bluuebunny/crossref_metadata_2025 huggingface dataset:
Choice of Primary Anesthetic Regimen Can Influence Intensive Care Unit Length of Stay after Coronary Surgery with Cardiopulmonary Bypass
Authors: De Hert Stefan G. , Van der Linden Philippe J. , Cromheecke Stefanie , Meeus Roel , ten Broecke Pieter W. , De Blier Ivo G. , Stockman Bernard A. , Rodrigus Inez E.
Published: June 2004

Background

Volatile anesthetics protect the myocardium during coronary surgery. This study hypothesized that the use of a volatile agent in the anesthetic regimen would be associated with a shorter intensive care unit (ICU) and hospital length of stay (LOS), compared with a total intravenous anesthetic regimen.

Methods

Elective coronary surgery patients were randomly assigned to receive propofol (n = 80), midazolam (n = 80), sevoflurane (n = 80), or desflurane (n = 80) as part of a remifentanil-based anesthetic regimen. Multiple logistic regression analysis was used to identify the independent variables associated with a prolonged ICU LOS.

Results

Patient characteristics were similar in all groups. ICU and hospital LOS were lower in the sevoflurane and desflurane groups (P < 0.01). The number of patients who needed a prolonged ICU stay (> 48 h) was also significantly lower (propofol: n = 31; midazolam: n = 34; sevoflurane: n = 10; desflurane: n = 15; P < 0.01). Occurrence of atrial fibrillation, a postoperative troponin I concentration greater than 4 ng/ml, and the need for prolonged inotropic support (> 12 h) were identified as the significant risk factors for prolonged ICU LOS. Postoperative troponin I concentrations and need for prolonged inotropic support were lower in the sevoflurane and desflurane group (P < 0.01). Postoperative cardiac function was also better preserved with the volatile anesthetics. The incidence of other postoperative complications was similar in all groups.

Conclusions

The use of sevoflurane and desflurane resulted in a shorter ICU and hospital LOS. This seemed to be related to a better preservation of early postoperative myocardial function.
Spectral Entropy as an Electroencephalographic Measure of Anesthetic Drug Effect
Authors: Vanluchene Ann L.G. , Vereecke Hugo , Thas Olivier , Mortier Eric P. , Shafer Steven L. , Struys Michel M.R.F.
Published: June 2004

Background

The authors compared the behavior of two calculations of electroencephalographic spectral entropy, state entropy (SE) and response entropy (RE), with the A-Line ARX Index (AAI) and the Bispectral Index (BIS) and as measures of anesthetic drug effect. They compared the measures for baseline variability, burst suppression, and prediction probability. They also developed pharmacodynamic models relating SE, RE, AAI, and BIS to the calculated propofol effect-site concentration (Ceprop).

Methods

With institutional review board approval, the authors studied 10 patients. All patients received 50 mg/min propofol until either burst suppression greater than 80% or mean arterial pressure less than 50 mmHg was observed. SE, RE, AAI, and BIS were continuously recorded. Ceprop was calculated from the propofol infusion profile. Baseline variability, prediction of burst suppression, prediction probability, and Spearman rank correlation were calculated for SE, RE, AAI, and BIS. The relations between Ceprop and the electroencephalographic measures of drug effect were estimated using nonlinear mixed effect modeling.

Results

Baseline variability was lowest when using SE and RE. Burst suppression was most accurately detected by spectral entropy. Prediction probability and individualized Spearman rank correlation were highest for BIS and lowest for SE. Nonlinear mixed effect modeling generated reasonable models relating all four measures to Ceprop.

Conclusions

Compared with BIS and AAI, both SE and RE seem to be useful electroencephalographic measures of anesthetic drug effect, with low baseline variability and accurate burst suppression prediction. The ability of the measures to predict Ceprop was best for BIS.
Can Bispectral Index Monitoring Predict Recovery of Consciousness in Patients with Severe Brain Injury?
Authors: Fàbregas Neus , Gambús Pedro L. , Valero Ricard , Carrero Enrique J. , Salvador Lydia , Zavala Elysabeth , Ferrer Enrique
Published: June 2004

Background

The probability of recovering consciousness in acute brain-injured patients depends on central nervous system damage and complications acquired during their stay in the intensive care unit. The objective of this study was to establish a relation between the Bispectral Index (BIS) and other variables derived from the analysis of the electroencephalographic signal, with the probability of recovering consciousness in patients in a coma state due to severe cerebral damage.

Methods

Twenty-five critically ill, unconscious brain-injured patients from whom sedative drugs were withdrawn at least 24 h before BIS recording were prospectively studied. BIS, 95% spectral edge frequency, burst suppression ratio, and frontal electromyography were recorded for 20 min. The neurologic condition of the patients was measured according to the Glasgow Coma Score (GCS). Patients were followed up for assessment of recovery of consciousness for 6 months after the injury. The studied variables were compared between the group of patients who recovered consciousness and those who did not recover. Their predictive ability was evaluated by means of the Pk statistic. Univariate and multivariate logistic regression was used to model the relation between variables and probability of recovery of consciousness. Cross-validation was used to validate the proposed model.

Results

There were statistically significant differences between the group of patients who recovered consciousness and those who did not with respect to BISmax, BISmin, BISmean, and BISrange, frontal electromyography, signal quality index values, and GCSBIS. The Pk (SE) values were 0.99 (0.01) for electromyelography, 0.96 (0.05) for BISmax, 0.92 (0.05) for BISmean, 0.92 (0.06) for BISrange, and 0.82 (0.09) for GCSBIS. The odds ratio for BISmax in the logistic regression model was 1.17 (95% confidence interval, 1.1-1.35). Cross-validation results reported a high-accuracy median absolute cross-validation performance error of 3.06% (95% confidence interval, 1-22.15%) and a low-bias median cross-validation performance error of 0.84% (0.56-2.12%).

