bluuebunny/crossref_metadata_2025_split huggingface dataset:
Indocyanine Green
Authors: Dietz Friederike B. , Jaffe Richard A. 
Published: November 2003

Background
The inadvertent intravascular injection of a local anesthetic during epidural anesthesia is an uncommon but potentially serious complication. Epinephrine, the most commonly used marker, does not provide sufficient sensitivity to exclude intravascular injection in all patient populations. The dye indocyanine green (ICG) has been proposed as an alternative marker. It has been demonstrated that ICG could be used to detect intravascular injections with a simple transcutaneous spectrophotometric technique. Although the safety of intravenous ICG is well documented, its neurotoxic potential requires careful study given the probability of inadvertent intrathecal injection during test injections used to verify epidural catheter placement.

Methods
In this study, the authors investigated the neurophysiologic effects of clinically relevant concentrations of ICG (range, 28.6-286 microm) on single myelinated and unmyelinated dorsal root axons in rats by measuring effects on impulse generation and conduction.

Results
In contrast to the apparent absence of toxicity when injected intravenously, ICG applied to intact dorsal roots at concentrations likely to be encountered with an epidural test dose produced long-lasting conduction block (21 of 26 axons) or spontaneous bursting activity (7 of 26 axons) in myelinated and unmyelinated dorsal root axons.

Conclusion
Given this apparent neurotoxicity, ICG should not be used when intrathecal or nerve root injection is possible.
Activation of Peripheral Excitatory Amino Acid Receptors Decreases the Duration of Local Anesthesia
Authors: Cairns Brian E. , Gambarota Giulio , Dunning Patricia S. , Mulkern Robert V. , Berde Charles B. 
Published: November 2003

Background
Postsurgical wound infiltration with the -methyl-d-aspartate receptor antagonist ketamine and bupivacaine can significantly prolong the duration of local anesthesia. One possible mechanism for this effect is that increased glutamate concentrations, caused by tissue damage, sensitize nociceptive primary afferent fibers through activation of peripheral excitatory amino acid receptors.

Methods
The effect of intramuscular injection of hyper-tonic glutamate (1,000 mm), dextrose (1,400 mm), glutamate (1,000 mm) with the broad spectrum excitatory amino acid receptor antagonist kynurenate (100 mm), or isotonic saline (155 mm) on the duration of masseter muscle afferent fiber blockade after lidocaine (37 mm [1%], 10 microl) infiltration, on muscle edema formation and on muscle blood flow was examined.

Results
Injection of either glutamate or dextrose significantly shortened the duration of lidocaine blocks compared with isotonic saline; however, block duration was significantly shorter after glutamate than after dextrose. Injection of glutamate, but not isotonic saline, dextrose, or glutamate with kynurenate, significantly decreased the mechanical threshold of muscle afferent fibers. Injection of glutamate, dextrose, or glutamate with kynurenate produced equivalent large, long-lasting (> 60 min) edemas with high initial peak extracellular water content. Peak extracellular water decreased more rapidly when kynurenate was coinjected with glutamate. Both glutamate and dextrose significantly increased muscle blood flow for 30 min after injection. Glutamate-induced increases in blood flow were attenuated by kynurenate.

Conclusions
These results suggest that shortened lidocaine block durations observed after glutamate injection into the masseter muscle result from sensitization of afferent fibers as well as increases of peak extracellular water content and blood flow in masseter muscle. These effects of glutamate are mediated in part through activation of peripheral excitatory amino acid receptors.
Do They Understand? (Part II)
Authors: Tait Alan R. , Voepel-Lewis Terri , Malviya Shobha 
Published: November 2003

Background
Participation of children in clinical research requires not only parental permission but also the assent of the child. Although there is no fixed age at which assent should be sought, investigators should obtain assent from children considered able to provide it. This study was designed to determine children's understanding of the elements of disclosure for studies in which they had assented to participate.

Methods
The study population included 102 children aged 7-18 yr who had given their assent to participate in a clinical anesthesia or surgical study. Children were interviewed using a semistructured format to determine their understanding of eight core elements of disclosure for the study to which they had agreed to participate. Two independent assessors scored the children's levels of understanding of these elements.

