Fractional Oxygen Research Articles

Near-Infrared Spectroscopy Monitoring, Superior Vena Cava Flow, and Neurodevelopmental Outcome at 2 years in a Cohort of Very Low-Birth-Weight Infants

Objective We aimed at assessing the association between superior vena cava flow (SVCf), regional (cerebral) tissue oxygen saturation (rSO2), and cerebral fractional oxygen extraction (CFOE) during the first 48 hours of life and 2-years neurodevelopmental outcome of very low-birth-weight infants (VLBW). Methods We prospectively studied 60 VLBW infants admitted to our neonatal intensive care unit; rSO2 was continuously monitored with near-infrared spectroscopy during the first 48 hours of life, SVCf was measured at 4 to 6, 12, 24, and 48 hours, and CFOE was calculated. Neurodevelopmental outcome was assessed at 24 months corrected age. Results The mean gestational age at birth was 27.9 weeks (standard deviation: 2.4); 8 infants died in the first 3 months of life, 6 were lost to follow-up, 46 survived and were followed up. At 24 months, 6 (13%) and 7 (15.2%) infants developed minor and major sequelae, respectively. Infants who died had higher CFOE (p < 0.001) and lower SVCf (p < 0.001) than infants surviving with sequelae. In turn, these had higher SVCf between 24 and 48 hours than those without sequelae (p < 0.001). Conclusion SVCf, rSO2, and CFOE patterns in the first days of life suggest cerebral hyperperfusion, related to loss of autoregulation and/or use of inotropic drugs, as a potential mechanism of cerebral injury.

Early hyperoxia burden detected by cerebral near-infrared spectroscopy is superior to pulse oximetry for prediction of severe retinopathy of prematurity.

ObjectiveFractional tissue oxygen extraction (FTOE) is a measure derived from cerebral near-infrared spectroscopy and simultaneous pulse oximetry (SpO2), capturing the proportion of oxygen delivered in arterial blood that is used by the target tissue. FTOE may provide a better proxy measurement of retinal hyperoxia than pulse oximetry alone and could provide insight into the risk for retinopathy of prematurity (ROP). In this study, we directly compared hyperoxia burden calculated from FTOE with hyperoxia burden calculated from SpO2 alone in order to assess the strength of association between hyperoxia and severe ROP.Study designInfants born before <30 weeks and weighing <1500g underwent synchronized SpO2 and FTOE recording over the first four days following birth. After error correction of the raw recording, hyperoxia burden was calculated as the percentage of the total SpO2 or FTOE recording with measurements exceeding defined thresholds (90/93/95% and 20/15/10%, respectively) and was compared to the outcome of severe ROP, defined as ROP requiring laser therapy, after controlling for important covariates.Result63 infants were included with a mean ± SD gestational age of 25.8 ± 1.5 weeks and birth weight of 898.5 ± 206.9g; 13/63 (20%) had severe ROP. SpO2 hyperoxia burden was not associated with severe ROP at any threshold. FTOE hyperoxia burden was associated with severe ROP at the 15% (p=0.04) and 10% (p=0.03) thresholds. Infants with severe ROP spent 20 and 50% more time exceeding the 15 and 10% thresholds, respectively, as compared to those without severe ROP.ConclusionIn the first 96h of life, FTOE, but not SpO2 hyperoxia burden is associated with severe ROP. These preliminary results suggest that NIRS may be a viable alternative technology for targeted oxygen saturation guidelines.

Carbogen-induced increases in tumor oxygenation depend on the vascular status of the tumor: A multiparametric MRI study in two rat glioblastoma models

