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PubMed1990

Selection of the order of autoregressive models for spectral analysis of Doppler ultrasound signals.

Autoregressive modelling includes a model identification procedure, that is, it is necessary to choose the order of the autoregressive (AR) process that best describes the given finite record (frame) of the signal. Four previously suggested procedures to choose the "best order" of AR processes have been tested: The "first zero crossing" of the autocorrelation function (FZC), the "final prediction error" (FPE), "Akaike's information criterion" (AIC), and the "criterion autoregressive transfer-function" (CAT). It was found that: (i) For more than 98% of the 1280 frames of Doppler signals analyzed the order selected by the various criteria was ten or less. (ii) For the same records of Doppler signals, FPE, AIC and CAT behave in a very similar manner, but the FZC criterion underestimates the order in relation to the others. (iii) For true AR processes, the order selected is frequently different from the true AR order when frames of 64 samples are used. When more samples are used FPE, AIC and CAT tend to select the correct order. (iv) The effect on the spectral estimate of using too high a model order is usually insignificant, while using too low an order can change the estimate more dramatically, that is, overestimating the model order is better than underestimating it.

Analysis of Variance↗
PubMed2005

Investigating population level trends in head injuries amongst child cyclists in the UK.

Case control studies suggest that cycle helmets offer their wearers protection from injury in the event of an accident. Nevertheless, encouragement and even compulsion of cycle helmet wearing has been controversial. This paper will re-examine another potential source of evidence for the role of cycle helmets. Administrative datasets are attractive because of their availability, but require careful analysis. The results presented here are obtained from analysing such data with an appropriate form of generalised additive model. Whilst helmet wearing surveys in the UK suggest strongly divergent trends in wearing rates between male and female children, there is little evidence from "Hospital Episode Statistics" to indicate similarly divergent trends in terms of head injury. Conversely, it can be confirmed that head injuries are falling faster among cyclists than pedestrians. Although case control studies suggest cycle helmets are not effective in reducing overall injuries, it is worth noting an increase in the proportion of male child cyclists reported by the police as being killed or seriously injured in road collisions. It might be tempting to use these results to suggest that helmets are not effective in reducing head injury at the population level. Whilst the careful analysis of population level data presented here is clearly important, this paper will discuss the reasons why population and individual level analyses of cycle helmets might be different and consider some of the difficulties in assigning cause and effect with imperfect observational data.

Accidents, Traffic↗
PubMed2005

San Francisco pedestrian injury surveillance: mapping, under-reporting, and injury severity in police and hospital records.

GOALS: Police reports of severely injured pedestrians help identify hazardous traffic areas in San Francisco, but they under-report non-fatal collisions. We set out to: identify injured pedestrians who were missing from police collision reports, see what biases exist in injury reporting and assess the utility of broad categories of police severe injury (including fatal) for mapping and analysis. METHODS: We linked data on injured pedestrians from police collision reports listed in the Statewide Integrated Traffic Reporting System (SWITRS, n = 1991) with records of pedestrians treated at San Francisco General Hospital (SFGH, n = 1323) for 2000 and 2001. Data were analyzed using bivariate statistics, logistic regression and mapping. RESULTS: : We found that police collision reports underestimated the number of injured pedestrians by 21% (531/2442). Pedestrians treated at SFGH who were African-American were less likely then whites (odds ratio = 0.55, p-value < or= 0.01), and females were more likely than males (odds ratio = 1.5, p-value < or = 0.01) to have a police collision report. Over 70% of pedestrians deemed by the police to have a severe injury received treatment at SFGH, regardless of the collision's distance from SFGH. The sensitivity of a police-designated severe injury (including fatal) was 69% and the specificity was 89% when compared with a known SFGH assessment. But, sensitivity declined when we included pedestrians without a SFGH record. CONCLUSION: Though collision reports have demonstrated limitations, broad categories of police severity may be sensitive enough to map locations where numerous severe injuries occur, for timely countermeasure selection.

Accidents, Traffic↗
PubMed2005

Clinical characteristics and surgical outcomes of pediatric rhegmatogenous retinal detachment in Taiwan.