Conclusions

The study BIS and other electrophysiologic and clinical variables has enabled construction and cross-validation of a model relating BIS(max) to the probability of recovery of consciousness in patients in a coma state due to a severe brain injury, after sedation has been withdrawn.
Effect of Mechanical Ventilation on Cytokine Response to Intratracheal Lipopolysaccharide
Authors: Whitehead Thomas C. , Zhang Haibo , Mullen Brendan , Slutsky Arthur S.
Published: June 2004

Background

Mechanical ventilation may cause lung injury through the excitation of an inflammatory response and the release of mediators, such as cytokines. The authors tested the hypothesis that intratracheal lipopolysaccharide amplifies the cytokine response to mechanical ventilation.

Methods

Rat lungs were intratracheally instilled with lipopolysaccharide followed by ex vivo mechanical ventilation for 2 h with low tidal volume of 7 ml/kg with 3 cm H2O positive end-expiratory pressure (PEEP), high tidal volume of 40 ml/kg with zero PEEP, medium tidal volume of 15 ml/kg with 3 cm H2O PEEP, or medium tidal volume and zero PEEP.

Results

In the absence of lipopolysaccharide, lung lavage concentrations of tumor necrosis factor and interleukin 1 beta but not macrophage inflammatory protein 2 were significantly higher in lungs ventilated at high tidal volume/zero PEEP than at low tidal volume. There was a marked increase in lavage tumor necrosis factor and macrophage inflammatory protein 2 concentrations in lungs ventilated at low tidal volume after exposure to intratracheal lipopolysaccharide at doses of 100 ng/ml or greater. However, in lungs ventilated at high tidal volume, this response to lipopolysaccharide was markedly reduced. In addition, the number of alveolar macrophages recovered in the lavage was significantly lower in lungs ventilated at high tidal volume.

Conclusion

Ventilation strategy can modify lung cytokine responses to lipopolysaccharide, likely through an effect on the alveolar macrophage population.
Effects on Synaptic Inhibition in the Hippocampus Do Not Underlie the Amnestic and Convulsive Properties of the Nonimmobilizer 1,2-Dichlorohexafluorocyclobutane
Authors: Perouansky Misha , Pearce Robert A.
Published: June 2004

Background

Although it does not suppress movement in response to noxious stimuli, the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, also known as 2N) does cause amnesia and seizures. These occur at 0.48 and 1.3 times, respectively, the concentrations that are predicted from its lipid solubility to cause immobility. The molecular and cellular basis of these effects is not known. The ionotropic gamma-aminobutyric acid type A (GABAA) receptor is modulated strongly by anesthetics, and it plays an important role in many seizure models. Also, the hippocampus is a structure central to the formation of memory and is susceptible to seizure generation. The authors therefore investigated the effect of F6 on GABAA receptor- mediated inhibition in hippocampal neurons.

Methods

Transverse hippocampal slices were prepared from young (12- to 21-day-old) Sprague-Dawley rats. Inhibitory postsynaptic currents were recorded from hippocampal CA1 pyramidal cells in the presence of ionotropic glutamate receptor antagonists. F6 was applied with the bath solution. The concentration of F6 achieved during the experiment at the location of synaptic inhibition was derived using a diffusion model.

Results

At tissue concentrations of up to 75 microm (approximately 5 x predicted minimal alveolar concentration), F6 had no discernible effect on either the amplitude or the kinetics of GABA-mediated synaptic currents. Isoflurane, by contrast, prolonged the decay time constant of these currents at 100 microm (approximately 0.3 x minimal alveolar concentration).

Conclusions

At concentrations that bracket the in vivo amnestic and seizure-inducing range, F6 has no discernible effect on fast synaptic GABAA receptors in hippocampal CA1 pyramidal neurons. Synaptic GABAA receptors sharply discriminate between volatile anesthetics and a prototype nonimmobilizer. Similar in vivo effects of anesthetics and nonimmobilizers may be mediated by different cellular mechanisms.
Inhibitory Effect of Fentanyl on Acetylcholine-induced Relaxation in Rat Aorta
Authors: Sohn Ju-Tae , Ok Seong-Ho , Kim Hee-Jin , Moon Seon-Hak , Shin Il-Woo , Lee Heon-Keun , Chung Young-Kyun
Published: June 2004

Background

Previous study has shown that fentanyl attenuates acetylcholine-induced vasorelaxation. The goal of the current in vitro study was to identify the muscarinic receptor subtype that is mainly involved in the fentanyl-induced attenuation of endothelium-dependent relaxation elicited by acetylcholine.

Methods

The effects of fentanyl and muscarinic receptor antagonists on the acetylcholine concentration-response curve were assessed in aortic vascular smooth muscle ring preparations precontracted with phenylephrine. In the rings pretreated independently with pirenzepine, 4-diphenylacetoxyl-N-methylpiperidine methiodide, and naloxone, acetylcholine concentration-response curves were generated in the presence and absence of fentanyl. The effect of fentanyl on the concentration-response curve for calcium ionophore A23187 was assessed.

