Changes in cerebral tissue oxygenation and fractional oxygen extraction with gestational age and postnatal maturation in preterm infants

Cerebral tissue oxygen desaturations and increased fractional oxygen extraction events vary by gestational age in preterm infants

BACKGROUND AND OBJECTIVES

Cerebral tissue oxygen saturation (SctO2) and cerebral fractional tissue oxygen extraction (cFTOE) changes with GA in preterm infants. This study examines changes in frequency, duration, and severity of SctO2 desaturation and increased cFTOE with GA.

STUDY DESIGN

The lower limit of normal SctO2, the event threshold, was calculated using a tolerance interval method with 95% confidence interval (CI) and 90% probability. Cerebral desaturation events were defined as: 1) a drop below event threshold for at least 30 s (s), 2) preceded by a period above the event threshold for at least 30s, and 3) followed by a period above the threshold for at least 60s.

RESULTS

86% of infants <28 wk experienced one or more SctO2 desaturation event compared to 57% in >28 wk, odds ratios (OR) 4.5 (CI:1.3-15.3, p = 0.016). The severity of SctO2 desaturation events decreases at a rate of 77.9 units per wk increase in GA (p < 0.001). 39.3% of infants <28 wk experienced one or more increased cFTOE events compared to 28.6% in >28 wk, OR 1.6 (CI:0.6-4.4, p = 0.35). The severity of increasing cFTOE events decreased by 69.7 units per wk increase in GA (p < 0.001).

CONCLUSION

Cerebral tissue oxygen desaturation events decrease in frequency and severity with increasing GA. The severity of increased cFTOE episodes decrease with GA.

Predictors of intracranial hemorrhage in neonatal patients on extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a life-supportive treatment in neonatal patients with refractory lung and/or heart failure. Intracranial hemorrhage (ICH) is a severe complication and reliable predictors are warranted. The aims of this study were to explore the incidence and possible predictors of ICH in ECMO-treated neonatal patients. We performed a single-center retrospective observational cohort study. Patients aged ≤ 28 days treated with ECMO between 2010 and 2018 were included. Exclusion criteria were ICH, ischemic stroke, cerebrovascular malformation before ECMO initiation or detected within 12 h of admission, ECMO treatment < 12 h, or prior treatment with ECMO at another facility > 12 h. The primary outcome was a CT-verified ICH. Logistic regression models were employed to identify possible predictors of the primary outcome. Of the 223 patients included, 29 (13%) developed an ICH during ECMO treatment. Thirty-day mortality was 59% in the ICH group and 16% in the non-ICH group (p < 0.0001). Lower gestational age (p < 0.01, odds ratio (OR) 0.96; 95%CI 0.94-0.98), and higher pre-ECMO lactate levels (p = 0.017, OR 1.1; 95%CI 1.01-1.18) were independently associated with increased risk of ICH-development. In the clinical setting, identification of risk factors and multimodal neuromonitoring could help initiate steps that lower the risk of ICH in these patients.

Preterm infants variability in cerebral near-infrared spectroscopy measurements in the first 72-h after birth

BACKGROUND

Cerebral near-infrared spectroscopy is a non-invasive tool used to measure regional cerebral tissue oxygenation (rScO2) initially validated in adult and pediatric populations. Preterm neonates, vulnerable to neurologic injury, are attractive candidates for NIRS monitoring; however, normative data and the brain regions measured by the current technology have not yet been established for this population.

METHODS

This study's aim was to analyze continuous rScO2 readings within the first 6-72 h after birth in 60 neonates without intracerebral hemorrhage born at ≤1250 g and/or ≤30 weeks' gestational age (GA) to better understand the role of head circumference (HC) and brain regions measured.

RESULTS

Using a standardized brain MRI atlas, we determined that rScO2 in infants with smaller HCs likely measures the ventricular spaces. GA is linearly correlated, and HC is non-linearly correlated, with rScO2 readings. For HC, we infer that rScO2 is lower in infants with smaller HCs due to measuring the ventricular spaces, with values increasing in the smallest HCs as the deep cerebral structures are reached.

