Biomedical subjects

Rafael Huertas

Publications and source records attributed to Rafael Huertas.

11 recordsLinked to original sources

PubMed2006

Poststroke C-reactive protein is a powerful prognostic tool among candidates for thrombolysis.

BACKGROUND AND PURPOSE: After acute stroke, an increased level of C-reactive protein (CRP) measured at discharge predicts unfavorable outcome. We sought to investigate whether CRP measured before tissue plasminogen activator (tPA) treatments may add prognostic information to guide stroke thrombolysis. METHODS: Our target was 151 consecutive patients with an ischemic stroke involving the middle cerebral artery territory who received tPA within 3 hours of symptom onset. High-sensitivity CRP was measured before tPA administration, and CRP gene polymorphisms were determined (G1059C and C1444T). Functional outcome was evaluated by 3-month modified Rankin Scale (mRS). RESULTS: A total of 143 tPA-treated patients were valid for analyses after exclusion of those with inflammatory diseases and those probably infected (CRP >6 mg/dL). Patients with history of previous stroke, hypertension, or atrial fibrillation had higher levels of CRP (P<0.05). CRP was higher in patients who died after thrombolysis (n=19) than in survivors (0.85 versus 0.53 mg/dL; P=0.002). Among the 94 patients with proximal middle cerebral artery occlusions, CRP level was 0.53 for 81 survivors versus 0.81 mg/dL for 13 who died (P=0.001). CRP-survival association was found even among patients who recanalized by the end of tPA infusion (P=0.007). A correlation between CRP and mRS was found (r=0.36, P=0.02), although CRP polymorphisms were not related to neurological outcome. In a logistic regression model, CRP (odds ratio=8.51; 95% CI, 2.16 to 33.5; P=0.002) and age (odds ratio=6.25; 95% CI, 1.44 to 27.19; P=0.015) were the only baseline mortality predictors. CONCLUSIONS: Admission CRP predicts mortality among tPA-treated stroke patients. Very early recanalization does not ameliorate the negative prognostic impact of elevated CRP.

Aged↗

PubMed2006

Disinfecting solutions for soft contact lenses using different color indicators.

PURPOSE: The color change reached in two commercial disinfecting solutions for soft contact lenses using new color indicators has been analyzed, and its relationship with the temporal evolution of the hydrogen peroxide concentration, responsible for the disinfection process, has been examined. The results are compared with another commercial solution using a different color indicator. METHODS: Color measurements of the disinfecting solutions were performed at 2-minute intervals for over 2 hours using a Photo-Research PR-704 spectroradiometer with horizontal optical axis. Samples were placed at the floor of a VeriVide CAC 120 light booth with a Munsell gray mask behind them. Two different standard light sources, representative of outdoor and indoor illumination, were used. The hydrogen peroxide concentration during the disinfection process was measured for each commercial solution using a Beckman DU-7 spectrophotometer. RESULTS: The temporal evolutions of color for the two new disinfecting solutions were qualitatively different. CIELAB color differences induced in these two new disinfecting solutions were 1.5 and 2.2 times greater than that measured in the earlier comparative solution and occur in a more appropriate direction of color space for users with defective color vision. Although the earlier solution generated color changes close to the deutan confusion line, the changes produced by the new solutions are close to the tritan confusion line. After 2 hours, the hydrogen peroxide concentration for the two new solutions was approximately one-third the one reached by the earlier solution. There are statistically significant correlations (p < 0.01) between color change and hydrogen peroxide concentration for the two new solutions (r = -0.878 and r = -0.990). CONCLUSIONS: Color changes in these hydrogen peroxide systems can be used as a safe and useful tool by contact lens wearers. The two new disinfecting solutions analyzed in this article show noteworthy improvements over the earlier solution.

Color↗

PubMed2006

Influence of random-dot textures on perception of suprathreshold color differences.

