bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Heart Failure on Patients Undergoing Major Noncardiac Surgery
Authors: Hammill Bradley G. , Curtis Lesley H. , Bennett-Guerrero Elliott , O'Connor Christopher M. , Jollis James G. , Schulman Kevin A. , Hernandez Adrian F. 
Published: March 2009

Background
Changes in the demographics and epidemiology of patients with cardiovascular comorbidities who undergo major noncardiac surgery require an updated assessment of which patients are at greater risk of mortality or readmission. The authors evaluated short-term outcomes among patients with heart failure, coronary artery disease (CAD), or neither who underwent major noncardiac surgery.

Methods
Patients were aged 65 and older, had Medicare fee-for-service coverage, and underwent 1 of 13 major noncardiac procedures from 2000 through 2004, excluding patients with end-stage renal disease and patients who did not have at least 1 yr of Medicare fee-for-service eligibility before surgery. Main outcome measures were operative mortality and 30-day all-cause readmission.

Results
Of 159,327 procedures, 18% were performed in patients with heart failure and 34% were performed in patients with CAD. Adjusted hazard ratios of mortality and readmission for patients with heart failure, compared with patients with neither heart failure nor CAD, were 1.63 (95% confidence interval, 1.52-1.74) and 1.51 (95% confidence interval, 1.45-1.58), respectively. Adjusted hazard ratios of mortality and readmission for patients with CAD, compared with patients with neither heart failure nor CAD, were 1.08 (95% confidence interval, 1.01-1.16) and 1.16 (95% confidence interval, 1.12-1.20), respectively. These effects were statistically significant. Patients with heart failure were at significantly higher risk for both outcomes compared with patients with CAD.

Conclusions
Elderly patients with heart failure who undergo major surgical procedures have substantially higher risks of operative mortality and hospital readmission than other patients, including those with coronary disease, admitted for the same procedures. Improvements in perioperative care are needed for the growing population of patients with heart failure undergoing major noncardiac surgery.
Isoflurane Differentially Modulates Inhibitory and Excitatory Synaptic Transmission to the Solitary Tract Nucleus
Authors: Peters James H. , McDougall Stuart J. , Mendelowitz David , Koop Dennis R. , Andresen Michael C. 
Published: March 2009

Background
Isoflurane anesthesia produces cardiovascular and respiratory depression, although the specific mechanisms are not fully understood. Cranial visceral afferents, which innervate the heart and lungs, synapse centrally onto neurons within the medial portion of the nucleus tractus solitarius (NTS). Isoflurane modulation of afferent to NTS synaptic communication may underlie compromised cardiorespiratory reflex function.

Methods
Adult rat hindbrain slice preparations containing the solitary tract (ST) and NTS were used. Shocks to ST afferents evoked excitatory postsynaptic currents with low-variability (SEM <200 mus) latencies identifying neurons as second order. ST-evoked and miniature excitatory postsynaptic currents as well as miniature inhibitory postsynaptic currents were measured during isoflurane exposure. Perfusion bath samples were taken in each experiment to measure isoflurane concentrations by gas chromatography-mass spectrometry.

Results
Isoflurane dose-dependently increased the decay-time constant of miniature inhibitory postsynaptic currents. At greater than 300 mum isoflurane, the amplitude of miniature inhibitory postsynaptic currents was decreased, but the frequency of events remained unaffected, whereas at equivalent isoflurane concentrations, the frequency of miniature excitatory postsynaptic currents was decreased. ST-evoked excitatory postsynaptic current amplitudes decreased without altering event kinetics. Isoflurane at greater than 300 mum increased the latency to onset and rate of synaptic failures of ST-evoked excitatory postsynaptic currents.

Conclusions
In second-order NTS neurons, isoflurane enhances phasic inhibitory transmission via postsynaptic gamma-aminobutyric acid type A receptors while suppressing excitatory transmission through presynaptic mechanisms. These results suggest that isoflurane acts through multiple distinct mechanisms to inhibit neurotransmission within the NTS, which would underlie suppression of homeostatic reflexes.
Motor and Somatosensory Evoked Potentials
Authors: Shine Timothy S.J. , Harrison Barry A. , De Ruyter Martin L. , Crook Julia E. , Heckman Michael , Daube Jasper R. , Stapelfeldt Wolf H. , Cherry Kenneth J. , Gloviczki Peter , Bower Thomas C. , Murray Michael J. 
Published: March 2009

Background
Paraplegia is a devastating complication for patients undergoing repair of thoracoabdominal aortic aneurysms. A monitor to detect spinal cord ischemia is necessary if anesthesiologists are to intervene to protect the spinal cord during aortic aneurysm clamping.