The alleviation of hypoxia in glioblastoma with carbogen to improve treatment has met with limited success. Our hypothesis is that the eventual benefits of carbogen depend on the capacity for vasodilation. We examined, with MRI, changes in fractional cerebral blood volume, blood oxygen saturation, and blood oxygenation level dependent signals in response to carbogen. The analyses were performed in two xenograft models of glioma (U87 and U251) recognized to have different vascular patterns. Carbogen increased fractional cerebral blood volume, blood oxygen saturation, and blood oxygenation level dependent signals in contralateral tissues. In the tumor core and peritumoral regions, changes were dependent on the capacity to vasodilate rather than on resting fractional cerebral blood volume. In the highly vascularised U87 tumor, carbogen induced a greater increase in fractional cerebral blood volume and blood oxygen saturation in comparison to the less vascularized U251 tumor. The blood oxygenation level dependent signal revealed a delayed response in U251 tumors relative to the contralateral tissue. Additionally, we highlight the considerable heterogeneity of fractional cerebral blood volume, blood oxygen saturation, and blood oxygenation level dependent within U251 tumor in which multiple compartments co-exist (tumor core, rim and peritumoral regions). Finally, our study underlines the complexity of the flow/metabolism interactions in different models of glioblastoma. These irregularities should be taken into account in order to palliate intratumoral hypoxia in clinical trials.

Blood transfusion in preterm infants improves intestinal tissue oxygenation without alteration in blood flow.

The objective of the study was to investigate the splanchnic blood flow velocity and oximetry response to blood transfusion in preterm infants according to postnatal age. Preterm infants receiving blood transfusion were recruited to three groups: 1-7 (group 1; n = 20), 8-28 (group 2; n = 21) and ≥29 days of life (group 3; n = 18). Superior mesenteric artery (SMA) peak systolic (PSV) and diastolic velocities were measured 30-60 min pre- and post-transfusion using Doppler ultrasound scan. Splanchnic tissue haemoglobin index (sTHI), tissue oxygenation index (sTOI) and fractional tissue oxygen extraction (sFTOE) were measured from 15-20 min before to post-transfusion using near-infrared spectroscopy. The mean pretransfusion Hb in group 1, 2 and 3 was 11, 10 and 9 g/dl, respectively. The mean (SD) pretransfusion SMA PSV in group 1, 2 and 3 was 0·63 (0·32), 0·81 (0·33) and 0·97 (0·40) m/s, respectively, and this did not change significantly following transfusion. The mean (SD) pretransfusion sTOI in group 1, 2 and 3 was 36·7 (19·3), 44·6 (10·4) and 41·3 (10·4)%, respectively. The sTHI and sTOI increased (P < 0·01), and sFTOE decreased (P < 0·01) following transfusion in all groups. On multivariate analysis, changes in SMA PSV and sTOI following blood transfusion were not associated with PDA, feeding, pretransfusion Hb and mean blood pressure. Pretransfusion baseline splanchnic tissue oximetry and blood flow velocity varied with postnatal age. Blood transfusion improved intestinal tissue oxygenation without altering mesenteric blood flow velocity irrespective of postnatal ages.

Multisite Tissue Oxygenation Monitoring Indicates Organ-Specific Flow Distribution and Oxygen Delivery Related to Low Cardiac Output in Preterm Infants With Clinical Sepsis.

Cardiac output may be compromised in preterm infants with sepsis. Whether low cardiac output is associated with low tissue oxygen supply in these patients is unclear. The aim of the current study was to assess the association between cardiac output, assessed by echocardiography, and tissue oxygenation, measured with multisite near-infrared spectroscopy, in a cohort of preterm infants with clinical sepsis. Prospective observational cohort study. Level III neonatal ICU. Twenty-four preterm infants (gestational age < 32 wk) with clinical sepsis. None. Clinical and echocardiographic assessment of hemodynamics was performed within 48 hours of sepsis workup and repeated at least 24 hours later. We measured cerebral, renal, and intestinal tissue oxygen saturation using near-infrared spectroscopy during an hour of stable measurements directly preceding or following echocardiography and calculated fractional tissue oxygen extraction in each tissue. We determined Spearman correlation coefficients between fractional tissue oxygen extraction and right ventricular output corrected for patent foramen ovale flow, left ventricular output corrected for ductus arteriosus flow, and superior vena cava flow. Right ventricular output corrected for patent foramen ovale and left ventricular output corrected for ductus arteriosus flow both correlated significantly with intestinal fractional tissue oxygen extraction (ρ, -0.700; p = 0.036 and ρ, -0.604; p = 0.029, respectively). In contrast, no significant correlations were found between cardiac output measurements and cerebral and renal fractional tissue oxygen extraction, respectively. Changes in cardiac output measurements were not associated with observed changes in fractional tissue oxygen extraction values. Right ventricular output corrected for patent foramen ovale and left ventricular output corrected for ductus arteriosus flow, indicators of systemic blood flow in preterm infants with shunts, were negatively associated with intestinal fractional tissue oxygen extraction, but not with renal and cerebral fractional tissue oxygen extraction. These findings suggest that during low output states due to clinical sepsis intestinal perfusion is most at risk.