PURPOSE: To evaluate the clinical features and surgical and visual outcomes of rhegmatogenous retinal detachment (RRD) in the pediatric population. DESIGN: Retrospective, noncomparative, interventional case series. METHODS: A review of patients under 18 years who underwent primary retinal detachment surgery at National Taiwan University Hospital from 1989 to 2003 was conducted. RESULTS: Included in the study were 152 eyes of 146 patients (mean age of 13.1 years). Male patients comprised 69.9% of the sample. Bilateral RRD was present in 4.1%. Etiologies included myopia >4 diopters (37.5%), trauma (32.9%), developmental anomaly (11.8%), previous surgery (5.9%), previous uveitis (3.9%), atopic dermatitis (2.6%), and unknown (5.3%). Macular detachment was found in 73.0%. The most common primary treatment was scleral buckling (61.2%). Single-operation reattachment was accomplished in 58.5% of patients and eventual reattachment in 78.3% of patients occurring in a mean of 1.5 (SD = 0.9) operations. Average postoperative follow-up time was 48.3 months. Visual improvement occurred in 42.8%, remained the same in 32.2%, and worsened in 19.1%. In the logistic regression model, statistically significant risk factors for poor surgical outcome were nonmyopic RRD (P = .026), macular involvement (P = .01), and presence of proliferative vitreoretinopathy (P = .07). CONCLUSIONS: Myopia >4 diopters was the most common etiology in retinal detachment in our sample, followed by trauma. Myopia (> -4.0 diopters) may be more common than previously reported. Most eyes (78.3%) were anatomically reattached after multiple surgeries. Retinal detachment not associated with myopia is a newly identified predictor for poor surgical outcomes.

Adolescent↗
PubMed2005

Atom-based 3D-chiral quadratic indices. Part 2: prediction of the corticosteroid-binding globulinbinding affinity of the 31 benchmark steroids data set.

A quantitative structure-activity relationship (QSAR) study to predict the relative affinities of the steroid 'benchmark' data set to the corticosteroid-binding globulin (CBG) is described. It is shown that the 3D-chiral quadratic indices closely correlate with the measured CBG affinity values for the 31 steroids. The calculated descriptors were correlated with biological data through multiple linear regressions. Two statistically significant models were obtained when non-stochastic (R = 0.924 and s = 0.46) as well as stochastic (R = 0.929 and s = 0.46) 3D-chiral quadratic indices were used. A leave-one-out (LOO) approach to model validation is used here; the best results obtained in the cross-validation procedure with non-stochastic (q2 = 0.781) and stochastic (q2 = 0.735) 3D-chiral quadratic indices are better or similar to most of the 3D-QSAR approaches reported so far. These results support the idea that the 3D-chiral quadratic indices may be helpful in prediction of the corticosteroid-binding affinity for new compounds.

Computational Biology↗
PubMed2005

QSAR analysis of meclofenamic acid analogues as selective COX-2 inhibitors.

The use of quantitative structure-activity relationships, since its advent, has become increasingly helpful in understanding many aspects of biochemical interactions in drug research. This approach was utilized to explain the relationship of structure with biological activity of selective COX-2 inhibitors. The enormity of the COX-2 discovery is reflected in the unprecedented speed at which research laboratories have sought to validate its clinical implications. Presented herein is a series of 21 derivatives of meclofenamic acid with selective COX-2 inhibitory activity. Several statistically significant regression expressions were obtained for both COX-1 and COX-2 inhibition using sequential multiple linear regression analysis method. Two of these models were selected and validated further, which revealed the importance of Kier molecular flexibility index for COX-2 inhibitory activity and the number of hydrogen bond donor atoms for COX-1 inhibitory activity. Additionally, linear correlation of molecular flexibility with COX-1 and COX-2 inhibitory activities revealed that flexibility of molecules at COX-2 active site can improve the selectivity of COX-2 inhibitors.

Cyclooxygenase 2↗
PubMed2006

An adaptive signal compression system with pre-specified reconstruction quality and compression rate.

