bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibitory Effects of Barbiturates on Nicotinic Acetylcholine Receptors in Rat Central Nervous System Neurons
Authors: Kamiya Yoshinori , Andoh Tomio , Watanabe Itaru , Higashi Tomoko , Itoh Hideki 
Published: November 2003

Background
Neuronal nicotinic acetylcholine receptors (nAChRs) are widely expressed in the central and autonomic nervous systems. The authors have previously shown that depressant and convulsant barbiturates both inhibit the ganglion-type nAchRs in PC12 cells. However, the central and gangliontype receptors have different subunit composition and pharmacologic properties. In this study, the authors investigated the effects of thiopental, depressant [R(-)] and convulsant [S(+)] stereoisomers of 1-methyl-5 phenyl-5-propyl barbituric acid (MPPB) on neuronal nAChRs in the rat central nervous system to explore significance of these effects in barbiturate anesthesia.

Methods
Whole-cell currents were measured in acutely dissociated rat medial habenula (MHb) neurons by applying 10 or 100 microM nicotine in the absence or presence of thiopental 3-100 microM. Effects of R(-)- and S(+)-MPPB on the nicotine-induced current were also studied.

Results
Thiopental suppressed the nicotine-elicited inward current and accelerated the current decay dose-dependently at the clinical relevant concentrations. R(-)- and S(+)-MPPB both inhibited the nicotine-induced current dose-dependently without augmenting the current decay. There was no significant difference in the magnitudes of inhibition by R(-)- and S(+)-MPPB.

Conclusions
Although thiopental suppressed the current mediated through native nAchRs in rat MHb neurons at the clinically relevant concentrations, the depressant and convulsant stereoisomers of MPPB both inhibited the current in the same extent. These findings are consistent with the results previously obtained in the ganglion-type receptors of PC12 cells and suggest that inhibition of nAChRs in MHb neurons is not directly relevant to the hypnotic or anticonvulsive actions of barbiturates.
Dose-dependent Regional Cerebral Blood Flow Changes during Remifentanil Infusion in Humans
Authors: Wagner Klaus J. , Willoch Frode , Kochs Eberhard F. , Siessmeier Thomas , Tölle Thomas R. , Schwaiger Markus , Bartenstein Peter 
Published: November 2003

Background
The current study investigated dose-dependent effects of the mu-selective agonist remifentanil on regional cerebral blood flow (rCBF) in volunteers using positron emission tomography (PET).

Methods
Ten right-handed male volunteers were included in a 15O-water PET study. Seven underwent three conditions: control (saline), low remifentanil (0.05 microg x kg(-1) x min(-1)), and moderate remifentanil (0.15 microg x kg(-1) x min(-1)). The remaining three participated in the low and moderate conditions. A semirandomized study protocol was used with control and remifentanil conditions 3 or more months apart. The order of low and moderate conditions was randomized. Cardiovascular and respiratory parameters were monitored. Categoric comparisons between the control, low, and moderate conditions and a pixelwise correlation analysis across the three conditions were performed (P < 0.05, corrected for multiple comparisons) using statistical parametric mapping.

Results
Cardiorespiratory parameters were maintained constant over time. At the low remifentanil dose, significant increases in relative rCBF were noted in the lateral prefrontal cortices, inferior parietal cortices, and supplementary motor area. Relative rCBF decreases were observed in the basal mediofrontal cortex, cerebellum, superior temporal lobe, and midbrain gray matter. Moderate doses further increased rCBF in mediofrontal and anterior cingulate cortices, occipital lobe transition, and caudal periventricular grey. Significant decreases were detected in the inferior parietal lobes. These dose-dependent effects of remifentanil on rCBF were confirmed by a correlation analysis.

Conclusion
Remifentanil induced dose-dependent changes in relative rCBF in areas involved in pain processing. At moderate doses, rCBF responses were additionally detected in structures known to participate in modulation of vigilance and alertness. Insight into the mechanisms of opioid analgesia within the pain-processing neural network may lead to a better understanding of antinociception and opioid treatment.
Dose–Response Relationship and Infusion Requirement of Cisatracurium Besylate in Infants and Children during Nitrous Oxide–Narcotic Anesthesia
Authors: de Ruiter Joost , Crawford Mark W. 
Published: November 2003

Background
To determine the effect of age on the dose-response relation and infusion requirement of cisatracurium besylate in pediatric patients, 32 infants (mean age, 0.7 yr; range, 0.3-1.0 yr) and 32 children (mean age, 4.9 yr; range, 3.1-9.6 yr) were studied during thiopentone-nitrous oxideoxygen-narcotic anesthesia.