Correlation between Doppler flow patterns in growth-restricted fetuses and neonatal circulation.

To investigate whether prenatal Doppler parameters in growth-restricted fetuses are correlated with neonatal circulatory changes. In 43 cases of suspected fetal growth restriction (FGR), serial Doppler measurements of umbilical artery (UA) and middle cerebral artery (MCA) pulsatility index (PI) were performed. The last measurement, closest to delivery (< 1 week before birth), was used for analysis. Neonatal circulation was assessed for 2 h/day on Days 1-5, 8 and 15 by near-infrared spectroscopy (NIRS) of the cerebral, renal and splanchnic regions. We calculated fractional tissue oxygen extraction (FTOE) as: (arterial oxygen saturation - NIRS value)/arterial oxygen saturation. The following ratios were calculated: cerebroplacental ratio (CPR; MCA-PI/UA-PI), cerebrorenal ratio (CRR; cerebral/renal FTOE) and cerebrosplanchnic ratio (CSR; cerebral/splanchnic FTOE). Spearman's rank correlation coefficient (ρ) was calculated between prenatal Doppler parameters and neonatal NIRS variables. These analyses were carried out for the entire group, and separately for cases of early FGR (delivered < 34 weeks) and late FGR (≥ 34 weeks). Fetal Doppler parameters correlated with neonatal NIRS variables on Days 1-3: UA-PI correlated with renal FTOE (Day 1: ρ = 0.454, P < 0.01) and CRR (Day1: ρ = -0.517, P < 0.001). MCA-PI correlated with cerebral FTOE on Day 2 (ρ = 0.469, P < 0.01), approached statistical significance on Day 3 but was not correlated on Day 1. CPR correlated with CRR (Day 1: ρ = 0.474, P < 0.01). Most associations lost their statistical significance when early and late FGR subgroups were considered separately. Low MCA-PI and low CPR, indicating brain sparing before birth, are associated with low CRR after birth, indicating relatively greater blood flow to the cerebrum than to the renal region. Based on the results of this study, it could be speculated that if brain sparing is present in the fetal circulation, it persists during the first 3 days after birth. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Neonatal haemodynamic effects following foetal exposure to labetalol in hypertensive disorders of pregnancy

Objective: Hypertensive disorders of pregnancy (HDP) affect foetal outcome. Labetalol is frequently used to lower maternal blood pressure and prolong pregnancy. Conflicting evidence exists for specific neonatal side effects described after maternal labetalol treatment. Our aim was to investigate neonatal effects of foetal exposure to labetalol on cerebral oxygenation and extraction.Methods: In a prospective observational study, clinical characteristics, vital parameters and cerebral oxygen delivery and extraction were collected during the first 24 h of life in labetalol-exposed preterm neonates and compared with two control groups.Results: Twenty-two infants with a mean gestational age of 28.9 weeks, born from labetalol-treated mothers with HDP were included and matched with 22 infants with non-labetalol-treated mothers with HDP and 22 infants without maternal HDP. No significant differences between groups were found neither in heart rate, blood pressure and inotropic support, nor in mean regional cerebral oxygen saturation and fractional tissue oxygen extraction.Conclusion: Foetal labetalol exposure associated effects on preterm heart rate, blood pressure, cerebral oxygenation and extraction are not demonstrated. Maternal disease severity seems to play a more important role in neonatal cerebral haemodynamics. Maternal labetalol treatment has no clinically important short term side effects in the preterm neonate.

Near-Infrared Spectroscopy to Predict the Course of Necrotizing Enterocolitis.