Results

Fentanyl (0.297 x 10 0.785 x 10 m) attenuated acetylcholine-induced vasorelaxation in ring preparations with or without 10 m naloxone. Pirenzepine (10 to 10 m) and 4-diphenylacetoxyl-N-methylpiperidine methiodide (10 to 10 m) produced a parallel rightward shift in the acetylcholine concentration-response curve. The concentrations (-log M) of pirenzepine and 4-diphenylacetoxyl-N-methylpiperidine methiodide necessary to displace the concentration-response curve of an acetylcholine by twofold were estimated to be 6.886 +/- 0.070 and 9.256 +/- 0.087, respectively. Methoctramine, 10 m, did not alter the acetylcholine concentration-response curve. Fentanyl, 0.785 x 10 m, attenuated acetylcholine-induced vasorelaxation in the rings pretreated with 10 m pirenzepine but had no effect on vasorelaxation in the rings pretreated with 10 m 4-diphenylacetoxyl-N-methylpiperidine methiodide. Fentanyl, 0.785 x 10 m, did not significantly alter calcium ionophore A23187-induced vasorelaxation.

Conclusions

These results indicate that fentanyl attenuates acetylcholine-induced vasorelaxation via an inhibitory effect at a level proximal to nitric oxide synthase activation on the pathway involving endothelial M3 muscarinic receptor activation in rat aorta.
Surfactant Reduction in Embolism Bubble Adhesion and Endothelial Damage
Authors: Suzuki Akira , Armstead Stephen C. , Eckmann David M.
Published: June 2004

Background

Surfactants may reduce the adhesion force holding bubbles to the vessel wall in gas embolism. The authors measured bubble adhesion force using excised microvessels. They assessed endothelial damage by measuring vessel reactivity and with microscopy.

Methods

Microbubbles injected into arterioles resided for 5, 10, or 30 min, with intact or damaged endothelium. Perfusion was with rat serum alone (control) or with 1% Perftoran (OJSC SPC Perftoran, Moscow, Russia) or 1% Pluronic F-127 (Molecular Probes, Eugene, OR) added. Pressure across the bubble, bubble length, and bubble diameter were measured, and adhesion force per unit surface area, K = deltaPD/4 l, was calculated. Vessel reactivity was assessed using topical application of phenylephrine and acetylcholine.

Results

With the endothelium intact, K was higher in controls than with Perftoran at 10 and 30 min or Pluronic F-127 at 10 min (P < 0.05). With surfactant added after air perfusion to damage the endothelium, K was lower (P < 0.05) at all times for both Perftoran and Pluronic F-127. With surfactant in the perfusate before air perfusion, K was lower at 10 and 30 min for Perftoran and at 10 min for Pluronic F-127 than for controls (P < 0.05). Phenylephrine-induced vasoconstriction was identical among groups. Acetylcholine-induced vasodilatation was the same among groups with an intact endothelium but was found to be lower in controls after air perfusion that followed surfactant exposure than in either surfactant group (P < 0.05).

Conclusions

Surfactants reduced bubble adhesion force and preserved basic endothelial structure and vasodilatory function despite attempts to damage the endothelium. Surfactants seem to protect the endothelium from mechanically induced injury in addition to decreasing bubble adhesion forces.
An In Vivo Evaluation of the Mycobacterial Filtration Efficacy of Three Breathing Filters Used in Anesthesia
Authors: Vezina Daniel P. , Trépanier Claude A. , Lessard Martin R. , Gourdeau Marie , Tremblay Claude , Guidoin Robert
Published: June 2004

Background

The use of breathing filters (BFs) has been recommended to protect the anesthesia apparatus in proven or suspected cases of tuberculosis. Some investigators have also suggested the use of BF to alleviate the need to change anesthesia breathing circuits after each case. This study evaluated the filtration efficacy of three different BFs to prevent mycobacterial contamination of breathing circuits in a model that uses a test animal.

Methods

Ten Pall BB25A (pleated hydrophobic) (Pall Canada Ltd., Mississauga, Ontario, Canada), six DAR Barrierbac S (felted electrostatic; Mallinckrodt DAR, Mirandola, Italy), and six Baxter Airlife (felted electrostatic; Baxter Canada, Mississauga, Ontario, Canada) BFs were studied. For each BF tested, 20 ml of a high concentration suspension of Mycobacterium chelonae (range, 2.0 x 10 to 9.0 x 10 colony-forming units/ml) was nebulized during 2 h at the proximal end of the endotracheal tube of anesthetized pigs. At the end of the nebulization period, the BFs were sampled for culture. The titer reduction value (number of microorganisms challenging the BF divided by the number of microorganisms recovered downstream of the BF) and the removal efficiency (difference between the number of microorganisms challenging the BF and the number of microorganisms recovered downstream of the BF, divided by the number of microorganisms challenging the BF) were calculated.

Results

The median titer reduction values were 5.6 x 10, 6.0 x 10, and 8.0 x 10 (P < 0.0005), and the median removal efficiencies were greater than 99.999%, greater than 99.999%, and 100% (P = not significant) for the DAR Barrierbac S, the Baxter Airlife, and the Pall BB25A, respectively.

Conclusions

Among the three BFs studied, only the Pall BB25A completely prevented the passage of M. chelonae, thus protecting the anesthesia breathing circuit from mycobacterial contamination.
Lidocaine Increases Intracellular Sodium Concentration through Voltage-dependent Sodium Channels in an Identified Lymnaea Neuron
Authors: Onizuka Shin , Kasaba Toshiharu , Hamakawa Toshiro , Ibusuki Shoichiro , Takasaki Mayumi
Published: June 2004

Background

The local anesthetic lidocaine affects neuronal excitability in the central nervous system; however, the mechanisms of such action remain unclear. The intracellular sodium concentration ([Na]i) and sodium currents (INa) are related to membrane potential and excitability. Using an identifiable respiratory pacemaker neuron from Lymnaea stagnalis, the authors sought to determine whether lidocaine changes [Na]i and membrane potential and whether INa is related to these changes.