Methods
Potency was determined using a single-dose (20, 26, 33, or 40 microg/kg) technique. Neuromuscular block was assessed by monitoring the electromyographic response of the adductor pollicis to supramaximal train-of-four stimulation of the ulnar nerve at 2 Hz.

Results
Least-squares linear regression analysis of the log-probit transformation of dose and maximal response yielded median effective dose (ED50) and 95% effective dose (ED95) values for infants (29+/-3 microg/kg and 43+/-9 microg/kg, respectively) that were similar to those for children (29+/-2 microg/kg and 47+/-7 microg/kg, respectively). The mean infusion rate necessary to maintain 90-99% neuromuscular block during the first hour in infants (1.9+/-0.4 microg x kg(-1) x min(-1); range: 1.3-2.5 microg x kg(-1) x min(-1)) was similar to that in children (2.0+/-0.5 microg x kg(-1) x min(-1); range: 1.3-2.9 microg x kg(-1) x min(-1)).

Conclusion
The authors conclude that cisatracurium is equipotent in infants and children when dose is referenced to body weight during balanced anesthesia.
Epinephrine Increases the Neurotoxic Potential of Intrathecally Administered Lidocaine in the Rat
Authors: Hashimoto Keishi , Hampl Karl F. , Nakamura Yuji , Bollen Andrew W. , Feiner John , Drasner Kenneth 
Published: November 2003

Background
Epinephrine is commonly added to lidocaine solutions to increase the duration of spinal anesthesia. Despite this common usage, the effect of epinephrine on the neurotoxic potential of this anesthetic is not known. The current experiments investigated whether adding epinephrine increases functional impairment or histologic damage induced by spinal administration of lidocaine in the rat.

Methods
Eighty rats were divided into four groups to receive an intrathecal injection of normal saline containing either 5% lidocaine, 5% lidocaine with 0.2 mg/ml of epinephrine, 0.2 mg/ml of epinephrine, or normal saline alone. Animals were assessed for persistent sensory impairment using the tail-flick test administered 4 and 7 days after infusion. Animals were then killed, and the spinal cord and nerve roots were prepared for neuropathologic evaluation.

Results
Rats given 5% lidocaine developed persistent sensory impairment and histologic damage, and the addition of epinephrine resulted in a further significant increase in injury. Sensory function in animals given epinephrine without anesthetic was similar to baseline and did not differ from saline. Histologic changes in animals treated with epinephrine alone did not differ significantly from saline controls.

Conclusions
The neurotoxicity of intrathecally administered lidocaine is increased by the addition of epinephrine. When making clinical recommendations for maximum safe intrathecal dose of this anesthetic, one may need to consider whether the solution contains epinephrine.
Propofol Alters the Pharmacokinetics of Alfentanil in Healthy Male Volunteers
Authors: Mertens Martijn J. , Vuyk Jaap , Olofsen Erik , Bovill James G. , Burm Anton G. L. 
Published: November 2003

Background
The influence of propofol on the pharmacokinetics of alfentanil is poorly understood. The authors therefore studied the effect of a pseudo-steady state concentration of propofol on the pharmacokinetics of alfentanil.

Methods
The pharmacokinetics of alfentanil was studied on two occasions in eight male volunteers in a randomized crossover manner with a 3-week interval. While breathing 30% O2 in air, 12.5 microg/kg intravenous alfentanil was given in 2 min, followed by 25 microg.kg(-1).h(-1) for 58 min (sessions A and B). During session B, a target controlled infusion of propofol (target concentration, 1.5 microg/ml) was given from 10 min before the start until 6 h after termination of the alfentanil infusion. Blood pressure, cardiac output, electrocardiogram, respiratory rate, oxygen saturation, and end-tidal carbon dioxide were monitored. Venous blood samples for determination of the plasma alfentanil concentration were collected until 6 h after termination of the alfentanil infusion. Nonlinear mixed-effects population pharmacokinetic models examining the influence of propofol and mean arterial pressure were constructed.

