Search PubMed⌕ Search

Biomedical subjects

H N Lafeber

Publications and source records attributed to H N Lafeber.

At least 37 records · Page 2Linked to original sources
PubMed1998

Magnetic resonance imaging of the brain in premature infants during the neonatal period. Normal phenomena and reflection of mild ultrasound abnormalities.

An MRI study was performed in 34 preterm infants who were clinically and neurologically normal and whose cranial ultrasound revealed no or only mild abnormalities. The postconceptional age at MRI varied between 30.6 and 37 weeks. The purpose of the study was to evaluate the significance of periventricular changes in signal intensity on MRI, comparing MRI with ultrasound. T1-weighted and T2-weighted images were assessed for changes in signal intensity of the periventricular white matter relative to the remainder of the cerebral hemispheric white matter. Cerebral MRIs of 13 postterm infants were additionally investigated. In all preterm infants small localized areas of high signal intensity on T1-weighted images and low signal intensity on T2-weighted images were seen adjacent to the frontal horns of the lateral ventricles. They faded with increasing age and were no longer seen one month after term in the group of postterm infants. The areas were considered normal before term age and probably represent remnants of the germinal matrix. Periventricular echodensities corresponded with a zone of changed signal intensity within the periventricular white matter on MRI. MRI signal change correlated with the presence and location of echodensities; the MRI signal changes slowly faded away after the echodensities disappeared.

Brain↗
PubMed1997

Nutritional management and growth hormone treatment of preterm infants born small for gestational age.

In severe cases of intrauterine growth retardation, elective preterm delivery may provide the possibility for nutritional intervention to prevent some of the long-term consequences of the catabolic condition in utero. Neonatal nutritional management is aimed at providing a high protein intake of up to 4 g/kg/day in order to obtain the rapid increase in protein that is seen in normally growing infants during the early postnatal period. Unfortunately, due to impaired production of urea, high plasma levels of ammonia, which may be rate limiting with respect to an optimal gain in protein, are often observed in the preterm infant born small for gestational age (SGA). In an attempt to stimulate protein synthesis in preterm infants born SGA, growth hormone (GH) treatment was given to seven such infants during the early postnatal period. The infants received daily subcutaneous injections of GH (1.0 IU/kg/day) from postnatal day 7 until a body weight of 2000 g was reached (postnatal week 7-8). A further seven preterm infants born SGA were studied as controls. GH treatment had no significant effects on growth, body composition, net protein gain and glucose metabolism. Furthermore, plasma levels of insulin-like growth factor I (IGF-1) and IGF-binding protein-3 revealed a normal developmental increase and were not significantly altered by GH treatment. These results may be explained by a relative GH insensitivity or resistance during this period of early preterm life.

Controlled Clinical Trials as Topic↗
PubMed1996

Accuracy of oscillometric blood pressure measurement in critically ill neonates with reference to the arterial pressure wave shape.

OBJECTIVE: To perform further evaluation of the oscillometric device for neonatal arterial blood pressure (ABP) measurement, using a catheter-manometer system (CMS) for accurate intraarterial measurement. We aimed to describe the influence of the radial artery wave shape on oscillometric ABP determination, as pressure wave-shape influences the relationships between systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) in the wave. These relationships are part of the algorithms contributing to the final ABP determination in the oscillometric device. DESIGN: Intra-patient comparison of two blood pressure measurement systems. SETTING: Neonatal intensive care unit. PATIENTS: In 51 critically ill newborn infants, ABP was determined oscillometrically in the brachial artery and, simultaneously, invasively in the radial artery using a high-fidelity CMS. Clinical data of the infants were: gestational age: 29 (25-41) weeks; birthweight: 1200 (500-3675) g, postnatal age: 6 (2-46) h. METHODS: Statistical analysis was performed with the paired Student's t-test. Multiple regression analysis was used to determine the influence of birthweight and height of the blood pressure on the results. MEASUREMENTS AND MAIN RESULTS: In 51 infants, 255 paired values of SAP, DAP and MAP were recorded. In all recordings, we determined the relationship between SAP, DAP and MAP, using the equation: MAP = alpha%(SAP - DAP) + DAP. For SAP, DAP, MAP and alpha, we computed mean differences (bias) and the limits of agreement (precision). Biases for SAP, DAP, MAP and alpha were significantly different from zero (P < 0.001) and the limits of agreement for SAP, DAP and MAP were wide: 18.8 mmHg, 17.2 mmHg and 15.2 mmHg respectively. The relationship between invasive and noninvasive values is only partly (7-19%) influenced by the height of the blood pressure; low values of SAP, DAP and MAP tend to give overestimated oscillometric values. In the relationship between SAP, DAP and MAP, alpha was found to be 47% invasively (as generally found in the radial artery in newborns) and 34% noninvasively (as generally found in the brachial/radial artery in adults). CONCLUSIONS: Inaccuracy of the oscillometric device may be partly explained by the incorporation of an inappropriately fixed algorithm for final ABP determination in newborns. Care should be taken when interpreting the oscillometrically derived values in critically ill newborn infants.

