bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the Costs and Recovery Profiles of Three Anesthetic Techniques for Ambulatory Anorectal Surgery
Authors: Li Shitong , Coloma Margarita , White Paul F. , Watcha Mehernoor F. , Chiu Jen Wun , Li Hong , Huber Philip J. 
Published: November 2003

Background
Given the current practice environment, it is important to determine the anesthetic technique with the highest patient acceptance and lowest associated costs. The authors compared three commonly used anesthetic techniques for anorectal procedures in the ambulatory setting.

Methods
Ninety-three consenting adult outpatients undergoing anorectal surgery were randomly assigned to one of three anesthetic treatment groups: group 1 received local infiltration with a 30-ml mixture containing 15 ml lidocaine, 2%, and 15 ml bupivacaine, 0.5%, with epinephrine (1:200,000) in combination with intravenous sedation using a propofol infusion, 25-100 microg. kg-1. min-1; group 2 received a spinal subarachnoid block with a combination of 30 mg lidocaine and 20 microg fentanyl with midazolam, 1-2-mg intravenous bolus doses; and group 3 received general anesthesia with 2.5 mg/kg propofol administered intravenously and 0.5-2% sevoflurane in combination with 65% nitrous oxide. In groups 2 and 3, the surgeon also administered 10 ml of the previously described local anesthetic mixture at the surgical site before the skin incision.

Results
The mean costs were significantly decreased in group 1 ($69 +/- 20 compared with $104 +/- 18 and $145 +/- 25 in groups 2 and 3, respectively) because both intraoperative and recovery costs were lowest (P < 0.05). Although the surgical time did not differ among the three groups, the anesthesia time and times to oral intake and home-readiness were significantly shorter in group 1 (vs. groups 2 and 3). There was no significant difference among the three groups with respect to the postoperative side effects or unanticipated hospitalizations. However, the need for pain medication was less in groups 1 and 2 (19% and 19% vs. 45% for group 3; P < 0.05). Patients in group 1 had no complaints of nausea (vs. 3% and 26% in groups 2 and 3, respectively). More patients in group 1 (68%) were highly satisfied with the care they received than in groups 2 (58%) and 3 (39%).

Conclusions
The use of local anesthesia with sedation is the most cost-effective technique for anorectal surgery in the ambulatory setting.
Effect of Patient-triggered Ventilation on Respiratory Workload in Infants after Cardiac Surgery
Authors: Takeuchi Muneyuki , Imanaka Hideaki , Miyano Hiroshi , Kumon Keiji , Nishimura Masaji 
Published: November 2003

Background
Patient-triggered ventilation (PTV) is commonly used in adults to avoid dyssynchrony between patient and ventilator. However, few investigations have examined the effects of PTV in infants. Our objective was to determine if pressure-control PTV reduces infants' respiratory workloads in proportion to the level of pressure control. We also explored which level of pressure control provided respiratory workloads similar to those after the extubation of the trachea.

Methods
When seven post-cardiac surgery infants, aged 1 to 11 months, were to be weaned with the pressure-control PTV, we randomly applied five levels of pressure control: 0, 4, 8, 12, and 16 cm H2O. All patients were ventilated with assist-control mode, triggering sensitivity of 1 l/min, and positive end-expiratory pressure of 3 cm H2O. After establishing steady state conditions at each level of pressure control, arterial blood gases were analyzed and esophageal pressure (Pes), airway pressure, and airflow were measured. Inspiratory work of breathing (WOB) was calculated using a Campbell diagram. A modified pressure-time product (PTPmod) and the negative deflection of Pes were calculated from the Pes tracing below the baseline. The measurement was repeated after extubation.

Results
Pressure-control PTV supported every spontaneous breath. By decreasing the level of pressure control, respiratory rate increased, tidal volume decreased, and as a result, minute ventilation and arterial carbon dioxide partial pressure were maintained stable. The WOB, PTPmod, and negative deflection of Pes increased as pressure control level was decreased. The WOB and PTPmod at 4 cm H2O pressure control and 0 cm H2O pressure control and after extubation were significantly greater than those at the pressure control of 16, 12, and 8 cm H2O (P < 0.05). The WOB and PTPmod were almost equivalent after extubation and at 4 cm H2O pressure control.

