HELEN, a Modular Framework for Representing and Implementing Clinical Practice Guidelines

Objectives: In order to implement clinical practice guidelines for the Department of Neonatology of the Heidelberg University Medical Center we developed a modular framework consisting of tools for authoring, browsing and executing encoded clinical practice guidelines (CPGs).

Methods: Based upon a comprehensive analysis of literature, we set up requirements for guideline representation systems. Additionally, we analyzed further aspects such as the critical appraisal and known bridges and barriers for implementing CPGs. Thereafter we went through an evolutionary spiral model to develop a comprehensive ontology. Within this model each cycle focuses on a certain topic of management and implementation of CPGs.

Results: In order to bring the resulting ontology into practice we developed a framework consisting of a tool for authoring, a server for web-based browsing, and an engine for the execution of certain elements of CPGs. Based upon this framework we encoded and implemented several CPGs in varying medical domains.

Conclusions: This paper shall present a practical framework for both authors and implementers of CPGs. We have shown the fruitful combination of different knowledge representations such as narrative text and algorithm for implementing CPGs. Finally, we introduced a possible approach for the explicit adaptation of CPGs in order to provide institution-specific recommendations and to support sharing with other medical institutions.

Gamma-Hydroxybutyric Acid Sedation in Neonates and Children Undergoing MR Imaging

BACKGROUND

Insufficient sedation in pediatric magnetic resonance imaging (MRI) results in prolonged examination time. To describe the efficacy and side effects of sedation with Phenobarbital short-time infusion followed by continuous gamma-hydroxybutyric acid (GHB) infusion in neonates and children for MRI examinations in a retrospective study.

PATIENTS

With Institutional Review Board approval 94 children (Group I: 1-4 weeks; Group II: >1 to 6 months; Group III: >6 months) were sedated with phenobarbital 10 mg/kg (maximum 200 mg) intravenously 30 min prior to examination. Than intravenous sedation was maintained with GHB 10 mg/kg/h after a priming dose of 30 mg/kg in 20 min.

RESULTS

In group 1 all neonates (n=8) were well sedated without side effect. One of 21 infants in group 2 showed restlessness and the MRI failed. Two of 65 patients of group 3 were not sufficiently sedated and one of them vomited.

CONCLUSIONS

Non-invasive diagnostic procedures in neonates and children may be managed by phenobarbital and GHB sedation with side effects or failure of 3%.

Conservative treatment of infantile hypertrophic pyloric stenosis with intravenous atropine sulfate does not replace pyloromyotomy

Pyloromyotomy as described by Weber and Ramstedt has been the standard therapy for infantile hypertrophic pyloric stenosis since the 1960's and conservative therapy has been abandoned. The objective of this study was to test the effectiveness of systemic atropine applied intravenously for 7 days as a conservative therapeutic strategy and as an alternative to primary operation. Forty-two consecutive term infants with infantile hypertrophic pyloric stenosis were enrolled in the study over a period of 5 years. After confirmation of the diagnosis they all received intravenous atropine at a dose of 0.04 mg/(kg day) and increased by 0.01 mg/(kg day) up to 0.12 mg/(kg day), given as 6-8 single doses per/day. Nine pairs of parents requested that their child should be operated before completing the 7 days of medical therapy. Surgery was necessary in 8 of the remaining 33 infants (24,.2%) who did not improve after 7 days of conservative treatment. Successful treatment with i.v. atropine sulfate was achieved only in 25/33 term infants at an average maximal dose of 0.11 mg/(kg day), without any major side effects. Intravenous atropine sulfate has been considered as a potential alternative therapeutic strategy in the treatment of infantile hypertrophic pyloric stenosis. Clinical improvement however was often not seen before the 6th or 7th day of intravenous treatment. A success rate for the conservative approach of only 75% at day 7 in our study does not favour atropine therapy, in view of success rates above 95% with surgical repair.

[Mortality and morbidity of very premature infants in Baden-Württemberg depending on hospital size. Is the current degree of regionalization adequate?]

BACKGROUND

Regionalization of perinatal and neonatal care improves outcome. The aim of this study was to compare outcome in preterm infants with a gestational age (GA) < 32 weeks in relation to patient volume.

METHODS

Outcome data from the state-wide neonatal quality assurance system from 2003 - 2004 from all infants treated in one of the five largest perinatal centers in Baden-Wuerttemberg were subtracted from the total dataset. Data derived from these five centers was compared with data from all other remaining NICU's in the state.

