bluuebunny/crossref_metadata_2025 huggingface dataset:
Perflubron Emulsion Delays Blood Transfusions in Orthopedic Surgery
Authors: Spahn Donat R. , van Brempt Ronald , Theilmeier Gregor , Reibold Jan-Peter , Welte Martin , Heinzerling Hartmut , Birck Katrin M. , Keipert Peter E. , Messmer Konrad
Published: November 2003

Background

Fluorocarbon emulsions have been proposed as temporary artificial oxygen carriers. The aim of the present study is to compare the effectiveness of perflubron emulsion with the effectiveness of autologous blood or colloid infusion for reversal of physiologic transfusion triggers.

Methods

A multinational, multicenter, randomized, controlled, single-blind, parallel group study was performed in 147 orthopedic patients. Patients underwent acute normovolemic hemodilution with colloid to a target hemoglobin of 9 g/dl with an inspiratory oxygen fraction (FIO2) of 0.40. Patients were then randomized into one of four treatment groups after having reached any of the protocol-defined transfusion triggers including tachycardia (heart rate > 125% of posthemodilution rate or > 110 bpm), hypotension (mean arterial pressure < 75% of posthemodilution level or < or = 60 mmHg), elevated cardiac output (> 150% of posthemodilution level) or decreased mixed venous oxygen partial pressure (PVO2; < 38 mmHg). Treatments in the four groups were 450 ml autologous blood harvested during acute normovolemic hemodilution given at FO2 = 0.40; 450 ml colloid at FIO2 = 1.0; 0.9 g/kg perflubron emulsion with colloid (total = 450 ml) at FIO2 = 1.0; and 1.8 g/kg perflubron emulsion with colloid (total = 450 ml) at FIO2 = 1.0. The primary endpoint was duration of transfusion-trigger reversal. A secondary end-point was percentage of transfusion-trigger reversal.

Results

Perflubron emulsion was well tolerated with no serious adverse event attributed to drug treatment. Duration of reversal was longest in the 1.8 g/kg perflubron group (median, 80 min; 95% confidence interval, 60-100 min; P = 0.014 vs. autologous blood, P < 0.001 vs. colloid) followed by the 0.9 g/kg perflubron group (median, 59 min; 95% confidence interval, 40-90 min), the autologous blood group (median, 55 min; 95% confidence interval, 30-70 min) and the colloid group (median, 30 min; 95% confidence interval, 27-60 min). Percentage of reversal was also highest in the 1.8 g/kg perflubron group (97%; P < 0.001 vs. autologous blood; P = 0.014 vs. colloid), followed by 0.9 g/kg perflubron (82%), colloid (76%), and autologous blood (60%).

Conclusions

Perflubron emulsion (1.8 g/kg) combined with 100% oxygen ventilation is more effective than autologous blood or colloid infusion in reversing physiologic transfusion triggers.
Caudal Block in Children
Authors: Khalil Samia , Campos Carlos , Farag Adel M. , Vije Hadassah , Ritchey Michael , Chuang Alice
Published: November 2003

Background

Bupivacaine provides reliable, long-lasting anesthesia and analgesia when given via the caudal route. Ropivacaine is a newer, long-acting local anesthetic that (at a concentration providing similar pain relief) has less motor nerve blockade and may have less cardiotoxicity than bupivacaine.

Methods

In a double-blind trial, 81 healthy children, undergoing ambulatory surgical procedures, were randomly allocated to receive caudal analgesia with either bupivacaine or ropivacaine, 0.25%, 1 mVkg. All blocks were placed by an attending anesthesiologist or an anesthesia fellow after induction of general anesthesia.

Results

Data were available for 75 children. There were no significant differences between the two groups in baseline characteristics or in anesthesia, surgery, recovery room, or day surgery unit durations. The quality and duration of postoperative pain relief did not differ. Motor and sensory effects were similar. Time to first micturition did not differ.

Conclusion

Ropivacaine (0.25%, 1 ml/kg) provided adequate postoperative analgesia with no difference from bupivacaine (0.25%, 1 ml/kg) in quality and duration of pain relief, motor and sensory effects, or time to first micturition in our study children.
Effects of Dobutamine on Hemodynamics and Left Ventricular Performance after Cardiopulmonary Bypass in Cardiac Surgical Patients
Authors: Romson Joseph L. , Leung Jacqueline M. , Bellows Wayne H. , Bronstein Merrill , Keith Fraser , Moores William , Flachsbart Keith , Richter Richard , Pastor Darwin , Fisher Dennis M.
Published: November 2003

Background

Dobutamine is commonly used to improve ventricular performance after cardiopulmonary bypass. The authors determined the effect of dobutamine on hemodynamics and left ventricular performance immediately after cardiopulmonary bypass in patients undergoing coronary artery bypass graft surgery.

Methods

One hundred patients received sequential 3-min infusions of dobutamine at 0-40 microg x kg(-1) x min(-1) immediately after cardiopulmonary bypass. Ten additional patients who received no dobutamine served as controls. Hemodynamics and left ventricular performance (fractional area change by transesophageal echocardiography, stroke volume index, and thermodilution cardiac index) were measured. Mixed-effects modeling accounted for repeated-measures data and interindividual differences and allowed for potential effects of covariates.

