bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spinal Anesthesia Speeds Active Postoperative Rewarming
Authors: Szmuk Peter , Ezri Tiberiu , Sessler Daniel I. , Stein Arnold , Geva Daniel 
Published: November 2003

Background
Redistribution of body heat decreases core temperature more during general than regional anesthesia. However, the combination of anesthetic- and sedative-induced inhibition may prevent effective upper-body thermoregulatory responses even during regional anesthesia. The extent to which each type of anesthesia promotes hypothermia thus remains controversial. Accordingly, the authors evaluated intraoperative core hypothermia in patients assigned to receive spinal or general anesthesia. They also tested the hypothesis that the efficacy of active postoperative warming is augmented when spinal anesthesia maintains vasodilation.

Methods
Patients undergoing lower abdominal and leg surgery were randomly assigned to receive general anesthesia (isoflurane and nitrous oxide; n = 20) or spinal anesthesia (bupivacaine; n = 20). Fluids were warmed to 37 degrees C and patients were covered with surgical drapes. However, no other active warming was applied during operation. Ambient temperatures were maintained near 20 degrees C. After operation, patients were warmed with a full-length, forced-air cover set to 43 degrees C. Shivering, when observed, was treated with intravenous meperidine.

Results
The mean spinal analgesia level, which was at the sixth thoracic level during surgery, remained at the T12 dermatome after 90 min after operation. Core temperatures did not differ significantly during surgery and decreased to 34.4 +/- 0.5 degrees C and 34.1 +/- 0.4 degrees C, respectively, in patients given spinal and general anesthesia. After operation, however, core temperatures increased significantly faster (1.2 +/- 0.1 degrees C/h vs. 0.7 +/- 0.2 degrees C/h, mean +/- SD; P < 0.001) in patients given spinal anesthesia. Consequently, patients given spinal anesthesia required less time to rewarm to 36.5 degrees C (122 +/- 28 min vs. 199 +/- 28 min; P < 0.001).

Conclusions
Comparable intraoperative hypothermia during general and regional anesthesia presumably resulted because the combination of spinal anesthesia and meperidine administration obliterated effective peripheral and central thermoregulatory control. Vasodilation increased the rate of core rewarming in patients after operation with residual lower-body sympathetic blocks, suggesting that vasoconstriction decreased peripheral-to-core heat transfer after general anesthesia.
Cerebral Emboli during Cardiac Surgery in Children
Authors: O'Brien James J. , Butterworth John , Hammon John W. , Morris Kristin J. , Phipps Julia M. , Stump David A. 
Published: November 2003

Background
Microemboli occur commonly during cardiac surgery in adults, and, when present, increase the risk of neuropsychological deficits. Their incidence and significance during correction of congenital heart disease is unknown. The authors hypothesized that microemboli would occur before bypass with right-to-left cardiac shunts and would also occur in large numbers when the aortic crossclamp was released in children during repair of congenital heart defects.

Methods
In 25 children studied with carotid artery Doppler, embolic signals were counted and timed in relation to 13 intraoperative events. Patients were classified as either at high risk (obligate right-to-left shunt or uncorrected transposition of the great arteries) or at low risk (net left-to-right shunt or simple obstructive lesions) for paradoxical (venous to arterial) emboli.

Results
The median number of emboli detected was 122 (range, 2-2,664). Forty-two percent of all emboli were detected within 3 min of release of the aortic crossclamp. The high-risk group had significantly more emboli (median, 66; range, 0-116) during the time interval before cardiopulmonary bypass than did the low-risk group (median, 8; range, 0-73), with P < 0.01. There was no significant difference between the high- and low-risk groups in the total number of emboli detected. There was no apparent association between number of emboli and gross neurologic deficits.

Conclusions
Microemboli can be detected in the carotid arteries of children undergoing repair of congenital heart disease and are especially prevalent immediately after release of the aortic crossclamp. The role of emboli in causing neurologic injury in children undergoing repair of congenital heart disease remains to be determined.
Opioid-sparing Effects of a Low-dose Infusion of Naloxone in Patient-administered Morphine Sulfate
Authors: Gan Tong J. , Ginsberg Brian , Glass Peter S. A. , Fortney Jennifer , Jhaveri Rajiv , Perno Rhonda 
Published: November 2003

Background
A naloxone infusion is effective in reducing epidural and intrathecal opioid-related side effects. The use of naloxone infusion concomitant with intravenous morphine patient-controlled analgesia (PCA) has not been evaluated, probably because of an expected direct antagonism of the systemic opioid effect. The authors compared the incidence of morphine-related side effects and the quality of analgesia from two small doses of naloxone infusion.

