Oskar Baenziger

The Influence of the Timing of Cord Clamping on Postnatal Cerebral Oxygenation in Preterm Neonates: A Randomized, Controlled Trial

OBJECTIVE. Our goal was to investigate the effect of placentofetal transfusion on cerebral oxygenation in preterm infants by near-infrared spectroscopy. SUBJECTS. A total of 39 preterm infants with a median gestational age of 30.4 weeks were randomly assigned to an experiment group (n = 15) and a control group (n = 24). INTERVENTIONS. The delivery of the infants in the experiment group was immediately followed by maternal administration of syntocinon, the infant was placed 15 cm below the placenta, and cord clamping was delayed by 60 to 90 seconds. The infants in the control group were delivered conventionally. At the ages of 4 and 24 hours, cerebral hemoglobin concentrations, cerebral blood volume, and regional tissue oxygenation were measured by near-infrared spectroscopy. RESULTS. Cerebral blood volume was not different between the 2 groups at the age of 4 hours (6.1 vs 5.8 mL/100 g of tissue) nor at the age of 24 hours (6.2 vs 6.2 mL/100 g of tissue). Mean regional tissue oxygenation of the experiment group was higher at the ages of 4 hours (69.9% vs 65.5%) and of 24 hours (71.3% vs 68.1%). CONCLUSION. Delayed clamping of the umbilical cord improves cerebral oxygenation in preterm infants in the first 24 hours.

The effect of ductal diameter on surgical and medical closure of patent ductus arteriosus in preterm neonates: size matters.

OBJECTIVEnWe sought to analyze the effect of patent ductus arteriosus diameter on treatment success in premature neonates.nnnMETHODSnAmong 537 consecutive neonates born between 1985 and 2005 with a diagnosed patent ductus arteriosus, 201 premature patients (<35 weeks gestation) treated for a hemodynamically significant patent ductus arteriosus were retrospectively reviewed. Two groups were compared: group MED (n = 154; successful treatment with indomethacin) and group FAIL (n = 47; failure of medication to reduce the patent ductus arteriosus diameter to hemodynamic insignificance).nnnRESULTSnAfter unsuccessful medical treatment, 33 patients required surgical patent ductus arteriosus closure, 12 died before further possible treatment, and 2 were discharged home without clinical symptoms but with an open patent ductus arteriosus. Mean patent ductus arteriosus diameter in the FAIL group (2.8 +/- 0.9 mm) was significantly larger than that in the MED group (2.4 +/- 0.6 mm, P < .01). Assisted respiration time (ventilation plus continuous positive airway pressure) before patent ductus arteriosus closure was longer in the FAIL group (20 days) than in the MED group (9 days, P < .001) but was similar after patent ductus arteriosus closure. By using an index of patent ductus arteriosus diameter squared/birth weight (in square millimeters per kilogram), a cutoff value of less than 9 mm2/kg correctly predicts medical patent ductus arteriosus closure in 87.5% of patients. Values of greater than 9 mm2/kg correctly predict medication failure in 41.5% of patients.nnnCONCLUSIONSnIn preterm babies requiring surgical patent ductus arteriosus closure, longer respiration times reflect a delay while attempting medical treatment, but respiration time is equally short between groups after shunt elimination. Medical treatment, although a valid first option, is likely to fail with larger patent ductus arteriosus diameters and lower birth weights. Unwarranted assisted respiration and corresponding hospital stay might be shortened by earlier surgical referral for patent ductus arteriosus closure in preterm babies with a patent ductus arteriosus index of greater than 9 mm2/kg.

Tissue oxygen saturation measured by near infrared spectrophotometry correlates with arterial oxygen saturation during induced oxygenation changes in neonates.

The aim of this study was to compare quantitatively the changes in tissue oxygen saturation (TOS), determined by two algorithms (TOSc and TOSa) based on near-infrared spectrophotometry, to the changes in arterial oxygen saturation (SaO2) measured by pulse oximetry. TOSc is an algorithm derived by the manufacturer (Critikon) based on a modified Beer-Lambert law; TOSa, our own algorithm, uses the diffusion approximation of light transport for the semi-infinite boundary condition. Slow changes of more than 3% in SaO2 were carried out in 20 mechanically ventilated neonates by altering the inspired oxygen fraction. For each change the regression lines of TOSc versus SaO2, TOSa versus SaO2 and TOSc versus TOSa were calculatcd. For each infant the mcan slope, intercept and r2 of these lines were determined. In 18 preterm infants we obtained median 9.5 (range one to 13) measurements corresponding to a total of 166 measurements. The mean SaO2 was 91.6 (SD 2.3)%, TOSc was 64.7 (SD 7.2)% and TOSa was 71.4 (SD 11.0)%. Changes in TOSc and TOSa were strongly correlated to changes in SaO2 (r2 = 0.86 and r2 = 0.87). TOSc considerably but systematically underestimated the size of the change: delta TOSc = 0.49 delta SaO2. TOSa quantified changes reasonably correctly: delta TOSa = 0.90 delta SaO2. Changes in TOSc and TOSa were highly correlated (r2 = 0.98). These results are promising, but the large inter-individual variation requires further work.