CONCLUSION

Clinicians should be aware that in preterm infants with small HCs, rScO2 displayed may reflect readings from the ventricular spaces and deep cerebral tissue.

IMPACT

Clinicians should be aware that in preterm infants with small head circumferences, cerebral near-infrared spectroscopy readings of rScO2 displayed may reflect readings from the ventricular spaces and deep cerebral tissue. This highlights the importance of rigorously re-validating technologies before extrapolating them to different populations. Standard rScO2 trajectories should only be established after determining whether the mathematical models used in NIRS equipment are appropriate in premature infants and the brain region(s) NIRS sensors captures in this population, including the influence of both gestational age and head circumference.

Comparison of the SenSmart™ and the INVOS™ neonatal cerebral near-infrared spectrometry devices

Objectives

To determine the correlation and agreement between the SenSmart™ and the INVOS™ devices of neonatal cerebral regional oxygen saturation (CrSO2) measurements using neonatal sensors. The secondary objective was to develop a regression model that predicts CrSO2-INVOS values using CrSO2-SenSmart indices and determine whether the values between the devices are interchangeable.

Methods

A prospective, cross-sectional study was conducted in infants during the first 4 weeks of life. Simultaneous, bilateral CrSO2 was measured using the SenSmart™X100 (CrSO2-SenSmart) or INVOS™ 5100C (CrSO2-INVOS) device in each frontoparietal area for 2 h. Five-minute CrSO2 values were extracted for analysis.

Results

Thirty infants were recruited with 720 pairwise measurements and 26 (84%) were evaluated in the first week of life. Mean gestational age of the preterm and term infants was [30.9 ± 2.8 (n = 14) and 38.8 ± 1.1 (n = 16)] weeks, respectively. Overall CrSO2- was 77.08 ± 9.70% and 71.45 ± 12.74% for the SenSmart and INVOS, respectively (p < 0.001). The correlation coefficient (r) between the CrSO2-SenSmart and INVOS was 0.20 (p < 0.001). The mean difference between the CrSO2-SenSmart and INVOS was 5.63 ± 13.87% with -21.6% to 32.8% limits of agreement. The r and mean difference was 0.39 (p < 0.001) and 8.87 ± 12.58% in preterm infants, and 0.06 (p = 0.27) and 2.79 ± 14.34 in term infants.

Conclusion

The CrSO2-SenSmart tended to read higher than the CrSO2-INVOS device. There was no correlation between the CrSO2-SenSmart and the CrSO2-INVOS in term infants and it was weak in preterms. Due to imprecise agreement, the CrSO2-SenSmart values are not interchangeable with those of the CrSO2-INVOS.

Early brain and abdominal oxygenation in extremely low birth weight infants

BACKGROUND

Extremely low birth weight (ELBW) infants are at risk for end-organ hypoxia and ischemia. Regional tissue oxygenation of the brain and gut as monitored with near-infrared spectroscopy (NIRS) may change with postnatal age, but normal ranges are not well defined.

METHODS

A prospective study of ELBW preterm infants utilized NIRS monitoring to assess changes in cerebral and mesenteric saturation (Csat and Msat) over the first week after birth. This secondary study of a multicenter trial comparing hemoglobin transfusion thresholds assessed cerebral and mesenteric fractional tissue oxygen extraction (cFTOE and mFTOE) and relationships with perinatal variables.

RESULTS

In 124 infants, both Csat and Msat declined over the first week, with a corresponding increase in oxygen extraction. With lower gestational age, lower birth weight, and 5-min Apgar score ≤5, there was a greater increase in oxygen extraction in the brain compared to the gut. Infants managed with a lower hemoglobin transfusion threshold receiving ≥2 transfusions in the first week had the lowest Csat and highest cFTOE (p < 0.001).

