bluuebunny/crossref_metadata_2025 huggingface dataset:
Narcotrend Monitoring Allows Faster Emergence and a Reduction of Drug Consumption in Propofol–Remifentanil Anesthesia
Authors: Kreuer Sascha , Biedler Andreas , Larsen Reinhard , Altmann Simone , Wilhelm Wolfram
Published: November 2003

Background

The Narcotrend is a new electroencephalographic monitor designed to measure depth of anesthesia, based on a six-letter classification from A (awake) to F (increasing burst suppression) including 14 substages. This study was designed to investigate the impact of Narcotrend monitoring on recovery times and propofol consumption in comparison to Bispectral Index (BIS) monitoring or standard anesthetic practice.

Methods

With institutional review board approval and written informed consent, 120 adult patients scheduled to undergo minor orthopedic surgery were randomized to receive a propofol-remifentanil anesthetic controlled by Narcotrend, by BIS(R), or solely by clinical parameters. Anesthesia was induced with 0.4 micro x kg-1 x min-1 remifentanil and a propofol target-controlled infusion at 3.5 microg/ml. After intubation, remifentanil was reduced to 0.2 micro x kg-1 x min-1, whereas the propofol infusion was adjusted according to clinical parameters or to the following target values: during maintenance to D(0) (Narcotrend) or 50 (BIS); 15 min before the end of surgery to C(1) (Narcotrend) or 60 (BIS). Recovery times were recorded by a blinded investigator, and average normalized propofol consumption was calculated from induction and maintenance doses.

Results

The groups were comparable for demographic data, duration of anesthesia, and mean remifentanil dosages. Compared with standard practice, patients with Narcotrend or BIS monitoring needed significantly less propofol (standard practice, 6.8 +/- 1.2 mg x kg-1 x h-1 vs. Narcotrend, 4.5 +/- 1.1 mg x kg-1 x h-1 or BIS(R), 4.8 +/- 1.0 mg x kg-1 x h-1; P < 0.001), opened their eyes earlier (9.3 +/- 5.2 vs. 3.4 +/- 2.2 or 3.5 +/- 2.9 min), and were extubated sooner (9.7 +/- 5.3 vs. 3.7 +/- 2.2 or 4.1 +/- 2.9 min).

Conclusions

The results indicate that Narcotrend and BIS monitoring are equally effective to facilitate a significant reduction of recovery times and propofol consumption when used for guidance of propofol titration during a propofol-remifentanil anesthetic.
Evaluation of a New Point-of-care Celite-activated Clotting Time Analyzer in Different Clinical Settings
Authors: Paniccia Rita , Fedi Sandra , Carbonetto Fiorella , Noferi Daniela , Conti Paolo , Bandinelli Brunella , Giusti Betti , Evangelisti Lucia , Pretelli Paola , Palmarini Mara F.G. , Abbate Rosanna , Prisco Domenico
Published: November 2003

Background

Activated clotting time (ACT) is used to monitor heparin therapy during cardiopulmonary bypass, interventional cardiology, and hemodialysis. Traditionally, ACT is performed by use of the Hemochron system. Recently, a new device, the i-STAT system, has been introduced to measure ACT. The aim of this study was to correlate the performances of these two systems and to compare ACT values with heparin levels.

Methods

One hundred sixty-five samples from 29 patients undergoing cardiopulmonary bypass or hemodialysis were assayed in duplicate with two Hemochron and two i-STAT devices. Heparin levels were determined by anti-factor Xa assay.

Results

The Hemochron ACT ranged from 88 to 1,028 s, and the i-STAT ACT ranged from 80 to 786 s. Heparin plasma levels ranged from 0.01 to 10.8 U/mL. Bland-Altman analysis showed a mean difference between the two methods of 24 +/- 101 s. Strong relationships between anti-factor Xa activity and Hemochron ACTs (r2 = 0.69, P < 0.001) and i-STAT ACTs (r2 = 0.79, P < 0.001) were observed. During cardiac surgery, significant correlations were found: Hemochron, r2 = 0.61, P < 0.001 and i-STAT, r2 = 0.74, P < 0.001. During hemodialysis, relationships between anti-factor Xa activity and ACTs were found: Hemochron, r2 = 0.62, P < 0.001 and i-STAT, r2 = 0.55, P < 0.001.

Conclusions

During cardiopulmonary bypass procedure and hemodialysis, i-STAT provides measurements of clotting time quite similar to Hemochron ACT, which were significantly correlated with heparin levels.
Protection with Antibody to Tumor Necrosis Factor Differs with Similarly Lethal Escherichia coli versus Staphylococcus aureus Pneumonia in Rats
Authors: Karzai Waheedullah , Cui Xizhong , Mehlhorn Bjoern , Straube Eberhard , Hartung Thomas , Gerstenberger Eric , Banks Steven M. , Natanson Charles , Reinhart Konrad , Eichacker Peter Q.
Published: November 2003

Background

Differing factors may alter the effects of antibody to tumor necrosis factor (TNF) in infection and sepsis. The authors tested whether bacteria type or treatment route alters antibody to TNF in a rat model of bacterial pneumonia.

Methods

Rats (n = 231) received similarly lethal doses of either intratracheal Escherichia coli or Staphylococcus aureus followed by treatment with either intratracheal or intraperitoneal antibody to TNF or control serum. Animals received antibiotics (cefotiam daily dose, 100 mg/kg) starting 4 h after inoculation and were studied for up to 96 h.

