bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Exogenous Intravenous Glucose on Plasma Glucose and Lipid Homeostasis in Anesthetized Infants
Authors: Nishina Kahoru , Mikawa Katsuya , Maekawa Nobuhiro , Asano Migiwa , Obara Hidefumi 
Published: November 2003

Background
Whether intravenous glucose administration to infants during anesthesia is necessary remains to be resolved. The current study was designed to investigate the effect of exogenous glucose infusion on plasma glucose and lipid homeostasis in infants undergoing minor surgery.

Methods
Sixty infants (inpatients, ASA physical status 1) between 1 and 11 months of age were divided randomly into three groups as follows: LR group, lactated Ringer's solution (LR) alone; D2LR group, 2% glucose in LR; and D5LR group, 5% glucose in LR. Anesthesia was induced and maintained with halothane and nitrous oxide in oxygen. All fluids were infused at a rate of 6 ml.kg-1.h-1 until 1 h after surgery. Plasma concentrations of glucose, nonesterified fatty acids, ketone bodies, insulin, and cortisol were determined at induction of anesthesia, at the end of surgery, and 1 h after surgery.

Results
No infants in the three groups had hypoglycemia (< 50 mg.dl-1) throughout the study. In the LR group, plasma glucose concentration remained unchanged perioperatively compared with the basal values (at induction), whereas in the D2LR group, it increased during surgery but remained normoglycemic. In the D5LR group, plasma glucose concentration increased markedly both during and after surgery. In 6 of 20 infants, plasma glucose was greater than 200 mg.dl-1 at the end of surgery. In 8 of 20 infants receiving glucose-free infusion, plasma glucose concentrations decreased at the end of surgery. In contrast, the plasma glucose concentration increased in infants receiving glucose infusion. In the LR group, plasma concentrations of nonesterified fatty acids and ketone bodies increased at the end of and after surgery, suggesting lipid mobilization. The base excess decreased in the LR groups as concentration of the ketone bodies increased. Plasma insulin concentrations increased in the D2LR and D5LR groups and decreased after surgery in infants receiving a glucose-free solution. No intergroup differences in plasma cortisol concentrations existed at any sample point.

Conclusions
These data indicate that, in otherwise healthy infants undergoing minor surgery, intravenous infusion of 2% glucose may be sufficient to maintain plasma glucose concentrations within physiologic ranges and to prevent a compensatory increase in lipid mobilization (lipolysis) when fluids are infused at a rate of 6 ml.kg-1.h-1. However, there are limitations in extrapolating the results to neonates.
Theoretical Analysis of Cerebral Venous Blood Hemoglobin Oxygen Saturation as an Index of Cerebral Oxygenation during Hypothermic Cardiopulmonary Bypass
Authors: Dexter Franklin , Hindman Bradley J. 
Published: November 2003

Background
Jugular venous catheters and near-infrared spectroscopy can measure cerebral venous blood hemoglobin oxygen saturation (SvO2). We used computer simulation to characterize the relation between Sv02 and cerebral metabolic rate for oxygen (CMR02) during hypothermic cardiopulmonary bypass (CPB).

Methods
We developed a theoretical model of cerebral oxygen consumption and blood-brain oxygen transfer. Our model included the temperature dependence of blood and brain oxygen solubility; the temperature, age, and acid-base dependence of hemoglobin oxygen dissociation; and the temperature and age dependence of CMRO2. We simulated cerebral blood flow reductions that decreased Sv02 and CMR02.

Results
Our model predicts the relation between CMR02 and Sv02 to be dependent on temperature, because of a shift of the oxygen partial pressure at which hemoglobin oxygen saturation equals 0.50. For example, during normothermic CPB, Sv02 can decrease to 30% before CMR02 will decrease to less than 90% of normal. In contrast, for alpha-stat management of infants at 17 degrees C, Sv02 must be maintained at greater than 95% to maintain CMR02 at greater than 90% of its temperature appropriate value.

Conclusions
High Sv02 observed during hypothermic CPB may indicate impaired oxygen transfer from hemoglobin to brain, not "luxury perfusion." The relation between Sv02 and CMR02 depends dramatically on the temperature of the patient. Sv02 per se may not be reliable index of normal CMR02 during hypothermic CPB.
Renal Function in Patients with High Serum Fluoride Concentrations after Prolonged Sevoflurane Anesthesia
Authors: Higuchi Hideyuki , Sumikura Hiroyuki , Sumita Shinji , Arimura Shinya , Takamatsu Futoshi , Kanno Masuyuki , Satoh Tetsuo 
Published: November 2003

Background
In studies of methoxyflurane-induced nephrotoxicity, renal-concentrating impairment has been observed only when serum inorganic fluoride concentrations exceed 50 microM. Prolonged sevoflurane anesthesia can result in serum inorganic fluoride concentrations in excess of 50 microM. The authors compared renal function after prolonged sevoflurane anesthesia with that after isoflurane anesthesia. In addition, they measured urinary excretion of N-acetyl-beta-glucosaminidase (NAG), a sensitive index of renal tubular damage, during the 3-day period after anesthesia.