ObjectivesTo investigate whether cerebral, liver, and infraumbilical regional tissue oxygen saturation (rSO2) and fractional tissue oxygen extraction (FTOE) could be used to diagnose necrotizing enterocolitis (NEC) and complicated NEC (Bell’s stage 3B or death) during its early stages.MethodsA prospective observational cohort study of preterm infants with suspected or diagnosed NEC. We compared the mean eight-hour cerebral, liver, and infraumbilical rSO2 and FTOE values of infants with no NEC and definite NEC and of infants with uncomplicated and complicated NEC in the first forty-eight hours after onset of symptoms, suspicious for NEC. Furthermore, we determined cut-off values by generating receiver operating characteristics curves in case of significant differences in the first eight-hour mean values of rSO2 between infants with no NEC and definite NEC and between infants with uncomplicated and complicated NEC.ResultsWe included 33 patients: 13 no NEC, 10 with uncomplicated NEC, and 10 with complicated NEC. We found no significant differences in the first twenty-four hours after onset of symptoms in rSO2 and FTOE between infants with no NEC and definite NEC. In preterm infants with complicated NEC, we observed significantly lower cerebral, liver, and infraumbilical rSO2 and higher FTOE within twenty-four hours after onset of symptoms compared with infants with uncomplicated NEC. A continuous cerebral rSO2 ≤ 71% and liver rSO2 ≤ 59% in the first eight hours after onset of symptoms predicted the onset of complicated NEC with a sensitivity of 1.0 and specificity of 0.8, and a sensitivity of 1.0 and specificity of 1.0, respectively.ConclusionsBy measuring the cerebral and splanchnic oxygenation it is possible to differentiate complicated NEC from uncomplicated NEC. In our sample, NIRS monitoring did not proof useful for distinguishing between definite NEC and no NEC in preterm infants with clinical signs suspicious of NEC.

Low cerebral activity and cerebral oxygenation during immediate transition in term neonates – a prospective observational study

Aim: To analyze whether in term neonates during immediate transition after birth low cerebral activity measured by amplitude-integrated EEG (aEEG) is linked to cerebral regional oxygen saturation (crSO2) measured by near-infrared spectroscopy (NIRS). Additionally, the cerebral fractional tissue oxygen extraction (cFTOE) was calculated to analyze whether cerebral activity is linked to cFTOE.

The Effect of Maternal Antihypertensive Drugs on the Cerebral, Renal and Splanchnic Tissue Oxygen Extraction of Preterm Neonates

Background: Drugs with antihypertensive action are frequently used in obstetrics for the treatment of preeclampsia (labetalol) and tocolysis (nifedipine) or for neuroprotection (MgSO₄), and may affect the hemodynamics of preterm born neonates. Objective: The aim of this study was to assess whether maternal antihypertensive drugs affect multisite oxygenation levels of the neonate. Methods: Eighty preterm neonates of ≤32 weeks of gestational age were monitored using near-infrared spectroscopy. Mean cerebral, renal and splanchnic fractional tissue oxygen extractions (cFTOE, rFTOE and sFTOE) were calculated for the first 5 postnatal days. We determined the effect of various maternal antihypertensive drugs on cFTOE and rFTOE using multilevel analysis, and on sFTOE using Kruskal-Wallis and Mann-Whitney U tests. Results: Eleven infants were exposed to labetalol ± MgSO₄, 7 to nifedipine ± MgSO₄, 20 to MgSO₄ only, and 42 to no maternal antihypertensive drugs. The infants exposed to labetalol ± MgSO₄ had a lower cFTOE on days 1 (0.14, p = 0.031), 2 (0.13, p = 0.035) and 4 (0.18, p = 0.046) than nonexposed infants on the corresponding days (0.22, 0.20 and 0.24, respectively). On day 2, cFTOE was also lower in infants exposed to nifedipine ± MgSO₄ (0.11, p = 0.028) and to MgSO₄ only (0.15, p = 0.047). sFTOE was higher in infants exposed to labetalol ± MgSO₄ on days 1 (µ = 0.71) and 2 (µ = 0.82) than in nonexposed infants (µ = 0.26, p = 0.04 and µ = 0.55, p = 0.007, respectively). Maternal antihypertensive drugs did not affect rFTOE. Conclusions: Low neonatal cFTOE found with maternal antihypertensive drug exposure may relate to either increased cerebral perfusion or neurologic depression induced by the medication, or preferential brain perfusion associated with preeclampsia placental insufficiency. Concomitantly high sFTOE found with labetalol exposure supports the latter, while renal autoregulation may explain rFTOE stability.

