Risk factors for intrahospital infection in newborns.

BACKGROUND: Intrahospital infection (IHI) in the newborn (NB) is a morbidity problem that increases mortality rates in this age group because the infecting microorganism is more aggressive. The objective of this study was to compare risk factors for localized or systemic IHIs between groups of NBs with and without IHIs. METHODS: This was a retrospective study of two groups of patient records from January 1995 to December 1998. Group A (cases) was made up of 73 patients with documented IHIs and Group B (controls), 105 patients without IHIs. Descriptive and inferential statistics (Student t, Mann-Whitney U, Wilcoxon rank sum, Chi square, and Fisher exact tests) were used. Odds ratio (OR) and multiple logistic regression were used to study risk factors. Statistical significance was considered at p <0.05. RESULTS: Average gestational age was 35.4 +/- 4.3 weeks in Group A patients and 37.4 +/- 3.2 weeks for Group B patients with p = 0.001. Risk factors studied by means of OR (low birth weight, prematurity of 30 weeks of gestational age or less, prolonged intrahospital stay, etc.) showed statistical significance. Also showing significance were other not-well-studied factors such as higher numbers of diagnoses and blood transfusions. After multivariate analysis, the group of risk factors more associated with IHIs included vein dissection for insertion of central venous catheter, orotracheal intubation, and prolonged intrahospital stay (12 days or more) with an accumulative r of 0.6112. CONCLUSIONS: We conclude that there are several known risk factors for IHIs and others not well described to date that must be avoided to the extent possible in the NB, particularly in the premature newborn population.

Detection of transitory myocardial ischemia secondary to perinatal asphyxia.

Transitory myocardial ischemia (TMI) is seen as a complication of severe asphyxia. Its presentation is variable, ranging from tachypnea to cardiogenic shock, and it is often masked by the predominant disease. The objective of this study was to detect TMI secondary to perinatal asphyxia in a population of asphyxiated newborns (NB) in comparison with asphyxiated NB with no evidence of TMI. From April 1996 to December 1997, 43 asphyxiated (stressed) NB were studied. Three were excluded. Patients were placed into two groups: Group A with TMI (n = 33) and Group B without TMI (n = 7). No significant differences were found in gestational age, birth weight, extrauterine age, Apgar score, or total creatine phosphokinase values between the two groups. Differences were found in CPK-MB levels and in ischemic electrocardiographic changes and blockages, especially for Group A. In this group, only 24 (72.7%) were cardiovascularly symptomatic. We conclude that TMI secondary to perinatal asphyxia is more frequent than has been reported. Thus, it would be useful in all asphyxiated NB to measure CPK-MB isoenzyme activity and patients can then be submitted to an electrocardiogram for detection in order to offer opportune treatment when required.

Hemodynamic indexes in newborns using the arteriovenous oxygen content difference.

OBJECTIVE: To determine in peripheral blood samples of newborns (NB) cardiac output (Q), cardiac index (CI), systemic vascular resistance index (SVRI), and effective oxygen transport (EO2T), through arteriovenous oxygen content difference ([C(a-v) O2]). DESIGN: Comparative survey. SETTING: Healthy NBs and NBs in intermediate care in third level medical attention units. MATERIAL AND METHODS: Forty-seven NB (17 pre-term) were prospectively studied in August and September/1995. A blood sample of 0.4 mL was taken from the umbilical or femoral vein and from the umbilical, radial or femoral artery. The inferencial statistics were done with a t test and Pearson's correlation coefficient. Significance was considered if p < 0.05. RESULTS: Cardiac output ranged from 0.3 to 1.4, mean = 0.6 L/min +/- 0.24 (+/- SD); CI ranged from 1.8 to 6.4 L/min/m2 body surface area (mean = 3.3 +/- 1.2); SVRI ranged from 533 to 2,391 dyne/sec/cm-5/m2 BSA (mean = 1,317 +/- 494); EO2T ranged from 307 to 1,017 mL/min/m2 BSA (mean = 549 +/- 186); the [C(a-v) O2] ranged from 3.1 to 10.7% in volume (mean = 6.8 +/- 2.1). No significant differences were found in Q between pre-term and full-term NB nor was there any correlation between Q and gestational age. CONCLUSIONS: The [C (a-v)O2] is a good alternative to obtain indexes in peripheral blood of NB without cardiopathy, whenever other less invasive and more sophisticated methods are unavailable. In order to calculate the indexes in critically-ill patients, it is necessary to measure O2 consumption prior to applying this method.

Usefulness of fractional excretion of sodium in critically ill pre-term newborns.

The purpose of this prospective study was to measure the fractional excretion of sodium (FENa) in critically ill pre-term newborns (PTNB) in order to determine its cut point in the diagnosis of acute renal failure (ARF). This study included 52 newborns and was conducted from May, 1994 to May, 1995. Patients were divided in two groups: patients without ARF in group A (n = 47) and patients with ARF in group B (n = 5). No statistically significant differences were found in birth weight, extrauterine life span, serum sodium levels, urine creatinine and urinary volumes between the two groups, but there was a difference in gestational age, urinary sodium concentration and serum creatinine levels. Sensitivity and specificity were determined, and the critical level of FENa was 4% or greater for ARF diagnosis. The average FENa value for Group A was 1.4 +/- 1.4% with a median of 0.92%. In Group B, average FENa was 6.9 +/- 2.9% with a median of 8.5% (P < 0.001). We conclude that FENa is a valuable tool for the assessment of renal function in critically-ill PTNB, in spite of all other factors present in this population that could modify its values.