Methods
Sixty patients classified as American Society of Anesthesiologists physical status 1, 2, or 3 who were scheduled for total abdominal hysterectomies were enrolled in the study. Patients received a standardized general anesthetic. In the postanesthetic care unit, patients received morphine as a PCA. They were randomized to receive either 0.25 microg x kg(-1) x h(-1) naloxone (low dose), 1 microg x kg(-1) x h(-1) (high dose), or saline (placebo) as a continuous infusion. Verbal rating scores for pain, nausea, vomiting, and pruritus; sedation scores; requests for antiemetic; and morphine use were recorded for 24 h. Blood pressure, respiratory rate, and oxyhemoglobin saturation were also monitored.

Results
Sixty patients completed the study. Both naloxone doses were equally effective in reducing the incidence of nausea, vomiting, and pruritus compared with placebo (P < 0.05 by the chi-squared test). There was no difference in the verbal rating scores for pain between the groups. The cumulative morphine use was the lowest in the low-dose group (42.3 +/- 24.1 mg; means +/- SD) compared with the placebo (59.1 +/- 27.4 mg) and high-dose groups (64.7 +/- 33.0 mg) at 24 h (P < 0.05 by analysis of variance). There was no incidence of respiratory depression (<8 breaths/min) and no difference in sedation scores, antiemetic use, respiratory rate, and hemodynamic parameters among the groups.

Conclusions
Naloxone is effective in preventing PCA opioid-related side effects. Naloxone infusion at 0.25 microg x kg(-1) x h(-1) not only attenuates these side effects but appears to reduce postoperative (beyond 4-8 h) opioid requirements. This dosing regimen can be prepared with 400 microg naloxone in 1,000 ml crystalloid given in 24 h to a patient weighing 70 kg.
Midazolam Changes Cerebral Blood Flow in Discrete Brain Regions
Authors: Veselis Robert A. , Reinsel Ruth A. , Beattie Bradley J. , Mawlawi Osama R. , Feshchenko Vladimir A. , DiResta Gene R. , Larson Steven M. , Blasberg Ronald G. 
Published: November 2003

Background
Changes in regional cerebral blood flow (rCBF) determined with H2(15)O positron emission tomographic imaging can identify neural circuits affected by centrally acting drugs.

Methods
Fourteen volunteers received one of two midazolam infusions adjusted according to electroencephalographic response. Low or high midazolam effects were identified using post-hoc spectral analysis of the electroencephalographic response obtained during positron emission tomographic imaging based on the absence or presence of 14-Hz spindle activity. The absolute change in global CBF was calculated, and relative changes in rCBF were determined using statistical parametric mapping with localization to standard stereotactic coordinates.

Results
The low-effect group received 7.5 +/- 1.7 mg midazolam (serum concentrations, 74 +/- 24 ng/ml), and the high-effect group received 9.7 +/- 1.3 mg midazolam (serum concentrations, 129 +/- 48 ng/ml). Midazolam decreased global CBF by 12% from 39.2 +/- 4.1 to 34.4 +/- 6.1 ml x 100 g(-1) x min(-1) (P < 0.02 at a partial pressure of carbon dioxide of 40 mmHg). The rCBF changes in the low-effect group were a subset of the high-effect group. Decreased rCBF (P < 0.001) occurred in the insula, the cingulate gyrus, multiple areas in the prefrontal cortex, the thalamus, and parietal and temporal association areas. Asymmetric changes occurred, particularly in the low-effect group, and were more significant in the left frontal cortex and thalamus and the right insula. Relative rCBF was increased in the occipital areas.

Conclusion
Midazolam causes dose-related changes in rCBF in brain regions associated with the normal functioning of arousal, attention, and memory.
Opioid Effects on Mitogen-activated Protein Kinase Signaling Cascades
Authors: Gutstein Howard B. , Rubie Elizabeth A. , Mansour Alfred , Akil Huda , Woodgett James R. 
Published: November 2003

Background
The molecular mechanisms underlying both beneficial and undesirable opioid actions are poorly understood. Recently, the three currently known mammalian mitogen-activated protein kinase (MAPK) signaling cascades (extracellular signal-related kinase [ERK], stress-activated protein kinase, and p38 kinase) were shown to play important roles in transducing receptor-mediated signaling processes.