The relation between splanchnic ischaemia and intestinal damage in necrotising enterocolitis

ObjectivesThe underlying pathophysiology of necrotising enterocolitis (NEC) remains incompletely understood, particularly the role of intestinal perfusion. We aimed to determine the relation between cerebral and splanchnic fractional tissue oxygen extraction...

Low cerebral activity and cerebral oxygenation during immediate transition in term neonates—A prospective observational study

AimTo analyze whether in term neonates during immediate transition after birth low cerebral activity measured by amplitude-integrated EEG (aEEG) is linked to cerebral regional oxygen saturation (crSO2) measured by near-infrared spectroscopy (NIRS). Additionally, the cerebral fractional tissue oxygen extraction (cFTOE) was calculated to analyze whether cerebral activity is linked to cFTOE. MethodsA total of 244 term neonates delivered by primary cesarean section were studied. In addition to routine monitoring with pulse oximetry, aEEG and NIRS measurements were performed during the first 15min after birth. The mean minimum (Vmin) and maximum (Vmax) amplitude of the cerebral activity as well as crSO2 and cFTOE for each minute was determined. Neonates with initial Vmin<5μV or Vmax<10μV, which normalized during transition (study group) were compared to neonates with normal aEEG values throughout the whole monitoring period (control group). Results9 neonates fulfilled inclusion criteria to the study group and were compared to 50 neonates in the control group. Vmin, Vmax, crSO2, SpO2 and cFTOE were compared from the 4th to 15thmin after birth. During our study period, Vmin and Vmax were significantly lower in the study group than in the control group. crSO2 was significantly lower in the study group until minute 11, dropping below the 10th centile in minute 8. cFTOE was significantly higher in the study group until minute 10, rising above the 90th centile in minutes 8 and 9. SpO2 was within normal ranges in both groups. crSO2 and cFTOE were within normal ranges in the control group. ConclusionThe present study demonstrates that neonates with initially low cerebral activity during immediate transition after birth concurrently showed low crSO2 (<10th percentile), but increased cerebral oxygen extraction (cFTOE>90th percentile). Cerebral monitoring with aEEG and NIRS might provide useful information on the neonates’ condition during immediate transition.

Brain Maturity and Variation of Oxygen Extraction in Premature Infants.

Objectives The ability of the premature brain to extract and use oxygen has not been studied adequately. This study aimed to determine factors that influence fractional tissue oxygen extraction (FTOE) of the brain in premature infants using near-infrared spectroscopy (NIRS) and pulse oximetry. Study Design We prospectively studied FTOE in very low birth weight (BW) infants (< 1,500 g and ≤ 34 weeks' gestation). Factors affecting FTOE and its variability were examined using bivariate and linear regression models. FTOE variability was measured on two scales: short scales (3-20 seconds) and long scales (20-150 seconds). Results We examined 147 simultaneous NIRS and pulse oximetry recordings that were collected from 72 premature infants (gestational age [GA] = 28 weeks and BW = 1,036 g). In regression models, average FTOE correlated negatively with hemoglobin (Hb) and increased significantly in patients with severe intraventricular hemorrhage/periventricular leukomalacia. Both FTOE short- and long-scale variabilities correlated negatively with GA and positively with postnatal age (PNA). Moreover, FTOE long-scale variability was significantly reduced in infants supported with invasive ventilation. Conclusions In premature infants, cerebral oxygen extraction increased with reduced Hb and severe brain injury. Variability in oxygen extraction showed differential changes with GA and PNAs and was affected by invasive ventilation.