RESULTS

Mortality was 33.3 % vs. 15.0 % (other NICU's vs. five perinatal centers; p < 0.001) for infants < 26 weeks GA, 11.4 % vs. 8.9 % (n. s.) for infants 26 - 27 weeks GA, and 2.5 % vs. 3.5 % (n. s.) for infants 28 - 31 weeks GA. When analyzed as one group of infants < 28 weeks GA, mortality was 20.1 vs. 12.1 % (p = 0.003). The rate of intraventricular hemorrhage degrees III-IV was 30.2 % vs. 18.6 % (p = 0.015) for infants < 26 weeks GA, 14.5 % vs. 10.2 % (n. s.) for infants 26 - 27 weeks GA, and 2.9 % vs. 2.5 % (n. s.) for infants 28 - 31 weeks GA. The rate of periventricular leukomalacia was 11.3 % vs. 6.7 % (p = 0.18) for infants < 26 weeks GA, 6.1 % vs. 2.8 % (n. s.) for infants 26 - 27 weeks GA, and 2.8 % vs. 2.3 %; (n. s.) for infants 28 - 31 weeks GA.

CONCLUSION

This study supports the hypothesis, that regionalization of neonatal care for very immature infants to few perinatal centers with a large case load may improve survival of these infants, and may reduce morbidity, associated with long-term sequelae.

Treatment of an aneurysmal dilatation of the ductus arteriosus with indomethacin in a premature infant

A large ductus arteriosus aneurysm can lead to potentially serious and life-threatening complications. We report a case of aneurysmal dilatation of the ductus arteriosus in a premature infant that was successfully treated with indomethacin. Thus, surgical intervention with general anesthesia could be avoided.

Effects of a divided high loading dose of caffeine on circulatory variables in preterm infants

BACKGROUND

A single high loading dose of 25 mg/kg caffeine has been shown to be effective for the prevention of apnoea, but may result in considerable reductions in blood flow velocity (BFV) in cerebral and intestinal arteries.

OBJECTIVE

To assess the effects of two loading doses of 12.5 mg/kg caffeine given four hours apart on BFV in cerebral and intestinal arteries, left ventricular output (LVO), and plasma caffeine concentrations in preterm infants.

DESIGN

Sixteen preterm neonates of <34 weeks gestation were investigated one hour after the first oral dose and one, two, and 20 hours after the second dose by Doppler sonography.

RESULTS

The mean (SD) plasma caffeine concentrations were 31 (7) and 29 (7) mg/l at two and 20 hours respectively after the second dose. One hour after the first dose, none of the circulatory variables had changed significantly. One hour after the second caffeine dose, mean BFV in the internal carotid artery and anterior cerebral artery showed significant reductions of 17% and 19% (p = 0.01 and p = 0.003 respectively). BFV in the coeliac artery and superior mesenteric artery, LVO, PCO2, and respiratory rate had not changed significantly. Total vascular resistance, calculated as the ratio of mean blood pressure to LVO, had increased significantly one and two hours after the second dose (p = 0.049 and p = 0.023 respectively).

CONCLUSION

A divided high loading dose of 25 mg/kg caffeine given four hours apart had decreased BFV in cerebral arteries after the second dose, whereas BFV in intestinal arteries and LVO were not affected.

Deformability of passive and activated neutrophils in children with Gram-negative septicemia

Animal experiments suggest that obstruction of small vessels by polymorphonuclear neutrophils (PMNs) may contribute to the disturbed microcirculation in septic shock. The purpose of this investigation was to study deformability and volume of passive and activated PMNs and immature neutrophils in 15 children with Gram-negative septicemia and in 20 healthy children. Membrane cytoplasm tongues of neutrophils were aspirated by means of a micropipette system into 2.5-microm (diameter) pipettes for 60 s. Tongue growth was used as an indicator of deformability and the cell volume was calculated from the cell circumference before aspiration. Septicemic children showed higher percentages of immature neutrophils (38+/-13%) and activated PMN (12+/-5%) than healthy children (3+/-2% and 3+/-2%). In septicemic children, cellular volume of passive neutrophils decreased progressively with increasing maturity from myeloblasts (493+/-105 fL) to mature PMNs (346+/-29 fL) and the final tongue length in the micropipette increased from 2.7+/-1.1 to 8.5+/-1.8 microm during maturation. The final tongue length of activated PMNs was decreased by 60% compared with that of passive PMNs. The increased number of rigid activated and immature neutrophils may contribute to impaired microcirculation in septicemic patients.