Two essential properties of a signal compression method are the compression rate and the distance between the original signal and the reconstruction from the compressed signal. These two properties are used to assess the performance and quality of the method. In a recent work [B. Tümer, B. Demiröz, Lecture Notes in Computer Science-Computer and Information Sciences, volume 2869, chapter Signal Compression Using Growing Cell Structures: A Transformational Approach, Springer Verlag, 2003, pp. 952-959], an adaptive signal compression system (ACS) is presented which defines the performance of the system as a function of the system complexity, system sensitivity and data size. For a compression method, it is desirable to formulate the performance of the system as a function of the system complexity and sensitivity to optimize the performance of the system. It would be further desirable to express the reconstruction quality in terms of the same system parameters so as to know up front what compression rate to end up with for a specific reconstruction quality. In this work, we modify ACS such that the modified ACS (MACS) estimates the reconstruction quality for a given system complexity and sensitivity. Once this relation is identified it is possible to optimize either compression rate or reconstruction quality with respect to system sensitivity and system complexity while limiting the other one.

Algorithms↗
PubMed2006

Comparison of fast Fourier transformation and autoregressive modelling as a diagnostic tool in analysis of lower extremity venous signals.

In this study, we have compared the efficacy of autoregressive modelling (ARM) and fast Fourier transformation (FFT) of Doppler signals from lower extremity veins of healthy volunteers in various physiologic situations. Compared to FFT, ARM produced smooth spectra and less spectral broadening both in sonograms and power spectra. However, faulty positioning of the peaks along the time axis in FFT-derived power spectral density curves show that FFT is not a suitable method if these graphs are to be used as a diagnostic tool. Analysis of ARM-based venous sonograms and power spectral density graphs revealed that FFT should not be used in signals with high power spectral density levels and low-frequency bandwidth within limited segments of time.

Adult↗
PubMed2006

Impact of volume guarantee ventilation on arterial carbon dioxide tension in newborn infants: a randomised controlled trial.

OBJECTIVE: To compare the effects of the two modes of ventilation, synchronous intermittent positive pressure ventilation (SIPPV) and SIPPV with Volume Guarantee (VG), on arterial carbon dioxide tension (PaCO(2)) immediately after neonatal unit admission. STUDY DESIGN: Randomised study of ventilation mode for premature inborn infants admitted to two tertiary neonatal units. After admission, infants were randomised to receive either SIPPV or VG using a Dräger Babylog 8000 plus ventilator. In the SIPPV group, peak airway pressure was set clinically. In the VG group, desired tidal volume was set at 4 ml/kg, with the ventilator adjusting peak inspiratory pressure to deliver this volume. The study was completed once the first arterial PaCO(2) was available, with the desirable range defined as 5-7 kPa. RESULTS: PaCO(2) was significantly higher in the VG group (VG: 5.7 kPa, SIPPV: 4.9 kPa; p=0.03). The VG group had fewer out-of-range PaCO(2) values (VG: 42%, SIPPV: 57%) and fewer instances of hypocarbia <5 kPa (VG: 32%, SIPPV: 57%) but neither difference achieved statistical significance. Regression analysis showed PaCO(2) was negatively correlated with gestation (r=-0.41, p=0.01) and also with the mode of ventilation (r=0.32, p<0.05). In the VG group, all infants 23-25 weeks' gestation had out-of-range PaCO(2) values. VG significantly reduced the incidence of out-of-range PaCO(2) and hypocarbia in infants over 25 weeks' gestation (VG: 27%, SIPPV: 61%; p<0.05). CONCLUSION: Using this strategy, VG appears feasible in the initial stabilisation of infants over 25 weeks' gestation, with a halving of the incidence of hypocarbia. In the small number of babies studied below this gestation, VG was not found to be effective.

Arteries↗
PubMed2004

Clinical ethical dilemmas for vascular surgeons (the VASCUETHICS study): are self-interest attitudes related to professional seniority?