EEG maturation and stability of cerebral oxygen extraction in very low birth weight infants.

Fractional cerebral tissue oxygen extraction (FTOE) can be continuously monitored by simultaneous near-infrared spectroscopy (NIRS) and pulse oximetry. The objective of this study is to test the hypothesis that in very low birth weight (VLBW) infants, the more mature EEG activity is, the less variable FTOE is. A prospective study was conducted on VLBW infants (< 1500 g and ⩽ 34 weeks gestation) without significant brain injury. Simultaneous continuous two-channel electroencephalography (EEG), NIRS and pulse oximetry were recorded. Absolute and relative powers of EEG in the delta, theta, alpha, beta and total frequency bands have been calculated. FTOE variability was calculated on two scales: short scales (3 to 20 s) and long scales (20 to 150 s). FTOE variability was examined against changes in relative spectral power of different EEG bands. We evaluated 67 studies performed on 46 VLBW infants. Average study duration was 21.3 ± 5.5 h. Relative power of delta band positively correlated with FTOE short- and long-scale variability (r=0.45, P<0.001; r=0.44, P<0.001, respectively). Relative power of alpha bands negatively correlated with FTOE short- and long-scale variability (r=-0.38, P=0.002; r=-0.42, P<0.001, respectively). These correlations continued to be significant when controlling for sex, small for gestational age, postmenstrual age, being on respiratory support, hemoglobin concentration, systemic oxygen saturation and transcutaneous carbon dioxide tension. Increased maturation of EEG activity is associated with decreased variability in cerebral oxygen extraction. The implications of increased variability in FTOE on brain injury in premature infants need further exploration.

Effect of high fractional inspiratory oxygen on postoperative pulmonary function: a randomized–controlled study

Background Although a high fraction of inspired oxygen (FiO 2 ) could reduce surgical site infection, there is a concern that it could increase postoperative pulmonary complications, including hypoxemia. However, there is an advantage for preoperative high FiO 2 before induction of anesthesia as it decreases the incidences of desaturation and wound infection. Our aim was to assess whether different levels of FiO 2 affect pulmonary function tests. Patients and methods Ninety patients scheduled for elective abdominal hysterectomy were randomized to receive either preoxygenation with 1.0 FiO 2 for 3 min, then continued on 1.0 FiO 2 till the end of surgery (group A), or preoxygenation with 1.0 FiO 2 for 3 min, then continued on 0.4 FiO 2 till the end of surgery (group B), or preoxygenation with 0.4 FiO 2 then continued on 0.4 FiO 2 till the end of surgery (group C). The oxygenation index (PaO 2 /FiO 2 ) was measured every 30 min during anesthesia and 2 h after extubation. Pulmonary function test was measured on the morning of surgery and 2 h after extubation. Results Five minutes after intubation, the median PaO 2 /FiO 2 was 483 (371–490) mmHg in group A, 420 (336–490) mmHg in group B, and 450 (350–485) mmHg in group C ( P = 0.24). Two hours after extubation, the PaO 2 /FiO 2 was reduced to 333 (314–342) mmHg in group A, 328 (311–357) mmHg in group B, and 342 (303–316) mmHg in group C ( P = 0.55). The median functional vital capacity were 1950 (1600–2120), 1850 (1570–2250), and 1900 (1490–2020) ml at baseline and 1650 (1370–1953), 1670 (1340–2350), and 1711 (1412–2410) ml 2 h after extubation in groups A, B, and C, respectively ( P = 0.66). Conclusion We found no significant difference in the oxygenation index or pulmonary function tests between patients administered different levels of FiO 2 .

Oxygen therapy via high flow nasal cannula in pediatric intensive care unit.