Conclusions
Work of breathing and PTPmod were changed according to the pressure control level in post-cardiac surgery infants. PTV may be feasible in infants as well as in adults.
Sex Differences in Morphine Analgesia
Authors: Sarton Elise , Olofsen Erik , Romberg Raymonda , den Hartigh Jan , Kest Benjamin , Nieuwenhuijs Diederik , Burm Anton , Teppema Luc , Dahan Albert 
Published: November 2003

Background
Animal and human studies indicate the existence of important sex-related differences in opioid-mediated behavior. In this study the authors examined the influence of morphine on experimentally induced pain in healthy male and female volunteers.

Methods
Young healthy men and women (10 of each sex) received intravenous morphine (bolus 0.1-mg/kg dose followed by an infusion of 0.030 mg. kg-1. h-1 for 1 h). Pain threshold and pain tolerance in response to a gradual increase in transcutaneous electrical stimulation, as well as plasma concentrations of morphine and its major metabolites (morphine-6-glucuronide and morphine-3-glucuronide) were determined at regular intervals up to 7 h after the start of morphine infusion. A population pharmacodynamic model was used to analyze the morphine-induced changes in stimulus intensity. The improvement of the model fits by inclusion of covariates (sex, age, weight, lean body mass) was tested for significance. The model is characterized by baseline current, a rate constant for equilibrium between plasma and effect-site morphine concentrations (ke0), and analgesic potency (AC50, or the morphine concentration causing a 100% increase in stimulus intensity for response).

Results
The inclusion of the covariates age, weight, and lean body mass did not improve the model fits for any of the model parameters. For both pain threshold and tolerance, a significant dependency on sex was observed for the parameters ke0 (pain threshold: 0.0070 +/- 0.0013 (+/- SE) min-1 in men vs. 0.0030 +/- 0. 0005 min-1 in women; pain tolerance: 0.0073 +/- 0.0012 min-1 in men vs. 0.0024 +/- 0.0005 min-1 in women) and AC50 (pain threshold: 71.2 +/- 10.5 nm in men vs. 41.7 +/- 8.4 nm in women; pain tolerance: 76. 5 +/- 7.4 nm in men vs. 32.9 +/- 7.9 nm in women). Baseline currents were similar for both sexes: 21.4 +/- 1.6 mA for pain threshold and 39.1 +/- 2.3 mA for pain tolerance. Concentrations of morphine, morphine-3-glucuronide, and morphine-6-glucuronide did not differ between men and women.

Conclusions
These data show sex differences in morphine analgesia, with greater morphine potency but slower speed of onset and offset in women. The data are in agreement with observations of sex differences in morphine-induced respiratory depression and may explain higher postoperative opioid consumption in men relative to women.
Neuroprotective Effects of Riluzole and Ketamine during Transient Spinal Cord Ischemia in the Rabbit
Authors: Lips Jeroen , de Haan Peter , Bodewits Pieter , Vanicky Ivo , Dzoljic Misa , Jacobs Michael J. , Kalkman Cor J. 
Published: November 2003

Background
Massive release of central excitatory neurotransmitters is an important initial step in ischemic neuronal injury, and modification of this process may provide neuroprotection. We studied the protective effects of the voltage-dependent sodium channel antagonist riluzole and the N-methyl-d-aspartate receptor antagonist ketamine on hind limb motor function and histopathologic outcome in an experimental model of spinal cord ischemia.

Methods
Temporary spinal cord ischemia was induced by 29 min of infrarenal balloon occlusion of the aorta in 60 anesthetized New Zealand white rabbits. Animals were randomly assigned to one of four treatment groups (n = 15 each): group C, saline (control); group R, riluzole, 8 mg/kg intravenously; group K, ketamine, 55 mg/kg intravenously; group RK, riluzole and ketamine. After reperfusion, riluzole treatment was continued with intraperitoneal infusions. Normothermia (38 degrees C) was maintained during ischemia, and rectal temperature was assessed before and after intraperitoneal infusions. Neurologic function, according to Tarlov's criteria, was evaluated every 24 h, and infarction volume and the number of eosinophilic neurons and viable motoneurons in the lumbosacral spinal cord was evaluated after 72 h.

Results
Neurologic outcome was better in groups R and RK than in groups C and K. All animals in group C (100%) and all animals but one in group K (93%) were paraplegic 72 h after the ischemic insult versus 53% in group R and 67% in group RK (P < 0.01 each). More viable motoneurons were present in groups R and RK than in controls (P < 0.05).