Methods
The medical records of 60 patients who underwent thoracoabdominal aortic aneurysm repair with regional lumbar epidural cooling with evoked potential monitoring were reviewed. The authors analyzed latency and amplitude of motor evoked potentials, somatosensory evoked potentials, and H reflexes before cooling and clamping, after cooling and before clamping, during clamping, and after release of aortic cross clamp.

Results
Twenty minutes after the aortic cross clamp was placed, motor evoked potentials had 88% sensitivity and 65% specificity in predicting spinal cord ischemia. The negative predictive value of motor evoked potentials at 20 min after aortic cross clamping was 96%.

Conclusions
Rapid loss of motor evoked potentials or H reflexes after application of the aortic cross clamp identifies a subgroup of patients who are at high risk of developing spinal cord ischemia and in whom aggressive anesthetic and surgical interventions may be justified.
Comparison of Thoracic Epidural Pressure in the Sitting and Lateral Decubitus Positions
Authors: Gil Nam Su , Lee Jong-Hwan , Yoon Seung Z. , Jeon Yunseok , Lim Young Jin , Bahk Jae Hyon 
Published: March 2009

Background
The hanging drop technique identifies the epidural space using the negative pressure of this space. Although the hanging drop technique is popular at the thoracic level, there is still controversy on the negative epidural pressure at this level. The authors hypothesized that the epidural pressure is more consistently negative in the sitting position than in the lateral decubitus position at the thoracic level.

Methods
This study compared the epidural pressures of 28 awake patients in the sitting (sitting group, n = 14) or lateral decubitus (lateral group, n = 14) position. The T5-T6 epidural pressure was measured using a closed pressure measurement system connected to a Tuohy needle.

Results
All of the thoracic epidural pressures in the sitting group were negative (median, -5 mmHg; range, -18 to -1; mean, -7.2; SD, 6.3), in contrast to the lateral group (median, 5 mmHg; range, -4 to 13; mean, 5.1; SD, 4.4). The thoracic epidural pressure in the sitting group was significantly lower than in the lateral group (P < 0.001).

Conclusions
The thoracic epidural pressure is more negative in the sitting position than in the lateral decubitus position. These results suggest that the patient should be sitting when the hanging drop technique is used to identify the epidural space.
Electrophysiologic Characteristics of Large Neurons in Dorsal Root Ganglia during Development and after Hind Paw Incision in the Rat
Authors: Ririe Douglas G. , Liu Baogang , Clayton Bridgette , Tong Chuanyao , Eisenach James C. 
Published: March 2009

Background
Withdrawal thresholds in the paw are lower in younger animals, and incision further reduces these thresholds. The authors hypothesized that these differences result in part from changes in intrinsic electrophysiologic properties of large neurons.

Methods
Using isolated whole dorsal root ganglion, current clamping was performed to determine the electrophysiologic properties of large neurons before and after incision in animals aged 1 and 4 weeks. Mechanical withdrawal thresholds were used to follow paw sensitivity.

Results
After paw incision, withdrawal thresholds decreased to a similar degree at both ages, but returned to control threshold at 72 h only in the 1-week-old animals. The resting membrane potential was less negative and the rheobase and the resistance of the membrane were lower at baseline in the 1-week-old animals (P < 0.05). After incision, the membrane potential became more depolarized and the rheobase was less in both ages. These changes remained 72 h after the incision in both ages.

Conclusion
These findings suggest that lower mechanical thresholds in the younger animals may be partially attributed to the intrinsic electrophysiologic properties of the larger-diameter afferent neurons. The lack of resolution of the electrophysiologic changes in the young despite the resolution of the withdrawal response suggests that continued input from large fibers into the central nervous system may occur at this age despite the apparent resolution of behavioral changes. Further studies are needed to determine the etiology of these differences, their impact in the central nervous system, and whether theses changes can be prevented.
Successful Transtracheal Lung Ventilation Using a Manual Respiration Valve
Authors: Meissner Konrad , Iber Thomas , Roesner Jan-Patrick , Mutz Christian , Wagner Hans-Erich , Layher Christina , Bartels Utz , Gründling Matthias , Usichenko Taras I. , Wendt Michael , Lehmann Christian , Pavlovic Dragan 
Published: March 2009

Background
Lung ventilation through a thin transtracheal cannula may be attempted in patients with laryngeal stenosis or "cannot intubate, cannot ventilate" situations. It may be impossible to achieve sufficient ventilation if the lungs are spontaneously emptying only through the thin transtracheal cannula, which imposes high resistance to airflow, resulting in dangerous hyperinflation. Therefore, the authors describe the use of a manual respiration valve that serves as a bidirectional pump providing not only inflation but also active deflation of the lungs in case of emergency transtracheal lung ventilation.