Results

Heart rate increased in a dose-dependent manner. The slope of HR versus dobutamine dose was steeper in individuals in whom peak dobutamine dose was not reached compared with that in the remaining individuals; slope decreased 2.71 +/- 0.68% per year of age. Dobutamine affected blood pressure minimally, but slightly decreased pulmonary capillary wedge pressure and central venous pressure. Systemic vascular resistance initially increased with dobutamine 10 microg x kg(-1) x min(-1) and remained constant with larger doses. Dobutamine produced a dose-dependent increase in left ventricular performance, primarily by increasing heart rate, because stroke volume index decreased with dobutamine dose.

Conclusion

Our results suggest that the response to graded dobutamine infusion in the post-cardiopulmonary bypass period differs from that previously reported. After cardiopulmonary bypass, the dominant mechanism by which dobutamine improves left ventricular performance is by increasing heart rate. Dobutamine affects blood pressure minimally.
Cardioprotective Effects of Propofol and Sevoflurane in Ischemic and Reperfused Rat Hearts
Authors: Mathur Sanjiv , Farhangkhgoee Parviz , Karmazyn Morris
Published: November 2003

Background

Sodium ion-hydrogen ion (Na(+)-H(+)) exchange inhibitors are effective cardioprotective agents. The N(+)-H(+) exchange inhibitor HOE 642 (cariporide) has undergone clinical trials in acute coronary syndromes, including bypass surgery. Propofol and sevoflurane are also cardioprotective via unknown mechanisms. The authors investigated the interaction between propofol and HOE 642 in the ischemic reperfused rat heart and studied the role of adenosine triphosphate-sensitive potassium (K(ATP)) channels in the myocardial protection associated with propofol and sevoflurane.

Methods

Isolated rat hearts were perfused by the Langendorff method at a constant flow rate, and left ventricular function and coronary pressures were assessed using standard methods. Energy metabolites were also determined. To assess the role of K(ATP) channels, hearts were pretreated with the K(ATP) blocker glyburide (10 microM). Hearts were then exposed to either control buffer or buffer containing HOE 642 (5 microM), propofol (35 microM), sevoflurane (2.15 vol%), the K(ATP) opener pinacidil (1 microM), or the combination of propofol and HOE 642. Each heart was then subjected to 1 h of global ischemia followed by 1 h of reperfusion.

Results

Hearts treated with propofol, sevoflurane, pinacidil, or HOE 642 showed significantly higher recovery of left ventricular developed pressure and reduced end-diastolic pressures compared with controls. The combination of propofol and HOE 642 provided superior protection toward the end of the reperfusion period. Propofol, sevoflurane, and HOE 642 also attenuated the onset and magnitude of ischemic contracture and preserved high-energy phosphates (HEPs) compared with controls. Glyburide attenuated the cardioprotective effects of sevoflurane and abolished the protection observed with pinacidil. In contrast, glyburide had no effect on the cardioprotection associated with propofol treatment.

Conclusion

HOE 642, propofol, and sevoflurane provide cardioprotection via different mechanisms. These distinct mechanisms may allow for the additive and superior protection observed with the combination of these anesthetics and HOE 642.
Propofol Has Both Enhancing and Suppressing Effects on Human Platelet Aggregation In Vitro
Authors: Hirakata Hideo , Nakamura Kumi , Yokubol Bencharatana , Toda Hiroshi , Hatano Yoshio , Urabe Nobukata , Mori Kenjiro
Published: November 2003

Background

Volatile anesthetics are known to suppress platelet aggregation. In contrast, there is conflicting information regarding the effect of propofol on platelet function. The present study was designed to clarify the effects of propofol on platelet function and the mechanisms underlying these effects.

Methods

Propofol or an equivalent volume of 10% Intralipos (as a control) was added to test tubes 5 min before the induction of each reaction. Platelet aggregation induced by epinephrine, arachidonic acid (AA), prostaglandin G2 (PGG2), or STA2 (a thromboxane A2 [TXA2] analog) was measured using an eight-channel aggregometer. To determine type 1 cyclooxygenase activity, AA (0.5 mM) was added to an assay mixture containing type 1 cyclooxygenase, and the concentration of the final product, malonaldehyde, was measured by spectrophotometry. Epinephrine-, adenosine diphosphate-, AA-, and PGG2-induced TXA2 formation was measured using a commercially available radioimmunoassay kit. To estimate TXA2 receptor-binding affinity, 3H-S145, a specific TXA2 receptor antagonist, was added, and the radioactivity of receptor-bound 3H-S145 was determined using a liquid scintillation analyzer. Inositol 1,4,5-triphosphate formation was measured in STA2-stimulated platelets using a commercially available inositol 1,4,5-triphosphate assay kit.

Results

Propofol (40 microM) enhanced, whereas 100 microM suppressed, adenosine diphosphate- and epinephrine-induced secondary aggregation without affecting primary aggregation. Propofol (40 microM) also enhanced, but 100 microM suppressed, AA-induced aggregation. Propofol (100 microM) enhanced PGG2- and STA2-induced aggregation. Propofol (100 microM) suppressed AA-induced TXA2 formation but did not alter that induced by PGG2. Propofol (30-100 microM) suppressed AA-induced malonaldehyde formation, indicating inhibition of type 1 cyclooxygenase activity. Propofol did not alter TXA2 receptor-binding affinity. Propofol (30 and 100 microM) augmented inositol 1,4,5-triphosphate formation in STA2-stimulated platelets.

