Assessment of Thrombelastography and Platelet Life Span in Ovines.

Ovines are a common animal model for the study of cardiovascular devices, where consideration of blood biocompatibility is an essential design criterion. In the ovine model, tools to assess blood biocompatibility are limited and continued investigation to identify and apply additional assays is merited. Toward this end, the thrombelastograph, clinically utilized to assess hemostasis, was used to characterize normal ovine parameters. In addition, platelet labeling with biotin was evaluated for its potential applicability to quantify ovine platelet life span. Mean ovine thrombelastograph values were reaction-time: 4.9 min, K-time: 2 min, angle: 64.1°, maximum amplitude: 68.6mm, actual clot strength: 11.9 kd/s, and coagulation index: 1.5. Reaction time was significantly shorter and maximum amplitude, actual clot strength, and coagulation index were all significantly higher when compared to normal human thrombelastograph values suggesting some hypercoagulability of sheep blood. Biotinylation and reinfusion of ovine platelets allowed temporal tracking of the labeled platelet cohort with flow cytometry. These data indicated a mean ovine platelet life span of 188h with a half-life of 84h. The collection of these parameters for normal ovines demonstrates the applicability of these techniques for subsequent studies where cardiovascular devices may be evaluated and provides an indication of normal ovine values for comparison purposes.

New-Generation Thromboelastography: Comprehensive Evaluation of Citrated and Heparinized Blood Sample Storage Effect on Clot-Forming Variables.

CONTEXT: - Thromboelastography (TEG) is a whole blood, real-time analyzer measuring the viscoelastic properties of the hemostasis process and allowing for individualized goal-directed therapy. However, routine use of TEG requires validation of sample storage effect on clot parameters. OBJECTIVES: - To establish the minimum time required for equilibration time and the maximum time for sample storage for all commercially available TEG tests for the new-generation TEG 6s and to determine how those times compare with the older generation TEG 5000. DESIGN: - Citrated and heparinized whole blood samples obtained from 20 healthy donors were analyzed for clot parameters at multiple time points for both the TEG 6s and the TEG 5000. Samples were activated with the citrated multichannel cartridge or the platelet-mapping cartridge in the TEG 6s or with recalcified kaolin in the TEG 5000. RESULTS: - All blood samples yielded TEG parameter results within reference ranges and had a tendency toward hypercoagulable profiles with increased storage time. Sample storage resulted in increased platelet inhibition with significant differences at 4 hours in the platelet-mapping cartridge (arachidonic acid percentage of inhibition, P = .002; adenosine diphosphate percentage of inhibition, P = .02). CONCLUSIONS: - For nonemergent cases or in a central laboratory setting, all tests provided reliable results for up to 4 hours in the citrated multichannel cartridge and for 3 hours for platelet function information in the platelet-mapping cartridge. In emergent/urgent situations in which the sample needs to be run immediately, RapidTEG and functional fibrinogen tests may be preferred.

Shaking rigors in parturients.

OBJECTIVE: To describe the frequency, duration and timing of shaking rigors during parturition and their associations with several clinical variables. STUDY DESIGN: A total of 467 term, singleton paturients at a single hospital over a 13-month recruitment period were observed by their labor nurses for shaking rigors. Thirteen clinical variables, including length of labor, were also recorded. Multiple regression procedures were used to evaluate associations with presence or absence, number and total duration of rigors. The relationship in time between shaking rigors and sentinel events in labor was also examined. With this sample size, we had > 80% power to detect differences as small as 0.26 effect size units for continuous measures, or ORs of 1.75 or greater for categorical measures, when comparing patients with and without rigors. RESULTS: In total, 57% of parturients experienced at least 1 rigor. Epidural usage was related to risk, duration and number of rigors. Increased maximum temperature was associated with an increased chance of rigors. Epidural, birth and maternal fever were antecedent events. CONCLUSION: Over half of parturients experienced shaking rigors. Epidural administration and fever were associated with an increased probability of rigors and an increased number of episodes.

Reducing high-order perineal laceration during operative vaginal delivery.

OBJECTIVE: This study was undertaken to assess the impact of a focused intervention on reducing high-order (third and fourth degree) perineal lacerations during operative vaginal delivery. STUDY DESIGN: The following recommendations for clinical management were promulgated by departmental lectures, distribution of pertinent articles and manuals, training of physicians, and prominent display of an instructional poster: (1) increased utilization of vacuum extraction over forceps delivery; (2) conversion of occiput posterior to anterior positions before delivery; (3) performance of mediolateral episiotomy if episiotomy was deemed necessary; (4) flexion of the fetal head and maintenance of axis traction; (5) early disarticulation of forceps; and (6) reduced maternal effort at expulsion. Peer comparison was encouraged by provision of individual and departmental statistics. Clinical data were extracted from the labor and delivery database and the medical record. RESULTS: One hundred fifteen operative vaginal deliveries occurred in the 3 quarters preceding the intervention, compared with 100 afterward (P = .36). High-order laceration with operative vaginal delivery declined from 41% to 26% (P = .02), coincident with increased use of vacuum (16% vs 29% of operative vaginal deliveries, P = .02); fewer high-order lacerations after episiotomy (63% vs 22%, P = .003); a nonsignificant reduction in performance of episiotomy (30% vs 23%, P = .22); and a nonsignificant increase in mediolateral episiotomy (14% vs 30% of episiotomies, P = .19). CONCLUSION: Introduction of formal practice recommendations and performance review was associated with diminished high-order perineal injury with operative vaginal delivery.

