bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hemodynamic and Metabolic Manifestations of Acute Endotoxin Infusion in Pigs with and without the Malignant Hyperthermia Mutation
Authors: Musley Shailesh Kumar V. , Beebe David S. , Komanduri Vijaya , Iaizzo Paul A. , Belani Kumar G. 
Published: November 2003

Background
The hypermetabolic state induced by acute endotoxemia and malignant hyperthermia (MH) may be indistinguishable. The aims of this study were (1) to investigate the differences between MH and sepsis, (2) to determine whether acute endotoxemia can trigger MH, and (3) to establish the effects of dantrolene in these two disorders.

Methods
Three groups of swine were studied. All pigs were invasively monitored and initially anesthetized with nontriggering agents. A placebo MH-susceptible group (n = 5) received normal saline whereas the endotoxin groups (MH-susceptible, n = 6; MH-negative, n = 4) received intravenous endotoxin (250 microg/kg total) during 2.5 h. Halothane (1.5%) and succinylcholine (2-4 mg/kg) were then administered, followed by two doses of dantrolene (4 mg/kg total).

Results
Endotoxin infusion resulted in pulmonary hypertension and systemic hypotension in pigs with and without the MH mutation, but did not trigger MH. Halothane and succinylcholine triggered MH, evidenced by a markedly higher oxygen consumption in the MH-susceptible pigs that received endotoxin (325+/-196 ml/min) and those that did not (374+/-110 ml/min) compared to the MH-negative pigs (69+/-15 ml/min, P<0.0009), as well as muscular rigidity in the susceptible animals. Dantrolene reversed these changes. Three of the six MH-susceptible pigs that received endotoxin died; two died soon after triggering and one after dantrolene administration. In contrast, none of the MH-negative pigs or the MH-susceptible pigs that did not receive endotoxin died (0 of 9 vs. 3 of 6, P = 0.044).

Conclusion
Endotoxemia does not trigger MH, but may worsen outcome if it occurs.
Is Combined Spinal–Epidural Analgesia Associated with More Rapid Cervical Dilation in Nulliparous Patients When Compared with Conventional Epidural Analgesia?
Authors: Tsen Lawrence C. , Thue Brad , Datta Sanjay , Segal Scott 
Published: November 2003

Background
The combined spinal-epidural technique provides rapid onset of labor analgesia and, anecdotally, is associated with labors of shorter duration. Epidural analgesia, by contrast, has been suggested to prolong labor modestly. It is unclear, however, whether more rapid cervical dilation in patients who receive combined spinal-epidural analgesia is a physiologic effect of the technique or an artifact of patient selection. The authors hypothesized that anesthetic technique may influence the rate of cervical dilation, and we compared the effects of combined spinalepidural with those of epidural analgesia on the rate of cervical dilation.

Methods
One hundred healthy nulliparous parturients in spontaneous labor with singleton, vertex, full-term fetuses were enrolled in a double-blinded manner when their cervical dilation was less than 5 cm. The patients were randomly assigned to receive analgesia via a standardized combined spinal-epidural (n = 50) or epidural (n = 50) technique. Data were collected on cervical dilation, pain, sensory level, and motor blockade.

Results
When regional analgesia was induced in comparable groups at a mean of 3 cm cervical dilation, the mean initial cervical dilation rates were significantly faster in the combined spinal-epidural group (mean values, 2.1 +/- 2.1 cm/h vs. 1 +/- 1 cm/h; P = 0.0008). Five parturients in the combined spinal-epidural group had a very rapid (> 5 cm/h) rate of mean initial cervical dilation, compared with none of the women in the epidural group. Overall mean cervical dilation rates in patients who achieved full cervical dilation were 2.3 +/- 2.6 cm/h and 1.3 +/- 0.71 cm/h (P = 0.0154) in the combined spinal-epidural and epidural groups, respectively.

Conclusions
In healthy nulliparous parturients in early labor, combined spinal-epidural analgesia is associated with more rapid cervical dilation compared with epidural analgesia. Further study is needed to elicit the cause and overall effect of this difference.
Pharmacokinetics and Pharmacodynamics of Vecuronium in Rats with Systemic Inflammatory Response Syndrome
Authors: Blobner Manfred , Kochs Eberhard , Fink Heidrun , Mayer Barbara , Veihelmann Andreas , Brill Thomas , Stadler Josef 
Published: November 2003

Background
Insufficient detoxification caused by nitric oxide-related inhibition of cytochrome P450 may be important for metabolism of numerous drugs, including vecuronium. The present study investigated the pharmacodynamics and pharmacokinetics of vecuronium in rats with inflammatory liver dysfunction.