Results
A three-compartment model, including a lag time accounting for the venous blood sampling, adequately described the concentration-time curves of alfentanil Propofol decreased the elimination clearance of alfentanil by 15%, rapid distribution clearance by 68%, slow distribution clearance by 51%, and lag time by 62%. Mean arterial pressure and systemic vascular resistance were significantly lower in the presence of propofol. Scaling the pharmacokinetic parameters to the mean arterial pressure instead of propofol improved the model.

Conclusions
Propofol alters the pharmacokinetics of alfentanil. Hemodynamic changes induced by propofol may have an important influence on the pharmacokinetics of alfentanil.
The Neurologic and Adaptive Capacity Score Is Not a Reliable Method of Newborn Evaluation
Authors: Halpern Stephen H. , Littleford Judith A. , Brockhurst Nicole J. , Youngs Paul J. , Malik Nariman , Owen Holly C. 
Published: November 2003

Background
The Neurologic and Adaptive Capacity Score (NACS) is a multi-item scale that was published in 1982 to measure the effects of intrapartum drugs on the neonate. Although this scoring system has been widely used in obstetric anesthesia research, studies confirming its reliability have not been published. The purpose of this study was to assess the reliability of the NACS.

Methods
Two teams of observers were trained to perform the NACS on healthy, term neonates born in the vertex presentation. Two examinations were performed on each neonate within the first 2.5 h of life. Simultaneous (or "split-half") reliability was assessed using the alpha coefficient. Test-retest reliability was assessed using the intraclass correlation coefficient. The test was considered to be reliable if a was greater than 0.7 and the intraclass correlation coefficient was greater than 0.6.

Results
Two hundred babies were studied. The a was 0.47 and the intraclass correlation coefficient was 0.38 (95% confidence interval, 0.24-0.52).

Conclusions
The NACS had poor reliability both on simultaneous testing and in the test-retest situation when used to evaluate term, healthy neonates. The authors suggest that other measures need to be developed to evaluate the effect of intrapartum drug administration in the neonate. Health measurement scales should undergo rigorous assessment for reliability and validity before they are used in clinical practice or for research purposes.
The Effect of Sevoflurane and Desflurane on Upper Airway Reactivity
Authors: Klock P. Allan , Czeslick Elke G. , Klafta Jerome M. , Ovassapian Andranik , Moss Jonathan 
Published: November 2003

Background
Although bronchial reactivity can be assessed by changes in airway resistance, there is no well-accepted measure of upper airway reactivity during anesthesia. The authors used the stimulus of endotracheal tube cuff inflation and deflation to assess changes in airway reactivity in patients anesthetized with sevoflurane and desflurane.

Methods
Sixty-four patients classified as American Society of Anesthesiologists physical status I or II participated in this randomized, double-blind study. Patients were anesthetized with either sevoflurane or desflurane at 1.0 and 1.8 minimum alveolar concentration (MAC). The trachea was stimulated by inflating the endotracheal tube cuff. A blinded observer assessed the severity of patient response to the stimulus and changes in hemodynamic variables. The process was repeated at the second MAC treatment condition.

Results
At 1.0 MAC, patients anesthetized with desflurane had a more intense response and a greater likelihood of significant coughing and associated hemodynamic changes (both at P < 0.05). At 1.8 MAC, sevoflurane and desflurane both suppressed clinically significant responses to tracheal stimulation. Interrater reliability was excellent for this measure of upper airway reactivity (P < 0.001).

Conclusions
The assessment of the cough response to tracheal stimulation by endotracheal tube cuff inflation is a reliable and clinically meaningful measure of upper airway reactivity. At 1.0 MAC, sevoflurane is superior to desflurane for suppressing moderate and severe responses to this stimulus.
Comparison of the Intubating Laryngeal Mask Airway with the Fiberoptic Intubation in Anticipated Difficult Airway Management
Authors: Langeron Olivier , Semjen François , Bourgain Jean-Louis , Marsac Alain , Cros Anne-Marie 
Published: November 2003

Background
The intubating laryngeal mask airway (ILMA; Fastrach; Laryngeal Mask Company, Henley-on-Thames, UK) may provide an alternative technique to fiberoptic intubation (FIB) to facilitate the management of the anticipated difficult airway. The authors therefore compared the effectiveness of the ILMA with FIB in patients with anticipated difficult intubation.