We have analyzed the way in which simulated textures made of random dots influence visual suprathreshold color tolerances. We considered 32 textures created by a systematic variation of the following variables: size, number, and color of the dots. Each texture was mapped on the five centers recommended by the International Commission on Illumination (CIE) in 1978 [Color Res. Appl.3, 149 (1978)]. A panel of five experienced observers determined the experimental tolerances using a CRT color monitor by the method of adjustment. At our observation distance, neither small differences in dot size (1 or 4 pixels) nor sparse number of dots (less than 20% of the surface of the sample) changed the tolerances found for homogeneous samples. For the textures that led to statistically significant differences with respect to homogeneous samples, the parametric factors of CIEDE2000 and CIE94 color-difference formulas were fitted. These simulated textures consistently reduced the color difference perceived in a pair or, equivalently, increased the tolerances, mainly (but not only) lightness tolerance. The results demonstrate that it is not simple to provide a unique set of parametric factors for all the potential textures.

Color↗

PubMed2006

Performance of a color-difference formula based on OSA-UCS space using small-medium color differences.

An investigation of the color metrics and the complexity of the CIEDE2000 formula shows that CIELAB space is inadequate to represent small-medium color differences. The OSA-UCS (Uniform Color Space) Committee has shown that no space with uniform scale for large color differences exists. Therefore the practical way for color-difference specification is a color-difference formula in a nonuniform space. First, the BFD (Bradford University) ellipses are considered in the OSA-UCS space, and their very high regularity suggests a new and very simple color-difference formula at constant luminance. Then the COM (combined) data set used for the development of the CIEDE2000 formula is considered in the OSA-UCS space, and the color-difference formula is extended to sample pairs with a different luminance factor. The value of the performance factor PF/3 for the proposed OSA-UCS-based formula shows that the formula performs like the more complex CIEDE2000 formula for small-medium color differences.

Algorithms↗

PubMed2005

Microbubble administration accelerates clot lysis during continuous 2-MHz ultrasound monitoring in stroke patients treated with intravenous tissue plasminogen activator.

BACKGROUND AND PURPOSE: We sought to evaluate the effects of administration of microbubbles (MBs) on the beginning, speed, and degree of middle cerebral artery (MCA) recanalization during systemic thrombolysis and continuous 2-MHz pulsed-wave transcranial Doppler (TCD) monitoring. METHODS: We evaluated 111 patients with acute stroke attributable to MCA occlusion treated with intravenous tissue plasminogen activator (tPA). Thirty-eight patients were treated with tPA plus continuous 2-hour TCD monitoring plus 3 doses of 2.5 g (400 mg/mL) of galactose-based MBs given at 2, 20, and 40 minutes after tPA bolus (MB group). These patients were compared with 73 patients who were allocated to receive tPA plus continuous 2-hour TCD ultrasound (US) monitoring (tPA/US group) or tPA plus placebo monitoring (tPA group), most of whom were enrolled in a previous study of US-enhanced thrombolysis. The beginning, degree, and time to maximum completeness of recanalization during the first 2 hours of tPA bolus were recorded. RESULTS: Median prebolus National Institutes of Health Stroke Scale (NIHSS) score was 18. Eighty patients (72%) had a proximal and 31 (28%) a distal MCA occlusion on TCD. Thirty-seven patients (33%) received tPA/US, 38 (34%) received tPA/US/MB, and 36 (32%) were treated with tPA alone. Stroke severity, time to treatment, location of MCA occlusion, and presence of carotid artery disease were similar among groups. Two-hour recanalization was seen in 14 (39%), 25 (68%), and 27 patients (71%) in the tPA, tPA/US, and tPA/US/MB groups, respectively (P=0.004). Two-hour complete recanalization rate was significantly (P=0.038) higher in the tPA/US/MB group (54.5%) compared with tPA/US (40.8%) and tPA (23.9%) groups. The time to beginning of recanalization after tPA bolus was 26+/-18 minutes in the tPA/US group and 19+/-12 minutes in the tPA/US/MB group (P=0.12). Four patients (3.6%) experienced symptomatic intracranial hemorrhage: 2 (5.5%), 1 (2.7%), and 1 patient (2.6%) who received tPA only, tPA/US, and tPA/US/MB, respectively, experienced symptomatic intracranial hemorrhage. At 24 hours, 31%, 41%, and 55% of tPA, tPA/US, and tPA/US/MB improved >4 points in the NIHSS score. CONCLUSIONS: Administration of MBs induces further acceleration of US-enhanced thrombolysis in acute stroke, leading to a more complete recanalization and to a trend toward better short- and long-term outcome.