Methods

Intracellular recording and sodium imaging were used simultaneously to measure membrane potentials and [Na]i, respectively. Measurements for [Na]i were made in normal, high-Na, and Na-free salines, with membrane hyperpolarization, and with tetrodotoxin pretreatment trials. Furthermore, changes of INa were measured by whole cell patch clamp configuration.

Results

Lidocaine increased [Na]i in a dose-dependent manner concurrent with a depolarization of the membrane potential. In the presence of high-Na saline, [Na]i increased and the membrane potential was depolarized; the addition of lidocaine further increased [Na]i, and the membrane potential was further depolarized. In Na-free saline or in the presence of tetrodotoxin, lidocaine did not change [Na]i. Similarly, hyperpolarization of the membrane by current injections also prevented the lidocaine-induced increase of [Na]i. In the patch clamp configuration, membrane depolarization by lidocaine led to an inward sodium influx. A persistent reduction in membrane potential, resulting from lidocaine, brings the cell within the window current of INa where sodium channel activation occurs.

Conclusion

Lidocaine increases intracellular sodium concentration and promotes excitation through voltage-dependent sodium channels by altering membrane potential in the respiratory pacemaker neuron.
A Comparison of Infraclavicular Nerve Block versus General Anesthesia for Hand and Wrist Day-case Surgeries
Authors: Hadzic Admir , Arliss Jeffrey , Kerimoglu Beklen , Karaca Pelin Emine , Yufa Marina , Claudio Richard E. , Vloka Jerry D. , Rosenquist Richard , Santos Alan C. , Thys Daniel M.
Published: June 2004

Background

General anesthesia (GA) and brachial plexus block have been used successfully for surgery on the upper extremities. Controversy exists as to which method is more suitable in outpatients undergoing hand and wrist surgery. The authors hypothesized that infraclavicular brachial plexus block (INB) performed with a short-acting local anesthetic would result in shorter time to discharge home as compared with "fast-track" GA.

Methods

After obtaining written informed consent, 52 patients (aged 18-65 yr, American Society of Anesthesiologists physical status I-III) were randomly assigned to receive either an INB or GA under standardized protocols (INB = 3% 2-chloroprocaine + HCO3 + epinephrine 1:300000, followed by propofol sedation; GA = 12.5 mg dolasetron, propofol induction, followed by laryngeal mask airway insertion and desflurane for maintenance; 0.25% bupivacaine for wound infiltration). At the conclusion of the procedure, nurses blinded to the study goals and the anesthetic technique used a modified Aldrete score to decide whether patients could bypass the postanesthesia care unit. Additional data were collected regarding time to postoperative pain, ambulation, home readiness, and incidence of adverse events.

Results

More patients in the INB group (79%) met the criteria to bypass the postanesthesia care unit compared with patients in the GA group (25%; P < 0.001). Compared with patients in the GA group, fewer patients in the INB group had pain (visual analog scale score > 3) on arrival to the postanesthesia care unit (3% vs. 43%; P < 0.001). None of the patients in the INB group requested treatment for pain while in the hospital, compared with 48% of patients in the GA group (P < 0.001). Patients in the INB group were able to ambulate earlier (82 +/- 41 min) compared with those in the GA group (145 +/- 70 min; P < 0.001). Time to home readiness and discharge times were shorter for patients in the INB group (100 +/- 44 and 121 +/- 37 min) compared with those in the GA group (203 +/- 91 and 218 +/- 93 min; P < 0.001). Adverse events (e.g., nausea, vomiting, sore throat) occurred less frequently in patients undergoing INB as compared with those undergoing GA.

Conclusion

Infraclavicular brachial plexus block with a short-acting local anesthetic was associated with time-efficient anesthesia, faster recovery, fewer adverse events, better analgesia, and greater patient acceptance than GA followed by wound infiltration with a local anesthetic in outpatients undergoing hand and wrist surgery.
Sciatic Nerve Block via Posterior Labat Approach Is More Efficient Than Lateral Popliteal Approach Using a Double-injection Technique
Authors: Taboada Manuel , Rodríguez Jaime , Álvarez Julián , Cortés Joaquín , Gude Francisco , Atanassoff Peter G.
Published: June 2004

Background

For peripheral nerve blockade, the double-injection technique proved to be superior to a single injection in previous investigations. The current study was designed to compare onset time and efficacy of two different double-injection approaches for sciatic nerve block with 0.75% ropivacaine.

Methods

A total of 50 patients undergoing foot surgery were randomly assigned to receive sciatic nerve blockade by means of the classic (Labat) posterior approach (n = 25) or a lateral popliteal approach (n = 25). All blocks were performed with the use of a nerve stimulator, and both major components of the sciatic nerve (tibial and common peroneal nerves) received separately 10 ml ropivacaine, 0.75%. Success rate was defined as a complete sensory and motor block associated with pain-free surgery.

Results

A greater success rate was observed in the classic group (96%) as compared with the popliteal group (68%; P < 0.05). A general anesthetic became necessary in six patients (24%) with the lateral popliteal approach and none with the classic approach (P < 0.05). The onset of complete sensory and motor blockade was significantly faster in the classic group (12 +/- 6 min) as compared with the popliteal group (26 +/- 10 min; P < 0.05).

Conclusion

A double injection with a relatively low volume of 0.75% ropivacaine generated a higher success rate and a shorter onset time of sensory and motor blockade after the classic Labat approach than after a lateral popliteal approach.
Effects of Perioperative Central Neuraxial Analgesia on Outcome after Coronary Artery Bypass Surgery
Authors: Liu Spencer S. , Block Brian M. , Wu Christopher L.
Published: June 2004

Background

Perioperative central neuraxial analgesia may improve outcome after coronary artery bypass surgery due to attenuation of stress response and superior analgesia.