Introducing DoT-U2--an XML-based knowledge supported checklist software for documentation of a newborn clinical screening examination

In a project concerning the German newborn screening examination "U2" we developed a software system called DoT-U2 for concurrent documentation at the point of care. Physicians can enter findings in(to) a tree structured protocol with management of logical dependencies. Additionally, all findings except free text annotations can be entered by speech recognition. The software system program is written in Java and uses separate XML-based modules both for knowledge and language representation. It can, therefore, easily be adapted to other languages and further documentation scenarios. We showed the high flexibility of the software system by integrating it in a completely new setting in Salt Lake City without major problems. We found that modular software development with platform independent Java and XML leads to highly flexible software which can be adapted to very different scenarios without knowing their requirements ahead of time.

Giving them a good start: informatics support of newborn screening and clinical care

Newborns are a vulnerable population: Exposed to dramatically changing environmental conditions, potentially suffering from impairments that cannot realistically be diagnosed during pregnancy, with the risk that unfavorable conditions escalate fast. We have investigated informatics methods and tools to make screening for congenital diseases and containment of critical processes that start in the first days safer and more efficient. This poster present a set of three different methodological approaches that all aim at comprehensive improvement of neonatal care.

Effect of activators and the phosphodiesterase inhibitors pentoxifylline and enoximone on the deformability of neutrophils in neonates and adults

BACKGROUND

Stimulated polymorphonuclear leukocytes (PMN) are extremely rigid compared to resting PMN. They may obstruct narrow vessels and contribute to ischaemic organ injury. Deformability is a prerequisite for both active and passive movement in the microcirculation.

AIM

The investigation was designed to study whether stimulators and inhibitors of stimulation show different effects on deformability of neonatal and adult PMN.

METHODS

Deformability of PMN was assessed by complete aspiration of a PMN into a micropipette with an internal diameter of 5 microm. Blood samples from 20 neonates and 20 adults were studied before and after stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP), interleukin-8 (IL-8) or tumour necrosis factor-alpha (TNF-alpha). Moreover, effects of the phosphodiesterase inhibitors Pentoxifylline (PTX) and Enoximone on the deformability of stimulated PMN were investigated.

RESULTS

fMLP, IL-8 and TNF-alpha significantly delayed aspiration times of PMN in relation to the concentrations of the stimulators. The addition of PTX or Enoximone to stimulated PMN increased the deformability up to 60% depending on the concentration of the inhibitors. No significant differences in the aspiration times were found between neonatal and adult PMN at any of the experimental conditions after activation with the three stimulators and treatment with the two inhibitors.

CONCLUSION

Neonatal and adult PMN show similar reduction of passive deformability when stimulated with either fMLP, IL-8 or TNF-alpha compared to resting PMN and a similar improvement of deformability in response to PTX or Enoximone.

Effects of intralipid infusion on blood viscosity and other haemorheological parameters in neonates and children

AIM

To study acute haemorheological effects of intralipid in preterm and full-term neonates and children. Circulatory complications of intralipid infusion, such as increases in pulmonary and peripheral flow resistance, have been associated with impaired blood rheology.

METHODS

During total parenteral nutrition, 10 preterm infants, 10 full-term neonates and 10 children received an initial dose of intralipid as continuous infusion (0.6 g/kg) over 4 h. Additionally, blood of 10 healthy preterm infants, 10 full-term neonates and 10 adults was incubated with intralipid. Whole blood and plasma viscosity (capillary viscometer), red blood cell (RBC) deformability (rheoscope) and RBC aggregation (Myrenne aggregometer) were measured before and after intralipid infusion and before and after in vitro incubation of blood with intralipid.

RESULTS

During intralipid infusion, plasma triglyceride levels increased from 0.13 +/- 0.27 to 2.16 +/- 0.68 g/l in the preterm infants, from 0.14 +/- 0.21 to 1.64 +/- 0.54 g/l in the full-term neonates and from 0.65 +/- 0.31 to 2.26 +/- 0.60 g/l in the children. Whole blood viscosity decreased by about 10% after intralipid in all three groups due to similar decreases in haematocrit. RBC aggregation decreased by about 20% after intralipid infusion. Plasma proteins, plasma viscosity and RBC deformation were not affected by intralipid. In vitro incubation of blood with intralipid resulted in a marked reduction of RBC aggregation that was related to the intralipid concentration. At intralipid concentrations of 4 and 8 mg/ml, no RBC aggregation was noted in preterm and full-term neonates. In adults, RBC aggregation decreased by 50%.

CONCLUSIONS

Previously described deleterious effects of intralipid on circulation can not be explained by changes in haemorheological properties.

