Comparison between measured and fick-derived values of hemodynamic and oxymetric variables in patients with acute myocardial infarction.

PURPOSE: Previous studies have compared the relationship between directly measured values for cardiac output, systemic oxygen consumption (VO2), and arteriovenous oxygen difference (D(A-v)O2) with those calculated by the Fick principle. However, the validity of Fick's principle in critically ill patients undergoing physiologic changes and pharmacologic interventions is unknown. The purpose of our study was to compare directly measured values for hemodynamic and oxymetric variables with those calculated by the Fick equation in patients with acute myocardial infarction, at baseline and after the hemodynamic changes produced by pharmacologic interventions. PATIENTS AND METHODS: Cardiac output, (VO2), and (D(A-v)O2) were measured in 33 patients with acute myocardial infarction, at baseline (50 +/- 30 hours after the onset of symptoms) and after pharmacologic intervention to relieve pulmonary congestion. These values were then compared with indirect values derived from the Fick equation. RESULTS: High and significant correlations were found between thermodilution and Fick-derived cardiac output at baseline (r = 0.91, p less than 0.001) and post-intervention (r = 0.92, p less than 0.001). Similarly, VO2 values measured by expired gas analysis showed a significant correlation with VO2 calculated by the Fick principle, at baseline (r = 0.85, p less than 0.001) and post-intervention (r = 0.84, p less than 0.001). Lastly, when D(A-v)O2 of arterial and mixed venous samples was measured by spectrophotometry and compared with calculated values, there was a significant correlation at baseline (r = 0.85, p less than 0.001) and after intervention (r = 0.85, p less than 0.001). Analysis of variance revealed no difference between measured and calculated values for the three variables under those two conditions. CONCLUSION: In patients with acute myocardial infarction, cardiac output, VO2, and D(A-v)O2 indirectly calculated by the Fick principle are equivalent to directly measured values, despite the various degrees of hemodynamic dysfunction and the currently used therapeutic interventions.

Chernobyl-related thyroid cancer in children of Belarus: a case-control study.

The accident at the Chernobyl nuclear power plant on April 26, 1986, released approximately 2 EBq of 131I and other radioiodine isotopes that heavily contaminated southern Belarus. An increase in thyroid cancer reported in 1992 and attributed to the Chernobyl accident was challenged as possibly the result of intensive screening. We began a case-control study to test the hypothesis that the Chernobyl accident caused the increase in thyroid cancer. Records of childhood thyroid cancer in the national therapy centers in Minsk in 1992 yielded 107 individuals with confirmed pathology diagnoses and available for interview. Pathways to diagnosis were (1) routine endocrinological screening in 63, (2) presentation with enlarged or nodular thyroid in 25 and (3) an incidental finding in 19. Two sets of controls were chosen, one matched on pathway to diagnosis, the other representing the area of heavy fallout, both matched on age, sex and rural/urban residence in 1986. The 131I dose to the thyroid was estimated from ground deposition of 137Cs, ground deposition of 131I, a data bank of 1986 thyroid radiation measurements, questionnaires and interviews. Highly significant differences were observed between cases and controls (both sets) with respect to dose. The differences persisted within pathway to diagnosis, gender, age and year of diagnosis, and level of iodine in the soil, and were most marked in the southern portion of the Gomel region. The case-control comparisons indicate a strong relationship between thyroid cancer and estimated radiation dose from the Chernobyl accident.

Prognostic value of clinical markers of reperfusion in patients with acute myocardial infarction treated by thrombolytic therapy.

Patients who cannot be reperfused after thrombolytic therapy have a high mortality rate. Noninvasive clinical markers of reperfusion have been widely studied, yet their prognostic significance remains unclear. To assess the prognostic value of commonly used noninvasive clinical markers of early reperfusion we studied 327 patients who received intravenous thrombolytic treatment (1.5 MU streptokinase in 1 hour or 100 mg alteplase in 3 hours) within 6 hours of acute infarction. Successful clinical reperfusion (SCR) was defined as the presence of at least two of the following criteria at 2 hours after thrombolytic treatment: (1) significant relief of pain (a 5-point reduction on a 1 to 10 subjective scale), (2) > or =50% reduction of sum of ST segment elevation, and (3) abrupt initial increase of creatine kinase levels (more than twofold over the upper-normal or baseline elevated values). Clinical variables that were significantly associated by univariate analysis were tested by multivariate analysis to obtain independent predictors of 30-day mortality rate. SCR was present in 210 (64%) patients (group 1), and absent in 117 (36%) patients (group 2). The groups were similar for most baseline characteristics, although group 2 patients were slightly older (mean 60 vs 57 years, p < 0.02). Thirty-day outcomes for group 2 patients compared with group 1 patients were heart failure in 23.1% and 10.5% (p < 0.005), progression to cardiogenic shock in 12.8% and 0.5%, (p < 0.00001), and death in 16.2% and 3.8% (p < 0.0001), respectively. By multivariate analysis the Killip class at admission (p < 0.00001), the absence of SCR (p = 0.017), anterior infarct location (p = 0.021), and age (p = 0.03) were independent predictors of mortality rate, and sex (p = 0.051) had borderline significance. The absence of SCR defined a group of patients with significantly higher mortality rate (odds ratio 4.89, 95% confidence interval 2.07 to 11.57). Three simple noninvasive clinical criteria of successful reperfusion may be used to identify a group of patients with poor prognosis after thrombolytic therapy in whom alternative strategies could be applied.

Evaluacion del sistema nervioso central por medio de potenciales evocados en el Sindrome de Sjagren primario / Central nervous system evaluation by evocated potentials in primary Sj gren Syndrome

El Sindrome de Sjagren primario es una exocrinopatia cronica autoinmune con manifestaciones clinicas sistamicas entre las que se incluyen el compromiso del sistema nervioso. Los potenciales evocados son uno de los m todos utilizados para evaluar a nivel del Sistema Nervioso Central la integridad del circuito neuronal desde la periferia a la corteza cerebral. Representan la respuesta del sistema nervioso central a un estimulo sensorial generando una secuencia de señales electricas pequeñas, que de acuerdo al lugar y tipo de estimulo, permiten explorar diferentes localizaciones y arribos del neuroeje. Se evaluaron potenciales evocados auditivos de tronco (PEAT), cognitivos (P300), visuales (PEV), electroretinograma por inversion de damero (ERG) y somatosensitivas de tibial posterior (PESS) en una poblacion de 17 pacientes con Sindrome de Sjagren primario segun criterios de Skopouli. Todos los pacientes fueron del sexo femenino con una edad media de X 53,7 años y un tiempo medio de evolucion en la enfermedad de 5,8 años. Se compararon los resultados con grupos controles; los hallazgos mostraton diferencias altamente significativas en el tiempo de conduccion medular y central (PESS) y en la amplitud de la onda (PEAT) y discretamente significativa en la latencia de la onda P100 (PEV) (P=9,045), siendo el resto de las variables no significativas. Concluimos que estos pacientes tienen una conduccion medular significativa a nivel del nervio optico, debiandose considerar la baja amplitud de la onda V auditiva (PEAT). Queda a discusion el valor de estos hallazgos en relacion con el Sindrome de Sjagren primario