Results

Compared with S. aureus, E. coli increased serum TNF and interleukin-6 concentrations, lung lavage TNF concentrations, neutrophil counts, and alveolar-to-arterial oxygen gradients and decreased circulating neutrophils and lymphocytes (P > or = 0.05 for all). Compared with controls, with both bacteria, except for lung lavage TNF concentrations (which decreased with intratracheal but not with intraperitoneal antibody to TNF), treatment route did not alter the effects of antibody to TNF on any parameter (P = not significant for all). Antibody to TNF reduced mortality rates (relative risk of death +/- SEM) with both E. coli (-1.6 +/- 0.6; P = 0.006) and S. aureus (-0.5 +/- 0.04; P = 0.185), but these reductions were greater with E. coli than with S. aureus in a trend approaching statistical significance (P = 0.09). Compared with controls, similarly (P = not significant) with both bacteria, antibody to TNF decreased lung lavage and tissue bacteria concentrations (both P < 0.05) and serum TNF concentration (P < 0.09) and increased circulating neutrophils and lymphocytes (both P < or = 0.01). Compared with S. aureus, with E. coli antibody to TNF decreased alveolar-to-arterial oxygen gradients (P = 0.04) and increased serum interleukin-6 concentrations (P = 0.003).

Conclusion

Antibody to TNF improved host defense and survival rates with both lethal E. coli and S. aureus pneumonia, but protection was greater with E. coli, where TNF concentrations were higher than with S. aureus. The efficacy of antiinflammatory agents in sepsis may be altered by bacteria type.
Uterine Cervical Distension Induces cFos Expression in Deep Dorsal Horn Neurons of the Rat Spinal Cord
Authors: Tong Chuanyao , Ma Weiya , Shin Sang-Wook , James Robert L. , Eisenach James C.
Published: November 2003

Background

Uterine cervical distension underlies labor pain, yet its neurophysiology and pharmacology of inhibition remain unexplored. The authors examined uterine cervical distension-evoked cFos immunoreactivity in rat spinal cords, and the inhibitory effect of spinal cyclo-oxygenase inhibition on cFos expression.

Methods

Female rats were anesthetized with halothane, and pairs of metal rods were inserted in each cervical os through a mid-line laparotomy. A submaximal distension force (75 g) was applied for either 30 or 60 min, or, in control animals, no force was applied. Other animals received cervical lidocaine infiltration prior to uterine cervical distension. At the end of the experiments, the spinal cord at T12 to L2 levels was harvested and immunostained for cFos protein. Other animals received intrathecal ketorolac (0, 5, 25, and 50 microg; n = 5-6 for each group) prior to uterine cervical distension.

Results

Uterine cervical distension significantly increased cFos immunoreactivity in the spinal cord from T12 to L2, with most cFos expression in the deep dorsal and central canal regions. Surgical preparation alone without uterine cervical distension resulted in minimal cFos expression, primarily in the superficial dorsal horn. Uterine cervical distension-evoked cFos expression was prevented by prior infiltration of lidocaine into the cervix. Intrathecal ketorolac produced a dose-dependent inhibition of uterine cervical distension-induced cFos expression.

Conclusion

The present study demonstrates that uterine cervical distension results in a similar pattern of spinal cord neuronal activation as seen with other noxious visceral stimuli. The inhibition of cFos expression by intrathecal ketorolac suggests that spinal cyclo-oxygenase plays a role in uterine cervical distension-induced nociception.
Pharmacokinetics of Midazolam in Neonates Undergoing Extracorporeal Membrane Oxygenation
Authors: Mulla Hussain , McCormack Peter , Lawson Graham , Firmin Richard K. , Upton David Robert
Published: November 2003

Background

Although the pharmacokinetics of midazolam in critically ill children has been described, there are no such reports in extracorporeal membrane oxygenation.

Methods

The pharmacokinetics of midazolam and 1-hydroxy midazolam after continuous infusion (50-250 microg. kg(-1). h(-1)) were determined in 20 neonates undergoing extracorporeal membrane oxygenation. Patients were randomized into two groups: group 1 (n = 10) received midazolam extracorporeally (into the circuit), and group 2 received drug via central or peripheral access. Blood samples for determination of plasma concentrations were taken at baseline, 2, 4, 6, 12, 18, and 24 h, then every 12 h. Population pharmacokinetic analysis and model building was conducted using WinNonMix (Pharsight Corporation, Mountain View, CA). The 1-hydroxy midazolam/midazolam metabolic ratio was determined as a surrogate marker of cytochrome P450 3A activity.

Results

The parameter estimates (n = 19) were based on a one-compartment model with time-dependent change in volume of distribution. Volume (mean +/- standard error) expanded monoexponentially from the onset of extracorporeal membrane oxygenation to a maximum value, 0.8 l +/- 0.5 and 4.1 +/- 0.5 l/kg, respectively. Consequently, plasma half-life was substantially prolonged (median [range]) from onset to steady-state: 6.8 (2.2-39.8) and 33.3 (7.4-178) h, respectively. Total body clearance was determined as (mean +/- standard error) 1.4 +/- 0.15 ml. kg-1. min-1. The median metabolic ratio was 0.17 (0.03-0.9). No significant differences were observed between the two groups with respect to parameter estimates. Simulations of plasma concentration profiles revealed excess levels at conventional doses.

Conclusions

These results reveal significantly increased volume of distribution and plasma half-life in neonates receiving extracorporeal membrane oxygenation. Altered kinetics may reflect sequestration of midazolam by components of the extracorporeal membrane oxygenation circuit.
Performance of Noninvasive Partial CO2Rebreathing Cardiac Output and Continuous Thermodilution Cardiac Output in Patients Undergoing Aortic Reconstruction Surgery
Authors: Kotake Yoshifumi , Moriyama Kiyoshi , Innami Yasushi , Shimizu Hideyuki , Ueda Toshihiko , Morisaki Hiroshi , Takeda Junzo
Published: November 2003

Background

In the partial CO(2) rebreathing method, monitored changes in CO(2) elimination and end-tidal CO(2) in response to a brief rebreathing period are used to estimate cardiac output. However, dynamic changes in CO(2) production during ischemia and reperfusion may affect the accuracy of these estimates. This study was designed to compare measurements of cardiac output as produced by the partial CO(2) rebreathing (NICO), bolus (BCO), and continuous thermodilution (CCO) methods of monitoring cardiac output.