Conclusions
The data indicate that treatment with riluzole can increase the tolerance of spinal cord motoneurons to a period of normothermic ischemia. Intraischemic ketamine did not provide neuroprotection in this model.
Altered Expression of Cardiac Myosin Isozymes Associated with the Malignant Hyperthermia Genotype in Swine
Authors: Liou Ying-Ming , Jiang Meei Jyh , Wu Ming-Che 
Published: November 2003

Background
Anesthetic-induced malignant hyperthermia (MH) in humans and pigs is associated with dramatic alterations in cardiac function. However, it remains controversial as to whether MH-associated cardiac symptoms represent a primary difference of myocardium or a secondary alteration consequent to increases in the hyperthermic stress. Here the authors describe changes in myosin isoform expression in the hearts of MH-susceptible pigs with and without prior exposure to halothane.

Methods
One group of pigs was diagnosed as MH susceptible by halothane challenge and Hal-1843 nucleotide examination. To determine if there is an effect of halothane exposure, another group of pigs was diagnosed by simple MH genotyping without exposure to halothane. After diagnosis and genotyping, animals with and without exposure to halothane were killed to study cardiac myosin isozyme distributions, cardiac myofibrillar adenosine triphosphatase (ATPase) activity, and the steepness of the Ca2+-ATPase activity relation in the hearts of normal and susceptible pigs. The altered myosin isozyme expression was analyzed by pyrophosphate gel electrophoresis.

Results
Malignant hyperthermia-susceptible animals with the prior halothane challenge showed an increased V1 myosin (-44%) expression, increased myofibrillar ATPase activity (-25%) and increased steepness of the Ca2+-ATPase activity relation. Without exposure to halothane, no change of myofibrillar ATPase activity was found in the hearts of different genotyped pigs, but there was a small increase in expression of V1 myosin (-5%) in the mutant (TT).

Conclusions
The potential modulation of V1 myosin expression occurs in the hearts of MH-susceptible pigs. The added stress by halothane challenge would further cause a V3 --> V1 shift, which may be attributed to the long-term effects of hyperthermic stress.
Accuracy and Reliability of the Self-inflating Bulb to Verify Tracheal Intubation in Out-of-hospital Cardiac Arrest Patients
Authors: Tanigawa Koichi , Takeda Taku , Goto Eiichi , Tanaka Keiichi 
Published: November 2003

Background
To determine the sensitivity and specificity of the self-inflating bulb (SIB) to verify tracheal intubation in out-of-hospital cardiac arrest patients.

Methods
Sixty-five consecutive adult patients with out-of-hospital cardiac arrest were enrolled. Patients were provided chest compression and ventilation by either ba-valve-mask or the esophageal tracheal double-lumen airway by ambulance crews when they arrived at the authors' department. Immediately after intubation in the emergency department, the endotracheal tube position was tested by the SIB and end-tidal carbon dioxide (ETCO2) monitor using an infrared carbon dioxide analyzer. We observed the SIB reinflating for 10 s, and full reinflation within 4 s was defined as a positive result (tracheal intubation).

Results
Five esophageal intubations occurred, and the SIB correctly identified all esophageal intubations. Of the 65 tracheal intubations, the SIB correctly identified 47 tubes placed in the trachea (72.3%). Delayed but full reinflation occurred in one tracheal intubation during the 10-s observation period. Fifteen tracheal intubations had incomplete reinflation during the observation period, and two tracheal intubations did not achieve any reinflation. Thirty-nine tracheal intubations were identified by ETCO2 (60%). When the SIB test is combined with the ETCO2 detection, 59 tracheal intubations were identified with a 90.8% sensitivity.

Conclusions
The authors found a high incidence of false-negative results of the SIB in out-of-hospital cardiac arrest patients. Because no single test for verifying endotracheal tube position is reliable, all available modalities should be tested and used in conjunction with proper clinical judgment to verify tracheal intubation in cases of out-of-hospital cardiac arrest.
Influence of Hypovolemia on the Pharmacokinetics and the Electroencephalographic Effect of Propofol in the Rat
Authors: De Paepe Peter , Belpaire Frans M. , Rosseel Marie T. , Van Hoey Gert , Boon Paul A. , Buylaert Walter A. 
Published: November 2003

Background
Hypovolemia decreases the dose requirement for anesthetics, but no data are available for propofol. As it is impossible to study this in patients, a rat model was used in which the influence of hypovolemia on the pharmacokinetics and pharmacodynamics of propofol was investigated.

Methods
Animals were randomly allocated to either a control (n = 9) or a hypovolemia (n = 9) group, and propofol was infused (150 mg x kg(-1) x h(-1)) until isoelectric periods of 5 s or longer were observed in the electroencephalogram. The changes observed in the electroencephalogram were quantified using aperiodic analysis and used as a surrogate measure of hypnosis. The righting reflex served as a clinical measure of hypnosis.