CO2 Reactivity of the Cerebral Hemoglobin Concentration in Healthy Term Newborns Measured by Near Infrared Spectrophotometry

CO2 reactivity of cerebral hemoglobin concentration was studied in 16 healthy term neonates on days 1 and 4 after birth using the near infrared spectrophotometry (NIRS) technique. The aim was to establish data on the physiological range of CO2 reactivity in healthy newborns and to investigate the influence of postnatal age on it. The CO2 reactivity measured by NIRS is expressed as the change of the total cerebral hemoglobin concentration (tHbR) per change of CO2 tension in µmol/l/kPa. We evaluated CO2 reactivity during increases and decreases of transcutaneous CO2 partial pressure and found in our methodological setting the data of the increases more reliable. In all infants but 1 we found a tHbR on day 1 with a mean value of 8.19 µmol/l/kPa (–1.39 to 18.87), in all infants on day 4 with a mean value of 9.54 µmol/l/kPa (2.76–25.88). There is a trend to higher values between day 1 and day 4 (difference = 2.25 µmol/l/kPa; p = 0.08). The noninvasive NIRS technique enabled us to test the cerebrovascular CO2 reactivity of the tHbR for the first time in healthy term newborns. Data on its physiologic range and variability are presented and compared to findings from ventilated infants and other age groups. As the CO2 reactivity might be an indicator for infants at risk of cerebral damage, it is necessary to have data on the physiological range of this parameter.

Cerebral blood flow and neurological outcome in the preterm infant

Abstract Cerebral blood flow (CBF) studies have provided some insight into pathophysiological mechanisms of cerebral damage in newborn children; their value in predicting brain damage, however, remains elusive. The purpose of our study was to evaluate the role of CBF measurements in predicting developmental outcome in preterm neonates at 18 months. Preterm babies with a gestational age of less than 34 weeks and a birth weight of less than 1500u2009g (nu2009=u200971) were enrolled in the study. CBF was measured by the nonivasive intravenous 133Xe method on three different occasions. We classified our measurements into three groups: depending on the time when performed group 1: between 2 and 36u2009h (nu2009=u200952); group 2: between 36 and 108u2009h (nu2009=u200944); group 3: between 108 and 240u2009h (nu2009=u200941). At the age of 18 months neurodevelopment testing was performed according to the Bayley mental and motor scales. Surviving infants had a higher mean CBF over the three groups than non surviving children (15.2u2009±u20093.5u2009ml/100u2009g brain tissue/min vs 13.0u2009±u20092.1u2009ml/100u2009g brain tissue/min, Pu2009<u20090.05). There was no correlation of CBF with mental or motor development in our study population in either of the three groups.nConclusion In preterm infants basal CBF is higher in surviving than in non surviving infants, but there is no correlation of resting CBF and later neurological outcome.

Testing near-infrared spectrophotometry using a liquid neonatal head phantom

We constructed a liquid phantom, which mimics the neonatal head for testing near infrared spectrophotometry instruments. It consists of a spherical, 3.5 mm thick layer of silicone rubber simulating skin and bone and acts as container for a liquid solution with IntralipidTM, 60 micrometers ol/l haemoglobin and yeast. The IntralipidTM concentration was varied to test the influence of scattering on haemoglobin concentrations and tissue oxygenation determined by the Critikon 2020. The solution was oxygenated using pure oxygen and then deoxygenated by the yeast. For the instruments algorithm, we found with increasing scattering (0.5%, 1%, 1.5% and 2% IntralipidTM concentration) an increasing offset added to the oxy- (56.7, 90.8, 112.5, 145.2 micrometers ol/l respectively) and deoxyhaemoglobin (25.4, 44.3, 58.5, 65.9 micrometers ol/l) concentration causing a decreasing range (41.3, 31.3, 25.0, 22.2%) of the tissue oxygen saturation reading. However, concentration changes were quantified correctly independently of the scattering level. For an other algorithm based on the analytical solution the offsets were smaller: oxyhaemoglobin 12.2, 34.0, 53.2, 88.8 micrometers ol/l and deoxyhaemoglobin 1.6, 11.2, 22.2, 28.1 micrometers ol/l. The range of the tissue oxygen saturation reading was higher: 71.3, 55.5, 45.7, 39.4%. However, concentration changes were not quantified correctly and depended on scattering. This study demonstrates the need to develop algorithms, which take into consideration the anatomical structures.