Methods

Cardiac output was continuously monitored using both NICO and CCO in 28 patients undergoing aortic reconstruction. BCO measurements were taken at the following intervals when hemodynamic stability was achieved: (1) after anesthetic induction; (2) during aortic cross-clamp; (3) at reperfusion of the iliac artery; and, (4) during peritoneal closure.

Results

The bias and precision (1 SD) derived from all the measurements between NICO and BCO was -0.58 +/- 0.9 l/min, whereas for CCO and BCO it was 0.38 +/- 1.17 l/min. The bias between NICO and BCO was small after anesthetic induction and during cross-clamp, but increased following reperfusion. The bias between CCO and BCO was relatively small until reperfusion but increased significantly at peritoneal closure.

Conclusions

Results indicate that in aortic reconstruction surgery the performance of NICO monitoring is comparable with that of CCO; however, the direction of bias in these continuous measurement devices is the opposite.
Using the Time of Maximum Effect Site Concentration to Combine Pharmacokinetics and Pharmacodynamics
Authors: Minto Charles F. , Schnider Thomas W. , Gregg Keith M. , Henthorn Thomas K. , Shafer Steven L.
Published: November 2003

Background

To simulate the time course of drug effect, it is sometimes necessary to combine the pharmacodynamic parameters from an integrated pharmacodynamic-pharmacodynamic study (e.g., volumes, clearances, k(e0) [the effect site equilibration rate constant], C(50) [the steady state plasma concentration associated with 50% maximum effect], and the Hill coefficient) with pharmacokinetic parameters from a different study (e.g., a study examining a different age group or sampling over longer periods of time). Pharmacokinetic-pharmacodynamic parameters form an interlocked vector that describes the relationship between input (dose) and output (effect). Unintended consequences may result if individual elements of this vector (e.g., k(e0)) are combined with pharmacokinetic parameters from a different study. The authors propose an alternative methodology to rationally combine the results of separate pharmacokinetic and pharmacodynamic studies, based on t(peak), the time of peak effect after bolus injection.

Methods

The naive approach to combining separate pharmacokinetic and pharmacodynamic studies is to simply take the k(e0) from the pharmacodynamic study and apply it naively to the pharmacokinetic study of interest. In the t(peak) approach, k(e0) is recalculated using the pharmacokinetics of interest to yield the correct time of peak effect. The authors proposed that the t(peak) method would yield better predictions of the time course of drug effect than the naive approach. They tested this hypothesis in three simulations: thiopental, remifentanil, and propofol.

Results

In each set of simulations, the t(peak) method better approximated the postulated "true" time course of drug effect than the naive method.

Conclusions

T(peak) is a useful pharmacodynamic parameter and can be used to link separate pharmacokinetic and pharmacodynamic studies. This addresses a common difficulty in clinical pharmacology simulation and control problems, where there is usually a wide choice of pharmacokinetic models but only one or two published pharmacokinetic-pharmacodynamic models. The results will be immediately applicable to target-controlled anesthetic infusion systems, where linkage of separate pharmacokinetic and pharmacodynamic parameters into a single model is inherent in several target-controlled infusion designs.
Anesthetic Preconditioning
Authors: Kevin Leo G. , Katz Peter , Camara Amadou K. S. , Novalija Enis , Riess Matthias L. , Stowe David F.
Published: November 2003

Background

Anesthetic preconditioning (APC) is protective for several aspects of cardiac function and structure, including left ventricular pressure, coronary flow, and infarction. APC may be protective, however, only if the duration of ischemia is within a certain, as yet undefined range. Brief ischemia causes minimal injury, and APC would be expected to provide little benefit. Conversely, very prolonged ischemia would ultimately cause serious injury with or without APC. Previous investigations used a constant ischemic time as the independent variable to assess ischemia-induced changes in dependent functional and structural variables. The purpose of the study was to define the critical limits of efficacy of APC by varying ischemic time.

Methods

Guinea pig hearts (Langendorff preparation; n = 96) underwent pretreatment with sevoflurane (APC) or no treatment (control), before global ischemia and 120 min reperfusion. Ischemia durations were 20, 25, 30, 35, 40, and 45 min.

Results

At 120 min reperfusion, developed (systolic-diastolic) left ventricular pressure was increased by APC compared with control for ischemia durations of 25-40 min. Infarction was decreased by APC for ischemia durations of 25-40 min, but not 20 or 45 min. APC improved coronary flow and vasodilator responses for all ischemia durations longer than 25 min, and decreased ventricular fibrillation on reperfusion for ischemia durations longer than 30 min.

Conclusions

Although APC protects against vascular dysfunction and dysrhythmias after prolonged ischemia, protection against contractile dysfunction and infarction in this model is restricted to a range of ischemia durations of 25-40 min. These results suggest that APC may be effective in a subset of patients who have cardiac ischemia of intermediate duration.
Embolism Bubble Adhesion Force in Excised Perfused Microvessels
Authors: Suzuki Akira , Eckmann David M.
Published: November 2003

Background

The mechanics of gas embolism bubble adhesion to the vessel wall is poorly understood. New strategies to treat gas embolism may result from an understanding of adhesion forces, including the molecular determinants of bubble adhesion. The authors conducted experiments to measure the adhesion force of bubbles contacting the vessel wall.

