperative ischemic optic neuropathy, yielding an overall incidence of 0.013%. There were no hemodynamic variables that differed significantly between the ischemic optic neuropathy patients and the matched control patients.

Conclusion
The authors conclude that perioperative ischemic optic neuropathy can occur in the absence of atypical fluctuations in hemodynamic variables during the perioperative period.
Binding of Long-lasting Local Anesthetics to Lipid Emulsions
Authors: Mazoit Jean-Xavier , Le Guen Régine , Beloeil Hélène , Benhamou Dan 
Published: January 2009

Background
Rapid infusion of lipid emulsion has been proposed to treat local anesthetic toxicity. The authors wanted to test the buffering properties of two commercially available emulsions made of long- and of long- and medium-chain triglycerides.

Methods
Using the shake-flask method, the authors measured the solubility and binding of racemic bupivacaine, levobupivacaine, and ropivacaine to diluted Intralipid (Fresenius Kabi, Paris, France) and Medialipide (B-Braun, Boulogne, France).

Results
The apparent distribution coefficient expressed as the ratio of mole fraction was 823 +/- 198 and 320 +/- 65 for racemic bupivacaine and levobupivacaine, and ropivacaine, respectively, at 500 mg in the Medialipide/buffer emulsion; and 1,870 +/- 92 and 1,240 +/- 14 for racemic bupivacaine and levobupivacaine, and ropivacaine, respectively, in the Intralipid/buffer emulsion. Decreasing the pH from 7.40 to 7.00 of the Medialipide/buffer emulsion led to a decrease in ratio of molar concentration from 121 +/- 3.8 to 46 +/- 2.8 for bupivacaine, and to a lesser extent from 51 +/- 4.0 to 31 +/- 1.6 for ropivacaine. The capacity of the 1% emulsions was 871 and 2,200 microM for the 1% Medialipide and Intralipid emulsions, respectively. The dissociation constant was 818 and 2,120 microM for racemic bupivacaine and levobupivacaine, and ropivacaine, respectively. Increasing the temperature from 20 to 37 degrees C led to a greater increase in affinity for ropivacaine (55%) than for bupivacaine (27%). When the pH of the buffer was decreased from 7.40 to 7.00, the affinity was decreased by a factor of 1.68, similar for both anesthetics.

Conclusions
The solubility of long-acting local anesthetics in lipid emulsions and the high capacity of binding of these emulsions most probably explain their clinical efficacy in case of toxicity. The long-chain triglyceride emulsion Intralipid appears to be about 2.5 times more efficacious than the 50/50 medium-chain/long-chain Medialipide emulsion. Also, because of their higher hydrophobicity, racemic bupivacaine and levobupivacaine seem to clear more rapidly than ropivacaine.
Perioperative Acute Ischemic Stroke in Noncardiac and Nonvascular Surgery
Authors: Bateman Brian T. , Schumacher H Christian , Wang Shuang , Shaefi Shahzad , Berman Mitchell F. 
Published: January 2009

Background
Perioperative acute ischemic stroke (AIS) is a recognized complication of noncardiac, nonvascular surgery, but few data are available regarding incidence and effect on outcome. This study examines the epidemiology of perioperative AIS in three common surgeries: hemicolectomy, total hip replacement, and lobectomy/segmental lung resection.

Methods
Discharges for patients aged 18 yr or older who underwent any of the surgical procedures listed above were extracted from the Nationwide Inpatient Sample, an administrative database that contains 20% of all discharges from non-Federal hospitals each year, for years 2000 to 2004. Using appropriate International Classification of Diseases, 9th revision, Clinical Modification codes, patients with perioperative AIS were identified, as were comorbid conditions that may be risk factors for perioperative AIS. Multivariate logistic regression was performed to identify independent predictors of perioperative AIS and to ascertain the effect of AIS on outcome.

Results
A total of 0.7% of 131,067 hemicolectomy patients, 0.2% of 201,235 total hip replacement patients, and 0.6% of 39,339 lobectomy/segmental lung resection patients developed perioperative AIS. For patients older than 65 yr, AIS rose to 1.0% for hemicolectomy, 0.3% for hip replacement, and 0.8% for pulmonary resection. Multivariate logistic regression analysis revealed renal disease (odds ratio, 3.0), atrial fibrillation (odds ratio, 2.0), history of stroke (odds ratio, 1.6), and cardiac valvular disease (odds ratio, 1.5) to be the most significant risk factors for perioperative AIS.

Conclusions
Perioperative AIS is an important source of morbidity and mortality associated with noncardiac, nonvascular surgery, particularly in elderly patients and patients with atrial fibrillation, valvular disease, renal disease, or previous stroke.
Reversal of Rocuronium-induced Neuromuscular Blockade with Sugammadex in Pediatric and Adult Surgical Patients
Authors: Plaud Benoît , Meretoja Olli , Hofmockel Rainer , Raft Julien , Stoddart Peter A. , van Kuijk Jacqueline H. M. , Hermens Yvonne , Mirakhur Rajinder K. 
Published: January 2009

Background
Sugammadex reverses neuromuscular blockade by chemical encapsulation of rocuronium. This phase IIIA study explored efficacy and safety of sugammadex in infants (28 days to 23 months), children (2-11 yr), adolescents (12-17 yr), and adults (18-65 yr).