The aim of the present study was to assess the efficacy and safety of oxygen therapy via high flow nasal cannula in pediatric patients with acute respiratory failure. Patients who were admitted to pediatric intensive care unit and were administered high flow nasal cannula (HFNC) therapy between January 2015 and January 2016 were enrolled. Arterial blood gas parameters, respiratory rates (RR), heart rates (HR), systolic, db > iastolic, and mean arterial pressures (SBP, DBP, MAP), dyspnea scores, fractional oxygen indices (FiO < sub > 2 < /sub > ), and oxygen saturations (SatO < sub > 2 < /sub > ) were recorded at baseline, 30 minutes, and 12 hours. The study enrolled a total of 50 patients of whom 24 (48%) were female and 26 (52%) were male. Statistically significant reductions occurred in mean HR and RR values at 30 minutes and 12 hours compared to those at 0 minute (p < 0.05). Significant increases were observed in SatO2 values at 30 minutes (p.0.001) and 12 hours (p:0.005) compared to SatO2 value at 0 minute (p < 0.05). Similarly, there occurred significant reductions in mean FiO < sub > 2 < /sub > values at 30 minutes and 12 hours compared to baseline (p < 0.05). Significant reductions occurred in mean dyspnea score at 30 minutes (p:0.001) and 12 hours (p:0.001) compared to that at 0 minute (p < 0.05). pH, PaCO < sub > 2 < /sub > , PaO < sub > 2 < /sub > , SBP, and DBP values at 0 minute, 30 minutes, and 12 hours were not significantly different from one another (p > 0.05). No significant correlations were found between treatment failure and age at admission; mean pediatric index of mortality (PIM II), pediatric risk of mortality (PRISM), pediatric logistic organ dysfunction (PELOD) and pediatric multiple organ dysfunction score (P-MODS); and HR, RR, SatO2, pH, PaCO2, PaO2, SBP, DBP, MAP, FiO2 at baseline (p > 0.05). Therapy was successful in 40 (80%) patients whereas there occurred a need for invasive ventilation in 10 (20%) patients. High flow nasal oxygen therapy can be used for patients with acute severe hypoxemic respiratory failure without concurrent hypercapnia when adequate equipment and monitorization tools exist.

The Association between Multisite Near-Infrared Spectroscopy and Routine Hemodynamic Measurements in Relation to Short-Term Outcome in Preterms with Clinical Sepsis

Background: The added clinical value of multisite near-infrared spectroscopy (NIRS) monitoring to detect low organ tissue perfusion in preterm infants at risk of circulatory failure remains unclear. Objectives: To evaluate the associations between multisite NIRS measurements and clinical signs of circulatory failure in relation to short-term outcome in preterm infants with clinical sepsis. Methods: Prospective cohort study of preterm infants (gestational age <32 weeks) with clinical sepsis. We monitored cerebral, renal, and intestinal oxygen saturation using NIRS for 72 h following sepsis workup and calculated fractional tissue oxygen extraction (FTOE). We recorded clinical signs of circulatory failure every 8 h. We analyzed the associations between FTOE values, clinical signs of circulatory failure, and short-term outcome. Results: In 28 preterm infants with clinical sepsis, intraindividual and interindividual associations between NIRS values and clinical signs of circulatory failure were weak. At several points of time during the study period, cerebral and renal FTOE were higher in infants who developed intestinal complications compared with infants who did not, while clinical signs of circulatory failure never differed between groups. After correcting for multiple testing, significant differences disappeared. Conclusions: The associations between multisite FTOE values and clinical signs of circulatory failure were weak in preterm infants with clinical sepsis. Nevertheless, in contrast to clinical signs of circulatory failure, cerebral and renal FTOE values were associated with adverse short-term intestinal outcome in the uncorrected analyses. Multisite NIRS monitoring might help to detect critically low tissue oxygen delivery leading to adverse intestinal outcome not detected by routine hemodynamic measurements.

Borderline hypotension: how does it influence cerebral regional tissue oxygenation in preterm infants?

