Fluid volume kinetics of dilutional hyponatremia; a shock syndrome revisited

OBJECTIVE: To evaluate whether the pathophysiology of shock syndromes can be better understood by comparing central hemodynamics with kinetic data on fluid and electrolyte shifts. METHODS: We studied the dilutional hyponatremic shock that developed in response to overhydration with electrolyte-free irrigating fluid - the so-called ‘transurethral resection syndrome' - by comparing cardiac output, arterial pressures, and volume kinetic parameters in 17 pigs that were administered 150 ml/kg of either 1.5% glycine or 5% mannitol by intravenous infusion over 90 minutes. RESULTS: Natriuresis appeared to be the key factor promoting hypovolemic hypotension 15-20 minutes after fluid administration ended. Excessive sodium excretion, due to osmotic diuresis caused by the irrigant solutes, was associated with high estimates of the elimination rate constant (k10) and low or negative estimates of the rate constant describing re-distribution of fluid to the plasma after translocation to the interstitium (k21). These characteristics indicated a high urinary flow rate and the development of peripheral edema at the expense of plasma volume and were correlated with reductions in cardiac output. The same general effects of natriuresis were observed for both irrigating solutions, although the volume of infused 1.5% glycine had a higher tendency to enter the intracellular fluid space. CONCLUSION: Comparisons between hemodynamics and fluid turnover showed a likely sequence of events that led to hypovolemia despite intravenous administration of large amounts of fluid. .

Efetividade de diferentes estratégias de intervenção com ferro nos níveis de hemoglobina e ferritina em escolares de Teresina, Piauí, Brasil / Effectiveness of different iron supplementation strategies on hemoglobin and ferritin levels among schoolchildren in Teresina, Piauí State, Brazil

O estudo avaliou o efeito das intervenções com sulfato ferroso e com ferro bisglicina quelato nas concentrações de hemoglobina e ferritina sérica em escolares de 7-11 anos, de ambos os sexos, de Teresina, Piauí, Brasil. Foi desenvolvido ensaio clínico-comunitário, randomizado, envolvendo 138 escolares, com níveis de hemoglobina < 11,5g/dL, alocados, individualmente, em dois grupos de tratamento. Um grupo (n = 71) recebeu 40mg de sulfato ferroso, uma vez/semana, e o outro (n = 67) 3,8mg de ferro bisglicina quelato, fracionados em biscoitos consumidos três vezes/semana, durante oito semanas. Houve um incremento (p < 0,01) médio, nas concentrações de hemoglobina, de 1,1g/dL entre os escolares que receberam sulfato ferroso e de 0,9g/dL para aqueles que receberam ferro bisglicina quelato, embora sem diferença (p > 0,05) na comparação intergrupos. Nenhum impacto foi observado (p > 0,05) nas reservas corporais de ferro. Entretanto, escolares que apresentaram depleção das reservas corporais de ferro (< 15ng/mL), no início dos tratamentos, tiveram aumento (p < 0,01) nas concentrações médias de ferritina sérica, após a intervenção, embora com efeito similar (p > 0,05) entre os grupos de tratamento. Os resultados confirmam a efetividade das intervenções e ratificam o uso do esquema semanal com sulfato ferroso e com ferro bisglicina quelato no tratamento da deficiência do mineral e da anemia ferropriva.

This study evaluated the effectiveness of supplementation with ferrous sulfate and iron bis-glycinate chelate on hemoglobin and serum ferritin levels among schoolchildren (7-11 years) of both sexes. A randomized community-based trial including 138 anemic children (hemoglobin < 11.5g/dL) was conducted in Teresina, Piauí State, Brazil. Children were assigned to two treatment groups on an individual basis. One group (n = 71) received 40mg iron as ferrous sulfate once weekly and the other group (n = 67) received 3.8mg of iron bis-glycinate chelate-enriched cookies, 3x/week, for 8 weeks. The interventions showed a significant increase (p < 0.01) in hemoglobin levels (1.1g/dL) for children who received ferrous sulfate and 0.9g/dl in those who received iron bis-glycinate chelate, although not significant in the inter-group comparison (p > 0.05). No effect was observed on body iron for either intervention (p > 0.05). Children with depleted iron stores (< 15ng/mL) at the beginning of interventions showed increased serum ferritin concentrations after 8 weeks (p < 0.01), although no difference between treatments (p > 0.05) was observed. The results confirm the effectiveness of the iron supplementation interventions and corroborate the use of iron salts or ferrous bisglycinate chelate on a weekly basis to overcome iron deficiency and anemia.