Methods

MEDLINE and other databases were searched for randomized controlled trials in patients undergoing coronary artery bypass surgery with cardiopulmonary bypass who were randomized to either general anesthesia (GA) versus general anesthesia-thoracic epidural analgesia (TEA) or general anesthesia-intrathecal analgesia (IT).

Results

Fifteen trials enrolling 1178 patients were included for TEA analysis. TEA did not affect incidences of mortality (0.7% TEA vs. 0.3% GA) or myocardial infarction (2.3% TEA vs. 3.4% GA). TEA significantly reduced the risk of dysrhythmias with an odds ratio of 0.52, pulmonary complications with an odds ratio of 0.41, and time to tracheal extubation by 4.5 h and reduced analog pain scores at rest by 7.8 mm and with activity by 11.6 mm. Seventeen trials enrolling 668 patients were included for IT analysis. IT had no significant effect on incidences of mortality (0.3% IT vs. 0.6% GA), myocardial infarction (3.9% IT vs. 5.7% GA), dysrhythmias (24.8% vs. 29.1%), nausea/vomiting (31.3% vs. 28.5%), or time to tracheal extubation (10.4 h IT vs. 10.9 h GA). IT modestly decreased systemic morphine use by 11 mg and decreased pain scores by 16 mm. IT significantly increased the incidence of pruritus (10% vs. 2.5%).

Conclusions

There were no differences in the rates of mortality or myocardial infarction after coronary artery bypass grafting with central neuraxial analgesia. There were associated improvements in faster time until tracheal extubation, decreased pulmonary complications and cardiac dysrhythmias, and reduced pain scores.
Preventive Analgesia Is Associated with Reduced Pain Disability 3 Weeks but Not 6 Months after Major Gynecologic Surgery by Laparotomy
Authors: Katz Joel , Cohen Lorenzo
Published: June 2004

Background

Most studies of preemptive or preventive analgesia restrict outcomes to pain and analgesic consumption in the acute postoperative period. The potential longer-term effects on these and other domains of functioning have received little empirical attention. The purpose of this study was to follow up patients who had received general anesthesia plus epidural fentanyl and lidocaine before (group 1) or after (group 2) incision or general anesthesia plus a sham epidural (group 3).

Methods

Patients were contacted approximately 3 weeks and 6 months after surgery. A follow-up pain questionnaire and the McGill Pain Questionnaire were administered by telephone. The Mental Health Inventory and Pain Disability Index were mailed to patients, completed, and mailed back.

Results

One hundred thirty-one of the 141 patients (93%) were reached 3 weeks after surgery (n = 41, n = 48, and n = 42 in groups 1, 2, and 3, respectively), and 109 (77%) were reached at 6 months (n = 35, n = 37, and n = 37 in groups 1, 2, and 3, respectively). Multivariate analysis of covariance indicated that that even after controlling for age and presence or absence of preoperative pain, Pain Disability Index scores (mean +/- SD) at the first follow-up were significantly lower in group 1 (17.3 +/-12.8) and group 2 (18.1 +/-17.0) compared with group 3 (26.3 +/- 18.3). McGill Pain Questionnaire and Mental Health Inventory scores did not differ significantly among the groups. There were no significant differences at the 6-month follow-up.

Conclusion

The short-term beneficial effects of preventive epidural analgesia translated into less pain disability 3 weeks after surgery. Progress in understanding the processes involved in postsurgical recovery and the risk factors for chronic postsurgical pain would be aided by baseline and postsurgical measures of relevant psychological, emotional, and physical variables.
Quality of Postoperative Pain Using an Intraoperatively Placed Epidural Catheter after Major Lumbar Spinal Surgery
Authors: Gottschalk André , Freitag Marc , Tank Sascha , Burmeister Marc-Alexander , Kreißl Sonja , Kothe Ralph , Hansen-Algenstedt Nils , Weisner Lothar , Staude Hans-Jürgen , Standl Thomas
Published: June 2004

Background

Major spinal surgery is associated with high postoperative pain scores and opioid requirement. The aim of the current prospective, randomized, placebo-controlled, double-blind study was to assess the reduction of opioid requirement and pain scores using an intraoperatively placed epidural catheter with infusion of 0.1% ropivacaine during the postoperative period.

Methods

Thirty patients undergoing major lumbar spinal surgery from a dorsal approach were included in this study. Before wound closure, the orthopedic surgeon inserted an epidural catheter. Postoperatively, patients were randomly assigned to receive an infusion of 12 ml/h ropivacaine, 0.1% (group R), or 12 ml/h saline (group N) after an initial bolus of 10 ml of the respective study solution. Additional pain relief was provided using an intravenous patient-controlled analgesia pump with the opioid piritramide. Patients were assessed with respect to pain scores (visual analog scale of 0-100), cumulative opioid requirement, side effects, and satisfaction with pain management.

Results

: Demographic data, duration of surgery, and type of surgery were comparable between groups. Pain scores were assessed as follows (group R vs. group N: 6 h: 24 +/-20 vs. 51 +/- 20, P = 0.002; 24 h: 33 +/- 19 vs. 53 +/- 27, P = 0.04; 48 h: 21 +/-17 vs. 40 +/- 26, P = 0.04; 72 h: 14 +/- 13 vs. 38 +/- 25, P = 0.02). The cumulative piritramide requirement after 72 h was 97 +/- 23 mg in group R and 157 +/-72 mg in group N (P = 0.03). The incidence of side effects was comparable between groups, and patient satisfaction was always higher in group R (P < 0.05).