Adult↗
PubMed1996

Effects of recombinant human growth hormone treatment in intrauterine growth-retarded preterm newborn infant on growth, body composition and energy expenditure.

The effects of recombinant human growth hormone treatment during the early postnatal period on growth, body composition and energy expenditure were studied in seven intrauterine growth-retarded newborns. Seven infants were studied as controls. No differences were seen in bodyweight or height gain (15.9 +/- 1.5 g/kg per day and 1.02 +/- 0.24 cm/week in the treated and 16.3 +/- 1.4 g/kg per day and 1.11 +/- 0.30 cm/week in the control group). Skinfold growth rate was 0.52 +/- 0.20 mm/week in the treated vs. 0.56 +/- 0.28 mm/week in the control group. Total body water (as a percentage of bodyweight, 80 +/- 3.0% vs. 80 +/- 4.0%) and energy expenditure (67.5 +/- 7.4 vs. 66.7 +/- 6.4kcal/kg per day) using 2H2 18O showed identical results in both groups. We conclude that the recombinant human growth hormone treatment directly after birth in intrauterine growth-retarded newborn infants results neither in an increase in growth rate nor a change in body composition or energy expenditure during the early postnatal period.

Anthropometry↗
PubMed1996

Leucine and glucose kinetics during growth hormone treatment in intrauterine growth-retarded preterm infants.

The present study was performed with the objective to investigate the possible effects of recombinant human growth hormone (rhGH) supplementation on protein and glucose metabolism during the early postnatal period in seven intrauterine growth-retarded (IUGR) preterm infants. Eight infants were studied as controls. The metabolic rate was measured by indirect calorimetry, and whole body protein and glucose kinetics were measured using constant-rate infusions of [1-13C] leucine and [U-13C]glucose during continuous adequate oral feeding. Energy expenditure was similar in both groups. In the rhGH-treated group of infants, leucine turnover (470 +/- 76 vs. 409 +/- micromol/ kg/day), leucine used for protein synthesis (402 +/- 72 vs. 337 +/- 36 micromol /kg/day), and leucine derived from protein breakdown (365 +/- 71 vs. 304 +/- 41 micromol/kg/day) were increased. However, net leucine balance was not increased (37 +/- 17 vs. 34 +/- 13 micromol/kg/day). The total rate of appearance of glucose was 10.1 +/- 1.2 vs. 10.0 +/- 1.3 mg/kg/min. We suggest that immediate postnatal treatment with rhGH is not effective in stimulating protein gain and has no effect on glucose kinetics in IUGR preterm infants.

Birth Weight↗
PubMed1996

Relative kinetics of phenylalanine and leucine in low birth weight infants during nutrient administration.