Results
The propofol dose needed to reach the electroencephalographic end point in the hypovolemic rats was reduced by 60% (P < 0.01). This could be attributed to a decrease in propofol clearance and in distribution volume. Protein binding was similar in both groups. To investigate changes in end organ sensitivity during hypovolemia, the electroencephalographic effect versus effect-site concentration relation was studied. The effect-blood concentration relation was biphasic, exhibiting profound hysteresis in both hypovolemic and control animals. Semiparametric minimization of this hysteresis revealed similar equilibration half-lives in both groups. The biphasic effect-concentration relation was characterized by descriptors showing an increased potency of propofol during hemorrhage. The effect-site concentration at the return of righting reflex was 23% (P < 0.01) lower in the hypovolemic animals, also suggesting an increased end organ sensitivity.

Conclusions
An increased hypnotic effect of propofol occurs during hypovolemia in the rat and can be attributed to changes in both pharmacokinetics and end organ sensitivity.
Measurement of Individual Clinical Productivity in an Academic Anesthesiology Department
Authors: Abouleish Amr E. , Zornow Mark H. , Levy Ronald S. , Abate James , Prough Donald S. 
Published: November 2003

Background
The ability to measure productivity, work performed, or contributions toward the clinical mission has become an important issue facing anesthesiology departments in private practice and academic settings. Unfortunately, the practice and billing of anesthesia services makes it difficult to quantify individual productivity. This study examines the following methods of measuring individual productivity: normalized clinical days per year (nCD/yr); time units per operating-room day worked (TU/OR day); normalized time units per year (nTU/yr); total American Society of Anesthesiologists (ASA) units per OR day (tASA/OR day); and normalized total ASA units per year (ntASA/yr).

Methods
Billing and scheduling data for clinical activities of faculty members of an anesthesiology department at a university medical center were collected and analyzed for the 1998 fiscal year. All clinical sites and all clinical faculty anesthesiologists were included unless they spent less than 20% of their time during the fiscal year providing clinical care, i.e., less than 0.2 clinical full-time equivalent. Outliers, defined as faculty who had productivity greater or less than 1 SD from the mean, were examined in detail.

Results
Mean and median values were reported for each measurement, and different groups of outliers were identified. nCD/yr identified faculty who worked more than their clinical full-time equivalent would have predicted. TU/OR day and tASA/OR day identified apparently low-productivity faculty as those who worked a large portion of their time in obstetric anesthesia or an ambulatory surgicenter. tASA/OR day identified specialty anesthesiologists as apparently high-productivity faculty. nTU/yr and ntASA/yr were products of the per-OR day measurement and nCD/yr.

Conclusion
Each of the measurements studied values certain types of productivity more than others. By defining what type of service is most important to reward, the most appropriate measure or combination of measures of productivity can be chosen. In the authors' department, nCD/yr is the most useful measure of individual productivity because it measures an individual anesthesiologist's contribution to daily staffing, includes all clinical sites, is independent of nonanesthesia factors, and is easy to collect and determine.
Peribulbar versus Retrobulbar Anesthesia for Ophthalmic Surgery
Authors: Ripart Jacques , Lefrant Jean-Yves , de La Coussaye Jean-Emmanuel , Prat-Pradal Dominique , Vivien Bruno , Eledjam Jean-Jacques 
Published: November 2003

Background
Peribulbar and retrobulbar anesthesia have long been opposed on the basis of the existence of an intermuscular membrane, which is supposed to separate the intraconal from the extraconal spaces in a water-tight fashion. A local anesthetic injected outside the cone should spread through this septum to reach the nerves to be blocked. The existence of this septum is questioned. The aim of this study was to compare the spread of a colored latex dye injected intraconally or extraconally to simulate both retrobulbar and peribulbar anesthesia.

Methods
The authors used 10 heads from human cadavers. For each head, one eye was injected intraconally, and the other eye was injected extraconally. The heads were then frozen and sectioned into thin slices following various planes. They were then photographed and observed.

Results
There was no evidence of the existence of an intermuscular septum separating the intraconal and extraconal spaces. Those two spaces appeared to be part of a common spreading space, the corpus adiposum of the orbit.