Formation and relaxation of erythrocyte membrane tethers in micropipettes

The red blood cell (RBC) membrane forms tethers in response to shear forces acting on tiny membrane points. Tether formation depends on viscous and elastic membrane properties and has been used as indicator of membrane fragility. A micropipette technique was used to study time dependent tether formation and tether relaxation of individual RBC. Point attached RBC were aspirated at a negative pressure of -5 mm H2O into a micropipette with an internal diameter of 7.8 microm. If tether formation occurred and the tether reached a length of approximately 16 microm, the pipette was carefully pulled back. The RBC left the orifice of the micropipette and the tether relaxed and pulled the main body of the RBC back to the attachment point. The relaxation of the tethers was exponential. The time constant for tether relaxation was 0.144 s which is similar to the time constant for recovery of entire RBC from extensional elastic deformation. Repeated tether formation and relaxation of the same RBC led to an earlier begin of tether formation and changed the behavior of tether growth, although the relaxation time did not change. We conclude that repeated tether formation decreases the resistance of the RBC membrane to form tethers upon given shear forces. Weakening of the membrane due to repeated plastic deformation may play a role in the membrane loss of circulating RBC during aging.

HELEN, a modular framework for representing and implementing clinical practice guidelines

OBJECTIVES

In order to implement clinical practice guidelines for the Department of Neonatology of the Heidelberg University Medical Center we developed a modular framework consisting of tools for authoring, browsing and executing encoded clinical practice guidelines (CPGs).

METHODS

Based upon a comprehensive analysis of literature, we set up requirements for guideline representation systems. Additionally, we analyzed further aspects such as the critical appraisal and known bridges and barriers for implementing CPGs. Thereafter we went through an evolutionary spiral model to develop a comprehensive ontology. Within this model each cycle focuses on a certain topic of management and implementation of CPGs.

RESULTS

In order to bring the resulting ontology into practice we developed a framework consisting of a tool for authoring, a server for web-based browsing, and an engine for the execution of certain elements of CPGs. Based upon this framework we encoded and implemented several CPGs in varying medical domains.

CONCLUSIONS

This paper shall present a practical framework for both authors and implementers of CPGs. We have shown the fruitful combination of different knowledge representations such as narrative text and algorithm for implementing CPGs. Finally, we introduced a possible approach for the explicit adaptation of CPGs in order to provide institution-specific recommendations and to support sharing with other medical institutions.

Vaginal delivery and neonatal outcome in extremely-low-birth-weight infants below 26 weeks of gestational age

Outcomes of extremely-low-birth-weight infants (ELBW) with gestational age below 26 weeks based on mode of delivery (vaginal versus cesarean delivery) were retrospectively compared. During the observation period (1997 to 2000) 48 ELBW infants, below 26 weeks of gestational age, had been admitted to the Neonatal Intensive Care Unit (NICU) of the Department of Pediatrics, University of Freiburg, Germany. Twenty-seven (56%) patients were born vaginally and 21 (44%) by cesarean section. Birth weight, umbilical artery pH, and rectal temperature were significantly lower in the cesarean than in the vaginal group. Clinical Risk Index for Babies (CRIB) score showed significantly (p < 0.005) higher values in the cesarean group compared with the vaginal group. Hypothermia (rectal temperature below 36.2 degrees C after birth) was more common in the cesarean group (48%) than in the vaginal group (33%). Eighty-five percent of the fetuses in the vaginal group received antenatal corticosteroids and 88% in the cesarean group. Survival rate was significantly (p < 0.05) higher in infants born vaginally (78%) than in the cesarean group (43%). Several complications occurred less frequently after vaginal birth than after cesarean section: intraventricular hemorrhage grade III to IV (18 versus 33%); periventricular leukomalacia (4 versus 14%); and neonatal septicemia (33 versus 52%), but not statistical significant. In our study group, extremely immature preterm infants had a more favorable outcome if they were born vaginally when compared with infants delivered by cesarean section.

Human placental trophoblast cells express alpha-tocopherol transfer protein

Alpha-tocopherol transfer protein (alpha-TTP), a 30 kDa cytosolic protein first described to be present in the liver and important for alpha-tocopherol trafficking, plays a major role in maintaining alpha-tocopherol levels in plasma, while alpha-tocopherol is known as the major lipid-soluble antioxidant. Expression of alpha-TTP has not only been described in animal model liver, but also in diverse other tissues such as rat brain or pregnant mouse uterus, the latter finding stressing the importance of alpha-TTP for embryogenesis and foetal development. In this study, we report the identification of alpha-TTP in human liver by anti-human alpha-TTP monoclonal antibodies made in rat and the cellular localization of alpha-TTP in term human placenta. By immunohistochemistry, intense staining of alpha-TTP was seen in syncytiotrophoblast as well as in villous and invading extravillous cytotrophoblast, while basal decidual cells showed slighter, but present staining of alpha-TTP. Foetal vessel endothelium remained unstained. It is therefore suggested that alpha-TTP may play a major role in supplying alpha-tocopherol to the foetus prior to delivery and is likely involved in maintaining adequate alpha-tocopherol levels in the foetus.