Adult↗

PubMed2005

Predictors of early arterial reocclusion after tissue plasminogen activator-induced recanalization in acute ischemic stroke.

BACKGROUND AND PURPOSE: We aimed to determine clinical and hemodynamic predictors of early reocclusion (RO) in stroke patients treated with intravenous tissue plasminogen activator (tPA). METHODS: We studied 142 consecutive stroke patients with a documented middle cerebral artery (MCA) occlusion treated with intravenous tPA. All patients underwent carotid ultrasound and transcranial Doppler (TCD) examination before tPA bolus. National Institutes of Health Stroke Scale (NIHSS) scores were performed at baseline and serially for <24 hours. TCD monitoring of MCA recanalization (RE) and RO was performed during the first 2 hours after tPA bolus and repeated when clinical deterioration occurred <24 hours after documented RE in absence of intracranial hemorrhage. RESULTS: After 1 hour of tPA administration, RE occurred in 84 (61%) patients (53 partial, 31 complete). Of these, 21 (25%) patients worsened after an initial improvement and 17 (12%) of them showed RO on TCD. RO was identified at a mean time of 65+/-55 minutes after documented RE. RO was associated (P=0.034) with a lower degree of 24-hour NIHSS score improvement than sustained RE, and a higher modified Rankin scale score at 3 months (P=0.002). Age older than 75 years (P=0.012), previous antiplatelet treatment (P=0.048), baseline NIHSS score >16 points (P=0.009), higher leukocytes count (P=0.042), beginning of RE <60 minutes after tPA bolus (P=0.039), and ipsilateral severe carotid stenosis/occlusion (P=0.001) were significantly associated with RO. In a logistic regression model, NIHSS score >16 at baseline (odds ratio [OR], 7.1; 95% CI, 1.3 to 32) and severe ipsilateral carotid disease (OR, 13.3; 95% CI, 3.2 to 54) remained as independent predictors of RO. CONCLUSIONS: Stroke severity and ipsilateral severe carotid artery disease independently predict RO after tPA-induced MCA RE.

Adult↗

PubMed2004

Impact of admission hyperglycemia on stroke outcome after thrombolysis: risk stratification in relation to time to reperfusion.

BACKGROUND AND PURPOSE: We evaluated the impact of admission hyperglycemia (HG) on stroke outcome in relation to the timing of reperfusion in patients treated with tissue plasminogen activator (tPA). METHODS: We studied 138 consecutive stroke patients with a documented middle cerebral artery (MCA) occlusion treated with intravenous tPA <3 hours of stroke onset. Serum glucose was determined at baseline before tPA administration. HG was defined as a glucose level >140 mg/dL. National Institutes of Health Stroke Scale (NIHSS) scores were obtained at baseline and 24 hour. Transcranial Doppler monitoring of recanalization was conducted during the first 12 hour of stroke onset. mRS was used to assess outcome at 3 months. RESULTS: Median baseline NIHSS score was 17 points. At baseline, 42 (37.3%) patients were hyperglycemic and 96 (62.7%) normoglycemic. Reperfusion was achieved <3 hours of stroke onset in 32 (23%) patients, between 3 to 6 hours in 49 (36%), 6 to 12 hours in 15 (12%), and in 32 (23%) the MCA remained occluded at 12 hours. A logistic regression model revealed that baseline NIHSS score >16 points (odds ratio [OR], 3.32; 95% CI, 2.18 to 24.7; P=0.032) and admission glucose level >140 mg/dL (OR, 5.65; 95% CI, 1.97 to 16.18; P=0.002) independently predicted poor outcome (modified Rankin scale, 3 to 6) at 3 months. After adjusting by age, stroke severity, site of MCA occlusion, and degree of recanalization, the contribution of HG for poor outcome was higher as shorter the time to reperfusion. The highest odds for poor outcome related to HG corresponded to patients who recanalized <3 hour (OR, 3.1; 95% CI, 1.8 to 14.3; P=0.002), as compared with those who recanalized between 3 and 6 hours (OR, 2.1; 95% CI, 1.1 to 16; P=0.034) and between 6 to 12 hours (OR, 1.1; 95% CI, 0.7 to 21; P=0.43). Moreover, baseline glucose level was negatively correlated (r=-0.45; P=0.001) with the degree of improvement in the NIHSS score at 24 hours after early (<3 hours) but not after delayed (>3 hours) or no recanalization. CONCLUSIONS: The impact of admission HG on stroke outcome varies depending on the time to tPA-induced reperfusion. The detrimental effect of acute HG is higher after early than after delayed or no reperfusion. Ultra-early glycemic control before reperfusion may improve the efficacy of thrombolytic therapy.