Conclusion

Continuous epidural infusion of 0.1% ropivacaine results in lower pain scores and opioid consumption and higher patient satisfaction when compared with placebo. Application of ropivacaine using an epidural catheter seems to be a highly effective treatment for postoperative pain after major lumbar spinal surgery.
α2AAdrenoceptors Contribute to Feedback Inhibition of Capsaicin-induced Hyperalgesia
Authors: Mansikka Heikki , Lähdesmäki Janne , Scheinin Mika , Pertovaara Antti
Published: June 2004

Background

Studies on receptor knockout mice have so far shown that of the three alpha2-adrenoceptor subtypes, the alpha(2A) adrenoceptor has a major role in mediating the powerful central analgesia induced by synthetic alpha2-adrenoceptor agonists. However, because a knockout of the gene for the alpha(2A) adrenoceptor has produced only little if any change in the pain sensitivity of control, nerve-injured, or inflamed animals, it has not been clear whether activation of alpha(2A)-adrenoceptors by endogenous ligands has a significant pain regulatory role.

Methods

The authors assessed spontaneous pain behavior and mechanical hypersensitivity induced by administration of capsaicin in the colon or paw of alpha(2A)-adrenoceptor knockout mice versus their wild-type controls.

Results

Enhanced pain hypersensitivity was observed in alpha(2A)-adrenoceptor knockout mice 20 min or more after administration of capsaicin, but before, hypersensitivity and spontaneous pain were of equal magnitude in alpha(2A)-adrenoceptor knockout and wild-type mice. When wild-type mice were pretreated with an alpha2-adrenoceptor antagonist, capsaicin-induced pain hypersensitivity increased to a level equal to that in alpha(2A)-adrenoceptor knockout mice. Capsaicin-induced hypersensitivity was suppressed in wild-type but not alpha(2A)-adrenoceptor knockout mice by a centrally acting alpha2-adrenoceptor agonist, whereas a peripherally acting alpha2-adrenoceptor agonist was without effect on hypersensitivity, although it attenuated capsaicin-induced spontaneous pain behavior in wild-type mice.

Conclusions

This study shows that central alpha(2A)-adrenoceptors contribute to feedback inhibition of pain hypersensitivity. Also, alpha(2A)-adrenoceptors are critical for not only somatic but also visceral antinociceptive effects induced by synthetic alpha2-adrenoceptor agonists.
Effects of Laparotomy on Spontaneous Exploratory Activity and Conditioned Operant Responding in the Rat
Authors: Martin Thomas J. , Buechler Nancy L. , Kahn William , Crews James C. , Eisenach James C.
Published: June 2004

Background

Treatment of postsurgical pain is a major use of analgesics, particularly after abdominal surgery. Analgesics display a number of limiting side effects, including sedation, cognitive impairment, and ileus. Although several postoperative rodent models have been developed, these models do not address these concerns.

Methods

A model is presented in the rat in which a subcostal incision is performed, penetrating into the peritoneal cavity. The behavioral effects of this surgical procedure are assessed using exploratory locomotor activity and conditioned operant responding. The effects of morphine and ketorolac were assessed in both behavioral paradigms.

Results

Laparotomy decreased ambulation and rearing by approximately 50% 24 h after surgery, and stereotypy (small confined movements) was affected to a lesser degree. The effects of laparotomy on conditioned operant responding were more complex. Total number of sucrose pellets earned was decreased for 2-3 days after laparotomy; however, the amount of time required was increased for up to 2 weeks. Morphine reversed the effects of surgery on ambulation and stereotypy but not rearing, and the dose-effect curve for morphine was shifted to the left by 5 mg/kg ketorolac. Ketorolac produced significant improvement in operant responding after laparotomy, and coadministration of ineffective doses of morphine and ketorolac produced a positive response.

Conclusion

The current model is consistent with behavioral aspects of postoperative pain seen clinically. The effects of morphine and ketorolac alone and in combination were consistent with the reported analgesic efficacy and occurrence of side effects found with these agents clinically.
Seeing the Light
Authors: Franks Nicholas P. , Lieb William R. , Raja Srinivasa N.
Published: June 2004

Most proteins are insensitive to the presence of general anaesthetics at concentrations which induce anaesthesia, while some are inhibited by some agents but not others. Here we show that, over a 100000-fold range of potencies, the activity of a pure soluble protein (firefly luciferase) can be inhibited by 50% at anaesthetic concentrations which are essentially identical to those which anaesthetize animals. This identity holds for inhalational agents (such as halothane, methoxyflurane and chloroform), aliphatic and aromatic alcohols, ketones, ethers and alkanes. This finding is all the more striking in view of the fact that the inhibition is shown to be competitive in nature, with anaesthetic molecules competing with the substrate (luciferin) molecules for binding to the protein. We show that the anaesthetic-binding site can accommodate only one large, but more than one small, anaesthetic molecule. The obvious mechanism suggested by our results is that general anaesthetics, despite their chemical and structural diversity, act by competing with endogenous ligands for binding to specific receptors.
Impaired Neurovascular Coupling by Transhemispheric Diaschisis in Rat Cerebral Cortex
Authors: Enager Pia , Gold Lorenz , Lauritzen Martin
Published: June 2004