Methods
The effectiveness of such a valve was tested in vitro using mechanical lungs in combination with two different cannula sizes and various gas flows. The valve was then tested in five pigs using a transtracheal 16-gauge cannula with three different combinations of inspiratory/expiratory times and gas flows and an occluded upper airway.

Results
In the mechanical lungs, the valve permitted higher minute volumes compared with spontaneous lung emptying. In vivo, the arterial oxygen and carbon dioxide partial pressures increased initially and then remained stable over 1 h (arterial oxygen tension, 470.8 +/- 86.8; arterial carbon dioxide tension, 63.0 +/- 7.2 mmHg). The inspiratory pressures measured in the trachea remained below 10 cm H2O and did not substantially influence central venous and pulmonary artery pressures. Mean arterial pressure and cardiac output were unaffected by the ventilation maneuvers.

Conclusions
This study demonstrated in vitro and in vivo in adult pigs that satisfactory lung ventilation can be assured with transtracheal ventilation through a 16-gauge cannula for a prolonged period of time if combined with a bidirectional manual respiration valve.
Enhancement of Spinal N -Methyl-d-aspartate Receptor Function by Remifentanil Action at δ-Opioid Receptors as a Mechanism for Acute Opioid-induced Hyperalgesia or Tolerance
Authors: Zhao Min , Joo Daisy T. 
Published: March 2009

Background
Intraoperative remifentanil infusions have been associated with postoperative opioid-induced hyperalgesia and tolerance. Using a previously identified subpopulation of spinal neurons that displays an augmentation in N-methyl-D-aspartate (NMDA) receptor current after chronic morphine, investigations were undertaken to determine whether remifentanil induces acute increases in NMDA responses that are concentration dependent and receptor subtype dependent.

Methods
Electrophysiologic recordings of NMDA current were made from cultured rat dorsal horn neurons treated with remifentanil at various concentrations for 60 min. Selective mu- or delta-opioid receptor inhibitors and agonists were used to determine the site of action of remifentanil.

Results
Remifentanil at 4, 6, and 8 nM, but not higher or lower concentrations, caused significant mean increases in NMDA peak current amplitude of 37.30% (P < 0.001), 30.19% (P < 0.001), and 23.52% (P = 0.025), respectively, over control conditions. This occurred by 36 min of remifentanil perfusion and persisted throughout its washout. Inhibition by 100 nM naloxone or 1 nM naltrindole attenuated the remifentanil-induced NMDA response increase. Selective delta-opioid agonists [D-Pen(2), D-Pen(5)]enkephalin and deltorphin II displayed a similar bell-shaped concentration-response relation for the enhancement of NMDA responses, and 10 nM deltorphin II occluded the effects of 4 nM remifentanil on NMDA responses.

Conclusions
Clinically relevant concentrations of remifentanil induce rapid, persistent increases in NMDA responses that mirror the development of remifentanil-induced hyperalgesia and tolerance. NMDA enhancement by remifentanil is dependent on the activation of both mu- and delta-opioid receptors and is inducible solely by delta-opioid receptor activation. Therefore, selective delta-opioid inhibition may attenuate acute paradoxical increases in pain and tolerance to opioids.
Anesthetic Technique for Radical Prostatectomy Surgery Affects Cancer Recurrence
Authors: Biki Barbara , Mascha Edward , Moriarty Denis C. , Fitzpatrick John M. , Sessler Daniel I. , Buggy Donal J. 
Published: March 2009

Background
Regional anesthesia and analgesia attenuate or prevent perioperative factors that favor minimal residual disease after removal of the primary carcinoma. Therefore, the authors evaluated prostate cancer recurrence in patients who received either general anesthesia with epidural anesthesia/analgesia or general anesthesia with postoperative opioid analgesia.