Conclusions

The present findings clearly indicate that high concentrations of propofol suppress the activity of type 1 cyclooxygenase, the enzyme that converts AA to PGG2. Furthermore, propofol also enhanced STA2-induced inositol 1,4,5-triphosphate formation. These results may explain the inconsistent findings of previous investigators.
Growth of Staphylococcus aureus in Diprivan and Intralipid
Authors: Langevin Paul B. , Gravenstein Nikolaus , Doyle Thomas J. , Roberts Steven A. , Skinner Stacy , Langevin Sharon O. , Gulig Paul A.
Published: November 2003

Background

The incidence and severity of infections are increased when Intralipid or Diprivan are administered to patients. Intralipid promotes infection, presumably by inhibiting the reticuloendothelial system, thereby suppressing the host's constitutive immunity, whereas Diprivan supposedly promotes infection by supporting bacterial growth and increasing the inoculating dose. This study considers whether bacterial replication alone in Intralipid and Diprivan adequately explains the increased risk of infection associated with these agents or whether other factors might also be involved.

Methods

Staphylococcus aureus was cultured in 10% Intralipid or Diprivan at clinically relevant conditions or in Intralipid containing 0.005% (w/v) sodium EDTA, a current additive, to measure growth. To determine whether Intralipid affected infection, New Zealand white rabbits were injected intravenously with S. aureus with or without Intralipid. Twenty-four hours later, bacteria in lung, liver, spleen, and kidney tissues were enumerated.

Results

S. aureus failed to grow in Diprivan or Intralipid containing 0.005% EDTA. Whereas S. aureus did replicate in plain Intralipid, growth was delayed until the bacteria conditioned the media. Once initiated, growth was slow at clinically relevant temperatures. The administration of Intralipid to rabbits significantly increased the recovery of staphylococci from the kidneys, P < 0.001, relative to the other tissues 24 h after an intravenous inoculation with S. aureus, compared with rabbits receiving S. aureus with no Intralipid.

Conclusions

These results suggest that Diprivan, and possibly Intralipid, represent poor media for the growth of S. aureus and may promote infection through mechanisms other than increased inoculum size.
Which Algorithm for Scheduling Add-on Elective Cases Maximizes Operating Room Utilization?
Authors: Dexter Franklin , Macario Alex , Traub Rodney D.
Published: November 2003

Background

The algorithm to schedule add-on elective cases that maximizes operating room (OR) suite utilization is unknown. The goal of this study was to use computer simulation to evaluate 10 scheduling algorithms described in the management sciences literature to determine their relative performance at scheduling as many hours of add-on elective cases as possible into open OR time.

Methods

From a surgical services information system for two separate surgical suites, the authors collected these data: (1) hours of open OR time available for add-on cases in each OR each day and (2) duration of each add-on case. These empirical data were used in computer simulations of case scheduling to compare algorithms appropriate for "variable-sized bin packing with bounded space." "Variable size" refers to differing amounts of open time in each "bin," or OR. The end point of the simulations was OR utilization (time an OR was used divided by the time the OR was available).

Results

Each day there were 0.24 +/- 0.11 and 0.28 +/- 0.23 simulated cases (mean +/- SD) scheduled to each OR in each of the two surgical suites. The algorithm that maximized OR utilization, Best Fit Descending with fuzzy constraints, achieved OR utilizations 4% larger than the algorithm with poorest performance.

Conclusions

We identified the algorithm for scheduling add-on elective cases that maximizes OR utilization for surgical suites that usually have zero or one add-on elective case in each OR. The ease of implementation of the algorithm, either manually or in an OR information system, needs to be studied.
Changes in Electroencephalogram and Autonomic Cardiovascular Activity during Induction of Anesthesia with Sevoflurane Compared with Halothane in Children
Authors: Constant Isabelle , Dubois Marie-Claude , Piat Véronique , Moutard Marie-Laure , McCue Maggie , Murat Isabelle
Published: November 2003

Background

This study was design to assess clinical agitation, electroencephalogram (EEG) and autonomic cardiovascular activity changes in children during induction of anesthesia with sevoflurane compared with halothane using noninvasive recording of EEG, heart rate, and finger blood pressure.

Methods

Children aged 2-12 yr premedicated with midazolam were randomly assigned to one of three induction techniques: 7% sevoflurane in 100% O2 (group SevoRAPID); 2%, 4%, 6%, and 7% sevoflurane in 100% O2 (group SevoINCR); or 1%, 2%, 3%, and 3.5% halothane in 50% N2O-50% O2 (group HaloN2O). An additional group of children who received 7% sevoflurane in 50% N2O-50% O2 (group SevoN2O) was enrolled after completion of the study. Induction was videotaped. EEG, heart rate, and finger blood pressure were continuously recorded during induction until 5 min after tracheal intubation and analyzed in frequency domain using spectral analysis.

Results

Agitation was more frequent when anesthesia was induced with 100% O2 compared to the mixture of oxygen and nitrous oxide. No seizures were recorded in any group. In the four groups, induction of anesthesia was associated with an increase in EEG total spectral power and a shift toward the low-frequency bands. Sharp slow waves were present on EEG tracings of the three sevoflurane groups, whereas slow waves and fast rhythms (spindles) were observed in the halothane group. Sevoflurane induced a greater withdrawal of parasympathetic activity than halothane and a transient relative increase in sympathetic vascular tone at loss of eyelash reflex.