Alpha-tocopherol transfer protein is specifically localized at the implantation site of pregnant mouse uterus

Alpha-tocopherol transfer protein (alpha-TTP) was first described to play a major role in maintaining alpha-tocopherol levels in plasma, while alpha-tocopherol was primarily reported to be a factor relevant for reproduction. Expression of alpha-TTP is not only seen in the liver, from where it was first isolated, but also in mouse uterus, depending on its state of pregnancy, stressing the importance of alpha-TTP for embryogenesis and fetal development. The cellular localization of alpha-TTP in mouse uterus is reported here. By immunohistochemistry, alpha-TTP could be localized in the secretory columnar epithelial cells of the pregnant uterus on Days 4.5 and 6.5 postcoitum as well as in the glandular epithelial cells and the inner decidual reaction zone surrounding the implantation site. On Days 8.5 and 10.5 postcoitum (midterm of mouse pregnancy), alpha-TTP could still be detected in the uterine secretory columnar epithelial cells, while in alpha-TTP knockout mice, no immunostaining was visible. It is suggested that alpha-TTP plays a major role in supplying the placenta and consecutively the fetus with alpha-tocopherol throughout pregnancy. We conclude that alpha-tocopherol plays a role in the process of implantation and that alpha-TTP may be necessary for adequate alpha-tocopherol status of the fetus.

Hepatic failure with neonatal tissue siderosis of hemochromatotic type in an infant presenting with meconium ileus. Case report and differential diagnosis of the perinatal iron storage disorders

We report on a female preterm infant with hepatic failure and neonatal tissue siderosis of hemochromatotic type diagnosed by using both histochemistry and atomic absorption spectroscopy. The infant presented with meconium ileus, signs of rapidly progressive hepatic failure, and hyperferritinemia (7132 ng/ml). Despite surgery and intensive care the infant died 32 days after birth. Postmortem examination showed a wrinkled liver with extensive collapse of the hepatic architecture and regenerating nodules as well as hepatic and extrahepatic iron accumulation of hemochromatotic type, sparing the reticuloendothelial system. Atomic absorption spectroscopy confirmed an increase in the iron content of various organs: liver, heart, pancreas, oral salivary gland, kidney, and adrenal gland. The increase in the iron content of various organs was determined by comparing the analysis of the propositus with those of 5 gestationally age-related preterm infants who had died in the intensive care unit: 2 died of meconium aspiration syndrome, the other 3 of hyaline membrane disease, bronchopulmonary dysplasia, and immaturity, respectively. We also compared the analysis of 15 fetuses having a a condition predisposing to iron accumulation (trisomy 21, trisomy 18, cytomegalovirus, amnion infection syndrome, Rhesus- and ABO-incompatibility, congenital hemolysis, anti-phospholipid syndrome, congenital heart disease). Delta F508, the most frequent mutation seen in cystic fibrosis patients, was excluded by gene sequencing. Different noxae causing iron accumulation in the neonatal period have led to the statement that neonatal hemochromatosis may collect different etiologies, such as metabolic disorders, infections, chromosomal aberrations, and immunological disorders. In this study, we report the singular evidence of neonatal iron accumulation of hemochromatotic type in an infant presenting with meconium ileus and propose a classification of the neonatal disorders associated with iron accumulation.

Restrictive dermopathy: case report, subject review with Kaplan-Meier analysis, and differential diagnosis of the lethal congenital contractural syndromes

We report on a 34-week-old infant with restrictive dermopathy (RD), a rare lethal genodermatosis, characterized by an abnormal skin growth and differentiation with thin, tightly adherent skin that causes a dysmorphic face, generalized flexion joint contractures, and respiratory insufficiency. Kaplan-Meier analysis of 32 previously well-described infants affected with RD showed a median survival of 132 hours. Lethal congenital contractural syndromes, including Pena-Shokeir phenotype, cerebro-oculo facio-skeletal syndrome, and lethal multiple pterygium syndrome, should be considered first in the differential diagnosis. Other lethal contractural syndromes are discussed.

Effect of caffeine on oxygen consumption and metabolic rate in very low birth weight infants with idiopathic apnea

OBJECTIVE

Methylxanthines are among the most commonly prescribed drugs in neonatal intensive care. This study evaluates the effect of caffeine on oxygen consumption and metabolic rate in premature infants with idiopathic apnea.