Methods
Thirty-four healthy patients who underwent either sevoflurane (23 patients) or isoflurane (11 patients) anesthesia at a total gas flow of 61/min for orthopedic surgery scheduled to last at least 5 h were studied. At 16.5 h after cessation of anesthesia, patients were administered 10 units of vasopressin and urine was collected frequently thereafter for evaluation of urinary osmolality. In addition, urinary excretion of NAG was measured before and on days 1-3 after anesthesia. Based on whether peak fluoride concentrations exceeded 50 microM, 23 patients anesthetized with sevoflurane were assigned to a sevofluranehigh group (> 50 microM) or a sevofluranelow (< 50 microM) group.

Results
The eight patients in the sevofluranehigh group had a mean peak fluoride concentration of 57.5 +/- 4.3 microM. A significant, albeit weak, inverse correlation was found between peak fluoride concentration and maximal urinary osmolality after the injection of vasopressin (r = -0.42, P < 0.05). Mean maximum urinary osmolality tended to be lower in the sevofluranehigh group (681 +/- 60 mOsm/kg) than in the other two groups after administration of vasopressin, although the difference among the three groups did not quite reach a statistical significance (P = 0.068). One patient had a transient concentrating defect (maximum urinary osmolality = 390 mOsm/kg) on day 1 after anesthesia. Urinary excretion of NAG in both the sevofluranehigh and sevofluranelow groups was greater on days 2 and 3 after anesthesia than before anesthesia. The increase in urinary NAG excretion was dose related with sevoflurane, but there was no difference in results of routine laboratory renal tests on days 2 and 3 after anesthesia among the three groups.

Conclusions
The authors concluded that sevoflurane anesthesia results in increased serum fluoride concentration, a tendency toward decreased maximal ability to concentrate urine, and increased excretion of NAG. However, the increase in urinary NAG excretion was not indicative of clinically significant renal damage in these patients with no preexisting renal disease.
Morphine Inhibits Spontaneous and Cytokine-enhanced Natural Killer Cell Cytotoxicity in Volunteers
Authors: Yeager Mark P. , Colacchio Thomas A. , Yu Cecelia T. , Hildebrandt Laurie , Howell Alexandra L. , Weiss Julie , Guyre Paul M. 
Published: November 2003

Background
Opioids are used by patients who have conditions ranging from the acute pain of surgery and chronic cancer pain to substance abuse. Despite their widespread use and considerable experimental data about them, little is known about how opioids may alter in vivo immunity in humans. This study was designed to evaluate the in vivo effect of morphine on human peripheral blood immune functions.

Methods
Healthy volunteers underwent continuous exposure to morphine for 36 h including a 24-h intravenous infusion in the hospital. Peripheral blood was drawn for immune function studies at five measurement times before, during, and after morphine exposure. Peripheral blood mononuclear cells were tested for acute and gamma-interferon-stimulated natural killer cell cytotoxicity (NKCC), antibody-dependent cell cytotoxicity, antibody Fc receptor expression, and human immunodeficiency virus infectivity.

Results
Significant suppression of NKCC was observed at 2 and 24 h after the onset of intravenous morphine exposure. Suppression of NKCC persisted for 24 h after termination of morphine infusion in a "high"-dose study group. gamma-Interferon-stimulated NKCC and antibody-dependent cell cytotoxicity were also decreased after 24 h of intravenous morphine exposure. No effect on Fc receptor expression was observed. Mean virus antigen production after lymphocyte infection with human immunodeficiency virus was not increased (p24 100 ng/ml after morphine vs. 43 ng/ml before morphine; P = 0.17).