Conclusions

Agitation observed during sevoflurane induction was not associated with seizures. Sevoflurane induction induced a marked inhibition of parasympathetic control of heart rate.
Effect of the Duration of Electrical Stimulation on the Analgesic Response in Patients with Low Back Pain
Authors: Hamza Mohamed A. , Ghoname El-sayed A. , White Paul F. , Craig William F. , Ahmed Hesham E. , Gajraj Noor M. , Vakharia Akshay S. , Noe Carl E.
Published: November 2003

Background

Electrical stimulation of peripheral nerves produces acute analgesic effects. This randomized, sham-controlled, crossover study was designed to evaluate the effect of differing durations of electrical stimulation on the analgesic response to percutaneous electrical nerve stimulation in 75 consenting patients with low back pain.

Methods

All patients received electrical stimulation for four different time intervals (0, 15, 30, and 45 min) in a random sequence over the course of an 11-week study period. All active percutaneous electrical nerve stimulation treatments were administered using alternating frequencies of 15 and 30 Hz three times per week for 2 consecutive weeks. The prestudy assessments included the health status survey short form questionnaire and 10-cm visual analog scale scores for pain, physical activity, and quality of sleep, with 0 being the best and 10 being the worst. The pain scoring was repeated 5-10 min after each 60-min study session and 24 h after the last treatment session with each of the four methods. The daily oral analgesic requirements were assessed during each of the four treatment blocks. At the end of each 2-week treatment block, the questionnaire was repeated.

Results

Electrical stimulation using percutaneously placed needles produced short-term improvements in the visual analog scale pain, physical activity, and quality of sleep scores, and a reduction in the oral analgesic requirements. The 30-min and 45-min durations of electrical stimulation produced similar hypoalgesic effects (48+/-21% and 46+/-19%, respectively) and were significantly more effective than either 15 min (21+/-17%) or 0 min (10+/-11%). The 30- and 45-min treatments were also more effective in improving physical activity and sleep scores over the course of the 2-week treatment period. In contrast to the sham treatment (0 min), the health status survey short form revealed that electrical stimulation for 15 to 45 min three times per week for 2 weeks improved patient function.

Conclusion

The recommended duration of electrical stimulation with percutaneous electrical nerve stimulation therapy is 30 min.
Experimental Pain Augments Experimental Dyspnea, but Not Vice Versa in Human Volunteers
Authors: Nishino Takashi , Shimoyama Naohito , Ide Tohru , Isono Shiroh
Published: November 2003

Background

Pain and dyspnea frequently coexist in many clinical situations. However, whether the two different symptoms interact with each other has not been elucidated. To elucidate the interaction between pain and dyspneic sensations, the authors investigated separately the effects of pain on dyspnea and the effects of dyspnea on pain in 15 healthy subjects.

Methods

Subjects were asked to rate their sensation of pain or dyspnea using a visual analog scale (VAS) during pain stimulation produced by tourniquet inflation (inflation cuff pressure: 350 mmHg) around the calf, and/or the respiratory loading consisted of a combination of resistive load (77 cm H2O x l(-1) x s(-1)) and hypercapnia induced by extra mechanical dead space (255 ml). In addition to changes in VAS scores, changes in ventilatory airflow and airway pressure were continuously measured.

Results

Pain stimulation and loaded breathing increased VAS scores, ventilation, and occlusion pressure (P0.1). The addition of a pain stimulus during loaded breathing increased the dyspneic VAS score (median 56 [interquartile range 50-62] vs. 64 [55-77]: before vs. after addition of pain stimulus, P < 0.05) with concomitant increases in minute ventilation (10.8 [10.1-13.3] vs. 12.4 [11.0-14.8] l/min, P < 0.05) and P0.1 (5.5 [4.9-7.2] vs. 6.8 [5.8-9.0] cm H2O, P < 0.05). The addition of respiratory loading during pain stimulation did not cause a significant change in pain VAS score (40 [33-55] vs. 31 [30-44]: before vs. after addition of respiratory loading), although both additional burdens increased further minute ventilation (10.0 [8.8-10.9] vs. 12.0 [10.6-13.2] l/min, P < 0.05) and P0.1 (2.5 [2.0-3.0] vs. 6.2 [4.9-7.0] cm H2O, P < 0.05).

Conclusion

The authors' findings suggest that pain intensifies the dyspneic sensation, presumably by increasing the respiratory drive, whereas dyspnea may not intensify the pain sensation.
Beneficial Effects from β-Adrenergic Blockade in Elderly Patients Undergoing Noncardiac Surgery
Authors: Zaugg Michael , Tagliente Thomas , Lucchinetti Eliana , Jacobs Ellis , Krol Marina , Bodian Carol , Reich David L. , Silverstein Jeffrey H.
Published: November 2003

Background

Perioperative beta-blockade has been shown to improve long-term cardiac outcome in noncardiac surgical patients. A possible mechanism for the reduced risk of perioperative myocardial infarction is the attenuation of the excitotoxic effects of catecholamine surges by beta-blockade. It was hypothesized that beta-blocker-induced alteration of the stress response was responsible for the reported improvements in cardiovascular outcome. Several variables associated with the perioperative use of beta-blockade were also evaluated.

Methods

Sixty-three patients were randomly assigned to one of three groups: group I, no atenolol; group II, pre- and postoperative atenolol; group III, intraoperative atenolol. Hormonal markers of the stress response (neuropeptide Y, epinephrine, norepinephrine, cortisol, and adrenocorticotropic hormone) were evaluated preoperatively and for 72 h after surgery.