In acute brain disorders, elimination of the excitatory output from an injured brain region reduces activity in connecting brain regions remote from the lesion site (i.e., diaschisis). The authors examined the effect of functional ablation of the left cerebral cortex by cortical spreading depression (CSD) or topical application of tetrodotoxin on single cell spiking activity, baseline CBF, and neurovascular coupling in the right rat sensory cortex. CSD or tetrodotoxin in left cortex reduced the right cortical spontaneous spike rate by 36% and 45%, respectively. Baseline CBF in the right cortex was unaffected by a left-sided CSD, but decreased by 12% for left cortical application of tetrodotoxin. This suggested dissociation between spontaneous spiking activity and basal CBF. Left infraorbital nerve stimulation evoked local field potentials in right cerebral cortex that were reduced in amplitude by 19% for left CSD and by 23% for left tetrodotoxin application. The corresponding declines in the evoked CBF responses were 42% for CSD and 23% for tetrodotoxin. Vascular reactivity to adenosine remained unchanged in right cortex. Thus, transhemispheric diaschisis produced a pronounced decrease in the spontaneous spike rate accompanied by no reduction or a small reduction in basal CBF, and an attenuation in amplitudes of evoked synaptic responses and corresponding rises in CBF. The findings suggest that disturbed neurovascular coupling may contribute to the disturbance in brain function in acute transhemispheric diaschisis.
Induction of Caspase-Mediated Cell Death by Matrix Metalloproteinases in Cerebral Endothelial Cells after Hypoxia—Reoxygenation
Authors: Lee Sun-Ryung , Lo Eng H.
Published: June 2004

Matrix metalloproteinases (MMPs) may contribute to the pathophysiology of cerebral ischemia by degrading matrix components in the neurovascular unit. In this study, the authors document a pathway by which MMPs interfere with cell—matrix interactions and trigger caspase-mediated cytotoxicity in brain endothelial cells. Hypoxia—reoxygenation induced endothelial cytotoxicity. Cytoprotection with zDEVD-fmk confirmed that cell death was partly caspase mediated. The temporal profile of caspase-3 activation was matched by elevations in MMP-2 and MMP-9. MMP inhibitors significantly decreased caspase-3 activation and reduced endothelial cell death. Degradation of matrix fibronectin confirmed the presence of extracellular proteolysis. Increasing integrin-linked kinase signaling with the β1 integrin-activating antibody (8A2) ameliorated endothelial cytotoxicity. The results suggest that MMP-9 and MMP-2 contribute to caspase-mediated brain endothelial cell death after hypoxia—reoxygenation by disrupting cell—matrix interactions and homeostatic integrin signaling.
Characterization of a Novel Chronic Photothrombotic Ring Stroke Model in Rats by Magnetic Resonance Imaging, Biochemical Imaging, and Histology
Authors: Hilger Thomas , Blunk James A. , Hoehn Mathias , Mies Günter , Wester Per
Published: June 2004

A novel photothrombotic ring stroke model was characterized by multiparametric magnetic resonance imaging, imaging of cerebral blood flow (CBF), adenosine triphosphate (ATP), pH, and histology. Ischemia was initiated by transosseous irradiation of a predefined brain area intravenously perfused by the photosensitive dye erythrosin B in male Wistar rats. In the region of the primary ring-lesion, the phototoxic reaction caused necrosis reflected by low relative ATP levels (28 ± 15%), alkalosis (pH: 7.35 ± 0.50), and histologic evidence at 14 days after lesion induction. In the ring-encircled interior region (region-at-risk), spontaneous tissue reperfusion (relative CBF: 93 ± 3%) enabled partial tissue preservation. This was demonstrated by a less impaired energy metabolism (ATP: 65 ± 23%), normal pH (7.01 ± 0.50), and still normal cellular structures shown by histologic staining. Analysis of the temporal characteristics within the region-at-risk revealed a slow continuous increase of the apparent diffusion coefficient of water (ADC) to 144 ± 16% of control (14d) and an early vasogenic edema, reflected by an increase of the T2 relaxation time to 143 ± 17% of control (2d). Both final ADC and T2 correlated well with the tissue pH within the region-at-risk, thus emphasizing the usefulness of this multiparametric noninvasive imaging approach.
Neural Stem Cells in the Subventricular Zone are Resilient to Hypoxia/Ischemia whereas Progenitors are Vulnerable
Authors: Romanko Michael J. , Rothstein Raymond P. , Levison Steven W.
Published: June 2004

Perinatal hypoxic-ischemic (H/I) brain injury remains a major cause of neurologic disability. Because we have previously demonstrated that this insult depletes cells from the subventricular zone (SVZ), the goal of the present investigation was to compare the relative vulnerability to H/I of neural stem cells versus progenitors. The dorsolateral SVZs of P6 rats were examined at 2 to 48 hours of recovery from H/I using hematoxylin and eosin, in situ end labeling (ISEL), terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate-biotin nick end labeling (TUNEL), electron microscopy, and immunofluorescence. Pyknotic nuclei and ISEL+ cells were observed by 4 hours of recovery, peaked at 12 hours, and persisted for at least 48 hours. Many active-caspase3+ cells were observed at 12 hours and they comprised one third of the total TUNEL+ population. Electron microscopy revealed that hybrid cell deaths predominated at 12 hours of recovery. Importantly, few dying cells were observed in the medial SVZ, where putative stem cells reside, and no nestin+ medial SVZ cells showed caspase-3 activation. By contrast, active-caspase-3+/PSA-NCAM+ progenitors were prominent in the lateral SVZ. These data demonstrate that early progenitors are vulnerable to H/I, whereas neural stem cells are resilient. The demise of these early progenitors may lead to the depletion of neuronal and late oligodendrocyte progenitors, contributing to cerebral dysgenesis after perinatal insults.
Progesterone Enhances Functional Recovery after Middle Cerebral Artery Occlusion in Male Mice
Authors: Gibson Claire L. , Murphy Sean P.
Published: June 2004