Conclusions
These results suggest that morphine administration, at doses within the range of analgesic use, can cause measurable suppression of some components of the human cellular immune system.
Combined Spinal-Epidural Anesthesia for Outpatient Surgery
Authors: Urmey William F. , Stanton Jennifer , Peterson Margaret , Sharrock Nigel E. 
Published: November 2003

Background
Combined spinal-epidural anesthesia (CSE) may offer theoretic advantages for outpatient surgery, because it produces the rapid onset of spinal anesthesia, with the option to extend the blockade with an epidural catheter. In this study, the authors attempted to determine an appropriate initial dose of a short-acting local anesthetic, 2% lidocaine, to administer for outpatient knee arthroscopy using CSE.

Methods
Data were collected from 90 patients undergoing outpatient knee arthroscopy. Using a double-blinded, prospective study design, patients were randomly assigned to receive CSE with an initial dose of intrathecal 2% lidocaine of 40, 60, or 80 mg. A 27-G 4 11/16-inch Whitacre needle was placed through a 17-G Weiss needle. Onset and regression of sensory anesthesia and motor blockade were measured by a blinded observer at frequent intervals.

Results
All 90 patients had adequate anesthesia. Durations of thoracic and lumbar sensory and lower limb motor blockade were significantly shorter in the 40-mg group compared with the 60- or 80-mg groups (P < 0.0002 Mantel-Cox, Survivorship Analysis). Indices of neural blockade resolved 30-40 min more rapidly in the 40-mg group than in either the 60- or 80-mg group. Times to urinate, site upright in a chair, take oral fluids, and be discharged were all significantly shorter (between 30 and 60 min) in the 40-mg group compared with the 60- and 80-mg groups (P < 0.01). Seven patients required intraoperative epidural supplementation: three in the 40-mg group, three in the 60-mg group, and one in the 80-mg group.

Conclusions
Combined spinal-epidural anesthesia with a 40-mg initial intrathecal dose of lidocaine provided reliable anesthesia for knee arthroscopy. Duration of spinal anesthesia with lidocaine was dose related.
Desflurane Inhibits Hypoxic Pulmonary Vasoconstriction in Isolated Rabbit Lungs
Authors: Loer Stephan A. , Scheeren Thomas W. L. , Tarnow Jorg 
Published: November 2003

Background
Inhalational anesthetics inhibit hypoxic pulmonary vasoconstriction (HPV) in vivo and in vitro with a half-maximum inhibiting effect (ED50) within concentrations applied for general anesthesia. Because it is unknown whether desflurane acts likewise, we studied its effect on HPV in isolated blood-perfused rabbit lungs and compared its ED50 with that of halothane.

Methods
Isolated blood-perfused rabbit lungs were randomly allocated to treatment with either desflurane (n = 6) or halothane (n = 6). HPV, defined as an increase in pulmonary arterial pressure (PAP) at constant flow, was elicited by decreasing inspiratory oxygen concentration from 20% to 3% for 4 min. This effect was determined without (control HPV) and with increasing concentrations of the anesthetics (fraction of inspired carbon dioxide kept constant at 4.8 +/- 0.2%, perfusate temperature at 37 degrees C, and blood flow at 100 ml.min-1).

Results
Before exposure to the anesthetics, PAP increased by 8.6 +/- 1.9 cmH2O for all lungs within 4 min of hypoxia (control PAP for all lungs 19.6 +/- 2.5 cmH2O). Desflurane decreased this effect in a concentration-dependent fashion with an ED50 of 14.5%, compared with that of halothane, with an ED50 of 1.7%.

Conclusions
Assuming that 1 minimum alveolar concentration (MAC) values of desflurane and halothane for rabbits are 8.9% and 1.39%, respectively, this study yields ED50 values for the inhibition of HPV of approximately 1.6 MAC for desflurane and 1.2 MAC for halothane (P not statistically significant).
Effect of Aminophylline on High-energy Phosphate Metabolism and Fatigue in the Diaphragm
Authors: Ide Tohru , Nichols David G. , Buck James R. , Eleff Scott M. , Shungu Dikoma C. , Robotham James L. , Fitzgerald Robert S. , Traystman Richard J. 
Published: November 2003

Background
Diaphragmatic fatigue causes respiratory failure, for which aminophylline has been used as therapy. Because the mechanism of action of aminophylline in reversing diaphragmatic fatigue is unclear, we used in vivo 31P magnetic resonance spectroscopy (MRS) to determine the relation between diaphragmatic activation, force output, and aerobic metabolism.