Results
The children's perceived level of understanding of the elements of disclosure was significantly greater than their measured understanding (7.0 +/- 2.4 vs 5.3 +/- 2.7, 0-10 scale; P< 0.0001). Complete understanding of the elements of disclosure for all children ranged from 30.4 to 89.4%. Children aged more than 11 yr had significantly greater understanding compared with younger children, particularly with respect to understanding of the study protocol, the benefits, and the freedom to withdraw.

Conclusions
Children approached for their assent to participate in a clinical anesthesia or surgery study have limited understanding of the elements of disclosure and their role as a research participant, particularly if they are aged less than 11 yr.
Correlation of Approximate Entropy, Bispectral Index, and Spectral Edge Frequency 95 (SEF95) with Clinical Signs of “Anesthetic Depth” during Coadministration of Propofol and Remifentanil
Authors: Bruhn Jörgen , Bouillon Thomas W. , Radulescu Lucian , Hoeft Andreas , Bertaccini Edward , Shafer Steven L. 
Published: November 2003

Background
Several studies relating electroencephalogram parameter values to clinical endpoints using a single (mostly hypnotic) drug at relatively low levels of central nervous system depression (sedation) have been published. However, the usefulness of a parameter derived from the electroencephalogram for clinical anesthesia largely depends on its ability to predict the response to stimuli of different intensity or painfulness under a combination of a hypnotic and an (opioid) analgesic. This study was designed to evaluate the predictive performance of spectral edge frequency 95 (SEF95), BIS, and approximate entropy for the response to increasingly intense stimuli under different concentrations of both propofol and remifentanil in the therapeutic range.

Methods
Ten healthy male and ten healthy female volunteers were studied during coadministration of propofol and remifentanil. After having maintained a specific target concentration for 10 min, the depth of sedation-anesthesia was assessed using the responsiveness component of the Observer's Assessment of Alertness/Sedation (OAA/S) rating scale, which was modified by adding insertion of a laryngeal mask and laryngoscopy. The electroencephalogram derived parameters approximate entropy, bispectral index, and SEF95 were recorded just before sedation level was assessed.

Results
The prediction probability values for approximate entropy were slightly, but not significantly, better than those for bispectral index, SEF95, and the combination of drug concentrations. A much lower prediction ability was observed for tolerance of airway manipulation than for hypnotic endpoints.

Conclusion
Approximate entropy revealed informations on hypnotic and analgesic endpoints using coadministration of propofol and remifentanil comparable to bispectral index, SEF95, and the combination of drug concentrations.
Risk Factors for Adverse Postoperative Outcomes in Children Presenting for Cardiac Surgery with Upper Respiratory Tract Infections
Authors: Malviya Shobha , Voepel-Lewis Terri , Siewert Monica , Pandit Uma A. , Riegger Lori Q. , Tait Alan R. 
Published: November 2003

Background
Otherwise healthy children who present for elective surgery with an upper respiratory infection (URI) may be at risk for perioperative respiratory complications. This risk may be increased in children with congenital heart disease who undergo cardiac surgery while harboring a URI because of their compromised cardiopulmonary status. Therefore, this study was designed to determine the incidence of peri- and postoperative complications in children undergoing cardiac surgery while harboring a URI.

Methods
The study population consisted of 713 children scheduled to undergo cardiac surgery. Of these, 96 had symptoms of URI, and 617 were asymptomatic. Children were followed prospectively from induction of anesthesia to discharge from the hospital to determine the incidence of postoperative respiratory, cardiovascular, neurologic, and surgical adverse events. Duration of postoperative ventilation, time in the intensive care unit (ICU), and length of hospital stay were also recorded.

Results
Children with URIs had a significantly higher incidence of respiratory and multiple postoperative complications than children with no URIs (29.2 vs 17.3% and 25 vs 10.3%, respectively; P< 0.01) and a higher incidence of postoperative bacterial infections (5.2 vs 1.0%; P= 0.01). Furthermore, logistic regression indicated that the presence of a URI was an independent risk factor for multiple postoperative complications and postoperative infections in children undergoing open heart surgery. Children with URIs also stayed longer in the intensive care unit than children with no URIs (75.9 +/- 89.8 h vs 57.7 +/- 63.8, respectively; P< 0.01). However, the overall length of hospital stay was not significantly different (8.4 vs 7.8 days, URI vs non-URI groups; P> 0.05).

