Biomedical subjects

Hugo Devlieger

Publications and source records attributed to Hugo Devlieger.

24 records · Page 2Linked to original sources

PubMed2003

Nonlinear analysis of heart rate variability in infants with apparent life-threatening events.

Some studies have shown that neonates having experienced an Apparent Life-Threatening Event (ALTE) have an increased risk of dying of the Sudden Infant Death Syndrome (SIDS). In this study the heart rate variability in neonates has been analyzed through a study of the long range correlations and scale invariance (self-similarity) in their cardiac rhythm. The goal is to see whether it is possible to distinguish normal infants from infants with ALTEs using the previously mentioned nonlinear measures of the heart rate variability. Twelve ALTE infants are included in this study. To determine the degree to which these neonates suffer from ALTEs two examinations are performed: a polysomnography and home monitoring. Using the nonlinear measures obtained from the nonlinear analysis of the heart rate variability, the group suffering most from ALTEs can clearly be separated from the other neonates.

Heart↗

PubMed2003

Measurement of tissue oxygenation index during the first three days in premature born infants.

No normal values of tissue oxygenation index (TOI) of the brain are known regarding premature born infants. We measured TOI, a measure for the cerebral hemoglobin oxygen saturation, on the head of 15 preterm infants with a median postmenstrual age of 28 weeks (interquartile range (IQR) between 26-29 weeks) with spatially resolved spectroscopy (NIRO 300, Hamamatsu) during the first three days of life. Infants with intra-ventricular hemorrhage or periventricular leucomalacia before the first measurement, as shown by ultrasound, were excluded. The first measurement was done within the first 6 hours of life, the second and third measurement at, respectively, 24 and 48 hours after this first measurement. The mean TOI was calculated if saturation did not change by more than 5% for at least 30 minutes. Other parameters measured were PaO2, PCO2, pH, mean arterial blood pressure, heart rate, hemoglobin, glycemia and peripheral oxygen saturation. There was a significant increase of TOI after 24 (p < 0.05) and 48 (p < 0.001) hours. The median TOI on the first day was 57% (95% CI: 54-65.7), 66.1% on the second day (95%CI: 61.9-82.3%) and 76.1% on the third day (95%CI 67.8-80.1%). No correlation was found between TOI and peripheral oxygen saturation, blood pressure, PaO2, PaCO2 and hemoglobin concentration after multiple regression analysis. TOI increases in the first three days in premature born babies. The increase of TOI is not due to an increase of oxygenation or mean arterial blood pressure. In our opinion, it reflects the increase in cerebral blood flow during the first three days.

Adult↗

PubMed2003

Quantitation of the concordance between cerebral intravascular oxygenation and mean arterial blood pressure for the detection of impaired autoregulation.

Since some important forms of brain injury in premature infants are caused in considerable part by disturbances in cerebral blood flow (CBF), it is important to be able to detect whether the cerebrovascular autoregulation, the mechanism by which CBF is maintained constant despite alterations in mean arterial blood pressure (MAP), is working properly. A recent study suggested that concordant changes in MAP and cerebral intravascular oxygenation (HbD), measured non-invasively by near-infrared spectroscopy (NIRS) as the difference between the concentration changes of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (Hb), reflect impaired cerebrovascular autoregulation. Consequently, premature infants with impaired cerebrovascular autoregulation could be identified by simultaneous, continuous measurements of HbD and MAP. From several premature babies, MAP, HbD and arterial oxygen saturation (SaO2) were measured simultaneously at the University Hospital Leuven, Belgium. The concordance between MAP and HbD was quantitated using three different measures, among which a newly developed measure that looks for similarity of the dynamics between signals. Some preliminary results obtained from the measured data are given.

Blood Pressure↗

PubMed2003

Perinatal growth characteristics and associated risk of developing threshold retinopathy of prematurity.

PURPOSE: To document perinatal growth characteristics in infants who developed threshold retinopathy of prematurity (ROP) in an attempt to describe prenatal and postnatal growth-related risk factors for threshold ROP. METHODS: To document birth weight as well as absolute and relative weight gain (g/d and g/kg/d) in the first 6 weeks of life in infants who developed threshold ROP and who were admitted to a single tertiary neonatal intensive care unit between 1996 and 2000. These data were compared (case-control approach) with infants of the same gestational age (GA) who did not developed threshold ROP. RESULTS: Small for gestational age (SGA; ie, weight <10th percentile for a given GA) and growth restriction (<25th percentile for a given GA) are risk factors for threshold ROP (relative risk = 3.7 and 4.5, respectively). Absolute weight gain (g/d) is also associated with an increased risk of developing threshold ROP (P<.05). In contrast, relative weight gain (g/kg/d) is not significantly different between threshold ROP infants and GA-matched controls. CONCLUSIONS: SGA and a birth weight below the 25(th) percentile are risk factors for threshold ROP. Postnatal weight and absolute weight gain (g and g/d, respectively) in the first 6 weeks of life are statistically significant but of less clinical relevance because smaller infants at birth stay relatively smaller during the first 6 weeks of life. Even with normal (ie, same weight as control infants) postnatal relative weight gain (g/kg/d), growth retarded or restricted infants at birth still have an increased risk of developing threshold ROP.

Birth Weight↗

PubMed2002

The flow-pressure plot: a new look on the patient-ventilator interaction in neonatal care.

Most modern neonatal ventilators have now a built-in flow sensor and, as a spin-off of their mechanical action, provide some information about lung function characteristics as compliance and resistance after computation of the flow and pressure signals. Additionally, respiratory graphics as volume-pressure and flow-volume plots can be displayed. In clinical practice, however, they are rarely used to refine the ventilator setting. A nonconventional flow-pressure plot is presented in this article, constructed from the volume or flow, and pressure outputs of a Babylog 8000 (Dräger, Lübeck, Germany). This flow-pressure diagram appears to be useful in the real-time computation of respiratory mechanics based on the Rahn's law of respiratory motion. Its major advantage, however, is the easy pattern recognition of subtle changes in infant-ventilator interaction, ie, excessive triggering, fighting against the ventilator, augmented breath, tube subobstruction. It may be useful to add the flow-pressure plot to the classical respiratory graphics allowing to monitor mechanical ventilation more accurately and to fine tune the ventilator setting accordingly.

Equipment Design↗

PubMedDate not supplied

Structural and functional outcome in infants treated with cryotherapy for threshold retinopathy between 1989 and 1999.

PURPOSE: To assess visual outcome, funduscopic appearance, and refraction for infants treated with cryotherapy for threshold retinopathy of prematurity (ROP) between 1989 and 1999. METHODS: Retrospective analysis of the medical records of premature infants with threshold ROP who were treated with cryotherapy. RESULTS: A total of 2,146 premature infants were screened for ROP during the study period. Of the 66 infants who were subsequently treated for threshold ROP with cryotherapy, 58 infants had at least 1 year of follow-up and comprised the study population. After correcting for improved survival, the overall incidence of treated infants with cryotherapy increased during the study period. Comparison of infants treated from 1989 through 1995 (group 1; n=26) and 1996 through 1999 (group 2; n=32) showed group 2 infants had improved visual outcome, better funduscopic anatomic appearance, and decreased myopia. CONCLUSION: Although the incidence of treated premature infants increased during the study period, visual outcome improved. The literature attributes improved visual and anatomical outcome to the use of the diode laser in the treatment of threshold ROP. In this study, the improved visual and anatomical results obtained with cryotherapy could be attributed in part to the development over the years of a milder type of retinopathy of prematurity and to earlier treatment of threshold ROP.

Cryosurgery↗