Biomedical subjects

C Calderón

Publications and source records attributed to C Calderón.

46 records · Page 3Linked to original sources

PubMedDate not supplied

Effect of delayed centrifugation or reading on the detection of ABO incompatibility by the immediate-spin crossmatch.

The immediate-spin (IS) crossmatch is a method that detects ABO incompatibility. However, under certain circumstances, this test may show unwanted negative or weak results, even though the red cells (RBCs) and serum being tested are ABO incompatible with each other. The present study investigated the potential effect of delayed centrifugation or reading on the IS crossmatch test performance. When the centrifugation step of the IS crossmatch between group O sera and group A1 RBCs was delayed for 2 minutes, 5 of 200 crossmatches showed no agglutination with only trace (n = 2) or moderate (n = 3) hemolysis, and one crossmatch showed only weak, macroscopic agglutination, but moderate hemolysis. All six sera contained A antibodies that were lytic in vitro and, therefore, probably were capable of causing in vivo hemolysis of transfused A1 RBCs. Delaying the reading of the IS crossmatch test for 2 minutes had no apparent effect on test performance. These data demonstrate the importance of technologists' recognition of hemolysis as a positive result on IS crossmatches, especially if the performance of the centrifugation step of the test is delayed. Furthermore, the unwanted negative agglutination results were abolished by suspending the group A1 RBCs in saline containing EDTA. The authors' laboratory has modified its IS crossmatch procedure so that donor RBCs are routinely suspended in saline containing EDTA before testing. This procedural change should increase the safety of the IS crossmatch.

ABO Blood-Group System↗

PubMedDate not supplied

Semiquantitative culture of subcutaneous segment for conservative diagnosis of intravascular catheter-related infection.

BACKGROUND: Sensitivity and negative predictive values of combined surface cultures (skin and hub) are high in the presumptive diagnosis of catheter-related infection, but specificity and PPVs are poor. The purpose of the study was to evaluate the yield of the semiquantitative culture of the subcutaneous segment in the diagnosis of colonization of the catheter tip without removal of the catheter. METHODS: A prospective study was performed in 124 nontunneled central venous catheters that were removed because of suspected infection or the end of therapy. Catheter colonization was considered if >15 colony-forming units (CFU) in the roll procedure or > 1,000 CFU in the quantitative Cleri procedure were recovered from the tip cultures ("gold standard"). Before removing the catheter, a semiquantitative culture of skin surrounding the point of insertion, a semiquantitative culture of the subcutaneous segment (after removing the catheter only 2 cm), a semiquantitative cultures of the hub, and a pareated quantitative blood culture were performed. Receiver operating characteristic curves were calculated to estimate the cutoff points, and a culture was considered positive when CFUs were > or =15, > or =15, and > or =5 for skin, hub, and subcutaneous segment cultures, respectively. RESULTS: Catheter colonization was detected in 51 catheters. The mean duration of catheterization was 14 +/- 8 days, and the rates of incidence of tip colonization and bacteremia were 2.9 per 100 catheter days and 1.2 per 100 catheter days, respectively. Sensitivity of skin, subcutaneous, and hub cultures analyzed individually were < or =61%; however, specificity and positive predictive values (PPVs) of subcutaneous segment cultures were significantly higher than skin cultures (94% and 88.5% vs 71.6% (p = .001) and 62% (p = .014), respectively). Sensitivity of the combined skin and hub cultures and of the combined subcutaneous segment and hub cultures were similar: 86.2% and 84.3%, respectively; however, specificity and PPVs of this latter combination were significantly higher than former: 82% and 78.1% vs 59.7% (p = .008) and 61.9% (p = .07), respectively. The likelihood ratio of a positive test for the combined subcutaneous segment and hub culture was 4.68, and only 2.13 for the combined skin and hub culture. CONCLUSIONS: These results indicate that the combined subcutaneous segment and hub culture constitutes an easy, effective procedure for the conservative diagnosis of catheter colonization.

Bacteriological Techniques↗

PubMedDate not supplied

The prevalence of spondylolysis in the Spanish elite athlete.

The diagnosis of spondylolysis is a major cause of concern for patients and their families, especially when the patients are young athletes with promising futures in their sports. In this study, 3152 case histories of high-level athletes were evaluated to determine which sports had a higher prevalence of spondylolysis. The overall percentage of spondylolysis among athletes in this study (8.02%) was not very much higher than that among the general population, which varies between 3% and 7%. However, when each sport was considered separately we found much higher values for some sports, with the highest percentages occurring in throwing sports (26.67%), artistic gymnastics (16.96%), and rowing (16.88%). The analysis of the biomechanical movements involved in the sports with greater prevalence of spondylolysis has led us to include the element of torsion against resistance as another possible causative factor for spondylolysis that should be added to the already known causative mechanisms, lumbar hyperextension and rotation. We have divided the sports into three risk groups according to the prevalence of spondylolysis shown and the characteristics of the sample, and we recommend systematic radiological examination of the lumbar spine in athletes considered to be at greater risk of developing spondylolysis.

Adolescent↗

PubMedDate not supplied

[Neurology and the reform of the health care system in Colombia].

INTRODUCTION AND OBJECTIVES: Despite the magnitude of the Colombian health system reform, introduced in 1993, changes in specialized medical practice have not been evaluated. This paper is the follow-up of a similar study on the practice of neurology done by the authors before the reform. MATERIAL AND METHODS: Of the 62 members of the Colombian Association of Neurology living in Bogotá, 47 (76%) of them responded an anonymous survey inquiring on the characteristics of their medical practice and registering all the medical encounters during one week in October 1998. RESULTS: Two thirds of the total working time is devoted by neurologists to clinical work. Half of the neurologists in the sample have invested in diagnostic equipment. There was no significant change in the total number of patients attended during the week, as compared with the 1993 study, and the diagnostic profile was similar. The proportion of private patients was significantly lower, while patients from prepaid medical schemes increased. Patients belonging to the Obligatory Health Plan, designed to cover lowest income population, and to prepaid medicine are not distributed homogeneously throughout all ages. The first year of life is particularly uncovered by the Obligatory Health Plan, while prepaid schemes do not address the problems of individuals age 60 or more. CONCLUSIONS: There has been a significant reduction in private practice compensated by an increase in prepaid medicine. There is no evidence of increased coverage for neurological disorders.

Adolescent↗

PubMedDate not supplied