J.M. Quero

Multiple organ involvement in perinatal asphyxia

OBJECTIVES (1) To evaluate the frequency and spectrum of severity of multisystem dysfunction after perinatal asphyxia and (2) to analyze the relationship between the clinical and biochemical markers of perinatal asphyxia and multiorgan involvement. STUDY DESIGN Seventy-two consecutive term newborn infants with perinatal asphyxia were studied prospectively. Systematic neurologic, renal, pulmonary, cardiac, and gastrointestinal evaluations were performed. Involvement of each organ was classified as moderate or severe. RESULTS Involvement of one or more organs occurred in 82% of the infants; the central nervous system (CNS) was most frequently involved (72%). Severe CNS injury (7 infants) always occurred with involvement of other organs, although moderate CNS involvement was isolated in 14 infants. Renal involvement occurred in 42%, pulmonary in 26%, cardiac in 29%, and gastrointestinal in 29% of the infants; 15% neonates had renal failure and 19% had respiratory failure. The Apgar scores at 1 and 5 minutes were the only perinatal factors related to the number of organs involved and the severity of involvement; the Apgar score at 5 minutes had the stronger independent association. No relationship or organ dysfunction was found with the umbilical cord arterial blood pH, meconium-stained amniotic fluid, umbilical cord abnormalities, presentation, or type of delivery. CONCLUSIONS Our findings indicate that the Apgar score at 5 minutes, in infants who have other criteria for asphyxia, is the perinatal marker that may best identify infants at risk of organ dysfunction.

Dopamine Versus Epinephrine for Cardiovascular Support in Low Birth Weight Infants: Analysis of Systemic Effects and Neonatal Clinical Outcomes

BACKGROUND. Early postnatal adaptation to transitional circulation in low birth weight infants frequently is associated with low blood pressure and decreased blood flow to organs. Catecholamines have been used widely as treatment, despite remarkably little empirical evidence on the effects of vasopressor/inotropic support on circulation and on clinically important outcomes in sick newborn infants. AIMS. To explore the effectiveness of low/moderate-dose dopamine and epinephrine in the treatment of early systemic hypotension in low birth weight infants, evaluate the frequency of adverse drug effects, and examine neonatal clinical outcomes of patients in relation to treatment. DESIGN/METHODS. Newborns of <1501-g birth weight or <32 weeks of gestational age, with a mean blood pressure lower than gestational age in the first 24 hours of life, were assigned randomly to receive dopamine (2.5, 5, 7.5, and 10 μg/kg per minute; n = 28) or epinephrine (0.125, 0.250, 0.375, and 0.5 μg/kg per minute; n = 32) at doses that were increased stepwise every 20 minutes until optimal mean blood pressure was attained and maintained (responders). If this treatment was unsuccessful (nonresponders), sequential rescue therapy was started, consisting first of the addition of the second study drug and then hydrocortisone. OUTCOME MEASURES. These included: (1) short-term changes (first 96 hours, only responders) in heart rate, mean blood pressure, acid-base status, lactate, glycemia, urine output, and fluid-carbohydrate debit; and (2) medium-term morbidity, enteral nutrition tolerance, gastrointestinal complications, severity of lung disease, patent ductus arteriosus, cerebral ultrasound diagnoses, retinopathy of prematurity, and mortality. RESULTS. Patients enrolled in this trial did not differ in birth weight or gestational age (1008 ± 286 g and 28.3 ± 2.3 weeks in the dopamine group; 944 ± 281 g and 27.7 ± 2.4 weeks in the epinephrine group). Other main antenatal variables were also comparable. However, responders and nonresponders differed significantly with respect to the need for cardiorespiratory resuscitation at birth (3% vs 23%), Critical Risk Index for Babies score (3.8 ± 3 vs 7 ± 5), and premature rupture of membranes >24 hours (39.5% vs 13.6%), respectively. No differences were found in the rate of treatment failure (dopamine: 36%; epinephrine: 37%) or need for rescue therapy according to treatment allocation. Groups did not differ in age at initiation of therapy (dopamine: 5.3 ± 3.9 hours; epinephrine: 5.2 ± 3.3 hours), but withdrawal was significantly later in the dopamine group. For short-term changes, mean blood pressure showed a significant increase from baseline throughout the first 96 hours with no differences between groups. However, epinephrine produced a greater increase in heart rate than dopamine. After treatment began, epinephrine patients showed higher plasma lactate (first 36 hours) and lower bicarbonate and base excess (first 6 hours) and received more bicarbonate. Patients in the epinephrine group also had higher glycemia (first 24 hours) and needed insulin therapy more often. Groups did not differ in urine output or fluid-carbohydrate supply during the first 96 hours. For medium-term morbidity, there were no differences in neonatal clinical outcomes in responders. However, significant differences were found in the incidence of patent ductus arteriosus, bronchopulmonary dysplasia, need for high-frequency ventilation, occurrence of necrotizing enterocolitis, and death between responders and nonresponders. CONCLUSIONS. Low/moderate-dose epinephrine is as effective as low/moderate-dose dopamine for the treatment of hypotension in low birth weight infants, although it is associated with more transitory adverse effects.