Methods
To determine whether any of these kinase cascades were activated by opioids, mu, delta, or kappa opioid receptors were transiently introduced into COS-7 cells together with MAPKs tagged to allow recognition by specific antibodies, and then exposed to opioids. Mitogen-activated protein kinase activation was determined by an in vitro MAPK activation assay. In addition, C6 glioma cells with either mu, delta, or kappa receptors stably introduced were exposed to opioids and MAPK activation determined by in vitro activation assay or antibody detection of activated forms.

Results
Transient experiments in COS cells revealed potent stimulation of ERK by mu and delta receptor activation, weak stimulation of stress-activated protein kinase by all receptor types, and no activation of p38. In stably transfected C6 glioma cells, only ERK activation was observed. Extracellular signal-related kinase induction was rapid, peaking 5 min after stimulation, and its activation was receptor-type specific. Mu and delta receptor stimulation activated ERK, but kappa stimulation did not.

Conclusions
These results show that acute opioid signaling is not only inhibitory, but can strongly activate an important signaling cascade. Extracellular signal-related kinase activation may contribute to desirable responses to opioids, such as analgesia and sedation, and also to undesirable adaptive responses, such as tolerance, physical dependence, and possibly addiction. Further study of this system could provide greater insight into the molecular mechanisms underlying these clinical problems.
Comparison of the Effects of Propofol and Pentobarbital on Neurologic Outcome and Cerebral Infarct Size after Temporary Focal Ischemia in the Rat
Authors: Pittman Janet E. , Sheng Huaxin , Pearlstein Robert , Brinkhouse Ann , Dexter Franklin , Warner David S. 
Published: November 2003

Background
Although propofol is known to have effects on cerebral physiology similar to the barbiturates, a direct comparison of the relative effects of these drugs on outcome from cerebral ischemia has not been performed. The authors postulated that pentobarbital or propofol would yield similar effects on neurologic and histologic outcome from temporary focal ischemia in the rat.

Methods
Wistar rats were anesthetized with sufficient doses of pentobarbital (n = 20) or propofol (n = 20) to cause electroencephalographic burst suppression. The middle cerebral artery was then occluded for 75 min. Animals were awakened 4-6 h after onset of reperfusion and allowed to recover for 1 week. Neurologic function and infarct size were then assessed.

Results
Relevant physiologic values were similar between groups during ischemia and early reperfusion. No difference between groups was observed for severity of hemiparesis (P = 0.10). Total cerebral infarct volumes (median +/- quartile deviation) were similar for the two groups (pentobarbital = 190 +/- 36 mm3; propofol = 200 +/- 24 mm3, P = 0.35).

Conclusion
Neurologic and histologic outcome were similar in pentobarbital or propofol anesthetized rats undergoing temporary focal cerebral ischemia and a 1-week recovery interval.
Atelectasis Is a Major Cause of Hypoxemia and Shunt after Cardiopulmonary Bypass
Authors: Magnusson Lennart , Zemgulis Vitas , Wicky Stephan , Tyden Hans , Thelin Stefan , Hedenstierna Goran 
Published: November 2003

Background
Respiratory failure after cardiopulmonary bypass (CPB) remains a major complication after cardiac surgery. The authors tested the hypothesis that atelectasis is an important factor responsible for the increase in intrapulmonary shunt after CPB.

Methods
Six pigs received standard CPB (bypass group). Six other pigs had the same surgery but without CPB (sternotomy group). Another six pigs were anesthetized for the same duration but without any surgery (control group). The ventilation-perfusion distribution was measured with the inert gases technique, extravascular lung water was quantified by the double-indicator distribution technique, and atelectasis was analyzed by computed tomography.