Methods

Microbubbles were injected into excised arterioles. Bubbles resided for 5, 10, 20, or 30 min with the endothelium intact or damaged and with a physiologic salt solution, physiologic salt solution with 5% bovine serum albumin, or rat serum as the perfusate. Inflow pressure was raised until the bubble dislodged. The differential pressure across the microbubble, deltaP, was recorded at the moment of bubble movement. Bubble diameter, D, and length, L, were determined by videomicroscopy. The adhesion force per unit surface area of a bubble contacting the vessel wall, K = deltaPD/4 L, was calculated for each experiment.

Results

K at 10 min contact time (physiologic salt solution, 141 +/- 29; serum, 153 +/- 57 dyne/cm2) was higher than at 5 min (physiologic salt solution, 56 +/- 22; serum, 71 +/- 29 dyne/cm2), 20 min (physiologic salt solution, 46 +/- 29) and 30 min (physiologic salt solution, 14 +/- 5) (P < 0.05). Endothelium removal reduced K at 10 min (physiologic salt solution, 68 +/- 46; serum, 60 +/- 14 dyne/cm2) (P < 0.05). K was higher with 5% bovine serum albumin present at 10 min (349 +/- 149, P < 0.05), correlating with in vivo estimates.

Conclusions

The adhesion force developed between a microbubble and the vessel wall depends on multiple factors, including bubble residence time, presence of the endothelium, and perfusion solution.
Interaction between the Spinal Melanocortin and Opioid Systems in a Rat Model of Neuropathic Pain
Authors: Vrinten Dorien H. , Gispen Willem Hendrik , Kalkman Cor J. , Adan Roger A. H.
Published: November 2003

Background

The authors recently demonstrated that administration of the melanocortin-4 receptor antagonist SHU9119 decreased neuropathic pain symptoms in rats with a sciatic chronic constriction injury. The authors hypothesised that there is a balance between tonic pronociceptive effects of the spinal melanocortin system and tonic antinociceptive effects of the spinal opioid system. Therefore, they investigated a possible interaction between these two systems and tested whether opioid effectiveness could be increased through modulation of the spinal melanocortin system activity.

Methods

In chronic constriction injury rats, melanocortin and opioid receptor ligands were administered through a lumbar spinal catheter, and their effects on mechanical allodynia were assessed by von Frey probing.

Results

Naloxone (10-100 microg) dose-dependently increased allodynia (percent of maximum possible effect of -67 +/- 9%), which is in agreement with a tonic antinociceptive effect of the opioid system. SHU9119 decreased allodynia (percent of maximum possible effect of 60 +/- 13%), and this effect could be blocked by a low dose of naloxone (0.1 microg), which by itself had no effect on withdrawal thresholds. Morphine (1-10 microg) dose-dependently decreased allodynia (percent of maximum possible effect of 73 +/- 14% with the highest dose tested). When 0.5 microg SHU9119 (percent of maximum possible effect of 47 +/- 14%) was given 15 min before morphine, there was an additive antiallodynic effect of both compounds.

Conclusions

Together, these data confirm that there is an interaction between the spinal melanocortin and opioid systems and that combined treatment with melanocortin-4 receptor antagonists and opioids might possibly contribute to the treatment of neuropathic pain.
Pronociceptive Actions of Isoflurane
Authors: Flood Pamela , Daniel Danette
Published: November 2003

Background

Low concentrations of inhaled anesthetics present in the early postoperative period can increase pain sensitivity. Changes in pain threshold associated with inhaled anesthetics have been reported in male mice, rats, and humans.

Methods

The authors compared the pain-enhancing effects of isoflurane in male and female mice in response to a thermal stimulus and studied the consequences of hormonal manipulation.

Results

Isoflurane produced a larger increase in pain sensitivity in female mice. Both castration and oophorectomy resulted in an increase in baseline pain sensitivity and potentiated pain enhancement by isoflurane. At stages of the estrus cycle when estrogen was low, female mice showed greater pain enhancement from isoflurane than at high estrogen stages. Treatment with exogenous estrogen reduced isoflurane-induced pain sensitivity. Exogenous testosterone treatment had a similar effect, which did not occur when enzymatic conversion to estrogen was prevented.

Conclusions

Because both estrogen and testosterone reduce the pronociceptive action of isoflurane, intact females may exhibit a larger increase in pain sensitivity because of their cyclical estrogen levels. Testosterone is effective in the male because of conversion to estrogen. Enhanced pain sensitivity is clearly undesirable in the postoperative setting. If these findings also apply to humans, the menstrual cycle may be an important factor in determining pain levels after emergence from general anesthesia.
Risk Factors for Clinically Relevant Pulmonary Embolism and Deep Venous Thrombosis in Patients Undergoing Primary Hip or Knee Arthroplasty
Authors: Mantilla Carlos B. , Horlocker Terese T. , Schroeder Darrell R. , Berry Daniel J. , Brown David L.
Published: November 2003

Background

Prevention of thromboembolic complications after elective lower extremity arthroplasty has increasingly relied on routine thromboprophylaxis in all patients. Not all patients are at equal risk, however, and prophylaxis is not devoid of complications. The aim of this study was to examine the risk factors for clinically relevant pulmonary embolism and deep venous thrombosis after elective primary hip or knee arthroplasty in a large patient population.

Methods

During the 10-yr study period, 116 of 9,791 patients undergoing primary hip or knee arthroplasty at the authors' institution who experienced pulmonary embolism or deep venous thrombosis within 30 days of surgery were matched at a 1:1 ratio with patients undergoing the same surgery with the same surgeon who did not experience an adverse event. Medical records were reviewed, with data abstracted using a standardized data collection form.