The effect of the route of nutrient administration on the relative rates of leucine and phenylalanine kinetics was examined in 30 low birth weight (LBW) infants using L-[1-(13)C]leucine, L-[2H5]phenylalanine, and L-[2H2]tyrosine tracers. The infants received special premature formula (PF, n = 10, 117 +/- 8 kcal.kg-1.d-1 and 3.2 +/- 0.2 g protein.kg-1.d-1) or fortified human milk (HM, n = 10, 106 +/- 6 kcal.kg-1.d-1 and 3.0 +/- 0.2 g protein.kg-1.d-1), or parenteral nutrition (PN, n = 10, 80 +/- 25 kcal.kg-1.d-1 and 1.8 +/- 0.3 g protein.kg-1.d-1). The rate of appearance (Ra) of leucine (RaLeu), was significantly higher in group PF as compared with groups HM and PN (434 +/- 51 versus 377 +/- 33 and 359 +/- 50 mumol.kg-1.h-1, p < 0.05). The Ra of phenylalanine (RaPhe) was lower in group HM as compared with group PF (94 +/- 18 versus 115 +/- 16, p < 0.05), RaPhe in group PN (108 +/- 24 mumol.kg-1.h-1) was in between group PF and HM. The relative rate of RaPhe and RaLeu expressed as RaPhe/ RaLeu ratio was lower in all groups than that expected from reported whole body protein composition and from that reported in adults. The ratio of phenylalanine hydroxylation to leucine decarboxylation was 0.202 in group PF, 0.212 in group HM, and 0.161 in group PN, suggesting a higher rate of decarboxylation of leucine relative to hydroxylation of phenylalanine. We conclude that: 1) the higher RaLeu compared with the RaPhe may be the result of either a higher turnover of a body protein enriched in leucine or the consequence of higher leucine intake in infant nutrition and 2) whole body protein kinetics calculated from a single amino acid tracer do not adequately represent whole body protein metabolism.

Food, Fortified↗
PubMed1996

Bisferiens peaks in the radial artery pressure wave during patent ductus arteriosus in newborn infants: relationship with ascending aortic flow.

Previously, we found evidence that bisferiens peaks in the radial artery pressure wave in the newborn infant may suggest the presence of a left-to-right shunt through a patent ductus arteriosus (PDA). The purpose of the present study was to analyze the origin of this pulsus bisferiens. Starting from the assumption that the radial artery pressure wave form is similar to the aortic pressure wave form, as described previously, we attempted to explain the bisferiens peaks on the basis of echocardiographically obtained ascending aortic flow. We studied 11 preterm mechanically ventilated infants with a left-to-right shunt through a PDA and 7 without. Aortic volume flow was established echocardiographically, and radial artery blood pressure measurement was performed with a high fidelity cathetermanometer system. Ascending aortic peak flow during PDA was significantly higher in the case of PDA, compared with the case without PDA. An augmented peak flow with an abrupt decline after the high peak in PDA, resulting in a sharp pressure peak with a steep decline after the peak, was thought to explain the first sharp peak of pulsus bisferiens. An abrupt decline of flow after peak flow is thought to be due to the fast runoff of blood through the ductus. According to the pulsatile pressure dynamics theories, which state that pressure wave forms consist of forward and backward wave forms, the second peak of the pulsus bisferiens can be explained by the return of the reflected (backward) wave form when the forward wave form has already considerably decreased. We conclude that the bisferiens peaks found in PDA result from a combination of large stroke volume (augmented first peak) and large runoff (quick decline of the forward wave) before the return of the reflected wave.

Aorta↗
PubMed1995

Neonatal transport by helicopter in The Netherlands: a 7-year overview.

In the Netherlands, neonatal intensive care is provided in 10 neonatal intensive care centres. Although antenatal transport is preferred, each year more than 1000 newborns are transported to the centres, in the majority of cases by ambulance. Transport by helicopter became available in 1987. From June 1987 till December 1993, 583 infants were transported by helicopter (median gestational age 32 weeks, range 24-43). Forty-four per cent had a gestational age of less than 32 weeks. Four hundred and forty-six infants were mechanically ventilated. No baby died in transfer. After admission, 101 infants died (18.4%). There were no accidents during transport Ten per cent of the requested flights was cancelled because of weather conditions. The mean transport time of the babies was 36 min (range 10-145), and the mean transport time of the transport teams was 128 min (range 20-345). The transports carried out from 1987 to 1989 were recalculated with regard to duration and cost, assuming they were carried out by ambulance instead of by helicopter: for the babies, the mean transport time by helicopter was 75% less than the calculated mean transport time by ambulance. However, the financial costs per transport were on average Dutch florins (DFL) 3000 higher by helicopter than by ambulance. In the Netherlands, the use of a helicopter for neonatal transport reduces the transport time, but doubles the costs.

