Aquaporin-2 excretion and renal function during the 1st week of life in preterm newborn infants.

In many preterm infants, a characteristic pattern of fluid and electrolyte homeostasis occurs during the 1st week of life, consisting of three phases: prediuretic, diuretic, and postdiuretic. In this study, we evaluated the possible role of aquaporin-2 (AQP2) in renal concentrating ability and correlated it with other markers of the renal function in healthy preterm infants. Daily urine and spot blood samples were collected from 9 healthy preterm (32 +/- 1 weeks) infants at postnatal ages 1, 3, and 7 days. Urine and serum osmolality, creatinine, electrolytes, and AQP2 excretion were measured. All infants showed a significant (about 7%) weight loss on day 3 associated with a more than threefold increase in urine output without a significant change in fluid intake (diuretic phase). The creatinine clearance increased on day 3, indicating an increase in glomerular filtration rate. Interestingly, on day 3, the level of total excreted AQP2 (pmol/h) was significantly higher when compared to day 1 and day 7, and the same tendency was observed for urine osmolality. To conclude, the observed increase in urine osmolality and creatinine clearance during the diuretic phase, paralleled by an increase in total AQP2 excretion, suggests that AQP2 can contribute to the urinary concentrating ability early in postnatal life.

[Perinatal outcome of monochorionic and dichorionic twin gestations: a study of 775 pregnancies at Reunion Island]. / Morbidité et mortalité périnatale des jumeaux et influence de la chorionicité: expérience de 10ans dans le Sud-Réunion. Étude de 775 grossesses.

OBJECTIVES: To compare the perinatal mortality and morbidity of infants born from monochorionic versus dichorionic twin pregnancies (TP). PATIENTS AND METHODS: Retrospective, comparative study of monochorionic and dichorionic TP over 10 years in the south of Reunion Island. Information regarding demographic, gestational and perinatal variables of mothers and infants was collected from the hospital perinatal database. RESULTS: Six hundred and twenty dichorionic and 155 monochorionic TP were analyzed. In case of monochorionic TP, mothers had higher rates of pregnancy-related hypertension (OR=1.82, 95%CI=[1.02-3.29] ; P=0.03) and hospitalization (OR=1.48, 95%CI=[1.02-2.16]; P=0.03). Newborns from monochorionic TP had higher morbidity for : very preterm birth (birth before 33 weeks gestation) (OR=1.65, 95%CI=[1.02-2.66]; P=0.02), very low birth weight (birth weight<1500g) (OR=1.73, 95%CI=[1.57-3.13]; P<0.001), Apgar<7 at 1 minute (OR=1.76, 95%CI=[1.18-2.61]; P<0.01) and hospitalization (OR=2.08, 95%CI=[1.58-2.73]; P<0.001). Perinatal mortality was also significantly higher (OR=2.47, 95%CI=[1.54-3.94]; P<0.001), as well intrauterine fetal death (OR=3.96, 95%CI=[1.95-8.05]; P<0.001) CONCLUSION: This study confirms that few differences exist among dichorionic and monochorionic TP with regard to maternal morbidity, while neonatal morbidity and mortality are higher in twins born from monochorionic pregnancies.

Neonatal problems of late and moderate preterm infants.

Late and moderate preterm infants account for >80% of premature births. These newborns experience considerable mortality and morbidity in comparison with full-term born infants. The purpose of this paper is to summarise the most common morbidities of late and moderate preterm infants in the neonatal period, their incidence, severity, risk factors and need for admission to the different levels of care. The recent findings on preventive strategies and management priorities for clinical care of these vulnerable babies are also reviewed.

Hypoproteinemia on the first day of life and adverse outcome in very preterm infants admitted to the neonatal intensive care unit.

OBJECTIVE: We aimed to investigate the relationship between day-1 hypoproteinemia and severe adverse outcome (SAO) in very preterm infants admitted to the neonatal intensive care unit (NICU). STUDY DESIGN: Retrospective study of all patients born from 24 to 31 weeks gestation and cared for in our NICU over an 8-year period. Infants were excluded if the serum protein value on the first day of life was not available. RESULT: A total of 913 patients were included. In all, 14.6% presented with SAO (death or severe neurological injury on cranial ultrasound). Hypoproteinemia (total protein level <40 g l(-1)) on day 1 of life occurred in 19.5 % of all patients. The rate of SAO was 33.7% in patients with hypoproteinemia and 9.9% in those with normoproteinemia (P<0.0001). Logistic and multiple regression analysis confirmed that the association hypoproteinemia-SAO remained significant after adjustment for the other major predictors of outcome present at baseline (odds ratio 3.4; 95% confidence interval 2.1-5.4; P<0.0001). CONCLUSION: Hypoproteinemia was highly associated with SAO in this cohort of critically ill preterm infants. We are unable to explain the link between hypoproteinemia and adverse outcome in our population. This investigation serves as a hypothesis-generating report of a large preterm infants sample, and suggests the need to assess the predictive accuracy for adverse outcome of hypoproteinemia in future prospective studies.