OBJECTIVE: To evaluate the association between professional seniority and self-interest (PSI) attitudes in the resolution of vascular ethical dilemmas (VED). DESIGN: Cross-sectional. SUBJECTS: Vascular surgeons (residents included) from the 28 vascular teaching departments of Spain. Measurements. Multidisciplinary team-designed questionnaire of 5 VED. Each VED had 3 different answers (attitudes): 2 favouring legitimate ethical attitudes (LEA) and 1 favouring PSI. The questionnaire was self-administered and all participants stated their degree of agreement with each answer on a continuous Likert scale. PSI was evaluated by: (1) adding the magnitudes of the 5 answers favouring PSI (absPSI); and (2) by comparing in each case the magnitude of the PSI answer with that of the 2 LEA (relPSI). STATISTICS: Linear regression adjusted by confounding factors. RESULTS: Two hundred and fifty-three vascular surgeons from the 26 participating teaching vascular departments of public hospitals completed the questionnaire (87.5% surgeons/department). Surgeon characteristics were: (1) median age 37 years; (2) 187 (74%) male; (3) 59 (23%) brought up with a health professional relative; (4) 94 (38%) had additional private practice; (5) 133 (65%) professed religious beliefs; and (6) 1-10 years of experience in 116 (47%), 11-20 years in 58 (24%), 21-30 years in 57 (23%), and >30 years in 15 (6%). The multivariate analysis disclosed that for every 10-years rise in professional seniority there was a 3.2% increase in absPSI (p=0.007, adjusted by variables 3 and 4), and a 3.4% increase in relPSI (p=0.002, adjusted by variable 5). CONCLUSIONS: Professional seniority is associated with a slight increase in pro-PSI attitudes in cases of vascular ethical dilemma. Both vascular surgeons and health institutions should promote the reversal of this worrying tendency.

Adult↗
PubMed2004

Use of outcomes-based data in reducing high-order multiple pregnancies: the role of age, diagnosis, and embryo score.

OBJECTIVE: To identify high-risk categories for high-order multiple pregnancy (HMP) in in vitro fertilization (IVF), establish clinic-specific HMP risk data for counseling use, and verify their utility in reducing HMP. DESIGN: Before and after intervention study. SETTING: Two IVF programs using the same embryology laboratory and IVF protocols. PATIENT(S): All IVF patients undergoing fresh embryo transfers. INTERVENTION(S): Use of clinic-specific age, diagnosis, and embryo score (ES) risk data in assessing individual HMP risk during informed consent. MAIN OUTCOME MEASURE(S): HMP and pregnancy outcomes. RESULT(S): In determining clinic-specific high risk categories and developing outcomes-based HMP risk data for counseling, the good outcome rate (GR) was defined as the percentage of singleton or twin deliveries per cycle and the bad outcome rate included no pregnancy or nondelivered pregnancies (miscarriages, multifetal reduction) and HMP per cycle. During 1995 to 1999, age <35 years, calculated morphologic ES, and donor egg (DE) cycles were factors shown by logistic regression to statistically significantly affect the GR. The optimal GRs for DE <35 and >or=35 years (donor age), and non-DE cycles <35 years were achieved with two (57.7%), three (43.2%), and three (43.2%) embryos transferred, respectively. A DE <35 years with >or=3 embryos transferred had the highest risk for HMP. The GR correlated (0.91) with the ES according to the formula: GR = 3.3 + 2.0 ES, when ES range was between 4 and 26. Clinic-specific risks for HMP based on age, diagnosis, and ES were developed and considered while counseling for ET during 2004. The clinic-specific HMP risk data made for a reduction in the HMP rate of 90.9% for DE-IVF (11.8% to 1%) and 53.8% for all IVF (9.1% to 4.2%), without decreases in clinical pregnancy or delivery rates. Physicians showing the greatest decline (64%) in HMP had no reduction in pregnancy or delivery rates. CONCLUSION(S): The use of clinic-specific HMP risk data in counseling based on age, diagnosis, and ES provided a 53% to 64% reduction in HMP without affecting rates of pregnancy or delivery. The clinic-specific ES system correlated closely with good outcomes. A standardized ES system may provide useful information for counseling during ET informed consent.