Results

Perioperative beta-blockade did not significantly alter the hormonal stress response. However, the beta-blocked patients showed improved hemodynamic stability during emergence and postoperatively. They also received less fentanyl intraoperatively (27.7%, P < 0.0001), experienced faster early recovery, had lower pain scores, and required less analgesia in the postanesthesia care unit. Cardiac troponin I release was detected in 8 of 19, 4 of 20, and 5 of 20 patients in groups I, II, and III, respectively (not significant). Three patients in group I had cardiac troponin I levels consistent with myocardial infarction.

Conclusion

Beta-blockade does not reduce the neuroendocrine stress response, suggesting that this mechanism is not responsible for the previously reported improved cardiovascular outcome. However, it confers several advantages, including decreased analgesic requirements, faster recovery from anesthesia, and improved hemodynamic stability. The release of cardiac troponin I suggests the occurrence of perioperative myocardial damage in this elderly population, which appears to be independent of the neuroendocrine stress response.
Airway Injury during Anesthesia
Authors: Domino Karen B. , Posner Karen L. , Caplan Robert A. , Cheney Frederick W.
Published: November 2003

Background

Airway injury during general anesthesia is a significant source of morbidity for patients and a source of liability for anesthesiologists. To identify recurrent patterns of injury, the authors analyzed claims for airway injury in the American Society of Anesthesiologists (ASA) Closed Claims Project database.

Methods

The ASA Closed Claims database is a standardized collection of case summaries derived from professional liability insurance companies closed claims files. All claims for airway injury were reviewed in depth and were compared to other claims during general anesthesia.

Results

Approximately 6% (266) of 4,460 claims in the database were for airway injury. The most frequent sites of injury were the larynx (33%), pharynx (19%), and esophagus (18%). Injuries to the esophagus and trachea were more frequently associated with difficult intubation. Injuries to temporomandibular joint and the larynx were more frequently associated with nondifficult intubation. Injuries to the esophagus were more severe and resulted in a higher payment to the plaintiff than claims for other sites of airway injury. Difficult intubation (odds ratio = 4.53, 95% confidence interval [CI] = 2.36, 8.71), age older than 60 yr (odds ratio = 2.97, 95% CI = 1.51, 5.87), and female gender (odds ratio = 2.43, 95% CI = 1.09, 5.42) were associated with claims for pharyngoesophageal perforation. Early signs of perforation, e.g., pneumothorax and subcutaneous emphysema, were present in only 51% of perforation claims, whereas late sequelae, e.g., retropharyngeal abscess and mediastinitis, occurred in 65%.

Conclusion

Patients in whom tracheal intubation has been difficult should be observed for and told to watch for the development of symptoms and signs of retropharyngeal abscess, mediastinitis, or both.
Halothane and Isoflurane Increase Spontaneous but Reduce the N-methyl-D-aspartate–evoked Dopamine Release in Rat Striatal Slices
Authors: Keita Hawa , Henzel-Rouellé Danielle , Dupont Hervé , Desmonts Jean-Marie , Mantz Jean
Published: November 2003

Background

Experimental data suggest that volatile anesthetics induce significant changes in extracellular dopamine concentrations in the striatum, a restricted but functionally important brain area. In the present study, the authors used a superfused slice preparation to examine the effects of halothane and isoflurane on both spontaneous and N-methyl-D-aspartate (NMDA)-evoked dopamine release in the striatum, and whether these effects involved actions of these anesthetics mediated by gamma-aminobutyric acid receptors in this structure.

Methods

Radioactivity collected from 5-min fractions was compared in the absence (basal release) or presence (evoked release) of NMDA alone and combined with various pharmacologic or anesthetic agents in slices of the dorsolateral striatum and synaptosomes of the whole striatum preloaded with 3H-dopamine and superfused with artificial cerebrospinal fluid.

Results

In tetrodotoxin-treated striatal slices, halothane and isoflurane significantly increased dopamine basal release (EC50 = 0.33 mM and 0.41 mM for halothane and isoflurane, respectively). Both agents decreased the NMDA-evoked dopamine release in both the absence (IC50 = 0.15 mM and 0.14 mM for halothane and isoflurane, respectively) and presence (IC50 = 0.15 mM for both halothane and isoflurane) of tetrodotoxin in slices, and in synaptosomes (IC50 = 0.19 mM for both halothane and isoflurane). NMDA-induced dopamine release was significantly enhanced by bicuculline, a gamma-aminobutyric acid receptor antagonist. Halothane and isoflurane inhibitory effects on NMDA-evoked dopamine release were significantly reduced in the presence of bicuculline.

Conclusion

These results indicate that halothane and isoflurane decrease the NMDA-evoked dopamine release by acting directly at dopamine terminals in striatal slices. They support the involvement of both depression of presynaptic NMDA receptor-mediated responses and enhancement of gamma-aminobutyric acid receptor-mediated responses in these effects.
Influence of Age on Hypnotic Requirement, Bispectral Index, and 95% Spectral Edge Frequency Associated with Sedation Induced by Sevoflurane
Authors: Katoh Takasumi , Bito Hiromichi , Sato Shigehito
Published: November 2003

Background

Aging is associated with a reduction in anesthetic requirements. The effects of age on the electroencephalographic response to inhalational anesthesia have not been well documented. The objective of the present study was to determine the influence of age on hypnotic requirement and electroencephalographic derivatives such as bispectral index and 95% spectral edge frequency associated with sedation induced by sevoflurane.