Conclusions
The presence of a URI was predictive of postoperative infection and multiple complications in children presenting for cardiac surgery. Despite this, the presence of a URI does not appear to affect the patient's overall length of hospital stay nor the development of long-term sequelae.
Combined Effects of Nitrous Oxide and Propofol on the Dynamic Cerebrovascular Response to Step Changes in End-tidal Pco2in Humans
Authors: Inaba Shin , Sato Jiro , Aono Mitsuo , Numata Tsutomu , Nishino Takashi 
Published: November 2003

Background
Nitrous oxide (N2O) and propofol exhibit directionally opposite effects on the cerebral circulation, vasodilation and vasoconstriction, respectively. The authors investigated an interaction between the two anesthetic agents on the dynamic cerebrovascular response to step changes in end-tidal pressure of carbon dioxide (PetCO2) in humans.

Methods
Participants with no systemic diseases were allocated into two groups, each of which was anesthetized sequentially with two protocols. Patients in group 1 were anesthetized with 30% O2 + 70% N2O. A continuous intravenous infusion of propofol (7-10 mg x kg(-1) x h(-1)) was then added to the N2O. Patients in group 2 were anesthetized first with continuous infusion of propofol (10 mg x kg(-1) h(-1)), and then 30% O2 + 70% N2O was added to the propofol anesthesia. Using transcranial Doppler ultrasonography, blood flow velocity at the middle cerebral artery (FV(MCA)) was measured during a step increase (on-response) followed by a step decrease (off-response) in PetCO2, with PetCO2 ranging between approximately 28 and 50 mmHg. The dynamic FV(MCA)-PetCO2 relationship was analyzed using a mathematical model that was characterized with a pure time delay, and a time constant and a gain each for the on- or off-response.

Results
The addition of propofol to the N2O anesthesia increased the on-response time constant (P < 0.01), whereas the addition of N2O to the propofol anesthesia increased the time constants for on- (P < 0.01) and off-responses (P < 0.05). However, the addition of either anesthetic did not affect the gains.

Conclusions
Propofol and N2O, when one is added to the other, produce similar dynamic FV(MCA) responses to sudden changes in PetCO2. Addition of each anesthetic slows the dynamic response and produces the response whose magnitude is proportional to the baseline FV(MCA).
Caudal Ropivacaine and Neostigmine in Pediatric Surgery
Authors: Turan Alparslan , Memiş Dilek , Başaran Ümit N. , Karamanlıoğlu Beyhan , Süt Necdet 
Published: November 2003

Background
Neostigmine has been added to local anesthetics for different nerve blocks. This study was conducted to evaluate effects of neostigmine when added to ropivacaine for caudal anesthesia.

Methods
We studied children, aged 1-5 yr, undergoing inguinal hernia and hypospadias surgery. After standard induction of anesthesia, Group I received 0.2% ropivacaine 0.5 ml/kg and Group II received 0.2% ropivacaine 0.5 ml/kg with 2 microg/kg neostigmine via the caudal route. Heart rate, mean arterial pressure, and pulse oximetry were recorded before induction, after induction, and then every 10 min after caudal anesthesia. Hemodynamic, Toddler-Preschooler Postoperative Pain Scale pain score, and sedation score values were recorded 30 min after extubation and at hours 2, 4, 6, 12, and 24. A pain score greater than 3/10 resulted in administration of rectal paracetamol.

Results
There were no differences between the groups in demographic and hemodynamic data, duration of surgery and anesthesia, time to extubation, or sedation scores. The pain scores were significantly lower in Group II at 6 and 12 h (P < 0.05). Time to first analgesic requirement was statistically prolonged in Group II (19.2 +/- 5.5h) when compared with Group I (7.1 +/- 5.7 h) (P < 0.05). Total analgesic consumption was statistically larger in Group I (174 +/- 96 mg) when compared with Group II (80 +/- 85.5 mg) (P < 0.05). The incidence of vomiting (3 patients in Group II and 1 patient in Group I) was not statistically significantly different.