Air Ambulances↗
PubMed1995

Bisferiens peaks in the radial artery pressure wave in newborn infants: a sign of patent ductus arteriosus.

Previously, we found evidence that radial artery pressure wave forms in newborns represent central aortic wave forms, provided that pressure is measured with adequate accuracy. Therefore, we postulated that the neonatal radial artery wave form, like the adult aortic wave form, may contribute to cardiovascular diagnosis. We investigated whether radial artery wave forms in infants suffering from patent ductus arteriosus (PDA) are different from the wave forms as seen without the presence of PDA. We studied 34 newborn infants with a radial artery line and with the possible clinical diagnosis of PDA with left-to-right shunt. On the basis of echocardiographic examination to assess PDA, these infants were divided in two groups: infants with PDA (n = 24) and without PDA (n = 10). In 15 out of 24 infants with PDA, recordings were repeated after ductal closure. Blood pressure measurement was performed with a high fidelity cathetermanometer system using a tip-transducer (natural frequency 95 Hz, damping coefficient 0.15). Contour analysis was performed by describing morphology of the waves during PDA and without PDA. In 23 out of 24 infants with PDA, a pulsus bisferiens was present: two peaks separated by a deep cleft. The average pressure difference between the first pressure peak and the cleft [delta Ppeak1] was 0.35 +/- 0.19 kPa, and the average difference between the cleft and the second pressure peak [delta Ppeak2] was 0.44 +/- 0.23 kPa. the ratio of mean magnitude of delta Ppeak1 and delta Ppeak2 was 0.81 +/- 0.26. None of the 10 infants without PDA showed pulsus bisferiens.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1995

Radial artery blood pressure measurement in neonates: an accurate and convenient technique in clinical practice.

To achieve accurate blood pressure measurement through radial artery catheters in infants, we previously developed an experimental high-fidelity catheter-manometer system (CMS). As this system lacks facilities for flushing and for blood sampling, we aimed to further develop this technique in order to make the system suitable for clinical practice. In addition, we aimed to develop methods to automate processing of the pressure wave forms. The high-fidelity system to be improved consisted of a 24 Gauge catheter, a threeway stopcock and a tip-manometer. We inserted this system in the catheter-manometer system as routinely used i.e. the remaining end of the stopcock was connected to the fluid-filled CMS as used routinely. This combined system became clinically applicable, since blood samples could be obtained and flushing could be performed. The measurement chain was completed by application of a modified physiological monitor and a computerized method to analyze pressure wave forms. In this manner accurate beat-to-beat pressure parameters were obtained. This technique was applied to 25 neonates admitted for intensive care and requiring arterial access. Gestational age of these infants ranged from 25-40 (median 29) weeks and birth weight ranges from 500-3375 (median 1060) grams. In all infants the technique was found to be convenient and the high-fidelity blood pressure measurements were performed without any problems. The advantage of the present system is the potential for both correct intermittent recordings of arterial wave forms in close relation to clinical condition and for the establishment of accurate radial artery beat-to-beat pressure values in clinical practice.

Blood Pressure↗
PubMed1993

Cortical laminar abnormalities--occurrence and clinical significance.

