Ehud Zmora

Heart rate variability in the neonate and infant: analytical methods, physiological and clinical observations

Naturally occurring oscillations in heart rate have long been considered to reflect the modulating influences of the autonomic nervous system. Individual reports of heart rate variability in healthy and sick neonates and infants have provided valuable information as to pathophysiological changes in autonomic cardiovascular control. It is evident that prematurity and poor health are reflected in attenuated heart rate variability. However, at present, there are few standard criteria for the analysis of heart rate variability, preventing precise comparisons among the various studies. Until recommendations for standardized analytical methods are made, clinical application of heart rate variability in neonatal and infant prognosis and therapy remains premature. □Heart rate variability, infant, maturation, neonate, power spectrum analysis, respiratory distress, sleep state, sudden infant death syndrome

Pseudohypoaldosteronism in a preterm infant: Intrauterine presentation as hydramnios

After a pregnancy complicated by severe hydramnios, a preterm infant had clinical and biochemical evidence of pseudohypoaldosteronism. Fetal polyuria probably caused the hydramnios.

Fetal growth and postnatal growth failure in very-low-birthweight infants

Aim: To determine in a cohort of very‐low‐birthweight (VLBW) infants the incidence of postnatal growth failure and the influence of intrauterine growth and neonatal morbidities on the risk for severe postnatal growth failure (PNGF). Methods: The study was based on analysis of data from the Israel Neonatal Network database on VLBW infants born between 1995 and 2001. Z‐score was determined for weight at birth and discharge, and severe PNGF was defined as a decline in z‐score of greater than 2. Univariate analysis and multi‐linear regression determined the effect of fetal growth and neonatal morbidities on the risk for severe PNGF. Results: Severe PNGF occurred in 10.6% of the cohort. The mean±SD birthweight (BW) z‐score was −0.59±0.74, decreasing to −1.67±0.77 at discharge. The incidence of severe PNGF increased significantly with decreasing BW and gestational age. Each 1‐unit increase in z‐score BW was associated with a 2.37‐fold increased risk for severe PNGF. Severe respiratory distress syndrome, patent ductus arteriosus, sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia were associated with severe PNGF.

Nurses’ reactions to alarms in a neonatal intensive care unit

Neonatal intensive care units (NICUs), like other intensive care units, are intended to provide immediate responses to any change in the patient’s condition. Patient-monitoring alarms and alarms from other medical equipment are very common in these units, and most alarms have no clinical significance. This study addresses the question of how alarms affect nurses’ actions by measuring the occurrence of alarms from different causes in a NICU, recording the nurses’ reactions, and analyzing the relationship between the alarms and the actions. The results show that nurses often do not respond directly to alarms, but, rather, use them as additional sources of information in their ongoing flow of actions. The probabilities for their responding to an alarm depend on the causes of the alarm, its duration, and the characteristics of the patient. These findings support the view that experienced nurses dynamically adjust their activities according to the information they receive from alarm systems and other sources, and that they combine their reactive actions with the periodic performance of routine tasks.

Maternal Hypertensive Disorders Are an Independent Risk Factor for the Development of Necrotizing Enterocolitis in Very Low Birth Weight Infants

Objective: The purpose of this study was to compare complications and outcome of preterm neonates weighing ≤1,500 g who developed necrotizing enterocolitis (NEC) to neonates without NEC. Study Design: During January, 1995 to December, 1998, 211 live preterm neonates were born with birth weight ≤1,500 g. A cross sectional prospective study was designed and two groups were defined: 17 neonates who developed NEC and 194 without NEC. Multiple logistic regression analysis was performed to determine independent risk factors for the development of NEC. Results: The prevalence of NEC was 8% (17/211). The following complications were found to be significantly higher among mothers of neonates with NEC: mild pre-eclampsia (11.8 vs. 2.6%, p = 0.04); severe pre-eclampsia (35.5 vs. 12.9%, p = 0.01); chronic hypertension (29.4 vs. 5.7%, p < 0.001) and low birth weight (968 ± 233 vs. 1,123 ± 257 g, p = 0.02). In contrast, mean maternal age, mean gestational age at delivery and parity were not significantly different between the groups. A multivariate analysis including the following factors: maternal hypertensive disorders, pregestational diabetes mellitus, birth weight and gestational age at delivery, found only maternal hypertensive disorders to be independent risk factors for NEC (OR = 5.21, 95% CI 1.64–16.58). Conclusions: Maternal hypertension is an independent risk factor for the development of NEC in preterm neonates weighing <1,500 g. Thus, maternal vascular disorders may play an important role in the pathophysiology of NEC.

