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Regional anesthesia and pain medicine 11/2012; 37(6):574-6. · 4.16 Impact Factor
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ABSTRACT: Postoperative nausea and vomiting is a major challenge in the perioperative setting. The incidence can be as high as 80 percent, and the majority of the symptoms among outpatients occur after discharge. This study evaluated the efficacy of a neurokinin-1 receptor antagonist (aprepitant) in reducing postoperative symptoms for up to 48 hours in patients undergoing outpatient plastic surgery.
A prospective, double-blinded, randomized, two-arm evaluation of 150 ambulatory plastic surgery patients receiving a standardized general anesthetic, including postoperative nausea and vomiting prophylaxis with ondansetron and either aprepitant or placebo, was performed. The main outcome measures were the occurrence of vomiting and the severity of nausea for up to 48 hours postoperatively.
Overall, 9.3 percent of patients who received aprepitant versus 29.7 percent in group B had vomiting, with the majority of vomiting episodes occurring after hospital discharge. The Kaplan-Meier plot of the hazards of vomiting revealed an increased incidence of emesis in patients receiving ondansetron alone compared with the combination of ondansetron and aprepitant (p = 0.006). The incidence of nausea was not significantly different in the two groups. Severity of nausea, however, was significantly higher in those receiving ondansetron alone compared with those receiving ondansetron and aprepitant, as measured by a peak nausea score (p = 0.014) and by multivariate analysis of variance results comparing repeated verbal rating scale scores over 48 hours after surgery (p = 0.024).
In patients undergoing plastic surgery, the addition of aprepitant to ondansetron significantly decreases postoperative vomiting rates and nausea severity for up to 48 hours postoperatively.
Therapeutic, II.
Plastic and reconstructive surgery 02/2012; 129(2):519-26. · 2.74 Impact Factor
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ABSTRACT: Respiratory motion and capnometry monitoring were performed during blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) of the brain while a series of paced hyperventilation tasks were performed that caused significant hypocapnia. Respiration volume per time (RVT) and end-tidal carbon dioxide (ETCO(2)) were determined and compared for their ability to explain BOLD contrast changes in the data. A 35% decrease in ETCO(2) was observed along with corresponding changes in RVT. A best-fit ETCO(2) response function, with an average initial peak delay time of 12 s, was empirically determined. ETCO(2) data convolved with this response function was more strongly and prevalently correlated to BOLD signal changes than RVT data convolved with the corresponding respiration response function. The results suggest that ETCO(2) better models BOLD signal fluctuations in fMRI experiments with significant transient hypocapnia. This is due to hysteresis in the ETCO(2) response when moving from hypocapnia to normocapnia, compared to moving from normocapnia to hypocapnia.
Magnetic Resonance Imaging 09/2011; 29(9):1186-94. · 1.99 Impact Factor
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ABSTRACT: This study quantified the impact of the well-known physiologic noise correction algorithm RETROICOR applied to a pain functional magnetic resonance imaging (FMRI) experiment at two field strengths: 1.5 and 3.0 T. In the 1.5-T acquisition, there was an 8.2% decrease in time course variance (σ) and a 227% improvement in average model fit (increase in mean R(2)(a)). In the 3.0-T acquisition, significantly greater improvements were seen: a 10.4% decrease in σ and a 240% increase in mean R(2)(a). End-tidal carbon dioxide data were also collected during scanning and used to account for low-frequency changes in cerebral blood flow; however, the impact of this correction was trivial compared to applying RETROICOR. Comparison between two implementations of RETROICOR demonstrated that oversampled physiologic data can be applied by either downsampling or modification of the timing in the RETROICOR algorithm, with equivalent results. Furthermore, there was no significant effect from manually aligning the physiologic data with corresponding image slices from an interleaved acquisition, indicating that RETROICOR accounts for timing differences between physiologic changes and MR signal changes. These findings suggest that RETROICOR correction, as it is commonly implemented, should be included as part of the data analysis for pain FMRI studies performed at 1.5 and 3.0 T.
