Willem Baerts

Perfusion Index in Preterm Infants during the First 3 Days of Life: Reference Values and Relation with Clinical Variables

Background: The perfusion index (PI) derived from pulse oximetry readings represents the ratio of pulsatile (arterial blood) and nonpulsatile contributors to infrared light absorption. PI has been shown to correlate with cardiac performance. In theory, PI is readily available on every pulse oximeter; therefore, no additional sensors or infant handling are required. Currently, reference values are lacking in (preterm) neonates and the association with common clinical conditions is unclear. Objectives: To establish reference values for the PI in premature infants and at the same time determine the influence of common clinical conditions. Methods: PI was prospectively monitored on the lower limb for 72 h in 311 neonates born with a gestational age <32 weeks between January 2011 and December 2013. Longitudinal mixed-effects modeling was used. Linear, quadratic, and cubic models were explored. Main effects and interactions were investigated. Results: A squared model (0-24 h) followed by a linear model (24-72 h) provided the best fit of the data. PI was lowest around 12-18 h after birth and showed a steady increase thereafter. PI was positively related with female gender, gestational age, and pulse pressure. Negative associations were found with SIMV/HFOV ventilation, dopamine administration, mean arterial blood pressure, and arterial oxygen saturation. Although more complex, the general association with a patent ductus arteriosus was positive. Conclusion: PI varied according to several clinical conditions. The association with common clinical factors suggests that PI might be used for monitoring neonatal hemodynamics and possibly as an additional guidance for interventions.

Reduction in Cerebral Oxygenation due to Patent Ductus Arteriosus Is Pronounced in Small-for-Gestational-Age Neonates

Background: A haemodynamically significant patent ductus arteriosus (hsPDA) reduces cerebral oxygenation in appropriate-for-gestational-age (AGA) preterm neonates. Reduced cerebral oxygenation has been associated with brain injury. Preterm small-for-gestational-age (SGA) neonates show higher cerebral oxygenation than AGA peers throughout the first postnatal days. To date, no studies have investigated the effect of hsPDA on cerebral oxygenation in preterm SGA neonates. Objective: We aimed to assess the effect of hsPDA on cerebral oxygenation in preterm SGA neonates compared to AGA peers. We hypothesised that higher baseline cerebral oxygenation would reduce the impact of hsPDA on cerebral oxygenation in preterm SGA neonates. Methods: We monitored regional cerebral oxygen saturation (rScO2) with near-infrared spectroscopy and calculated the cerebral fractional tissue oxygen extraction (cFTOE) for 72 h after birth. Retrospective analysis compared 36 preterm SGA neonates (birth weight <10th percentile, 18 with hsPDA) to 36 preterm AGA neonates (birth weight 20th to 80th percentile, 18 with hsPDA). Results: In contrast to the other groups, SGA-hsPDA neonates demonstrated a significant fall in rScO2 [69% (SEM 2.5) at 4-8 h to 61% (2.7) at 68-72 h, p < 0.001] with a concurrent rise in cFTOE [0.26 (0.026) at 4-8 h to 0.34 (0.030) at 68-72 h, p < 0.001]. Conclusions: Contrary to our hypothesis, hsPDA had a significant negative effect on cerebral oxygenation in preterm SGA neonates. Future studies should explore the potential benefits of early screening and treatment for hsPDA on long-term neurodevelopmental outcome in preterm SGA neonates.

Tocolytic indomethacin: effects on neonatal haemodynamics and cerebral autoregulation in the preterm newborn

Background Indomethacin has vasoactive properties in cerebral and systemic vascular beds, and it improves cerebral autoregulatory ability. We speculated that tocolytic indomethacin will improve cerebral autoregulatory ability in the very preterm infant in early postnatal life. Methods Eighteen stable preterm infants gestational age (GA) 25.3–29.6 weeks, birth weight (BW) 660–1430 grams), whose mothers had received 50–150 mg of tocolytic indomethacin within 24 h before birth, and 18 individually matched controls (GA 25.0–29.7 weeks, BW 700–1390 grams) were studied four times for 15 min in the first 24 h of life. Autoregulation was assessed by determining correlations between mean arterial blood pressure (MABP (mm Hg)) and near-infrared spectroscopy-monitored cerebral oxygenation (rScO2). Results MABPs were significantly higher in the indomethacin infants than in the control infants (p=0.03). A decreased ability to autoregulate was found in four of the indomethacin infants, and in six of the control infants, which is not significantly different. Conclusions Prenatally administered indomethacin, given as a tocolytic in doses of 50–150 mg per day, improved transitional circulation in very preterm infants by significantly raising the MABP. It did not have an effect on the ability to autoregulate the cerebral circulation. In this study, no differences in short-term outcomes, like haemorrhagic or ischaemic cerebral lesions, were observed.

