General anesthesia soon after dialysis may increase postoperative hypotension - A pilot study.

IntroductionPilot study associating hemodialysis-to-general-anesthesia time interval and post-operative complications in hemodialysis patients to better define a more optimal pre-anesthetic waiting period.MethodsPre-anesthetic and 48-hours post-anesthetic parameters (age, gender, body-mass-index, pre-operative ultrafiltrate, potassium, renal disease etiology, hemodialysis sessions per week, Acute Physiology and Chronic Health Evaluation-II score, Portsmouth-Physiologic and Operative Severity Score for the Enumeration of Mortality and Morbidity, American Society of Anesthesiologists physical status, Johns Hopkins Surgical Classification System Category, surgical urgency, intra-operative fluids, estimated blood loss, post-operative complications) were collected on chronic hemodialysis patients between 11/2009-12/2010. Continuous data were analyzed by Analysis of Variance or t-test. Bivariate data were analyzed by Fisher's Exact Test. Relative Risks/Confidence Intervals were calculated for statistically significant comparisons (p=0.05). Exclusion criteria were incomplete records, peritoneal dialysis, intra-operative hemodialysis, liver transplant, and cardiopulmonary bypass.ResultsPatients were grouped by dialysis to anesthesia time interval: Group 1 >24 hours, Group 2 7-23.9 hours, Group 3 < 7 hours. Among Surgical Category 3-5 patients, hypotension was more common in Group 3 than Group 1 (63.6% vs 9.2%, p<0.0001, relative risk=6.9, confidence interval=3.0-15.7) or Group 2 (63.6% vs 17.3%, p=0.0002, relative risk=3.7, confidence interval=1.9-7.2). Other complications rates were not statistically significant. Disease and surgical severity scores, preoperative ultrafiltrate, and intra-operative fluids were not different.ConclusionsPost-anesthetic hypotension within 48 hours was more common in those with < 7 hours interval between dialysis and anesthesia. Therefore, if surgical urgency permits, a delay of ≥7 hours may limit postoperative hypotension. More precise associations should be obtained through a prospective study

Carryless Arithmetic Mod 10

We investigate what arithmetic would look like if carry digits into other digit position were ignored, so that 9 + 4 = 3, 5 + 5 = 0, 9 X 4 = 6, 5 X 4 = 0, and so on. For example, the primes are now 21, 23, 25, 27, 29, 41, 43, 45, 47, ... .Comment: 7 pages. To the memory of Martin Gardner (October 21, 1914 -- May 22, 2010). Revised version (with a number of small improvements), July 7 201

On Asymmetric Coverings and Covering Numbers

An asymmetric covering D(n,R) is a collection of special subsets S of an n-set such that every subset T of the n-set is contained in at least one special S with |S| - |T| <= R. In this paper we compute the smallest size of any D(n,1) for n <= 8. We also investigate ``continuous'' and ``banded'' versions of the problem. The latter involves the classical covering numbers C(n,k,k-1), and we determine the following new values: C(10,5,4) = 51, C(11,7,6,) =84, C(12,8,7) = 126, C(13,9,8)= 185 and C(14,10,9) = 259. We also find the number of nonisomorphic minimal covering designs in several cases.Comment: 11 page

Instructional Implications of the Michigan Educational Assessment Program as an Accountability Instrument

Problem. In Michigan, early elementary school teachers are held accountable for instructional decisions they made based on the number of children who pass the state standardized reading test, the Michigan Educational Assessment Program (MEAP). Although state officials claim the MEAP can inform instruction, no data are regularly collected to describe reading instructional practices or the relationship between current practices and the percentage of students who pass the MEAP. Method. Using a survey instrument, this study measured the amount of instructional time Kindergarten through Grade 4 teachers reported that they devoted to the development of 19 different components or activities within their classroom reading and language arts program. The Pearson product-moment correlation was applied to determine therelationship between the amount of reported time devoted to each of these activities and the percentage of students who achieved a satisfactory level on the Grade 4 MEAD test in the participating teachers\u27 schools. Results. Descriptive analysis showed grade-specific preferences in the amount of time teachers report devoting to various activities within their language arts programs. Despite balanced approaches being reported across all grade levels, only eight significant relationships were found between teacher practices and the MEAP. Of the eight, four were found between Grade 4, two for Grade 3, one for Grades 2 and 1, and none for Kindergarten. Conclusions. Although the reading activities and components measured were representative of actual practice in this Southwestern Michigan county, the fact that, at the most, only four variables for any one grade level could be identified that showed a significant relationship between grade level practices and the MEAP calls to question whether the state standardized test can be used to inform instruction. If the MEAP cannot be connected to actual classroom instructional practices, then holding teachers accountable for their instructional decision making by the MEAP is a questionable practice that lacks methodological consistency and dismisses the necessary link between a behavior and its consequence