Cortical laminar necrosis is a histopathological entity, related to conditions of cerebral energy depletion. Clinical correlates are supposed to be spastic motor deficits, decreased intellectual capacity and epilepsy. A study was performed in 45 children with cortical laminar abnormalities in signal intensity on MRI. The purpose of the study was to evaluate causes and clinical consequences of these cortical abnormalities on MRI in order to find indirect evidence for the hypothesis that they may represent cortical laminar necrosis. In view of the frequently present concomitant white matter damage, two contrast groups were formed: one group of 40 children with periventricular white matter abnormalities, part of them with subcortical extensions of the white matter damage; and another group of 53 children without abnormalities on MRI. Data concerning history, present clinical condition and final diagnosis were collected. The presence of cortical laminar abnormalities on MRI was found to be strongly associated with a history of cerebral energy depletion, especially hypoxia-ischemia, either in the perinatal period or later in life. Whereas white matter abnormalities tended to be more frequent in premature children, cortical laminar abnormalities tended to occur more frequently in term neonates and older children. The presence of cortical laminar abnormalities on MRI was correlated with an increased risk of spasticity in children without concomitant white matter abnormalities. In children with white matter lesions, cortical laminar abnormalities did not contribute to the risk of spasticity, which was already highly increased by the presence of white matter damage. No association was found between cortical abnormalities on MRI and epilepsy or psychomotor retardation.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Diseases↗
PubMed1993

Decreased glucose oxidation in preterm infants fed a formula containing medium-chain triglycerides.

Several formulas for preterm infants contain medium-chain triglycerides (MCT) to enhance fat absorption. Although fat absorption with MCT was slightly higher in several studies in preterm infants, a beneficial effect on growth has only been reported in one publication. We hypothesized that when part of the fat blend of preterm formula is substituted by MCT oil, this might lead to a different metabolic pattern in which, due to the preferential oxidation of MCT, an increase in lipogenesis from glucose could lead to an increase in metabolic rate. To study the impact of MCT on glucose metabolism, 18 preterm infants were randomized to receive either an MCT or an LCT formula containing 38- and 6%-by-weight medium-chain fatty acids, respectively, in their fat blend. At 4 wk of age, the metabolic rate, substrate utilization, glucose kinetics, and oxidation were measured by indirect respiratory calorimetry in combination with a constant-rate oral infusion of [U-13C]glucose. The "true" rate of appearance of glucose (Ra "true") was measured from the dilution of the uniformly labeled (m + 6) species of infused tracer, whereas "apparent" rate of appearance of glucose (Ra "apparent") was measured from the dilution of infused tracer C (carbon). The latter was measured by an on-line combustion method using a gas chromatograph-isotope ratio mass spectrometer. At a carbohydrate intake of 8.4 mg.kg-1.min-1, total utilization of carbohydrate was equal in both groups at 7.6 mg.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary Carbohydrates↗
PubMed1993

Arterial blood pressure wave forms in radial and posterior tibial arteries in critically ill newborn infants.

The aim of this study was to document arterial blood pressure wave forms at two sites along the arterial tree of the neonate: in the radial and posterior tibial arteries. Using a high-fidelity catheter tip-transducer system, peripheral arterial blood pressure wave forms in 26 critically newborn infants were studied. In 14 infants the radial artery and in 12 infants the posterior tibial artery was cannulated. Radial artery blood pressure waves resembled those of proximal aortic rather than those of the radial artery in adults. Quantitative analysis of the waves was performed to reassure this finding. Blood pressure waves obtained from posterior tibial artery resembled those of femoral artery rather than those of posterior tibial artery waves in adults. We conclude that radial and posterior tibial artery wave forms in neonates appear to have a central appearance. This phenomenon might be explained by the close proximity of the radial and posterior tibial artery to the central aorta and femoral artery respectively, due to the small and short limbs of the neonate. The finding allows an "easy central pressure look" at both ends of the neonatal aorta.

Birth Weight↗
PubMed1992

Comparison of two preterm formulas with or without addition of medium-chain triglycerides (MCTs). II: Effects on mineral balance.

