What Should We Do about Low Blood Pressure in Preterm Infants

Blood volume reduction due to rapid plasma loss after birth in preterm piglets

BACKGROUND

Understanding changes in blood volume after preterm birth is critical to preventing cardiovascular deterioration in preterm infants. The aims were to determine if blood volume is higher in preterm than term piglets and if blood volume changes in the hours after birth.

METHODS

Paired blood volume measurements were conducted in preterm piglets (98/115d gestation, ~28wk gestation infant) at 0.5-5 h (n = 12), 0.5-9 h (n = 44) and 5-11 h (n = 7) after birth, and in a term cohort at 0.5-9 h (n = 40) while under intensive care.

RESULTS

At 30 min after birth, blood volume was significantly lower in preterm piglets compared to term piglets. By 9 h after birth, blood volume had reduced by 18% in preterm piglets and 13% in term piglets. By 5-9 h after birth, preterm piglets had significantly lower blood volumes than at term (61 ± 10 vs. 76 ± 11 mL/kg).

CONCLUSIONS

In contrast to clinical resources, preterm piglets have a lower blood volume than at term. Substantial reductions in blood volume after birth leave some preterm piglets hypovolemic. If this also occurs in preterm infants, this may have important clinical consequences. Modern studies of blood volume changes after birth are essential for improving preterm outcomes.

IMPACT

Preterm piglets do not have a higher blood volume than their term counterparts, in contrast to current clinical estimates. Rapid reduction in blood volume after birth leads to hypovolemia in some preterm piglets. There is a critical need to understand blood volume changes after birth in preterm infants in order to improve clinical management of blood volume.

Neonatal blood pressure by birth weight, gestational age, and postnatal age: a systematic review

BACKGROUND

Blood pressure is a vital hemodynamic marker during the neonatal period. However, normative values are often derived from small observational studies. Understanding the normative range would help to identify ideal thresholds for intervention to treat hypotension or hypertension. Therefore, the aim of this study was to assess observed blood pressure values in neonates who have not received any blood-pressure modifying treatments from birth to three months postnatal age and whether these vary according to birth weight, gestational age and postnatal age.

METHODS

This was a systematic review. A literature search was conducted in MEDLINE, PubMed, Embase, Cochrane Library, and CINAHL from 1946 to 2017 on blood pressure in neonates from birth to 3 months of age (PROSPERO ID CRD42018092886). Unpublished data were included where appropriate.

RESULTS

Of 3,587 non-duplicate publications identified, 30 were included (one unpublished study). Twelve studies contained data grouped by birth weight, while 23 contained data grouped by gestational age. Study and clinical heterogeneity precluded meta-analyses thus results are presented by subgroup. A consistent blood pressure rise was associated with increasing birth weight, gestational age, and postnatal age. In addition, blood pressure seemed to rise more rapidly in the most preterm and low birth weight neonates.

CONCLUSION

Despite blood pressure increasing with birth weight, gestational age, and postnatal age, there was marked blood pressure variability observed throughout. To better define hypotension and hypertension, future studies should develop consistent approaches for factors related to blood pressure variability, including the method and timing of measurement as well as statistical control of relevant patient characteristics.

Use of Vasopressin as Rescue Therapy in Refractory Hypoxia and Refractory Systemic Hypotension in Term Neonates with Severe Persistent Pulmonary Hypertension-A Prospective Observational Study

OBJECTIVE

 Persistent pulmonary hypertension of the newborn (PPHN) is a serious cardiorespiratory problem. PPHN is frequently associated with refractory hypoxia and hypotension, and optimal management has the potential to improve important clinical outcomes including mortality. The primary objective is to evaluate the efficacy and safety of rescue vasopressin (VP) therapy in the management of severe (refractory) hypoxia and refractory systemic hypotension in term neonates with severe PPHN.

STUDY DESIGN

 Neonates with refractory hypoxia and refractory hypotension due to severe PPHN needing VP were prospectively enrolled in the study. Refractory hypoxia was defined as oxygenation index (OI) ≥ 25 for at least 4 hours after the commencement of high-frequency oscillatory ventilation and nitric oxide at 20 ppm. Refractory hypotension was defined as mean blood pressure lesser than mean gestational age lasting for more than 15 minutes in spite of dopamine infusion at 10 µg/kg/min, adrenaline infusion at 0.3 µg/kg/min, and noradrenaline infusion at 0.1 µg/kg/min.

RESULTS

 Thirty-two neonates with PPHN were recruited. The baseline OI (mean ± standard deviation [SD]) before starting VP was 33.43 ± 16.54 which started decreasing significantly between 1 and 6 hours after the commencement of VP (p < 0.05). The mean blood pressure also increased concomitantly with a significant effect seen by 1 hour (p < 0.05). The vasoactive infusion score before the commencement of VP was mean 46.07 (SD = 25.72) and started decreasing after 12 to 24 hours of commencement of VP (p < 0.05). Lactate levels (mean ± SD) before starting VP were 7.8 ± 8.6 mmol/L and started decreasing between 6 and 12 hours (p < 0.05). Two neonates died due to refractory hypoxia and refractory hypotension (overall mortality 6.2%) CONCLUSION:  Rescue VP therapy is a useful adjunct in the management of neonates with severe PPHN with refractory hypoxia and/or refractory hypotension. Improvement in oxygenation and hemodynamics with the use of VP results in reduced mortality.