CONCLUSION

Brain oxygen extraction preferentially increased in more immature and anemic preterm infants. NIRS monitoring may enhance understanding of cerebral and mesenteric oxygenation patterns and inform future protective strategies in the preterm ELBW population.

IMPACT

Simultaneous monitoring of cerebral and mesenteric tissue saturation demonstrates the balance of oxygenation between preterm brain and gut and may inform protective strategies. Over the first week, oxygen saturation of the brain and gut declines as oxygen extraction increases. A low hemoglobin transfusion threshold is associated with lower cerebral saturation and higher cerebral oxygen extraction compared to a high hemoglobin transfusion threshold, although this did not translate into clinically relevant differences in the TOP trial primary outcome. Greater oxygen extraction by the brain compared to the gut occurs with lower gestational age, lower birth weight, and 5-min Apgar score ≤5.

Association Analysis of the Cerebral Fractional Tissue Oxygen Extraction (cFTOE) and the Cerebral Oxygen Saturation (crSaO2) with Perinatal Factors in Preterm Neonates: A Single Centre Study

(1) Background: Near-infrared spectroscopy (NIRS) is a non-invasive, easily performed method of monitoring brain oxygenation. The regional cerebral oxygen saturation (crSaO2) and the cerebral fractional tissue oxygen extraction (cFTOE) evaluated by NIRS provide more accurate information on brain oxygenation than the blood oxygen saturation. We investigated the effect of perinatal factors on cerebral oxygenation of preterm newborns. (2) Methods: We conducted a longitudinal study with 48 preterm newborns <34 weeks of gestation who underwent NIRS registration during the first 72 h of life. crSaO2 was measured and cFTOE was calculated foreach patient. (3) Results: One-way ANOVA showed no significant main effect of IVH severity on crSaO2 and cFTOE (p > 0.05); there was a tendency toward statistical significance concerning the difference between the means of crSaO2 (p = 0.083) and cFTOE (p = 0.098). Patients with intraventricular haemorrhage (IVH) had a lower mean of crSaO2 and a higher mean of cFTOE (59.67 ± 10.37% vs. 64.92 ± 10.16% for crSaO2; 0.37 ± 0.11 vs. 0.32 ± 0.11 for cFTOE) compared to those with no IVH. Significantly lower values of crSaO2 and higher values of cFTOE were found in neonates receiving inotropic treatment (p < 0.0001). Episodes of apnoea also proved to influence the cerebral oxygen saturation of the study group (p = 0.0026). No significant association between the maternal hypertension treatment and the cerebral oxygenation of preterms was found. (4) Conclusions: This study showed a decreased cerebral oxygen saturation of preterms with IVH, inotrope support and apnoea episodes.

Fetal Hemoglobin and Tissue Oxygenation Measured With Near-Infrared Spectroscopy-A Systematic Qualitative Review

Fetal hemoglobin (HbF) is a principal oxygen carrier in the blood of preterm and term neonates. Compared to adult hemoglobin, it has a significantly higher affinity for oxygen and its oxyhemoglobin dissociation curve (ODC) is left-shifted accordingly. Tissue oxygenation measured with near-infrared spectroscopy (NIRS) during neonatal intensive care is directly affected by hemoglobin concentration. We performed a systematic qualitative review regarding the impact of HbF on tissue oxygenation monitoring by NIRS. The PubMed/Medline, EMBASE, Cochrane library and CINAHL databases were searched from inception to May 2021 for studies relating to HbF and NIRS in preterm and term neonates in the first days and weeks after birth. Out of 1,429 eligible records, four observational studies were included. Three studies found no effect of HbF on cerebral tissue oxygenation. One peripheral NIRS study found a positive correlation between HbF and peripheral fractional oxygen extraction (FOE). Currently available limited data suggest that FHbF could affect peripheral muscle FOE, but seems not to affect cerebral oxygenation in preterm neonates. More studies are needed to draw a final conclusion on this matter, especially concerning the oxygenation changes driven by adult RBC transfusions.