Magnetic Resonance Imaging 07/2011; 29(6):819-26. · 1.99 Impact Factor
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Journal of ultrasound in medicine: official journal of the American Institute of Ultrasound in Medicine 03/2010; 29(3):505; discussion 506-8. · 1.25 Impact Factor
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Anesthesia and analgesia 12/2009; 109(6):2028; author reply 2028. · 3.08 Impact Factor
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ABSTRACT: Unintended arterial puncture occurs in 2%-4.5% of central venous catheterizations, resulting in arterial injury in 0.1%-0.5% of patients. Routine performance of manometry during catheterization may successfully identify unintended arterial puncture and avoid arterial cannulation and injury.
We conducted a retrospective review of all cases of central venous catheter placement during a 15-yr period after implementation of a safety program requiring mandatory use of manometry to verify venous access. Arterial injuries were defined as unintended arterial cannulations with a 7-French or larger catheter or dilator. Arterial punctures were defined as the unintended placement of an 18-gauge catheter or needle into the artery. Data were reviewed for all arterial injuries during the entire 15-yr period. In addition, data on both arterial puncture and subsequent arterial injury were evaluated during the final year of analysis.
A total of 9348 central venous catheters were placed during the observation period. During the full 15 yr of observation, there were no cases of arterial injury. During the final year of assessment, 511 central venous catheters were placed, with arterial punctures in 28 patients (5%). Arterial puncture was recognized without manometry in 24 cases. Arterial puncture was identified only with manometry in 4 cases, with no incidents of arterial injury.
Consistent use of manometry, to verify venous placement, during central venous catheterization effectively eliminated arterial injury from unintended arterial cannulation during the 15-yr assessment.
Anesthesia and analgesia 05/2009; 109(1):130-4. · 3.08 Impact Factor
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ABSTRACT: Our purpose was to study the effect of semantic priming at varying semantic distances on brain activation during a lexical decision experiment, using functional magnetic resonance imaging (fMRI).
Neuroimaging studies have demonstrated decreased brain activation for primed versus unprimed stimuli in language areas due to semantic priming, suggesting facilitated semantic retrieval. However, the effect of varying semantic distances on brain activation has not been studied. Therefore we examined direct and indirect priming effects on cerebral activation to provide information regarding spread of activation in the semantic network.
Participants were presented with closely, distantly, and unrelated word pairs during fMRI, and asked to make a lexical decision on the second word.
Behavioral measurements demonstrated significant priming effects for all semantic distances. Imaging results showed modulation of brain activation due to different semantic relationships in the left inferior frontal gyrus, bilateral middle frontal gyrus and anterior temporal lobe, and consisted of decreased magnitude of activation when primed stimuli were processed compared with unprimed stimuli, with the greatest effect observed for closely related words.
This study demonstrates graduated effects of semantic priming on fMRI in semantic but not attentional brain regions, contributing to explain how semantic knowledge is organized and retrieved. These findings support the network model for organization of the semantic lexicon.
Cognitive and Behavioral Neurology 01/2007; 19(4):194-201. · 1.34 Impact Factor
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ABSTRACT: We investigated the effects of a single dose of levodopa (L-dopa) on the level and extent of visual cortex activation of subjects with amblyopia and normal subjects using blood oxygenation level-dependent functional magnetic resonance imaging (fMRI).
Six patients with amblyopia and 9 control patients were recruited. A baseline fMRI session was followed by a second session 90 minutes after the dose of L-dopa. Visual stimuli included vertical sinusoidal gratings with spatial frequencies of 1 and 2 cpd that were counterphased at 4 Hz. Stimuli were presented monocularly and binocularly. The fMRI response was characterized by the total volume and the average level of activation within the occipital cortex. An interocular absolute difference (IDIF) was defined in terms of said measures for between-population analysis of monocular data.