METHODS

Eighteen preterm infants at gestational ages from 28 to 33 weeks and birth weights of 890 to 1680 g were enrolled in the study. Nine preterm infants received caffeine therapy, and 9 served as a control group. Oxygen consumption and energy expenditure were examined before, during, and after caffeine treatment.

RESULTS

Oxygen consumption increased significantly from 7.0 +/- 0.9 before caffeine to 8.8 +/- 0.7 mL/kg/min after 48 hours of caffeine therapy, and energy expenditure increased from 2.1 +/- 0.3 to 3.0 +/- 0.2 kcal/kg/hour. During the observation period of 4 weeks of caffeine treatment, oxygen consumption increased significantly in the caffeine group compared with the control patients. In the caffeine group, a lower environmental temperature was sufficient to maintain a normal body temperature. With similar caloric intake in both groups during the study period, daily weight gain in the control group was significantly higher (21 +/- 4 vs 42 +/- 2 g/d). None of the other parameters recorded changed during caffeine therapy.

CONCLUSION

Long-term administration of caffeine in preterm infants is associated with an increase in oxygen consumption and with a reduction of weight gain. This may have implications for clinical practice as nutritional regimens need to be adjusted during this therapy.

L-selectin tyrosine phosphorylates cbl and induces association of tyrosine-phosphorylated cbl with crkl and grb2

L-Selectin-mediated rolling of leukocytes on endothelial cells is an important step for lymphocyte homing and an early event in the immune response to pathogens or inflammatory stimuli. We have previously elucidated intracellular signaling cascades upon L-selectin engagement resulting in activation of Ras, Rac and JNK as well as cytoskeletal changes, oxygen release, ceramide synthesis and receptor capping. Activation of the src-tyrosine kinase p56lck is followed by phosphorylation of the L-selectin molecule and MAP-K. Here we show a tyrosine kinase dependent phosphorylation of the Cbl adapter protein after L-selectin engagement in lymphocytes. Phosphorylation of Cbl was absent in Jurkat cells that are pharmacologically treated with tyrosine kinase inhibitors and in lck-deficient JCaM cells. There is an activation induced association of tyrosine phosphorylated Cbl with Grb2 and CrkL, respectively, but not CrkII. Therefore, the adapter protein Cbl plays a role in L-selectin signaling and might modulate immune function by the specific recruitment of signaling molecules to multiprotein complexes.

Postnatal changes in neonatal acylcarnitine profile

++Electrospray-tandem mass spectrometry represents a powerful method for detection of inborn errors of fatty acid metabolism. In the present study, it was used to examine neonatal carnitine metabolism, which reflects fatty acid metabolism. In 70 healthy neonates, blood samples were taken from the umbilical cord and by heel-stick puncture in full-term neonates on postnatal d 5. Cord blood specimens were also obtained from 15 preterm and 10 small-for-gestational-age infants. Acylcarnitine concentrations were measured in dried blood spots by electrospray tandem mass spectrometry. Compared with cord blood, the levels of nearly all acylcarnitine species were significantly higher on the postnatal d 5, whereas free carnitine remained unchanged. Total acylcarnitine/free carnitine-ratio increased, whereas the free carnitine/total carnitine-ratio (0.54 +/- 0.05; p < 0.01) further decreased. A reduced availability of free carnitine in the early neonatal period may affect fatty acid oxidation and thus be of potential pathophysiological relevance under conditions with higher energy demands, e.g. in sepsis. Cord blood concentrations of free carnitine, total carnitine, and total acylcarnitines were strongly related to birth weight (p < 0.01). Lower umbilical artery pH, i.e. mild hypoxia, caused accumulation of mainly long-chain acylcarnitines. This implicates that long-chain acylcarnitines could serve as a parameter of perinatal asphyxia.

Influence of the endothelial glycocalyx on cerebral blood flow in mice

The endothelial surface layer (glycocalyx) of cerebral capillaries may increase resistance to blood flow. This hypothesis was investigated in mice by intravenous administration of heparinase (2500 IU/kg body weight in saline), which cleaves proteoglycan junctions of the glycocalyx. Morphology was investigated by transmission electron microscopy. Cerebral perfusion velocity was recorded before and during heparinase or saline treatment using laser-Doppler flowmetry. In addition, cerebral blood flow (CBF) was measured 10 minutes after heparinase or saline treatment using the iodo[14C]antipyrine method. Laser-Doppler flowmetry and CBF measurements were performed during normocapnia and severe hypercapnia (PCO2: 120 mm Hg). After heparinase, morphology showed a reduced thickness of the glycocalyx in cortical microvessels by 43% (P < 0.05) compared with saline-treated controls. Under normocapnic conditions, a 15% (P < 0.05) transient increase of cerebral flow velocity occurred 2.5 to 5 minutes after heparinase injection. Laser-Doppler flow and CBF returned to control values ten minutes after the injection. However, during severe hypercapnia, heparinase treatment resulted in a persisting increase in laser-Doppler flow (6%, P < 0.05) and CBF (30%, P < 0.05). These observations indicate the existence of a flow resistance in cerebral capillaries exerted by the glycocalyx. The transient nature of the CBF increase during normocapnia may be explained by a vascular compensation that is exhausted during severe hypercapnia.