Methods
Bilateral phrenic stimulation was used to pace the diaphragm in pentobarbital-anesthetized piglets (6-10 weeks old; n = 44). Esophageal and abdominal pressures were measured to calculate transdiaphragmatic pressure (Pdi) (Pdi = abdominal pressure-esophageal pressure) as an index of force output. Activation was determined by the amplitude of the compound action potential of the diaphragmatic electromyogram. Aerobic metabolism was assessed with a 31P MRS surface coil on the right hemidiaphragm with the animal in a 4.7-T magnet. The animals were divided into four groups based on aminophylline loading dose: saline, aminophylline 10 mg/kg (A10), aminophylline 20 mg/kg (A20), and aminophylline 40 mg/kg (A40). After aminophylline loading the diaphragm was paced for 25 min followed by a 10-min recovery.

Results
Aminophylline concentrations were 12.2 +/- 0.7, 21.9 +/- 2.4, and 44.9 +/- 3.6 mg/l in the A10, A20, and A40 groups, respectively. Compound action potential amplitude decreased in all groups by 30% after 25 min of pacing. Conversely, Pdi remained at 100 +/- 3% of the initial value after 5 min of pacing in the A40 group but decreased to 75 +/- 3% in the saline group. Pdi recovered completely (103 +/- 17%) in the A40 group but remained depressed (72 +/- 6%) in the saline group. Pdi values were intermediate in the A10 and A20 groups. MRS data revealed inadequate energy supply/demand ratio in the saline group such that the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) increased to 1.01 +/- 0.09 after 5 min of pacing. Pi/PCr remained unchanged in the A40 group and was intermediate in the A10 and A20 groups. beta-Adenosine triphosphate and intracellular pH did not differ among groups or as a function of pacing. Diaphragmatic blood flow increased from a resting value of 35-60 to 300-410 ml.min-1 x 100 g-1 during pacing in all groups and was not affected by aminophylline dose.

Conclusions
Aminophylline, in a dose-dependent fashion, delays the onset of fatigue and improves recovery from fatigue. Delayed fatigue is associated with improved aerobic metabolism as reflected in a low Pi/PCr ratio.
Direct Cerebrovasodilatory Effects of Halothane, Isoflurane, and Desflurane during Propofol-induced Isoelectric Electroencephalogram in Humans
Authors: Matta Basil F. , Mayberg Teresa S. , Lam Arthur M. 
Published: November 2003

Abstract

Background
The effect of volatile anesthetics on cerebral blood flow depends on the balance between the agent's direct vasodilatory action and the indirect vasoconstrictive action mediated by flow-metabolism coupling. To compare the intrinsic action of volatile anesthetics, the effect of halothane, isoflurane, and desflurane on flow velocity in the middle cerebral artery during propofol-induced isoelectricity of the electroencephalogram was examined.
Desflurane and Isoflurane Exert Modest Beneficial Actions on Left Ventricular Diastolic Function during Myocardial Ischemia in Dogs
Authors: Pagel Paul S. , Hettrick Douglas A. , Lowe Dermot , Tessmer John P. , Warltier David C. 
Published: November 2003

Abstract

Background
Volatile anesthetics exert cardioprotective effects during myocardial ischemia. This investigation examined the regional systolic and diastolic mechanical responses to brief left anterior descending coronary artery (LAD) occlusion in the central ischemic zone and in remote normal myocardium in the conscious state and during desflurane and isoflurane anesthesia.
Further Characterization of the Receptor Mechanism Involved in the Antidysrhythmic Effect of Dexmedetomidine on Halothane/Epinephrine Dysrhythmias in Dogs
Authors: Kamibayashi Takahiko , Mammoto Tadanori , Hayashi Yukio , Yamatodani Atsushi , Takada Koji , Sasaki Shigeta , Yoshiya Ikuto 
Published: November 2003

Abstract

Background
alpha2Adrenoceptors in the central nervous system mediate various physiologic processes, including cardiovascular control. Recently, some of these actions have been reported to be mediated by a nonadrenergic receptor, namely an imidazoline receptor. The authors previously reported that dexmedetomidine, a selective alpha2agonist, prevents the genesis of halothane-epinephrine dysrhythmias through a central mechanism. Because dexmedetomidine also binds to imidazoline receptors, we performed the current study to examine the precise receptor mechanism involved in the antidysrhythmic property of dexmedetomidine.
Technique for Quantifying the Duration of Intravenous Anesthetic Effect
Authors: Bailey James M. 
Published: November 2003

