In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
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Question: Context: Therapeutic and prophylactic vena cava filters (VCFs) are used to prevent pulmonary embolism. Concerns exist over placing a permanent filter in a young trauma patient. Recently, retrievable VCFs have become available. One such filter is the OptEase, which has a recommended time of removal of up to 23 days after insertion. Data supporting this recommendation are sparse. Many trauma patients will need filters for more than 2 weeks, and there are no data evaluating the safety of removal after extended time periods. The purpose of this study was to determine the safety, feasibility, and reaction of the vena cava when removing the OptEase retrievable VCF at different time intervals.', 'Twenty Yorkshire cross pigs (80-113 kg) underwent general anesthesia with tiletamine and zolazepam. Filters were placed in the infrarenal vena cava (VC) through the femoral vein under fluoroscopic guidance. Animals were then divided into four groups. In group 1, filters were removed at 14 days; in group 2, at 30 days; in group 3, at 60 days; and in group 4, at 90 days. Removal was attempted using a snare-and-sheath technique through the femoral vein. Animals with successful filter removal were allowed to recover; then, the animals underwent autopsy (gross and microscopic VC examination) 2 months later. Animals with unsuccessful filter removal underwent autopsy immediately after attempted removal. Venacavograms were taken at filter insertion, at removal, and before autopsy to evaluate any VC abnormalities.', 'Successful removal of the filter in all five pigs (100%) was reliably performed only in the 14-day group. In this group, the initial VC transverse diameter was 19.4 +/- 0.8 mm and was significantly reduced to 9.8 +/- 1.1 mm (p < 0.05) immediately after removal. Sixty days later, before autopsy, VC diameter had increased to 15.3 +/- 1.9 mm, which was significantly larger than at removal (p < 0.05) but not different from the initial value. In the 30-day group, removal was successful in only one of five animals. Although removal was successful in the one pig, autopsy at 2 months postremoval revealed total occlusion of the VC. Filters could not be removed from 60- and 90-day groups. At autopsy, the VCF struts were embedded or protruded through the VC wall. Microscopic examination of the VC revealed significant scarring underneath and between the struts.\Question: Is removal of the OptEase retrievable vena cava filter feasible after extended time periods because of filter protrusion through the vena cava?

Answer: Removal of the retrievable OptEase VCF may be successfully performed up to 14 days after insertion. Strut protrusion through the VC wall prohibited successful and safe removal at extended time intervals.

Question: Context: Cognitive changes after ischemic stroke are often overlooked, particularly acutely and in patients with mild or transient deficits. We assessed patients with transient ischemic attack (TIA)/minor stroke with serial cognitive screening tests. We tested the hypothesis that mild acute deficits are transient and improve after TIA/minor stroke.', 'Patients with acute TIA/minor ischemic stroke, without a history of cognitive impairment, presenting with a National Institute of Health Stroke Scale score 3 were assessed <72 hours of onset. Patients were administered the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) at days 1, 7, 30, and 90. Cognitive impairment was defined as MoCA <26 and MMSE 26.', 'One hundred patients with a median (interquartile range) National Institute of Health Stroke Scale score of 1 (2) and median age of 68 (20) years were included. Baseline median MoCA score (26 [4]) was lower than the MMSE (29 [2]; P<0.0001). Cognitive impairment was detected in 54 of 100 patients (54%) with MoCA and 16 of 100 (16%; P=0.001) with MMSE. MoCA scores improved at day 7 (27 [5]), day 30 (28 [2]), and day 90 (28 [2]; P<0.0001). Resolution of cognitive deficits was because of resolution of recall deficits.\Question: Do serial montreal cognitive assessments demonstrate reversible cognitive impairment in patients with acute transient ischemic attack and minor stroke?

Answer: Acute temporary cognitive impairment after TIA/minor stroke is common. The MoCA is sensitive to these changes, but the MMSE is not. Routine cognitive assessment after TIA/minor stroke may be warranted and relevant to return to activities even when other neurological deficits are not evident.

Question: Context: Retrospective cohort study.', 'To compare short-term morbidity for primary and revision posterior lumbar fusions.', 'Revision lumbar fusions are unfortunately relatively common. Previous studies have described an increased risk of postoperative complications after revision lumbar fusion; however, these studies have been limited by small sample sizes, poor data quality, and/or narrow outcome measures. There is a need to validate these findings using a high-quality, national cohort of patients to have an accurate assessment of the relative risk of revision posterior lumbar fusions compared with primary lumbar fusion.', 'The prospectively-collected American College of Surgeons National Surgical Quality Improvement Program database was used to identify patients that underwent undergoing primary and revision posterior lumbar fusion from 2005 to 2013. The occurrence of individual and aggregated postoperative complications within 30 days, along with rates of blood transfusion and readmission, were compared between primary and revision procedures using bivariate and multivariate Poisson regression with robust error variance to control for patient and operative characteristics. Operative time and postoperative length of stay were compared between groups using bivariate and multivariate linear regression.', 'Of the 14,873 posterior lumbar fusion procedures that met inclusion criteria, 1287 (8.7%) were revision cases. There were no differences in the rates of 30-day postoperative complications or readmission between primary and revision posterior lumbar fusion using multivariate analysis to control for patient and operative characteristics. Similarly, no significant differences were found for operative time or postoperative length of stay. There was an increased rate of blood transfusion for revision surgery compared with primary surgery (relative risk 1.4, P<0.001).\Question: Do primary and Revision Posterior Lumbar Fusion Have Similar Short-Term Complication Rates?

Answer:
This study suggests that revision posterior lumbar fusion does not carry significantly increased risk of complications or readmission compared with a primary posterior lumbar fusion. Patients undergoing revision surgery were more likely to receive a blood transfusion. This information suggests that general health risk stratification for revision procedures can be similar to that considered for primary cases.