Conclusions
The authors found that a single caudal injection of neostigmine when added to ropivacaine offers an advantage over ropivacaine alone for postoperative pain relief in children undergoing genitourinary surgery.
Posterior Approach to the Sciatic Nerve in Adults: Is Euclidean Geometry Still Necessary?
Authors: Franco Carlo D. 
Published: November 2003

Background
Every approach to the sciatic nerve in the buttocks currently requires the identification of pelvic bone structures. The large size of the nerve and its constant trajectory suggest that a simplified approach is possible.

Methods
During the first stage, 24 sciatic nerves in adult cadavers were dissected. The most significant findings were, (1) caudal to the piriformis muscle the sciatic nerve runs parallel to the midline (intergluteal sulcus); (2) the distance between the nerve and the intergluteal sulcus during this course is approximately 10 cm in adults, regardless of their gender, size, or body habits. In the clinical stage 20 blocks were performed at 10 cm from the midline of the buttocks using a nerve stimulator and insulated needles.

Results
All blocks were accomplished in less than 8.5 min. The technique proved easy to teach. Residents performed most of the blocks. Incision time, measured from the time of the injection, was less than 29 min in all cases. There were 18 successful blocks and 2 failures.

Conclusions
Because of the intimate relationship of the sciatic nerve to the bony pelvis, the position of this nerve in the buttocks is constant. Caudal to the piriformis muscle the nerve runs vertically between the ischium and the greater trochanter. The location of this narrow passage, not the buttocks' size, determines the position of the nerve. While the size of the buttocks is variable among different individuals and in the same individual at different stages of adult life, the relationship of the sciatic nerve to the pelvis is constant throughout life. Using this relationship to our advantage, a sciatic block in adults can be accomplished at 10 cm lateral to the intergluteal sulcus without a need for identification of buried structures or line tracings.
The Role of 5-HT1A/BAutoreceptors in the Antinociceptive Effect of Systemic Administration of Acetaminophen
Authors: Roca-Vinardell Aránzazu , Ortega-Alvaro Antonio , Gibert-Rahola Juan , Micó Juan A. 
Published: November 2003

Background
It has been proposed that serotonin participates in the central antinociceptive effect of acetaminophen. The serotonin activity in the brainstem is primarily under the control of 5-HT1A somatodendritic receptors, although some data also suggest the involvement of 5-HT1B receptors. In the presence of serotonin, the blockade of 5-HT(1A/B) receptors at the level of the raphe nuclei leads to an increase in serotonin release in terminal areas, thus improving serotonin functions. This study examines the involvement of 5-HT(1A/B) receptors in the antinociceptive effect of acetaminophen in mice.

Methods
The effects of acetaminophen (600 mg/kg intraperitoneal) followed by different doses of antagonists (WAY 100635 [0.2-0.8 mg/kg subcutaneous] and SB 216641 [0.2-0.8 mg/kg subcutaneous]) or agonists (8-OH-DPAT [0.25-1 mg/kg subcutaneous] and CP 93129 [0.125-0.5 mg/kg subcutaneous]) of 5-HT1A and 5-HT1B receptors, respectively, were determined in the hot-plate test in mice.

Results
Acetaminophen (300-800 mg/kg) showed a dose-dependent antinociceptive effect in the hot-plate test in mice. WAY 100635 (0.2-0.8 mg/kg; 5-HT1A antagonist) induced an increase in the antinociceptive effect of 600 mg/kg acetaminophen, but this increase was not dose related. Conversely, 8-OH-DPAT (0.25-1 mg/kg; 5-HT1A agonist) decreased the antinociceptive effect of acetaminophen. SB 216641 (0.2-0.8 mg/kg; 5-HT1B antagonist) induced a dose-related increase in the antinociceptive effect of acetaminophen, and CP 93129 (0.25 mg/kg; 5-HT1B agonist) significantly decreased the antinociceptive effect of acetaminophen.

Conclusions
These results suggest that the combination of acetaminophen with compounds having 5-HT1A and 5-HT1B antagonist properties could be a new strategy to improve the analgesia of acetaminophen, thanks to its mild serotonergic properties.
Clonidine-induced Neuronal Activation in the Spinal Cord Is Altered after Peripheral Nerve Injury
Authors: Pancaro Carlo , Ma Weiya , Vincler Michelle , Duflo Frederic , Eisenach James C. 
Published: November 2003

Background
Alpha 2 adrenoceptor agonists produce antinociception in normal animals and alleviate mechanical allodynia in animals with nerve injury, although their mechanism of action may differ in these situations. The purpose of this study was to examine the location and number of cells in the spinal cord activated by intrathecal clonidine in these two circumstances and to test whether one class of interneurons, cholinergic, express alpha 2 adrenoceptors.