Results
Intrapulmonary shunt increased markedly after bypass but was unchanged over time in the control group (17.9 +/- 6.2% vs. 3.5 +/- 1.2%; P < 0.0001). Shunt also increased in the sternotomy group (10 +/- 2.6%; P < 0.01 compared with baseline) but was significantly lower than in the bypass group (P < 0.01). Extravascular lung water was not significantly altered in any group. The pigs in the bypass group showed extensive atelectasis (32.3 +/- 28.7%), which was significantly larger than in the two other groups. The pigs in the sternotomy group showed less atelectasis (4.1 +/- 1.9%) but still more (P < 0.05) than the controls (1.1 +/- 1.6%). There was good correlation between shunt and atelectasis when all data were pooled (R2 = 0.67; P < 0.0001).

Conclusions
Atelectasis is produced to a much larger extent after CPB than after anesthesia alone or with sternotomy and it explains most of the marked post-CPB increase in shunt and hypoxemia. Surgery per se contributes to a lesser extent to postoperative atelectasis and gas exchange impairment.
Riluzole Blocks Dopamine Release Evoked by N-methyl-D-aspartate, Kainate, and Veratridine in the Rat Striatum
Authors: Keita Hawa , Lepouse Claire , Henzel Danielle , Desmonts Jean-Marie , Mantz Jean 
Published: November 2003

Background
Dopamine (DA) is released in large amounts during cerebral ischemia and may exacerbate tissue damage. Riluzole (54274 RP) is a recently developed agent that depresses glutamate neurotransmission in the central nervous system (CNS) and that may protect against ischemic injury in some animal models. Because glutamate stimulates the release of DA in the striatum, the authors hypothesized that riluzole could antagonize DA release in this structure.

Methods
Assay for DA release consisted of superfusing 3H-DA preloaded synaptosomes with artificial cerebrospinal fluid (1 ml/min, 37 degrees C) and measuring the radioactivity obtained from 1-min fractions over 22 min, first in the absence of any treatment (spontaneous release, 8 min), then in the presence of depolarizing agents combined with riluzole (0.1-100 microM, 5 min), and finally with no pharmacologic stimulation (9 min). The following depolarizing agents were tested: KCl (9, 15 mM), veratridine (0.01-1 microM), N-methyl-D-aspartate (NMDA, 0.1-1 mM), kainate (0.1-1 mM), and nicotine (0.01-0.5 mM). Assay for DA uptake was performed by measuring the radioactivity incorporated in synaptosomes incubated with 3H-DA (44 nM; 5 min; 37 degrees C).

Results
All depolarizing agents produced a significant, concentration-related increase from basal 3H-DA release. Riluzole was found to decrease the release induced by veratridine (1 microM), NMDA (1 mM), and kainate (1 mM) in a significant, concentration-related manner (IC50 = 9.5 microM, 1.6 microM, and 5.8 microM for veratridine, NMDA, and kainate, respectively). In contrast, it did not affect the release elicited by either KCl or nicotine. Riluzole had no significant effect on the specific 3H-DA uptake.

Conclusions
Riluzole produced a potent blockade of the release of DA mediated by activation of presynaptic sodium channels, NMDA, and kainate receptors. Depression of glutamate transmission together with blockade of DA release may contribute to the actions of this agent in vivo.
Ionic Basis of the Differential Effects of Intravenous Anesthetics on Erythromycin-induced Prolongation of Ventricular Repolarization in the Guinea Pig Heart
Authors: Morey Timothy E. , Martynyuk Anatoly E. , Napolitano Charles A. , Raatikainen M. J. Pekka , Guyton Thomas S. , Dennis Donn M. 
Published: November 2003

Background
Dysrhythmias and death occur in patients with acquired long QT syndrome (LQTS). Little information exists regarding interactions between anesthetics and drugs that prolong ventricular repolarization. Therefore the effects of three commonly used intravenous anesthetics on ventricular repolarization were investigated in the setting of drug-induced, long QT syndrome.

Methods
The effects of increasing concentrations (0, 10, 25, and 50 microM) of propofol, ketamine, and thiopental on ventricular repolarization were evaluated by measuring the monophasic action potential duration at 90% repolarization (MAPD90) in guinea pig Langendorff-perfused hearts in the absence or presence of erythromycin (100 microM). If an anesthetic enhanced erythromycin-induced prolongation of MAPD90, its effects on the delayed rectifier (I[K]) and inward rectifier (I[Kl]) potassium currents were measured using the whole-cell patch-clamp technique.