Medium-chain triglycerides (MCTs) are included in the fat blend of several preterm formulas because of their complete absorption and rapid oxidation. The effects of two different fat blend compositions on calcium (Ca), phosphorus (P), and magnesium (Mg) balances and plasma levels and on plasma levels of parathyroid hormone (PTH), alkaline phosphatase (AP), and 1,25-dihydroxyvitamin D [1,25-(OH)2D] were investigated in 28 healthy very-low-birth weight infants at 4 weeks of age. A preterm formula with a traditional corn oil/MCT blend containing 38% MCTs (MCT group) was compared to a new fat blend, designed to resemble human milk more, containing 6% MCTs (LCT group). There was a higher absorption of Ca in the MCT group (73% vs. 60%. p less than 0.005), and an equal absorption of P (both 92%). The excretion of Ca correlated with the excretion of fat (p less than 0.00005). The LCT group showed a higher median PTH level (MCT: 2.1 pmol/L, LCT: 4.7 pmol/L, p less than 0.01) and a higher urinary P excretion (p less than 0.001). Mg absorption was also lower with LCT, but retention of Mg exceeded intrauterine values in both groups. Mineral plasma levels were in the normal range in both groups. AP was not different between groups and in the upper part of the reference range, whereas 1,25-(OH)2D levels were above the normal range and also not different between groups. We conclude that with the LCT formula, Ca absorption is slightly lower than with the MCT formula, whereas P absorption is unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1991

Comparison of short term indirect calorimetry and doubly labeled water method for the assessment of energy expenditure in preterm infants.

The accuracy of 8-hour indirect calorimetry (IDC) as an estimate of energy expenditure was investigated in 8 healthy preterm infants (birth weight 1,270 +/- 193 g, gestational age 32 +/- 3 weeks, mean +/- SD) in comparison with an analysis over 5 days using the doubly-labeled water (2H2(18)O) method (DLW). The infants that were fed continuously by nasogastric drip with 120 kcal/kg/day of special infant formula were measured twice under thermoneutral conditions in a closed system indirect calorimeter during 8 h with a 4-day interval; simultaneously isotope decay was measured by isotope ratio mass spectrometry in urine samples collected daily during 5 days from 6 h after an oral dose of 2H2(18)O on the first day of IDC, all during the 4th postnatal week. The mean differences between carbon dioxide production rate (rCO2) measured either by single 8-hour IDC or by duplicate 8-hour IDC and the 5-day DLW method, using the two-point analysis or the multipoint analysis were not significantly different from zero. The rCO2 calculated from the DLW method using the two-point analysis differed -1.4 +/- 1.7% from that measured by the multipoint analysis. The mean differences between the metabolic rate estimated from 8 h of IDC and from the 5-day DLW method based on a measured RQ of 0.90 was -6.7 +/- 6.2% and based on the RQ of the feeding -4.5 +/- 6.0%. These differences were not significantly different from zero. We conclude that IDC over 8 h and two-point DLW measurement over 5 days, both methods that can be applied with relative ease in practice, offer an adequate average estimate of energy expenditure in continuously fed preterm infants under thermoneutral conditions.

Calorimetry, Indirect↗
PubMed1990

Effects of high carnitine supplementation on substrate utilization in low-birth-weight infants receiving total parenteral nutrition.

Parenterally fed preterm neonates are known to be at risk for carnitine deficiency. We studied substrate utilization in low-birth-weight infants receiving total parenteral nutrition (TPN) with (A) and without (B) supplementation of 48 mg carnitine.kg-1.d-1 on days 4-7 (birth weights 1334 +/- 282 vs 1318 +/- 248 g, gestational age 32 +/- 2 vs 32 +/- 2 wk, A vs B, respectively). TPN consisted of 11 g glucose.kg-1.d-1 and 2.4 g.kg-1.d-1 of both protein and fat. Plasma carnitine concentrations at day 7 were for free carnitine 11.8 +/- 5.0 vs 164 +/- 56 mumol/L and for acyl carnitine 3.8 +/- 2.0 vs 33.9 +/- 15.4 mumol/L, respectively. Indirect calorimetry at day 7 showed a higher fat oxidation (0.21, -0.31 to +0.60 vs 1.18, 0.70 to 1.95 g. kg-1.d-1, respectively, P less than 0.02, median and interquartile range) in group B and a higher protein oxidation (0.37, 0.30-0.43 vs 0.63, 0.53-0.88 g.kg-1.d-1, P less than 0.001). The time to regain birth weight was also higher in group B (7, 5.5-9 vs 9, 7-14 d, P less than 0.05). Carnitine supplementation and calorie intake were the best explanatory variables for metabolic rate (R2 = 0.45, P less than 0.002). We conclude that carnitine supplementation of TPN in this dosage does not seem advisable.

Calorimetry, Indirect↗