Superior effect of hypertonic saline over mannitol to attenuate cerebral edema in a rabbit bacterial meningitis model.

OBJECTIVE: Adjunctive therapies that reduce the cerebral edema in bacterial meningitis include osmotic agents. There is a lack of information comparing mannitol vs. hypertonic saline as an osmotic agent for adjunctive therapy of bacterial meningitis. We attempted to elucidate the impact of hypertonic saline in cerebral edema in the setting of bacterial meningitis as well as to explore potential mechanisms of action. DESIGN: Randomized controlled in vivo study. SETTING: University research laboratory. SUBJECTS: Rabbits. INTERVENTIONS: A rabbit model of bacterial meningitis was used comparing 3% hypertonic saline with 20% mannitol as adjunctive therapy. MEASUREMENTS AND MAIN RESULTS: Adjunctive 3% hypertonic saline treatment persistently elevated mean arterial pressure as compared with the model or ampicillin group (p < .01). Although both 20% mannitol and 3% hypertonic saline efficiently elevated serum osmolality for almost 5 hrs (p < .01), 20% mannitol lowered intracranial pressure for only a short time (<2 hrs) and did not elevate cerebral perfusion pressure. Three percent hypertonic saline treatment efficiently lowered intracranial pressure and elevated cerebral perfusion pressure for almost 5 hrs (p < .01). Furthermore, 3% hypertonic saline treatment efficiently elevated serum Na+ concentration for >5 hrs (p < .01). Three percent hypertonic saline treatment was superior to 20% mannitol in lowering leukocyte number and protein content in cerebrospinal fluid (p < .01). Three percent hypertonic saline treatment reduced water content and Evans blue incorporation in the brain (p < .01). Three percent hypertonic saline treatment inhibited aquaporin 4 expression (p < .01) and attenuated pathologic brain damage more efficiently compared with adjuvant 20% mannitol treatment (p < .01). CONCLUSIONS: Adjunctive 3% hypertonic saline treatment significantly elevated mean arterial pressure, reduced intracranial pressure, greatly improved cerebral perfusion pressure, inhibited brain aquaporin 4 expression, reduced cerebral edema, and attenuated brain damage with a superior effect over 20% mannitol in a rabbit bacterial meningitis model.

[An epidemiologic survey on blood lead levels in preschool children living in towns of Hunan Province].

OBJECTIVE: To investigate blood lead levels (BLLs) and influencing factors of BLLs among preschool children living in towns of Hunan Province. METHODS: A total of 2 044 preschool children (1,108 boys and 936 girls) from towns of 12 regions in Hunan Province were enrolled by a cluster sampling between September 2008 and June 2009. The average age of the children was 4.4 ± 1.1 years (range 2 to 6 years). BLLs were determined using the atomic absorption spectrographic method. The influencing factors of BLLs were investigated using a standard questionnaire and logistic regression analysis. RESULTS: The mean BLLs of the children were 81.9 ± 34.5 µg/L. BLLs more than 100 µg/ L were noted in 482 children (23.58%). Of the 482 children, 472 (23.09%) showed BLLs of 100-199 µg/L and 10 (0.49%) showed BLLs ≥ 200 µg/L. There were significant differences in the prevalence of elevated BLLs (≥ 100 µg/L) among different age groups (P < 0.01). The prevalence of elevated BLLs in boys (28.99%) was significantly higher than that in girls (21.98%) (P < 0.01). There were significant differences in the prevalence of elevated BLLs in children from different regions (P < 0.01). The logistic regression analysis showed that the male (OR = 1.449, P < 0.01), father's occupational lead exposure (OR = 1.314, P < 0.01)and maternal frequent use of hair dyes (OR = 1.678, P < 0.05) were risk factor for elevated BLLs. CONCLUSIONS: The prevalence of elevated BLLs is higher in preschool children living in towns of Hunan Province and is associated with a child's region and age. The male, father's occupational lead exposure and maternal frequent use of hair dyes are risk factor for elevated BLLs.