Adult↗

PubMed2004

[Clinical benefit following the implementation of a specialized urgent stroke care system].

BACKGROUND AND OBJECTIVE: Several strategies as stroke teams, stroke code teams, or stroke units development have demonstrated to improve stroke care quality. The potential benefit of implementing them as a whole has not been studied. We aimed to test the clinical efficacy of a specialized and urgent stroke assistance system in a University Hospital, as well as the specific impact of each part of the system on several clinical indicators. PATIENTS AND METHOD: The implementation of the system followed three consecutive steps: stroke team and stroke code development, stroke unit creation and finally on-call stroke neurologists incorporation. Several clinical indicators to evaluate results have been selected. We compared data available before system onset (1992-1997) with data obtained during the system implementation (1998-2002). Modification in the results indicators following each of the individual steps of the system was also evaluated. RESULTS: During the five years of the system implementation, 5843 stroke patients have been prospectively studied. Admission and readmission necessities were reduced up to 34.2% and 81.8% respectively. Length of stay progressively decreased from 18 (pre-1998) to 7 days (2002). In-hospital mortality and institutionalization necessities were reduced to 50.1% and 50.5% respectively. The third step, in which on-call stroke neurologist were incorporated to the system, has demonstrated to be the most efficient in decreasing the length of stay, hospital mortality and institutionalization necessities. CONCLUSIONS: The creation of a specialized urgent stroke care system, protocol based and developed in stroke units, improves the medical assistance quality for stroke patients. Stroke neurologists on-call have a relevant role in the system working.

Aged↗

PubMed2004

Relative significance of the terms in the CIEDE2000 and CIE94 color-difference formulas.

CIELAB-based color-difference formulas are used to improve the prediction of visually perceived color differences through the introduction of various corrections to CIELAB. In our study we analyze the relative importance of these corrections. From the combined dataset employed for the development of CIEDE2000, we found that the improvement of CIE94 over CIELAB was considerably greater than that of CIEDE2000 over CIE94. Chroma-difference correction was the most important correction in both CIE94 and CIEDE2000. With an arbitrary value of 100 assigned to this correction, the score of the hue-difference correction in CIE94 was 21, and the scores of the four remaining corrections in CIEDE2000 were as follows: hue difference, 29; rotation term, 8; lightness difference, 8; and gray correction, 6. At 95% confidence level each of the corrections introduced in CIEDE2000 or CIE94 was statistically significant for the whole combined dataset, in agreement with the results reported by CIE TC 1-47 and 1-29. For the combined dataset, the differences between CMC and CIEDE2000 were found to be statistically significant at 95% confidence level, but the differences between CMC and CIE94 were not. From subsets of the combined dataset it was concluded that further analyses of the lightness-difference and gray corrections proposed by CIEDE2000 would be desirable, using new experimental data.