The effect of parenteral nitrogen and energy intake on electrolyte balance in the preterm infant.

BACKGROUND/OBJECTIVES: Recent guidelines for preterm parenteral nutrition (PN) recommend an earlier and higher intake of amino acids (AA) and energy to avoid postnatal catabolism and approximate normal fetal growth. Few investigations explored how early PN may affect electrolyte and water homeostasis. We performed a prospective observational trial to assess the effect of nutrient intake on electrolyte homeostasis and balance. SUBJECTS/METHODS: During 16 months, all infants ≤32 weeks were eligible. In the first week of life, we recorded the following daily: electrolytes (plasma and 8-h urine collection), nutritional intake, urine output, body weight, and we calculated sodium (Na) and potassium (K) balance. Infants were divided, for analysis, into three groups of AA intake: low <1.5 g/kg/day (LAA), medium 1.5-2 g/kg/day (MAA) and high >2 g/kg/day (HAA). RESULTS: A total of 154 infants were included. HAA group presented lower weight loss. Na balance was influenced by urine output and postnatal age, with little contribution of nutrition. Kalemia and K balance were mainly influenced by AA intake. K balance differed among groups: LAA, -2.3 mmol/kg/week; MAA, 1.1 mmol/kg/week; and HAA 2.6 mmol/kg/week (P<0.0001). In the HAA group, plasma and urine K were significantly lower and non-oliguric hyperkalemia was reduced. CONCLUSIONS: Na homeostasis was very slightly modified by early nutrition, suggesting that a negative Na balance is obligatory after birth. We showed that AA intake strongly affects K balance, minimize hyperkalemia and reduces weight loss. As K balance is strictly linked to cellular metabolism, we speculate that early nutrition may inhibit cellular catabolism and reduce the contraction of intracellular water compartment.

Fluid and electrolyte intake during the first week of life in preterm infants receiving parenteral nutrition according current guidelines.

There is growing evidence that early water and electrolyte homeostasis may be influenced by energy balance in preterm infants. Some fluid and electrolyte disturbances of postnatal life could be in part promoted by the catabolism due to withheld amino acid and energy supply after birth. According to current guidelines parenteral nutrition with relatively high protein and lipid needs is commenced on day one. By turning the nitrogen balance from negative to zero or even positive, amino acid administration could also minimize the occurrence of water and ions disturbances after birth especially in extremely preterm infants. Future researches are needed in order to further investigate the impact of amino acid and energy intake on early fluid balance in preterm infants.

Aquaporin-2 urinary excretion in preterm infants: relationship to diuresis and vasopressin.

AIMS: Few investigations have explored the urinary aquaporin-2 (u-AQP2) excretion pattern after birth in preterm infants with conflicting results regarding the correlation between u-AQP2, urinary osmolality and vasopressin. The aims of this study were to evaluate u-AQP2 excretion during the first week of life in preterm infants, to correlate u-AQP2 with other markers of renal function and to investigate the relationship between u-AQP2, urinary tonicity and arginine-vasopressin in the immature kidney. METHODS: In infants born less than 33 weeks daily diuresis, u-AQP2, urinary arginine-vasopressin, urine and plasma tonicity, creatinine and electrolytes were measured through the first 7 days of life. RESULTS: Fifty-five infants were evaluated. u-AQP2 excretion showed the following profile: the highest u-AQP2 levels were found on day 2 and values remained significantly higher until day 5 with respect to day 1. On day 6, u-AQP2 levels significantly decreased to values closer to those found on day 1. u-AQP2 excretion was not associated with arginine-vasopressin while significant, but weak association was found with urinary tonicity (r = -0.20; -0.32 < r < -0.11; P < 0.05). u-AQP2 excretion and creatinine clearance were significantly associated during the study period (r = 0.19; 0.08 < r < 0.29; P < 0.05). There was a strong association between totally u-AQP2 excretion and diuresis over the week (r = 0.72; 0.66 < r < 0.76; P < 0.0001). CONCLUSION: Significant variations occur in AQP2 expression levels during the first week of life in preterm infants. AQP2 does not seem to contribute to the urinary concentration ability after birth. Further investigations are required to elucidate the mechanisms underlying the strong association between diuresis and u-AQP2 excretion in early postnatal life.

[Urinary tract infections in children]. / Infections urinaires en pédiatrie.