Abstract

Background
Several recent studies have analyzed the relationship between pharmacokinetic parameters and the rate of decrease in concentration after discontinuation of a continuous drug infusion. Although these studies have clarified our understanding of those aspects of pharmacokinetics most relevant to anesthesia practice, they do not directly address the issue of the duration of drug effect, which will be a function of both pharmacokinetic and pharmacodynamic variables. This paper extends these concepts by presenting a method to unify pharmacokinetics and pharmacodynamics in a measure of duration of drug effect that is applicable when the drug effect is assessed in a binary, response/no response fashion.
Nitroprusside Inhibition of Platelet Function Is Transient and Reversible by Catecholamine Priming
Authors: Harris Stephen N. , Rinder Christine S. , Rinder Henry M. , Tracey Jayne B. , Smith Brian R. , Hines Roberta 
Published: November 2003

Abstract

Background
The time course and reversibility of sodium nitroprusside's in vivo inhibition of platelet function are unclear.
Inhaled Nitric Oxide Reduces Pulmonary Transvascular Albumin Flux in Patients with Acute Lung Injury
Authors: Benzing A. , Brautigam P. , Geiger K. , Loop T. , Beyer U. , Moser E. 
Published: November 2003

Abstract

Background
In acute lung injury, when pulmonary microvascular permeability is enhanced, transvascular fluid filtration mainly depends on pulmonary capillary pressure. Inhaled nitric oxide has been shown to decrease pulmonary capillary pressure. Therefore, the effect of inhaled nitric oxide at a concentration of 40 ppm on pulmonary transvascular albumin flux was studied in nine patients with acute lung injury.
Desflurane Reduces the Gain of Thermoregulatory Arteriovenous Shunt Vasoconstriction in Humans
Authors: Kurz Andrea , Xiong Junyu , Sessler Daniel I. , Dechert Martha , Noyes Katherine , Belani Kumar 
Published: November 2003

Abstract

Background
Thermoregulatory responses, such as arteriovenous shunt vasoconstriction, provide substantial protection against core hypothermia. A response can be characterized by its threshold (core temperature triggering response), gain (rate at which response intensity increases, once triggered), and maximum response intensity. Reduced gain decreases the efficacy of a thermoregulatory response at a given threshold because response intensity will increase more slowly than usual. The effects of general anesthesia on the gain of arteriovenous shunt vasoconstriction have not been reported. Accordingly, we tested the hypothesis that desflurane decreases the gain of centrally mediated vasoconstriction.
Halothane Modulates Thermosensitive Hypothalamic Neurons in Rat Brain Slices
Authors: Farber Neil E. , Schmidt Jeffrey E. , Kampine John P. , Schmeling William T. 
Published: November 2003

Abstract

Background
In vivo, halothane alters spontaneous firing in and thermosensitivity of neurons in the preoptic region of the anterior hypothalamus. To better understand the mechanisms by which halothane specifically disrupts normal thermoregulation, this investigation examined the effects of halothane on thermosensitive preoptic region neurons in isolated hypothalamic tissue slices.
Hemodynamic Responses to Intravascular Injection of Epinephrine-containing Epidural Test Doses in Adults during General Anesthesia
Authors: Liu Spencer S. , Carpenter Randall L. 
Published: November 2003

Background
Epidural anesthesia is sometimes initiated during general anesthesia, yet few data exist concerning efficacy of epinephrine-containing test doses.

Methods
Thirty-six patients were randomized to receive either 0.5 MAC isoflurane, 1 MAC isoflurane, or 0.5 MAC each (1 MAC total) of isoflurane and nitrous oxide. Each subject received intravenous saline followed by three test doses containing 45 mg lidocaine with 7.5, 15, and 30 micrograms epinephrine in a randomized, double-blind fashion. Heart rate and systolic, diastolic, and mean blood pressures were measured for 5 min after injection. Positive hemodynamic criteria identifying intravascular injection were determined from peak increases in hemodynamics during administration of saline. Dose-effect relationships between epinephrine and peak increases in hemodynamics were assessed with linear regression. Minimum required doses of epinephrine to produce peak positive hemodynamic increases on average were determined from linear regression.

Results
Positive hemodynamic criteria were identified as increases in heart rate > or = 8 beats/min, systolic blood pressure > or = 13 mmHg, diastolic blood pressure > or = 7 mmHg, and mean blood pressure > or = 9 mmHg. Significant dose-effect relationships were observed for epinephrine and peak increases in hemodynamics (correlation coefficients ranged from 0.61-0.91). Minimum required doses of epinephrine ranged from 6 to 19 micrograms depending on hemodynamic measurement and anesthetic group.

Conclusions
Hemodynamic responses to intravascular injection of test doses vary with dose of epinephrine and depth and type of general anesthetic used. Thus, the 15 micrograms epinephrine contained in the standard test dose may not be sufficient during all anesthetic conditions.