Bone density changes in women who receive thromboprophylaxis in pregnancy.

OBJECTIVE: The purpose of this study was to compare unfractionated heparin therapy to the low molecular weight heparin, enoxaparin sodium, and their effects on bone mineral density over the course of pregnancy. STUDY DESIGN: Pregnant patients whose condition required thromboprophylaxis were recruited in this prospective randomized controlled trial and were assigned to receive either unfractionated heparin therapy or low molecular weight heparin therapy. Bone mineral density was measured by dual energy x-ray absorptiometry at the proximal femur on enrollment and again shortly after delivery. RESULTS: One hundred twenty women were enrolled, and 98 women completed the study. There was no difference in the change in bone mineral density at the femoral neck (P = .054) or total proximal femur (P = .584) between groups. Only 1 of 40 patients (2.5%) who received unfractionated heparin therapy and 1 of 49 patients (2.0%) who received low molecular weight heparin therapy (P = 1.0) experienced bone loss of > or = 10% at the femoral neck. CONCLUSION: In this study, the incidence of clinically significant bone loss (> or = 10%) in the femur in women who received thromboprophylaxis in pregnancy is approximately 2% to 2.5% and appears to be similar, regardless of whether the patient receives low molecular weight heparin therapy or unfractionated heparin therapy.

Complement, fetal antigen, and shaking rigors in parturients.

OBJECTIVES: To assess the relationship, if any, between complement, fetal antigen, and shaking rigors during labor and delivery. METHODS: We recruited 13 volunteers for serial blood sampling during labor and childbirth. RESULTS: Complement levels had a small but significant drop (11-15%) immediately following childbirth but had no association with fetal antigen levels or shaking rigors. Fetal antigen levels failed to show any consistent relationship with shaking rigors or the labor and delivery process. CONCLUSION: Shaking rigors do not appear to be associated with changes in either complement or fetal antigen levels. Complement levels remain stable during labor but drop immediately following birth.

Outcomes after expectant management of extremely preterm premature rupture of the membranes.

OBJECTIVE: This study was undertaken to assess contemporary outcomes in pregnancies managed expectantly after extremely preterm premature (< or =24 weeks) premature rupture of the membranes (EPPROM). STUDY DESIGN: We queried antepartum and ultrasound databases for patients with EPPROM. Data on pregnancy outcome and short-term neonatal outcomes were collected. RESULTS: Forty-six patients with EPPROM were studied. Patients were hospitalized at 24 weeks' gestation and given antibiotics and antenatal steroids. Median gestational age at PPROM was 22.0 weeks (range 16.9-24 weeks); 43 (93%) elected expectant management, 2 of whom later had an intrauterine fetal death. Median latency period to delivery was 13 days (range 0-96 days), with mean gestational age at delivery of 25.8+/-3.4 weeks. Overall survival was 47% (27 of 57 infants), after a median hospital stay of 71 days (range 17-209 days). Ten (37%) of the survivors have serious sequelae. CONCLUSION: Although significant pregnancy prolongation after previable PPROM occurs in many cases, neonatal outcomes remain poor.

Health literacy and pregnancy preparedness in pregestational diabetes.

OBJECTIVE: We investigated the association between functional health literacy and markers of pregnancy preparedness in women with pregestational diabetes. RESEARCH DESIGN AND METHODS: English- and Spanish-speaking pregnant women with pregestational diabetes were recruited. Women completed the Test of Functional Health Literacy in Adults (TOFHLA) short form and a questionnaire. A TOFHLA score of < or =30 was defined as low functional health literacy. RESULTS: Of 74 women participating in the study, 16 (22%) were classified as having low functional health literacy. Compared with women with adequate health literacy, those with low health literacy were significantly more likely to have an unplanned pregnancy (P = 0.02) and significantly less likely to have either discussed pregnancy ahead of time with an endocrinologist or obstetrician (P = 0.01) or taken folic acid (P = 0.001). CONCLUSIONS: The results of this study suggest that low functional health literacy among women with pregestational diabetes is associated with several factors that may adversely impact birth outcomes.

Prematurity in multiple gestations: identification of patients who are at low risk.

OBJECTIVE: The purpose of this study was to evaluate a strategy for the identification of patients with multiple gestations who are at low risk for preterm delivery. STUDY DESIGN: A prospective observational study among patients with twin and triplet gestations. At 20 and 24 weeks of gestation, screening for bacterial vaginosis and fetal fibronectin was performed, followed by digital and sonographic assessment of the cervix. The treating physicians were blinded to test results. RESULTS: At the 24-week examination, specificities for delivery at >32 weeks of gestation for digital examination (92.9%), fetal fibronectin level (93.9%), cervical length on sonographic scan (85.1%), and combined fetal fibronectin level and cervical length (81.3%) did not differ statistically. Negative predictive values for these tests were >or=95%. All tests performed better at 24 weeks of gestation than at 20 weeks of gestation. CONCLUSION: At 24 weeks of gestation, a normal digital examination, a negative fetal fibronectin level, a normal cervical length on sonographic scan, or the combination of a negative fetal fibronectin level and a normal cervical length each confer a similarly high likelihood of delivery at >32 weeks of gestation in women with multiple gestations.