Aim: To monitor cerebral regional tissue oxygenation (crSO2) of preterm infants continuously and to analyze the influence of arterial hypotension on crSO2. Methods: In this prospective, observational study crSO2, peripheral oxygen saturation (SpO2), heart rate (HR) and mean arterial blood pressure (MABP) were monitored continuously for 24 h, starting within the first 6 h after birth. Furthermore, cerebral fractional tissue oxygen extraction (cFTOE) was calculated. Preterm neonates with and without arterial hypotension (MABP below the gestational age in weeks) were compared to each other. Results: Forty-six preterm infants could be analyzed, 17 with (33.4 ± 1.9 weeks, 2016.5 ± 548.5 g) and 29 without arterial hypotension (33.3 ± 1.3 weeks, 1924.7 ± 451.9 g). Altogether, we detected 30 episodes of hypotension, with a mean duration of 1.6 ± 1.2 h per infant and a mean decrease in MABP of 2.2 ± 0.9 mmHg. During hypotension mean crSO2 was 7 5 ± 11%, 2 h prior to that 76 ± 10% and 2 h after the hypotension 7 7 ± 10%, therefore no significant alterations could be observed. Moreover, there was no significant difference in mean 24-h crSO2, SpO2 and cFTOE between the two groups. Conclusion: Mild short-term hypotensive episodes in preterm infants did not affect crSO2. This suggests that cerebral autoregulation is maintained in case of borderline-hypotension and may protect infants from cerebral injury.

Assessing cerebrovascular autoregulation in infants with necrotizing enterocolitis using near-infrared spectroscopy.

We assessed cerebrovascular autoregulation (CAR) in preterm infants with definite necrotizing enterocolitis (NEC), Bell's stage 2 or 3, and infants without NEC, using near-infrared spectroscopy. We hypothesized that CAR would be more often impaired in infants with NEC compared with infants without NEC. We measured cerebral regional tissue oxygen saturation, arterial oxygen saturation, and mean arterial blood pressure (MABP) during 48 h. We calculated the correlation between cerebral fractional tissue oxygen extraction and MABP for each patient. A statistically significant negative correlation reflected impaired CAR. We included 15 infants with definite NEC (median (range) gestational age 27.4 (25.6-34.7) wk; birth weight 1,070 (670-2,400) g) and 13 infants without NEC (gestational age 27.9 (26.3-34.7) wk; birth weight 980 (640-2,640) g). Fourteen infants had a statistically significant negative correlation (ρ -0.468 to-0.104), of whom five were infants without NEC (5/13; 38%) and nine with definite NEC (9/15; 60%). The difference in prevalence of impaired CAR was not statistically significant. Impaired CAR is present in a substantial proportion of infants with definite NEC, which may predispose them to NEC-associated neurological damage.

Reference Ranges for Cerebral Tissue Oxygen Saturation Index in Term Neonates during Immediate Neonatal Transition after Birth

Background: Non-invasive monitoring of the brain with near-infrared spectroscopy (NIRS) during immediate transition after birth is of growing interest. Objective: The aim of this work was to define reference ranges and centile charts for a regional cerebral tissue oxygenation index (cTOI), measured with the NIRO 200NX (NIRO, Hamamatsu, Japan), and cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 min after birth in preterm and term neonates without any medical support. Methods: cTOI was measured with the NIRO 200NX during the first 15 min after delivery via Caesarean section in preterm and term infants. The NIRS-sensor was placed on the right forehead. Peripheral arterial oxygen saturation (SpO₂) and heart rate were continuously measured by pulse oximetry. cFTOE was calculated out of cTOI and SpO₂. Neonates with a requirement for any medical support were excluded. Results: A total of 230 neonates were enrolled, from which 90 had to be excluded. Therefore, 140 term neonates were included and data were used to define reference ranges and centile charts. The 50th centile (10th to 90th centiles) of cTOI was 56% (39-75) at 2 min, 66% (50-78) at 5 min, 75% (62-85) at 10 min and 73% (61-84) at 15 min after birth. The 50th centile of cFTOE was 0.24 (0.11-0.44) at 2 min, 0.20 (0.10-0.35) at 5 min, 0.21 (0.09-0.35) at 10 min and 0.24 (0.13-0.37) at 15 min after birth. Conclusion: The present observational study adds the reference ranges and centile charts of cTOI measured with the NIRO 200NX and cFTOE calculated out of cTOI and SpO₂ in neonates during the immediate neonatal transition. Centiles for each instrument will be necessary for future clinical application, since the differences between cTOI and cerebral regional tissue oxygen saturation measured with INVOS 5100C change with increasing regional oxygenation.