Methods
Male Sprague-Dawley rats (n = 56) were randomly allocated into two groups: In the sepsis group, liver inflammation was established by injection of 56 mg/kg heat-killed Corynebacterium parvum; control rats received the solvent. At day 4, groups were subdivided according to treatment with the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (250 mg/kg) or placebo. The aminopyrine breath test was performed to assess cytochrome P450 activity. Rats were anesthetized with propofol and mechanically ventilated. Duration of action of vecuronium (1.2 mg/kg) was measured by evoked mechanomyography (stimulation of the sciatic nerve, contraction of the gastrocnemius muscle). In seven rats of each subgroup a 50% neuromuscular blockade was established by a continuous vecuronium infusion. Vecuronium plasma levels were measured and plasma clearance of vecuronium was calculated. Nitric oxide synthesis was assessed by measuring nitrite/nitrate serum levels.

Results
In sepsis/placebo rats, vecuronium-induced neuromuscular blockade was prolonged (144% of contro/placebo), vecuronium plasma levels at 50% neuromuscular blockade were increased (122% of control/placebo), and plasma clearance was decreased (68% of control/placebo). N(G)-monomethyl-L-arginine therapy in rats with sepsis improved cytochrome P450 activity and plasma clearance of vecuronium, shortened duration of action of vecuronium, but did not alter the elevated vecuronium plasma levels.

Conclusions
A systemic inflammatory response syndrome with liver dysfunction results in decreased sensitivity to and a decreased elimination of vecuronium. Modulation of nitric oxide synthesis may be a strategy that can be used in the future to improve xenobiotic metabolism in sepsis.
Quantitative and Qualitative Effects of Isoflurane on Movement Occurring after Noxious Stimulation
Authors: Antognini Joseph F. , Wang Xiao Wei , Carstens E. 
Published: November 2003

Background
Anesthetic potency is assessed by determination of the anesthetic concentration that prevents gross, purposeful movement in response to noxious stimulation. It is unclear whether anesthetics cause a progressive decrease in the number and force of limb movements evoked by noxious stimulation, or a step decrease (consistent with an all-or-none effect at the site of action). The authors hypothesized that isoflurane and halothane would progressively depress the movement response.

Methods
Isoflurane minimum alveolar concentration (MAC) was determined in rats (N = 14) using a clamp applied to a hind paw. Lateral head movements and flexions of the forelimbs and hindlimbs were measured with force transducers. Isoflurane was adjusted to 0.6, 0.9, 1.1, and 1.4 MAC, the noxious stimulus applied, and the force and number of limb and head movements determined. Force and movement determinations were made in seven additional halothane-anesthetized rats.

Results
Isoflurane MAC was 1.3 +/- 0.1%. In general, if movement occurred after application of the noxious clamp, the head and all limbs were involved. At 0.6 MAC, the median number of extremity and head movements was 3.5 (10th-90th percentile, 2.0-11.4) with force generated per movement (force/movement) = 6.4 (2.0-13.2) N-s. Movement number decreased to 2.1 (0.25-4.2) at 0.9 MAC (P < 0.05), but force/movement was unchanged at 4.5 (0.4-15.1) N-s (Newton-second). At 1.1 MAC, movement number and force/movement decreased to 0.2 (0.0-1.5) and 0.1 (0.0-3.2) N-s, respectively (P < 0.005). No significant movement occurred at 1.4 MAC. The halothane-anesthetized rats had similar findings, although at 0.6 MAC they generated more movements (10.5 [5.2-19.8]) than the rats receiving isoflurane (P < 0.05).

Conclusions
The results indicate that increasing anesthetic concentration from 0.6 to 0.9 MAC had little effect on the motor system controlling the force of limb movements, and the neural system generating repeated limb movements was depressed, consistent with a differential anesthetic effect at separate sites.
Inhibitory Effects of Propofol on Acetylcholine-induced, Endothelium-dependent Relaxation and Prostacyclin Synthesis in Rabbit Mesenteric Resistance Arteries
Authors: Yamashita Akiko , Kajikuri Junko , Ohashi Masuo , Kanmura Yuichi , Itoh Takeo 
Published: November 2003

Background
Propofol (2,6-diisopropylphenol) modulates endothelium-dependent relaxation in some arterial preparations. The effect of propofol on endothelium-dependent, prostacyclin-mediated responses in mesenteric resistance arteries has not yet been clarified.