Methods

Ninety-six patients were randomly allocated into one of three age groups A, B, and C, ranging in age from 18-39 yr, 40-64 yr, and 65-85 yr, respectively. Patients in each group were sedated with sevoflurane at two predetermined concentrations ranging between 0.45% and 0.85%. The relationship between sevoflurane concentration and response to a verbal command, as well as the relationships between response and bispectral index and 95% spectral edge frequency, was determined.

Results

Multiple regression analysis showed that end-tidal sevoflurane concentration and age significantly affected both bispectral index and 95% spectral edge frequency. ED50 values of sevoflurane concentration for loss of consciousness, defined as no response to verbal command, were different between groups A and C: 0.72 (95% confidence interval: 0.68-0.75) versus 0.59 (95% confidence interval: 0.56-0.62). However, the same effective values of bispectral index and 95% spectral edge frequency at this same clinical end point did not differ.

Conclusions

Increasing age reduced sevoflurane requirements to suppress responses to a verbal command but did not change bispectral index and 95% spectral edge frequency associated with this end point, and in a population with a wide age range, bispectral index would predict depth of sedation better than end-tidal sevoflurane concentration.
Effect of Epidural Blockade on Protein, Glucose, and Lipid Metabolism in the Fasted State and during Dextrose Infusion in Volunteers
Authors: Schricker Thomas , Klubien Kristine , Wykes Linda , Carli Franco
Published: November 2003

Background

To interpret correctly the results from studies performed during surgery and anesthesia it is necessary to dissect the separate effect of the anesthetic technique itself. The purpose of this study was to investigate the metabolic effects of epidural blockade (T7-S1) with bupivacaine 0.25% after 12 h fasting and during administration of 4 mg x kg(-1) x min(-1) dextrose in six healthy volunteers.

Methods

Each volunteer was assigned to randomly undergo a 6-h multiple stable isotope infusion study (3 h fasted, 3 h dextrose infusion) with or without epidural blockade. L-[1-13C]leucine, [6,6-2H2]glucose, and [1,1,2,3,3-2H5]glycerol were infused to measure protein synthesis, breakdown, and amino acid oxidation; glucose production and clearance; and lipolysis. Plasma concentrations of glucose, lactate, glycerol, free fatty acids, insulin, and glucagon were determined.

Results

Epidural blockade with bupivacaine had no influence on protein oxidation, breakdown and synthesis, glucose production, glucose clearance and lipolysis in the fasted state. Plasma concentrations of metabolic substrates and hormones also were not affected. Dextrose infusion significantly increased glucose clearance and plasma concentrations of glucose and insulin, while endogenous glucose production and lipolysis decreased to a similar degree in both groups. Protein synthesis, breakdown, and oxidation did not change during dextrose infusion.

Conclusions

Epidural blockade with bupivacaine in the absence of surgery has no effect on fasting protein, glucose, and lipid metabolism. Epidural blockade does not modify the inhibitory influence of dextrose administration on endogenous glucose production and lipolysis.
Temperature-dependent Pharmacokinetics and Pharmacodynamics of Vecuronium
Authors: Caldwell James E. , Heier Tom , Wright Peter M. C. , Lin Sean , McCarthy Gerald , Szenohradszky Janos , Sharma Manohar L. , Hing Jeremy P. , Schroeder Marc , Sessler Daniel I.
Published: November 2003

Background

The authors evaluated the influence of temperature on the pharmacokinetics and pharmacodynamics of vecuronium because mild core hypothermia doubles its duration of action.

Methods

Anesthesia was induced with alfentanil and propofol and maintained with nitrous oxide and isoflurane in 12 healthy volunteers. Train-of-four stimuli were applied to the ulnar nerve, and the mechanical response of the adductor pollicis was measured. Volunteers were actively cooled or warmed until their distal esophageal temperatures were in one of four ranges: < 35.0 degrees C, 35.0-35.9 degrees C, 36.0-36.9 degrees C, and > or = 37.0 degrees C. With temperature stabilized, vecuronium was infused at 5 microg x kg(-1) x min(-1) until the first response of each train-of-four had decreased by 70%. Arterial blood (for vecuronium analysis) was sampled at intervals until the first response recovered to at least 90% of its prevecuronium level. Vecuronium, 20 microg x kg(-1) x min(-1), was then infused for 10 min, and arterial blood was sampled at intervals for up to 7 h. Population-based nonlinear mixed-effects modeling was used to examine the effect of physical characteristics and core temperature on vecuronium pharmacokinetics and pharmacodynamics.

Results

Decreasing core temperature over 38.0-34.0 degrees C decreases the plasma clearance of vecuronium (11.3% per degrees C), decreases the rate constant for drug equilibration between plasma and effect site (0.023 min(-1) per degrees C), and increases the slope of the concentration-response relationship (0.43 per degrees C).

Conclusions

Our results show that reduced clearance and rate of effect site equilibration explain the increased duration of action of vecuronium with reducing core temperature. Tissue sensitivity to vecuronium is not influenced by core temperature.
Patient-controlled Interscalene Analgesia with Ropivacaine 0.2%Versus Patient-controlled Intravenous Analgesia after Major Shoulder Surgery
Authors: Borgeat Alain , Perschak Henry , Bird Patricia , Hodler Juerg , Gerber Christian
Published: November 2003

Background

The authors compared the effects of patient-controlled interscalene analgesia (PCIA) with ropivacaine 0.2% and patient-controlled intravenous analgesia (PCIVA) with opioids on hemidiaphragmatic excursion and respiratory function after major shoulder surgery.