Adult↗
PubMed2006

[Are there any factors predicting failure or complications rates of trans-obturator surgery for stress urinary incontinence?].

OBJECTIVE: Since 2001 and the publication by Delorme of the trans-obturator route in the stress urinary incontinence (SUI), this technique has known an increasing development in France. The aim of this study is to evaluate the impact of different predicting factors on results and complications of trans-obturator surgery. PATIENTS AND METHODS: It is a retrospective, multicentric study, including 4 centers, 14 surgeons and 196 patients operated between February 2003 and August 2005. We have realized a univariate (Chi2 test) and multivariate (logistic regression test) statistic analysis concerning 7 sub-groups defined according to the literature on the TVT. RESULTS: Age>55 years (P=0,044) and SUI grade>2 (P=0,028) are statistically associated with a decrease of surgical success, age>55 years is also associated with an increase of complications rate in univariate (P=0,033) and multivariate (P=0,048) analysis. DISCUSSION AND CONCLUSION: Age>55 years should be considered, according to us, as a risk factor of surgical failure and complications in the trans-obturator surgery for SUI, none of the others risk factors found in the literature on the TVT seems to have an influence, in this study, on the results of trans-obturator surgery for SUI.

Adult↗
PubMed2005

Development of three layered buccal compact containing metoprolol tartrate by statistical optimization technique.

The objective of this work to evaluate the effect of formulation variables on release properties and bioadhesive strength in development of three layered buccal compact containing highly water-soluble drug metoprolol tartrate (MT) by statistical optimization technique. Formulations were prepared based on rotatable central composite design with peripheral polymer ratio (carbopol 934P: HPMC 4KM) and core polymer ratio (HPMC 4KM: sodium alginate) as two independent formulation variables. The three layered buccal compact comprises a peripheral layer, core layer and backing layer. Four dependent (response) variables were considered: bioadhesion force, percentage MT release at 8 h, T50% (time taken to release 50% of drug) and release exponent (n). The release profile data was subjected to curve fitting analysis for describing the release mechanism of MT from three layered buccal compact. The main effects and interaction terms was quantitatively evaluated by quadratic model. The decrease in MT release was observed with an increase in both the formulation variables and as the carbopol: HPMC ratio increases the bioadhesive strength also increases. The desirability function was used to optimize the response variables, each having a different target and the observed responses were highly agreed with experimental values. The results demonstrate the feasibility of the model in the development of three layered buccal compact containing highly water-soluble drug MT.

Administration, Buccal↗
PubMed2005

Osteoporosis prevention education: behavior theories and calcium intake.

Osteoporosis is a worldwide health concern. Preventing osteoporosis, and subsequent fractures, has become a goal of many health care practitioners, especially dietetics professionals. However, few prevention models have proven effective. The goal of this project was to determine whether an educational, theory-based osteoporosis prevention program would significantly impact calcium intake. This project used a convenience sample of 42 women who participated in an 8-week educational intervention, similarly to a community class. The program included hands-on activities to increase self-efficacy and was based on the Health Belief Model and Theory of Reasoned Action (TRA). The main outcome measures were calcium intake and constructs from the Health Belief Model and TRA. Significant changes in the Health Belief Model and TRA constructs at postintervention included increased perceived susceptibility to osteoporosis ( P <.001), perceived benefits to increasing calcium intake ( P <.001), and increased self-efficacy related to calcium intake ( P </=.003). Statistically significant regression equations were found for all preintervention intentions related to calcium. Postintervention calcium intake significantly increased to 821+/-372 mg/day ( P <.0001). Results of this project can be used as guidelines for dietetics professionals to develop osteoporosis prevention programs for their clientele.

Adult↗
PubMed2006

Salad and raw vegetable consumption and nutritional status in the adult US population: results from the Third National Health and Nutrition Examination Survey.