Methods
The effect of propofol was examined on acetylcholine-induced membrane potential changes in the presence of N(G)-nitro-L-arginine (L-NOARG) in endothelium-intact rabbit mesenteric resistance arteries in vitro. The effects of propofol were also examined on the endothelium-dependent relaxation and prostacyclin synthesis that was induced by acetylcholine in the presence of L-NOARG and nicardipine. The effect of propofol on the relaxation induced by a prostacyclin analogue was examined in strips treated with L-NOARG and diclofenac.

Results
Acetylcholine produced an initial and a slow membrane hyperpolarization. Propofol, 10 microM, and diclofenac each inhibited the acetylcholine-induced slow hyperpolarization, but not the initial hyperpolarization. Acetylcholine produced an endothelium-dependent relaxation that was significantly inhibited by propofol, 10 microM, and diclofenac. Propofol, 10 microM, greatly inhibited the acetylcholine-induced synthesis of prostacyclin, as did diclofenac. Propofol, 10 microM, had no effect on the relaxation induced by a prostacyclin analog.

Conclusions
In rabbit mesenteric resistance arteries, propofol inhibits the synthesis of prostacyclin and thus attenuates acetylcholine-induced, endothelium-dependent responses. Our results may help to explain why some actions seen with propofol in some preparations (e.g., vasoconstriction) are not seen after the endothelium is removed.
Supplemental Oxygen Reduces the Incidence of Postoperative Nausea and Vomiting
Authors: Greif Robert , Laciny Sonja , Rapf Brigitta , Hickle Randy S. , Sessler Daniel I. 
Published: November 2003

Background
Despite new anesthetic drugs and antiemetics, particularly 5-hydroxytryptamines, the incidence of postoperative nausea or vomiting remains between 20% and 70%. The authors tested the hypothesis that supplemental perioperative oxygen administration reduces the incidence of postoperative nausea or vomiting.

Methods
Patients undergoing colon resection were anesthetized with fentanyl and isoflurane. During and for 2 h after surgery they were randomly assigned to (1) 30% oxygen, balance nitrogen (n = 119); or (2) 80% oxygen, balance nitrogen (n = 112). The incidence of nausea or vomiting during the first 24 postoperative hours was evaluated by nurses blinded to group assignment and oxygen concentration. Data were analyzed with unpaired t or Mann-Whitney U tests. Results are presented as means +/- SD; P < 0.05 was considered significant.

Results
Factors known to influence nausea and vomiting were comparable in the two groups. Perioperative oxygen saturation was well within normal limits in each treatment group; saturations the first postoperative morning were comparable in each group. Supplemental oxygen reduced the incidence of postoperative nausea or vomiting from 30% in the patients given 30% oxygen to 17% in those given 80% oxygen (P = 0.027).

Conclusions
Supplemental oxygen reduced the incidence of postoperative nausea or vomiting nearly twofold after colorectal surgery. The mechanism by which oxygen administration reduces the incidence of these postoperative sequelae remains unknown but may be related to subtle intestinal ischemia. Because oxygen is inexpensive and essentially risk-free, supplemental oxygen appears to be an effective method of reducing postoperative nausea and vomiting.
Intramuscular Rapacuronium in Infants and Children
Authors: Reynolds Lynne M. , Infosino Andrew , Brown Ronald , Hsu James , Fisher Dennis M. 
Published: November 2003

Background
Intravenous rapacuronium's rapid onset and short duration suggest that intramuscular rapacuronium might facilitate tracheal intubation without prolonged paralysis. Accordingly, the authors injected rapacuronium into the deltoid muscle to determine the optimal dose and time for intubation in pediatric patients.

Methods
Unpremedicated patients (aged, 2 months to 3 yr) were studied. Part I: Spontaneous minute ventilation (V(E)) and twitch tension were measured during N2O/halothane anesthesia. Rapacuronium (2.2-5.5 mg/kg, given intramuscularly, n = 23), succinylcholine (4 mg/kg, given intramuscularly, n = 12), or vecuronium (0.1 mg/kg, given intravenously, n = 15) was given. Time to 50% depression of V(E) and 10% recovery of twitch were measured. Dose for each patient was changed 10-20% according to the previous patient's response. Part II: In 22 patients anesthetized with 0.82-1.0% halothane, the optimal rapacuronium dose determined in part I (infants, 2.8 mg/kg; children, 4.8 mg/kg) was given intramuscularly. Laryngoscopy was scored. Time to laryngoscopy was increased or decreased 0.5 min according to the previous patient's response.