Oxidative Stress in Newborn Erythrocytes

ABSTRACT: Phenylhydrazine (PHZ) exposure is used to study in vitro red cell aging mechanisms dependent on Hb oxidation. The effect of PHZ on normal neonatal red blood cells was studied in unseparated blood and after separation into light and heavy cells. PHZ caused more extensive morphologic changes in neonatal than in adult red blood cells. PHZ exposure of neonatal cells caused less reduced glutathione depletion than in adult cells. Although we found the same total amount of oxidized Hb in both cells, a well defined oxidation product of Hb was demonstrated by Mössbauer spectra only in neonatal cells. This oxidation product was not methemoglobin but a trivalent, high-spia iron compound. All neonatal cell populations were more sensitive to PHZ than were adult ones, as demonstrate by the presence of Heinz bodies at low PHZ concentration, which did not affect adult cells. These studies demonstrate greater sensitivity of neonatal cells to PHZ in all densityseparated populations.

Causes of near misses in critical care of neonates and children

Aim: The primary goal of this study was to examine the nature and causes of medical errors known as almost adverse events (AAEs) and potential adverse events (PAEs) in intensive care units.

Pseudooutbreak of Candida guilliermondii fungemia in a neonatal intensive care unit.

&NA; During a 3‐week period multiple blood cultures obtained from 14 Neonatal Intensive Care Unit infants and 3 Newborn Unit babies grew Candida guilliermondii, a yeast rarely associated with infections in humans. At the time of detection of positive cultures, most infants had been hospitalized for days or weeks for serious perinatal conditions and treated with antibiotics and intravenous hyperalimentation. Two critically ill premature infants from whom the yeast was isolated were given amphotericin B. In 7 other infants, however, yeasts were recovered on the day of birth, raising the question of pseudofungemia. Exhaustive interrogation on the blood culture practices revealed that when drawing blood for a culture from small infants, “butterfly” needles were often flushed with a diluted heparin solution to prevent blood clotting. Culture of a single lot of diluted heparin vials, prepared at the hospital pharmacy and distributed to the Neonatal Intensive Care Unit and Newborn Unit shortly before the onset of the epidemic, grew between 10 000 and 15 000 colony‐forming units of Candida guilliermondii/ml. Removal of contaminated heparin vials and discontinuation of heparinization of needles used for blood cultures resulted in cessation of the epidemic. The present outbreak illustrates the difficulties in recognizing pseudoinfections in sick premature infants and the importance of intensive investigation and intervention during such an outbreak.

Respiratory tract colonization with Ureaplasma urealyticum and bronchopulmonary dysplasia in neonates in southern Israel.

Ureaplasma urealyticum has been recognized as an important potential pathogen in premature neonates. Reported rates of colonization of the respiratory tract vary. Data on neonatal ureaplasma colonization outside the United States and Western Europe are rare. Therefore we prospectively studied nasopharyngeal and endotracheal colonization in a cohort of 114 preterm and 100 full term infants within 48 hours of birth. The colonization rate was 24% in the premature infants and zero in the full term infants. Bronchopulmonary dysplasia developed in 19% of infants with nasopharyngeal Ureaplasma colonization and in 4.6% of noncolonized infants (P < 0.03). Bronchopulmonary dysplasia developed in 40% of intubated infants with positive endotracheal Ureaplasma cultures and only in 9.8% of infants with negative endotracheal cultures (P < 0.04). Thus Ureaplasma colonization of either the nasopharynx or the trachea was associated with an increased risk for the development of bronchopulmonary dysplasia (relative risk, 4.0 and 4.1, respectively).

Classification of cries of infants with cleft-palate using parallel hidden Markov models

This paper addresses the problem of classification of infants with cleft palate. A hidden Markov model (HMM)-based cry classification algorithm is presented. A parallel HMM (PHMM) for coping with age masking, based on a maximum-likelihood decision rule, is introduced. The performance of the proposed algorithm under different model parameters and different feature sets is studied using a database of cries of infants with cleft palate (CLP). The proposed algorithm yields an average of 91% correct classification rate in a subject- and age-dependent experiment. In addition, it is shown that the PHMM significantly outperforms the HMM performance in classification of cries of CLP infants of different ages.