Results

Increased body mass index (P = 0.031; odds ratio = 1.5 for each 5-kg/m2 increase) and American Society of Anesthesiologists physical status classification of 3 or greater (P = 0.005; odds ratio = 2.6) were found to independently increase the likelihood of pulmonary embolism or deep venous thrombosis. In addition, use of antithrombotic prophylaxis was found to decrease the likelihood of these thromboembolic events (P = 0.050; odds ratio = 0.2 for aspirin or subcutaneous heparin, and odds ratio = 0.4 for warfarin or low-molecular-weight heparin).

Conclusions

In patients undergoing primary elective lower extremity arthroplasty, obesity, poor American Society of Anesthesiologists physical status classification, and lack of thromboprophylaxis are independent risk factors for clinically relevant thromboembolic events.
Prospective, Randomized Trial Comparing General with Spinal Anesthesia for Cesarean Delivery in Preeclamptic Patients with a Nonreassuring Fetal Heart Trace
Authors: Dyer Robert A. , Els Ilse , Farbas Josef , Torr Gregory J. , Schoeman Leann K. , James Michael F.
Published: November 2003

Background

There are no randomized studies on neonatal outcome after spinal versus general anesthesia for cesarean delivery in preeclamptic patients with a nonreassuring fetal heart trace. This study examined both markers of neonatal hypoxia and maternal hemodynamics.

Methods

Seventy patients were randomized to general (n = 35) or spinal anesthesia (n = 35). The general anesthesia group received thiopentone, magnesium sulfate, and suxamethonium intravenously before intubation, followed by 50% nitrous oxide in oxygen, 0.75-1.5% isoflurane, and morphine after delivery. The target end-tidal partial pressure of carbon dioxide (Pco2) was 30-34 mmHg. The spinal anesthesia group received 1.8 ml hyperbaric bupivacaine plus 10 microg fentanyl at the L3-L4 interspace. Heart rate and blood pressure were measured at specific time points. Hypotension was treated with ephedrine. Maternal arterial and neonatal umbilical arterial blood gas samples were taken at delivery. Resuscitation requirements were recorded.

Results

In both groups, hemodynamic measures remained within acceptable limits. Spinal anesthesia patients required more ephedrine (13.7 vs. 2.7 mg). Maternal Paco2 was lower in the spinal group (28.9 vs. 32.4 mmHg). One-minute Apgar scores were lower after general anesthesia. Base deficit was greater (7.13 vs. 4.68 mEq/l) and neonatal umbilical arterial pH was lower (7.20 vs. 7.23) after spinal anesthesia. Post hoc analysis showed that if maternal diastolic blood pressure on admission was greater than 110 mmHg, neonatal umbilical arterial base deficit was greater after spinal anesthesia. There was no difference in the number of patients with Apgar scores less than 7 at 1 or 5 min or umbilical arterial pH less than 7.2 or in the requirements for resuscitation.

Conclusions

In preeclamptic patients with a nonreassuring fetal heart trace, spinal anesthesia for cesarean delivery was associated with a greater mean neonatal umbilical arterial base deficit and a lower median umbilical arterial pH. The clinical significance remains to be established. Maternal hemodynamics were similar and acceptable with either anesthetic technique.
Urgent Adenotonsillectomy
Authors: Brown Karen A. , Morin Isabelle , Hickey Chantal , Manoukian John J. , Nixon Gillian M. , Brouillette Robert T.
Published: November 2003

Background

The aim of this study was to determine the frequency and type of respiratory complications after urgent adenotonsillectomy (study group) for comparison with a control group of children undergoing a sleep study and adenotonsillectomy for obstructive sleep apnea syndrome. A second aim was to assess risk factors predictive of respiratory complications after urgent adenotonsillectomy.

Methods

The perioperative course of children who underwent adenotonsillectomy between January 1, 1999, and March 31, 2001, was reviewed. Two groups of children were identified from two different databases: the hospital database for surgical procedures (the study group) and the sleep laboratory database (the control group). The retrospective chart review focused on the preoperative status (including an evaluation for obstructive sleep apnea), anesthetic management, and need for postoperative respiratory interventions.

Results

A total of 64 consecutive cases for urgent adenotonsillectomy were identified, and 54 children met the inclusion criteria. Thirty-three children (60%) had postoperative respiratory complications necessitating a medical intervention; 11 (20.3%) required a major intervention (reintubation, ventilation, and/or administration of racemic epinephrine or Ventolin), and 22 (40.7%) required a minor intervention (oxygen administration). Six children (11.1%) required reintubation in the recovery room for respiratory compromise. Risk factors for respiratory complications were an associated medical condition (odds ratio, 8.15; 95% confidence interval, 1.81-36.73) and a preoperative saturation nadir less than 80% (odds ratio, 5.54; 95% confidence interval, 1.15-26.72). Sixteen (49%) of the medical interventions were required within the first postoperative hour. Atropine administration, at induction, decreased the risk of postoperative respiratory complications (odds ratio, 0.18; 95% confidence interval, 0.11-1.050.

Control Group

Of 75 children who underwent a sleep study and adenotonsillectomy, 44 had sleep apnea and were admitted to hospital after elective adenotonsillectomy. Sixteen (36.4%) children had postoperative respiratory complications necessitating a medical intervention. Six percent of the children (n = 3) required a major medical intervention. No child required reintubation for respiratory compromise.

Conclusions

Severe obstructive sleep apnea syndrome and an associated medical condition are risk factors for postadenotonsillectomy respiratory complications. Risk reductions strategies should focus on their assessment.
Effects of Subanesthetic Doses of Ketamine on Regional Cerebral Blood Flow, Oxygen Consumption, and Blood Volume in Humans
Authors: Långsjö Jaakko W. , Kaisti Kaike K. , Aalto Sargo , Hinkka Susanna , Aantaa Riku , Oikonen Vesa , Sipilä Hannu , Kurki Timo , Silvanto Martti , Scheinin Harry
Published: November 2003

Background

Animal experiments have demonstrated neuroprotection by ketamine. However, because of its propensity to increase cerebral blood flow, metabolism, and intracranial pressure, its use in neurosurgery or trauma patients has been questioned.