After the administration of L-dopa, visual acuity improved significantly ( P = 0.026) from 0.72 +/- 0.21 (mean +/- SD) to 0.64 +/- 0.24 LogMAR in the amblyopic eye, although remaining the same in the dominant eye and in the eyes of control subjects. The response to L-dopa was found to be population-specific, as indicated by a significant treatment-by-population interaction for the volume of activation IDIF ( P = 0.018) measure: subjects with amblyopia exhibited a post-treatment increase in the volume of activation IDIF whereas control subjects showed a less prominent decrease. This post-treatment increase of IDIF in subjects with amblyopia may be explained by the decrease in the volume of activation found for the amblyopic eye after L-dopa ( P = 0.038). No L-dopa-related activation changes were detected for dominant eye or binocular stimulation in the amblyopic group, and no change was detected in control subjects.
L-dopa elicits a population-specific modulation of the fMRI response, namely, a reduced total volume of activation from the amblyopic eye despite improvement in visual acuity.
Journal of American Association for Pediatric Ophthalmology and Strabismus 07/2005; 9(3):216-23. · 1.03 Impact Factor
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ABSTRACT: Several investigations into brain activation caused by pain have suggested that the multiple painful stimulations used in typical block designs may cause attenuation over time of the signal within activated areas. The effect this may have on pain investigations using multiple tasks has not been investigated. The signal decay across a task of four repeating pain stimulations and between two serial pain tasks separated by a 4-min interval was examined to determine whether signal attenuation may significantly confound pain investigations.
The characteristics of the brain activation of six subjects were determined using whole brain blood oxygenation level-dependent functional magnetic resonance imaging on a 1.5-T scanner. Tasks included both tingling and pain induced by transcutaneous electrical stimulation of the median nerve. The average group maps were analyzed by general linear modeling with corrected cluster P values of less than 0.05. The time courses of individual voxels were further investigated by analysis of variance with P values of less than 0.05.
Significant differences between pain and tingling were found in the ipsilateral cerebellum, contralateral thalamus, secondary somatosensory cortex, primary somatosensory cortex, and anterior cingulate cortex. Highly significant signal decay was found to exist across each single pain task, but the signal was found to be restored after a 4-min rest period.
This work shows that serial pain tasks can be used for functional magnetic resonance imaging studies using electrical nerve stimulation as a stimulus, as long as sufficient time is allowed between the two tasks.
Anesthesiology 11/2004; 101(4):960-9. · 5.36 Impact Factor
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ABSTRACT: Clonidine, buprenorphine, dexamethasone, and midazolam (C, B, D, M) have been used to prolong perineural local anesthesia in the absence of data on the influence of these adjuvants on local anesthetic-induced neurotoxicity. Therefore, the impact of these adjuvants on ropivacaine (R)-induced death of isolated sensory neurons was assessed.
The trypan blue exclusion assay was used to assess death of sensory neurons isolated from adult male Sprague-Dawley rats. Drugs were applied, alone or in combination, for 2 or 24 hrs at 37°C.
Neuronal viability was halved by 24-hr exposure to R (2.5 mg/mL), far exceeding the neurotoxicity of C, B, D, or M (at 2-100 times estimated clinical concentrations). Plain M at twice the estimated clinical concentration produced a small but significant increase in neurotoxicity at 24 hrs. After 2-hr exposure, high concentrations of B, C, and M increased the neurotoxicity of R; the combination of R + M killed more than 90% of neurons. Estimated clinical concentrations of C + B (plus 66 μg/mL D) had no influence on (i) R-induced neurotoxicity, (ii) the increased neurotoxicity associated with the combination of R + M, or (iii) the neurotoxicity associated with estimated clinical concentrations of M. There was increased neurotoxicity with 133 μg/mL D combined with R + C + B.
Results with R reaffirm the need to identify ways to mitigate local anesthetic-induced neurotoxicity. While having no protective effect on R-induced neurotoxicity in vitro, future research with adjuvants should address if the C + B + D combination can enable reducing R concentrations needed to achieve equianalgesia (and/or provide equal or superior duration, in preclinical in vivo models).
Regional anesthesia and pain medicine 36(3):225-30. · 4.16 Impact Factor