[Acute retinpathia praematurorum. Is plasma prorenin level of prognostic value?]

BACKGROUND

In patients with diabetes mellitus an elevated level of plasma prorenin (PP) may be associated with proliferative diabetic retinopathy. Although retinopathy of prematurity (ROP) is also characterized by retinal vasoproliferation, no study on PP in ROP appears to have been carried out. This study investigated PP prospectively in preterm infants with high risk of ROP.

PATIENTS AND METHODS

In 304 preterm infants (gestational age 24-36 weeks, mean +/- SD 29.8 +/- 2.6 weeks; birth weight 570-1750 g, 1180 +/- 294 g) PP was examined prospectively between 3 and 14 weeks postnatally. Renin and total renin (after cryoactivation) were determined by radioimmunoassay. Total renin minus renin is the PP level; PP was correlated with the presence of ROP, stage of ROP, gestational age, birth weight, and postnatal age.

RESULTS

There was no significant difference between mean PP in 112 preterm infants with ROP (682 +/- 666 ng/l) and that in 192 preterm infants without ROP (622 +/- 454 ng/l). There was no correlation between PP and the stage of ROP, gestational age, or birth weight. Mean PP decreased with increasing postnatal age (postnatal age 3-4 weeks: 906 +/- 587 ng/l; 7-8 weeks: 585 +/- 423 ng/l; 13-14 weeks: 326 +/- 205 ng/l).

CONCLUSION

This study found no significant difference in PP between preterm infants with and those without ROP. Thus PP is not a valid predictor or indicator of ROP. However, the study showed a hitherto unknown correlation between PP and postnatal age in preterm infants.

Surfactant modulates intracellular signaling of the adhesion receptor L-selectin

Intraalveolar leukocyte accumulation is one of the hallmarks during respiratory distress. In the intraalveolar space, leukocyte activation is mediated by pathogens, cytokines, and different ligands binding to adhesion molecules. Leukocyte stimulation via the adhesion molecule L-selectin is specifically induced by ligands expressed on leukocytes, platelets, endothelial cells, or lipopolysaccharide. Recently, we have demonstrated that leukocyte activation by L-selectin transmits several intracellular signaling cascades resulting in capping and cytoskeletal changes, the activation of kinases and neutral sphingomyelinase, the recruitment of adaptor proteins to the cell membrane, the activation of the small G-proteins Ras and Rac, and the release of oxygen. In the present study, we examined the effects of surfactant on L-selectin-induced signal transduction in leukocytes. Using fluorescence microscopy, we provide evidence that preincubation of leukocytes with surfactant significantly inhibits receptor capping; 28+/-7% of cells show capping after L-selectin stimulation versus 8+/-5% and 3+/-1% of cells after preincubation with Exosurf and Curosurf, respectively (p < 0.05). The activity of the neutral sphingomyelinase in cell lysates is also modulated by surfactant. In addition, we show that the activation of the tyrosine kinase p56lck is diminished by approximately 50% after surfactant treatment. This results in inhibition in tyrosine phosphorylation of certain intracellular proteins. The interaction of the L-selectin molecule with its antibody was not influenced by surfactant as shown by flow cytometry. Surfactant inhibits intracellular signaling events of the L-selectin receptor in leukocytes and might therefore contribute to the modulatory effects of surfactant on immune function.

[Results of a survey on the use of guidelines in neonatology]

To assess the use of guidelines in neonatology we conducted a survey on hyperbilirubinemia in 185 German pediatric hospitals from June to September 1999. Of these 136 hospitals (73%) treating infants with hyperbilirubinemia responded. Specific standards or guidelines were used by 99% of participating hospitals. 49% of those used a hospital-based guideline, 54% the recommendations of the Gesellschaft für Neonatologie und pädiatrische Intensivmedizin, 24% another not further specified guideline. In 98% of the hospitals paper copies were used. In 21% of the hospitals the implemented guidelines were also electronically available. A coordinator for their guidelines was available in 51% of the hospitals, whereas 49% did not coordinate locally the use of their guidelines. In conclusion, guidelines should be well maintained and regularly updated in order that they do not lose their impact and significance. In addition, the potential of these concise summaries of medical expertise do not seem to be fully exploited.