Methods
Anesthetized patients (American Society of Anesthesiologists class 1-2) received 0.6 mg/kg rocuronium and were randomized to receive sugammadex (0.5, 1.0, 2.0, or 4.0 mg/kg) or placebo at reappearance of T2. Neuromuscular monitoring was performed using acceleromyography. Primary endpoint was time from sugammadex/placebo administration to recovery of the train-of-four ratio to 0.9. Adverse events and electrocardiograms were recorded, and blood samples were collected for safety and determination of sugammadex and rocuronium plasma concentrations.

Results
A dose-response relation was demonstrated in children (n = 22), adolescents (n = 28), and adults (n = 26), but not infants because of the small sample size (n = 8). After placebo, median recovery time of train-of-four to 0.9 was 21.0, 19.0, 23.4, and 28.5 min in infants, children, adolescents, and adults, respectively. After 2.0 mg/kg sugammadex train-of-four 0.9 was attained in 0.6, 1.2, 1.1, and 1.2 min, respectively. The sugammadex plasma concentrations were similar for the children, adolescent, and adult age groups across the dose range. Sugammadex was well tolerated: No reoccurrence of blockade, inadequate reversal, significant QT prolongation, or other abnormalities were observed.

Conclusions
Sugammadex is a new reversal agent that rapidly, effectively, safely, and with similar recovery times reverses rocuronium-induced neuromuscular blockade in children, adolescents, adults, and the small number of infants studied.
High Body Mass Index Is a Weak Predictor for Difficult and Failed Tracheal Intubation
Authors: Lundstrøm Lars H. , Møller Ann M. , Rosenstock Charlotte , Astrup Grethe , Wetterslev Jørn 
Published: January 2009

Background
Previous studies have failed to detect high body mass index (BMI) as a risk factor for difficult tracheal intubation (DTI). BMI was investigated as a risk factor for DTI in patients planned for direct laryngoscopy.

Methods
A cohort of 91,332 consecutive patients planned for intubation by direct laryngoscopy was retrieved from the Danish Anesthesia Database. A four-point scale to grade the tracheal intubation was used. Age, sex, American Society of Anesthesiologists physical status classification, priority of surgery, history of previous DTI, modified Mallampati-score, use of neuromuscular blocker, and BMI were retrieved. Logistic regression to assess whether BMI was associated with DTI was performed.

Results
The frequency of DTI was 5.2% (95% confidence interval [CI] 5.0-5.3). In multivariate analyses adjusted for other significant covariates, BMI of 35 or more was a risk for DTI with an odds ratio of 1.34 (95% CI 1.19-1.51, P < 0.0001). As a stand alone test, BMI of 35 or more predicted DTI with a sensitivity of 7.5% (95% CI 7.3-7.7%) and with a predictive value of a positive test of 6.4% (95% CI 6.3-6.6%). BMI as a continuous covariate was a risk for failed intubation with an odds ratio of 1.031 (95% CI 1.002-1.061, P < 0.04).

Conclusions
High BMI is a weak but statistically significant predictor of difficult and failed intubation and may be more appropriate than weight in multivariate models of prediction of DTI.
Effects of Different Levels of Pressure Support Variability in Experimental Lung Injury
Authors: Spieth Peter M. , Carvalho Alysson R. , Güldner Andreas , Pelosi Paolo , Kirichuk Oleg , Koch Thea , de Abreu Marcelo Gama 
Published: January 2009

Background
Noisy pressure support ventilation has been reported to improve respiratory function compared to conventional assisted mechanical ventilation. We aimed at determining the optimal level of pressure support variability during noisy pressure support ventilation.

Methods
Twelve pigs were anesthetized and mechanically ventilated. Acute lung injury was induced by surfactant depletion. At four levels of pressure support variability (coefficients of variation of pressure support equal to 7.5, 15, 30, and 45%, 30 min each, crossover design, special Latin squares sequence), we measured respiratory variables, gas exchange, hemodynamics, inspiratory effort, and comfort of breathing. The mean level of tidal volume was constant among variability levels.

Results
Compared to conventional pressure support ventilation, different levels of variability in pressure support improved the elastance of the respiratory system, peak airway pressure, oxygenation, and intrapulmonary shunt. Oxygenation and venous admixture benefited more from intermediate (30%) levels of variability, whereas elastance and peak airway pressure improved linearly with increasing variability. Heart rate as well as mean arterial and pulmonary arterial pressures decreased slightly at intermediate to high (30-45%) levels of variability in pressure support. Inspiratory effort and comfort of breathing were not importantly influenced by increased variability in pressure support.

Conclusion
In a surfactant depletion model of acute lung injury, variability of pressure support improves lung function. The variability level of 30% seems to represent a reasonable compromise to improve lung functional variables during noisy pressure support ventilation.