Journal Article↗

PubMed2003

Effects of admission hyperglycemia on stroke outcome in reperfused tissue plasminogen activator--treated patients.

BACKGROUND AND PURPOSE: We sought to investigate the impact of hyperglycemia before reperfusion on long-term outcome in patients treated with intravenous tissue plasminogen activator (tPA). METHODS: Of 268 consecutive patients with a nonlacunar middle cerebral artery (MCA) stroke evaluated at <3 hours after onset, 73 (27.2%) received intravenous tPA. Serum glucose was determined at baseline before tPA administration. Hyperglycemia was defined as a glucose level >140 mg/dL. National Institutes of Health Stroke Scale (NIHSS) scores were obtained at baseline and 24 hours. Transcranial Doppler monitoring of recanalization and reocclusion was conducted during the first 24 hours. Total infarct volume was measured on CT at day 5 to 7. Modified Rankin Scale was used to assess outcome at 3 months. RESULTS: Median NIHSS score was 17. At baseline, 31 patients (42.5%) were hyperglycemic and 42 (57.5%) normoglycemic. Early reperfusion (<6 hours) occurred in 43 patients (58.9%). Admission blood glucose correlated negatively with the degree of neurological improvement at 24 hours in reperfused (r=-0.43; P=0.019) but not in nonreperfused (r=-0.20; P=0.21) tPA-treated patients. Increased age (P=0.014), history of diabetes mellitus (P=0.043), admission glucose >140 mg/dL (P=0.002), and early reocclusion (P=0.004) were factors associated with poor outcome among reperfused patients. A logistic regression modeling revealed that only admission glucose value >140 mg/dL (odds ratio, 8.4; 95% CI, 1.76 to 40.02; P=0.005) emerged as an independent predictor of poor outcome despite tPA-induced recanalization. In patients with 6-hour persistent MCA occlusion, baseline NIHSS score >15 points (P=0.011) and proximal MCA occlusion (P=0.039) were variables associated with poor outcome on univariate analysis. In a logistic regression model, only NIHSS score >15 points (odds ratio, 11.9; 95% CI, 1.48 to 97.1; P=0.032) remained as an independent predictor of poor outcome and functional dependence at 3 months in nonreperfused tPA-treated patients. CONCLUSIONS: Hyperglycemia before reperfusion may in part counterbalance the beneficial effect of early restoration of blood flow, which translates into a worse outcome in hyperglycemic patients despite tPA-induced recanalization.

Adult↗

PubMed2003

[Stroke code impact on the efficacy of thrombolytic treatment].

BACKGROUND AND OBJECTIVES: Most stroke patients arrive to emergency rooms too late, many times beyond the therapeutic window for thrombolysis. The activation of a Stroke Code (SC)has proven to be effective in decreasing the latency time for starting therapy in clinical trials. However, its usefulness in routine clinical practice is uncertain. The aim of this study was to determine the feasibility of applying an SC in the daily clinical practice and to evaluate its impact on the efficacy of t-PA thrombolytic treatment. PATIENTS AND METHODS: We included middle-cerebral artery stroke patients treated with IV t-PA from June 2000 to December 2001 who were categorized into three periods of 6 months each. The influence of SC activation on the latency time, arterial recanalization and early neurological recovery was evaluated. RESULTS: Forty-eight patients were prospectively studied. A significant increase in the number of t-PA treated patients was observed in the three periods (4.8%, 5.3% and 8%). A significant progressive decrease (p = 0.036) in the overall delay to start t-PA was observed (from 161.4 to 130 minutes). The proportion of t-PA treated patients in whom SC was activated increased gradually (p = 0.032). SC activation reduced time from symptom onset to hospital arrival (p = 0.013) as well as the "door-to-needle"time (p = 0.049). The rate of early recanalization (p = 0.027) and neurological recovery (p = 0.036) at 48 hours was significantly higher in patients in whom SC was activated than in those in whom SC was not. CONCLUSIONS: SC activation is very useful in the management of acute stroke, increasing the rate of t-PA treated patients and improving the clinical outcome.

Adult↗