Methods
One hundred patients, with at least one difficult intubation criteria (Mallampati class III or IV, thyromental distance < 65 mm, interincisor distance < 35 mm) were enrolled (FIB group, n = 49; ILMA group, n = 51) in this prospective randomized study. Anesthesia was induced with propofol and maintained with alfentanil and propofol after an efficient mask ventilation has been demonstrated. The success of the technique (within three attempts), the number of attempts, duration of the successful attempt, and adverse events (oxygen saturation < 90%, bleeding) were recorded.

Results
The rate of successful tracheal intubation with ILMA was 94% and comparable with FIB (92%). The number of attempts and the time to succeed were not significantly different between groups. In case of failure of the first technique, the alternative technique always succeeded. Failures in FIB group were related to oxygen desaturation (oxygen saturation < 90%) and bleeding, and to previous cervical radiotherapy in the ILMA group. Adverse events occurred significantly more frequently in FIB group than in ILMA group (18 vs. 0%, P < 0.05).

Conclusion
The authors obtained a high success rate and comparable duration of tracheal intubation with ILMA and FIB techniques. In patients with previous cervical radiotherapy, the use of ILMA cannot be recommended. Nevertheless, the use of the ILMA was associated with fewer adverse events.
Subanesthetic Isoflurane Affects Task-induced Brain Activation in a Highly Specific Manner
Authors: Heinke Wolfgang , Schwarzbauer Christian 
Published: November 2003

Background
Functional magnetic resonance imaging of blood oxygenation level-dependent signal changes offers a very promising approach to investigate activated neural networks during anesthesia.

Methods
Sixteen healthy male volunteers, assigned into two groups of eight subjects (isoflurane group, control group), were investigated by functional magnetic resonance imaging during different experimental conditions. The isoflurane group successively breathed air (baseline condition), isoflurane in air (0.42 vol% inspiratory; isoflurane condition) and air again (recovery condition) while performing a visual search task, whereas the control group breathed air during all experimental conditions. Functional magnetic resonance images were acquired during the entire experimental session. In addition, reaction times and error rates were recorded.

Results
A significant isoflurane-related decrease (z > 3.1 corresponding to P < 0.001) in task-induced brain activation was found in three distinct cortical regions: the right anterio-superior insula (Talairach coordinates: x = 32, y = 22, z = 8) and the banks of the left and right intraparietal sulcus (Talairach coordinates: x = -34, y = -36, z = 32; x = 22, y = -60, z = 41, respectively). Subcortical structures (lateral geniculate nucleus) and the primary cortices (motor cortex, visual cortex) were not affected. All measured parameters indicated a nearly complete recovery of the affected networks within 5 min.

Conclusions
Our findings indicate that subanesthetic isoflurane affected task-induced activation in specific neural networks rather than causing a global decrease in functional activation.
Lack of Degradation of Sevoflurane by a New Carbon Dioxide Absorbent in Humans
Authors: Mchaourab Ali , Arain Shahbaz R. , Ebert Thomas J. 
Published: November 2003

Background
Potent inhaled anesthetics degrade in the presence of the strong bases (sodium hydroxide or potassium hydroxide) in carbon dioxide (CO2) absorbents. A new absorbent, Amsorb (Armstrong Medical Ltd., Coleraine, Northern Ireland), does not employ these strong bases. This study compared the scavenging efficacy and compound A production of two commercially available absorbents (soda lime and barium hydroxide lime) with Amsorb in humans undergoing general anesthesia.