Results
At clinically relevant concentrations, only thiopental significantly modulated erythromycin's effect on MAPD90. Thiopental at 10, 25, and 50 microM prolonged MAPD90 from a control of 163 +/- 6 ms by 18 +/- 4, 30 +/- 3, and 31 +/- 4 ms, respectively. In a separate group, erythromycin prolonged MAPD90 from 155 +/- 2 ms to 171 +/- 2 ms (n = 21, P < 0.001). In the presence of erythromycin, thiopental at 10, 25, and 50 microM caused significantly greater prolongation from a control of 171 +/- 2 ms by 39 +/- 2, 58 +/- 3, and 72 +/- 6 ms, respectively. Whole-cell patch-clamp experiments indicated that thiopental inhibited I(K) and I(Kl).

Conclusions
Intravenous anesthetics caused markedly different effects on ventricular repolarization. Thiopental, unlike propofol and ketamine, potentiated the effects of erythromycin on ventricular repolarization by inhibiting I(K) and I(Kl).
The Intubation Difficulty Scale (IDS)
Authors: Adnet Frederic , Borron Stephen W. , Racine Stephane X. , Clemessy Jean-Luc , Fournier Jean-Luc , Plaisance Patrick , Lapandry Claude 
Published: November 2003

Background
A quantitative scale of intubation difficulty would be useful for objectively comparing the complexity of endotracheal intubations. The authors have developed a quantitative score that can be used to evaluate intubating conditions and techniques with the aim of determining the relative values of predictive factors of intubation difficulty and of the techniques used to decrease such difficulties.

Methods
An Intubation Difficulty Scale (IDS) was developed, based on parameters known to be associated with difficult intubation. It was then evaluated prospectively in a group of 311 consecutive prehospital intubations and 315 intubations in an operating room. In the operating room, the IDS was compared with two other parameters: the time to completion of intubation and the visual analog scale (VAS). Time was measured by an independent observer. Operators in both groups completed a checklist regarding the conditions of intubation.

Results
There is a good correlation between the IDS scale and the VAS assessment of difficulty and time to completion of intubation. VAS and time to completion have a significant but lesser correlation to each other. Comparison of IDS with operator-assessed subjective categorical impression of difficulty by Kruskall-Wallis was statistically significant.

Conclusions
The IDS correlates with but is less subjective than the VAS and categorical classification. IDS correlates with time to intubation, but it offers details regarding the difficulty encountered that time alone does not. This score may not only aid in evaluation of factors linked to difficult intubations, but it may provide a uniform approach to comparing studies related to this subject.
Greater Incidence of Delirium during Recovery from Sevoflurane Anesthesia in Preschool Boys
Authors: Aono Jun , Ueda Wasa , Mamiya Kikyo , Takimoto Eri , Manabe Masanobu 
Published: November 2003

Background
In the authors' clinical experience, preschool children are more likely to show delirium after sevoflurane than are older children.

Methods
Sixty-three preschool boys aged 3-5 yr (classified as American Society of Anesthesiologists [ASA] physical status I), and 53 school-age boys aged 6-10 yr (ASA physical status I) who underwent minor urologic surgery were randomly assigned to receive either halothane or sevoflurane, thus creating four groups: preschool-halothane (n = 32), preschool-sevoflurane (n = 31), school-halothane (n = 27), and school-sevoflurane (n = 26). Anesthesia was induced by inhalation of halothane or sevoflurane in oxygen and was maintained at 1 minimum alveolar concentration of each agent throughout surgery. For intra- and postoperative analgesia, caudal block with 0.5-1.0 ml/kg 0.25% plain bupivacaine and topical infiltration with 3-5 ml 1% lidocaine were provided for all patients. Recovery characteristics and incidence of delirium on emergence were compared among the four groups.

Results
Two patients in the preschool-halothane group, one in the preschool-sevoflurane group, and one in the school-halothane group were excluded from the comparison because of insufficient analgesia or agitation before induction. In both age groups, the time to emergence from sevoflurane was significantly faster (about 3 min) than from halothane. The incidence of delirium during recovery in the preschool-sevoflurane group (40%) was significantly greater than that in the other groups (preschool-halothane, 10%; school-halothane, 15.4%; school-sevoflurane, 11.5%).

Conclusion
Sevoflurane provided quicker emergence and early recovery compared with halothane, but the incidence of delirium was greater in preschool boys after sevoflurane.