Conclusions
These results are in accord with the fact that clinical studies were not able to clearly demonstrate that retrobulbar anesthesia is more efficient than peribulbar anesthesia. On the basis of a similar clinical efficacy of the two techniques as a result of similar spreading of the local anesthetic injected, and a potentially higher risk of introducing the needle into the muscular cone, the authors recommend replacing retrobulbar anesthesia with peribulbar anesthesia.
Cytochrome P-450 2B6 Is Responsible for Interindividual Variability of Propofol Hydroxylation by Human Liver Microsomes
Authors: Court Michael H. , Duan Su X. , Hesse Leah M. , Venkatakrishnan Karthik , Greenblatt David J. 
Published: November 2003

Background
Oxidation of propofol to 4-hydroxypropofol represents a significant pathway in the metabolism of this anesthetic agent in humans. The aim of this study was to identify the principal cytochrome P-450 (CYP) isoforms mediating this biotransformation.

Methods
Propofol hydroxylation activities and enzyme kinetics were determined using human liver microsomes and cDNA-expressed CYPs. CYP-specific marker activities and CYP2B6 protein content were also quantified in hepatic microsomes for correlational analyses. Finally, inhibitory antibodies were used to ascertain the relative contribution of CYPs to propofol hydroxylation by hepatic microsomes.

Results
Propofol hydroxylation by hepatic microsomes showed more than 19-fold variability and was most closely correlated to CYP2B6 protein content (r = 0.904), and the CYP2B6 marker activities, S-mephenytoin N-demethylation (r = 0.919) and bupropion hydroxylation (r = 0.854). High- and intermediate-activity livers demonstrated high-affinity enzyme kinetics (K(m) < 8 microm), whereas low-activity livers displayed low-affinity kinetics (K(m) > 80 microm). All of the CYPs evaluated were capable of hydroxylating propofol; however, CYP2B6 and CYP2C9 were most active. Kinetic analysis indicated that CYP2B6 is a high-affinity (K(m) = 10 +/- 2 microm; mean +/- SE of the estimate), high-capacity enzyme, whereas CYP2C9 is a low-affinity (K(m) = 41 +/- 8 microm), high-capacity enzyme. Furthermore, immunoinhibition showed a greater contribution of CYP2B6 (56 +/- 22% inhibition; mean +/- SD) compared with CYP2C isoforms (16 +/- 7% inhibition) to hepatic microsomal activity.

Conclusions
Cytochrome P-450 2B6, and to a lesser extent CYP2C9, contribute to the oxidative metabolism of propofol. However, CYP2B6 is the principal determinant of interindividual variability in the hydroxylation of this drug by human liver microsomes.
Leukocytes Can Enhance Platelet-mediated Aggregation and Thromboxane Release via Interaction of P-selectin Glycoprotein Ligand 1 with P-selectin
Authors: Faraday Nauder , Scharpf Robert B. , Dodd-o Jeffrey M. , Martinez Elizabeth A. , Rosenfeld Brian A. , Dorman Todd 
Published: November 2003

Background
Platelet--leukocyte conjugates have been observed in patients with unstable coronary syndromes and after cardiopulmonary bypass. In vitro, the binding of platelet P-selectin to leukocyte P-selectin glycoprotein ligand-1 (PSGL1) mediates conjugate formation; however, the hemostatic implications of these cell--cell interactions are unknown. The aims of this study were to determine the ability of leukocytes to modulate platelet agonist--induced aggregation and secretion in the blood milieu, and to investigate the role of P-selectin and PSGL-1 in mediating these responses.

Methods
Blood was drawn from healthy volunteers for in vitro analysis of platelet agonist--induced aggregation, secretion (adenosine triphosphate, beta-thromboglobulin, and thromboxane), and platelet-leukocyte conjugate formation. Experiments were performed on live cells in whole blood or plasma to simulate physiologic conditions. Whole-blood impedance and optical aggregometry, flow cytometry, and enzyme-linked immunosorbent assays were performed in the presence and absence of blocking antibodies to P-selectin and PSGL1. The platelet-specific agonists, thrombin receptor activating peptide and adenosine diphosphate, were used to elicit platelet activation responses.

Results
Inhibition of platelet--leukocyte adherence by P- selectin and PSGL1 antibodies decreased agonist--induced aggregation in whole blood. The presence of leukocytes in platelet-rich plasma increased aggregation, and this increase was attenuated by P-selectin blocking antibodies. Data from flow cytometry confirmed that platelet-leukocyte conjugate formation contributed to aggregation responses. Blocking antibodies reduced platelet agonist--induced thromboxane release but had no impact on adenosine triphosphate and beta-thomboglobulin secretion.

Conclusions
Leukocytes can enhance platelet agonist--induced aggregation and thromboxane release in whole blood and platelet-rich plasma under shear conditions in vitro. Interaction of platelet P-selectin with leukocyte PSGL1 contributes substantially to these effects.