Methods

15O-labeled water, oxygen, and carbon monoxide were used as positron emission tomography tracers to determine quantitative regional cerebral blood flow (rCBF), metabolic rate of oxygen (rCMRO2), and blood volume (rCBV), respectively, on selected regions of interest of nine healthy male volunteers at baseline and during three escalating concentrations of ketamine (targeted to 30, 100, and 300 ng/ml). In addition, voxel-based analysis for relative changes in rCBF and rCMRO2 was performed using statistical parametric mapping.

Results

The mean +/- SD measured ketamine serum concentrations were 37 +/- 8, 132 +/- 19, and 411 +/- 71 ng/ml. Mean arterial pressure was slightly elevated (maximally by 15.3%, P < 0.001) during ketamine infusion. Ketamine increased rCBF in a concentration-dependent manner. In the region-of-interest analysis, the greatest absolute changes were detected at the highest ketamine concentration level in the anterior cingulate (38.2% increase from baseline, P < 0.001), thalamus (28.5%, P < 0.001), putamen (26.8%, P < 0.001), and frontal cortex (25.4%, P < 0.001). Voxel-based analysis revealed marked relative rCBF increases in the anterior cingulate, frontal cortex, and insula. Although absolute rCMRO2 was not changed in the region-of-interest analysis, subtle relative increases in the frontal, parietal, and occipital cortices and decreases predominantly in the cerebellum were detected in the voxel-based analysis. rCBV increased only in the frontal cortex (4%, P = 0.022).

Conclusions

Subanesthetic doses of ketamine induced a global increase in rCBF but no changes in rCMRO2. Consequently, the regional oxygen extraction fraction was decreased. Disturbed coupling of cerebral blood flow and metabolism is, however, considered unlikely because ketamine has been previously shown to increase cerebral glucose metabolism. Only a minor increase in rCBV was detected. Interestingly, the most profound changes in rCBF were observed in structures related to pain processing.
Reversal of Neuromusclar Blockade and Simultaneous Increase in Plasma Rocuronium Concentration after the Intravenous Infusion of the Novel Reversal Agent Org 25970
Authors: Epemolu Ola , Bom Anton , Hope Frank , Mason Rona
Published: November 2003

Background

The purpose of this study was to determine the changes in the plasma concentration of rocuronium and the reversal of its neuromuscular blockade after the intravenous infusion of Org 25969, the novel neuromuscular block-reversal agent, in anesthetized guinea pigs.

Methods

Rocuronium was infused for 1 h at a rate of 12-19 nmol.kg-1.min-1 to produce a steady-state 90% neuromuscular block. After 30 min, a concomitant infusion of either the reversal agent Org 25969 at a rate of 50 nmol.kg-1.min-1 or an infusion of an equivalent volume of saline was started. The time course of plasma concentrations of rocuronium was determined by use of liquid chromatography-mass spectrometry/mass spectrometry.

Results

In both treatment groups, a steady-state plasma concentration of rocuronium was obtained after 30 min. In the saline-treated group, the plasma concentration of rocuronium and depth of block remained constant. In the Org 25969 group, neuromuscular block was reversed while the rocuronium infusion was ongoing. Simultaneously, an increase in the total plasma concentration of rocuronium (free and complexed) was observed, even though the infusion rate of rocuronium was not changed. Compared with the saline-treated group, a small increase in the postmortem bladder concentration of rocuronium was detected.

Conclusions

The authors propose that the capture of rocuronium by Org 25969 causes the rapid reversal of neuromuscular block. The reversal can be explained by the rapid transfer of free rocuronium from the effect compartment (neuromuscular junction) to the central compartment, in which it is bound to Org 25969. This explains the increase in total plasma concentration of rocuronium (free and bound to Org 25969).
Bacterial Reduction by Cell Salvage Washing and Leukocyte Depletion Filtration
Authors: Waters Jonathan H. , Tuohy Marion J. , Hobson Donna F. , Procop Gary
Published: November 2003

Background

Blood conservation techniques are being increasingly used because of the increased cost and lack of availability of allogeneic blood. Cell salvage offers great blood savings opportunities but is thought to be contraindicated in a number of areas (e.g., blood contaminated with bacteria). Several outcome studies have suggested the safety of this technique in trauma and colorectal surgery, but many practitioners are still hesitant to apply cell salvage in the face of frank bacterial contamination. This study was undertaken to assess the efficacy of bacterial removal when cell salvage was combined with leukocyte depletion filtration.

Methods

Expired packed erythrocytes were obtained and inoculated with a fixed amount of a stock bacteria (Escherichia coli American Type Culture Collections [ATCC] 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, or Bacteroides fragilis ATCC 25285) in amounts ranging from 2,000 to 4,000 colony forming units/ml. The blood was processed via a cell salvage machine. The washed blood was then filtered using a leukocyte reduction filter. The results for blood taken during each step of processing were compared using a repeated-measures design.

Results

Fifteen units of blood were contaminated with each of the stock bacteria. From the prewash sample to the postfiltration sample, 99.0%, 99.6%, 100%, and 97.6% of E. coli, S. aureus, P. aeruginosa, and B. fragilis were removed, respectively.