Methods
In a retrospective review of medical records, patients with invasive prostatic carcinoma who underwent open radical prostatectomy between January 1994 and December 2003 and had either general anesthesia-epidural analgesia or general anesthesia-opioid analgesia were evaluated through October 2006. The endpoint was an increase in postoperative prostate-specific antigen.

Results
After adjusting for tumor size, Gleason score, preoperative prostate-specific antigen, margin, and date of surgery, the epidural plus general anesthesia group had an estimated 57% (95% confidence interval, 17-78%) lower risk of recurrence compared with the general anesthesia plus opioids group, with a corresponding hazard ratio of 0.43 (95% confidence interval, 0.22-0.83; P = 0.012) in a multivariable Cox regression model. Gleason score and tumor size (percent of prostate involved) were also independent predictors of recurrence (hazards ratios of 1.19 [1.08, 1.52], P = 0.004, and 1.17 [1.03, 1.34] for 10% size difference, P = 0.01, respectively). A similar association between epidural use and recurrence was obtained by comparing patients matched on the propensity to receive epidural versus general anesthesia.

Conclusions
Open prostatectomy surgery with general anesthesia, substituting epidural analgesia for postoperative opioids, was associated with substantially less risk of biochemical cancer recurrence. Prospective randomized trials to evaluate this association seem warranted.
Reversal of Profound, High-dose Rocuronium-induced Neuromuscular Blockade by Sugammadex at Two Different Time Points: An International, Multicenter, Randomized, Dose-finding, Safety Assessor-blinded, Phase II Trial
Authors: Pühringer Friedrich K. , Rex Christopher , Sielenkämper Andreas W. , Claudius Casper , Larsen Per Bo , Prins Martine E. , Eikermann Matthias , Khuenl-Brady Karin S. 
Published: March 2009

Background
Sugammadex (Org 25969), a novel, selective relaxant binding agent, was specifically designed to rapidly reverse rocuronium-induced neuromuscular blockade. The efficacy and safety of sugammadex for the reversal of profound, high-dose rocuronium-induced neuromuscular blockade was evaluated.

Methods
A total of 176 adult patients were randomly assigned to receive sugammadex (2, 4, 8, 12, or 16 mg/kg) or placebo at 3 or 15 min after high-dose rocuronium (1.0 or 1.2 mg/kg) during propofol anesthesia. The primary endpoint was time to recovery of the train-of-four ratio to 0.9. Neuromuscular monitoring was performed using acceleromyography.

Results
Sugammadex administered 3 or 15 min after injection of 1 mg/kg rocuronium decreased the median recovery time of the train-of-four ratio to 0.9 in a dose-dependent manner from 111.1 min and 91.0 min (placebo) to 1.6 min and 0.9 min (16 mg/kg sugammadex), respectively. After 1.2 mg/kg rocuronium, sugammadex decreased time to recovery of train-of-four from 124.3 min (3-min group) and 94.2 min (15-min group) to 1.3 min and 1.9 min with 16 mg/kg sugammadex, respectively. There was no clinical evidence of reoccurrence of neuromuscular blockade or residual neuromuscular blockade. Exploratory analysis revealed that prolongation of the corrected QT interval considered as possibly related to sugammadex occurred in one patient. Another two patients developed markedly abnormal arterial blood pressure after sugammadex that lasted approximately 15 min.

Conclusion
Sugammadex provides a rapid and dose-dependent reversal of profound neuromuscular blockade induced by high-dose rocuronium (1.0 or 1.2 mg/kg) in adult surgical patients.
Remifentanil Modifies the Relation of Electroencephalographic Spectral Changes and Clinical Endpoints in Propofol Anesthesia
Authors: Kortelainen Jukka , Koskinen Miika , Mustola Seppo , Seppänen Tapio 
Published: March 2009

Background
Depth-of-anesthesia monitoring with the electroencephalogram has become widely used in anesthesia practice. Generally, the methods presented are based on the spectral changes of the electroencephalogram. In this study, the authors evaluate the influence of remifentanil on the relation of timely occurrence of clinical endpoints and the spectral behavior of the electroencephalogram.

Methods
Twenty-seven patients scheduled to undergo a surgical procedure were randomly assigned to three groups. Patients blindly received equal volumes of saline or remifentanil (7.5 or 30 microg.kg.h) 1 min before induction of anesthesia with infusion of propofol (30 mg.kg.h). The occurrence of loss of counting, loss of obeying verbal command, and loss of reaction to tetanic stimulation was assessed. The electroencephalogram was recorded from electrode Fz referenced to the common average, and an iterative algorithm was applied to solve the underlying frequency progression pattern. The positions of the clinical endpoints on the pattern were analyzed.