Carbon Dioxide Fluctuations Are Associated with Changes in Cerebral Oxygenation and Electrical Activity in Infants Born Preterm

OBJECTIVES To evaluate the effects of acute arterial carbon dioxide partial pressure changes on cerebral oxygenation and electrical activity in infants born preterm. STUDY DESIGN This retrospective observational study included ventilated infants born preterm with acute fluctuations of continuous end-tidal CO2 (etCO2) as a surrogate marker for arterial carbon dioxide partial pressure, during the first 72 hours of life. Regional cerebral oxygen saturation and fractional tissue oxygen extraction were monitored with near-infrared spectroscopy. Brain activity was monitored with 2-channel electroencephalography. Spontaneous activity transients (SATs) rate (SATs/minute) and interval between SATs (in seconds) were calculated. Ten-minute periods were selected for analysis: before, during, and after etCO2 fluctuations of ≥5  mm Hg. RESULTS Thirty-eight patients (mean ± SD gestational age of 29 ± 1.8 weeks) were included, with 60 episodes of etCO2 increase and 70 episodes of etCO2 decrease. During etCO2 increases, brain oxygenation increased (regional cerebral oxygen saturation increased, fractional tissue oxygen extraction decreased; P < .01) and electrical activity decreased (SATs/minute decreased, interval between SATs increased; P < .01). All measures recovered when etCO2 returned to baseline. During etCO2 decreases, brain oxygenation decreased (regional cerebral oxygen saturation decreased, fractional tissue oxygen extraction decreased; P < .01) and brain activity increased (SATs/minute increased, P < .05), also with recovery after return of etCO2 to baseline. CONCLUSION An acute increase in etCO2 is associated with increased cerebral oxygenation and decreased brain activity, whereas an acute decrease is associated with decreased cerebral oxygenation and slightly increased brain activity. Combining continuous CO2 monitoring with near-infrared spectroscopy may enable the detection of otherwise undetected fluctuations in arterial carbon dioxide partial pressure that may be harmful to the neonatal brain.

Effects of caffeine on the preterm brain: An observational study

BACKGROUND AND AIM Caffeine improves neurodevelopmental outcome of preterm infants. This study analyses the effects of caffeine on the neonatal brain. We hypothesized that caffeine has a neuroprotective effect through an increase in oxygen metabolism; reflected by increased cerebral oxygen extraction, electrical function, and perfusion. METHODS Preterm infants <32 weeks gestation (GA) receiving their primary dose caffeine-base (10 mg/kg) were included. Ten minutes of stable monitoring were selected before, during, and every hour up to 6 h after caffeine. Near-infrared spectroscopy monitored regional cerebral oxygenation (rScO2) and extraction (FTOE). Amplitude-integrated electroencephalogram (aEEG) monitored minimum, mean and maximum amplitudes. Spontaneous activity transients (SAT) rate and the interval between SATs (ISI) were calculated. Mean arterial blood pressure (MABP), heart rate (HR) and arterial oxygen saturation (SaO2) were monitored. Arterial pCO2s were collected before and 4 h after caffeine. Brain perfusion was assessed 1 h before and 3 h after caffeine by Doppler-measured resistance-index (RI), peak systolic velocity (PSV) and end-diastolic velocity (EDV), in the anterior cerebral artery (ACA) and internal carotid artery (ICA). Results were presented in mean ± SD. RESULTS 34 infants, mean GA 28.8 ± 2.1 wk, were included. rScO2 significantly decreased from 69 ± 11 to 63 ± 12 1 h after caffeine, and recovered at 6 h (66 ± 10). FTOE increased correspondingly. MABP and HR increased significantly. PSV in the ACA decreased slightly. Other Doppler variables, aEEG parameters, and SaO2 were unaffected. CONCLUSION Caffeine increases oxygen extraction, suggesting a (transient) stimulating effect on brain metabolism. However, no substantial changes were found in brain perfusion and in electrical brain activity.

Contents Vol. 108, 2015

K. Allegaert, Leuven S. Andersson, Helsinki E. Bancalari, Miami, Fla. D. Bassler, Zurich J. Bhatia, Augusta, Ga. C. Bührer, Berlin W. Carlo, Birmingham, Ala. R. Christensen, Salt Lake City, Utah T. Curstedt, Stockholm C. Dani, Florence B. Darlow, Christchurch M. Hallman, Oulu W.W. Hay, Jr., Aurora, Colo. S.E. Juul, Seattle, Wash. M. Kaplan, Jerusalem B. Kramer, Maastricht R.J. Martin, Cleveland, Ohio C.J. Morley, Cambridge J. Neu, Gainesville, Fla. P.C. Ng, Hong Kong M.W. Obladen, Berlin W.S. Park, Seoul A.G.S. Philip, Sebastopol, Calif. M. Roth-Kleiner, Lausanne E. Saliba, Tours O.D. Saugstad, Oslo M.S. Schimmel, Jerusalem M.P. Sherman, Columbia, Mo. E.S. Shinwell, Tsfat K. Simmer, Perth, W.A. J. Smith, Tygerberg R.F. Soll, Burlington, Vt. (Cochrane Review Updates) B. Sun, Shanghai N. Takahashi, Tokyo N. Vain, Buenos Aires F. van Bel, Utrecht J.N. van den Anker, Washington, D.C. M. Vento Torres, Valencia F.J. Walther, Leiden M. Weindling, Liverpool J.A. Widness, Iowa City, Iowa T.F. Yeh, Taipei Fetal and Neonatal Research