Early Systemic Hypotension and Vasopressor Support in Low Birth Weight Infants: Impact on Neurodevelopment

BACKGROUND. The duration and severity of systemic hypotension have been related with altered neurodevelopment. Cerebral circulation is pressure-passive in low birth weight infants with early systemic hypotension who receive cardiovascular support. The treatment of early systemic hypotension is controversial, because it has been associated with short-term and long-term morbidity in retrospective studies. However, there has been no prospective information on cardiovascular support for hypotension and morbidity. OBJECTIVE. Our goal for this prospective study was to evaluate the effect on neurodevelopment resulting from the use of vasopressors/inotropes for early systemic hypotension. METHODS. Low birth weight infants with early systemic hypotension (<24 hours of life; study group) were assigned randomly to receive dopamine (2.5–10 μg/kg per minute) or epinephrine (0.125–0.5 μg/kg per minute) in progressively larger doses until target blood pressure was attained (treatment-success subgroup). Hemodynamically stable patients who did not receive cardiovascular support were the control group. Outcome measures were serial cranial ultrasound up to 40 weeks, structured neurologic evaluation (every 3 months), and neurodevelopmental test at 2 to 3 years of age. RESULTS. One hundred thirty patients were included (study = 60; treatment success = 38; controls = 70). Study-group patients had lower birth weight, gestational age, and 5-minute Apgar score, higher rates of premature rupture of membranes, need for cardiorespiratory resuscitation at birth, and sickness shortly after birth than the control group. The patients in the study group also had significantly higher serum troponin I levels at birth. Initial cranial ultrasound findings did not differ between groups, but the final cranial ultrasounds revealed higher rates of severe periventricular hemorrhage in the study group and higher rates of normal cranial ultrasounds in the control group. Only the latter remained when the treatment-success subgroup and control group were compared. Multivariate analysis did not detect any association between final cranial ultrasounds and the use of vasopressors/inotropes. Sixteen infants died and 103 were followed up (90% survival rate). No differences between groups were found in the rates of abnormal neurologic status, developmental delay, or combined adverse outcome (death or cerebral palsy or severe neurodevelopmental delay). CONCLUSIONS. Cautious use of cardiovascular support to treat early systemic hypotension in low birth weight infants seems to be safe. The question of whether raising systemic blood pressure to within a normal range will improve outcome should be examined by using appropriate study designs.

Fully parallel stochastic computation architecture

A space-efficient fully parallel stochastic computation architecture is described. It circumvents the main drawback of stochastic computation architectures that have been used up to now: the absence of a space-efficient technique of adding weighted input signals in parallel.

Analog to digital and digital to analog conversion based on stochastic logic

Digital to analog and analog to digital conversions can be realized in VLSI integrated circuits using a strictly digital technology and some additional analog circuits outside the IC. These techniques are based on the generation of a pulse sequence that represents a digital number. The mean value of this pulse sequence is obtained at the output of a low-pass external filter. The authors propose the use a stochastic pulse sequence instead of a traditional PWM signal. This technique has important advantages. Stochastic pulse sequences can be mathematically processed by extremely simple circuits. The product and addition of stochastic pulses can be evaluated by AND gates. The spectral properties of stochastic pulse sequences lead to less restrictive conditions to be imposed to the filter that makes the analog conversion of the pulse sequence. The authors have used this technique to implement digital to analog and analog to digital conversion in an integrated circuit that is currently being designed for a Spanish company.