Methods

Thirty-five patients scheduled for elective major shoulder surgery were prospectively randomized to receive either PCIA or PCIVA. All patients received an interscalene block before surgery. In the PCIA group, a catheter was introduced between the anterior and middle scalene muscles. Six hours after the initial block, patients received for 48 h either a continuous infusion of 0.2% ropivacaine through the interscalene catheter at a rate of 5 ml/h plus a bolus dose of 3 or 4 ml with a lockout time of 20 min (PCIA group) or a continuous intravenous infusion of nicomorphine at a rate or 0.5 mg/h plus a bolus dose of 2 or 3 mg with a lockout time of 20 min (PCIVA group). Hemidiaphragmatic excursion and respiratory function were assessed with the patient in a 45 degrees semirecumbent position the day before the operation and 20 min (in the operating room), 24 h, and 48 h after the initial block by means of ultrasonography and spirometry, respectively. Pain relief was regularly assessed, side effects were noted, and patient satisfaction was rated 6 h after the end of the study.

Results

Hemidiaphragmatic excursion was similar in the two groups 20 min after interscalene block. Hemidiaphragmatic excursion was increased in the PCIA group on the nonoperated side 24 and 48 h after the interscalene block (P < 0.05). Pulmonary function was similar in the two groups at each time. Pain was better controlled in the PCIA group at 12 and 24 h (P < 0.05). The incidence of nausea and vomiting were 5.5% versus 60% for the PCIA and PCIVA groups, respectively (P < 0.05). Patient satisfaction was greater in the PCIA group (P < 0.05).

Conclusions

The use of PCIA or PCIVA techniques to provide analgesia after major shoulder surgery is associated with similar effects on respiratory function. In the PCIA group, hemidiaphragmatic excursion showed a significantly greater amplitude 24 and 48 h after the initial block on the nonoperated side. The PCIA technique provided better pain control, a lower incidence of side effects, and a higher degree of patient satisfaction.
Effects of Intravenous Anesthetics on Ca2+ Sensitivity in Canine Tracheal Smooth Muscle
Authors: Hanazaki Motohiko , Jones Keith A. , Warner David O.
Published: November 2003

Background

Halothane and other volatile anesthetics relax airway smooth muscle in part by decreasing the amount of force produced for a particular intracellular calcium concentration (the Ca2+ sensitivity) during muscarinic receptor stimulation. In this study, ketamine, propofol, and midazolam were evaluated to determine whether the inhibitory effect of volatile anesthetics on this signal transduction pathway is a general property of other types of anesthetic drugs.

Methods

A beta-escin permeabilized canine tracheal smooth muscle preparation was used. Ketamine, propofol, and midazolam, in concentrations producing near-maximal relaxation in intact airway smooth muscle (200 microM, 270 microM, and 100 microM, respectively), were applied to permeabilized muscles stimulated with calcium in either the absence or the presence of muscarinic receptor stimulation provided by acetylcholine. The effect of halothane also was evaluated.

Results

Confirming previous studies, halothane (0.75 mM) decreased calcium sensitivity during muscarinic receptor stimulation. None of the intravenous anesthetics studied affected Ca2+ sensitivity, either in the absence or the presence of muscarinic receptor stimulation.

Conclusions

Intravenous anesthetics in high concentrations directly relax canine tracheal smooth muscle without affecting Ca2+ sensitivity. The inhibition of agonist-induced increases in Ca2+ sensitivity of canine tracheal smooth is not a common property of anesthetics, but is unique to volatile agents.
Preemptive Intravenous Morphine-6-glucuronide Is Ineffective for Postoperative Pain Relief
Authors: Motamed Cyrus , Mazoit Xavier , Ghanouchi Khaldoun , Guirimand Frédéric , Abhay Kou , Lieutaud Thomas , Bensaid Saïd , Fernandez Christine , Duvaldestin Philippe
Published: November 2003

Background

Morphine-6-glucuronide (M-6-G), a major metabolite of morphine, is reported to be more potent than morphine when administered intrathecally; however, its efficiency remains under debate when administered intravenously. This study was designed to assess the analgesic efficiency of intravenous M-6-G for the treatment of acute postoperative pain.

Methods

After informed consent was obtained, 37 adults (American Society of Anesthesiologists physical status I-II) who were scheduled for elective open knee surgery were enrolled in the study. General anesthesia was induced with thiopental, alfentanil, and vecuronium and was maintained with a mixture of nitrous oxide/isoflurane and bolus doses of alfentanil. At skin closure, patients were randomized into three groups: (1) morphine group (n = 13), which received morphine 0.15 mg/kg; (2) M-6-G group (n = 12), which received M-6-G 0.1 mg/kg; and (3) placebo group (n = 12), which received saline. At the time of extubation, plasma concentration of morphine and M-6-G was measured. Postoperative analgesic efficiency was assessed by the cumulative dose of morphine delivered by patient-controlled analgesia. Opioid-related side effects were also evaluated.

Results

No difference was noted in patient characteristics and opioid-related side effects. Morphine requirements (mean +/- SD) during the first 24 h in the M-6-G group (41+/-9 mg) and the placebo group (49+/-8 mg) were significantly greater (P<0.05) compared with the morphine group (29+/-8 mg).