Methods
Four healthy volunteers were anesthetized on different days with desflurane, sevoflurane, enflurane, and isoflurane. End-tidal carbon dioxide (ETCO2) and anesthetic concentrations were measured with infrared spectroscopy; blood pressure and arterial blood gases were obtained from a radial artery catheter. Each anesthetic exposure lasted 3 h, during which the three fresh (normally hydrated) CO2 absorbents were used for a period of 1 h each. Anesthesia was administered with a fresh gas flow rate of 2 l/min of air:oxygen (50:50). Tidal volume was 10 ml/kg; respiratory rate was 8 breaths/min. Arterial blood gases were obtained at baseline and after each hour. Inspired concentrations of compound A were measured after 15, 30, and 60 min of anesthetic administration for each CO2 absorbent.

Results
Arterial blood gases and ETCO2 were not different among three CO2 absorbents. During sevoflurane, compound A formed with barium hydroxide lime and soda lime, but not with Amsorb.

Conclusions
This new CO2 absorbent effectively scavenged CO2 and was not associated with compound A production.
Moderate Hypothermia Depresses Arterial Baroreflex Control of Heart Rate during, and Delays Its Recovery after, General Anesthesia in Humans
Authors: Tanaka Makoto , Nagasaki Go , Nishikawa Toshiaki 
Published: November 2003

Background
Effects of hypothermia on arterial baroreflex function during, and on its recovery after, general anesthesia were examined in humans.

Methods
Twenty healthy volunteers were randomly assigned to a normothermic group (n = 10 each, active forced-air warming) or to a hypothermic group (no active warming) during anesthesia. Measurements of R-R intervals and systolic blood pressure were made at conscious baseline and at 20, 60, and 120 min after the induction and 20, 60, 120, and 180 min after emergence from general anesthesia with sevoflurane for 2 h. Ventilation was mechanically controlled, and end-tidal sevoflurane concentration was maintained at 2% during anesthesia. Baroreflex responses were triggered by bolus intravenous injections of phenylephrine and nitroprusside. The linear portions of the baroreflex curves relating R-R intervals and systolic blood pressure were determined to obtain baroslopes.

Results
During anesthesia, the mean lowest tympanic temperature of the hypothermia group (33.9+/-0.5 degrees C [mean +/- SD]) was significantly lower than that of the normothermia group (36.1+/-0.7 degrees C, P < 0.001). The baroslopes of the pressor and depressor tests were decreased by 19-39% during and by 27-53% after general anesthesia in the hypothermia group, compared with the normothermia group (P < 0.05). The baroslopes of the normothermia group returned to the baseline values at 60 min after anesthesia, whereas the pressor test sensitivity of the hypothermia group was significantly less than that of the normothermia group for the entire course of recovery.

Conclusions
The results indicate that moderate hypothermia enhances anesthesia-induced depression of baroreflex function in anesthetized humans and delays its recovery after general anesthesia.
Impact of Spinal Cord Stimulation on Sensory Characteristics in Complex Regional Pain Syndrome Type I
Authors: Kemler Marius A. , Reulen Jos P. H. , Barendse Gerard A. M. , van Kleef Maarten , de Vet Henrica C. W. , van den Wildenberg Frans A. J. M. 
Published: November 2003

Background
A randomized trial was performed to assess the effect of spinal cord stimulation (SCS) on detection and pain thresholds for pressure, warmth, and cold and on the extent of mechanical hyperalgesia in patients with chronic complex regional pain syndrome type I.

Methods
Fifty-four chronic complex regional pain syndrome type I patients were randomized to receive both SCS and physical therapy (SCS+PT; n = 36), or to receive only physical therapy (PT; n = 18). Twenty-four SCS+PT patients responded positively to trial stimulation and underwent SCS implantation. During a 12-month follow-up period, six quantitative sensory testing sessions were performed. The main analysis compared 24 SCS patients with 29 nonimplanted patients--one PT patient was excluded.

Results
SCS showed no effect on detection thresholds for warmth and cold or on pain thresholds for any sensation. The pressure detection threshold initially increased by SCS, but after 3 months, pressure detection thresholds returned to normal. Mechanical hyperalgesia, both dynamic and static, was reduced slightly with SCS.

Conclusions
Although SCS has previously been shown to cause a significant pain reduction in complex regional pain syndrome type I, the treatment has no long-term effect on detection and pain thresholds for pressure, warmth, or cold. The treatment seems to have only minimal influence on mechanical hyperalgesia.