Longitudinal evaluation of salivary cortisol levels in full-term and preterm neonates

The aim of the present study was to test the practicability of sequential cortisol determinations in saliva of low birth weight neonates and to evaluate the impact of systemic and inhaled glucocorticoid therapy on saliva concentrations of cortisol in preterm neonates with bronchopulmonary dysplasia (BPD). Salivary cortisol levels were measured by RIA in saliva samples from 10 full-term and 10 preterm healthy neonates and from 20 preterm neonates with BPD during systemic [dexamethasone (DEX); n = 10] or topical steroid therapy [budesonide (BUD); n = 10]. Saliva samples of each individual were collected on 3 consecutive days at 06.00, 12. 00, 18.00 and 24.00 h. Cortisol levels in saliva ranged from 0.8 to 60.6 nmol/l (median 6.5 nmol/l) in full-term neonates, from 0.6 to 52.1 nmol/l (median 5.5 nmol/l) in preterm neonates, from 0.4 to 14. 0 nmol/l (median 1.0 nmol/l) in preterm neonates treated with DEX and from 0.4 to 15.2 nmol/l (median 2.5 nmol/l) in preterm neonates treated with BUD. Autocorrelation analysis revealed a distinct endogenous cortisol rhythm in 2 of the 10 healthy full-term neonates and in 3 of the 10 healthy preterm neonates with a wavelength of 12-30 h. Salivary cortisol levels in preterm neonates treated with DEX or BUD were significantly lower than those measured in healthy preterm neonates. These results demonstrate that the measurement of salivary cortisol levels is a reliable and practicable way of assessing adrenal function in full-term and preterm neonates. This study also shows for the first time that some neonates display an endogenous cortisol rhythm which is not coupled to the exogenous day/night cycle. Furthermore, systemic and nebulized glucocorticoids suppress adrenal function in low-birth-weight neonates. After treatment these children should be closely monitored for potential adrenal insufficiency.

Decrease of cholestasis under "continuous extracorporeal stool transport (CEST)" in prematures and neonates with stomas

According to recent studies, the percentage of neonates suffering a combination of very low birth weight (VLBW) and intestinal malformation or diseases that require surgery has increased. As opposed to mature newborn, split stoma is the therapy of choice in VLBW infants. These neonates and patients with other causes for a congenital or acquired short-bowel syndrome usually require parenteral nutrition and have a high risk of a cholestasis. Until 1993, stoma patients were treated with a special diet in our department, but depending of the stoma site often required parenteral nutrition, while the non-used distal bowel was irrigated with an isotonic electrolyte solution. With this regime, up to 38.5% of the treated patients (10126) were found to have a hyperbilirubinemia (> 3 mg/dl) after the 21st day of life. 1994, we started to use a device that continuously transfers the intestinal chylus from the proximal into the aboral bowel via a pump like a continuous extracorporeal stool transport (CEST). In this study, we evaluated the risk of cholestasis by comparison of the prospectively investigated group (CEST-group 1994-1998) of 33 infants with the results of the retrospectively studied group of 26 patients operated on between 1987 and 1993. We found a significantly lower risk of cholestasis in the CEST-Group (12.9% versus 38.5%; p<0.04). Only 3% of our patients with CEST (one patient) required permanent parenteral nutrition, compared to 50% of the conventionally treated patients.

Risk factors in retinopathy of prematurity. a multivariate statistical analysis

OBJECTIVE

To analyze risk factors in retinopathy of prematurity (ROP).

PATIENTS AND METHODS

Four hundred forty-seven surviving very-low-birth-weight infants (birth weight </=1,500 g) were enrolled in a retrospective study. Clinical data underwent multivariate analysis using stepwise logistic forward regression.

RESULTS

For 402 of the babies a complete dataset of 38 possible risk factors was available. Multivariate analysis showed 10 factors to be independently significant variables. Low birth weight, low gestational age, artificial ventilation for more than 7 days, high volume of blood transfusion and surfactant therapy were risk factors associated with higher rates of ROP. Necrotizing enterocolitis, maternal pre-eclampsia, lung maturation by antepartum betamethasone application, vitamin E and phototherapy were accompanied by a lower incidence of ROP.

CONCLUSIONS

This study confirms several risk factors recognized by previous statistical analysis. In addition, this study reveals maternal pre-eclampsia, which is associated with chronic intrauterine stress, as a statistically independent factor and as having an influence on the incidence of ROP.