Methods
Intrathecal saline or clonidine, 10 and 30 microg, was injected in normal rats or those with mechanical allodynia following partial sciatic nerve section. Two hours later, animals were anesthetized and pericardially perfused. The number of cells in superficial and deep dorsal horn laminae at the L4-L5 level immunostained for phosphorylated cAMP response element binding protein (pCREB) were quantified. In separate studies, the authors colocalized alpha2C adrenoceptors with cholinergic neurons.

Results
Intrathecal clonidine increased pCREB immunoreactive cells in both superficial and deep laminae by 50-100% in normal animals. The number of pCREB immunoreactive cells increased in nerve-injured compared to normal rats. Intrathecal clonidine decreased pCREB immunoreactive cells in the deep dorsal horn of injured animals. Alpha2C adrenoceptors colocalized with cholinergic neurons in both superficial and deep dorsal horn.

Discussion
Previous studies suggest a shift in alpha 2 adrenoceptor subtype and the involvement of cholinergic interneurons in antinociception in the spinal cord after nerve injury. The current results suggest that intrathecal clonidine, by direct or indirect methods, increases neuronal activation in normal animals, presumably leading to net inhibition of pain signaling, whereas it reduces the increase in neuronal activity induced by nerve injury.
Noninvasive Cardiac Output Measurement Using Partial Carbon Dioxide Rebreathing Is Less Accurate at Settings of Reduced Minute Ventilation and when Spontaneous Breathing Is Present
Authors: Tachibana Kazuya , Imanaka Hideaki , Takeuchi Muneyuki , Takauchi Yuji , Miyano Hiroshi , Nishimura Masaji 
Published: November 2003

Background
Although evaluation of cardiac output by the partial carbon dioxide rebreathing technique is as accurate as thermodilution techniques under controlled mechanical ventilation, it is less accurate at low tidal volume. It is not clear whether reduced accuracy is due to low tidal volume or low minute ventilation. The effect of spontaneous breathing on the accuracy of partial carbon dioxide rebreathing measurement has not been fully investigated. The objectives of the current study were to investigate whether tidal volume or minute ventilation is the dominant factor for the accuracy, and the accuracy of the technique when spontaneous breathing effort is present.

Methods
The authors enrolled 25 post-cardiac surgery patients in two serial protocols. First, the authors applied three settings of controlled mechanical ventilation in random order: large tidal volume (12 ml/kg), the same minute ventilation with a small tidal volume (6 ml/kg), and 50% decreased minute ventilation with a small tidal volume (6 ml/kg). Second, when the patient recovered spontaneous breathing, the authors applied three conditions of partial ventilatory support in random order: synchronized intermittent mandatory ventilation-pressure support ventilation, pressure support ventilation with an appropriately adjusted rebreathing loop, and pressure support ventilation with the shortest available loop. After establishing steady state conditions, the authors measured cardiac output using both partial carbon dioxide rebreathing and thermodilution methods. The correlation between the data yielded by the two methods was determined by Bland-Altman analysis and linear regression.

Results
Cardiac output with the carbon dioxide rebreathing technique correlated moderately with that measured by thermodilution when minute ventilation was set to maintain normocapnia, regardless of tidal volumes. However, when minute ventilation was set low, the carbon dioxide rebreathing technique underreported cardiac output (y = 0.70x; correlation coefficient, 0.34; bias, -1.73 l/min; precision, 1.27 l/min; limits of agreement, -4.27 to +0.81 l/min). When there was spontaneous breathing, the correlation between the two cardiac output measurements became worse. Carbon dioxide rebreathing increased spontaneous tidal volume and respiratory rate (20% and 30%, respectively, during pressure support ventilation) when the rebreathing loop was adjusted for large tidal volume.

Conclusions
During controlled mechanical ventilation, minute ventilation rather than tidal volume affected the accuracy of cardiac output measurement using the partial carbon dioxide rebreathing technique. When spontaneous breathing is present, the carbon dioxide rebreathing technique is less accurate and increases spontaneous tidal volume and respiratory rate.