Discussion

Significant but not complete removal of contaminating bacteria was seen. An increased level of patient safety may be added to cell salvage by including a leukocyte depletion filter when salvaging blood that might be grossly contaminated with bacteria.
Ca2+- and Myosin Phosphorylation–independent Relaxation by Halothane in K+-depolarized Rat Mesenteric Arteries
Authors: Tsuneyoshi Isao , Zhang Dongya , Boyle Walter A.
Published: November 2003

Background

Volatile anesthetics inhibit vascular smooth muscle contraction, but the mechanisms responsible are uncertain. In this study, the effects of halothane on Ca2+ signaling and Ca2+ activation of contractile proteins were examined in high K+-depolarized smooth muscle from rat mesenteric resistance arteries.

Methods

Vessels were cannulated and held at a constant transmural pressure (40 mmHg). Image analysis and microfluorimetry were used to simultaneously measure vessel diameter and smooth muscle intracellular [Ca2+] concentration ([Ca2+]i). Myosin light chain (MLC) phosphorylation was measured using the Western blotting technique.

Results

Step increases in extracellular [Ca2+] concentration (0-10 mM) in high K+ (40 mM)-depolarized smooth muscle produced incremental increases in [Ca2+]i, MLC phosphorylation, and contraction. Halothane (0.5-4.5%) inhibited contraction in a concentration-dependent manner, but the decrease in [Ca2+]i was small, and there was a marked shift in the [Ca2+]i-contraction relationship to the right, indicating an important Ca2+ desensitizing effect. Halothane (0.5-4.5%) did not affect MLC phosphorylation or the [Ca2+]-MLC phosphorylation relationship, but the MLC phosphorylation-contraction relationship was also shifted rightward, indicating an "MLC phosphorylation" desensitizing effect. In contrast, control relaxations produced by the Ca2+ channel blocker nifedipine were accompanied by decreases in both [Ca2+]i and MLC phosphorylation, and nifedipine had no affect on the [Ca2+]i-contraction, [Ca2+]i-MLC phosphorylation, and MLC phosphorylation-contraction relationships.

Conclusions

In high K+-depolarized vascular smooth muscle, halothane relaxation is largely mediated by a Ca2+ and MLC phosphorylation desensitizing effect. These results suggest that the relaxing action of halothane is independent of the classic Ca2+-induced myosin phosphorylation contraction mechanism.
Thoracic Epidural Anesthesia Attenuates Hemorrhage-induced Impairment of Intestinal Perfusion in Rats
Authors: Adolphs Jörn , Schmidt Diego K. , Mousa Shaaban A. , Kamin Britta , Korsukewitz Ines , Habazettl Helmut , Schäfer Michael , Welte Martin
Published: November 2003

Background

During hemorrhagic hypotension, sympathetic vasoconstriction crucially contributes to gut mucosal damage. Sympathetic blockade by thoracic epidural anesthesia has been shown to increase mucosal microvascular perfusion and to improve survival after severe hemorrhage in laboratory animals. This study investigates the effects of thoracic epidural anesthesia on intestinal microvascular perfusion during hemorrhagic hypotension in rats.

Methods

In 32 anesthetized Sprague-Dawley rats either lidocaine 2% (thoracic epidural anesthesia) or normal saline (control) was infused via thoracic epidural catheters. Hemorrhagic hypotension (mean arterial pressure 30 mmHg for 60 min) was induced by withdrawal of blood, which was subsequently retransfused for resuscitation. Functional capillary density and erythrocyte velocity in the mucosa and muscularis were determined by intravital microscopy. Leukocyte-endothelium interaction was studied in postcapillary venules and sympathetic nerve fibers of the intestinal wall were identified by immunohistochemistry.

Results

During hypotension functional capillary density was significantly (P < 0.001) lower in the muscularis of the control group (median [25/75 percentile]: -46.5% [-59.6/-20.8%] change from baseline) as compared with animals that received thoracic epidural anesthesia (-6.1% [-13.4/1.1%]). There were no differences in erythrocyte velocity between groups throughout the experiment. Leukocyte rolling increased significantly (P < 0.001) after resuscitation in control (12 [6/15] vs. baseline 2.5 [1/8]) but not in thoracic epidural anesthesia (4 [2.3/7] vs. baseline: 5 [3/15.5]). Sympathetic nerve fibers were identified in the muscularis and submucosa but not in the mucosa.

Conclusions

During hemorrhagic hypotension and after resuscitation, thoracic epidural anesthesia has beneficial effects on intestinal microvascular perfusion. Because of blockade of sympathetic nerves, thoracic epidural anesthesia prevents perfusion impairment of the muscularis during hypotension and attenuates leukocyte rolling after resuscitation.
Analgesic Efficacy of Inhaled Morphine in Patients after Bunionectomy Surgery
Authors: Thipphawong John B. , Babul Najib , Morishige Richard J. , Findlay Hugh K. , Reber Keith R. , Millward Gary J. , Otulana Babatunde A.
Published: November 2003

Background

The AERx Pain Management System (Aradigm Corporation, Hayward, CA) is a novel pulmonary delivery system for the systemic administration of morphine. The authors compared the relative analgesic efficacy and safety of the AERx Pain Management System with those of placebo and intravenous morphine in an orthopedic postsurgical pain model.

Methods

Eighty-nine male and female PS-1 to PS-3 patients underwent standardized bunionectomy surgery and received multiple doses of inhaled or intravenous placebo, inhaled morphine (one inhalation [2.2 mg] or three inhalations [6.6 mg]), or intravenous morphine (4 mg) in a blinded fashion. Open-label rescue morphine (2 mg) was also available as needed. Pain intensity, pain relief, and time to pain relief were measured after the first dose. Global evaluation, morphine consumption, vital signs, and adverse events were monitored for 8 h after treatment. Blinded study personnel performed all treatment administrations and pain assessments.