Sex differences have been observed in the outcome after ischemia that are believed to be attributable to sex steroid hormones. The present study investigated the possible benefits of progesterone administration after focal cerebral ischemia. Male mice underwent 60-minute middle cerebral artery occlusion (MCAO) and received progesterone (8 mg/kg, intraperitoneally) or vehicle (dimethyl sulfoxide) 1, 6, and 24 hours after MCAO. The lesion volume at 48 hours after MCAO was significantly reduced ( P < 0.05) in progesterone-treated mice compared with vehicle-treated mice. All other mice underwent tests of well being (survival rate and body weight recovery), motor ability (grid test and rotarod), and cognitive ability (water maze) for up to 21 days. MCAO significantly worsened outcome in all of these tests compared with shams. Progesterone treatment was beneficial in that compared with vehicle, it significantly improved survival rate, weight recovery, and motor ability. This improvement was most apparent during water maze testing, where progesterone-treated mice were indistinguishable from shams in terms of acquiring the task. These results indicate beneficial effects of progesterone administration after cerebral ischemia and illustrate the need to further investigate the mechanisms of progesterone action.
The Upregulation of Cognate and Inducible Heat Shock Proteins in the Anoxic Turtle Brain
Authors: Prentice Howard M. , Milton Sarah L. , Scheurle Daniela , Lutz Peter L.
Published: June 2004

Because heat shock proteins (HSPs) have an important protective function against ischemia/anoxia in mammalian brain, the authors investigated the expression of Hsp72 and Hsc73 in the anoxia-surviving turtle brain. Unlike the mammalian brain, high levels of Hsp72 were found in the normoxic turtle brain. Hsp72 levels were significantly increased by 4 hours of anoxia, remained constant until 8 hours, and then decreased to baseline at 12 hours. By contrast, Hsc73 was progressively increased throughout 12 hours of anoxia. This differential expression suggests different protective roles: Hsp72 in the initial downregulatory transition phase, and Hsc73 in maintaining neural network integrity during the long-term hypometabolic phase.
Use of the census of population to discern trends in the Welsh language: an aggregate analysis
Authors: Higgs Gary , Williams Colin , Dorling Danny
Published: June 2004

The aim of this paper is to present a preliminary analysis of unitary authority level data from the 2001 census of population on the spatial (and, where available, temporal) patterns in proportions of Welsh speakers in Wales. In so doing we draw attention to the advantages (and limitations) of the census as a source of information on the state of the Welsh language. Although a 2 per cent increase in the percentage of Welsh speakers between 1991 and 2001 has been welcomed, several commentators have drawn attention to the change in the nature of the question asked at the 2001 census which may account for some of this increase. In this paper, we assess what is, and is not, possible to discern from the census, draw attention to other potential sources of information on the language and make some preliminary recommendations for those agencies concerned with monitoring trends in the future, both with regard to the need for more detailed language use surveys and the nature of the question included in subsequent censuses that would permit a more useful comparison of spatial and temporal trends.
Have we learned to count yet? A health services perspective on the 2001 census
Authors: Hennell Tom
Published: June 2004

English health services require reliable population denominators to guide equitable sharing of resources. 2001 census counts for England are compared with the corresponding 2000‐base projections for 2001, both at the national scale and for individual local authorities and also with corresponding 1996‐base projections. Comparison is made with the 2001 census for Northern Ireland. National patterns of variation predominantly may be explained by mis‐estimation of international out‐migration, but local patterns of variation may be more specifically related to mis‐estimation of international in‐migration. This suggests two distinct patterns of systematic error in official UK migration statistics between 1991 and 2001.
Housing Demand, Coping Strategy, and Selection Bias
Authors: MIRON JOHN R.
Published: June 2004

ABSTRACT  In conventional modeling of housing demand, consumers choose living arrangement, tenure, and housing on the basis of price, income, wealth, and tastes. However, it is both costly and onerous to alter one's housing conditions. It is argued therefore that consumers employ housing strategies to cope with labor market risks and expectations about their future: strategies that may differ from one demographic group to the next. In conventional modeling of housing demand, it is also well‐known that selection bias can arise: that is, omitted variables that help account for one aspect of housing (say, tenure choice) also subsequently affect the nature of the demand function for other aspects of housing demand (say, the amount spent on housing by a renter household). One such variable is the consumer's wealth, a variable that is typically not available in household survey data. This paper argues that the most important variables that may give rise to selection bias are variables that also reflect the coping strategies employed by consumers. The paper estimates a model of housing choice using Canada‐wide pooled samples from the 1980s and 1990s. In this paper, the prices of housing services and income prospects vary region by region. The paper shows how individuals and families in different housing markets across Canada respond, and how this evidences the use of coping strategies (from doubling up to substandard housing). The paper presents evidence to support the argument that selection bias is important in understanding how consumers cope.
Social and organisational implications of CAD usage: a grounded theory in a fashion company
Authors: Bertolotti Fabiola , Macrì Diego Maria , Tagliaventi Maria Rita
Published: June 2004

This paper focuses on the process of Computer Aided Design (CAD) diffusion into a group engaged in the development of innovative products. Adopting an ethnographic approach, we build a grounded theory for interpreting CAD usage in terms of the interplay between variables such as management orientation, training, actors’ specialisation and deskilling, availability of shared archives, technological discontinuities between organisational areas.
The limited acceptance of an electronic prescription system by general practitioners: reasons and practical implications
Authors: Boonstra Albert , Boddy David , Fischbacher Moira
Published: June 2004

To control the cost of drugs prescribed by general practitioners (GPs), the Netherlands Ministry of Health decided to implement an electronic prescription system. This paper uses an interpretive perspective to analyse the reasons for limited acceptance of the system. While the promotion campaign focused on the system, GPs based their decision on wider contextual factors.