OBJECTIVE: To examine the relationship between reported salad consumption and serum nutrient levels as well as dietary adequacy, as defined by nutrient intakes, in relation to the National Academy of Science Food and Nutrition Board Guidelines, in pre- and postmenopausal women and in men of comparable ages. DESIGN: Analyses of 24-hour recalls were conducted to determine dietary intake using the Third National Health and Nutrition Examination Survey data. Salad consumption was assessed based on intakes of salad, raw vegetables, and salad dressing. SUBJECTS: Nine thousand four hundred-six women and 8,282 men aged 18 to 45 years and older than 55 years were examined between 1988 and 1994. STATISTICAL ANALYSES: Regressions were used to model associations between salad and raw vegetable consumption and selected serum nutrient outcomes. Usual nutrient intake distributions were estimated using the Iowa State University method for adjustment of the distribution. The Estimated Average Requirement method was used to determine the proportion of subjects with inadequate intake for each nutrient. RESULTS: The consumption of salads, raw vegetables, and salad dressing was positively associated with above-median serum micronutrient levels of folic acid, vitamins C and E, lycopene, and alpha- and beta-carotene. Each serving of salad consumed was associated with a 165% higher likelihood to meet the recommended Dietary Allowance for vitamin C in women and 119% greater likelihood in men. CONCLUSIONS: Salad consumers tended to have more favorable intakes of vitamins C and E, folic acid, and carotenoids, after adjustment for other differences. The significant and consistently higher serum values of these vitamins among salad consumers suggest that they are being well absorbed from salad. Salad, salad dressing, and raw vegetable consumption can be an effective strategy for enhancing nutritional adequacy and increasing vegetable consumption in the population at large.

Adolescent↗
PubMed2005

Effect of inspiratory time on tidal volume delivery in anesthesia and intensive care unit ventilators operating in pressure control mode.

STUDY OBJECTIVE: To compare the effect of inspiratory time and lung compliance on tidal volume (Vt) delivery in anesthesia and intensive care unit (ICU) ventilators operating in pressure control mode. SETTING: Respiratory research laboratory of a tertiary care medical center. DESIGN: Two anesthesia ventilators with pressure control capability (Narkomed 6000, Drager Medical, Inc, Telford, Pa, and the Datex-Ohmeda Aestiva 5, Datex-Ohmeda, Inc, Madison, Wis) and one critical care ventilator (Puritan Bennett 7200, Puritan-Bennett, Pleasanton, Calif) were studied under varying inspiratory time and lung compliance conditions using a mechanical lung model. INTERVENTION: Each ventilator was set to pressure control mode at a fixed inspiratory/expiratory (I/E) ratio. The respiratory rate (RR) was varied between 6 and 28 breaths per minute. Lung compliance and inspiratory time settings were set to simulate clinical conditions known to affect anesthesia ventilator performance. MEASUREMENTS: Inspiratory flow, Vts, and peak airway pressures were measured using the on-board monitor for each ventilator, and confirmed with the Bicore CP-100 pulmonary mechanics monitor (Bicore Monitoring Systems, Inc, Irvine, Calif). To assess differences in inspiratory flow between ventilators, airway pressures were continuously monitored during inspiration. MAIN RESULTS: Increasing RRs caused delivered Vts to decrease for all ventilators. However, decreases in Vts were significantly larger for anesthesia than for ICU ventilators. At a lung compliance of 0.02 L/cm H(2)O and set Vt of 700 mL, Vt delivery for the Puritan Bennett 7200 ventilator remained at 88% of baseline, but decreased to 76% for the Aestiva 5 when RRs were increased from 6 to 28 breaths per minute (P < .0025). Airway pressure tracings demonstrated a slower increase in inspiratory airway pressure for the Aestiva 5 than for the other ventilators. CONCLUSION: Differences in inspiratory flow delivery between ICU and anesthesia ventilators can cause differences in Vt delivery when the pressure control mode is used at high RRs. These differences can significantly impact the perioperative care of critically ill patients requiring ventilatory support.

Air Pressure↗
PubMed2004

Craniomaxillofacial trauma in children: a review of 3,385 cases with 6,060 injuries in 10 years.