Results

Three inhalations of morphine and 4 mg intravenous morphine provided comparable single- and multiple-dose analgesia. One inhalation of morphine was statistically indistinguishable from placebo. Three inhalations of morphine and 4 mg intravenous morphine both consistently demonstrated significantly greater analgesic efficacy than did placebo and one inhalation of morphine.

Conclusions

Comparable analgesic efficacy was demonstrated between a carefully matched dose of inhaled and intravenous morphine in a postsurgical pain model.
Effect of Auditory Evoked Potential Index Monitoring on Anesthetic Drug Requirements and Recovery Profile after Laparoscopic Surgery
Authors: Recart Alejandro , White Paul F. , Wang Agnes , Gasanova Irina , Byerly Stephanie , Jones Stephanie B.
Published: November 2003

Background

The auditory evoked potential (AEP) monitor provides an electroencephalogram-derived index (AAI) that has been reported to correlate with the central nervous system depressant effects of anesthetic drugs. This clinical utility study was designed to test the hypothesis that AAI-guided administration of the maintenance anesthetics and analgesics would improve their titration and thereby provide a faster recovery from general anesthesia.

Methods

Seventy consenting patients undergoing elective general surgery procedures were randomly assigned to either a control (standard clinical practice) or AEP-monitored group. Although the AEP monitor was connected to all patients, the information from the monitor was only made available to the anesthesiologists assigned to patients in the AEP-monitored group. In the AEP-monitored group, the inspired desflurane concentration was titrated to maintain an AAI value of 15-20. In the control group, the inspired desflurane concentration was varied based on standard clinical signs. The AAI values and hemodynamic variables, as well as end-tidal desflurane concentrations, were recorded at 3- to 5-min intervals. The recovery times to achieve a White fast-track score greater than 12 and an Aldrete score of 10, as well as the actual duration of the PACU stay, were evaluated at 5- to 10-min intervals. Patient satisfaction with recovery from anesthesia was assessed using a 100-point verbal rating scale at 24 h after surgery.

Results

The average intraoperative AAI value in the AEP-monitored group was significantly higher than in the control group (16 +/- 5 vs. 11 +/- 8, P < 0.05). Use of the AEP monitor reduced the desflurane requirement by 26% compared to the control group (P < 0.01). In addition, the AEP-monitored group received less intraoperative fentanyl (270 +/- 120 vs. 390 +/- 203 microg, P < 0.05) and more rapidly achieved fast-track eligibility (29 +/- 19 vs. 56 +/- 41 min, P < 0.05). The time required to achieve an Aldrete score of 10 (60 +/- 31 vs. 98 +/- 55 min) and the duration of stay in the recovery room (78 +/- 32 vs. 106 +/- 54 min) were also significantly reduced in the AEP-monitored (vs. control) group (P < 0.05).

Conclusion

Use of AEP monitoring as an adjunct to standard clinical monitors improved titration of anesthetic drugs, thereby facilitating the early recovery process after laparoscopic surgery.
Sevoflurane Provides Greater Protection of the Myocardium than Propofol in Patients Undergoing Off-pump Coronary Artery Bypass Surgery
Authors: Conzen Peter F. , Fischer Susanne , Detter Christian , Peter Klaus
Published: November 2003

Background

Sevoflurane, like other halogenated anesthetics, has been shown to have a protective effect on the myocardium at risk after an ischemic injury. The current study tested the hypothesis that such beneficial effects, so far mainly seen in the laboratory, are reproducible in humans.

Methods

After institutional review board approval, 20 patients scheduled to undergo elective off-pump coronary artery bypass surgery were randomized to receive general anesthesia with either sevoflurane or propofol. Except for this, anesthetic and surgical management was the same in both groups. For assessing myocardial injury, troponin I and myocardial fraction of creatine kinase were determined during the first 24 postoperative hours. Systemic hemodynamic variables were measured before, during, and after completion of coronary artery bypass.

Results

Troponin I concentrations increased significantly more in propofol-anesthetized patients than in patients anesthetized with sevoflurane.

Conclusion

Patients receiving sevoflurane for off-pump coronary artery surgery had less myocardial injury during the first 24 postoperative hours than patients receiving propofol. The results further support cardioprotective effects of sevoflurane.
Total Oxygen Uptake with Two Maximal Breathing Techniques and the Tidal Volume Breathing Technique
Authors: Pandit Jaideep J. , Duncan Thomas , Robbins Peter A.
Published: November 2003

Background

Three common methods for preoxygenation are 3 min of tidal breathing, four deep breaths taken within 30 s (4DB), and eight deep breaths taken within 60 s (8DB). This report compares these three techniques in healthy volunteers.

Methods

Five healthy subjects breathed through a mouthpiece and wore a nose clip; oxygen was delivered at 180 l/min via a low-resistance T-piece. Each subject repeated each of the three oxygenation techniques four times. The end-tidal fraction of oxygen was measured, and the oxygen uptake at the mouth was measured breath by breath. The additional difference between oxygen uptake at the mouth during the period of breathing oxygen (as compared with that during air breathing) was taken to represent the total oxygen sequestrated into body stores.

Results

The mean +/- SD maximum end-tidal fraction of oxygen after the 4DB method was 0.83 +/- 0.09, which was significantly less than either after the 3-min method (0.92 +/- 0.01; P < 0.04) or after the 8DB method (0.91 +/- 0.04; P < 0.03). The mean additional oxygen taken up during oxygenation with the 4DB method was 1.67 +/- 0.45 l, which was significantly lower than with the 3-min method (2.23 +/- 0.85 l; P < 0.04) or with the 8DB method (2.53 +/- 0.74 l; P < 0.01). There were no significant differences for these variables between the 3-min and 8DB methods.

Conclusions

For the physiologic measurements that were made, both the 3-min and the 8DB method are superior to the 4DB method. The 3-min and 8DB methods seem to be equally effective.