A Miniaturized Two Axis Sun Sensor for Attitude Control of Nano-Satellites

This paper describes the design, fabrication, characterization, and satellite integration of a miniaturized two axis sun sensor which has been used in the attitude control system of the Spanish nano-satellite NANOSAT-1B. This device is made of four silicon photodiodes monolithically integrated in a crystalline silicon substrate, protected by a transparent cover glass assembled on the same silicon die against space radiation damage. The sensor fabrication combines standard silicon processing technology with a high performance solar cell fabrication process. The sensor, including electronics and mechanical and electrical interfacing with the satellite, has a small size (3 cm × 3 cm) and low weight (24 gr.), with a sun field-of-view greater than ±60° with an angle accuracy better than 0.15°. Three of these sensors have already been integrated in the NANOSAT-1B platform that has been successfully launched in July 2009.

Reconfigurable distributed network control system for industrial plant automation

Use of advanced communication technologies, highly integrated control, and programming platforms drastically increases the performance of industrial control systems. That is the case of Motronic, where the synergistic collaboration between industry and academia has led to an advanced distributed network control system. To be commercially successful, it needs to have a low cost and to be robust, even if this requirement implies that it is a custom design and not based on previously existing commercial solutions. Use of standards and off-the-shelf products lower development costs, but usually raise production costs. In this paper, we show that, in certain applications, design of a new system from scratch is more advantageous. This system comprises a set of dynamically reconfigurable local controller nodes, a graphical programming environment, a remote supervision and control system, and a fault-tolerant fiber optical network. TCP/IP connectivity is provided by the use of a local gateway. Motronic is currently being applied in the integrated control of large production plants and in energy and power management industries.

Postnatal adaptation of brain circulation in preterm infants.

Global and regional postnatal cerebral circulatory changes in stable preterm infants were studied, and their relation to brain injury was assessed. Thirty-five preterm infants were studied on the first and second days of age. Cerebral blood flow (CBF) (mL/hg per min) and cerebral blood volume (CBV) (mL/hg) were measured using near-infrared spectroscopy. The cerebral blood flow velocity (cm/second) (peak systolic, diastolic flow, mean flow) and resistance index (RI) were determined in the internal carotid, anterior cerebral, and striate arteries by color Doppler flow imaging. Serial cerebral ultrasound studies were performed to detect changes in brain parenchymal echogenicity or intraventricular hemorrhage (IVH); the maximum severity of these findings was considered. CBF and cerebral blood flow velocity increased significantly with time, and such changes were independent of mean blood pressure, PO(2), PCO(2), hematocrit, or glycemia. In contrast, CBV and RI remained unchanged. According to the results of sonograms, no differences were found in postnatal CBF and cerebral blood flow velocity changes, regardless of whether patients had or did not have parenchymal lesions or IVH. However, higher CBV values were found on the second day in infants with IVH compared with infants without IVH. Early coupling of CBF and metabolic demands is independent of blood pressure. Improved venous return, instead of vasodilation, could be important in this adaptation.

Stochastic pulse coded arithmetic

Among the different pulse codification techniques, stochastic pulse codification has its own arithmetic based on the similarity between Boolean algebra and statistical algebra. Summation and multiplication are the two basic arithmetic operations treated in depth in the literature. In this paper we present two digital stochastic circuits that extend traditional stochastic algebra: a division circuit and a square-root circuit, and the interfaces between the analog and stochastic domain. As a result, we are able to process analog input signals with a simple and complete processing system. These circuits can be implemented in low-cost and low-power digital programmable devices.

Neural network for constrained predictive control

Presents the way in which optimization neural nets can be used to implement generalized predictive control for systems with constrained inputs and outputs. A set of recursive formulas to obtain the net parameters from the process parameters for first-order systems is given. The results obtained by simulation and electronic implementation of the neural net are presented. >