bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.