Oxygen Extraction Index Measured By Near Infrared Spectroscopy - A Parameter For Monitoring Tissue Oxygenation?

The objective was to assess the ability of near infrared spectrophotometry (NIRS) to detect changes in tissue oxygenation due to alterations in oxygen delivery. Ten hemodynamically stable preterm neonates with a median gestational age of 27.9 weeks (range 25.1-31.2), a median birth weight of 840g (range 690-1310), and a postnatal age of 29 days (range 2-45) were included in this prospective trial. Tissue oxygenation of the lower leg was measured by NIRS and the oxygen extraction index (OEI) was calculated prior and after a transfusion of 10-20 ml/kg body weight packed red blood cells. The OEI decreased from 0.31 (range 0.13-0.39) to 0.24 (range 0.12-0.36, p<0.005). This decrease correlated positively with the weight matched amount of packed red cell transfusion (r2=0.40, p<0.05) and with the increase in hematocrit (r2=0.58, p<0.005). The OEI obtained by a NIRS may allow to monitor changes in tissue oxygenation.

Comparison of Absolute Cerebral Haemoglobin Concentration in Neonates Measured Directly and by the Oxygen Swing Method both Based on Near Infrared Spectrophotometry

The total cerebral haemoglobin concentration (tHb in mumol/l) as a major indicator of the oxygen transport capacity is investigated in neonates. Two methods to determine tHb by near infrared spectrophotometry (NIRS) have evolved so far: The first method requires a slow oxygenation change with reference to arterial oxygen saturation (tHbo-method). The second method is based on a geometrical principle and a two channel NIRS instrument (tHbg-method). The aim of this study was to compare both methods quantitatively. 15 clinically stable preterm infants needing supplemental oxygen were included in this study. For each method the measurements of three infants were excluded due to unsatisfactory measurement quality. The remaining 9 neonates had a mean gestational age of 29 (range 25.1 to 31.4) weeks, birthweight of 1272 (740 to 1690) g and a postnatal age of 2.6 (0.5 to 5) days. In each infant 6 tHbo measurements were carried out. During each tHbo measurement the mean of the continuously available tHbg (Cerebral Redox Monitor 2020, Johnson & Johnson Medical) was calculated. The mean of all successful tHbo and corresponding tHbg was determined for each infant. The mean tHbg was 151 mumol/l (range 62 to 223 mumol/l) and the mean tHbo was 59 mumol/l (27 to 113 mumol/l). The regression line between the two methods was tHbg = 1.34 x tHbo + 72 mumol/l. The r was 83.6%. The correlation suggests, that both methods can be applied to measure tHb. However, it has to be taken into account that the tHbg-method returns significantly higher values than the tHbo-method.

The influence of placento-fetal transfusion (PFT) on the cerebral oxygenation of preterm neonates

The influence of placento-fetal transfusion (PFT) on the cerebral oxygenation of preterm neonates

Cerebral Blood Flow Measurements by Near Infrared Spectrophotometry in Reflectance Mode Are Valid in Neonates

sensitivity of SPM is-in the absence of valid multiple comparison correction-likely to be incorrectly high. The principal difficulty in your case, remarked Holxad mes in his didactic manner, lay in the fact of there being too much evidence. What was vital was overlaid and hidden by what was irrelevant (Doyle, 1894). Second, Holmes and colleagues claimed a similar lack of consistency in the visual comparison that the reader is asked to make between Figs. 2 and 3. In fact, we did not state those two figures to be comparable at all. For visual comparison, we provided Fig. 4 to illustrate the advantage of SHERLOCK over SPM95, as detailed in our text. However, to our disappointment, by applying Holmes method to a well-known activation paradigm in our study, we showed that its sensitivity can be changed at will by varying the filter kernel size, with more and more of the brain becoming significantly activated as the kernel size increases, inevitably paralleled by a dexad crease in resolution. In general, every claim of validity has to supply a valid model of the activations spatial distribution-beyond any doubt a still unsolved question, but it needs a great deal of supplementing before anyxad one could offer an opinion (Doyle, 1892).