Results
The administration of remifentanil during induction of anesthesia with propofol led to an earlier occurrence of the clinical endpoints on the frequency progression pattern. A significant difference (P < 0.05) was observed between the saline and high-dose patient groups in all three endpoints. The effect of remifentanil was proportional to the infusion rate.

Conclusions
The infusion of remifentanil during propofol anesthesia significantly modifies the mutual relations of the electroencephalographic spectral characteristics and the endpoints in a predictable and quantifiable manner. This finding suggests that the electroencephalographic phenomena and the endpoints may not be identical but rather to some extent separate manifestations of hypnotic drug effect.
Effects of Heme Oxygenase 1 on Brain Edema and Neurologic Outcome after Cardiopulmonary Resuscitation in Rats
Authors: Zhang Bing , Wei Xia , Cui Xiaoguang , Kobayashi Tsutomu , Li Wenzhi 
Published: March 2009

Background
Heme oxygenase 1 (HO-1) has been shown to attenuate neuronal injury. Therefore, the authors examined whether HO-1 would reduce the brain damage caused by cardiac arrest.

Methods
Rats anesthetized with halothane were subjected to 8 min of cardiac arrest by asphyxia without any pretreatment (control group) or pretreated with an inducer of HO-1 (hemin group) or with an inhibitor of HO-1 (tin protoporphyrin group). Then, the animals were resuscitated with a standardized method. Brain water content (1 and 6 h after resuscitation), neurologic deficit score, viable neuronal counts, and caspase-3 immunostaining in the hippocampus (4 and 14 days) were evaluated.

Results
Water content in the hemin group was significantly reduced (mean +/- SD: 83.1 +/- 1.9% for 1 h after resuscitation; P = 0.03) and significantly greater in the tin protoporphyrin group (91.1 +/- 2.0% for 1 h after resuscitation; P = 0.035) when compared with the control group (88.2 +/- 2.4%). Water content of the cortex was nearly the same as that of the hippocampus. Neurologic deficit scores and neuronal survival were significantly better in the hemin group than in the control group on the 4th and 14th days. In rats that survived for 4 days, the amount of caspase 3-positive neurons was 27 +/- 7 in the control group, whereas the value was 14 +/- 6 in the hemin group (P < 0.05).

Conclusions
In rats resuscitated from cardiac arrest, induction of HO-1 by hemin reduced brain edema, improved neurologic outcome, and protected neurons against apoptosis.
Low-dose Propofol–induced Amnesia Is Not due to a Failure of Encoding
Authors: Veselis Robert A. , Pryor Kane O. , Reinsel Ruth A. , Mehta Meghana , Pan Hong , Johnson Ray 
Published: March 2009

Background
Propofol may produce amnesia by affecting encoding. The hypothesis that propofol weakens encoding was tested by measuring regional cerebral blood flow during verbal encoding.

Methods
Seventeen volunteer participants (12 men; aged 30.4 +/- 6.5 yr) had regional cerebral blood flow measured using H2O positron emission tomography during complex and simple encoding tasks (deep vs. shallow level of processing) to identify a region of interest in the left inferior prefrontal cortex (LIPFC). The effect of either propofol (n = 6, 0.9 microg/ml target concentration), placebo with a divided attention task (n = 5), or thiopental at sedative doses (n = 6, 3 microg/ml) on regional cerebral blood flow activation in the LIPFC was tested. The divided attention task was expected to decrease activation in the LIPFC.

Results
Propofol did not impair encoding performance or reaction times, but impaired recognition memory of deeply encoded words 4 h later (median recognition of 35% [interquartile range, 17-54%] of words presented during propofol vs. 65% [38-91%] before drug; P < 0.05). Statistical parametric mapping analysis identified a region of interest of 6.6 cm in the LIPFC (T = 7.44, P = 0.014). Regional cerebral blood flow response to deep encoding was present in this region of interest in each group before drug (T > 4.41, P < 0.04). During drug infusion, only the propofol group continued to have borderline significant activation in this region (T = 4.00, P = 0.063).

Conclusions
If the amnesic effect of propofol were solely due to effects on encoding, activation in the LIPFC should be minimal. Because LIPFC activation was not totally eliminated by propofol, the amnesic action of propofol must be present in other brain regions and/or affect other memory processes.