Results
Part I: Rapacuronium typically depressed ventilation in < or = 2 min with 10% twitch recovery in 20-60 min. With succinylcholine, median time to ventilatory depression was 1.3 and 1.1 min for infants and children, respectively; for vecuronium, 0.7 and 0.6 min. Part I: Intubating conditions were good-excellent at 3.0 and 2.5 min in infants and children, respectively; time to 10% twitch recovery (mean +/- SD) was 31 +/- 14 and 36 +/- 14 min in the two groups.

Conclusions
This pilot study indicates that deltoid injection of rapacuronium, 2.8 mg/kg in infants and 4.8 mg/kg in children, permits tracheal intubation within 2.5-3.0 min, despite a light plane of anesthesia. Duration of action is intermediate.
Intrathecal Neostigmine and Sufentanil for Early Labor Analgesia
Authors: Nelson Kenneth E. , D'Angelo Robert , Foss Michael L. , Meister Greg C. , Hood David D. , Eisenach James C. 
Published: November 2003

Background
Recent efforts to improve the combined spinal epidural (CSE) technique have focused on adding opioids to other classes of analgesics. In this study, the authors used intrathecal neostigmine in combination with intrathecal sufentanil to investigate the usefulness of neostigmine for reducing side effects and prolonging the duration of sufentanil.

Methods
One hundred six healthy pregnant women in labor were enrolled in this study, which was divided into four phases. In all phases, patients received a CSE anesthetic while in the lateral position. In phase I, three groups of six women each received intrathecal neostigmine, 5, 10, or 20 microg, in an open-label, dose-escalating safety assessment. In phase II, 24 women received intrathecal sufentanil alone to establish an ED50 (dose that produces > 60 min of labor analgesia in 50% of patients). In phase III, an ED50 was established for sufentanil combined with a fixed dose of neostigmine (10 microg). In phase IV, 40 women received either twice the ED50 of sufentanil alone or twice the ED50 of sufentanil plus neostigmine, 10 microg.

Results
Neostigmine alone had no adverse effects on maternal vital signs, fetal heart rate, or Apgar scores. Neostigmine, 20 microg, produced analgesia in one patient and severe nausea and vomiting in another. The ED50 for intrathecal sufentanil alone was 4.1 +/- 0.31 microg, and the ED50 for intrathecal sufentanil combined with neostigmine, 10 microg, was 3.0 +/- 0.28 microg. The duration of analgesia and side effects from double these ED50s (sufentanil, 9 microg, or sufentanil, 6 microg, plus neostigmine, 10 microg) were similar between groups.

Conclusions
The 10-microg intrathecal neostigmine dose alone produced no analgesia or side effects, but reduced the ED50 of intrathecal sufentanil by approximately 25%. Additionally, doses approximately double these ED50s each produced a similar duration of analgesia and side effects, indicating intrathecal neostigmine shifts the dose-response curve for intrathecal sufentanil to the left.
Amsorb
Authors: Murray James M. , Renfrew Craig W. , Bedi Amit , McCrystal Conor B. , Jones David S. , Fee Howard J. P. 
Published: November 2003

Background
This article describes a carbon dioxide absorbent for use in anesthesia. The absorbent consists of calcium hydroxide with a compatible humectant, namely, calcium chloride. The absorbent mixture does not contain sodium or potassium hydroxide but includes two setting agents (calcium sulphate and polyvinylpyrrolidine) to improve hardness and porosity.

Methods
The resultant mixture was formulated and subjected to standardized tests for hardness, porosity, and carbon dioxide absorption. Additionally, the new absorbent was exposed in vitro to sevoflurane, desflurane, isoflurane, and enflurane to determine whether these anesthetics were degraded to either compound A or carbon monoxide. The performance data and inertness of the absorbent were compared with two currently available brands of soda lime: Intersorb (Intersurgical Ltd., Berkshire, United Kingdom) and Dragersorb (Drager, Lubeck, Germany).