PURPOSE: Trauma is the leading cause of diseases and death in children. The goal of this study was to assess the impact of the main causes of accidents among children resulting in pediatric craniomaxillofacial trauma. PATIENTS AND METHODS: Between 1991 and 2000, data for 3,385 patients younger than 15 years of age who sustained a total of 6,060 craniomaxillofacial injuries were recorded for cause of injury, age and gender distribution, frequency and type of injury, injury mechanisms, localization and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures, and concomitant injuries. Univariate statistical analyses were followed by logistic regression analyses for the 3 injury types to determine the impact of the main injury causes on the type of injury at different ages in pediatric facial trauma patients. RESULTS: Play (58.2%), sport (31.8%), and traffic accidents (5%), acts of violence (3.9%), and other causes (1.1%) were noted. A total of 389 patients (11.5%) had 615 fractures, 2,582 patients (76.3%) had 3,384 dentoalveolar injuries, and 1,697 patients (50.1%) had 2,061 soft tissue injuries. The girl-to-boy ratio was 3:5, and the mean age was 7 +/- 4.4 years. For children sustaining facial trauma, logistic regression analyses revealed increased risks for fractures (+238%) and soft tissue lesions (+89%) in children involved in traffic accidents. Dental trauma was more frequent (>+38%) in both sport and play accidents (all P <.001). CONCLUSIONS: This study dissected the distinct impact of injury mechanisms in pediatric craniomaxillofacial trauma. Logistic regression analyses revealed statistically highly significant outcome differences in pediatric facial trauma depending on the injury mechanism.

Accidental Falls↗
PubMed2004

Infrainguinal vein bypass graft revision: factors affecting long-term outcome.

OBJECTIVES: We sought to determine the long-term results of revision procedures performed for repair of stenotic lesions in infrainguinal vein bypass grafts. METHODS: A retrospective review of 188 vein grafts, from a total series of 1260 bypasses, undergoing revision of stenotic lesions between January 1, 1987, and December 31, 2002, at Brigham & Women's Hospital was undertaken. Lesions were identified by recurrence of symptoms, change in examination findings, or with routine duplex ultrasound graft surveillance. Demographic and medical risk factors, and surgical variables were analyzed with respect to patency outcomes after the initial graft revision, with descriptive statistics, logistic regression, and life table analysis. Primary and secondary patency rates were determined from the time of graft revision. RESULTS: Patients included 108 men (57%) and 80 women (42%) who underwent revision at a mean age of 67.8 years. One hundred thirty grafts required only a single revision, whereas 58 required subsequent additional revisions. Revision procedures included 99 vein patches (52.7%), 23 jump grafts (12.2%), 23 interposition grafts (12.2%), 8 transpositions to new outflow vessels (4.3%), and 35 balloon angioplasty procedures (18.6%). During a mean follow-up of 1535 days, 5-year primary patency rate was 49.3% +/- 4.5% (SE) and 5-year secondary patency rate was 80.3% +/- 3.6%. There was no difference in patency rate for different revision procedures, type of vein graft, indication for the original procedure, or for patients with diabetes mellitus or renal disease. The overall limb salvage rate was 83.2% +/- 3.5% 5 years after graft revision. With COX proportional hazard analysis of time to failure of the revision procedure, the outflow level of the original bypass and the time of revision proved to be an important predictor of durability of the graft revision. Revision of popliteal bypass grafts resulted in a 60% 5-year primary patency rate, whereas revision of tibial grafts resulted in a 42% 5-year primary patency rate (P = .004; hazard ratio [HR], 2.06). Five-year secondary patency rates were 90% and 76%, respectively (P = .009; HR = 3.43). The timing of the graft revision proved an additional predictor. Grafts revised within 6 months of the index operation had lower primary patency than those with later revisions (42.9% vs 80.7%, respectively; HR = 1.754; P = .0152). CONCLUSIONS: Vein graft revisions offer durable patency and limb salvage rates after repair of stenotic infrainguinal bypass grafts. Vigilant ongoing surveillance is essential, because 30.9% of revised grafts will develop additional lesions that will require repair. Tibial level bypass grafts that require early repeat intervention to treat graft stenosis are at particular risk for development of subsequent lesions.

Aged↗