Clinical assessment of primary and secondary hypertension in children and adolescents.

The aim of this study was to compare the clinical features of patients with elevated blood pressure and to detect variables associated with the diagnosis of primary hypertension. We identified 383 (69%) hypertensive children (197 [51.5%] with primary hypertension, and 186 [48.5%] with secondary hypertension) out of 553 children referred to our clinic with a history of elevated blood pressure. The primary hypertension group was significantly older and had higher BMI, positive family history of hypertension, and lower prevalence of preterm birth compared with those with secondary hypertension. No difference was found between the two groups in terms of the frequency of target organ damage. Multiple regression analysis showed that a family history of hypertension, obesity, age over 10 years, elevated uric acid, and presence of higher systolic blood pressure values at admission were independent predictors of primary hypertension; therefore, these parameters can be considered important clues for diagnosing primary hypertension.

Algorithms to estimate PaCO2 and pH using noninvasive parameters for children with hypoxemic respiratory failure.

BACKGROUND: Ventilator management for children with hypoxemic respiratory failure may benefit from ventilator protocols, which rely on blood gases. Accurate noninvasive estimates for pH or P(aCO2) could allow frequent ventilator changes to optimize lung-protective ventilation strategies. If these models are highly accurate, they can facilitate the development of closed-loop ventilator systems. We sought to develop and test algorithms for estimating pH and P(aCO2) from measures of ventilator support, pulse oximetry, and end-tidal carbon dioxide pressure (P(ETCO2)). We also sought to determine whether surrogates for changes in dead space can improve prediction. METHODS: Algorithms were developed and tested using 2 data sets from previously published investigations. A baseline model estimated pH and P(aCO2) from P(ETCO2) using the previously observed relationship between P(ETCO2) and P(aCO2) or pH (using the Henderson-Hasselbalch equation). We developed a multivariate gaussian process (MGP) model incorporating other available noninvasive measurements. RESULTS: The training data set had 2,386 observations from 274 children, and the testing data set had 658 observations from 83 children. The baseline model predicted P(aCO2) within ± 7 mm Hg of the observed P(aCO2) 80% of the time. The MGP model improved this to ± 6 mm Hg. When the MGP model predicted P(aCO2) between 35 and 60 mm Hg, the 80% prediction interval narrowed to ± 5 mm Hg. The baseline model predicted pH within ± 0.07 of the observed pH 80% of the time. The MGP model improved this to ± 0.05. CONCLUSIONS: We have demonstrated a conceptual first step for predictive models that estimate pH and P(aCO2) to facilitate clinical decision making for children with lung injury. These models may have some applicability when incorporated in ventilator protocols to encourage practitioners to maintain permissive hypercapnia when using high ventilator support. Refinement with additional data may improve model accuracy.

Rifampicin carrying poly (D,L-lactide)/poly(ethylene glycol) microspheres: loading and release.

The aim of this study is to prepare rifampicin-loaded poly (D,L-lactide)/poly(ethylene golycol) (PDLLA/ PEG) copolymer microspheres as an injectable drug delivery system. PDLLA homopolymers with three different molecular weights (9,760, 14,540, and 23,050 daltons) were synthesized and then transesterified with PEG (with a molecular weight of approximately 3,300-4,000 daltons). By changing the ratio of PEG to PDLLA, block copolymers with different chain structures were synthesized. PDLLA and PDLLA/PEG microspheres in the size range of 2-10 microns were prepared by a modified solvent evaporation technique with the use of methylene chloride as the solvent and methyl cellulose as the emulsifier within the aqueous dispersion medium. Rifampicin was loaded within the microspheres during particle formation. Effects of the solvent/polymer and drug/polymer ratios, PDLLA molecular weight, and PEG content on drug loading and release were investigated. High drug loadings up to 100 mg rifampicin/g polymer were achieved. Both size and drug loadings were decreased by an increase in the solvent/polymer ratio and PEG content and by a decrease in the drug/polymer ratio and PDLLA molecular weight. High release rates were observed in the first 5 days after which constant and slow release rates were noted. Drug release was decreased by a decrease in the solvent/polymer ratio and PEG content and by an increase in the drug/polymer ratio and PDLLA molecular weight.