Results
The new carbon dioxide absorbent conformed to United States Pharmacopeia specifications in terms of carbon dioxide absorption, granule hardness, and porosity. When the new material was exposed to sevoflurane (2%) in oxygen at a flow rate of 1 l/min, concentrations of compound A did not increase above those found in the parent drug (1.3-3.3 ppm). In the same experiment, mean +/-SD concentrations of compound A (32.5 +/- 4.5 ppm) were observed when both traditional brands of soda lime were used. After dehydration of the traditional soda limes, immediate exposure to desflurane (60%), enflurane (2%), and isoflurane (2%) produced concentrations of carbon monoxide of 600.0 +/- 10.0 ppm, 580.0 +/- 9.8 ppm, and 620.0 +/-10.1 ppm, respectively. In contrast, concentrations of carbon monoxide were negligible (1-3 ppm) when the anhydrous new absorbent was exposed to the same anesthetics.

Conclusions
The new material is an effective carbon dioxide absorbent and is chemically unreactive with sevoflurane, enflurane, isoflurane, and desflurane.
Human Neuronal Nicotinic Acetylcholine Receptors Expressed in Xenopus Oocytes Predict Efficacy of Halogenated Compounds That Disobey the Meyer-Overton Rule
Authors: Cardoso Rita A. , Yamakura Tomohiro , Brozowski Susan J. , Chavez-Noriega Laura E. , Harris Adron R. 
Published: November 2003

Background
According to the Meyer-Overton rule, anesthetic potency of a substance can be predicted by its lipid solubility, but a group of halogenated volatile compounds predicted to induce anesthesia does not obey this rule. Thus, these compounds are useful tools for studies of molecular targets of anesthetics. Human neuronal nicotinic acetylcholine receptor (hnAChR) subunits have been recently cloned, which allowed the authors to assess whether these receptors could differentiate among volatile anesthetic and nonimmobilizer compounds. This study provides the first data regarding anesthetic sensitivity of hnAChRs.

Methods
alpha2beta4, alpha3beta4, and alphaabeta2 hnAChRs were expressed in Xenopus oocytes, and effects of volatile anesthetics isoflurane and F3 (1-chioro-1,2,2-triflurocyclobutane, 1A) and nonimmobilizers F6 (1,2-dichlorohexafluorocyclobutane, 2N) and F8 (2,3-dichlorooctafluorobutane) on the peak acetylcholine-gated currents were studied using the two-electrode voltage-clamp technique.

Results
Isoflurane and F3 inhibited all the hnAChRs tested in a concentration-dependent manner. Isoflurane at a concentration corresponding to 1 minimum alveolar concentration (MAC) inhibited 83, 69, and 71% of ACh-induced currents in alpha2beta4, alpha3beta4, and alpha4beta2 hnAChRs, respectively, and 1 MAC of F3 inhibited 64, 44, and 61% of currents gated in those receptors. F6 (8-34 microM) did not cause any changes in currents gated by any of the receptors tested. F8 (4-18 microM) did not alter the currents gated in either alpha3beta4 or alpha4beta2 receptors, but caused a small potentiation of alpha2beta4 hnAChRs without a concentration-response relation.

Conclusion
The in vivo potency and effectiveness of volatile anesthetic and nonimmobilizer compounds were consistent with their actions on hnAChRs expressed in a recombinant expression system, suggesting a potential participation of these receptors in the mechanisms of anesthesia.
Forecasting Surgical Groups’ Total Hours of Elective Cases for Allocation of Block Time
Authors: Dexter Franklin , Macario Alex , Qian Fang , Traub Rodney D. 
Published: November 2003

Background
Allocation of the correct amount of operating room (OR) "block time" can provide surgeons with access to sufficient OR time to complete their elective cases while optimally matching staffing with the elective case workload (to maximize labor productivity). To evaluate how to predict accurately total hours of elective cases performed by a surgical group using data from surgical services information systems, the authors addressed the following questions: (1) How many previous 4-week periods of data should be used to minimize error in forecasting a surgical group's total hours of elective cases? (2) Using the number of 4-week periods from question #1, can we detect trends or correlations between successive periods that could be used to improve forecasting accuracy? (3) How can results from questions #1 and #2 be used to calculate an upper prediction bound (upper limit) for the total hours of elective cases that will be completed in a future period? Prediction bounds can be used to budget staffing accurately.

Methods
Time series analysis was performed on total hours of elective cases over 39 consecutive 4-week periods from 17 surgical groups.

Results
The average of 12 consecutive periods' total hours of elective cases had an appropriate error profile. The observations within each series of 12 consecutive 4-week periods followed a normal distribution, with each observation of total hours of elective cases not correlated with the subsequent observation.

Conclusions
The average of the most recent 12 4-week periods can be used to predict surgical groups' future use of block time.