Conclusion

A single intravenous bolus dose of M-6-G was found to be ineffective in the treatment of acute postoperative pain. This might be related to the low permeability of the blood-brain barrier for M-6-G.
Low-dose Clonidine and Neostigmine Prolong the Duration of Intrathecal Bupivacaine–Fentanyl for Labor Analgesia
Authors: Owen Medge D. , Özsaraç Özer , Şahin Şükran , Uçkunkaya Nesimi , Kaplan Nuray , Maǧunaci Ihsan
Published: November 2003

Background

Intrathecal (IT) opioid and local anesthetic combinations are popular for labor analgesia because of rapid, effective pain relief, but the duration of analgesia is limited. This study was undertaken to determine whether the addition of clonidine and neostigmine to IT bupivacaine-fentanyl would increase the duration of analgesia without increasing side effects for patients in labor.

Methods

Forty-five healthy parturients in active labor were randomized to receive a 2-ml IT dose of one of the following dextrose-containing solutions using the combined spinal-epidural technique: (1) bupivacaine 2.5 mg and fentanyl 25 microg (BF); (2) BF plus clonidine 30 microg (BFC); or (3) BFC plus neostigmine 10 microg (BFCN). Pain, sensory levels, motor block, side effects, maternal vital signs, and fetal heart rate were systematically assessed.

Results

Patients administered BFCN had significantly longer analgesia (165+/-32 min) than those who received BF (90+/-21 min; P<0.001) or BFC (123+/-21 min; P<0.001). Pain scores, block characteristics, maternal vital signs, Apgar scores, maternal satisfaction, and side effects were similar among groups except for nausea, which was significantly greater in the BFCN group (P<0.05 as compared with BFC).

Conclusions

The addition of clonidine and neostigmine significantly increased the duration of analgesia from IT bupivacaine-fentanyl during labor, but neostigmine caused more nausea. Although serious side effects were not observed in this study, safety must be further addressed before the routine use of multiple IT drugs is advocated.
Bedside Assessment of Cerebral Blood Flow by Double-indicator Dilution Technique
Authors: Wietasch Götz J. K. , Mielck Frank , Scholz Martin , von Spiegel Tilman , Stephan Heidrun , Hoeft Andreas
Published: November 2003

Background

Currently, quantitative measurement of global cerebral blood flow (CBF) at bedside is not widely performed. The aim of the present study was to evaluate a newly developed method for bedside measurement of CBF based on thermodilution in a clinical setting.

Methods

The investigation was performed in 14 anesthetized patients before coronary bypass surgery. CBF was altered by hypocapnia, normocapnia, and hypercapnia. CBF was measured simultaneously by the Kety-Schmidt inert-gas technique with argon and a newly developed transcerebral double-indicator dilution technique (TCID). For TCID, bolus injections of ice-cold indocyanine green were performed via a central venous line, and the resulting thermo-dye dilution curves were recorded simultaneously in the aorta and the jugular bulb using combined fiberoptic thermistor catheters. CBF was calculated from the mean transit times of the indicators through the brain.

Results

Both methods of measurement of CBF indicate a decrease during hypocapnia and an increase during hypercapnia, whereas cerebral metabolic rate remained unchanged. Bias between CBF(TCID) and CBFargon was -7.1+/-2.2 (SEM) ml x min(-1) x 100 g(-1); precision (+/- 2 x SD of differences) between methods was 26.6 ml x min(-1) x 100 g(-1).

Conclusions

In the clinical setting, TCID was feasible and less time-consuming than alternative methods. The authors conclude that TCID is an alternative method to measure global CBF at bedside and offers a new opportunity to monitor cerebral perfusion of patients.
Walking with Labor Epidural Analgesia
Authors: Cohen Sheila E. , Yeh Julie Y. , Riley Edward T. , Vogel Tracey M.
Published: November 2003

Background

Regional analgesia techniques for labor that permit ambulation are popular among parturients. This study evaluated the influence of bupivacaine bolus concentration and a 3-ml 1.5% lidocaine-epinephrine test dose, on analgesic effectiveness and the ability to walk after block placement.

Methods

Using a randomized double-blind study design, epidural analgesia was initiated in 60 parturients undergoing labor as follows: Group TD/B.0625 received a 3-ml lidocaine-epinephrine test dose + 12 ml bupivacaine, 0.0625%; group TD/B.125 received a 3-ml test dose + 12 ml bupivacaine, 0.125%; group B.0625 received 15 ml bupivacaine, 0.0625% (no test dose); and group B.125 received 15 ml bupivacaine, 0.125% (no test dose). Initial boluses in all groups contained 10 microg sufentanil. Bupivacaine, 0.0625%, with 0.33 microg/ml sufentanil was infused throughout labor at 13.5-15 ml/h. Analgesia balance, proprioception, motor block, and patient ability to stand and walk were evaluated at various intervals.

Results

A bolus of 0.125% bupivacaine containing sufentanil, without a previous test dose, proved to be optimal with respect to analgesia and early ambulation. When a test dose was given before bupivacaine, 0.125%, fewer women walked within 1 h of block placement. Bupivacaine, 0.0625%, with sufentanil, with or without a test dose, provided inadequate analgesia, necessitating additional bupivacaine, which impaired the ability to walk. A high percentage of women in all groups (73-93%) walked at some stage during labor.

Conclusions

Omitting a lidocaine-epinephrine test dose and using 0.125% bupivacaine for the initial bolus should permit ambulation in the early postblock period for most parturients who elect this option.