Urinary tract infection (UTI) is relatively frequent in children. The younger the child is, the more symptoms are atypical. UTI is often associated with functional or malformative uropathy, such as vesico-ureteral reflux or obstruction. Appropriate imaging studies should be carried out in every infected child. The prognosis of uncomplicated UTI is very good, but is less favorable when the UTI is associated with urological abnormalities. Development of pyelonephritic scars can lead to kidney scarring, for which the occurrence of intrarenal reflux is probably responsible . Short-term treatment is recommended for uncomplicated UTI. Uncomplicated UTI with frequent relapses requires prophylactic chemotherapy; this treatment should also be considered when UTI is associated with vesico-ureteral reflux. Surgery is indicated in the presence of major urological malformations. Whether medical or surgical, the treatment of UTI should be followed by urine cultures whenever the child presents with fever. The antibiotic treatment of acute pyelonephritis must be started immediately, preferentially by intravenous route. A switch to oral treatment can be made after obtaining the results of the antibiogram. UTI represents a major risk in neonates; it should preferably be managed in specialized centers.

Factors affecting postnatal changes in serum creatinine in preterm infants with gestational age <32 weeks.

OBJECTIVE: The Aim of this study was to investigate maternal and neonatal factors associated with serum creatinine (SeCr) changes in a representative cohort of preterm newborns during their first week of life. STUDY DESIGN: Retrospective study. All the infants born less than 32 weeks of gestational age (GA) and cared for in our neonatal intensive care unit between January 2001 and December 2005 were eligible for the analysis. Epidemiological data of all mother-infant pairs and neonatal SeCr values were recorded. RESULT: A total of 652 infants were studied. Multivariate regression analysis showed that the main independent factors associated with high SeCr at day 1 were hypertensive disease of pregnancy (P<0.0001) and advancing hour of life (P<0.0001), with minimal contribution of placental abruption (P<0.05) and higher GA (P<0.05). Lower GA (P<0.0001) and ibuprofen-treated patent ductus arteriosus (PDA; P<0.0001) were the main analyzed factors independently associated with higher SeCr peak (defined as the highest SeCr during the week), with less contribution of respiratory distress syndrome (P<0.01) and early onset infection (P<0.05). In infants with hemodynamically significant PDA (hsPDA) SeCr before ibuprofen administration was higher when compared to GA-matched controls without hsPDA (P< 0.0001). CONCLUSION: SeCr peak was inversely correlated to GA in preterm infants born less than 32 weeks of GA. Neonatal rather than maternal morbidity affected SeCr peak. In hsPDA, SeCr increase preceded ibuprofen administration.

Early low-dose hydrocortisone in very preterm infants: a randomized, placebo-controlled trial.

BACKGROUND: Several reports indicate a decreased cortisol response to adrenocorticotropic hormone in preterm infants developing chronic lung disease and in preterm infants with refractory hypotension. Low-dose hydrocortisone (HC) may allow for beneficial effects. OBJECTIVE: Our aim was to assess whether HC is able to increase survival without chronic lung disease. METHODS: We performed a double-blind, randomized, placebo-controlled trial. Fifty mechanically ventilated infants (birth weight: 500-1,249 g) were randomized to receive treatment (HC 0.5 mg/kg/12 h for 9 days, then HC 0.5 mg/kg/24 h for 3 days) or placebo. Major outcome was survival without oxygen dependence at 36 weeks of postconceptional age (O(2)-free survival). RESULTS: The basic characteristics were similar between the two groups. O(2)-free survival was higher in the HC group (64 vs. 32%). The advantage was particularly evident among infants without antenatal steroids. The mortality rate was 16% in the HC group versus 40% in the control group (difference not significant). Hypotension after recruitment was reduced by HC (0 vs. 30%). The incidence of gastrointestinal perforation and other adverse effects was similar between the two groups. CONCLUSIONS: HC prophylaxis improved O(2)-free survival and early cardiocirculatory function in our population, without important short-term effects. The neurodevelopmental outcome will be assessed at 2 years.

[Significance of lactose breath test in the newborn]. / Significato del breath test al lattosio in età neonatale.

Lactose breath test have been performed in healthy newborns, in whom breath hydrogen excretion was preliminarily demonstrated by lactulose breath test. 27.5% of newborns showed positive lactose breath test, with no differences related to sex and gestational age, while a higher percentage of positive test has been found in < 2500 g and formula-fed neonates compared, respectively, to > or = 2500 g and breast-fed ones. In healthy newborns, without any clinical signs of lactose intolerance, it is possible to demonstrate hydrogen in expired air; this is not equivalent of lactose malabsorption, but, instead, depends on the phenomenon of colonic fermentation that allows energy and nutrient absorption.