KEY POINTS

· Rescue vasopressin is a useful adjunct in the management of neonates with severe PPHN.. · Vasopressin helps reduce OI.. · Vasopressin reduces the vasoactive inotrope score..

An Update on Pharmacologic Management of Neonatal Hypotension: When, Why, and Which Medication

Anti-hypotensive treatment, which includes dopamine, dobutamine, epinephrine, norepinephrine, milrinone, vasopressin, terlipressin, levosimendan, and glucocorticoids, is a long-established intervention in neonates with arterial hypotension (AH). However, there are still gaps in knowledge and issues that need clarification. The main questions and challenges that neonatologists face relate to the reference ranges of arterial blood pressure in presumably healthy neonates in relation to gestational and postnatal age; the arterial blood pressure level that potentially affects perfusion of critical organs; the incorporation of targeted echocardiography and near-infrared spectroscopy for assessing heart function and cerebral perfusion in clinical practice; the indication, timing, and choice of medication for each individual patient; the limited randomized clinical trials in neonates with sometimes conflicting results; and the sparse data regarding the potential effect of early hypotension or anti-hypotensive medications on long-term neurodevelopment. In this review, after a short review of AH definitions used in neonates and existing data on pathophysiology of AH, we discuss currently available data on pharmacokinetic and hemodynamic effects, as well as the effectiveness and safety of anti-hypotensive medications in neonates. In addition, data on the comparisons between anti-hypotensive medications and current suggestions for the main indications of each medication are discussed.

Corticosteroid use in neonatal hypotension: A survey of Canadian neonatologists

OBJECTIVE

To assess prescribing practices and perspectives regarding the use of corticosteroids in the management of neonatal hypotension.

METHODS

Cross-sectional questionnaire-based electronic survey of neonatologists (n = 206) practicing at tertiary neonatal intensive care units across 30 academic centres in Canada.

RESULTS

The overall response rate was 33% (72/206), with a completion rate was 94%. Most (48/72, 64%) worked in a unit that covered both inborn and outborn infants, and 53% (37/70) worked in units with >100 very low birth weight infants admitted annually. Among the 72 respondents, 39% use a loading dose, of whom most (57%) use 2 mg/kg. Dosing ranges were variable, most using either 0.5 mg/kg or 1 mg/kg, q6h. Among the 56% (40/72) of neonatologists who reported measuring cortisol before initiation of hydrocortisone, cut-offs for initiation of hydrocortisone varied from <100 to <500 nmol/L, most of whom (48%) used <100 nmol/L. Of 71 respondents, 92% (65) indicated that a randomized control trial examining the use of corticosteroids in neonatal hypotension is needed, of whom 52% (37) indicated that the intervention group should receiving hydrocortisone after one vasopressor/inotrope.

CONCLUSIONS

This survey provides insight into the prescribing practices of tertiary neonatologists with regards to the use of corticosteroids in neonatal hypotension. While corticosteroids are frequently prescribed, there is variability in the indication, dosing, and duration of corticosteroid use. The findings from this survey can be used to inform further research, including a clinical trial, regarding the practice in the management of neonatal hypotension.

Towards Non-Invasive and Continuous Blood Pressure Monitoring in Neonatal Intensive Care Using Artificial Intelligence: A Narrative Review

Preterm birth is a live birth that occurs before 37 completed weeks of pregnancy. Approximately 11% of babies are born preterm annually worldwide. Blood pressure (BP) monitoring is essential for managing the haemodynamic stability of preterm infants and impacts outcomes. However, current methods have many limitations associated, including invasive measurement, inaccuracies, and infection risk. In this narrative review, we find that artificial intelligence (AI) is a promising tool for the continuous measurement of BP in a neonatal cohort, based on data obtained from non-invasive sensors. Our findings highlight key sensing technologies, AI techniques, and model assessment metrics for BP sensing in the neonatal cohort. Moreover, our findings show that non-invasive BP monitoring leveraging AI has shown promise in adult cohorts but has not been broadly explored for neonatal cohorts. We conclude that there is a significant research opportunity in developing an innovative approach to provide a non-invasive alternative to existing continuous BP monitoring methods, which has the potential to improve outcomes for premature babies.

A Reduction in Antenatal Steroid Dose Was Associated with Reduced Cardiac Dysfunction in a Sheep Model of Pregnancy

Despite widespread use, dosing regimens for antenatal corticosteroid (ACS) therapy are poorly unoptimized. ACS therapy exerts a programming effect on fetal development, which may be associated with an increased risk of cardiovascular disease. Having demonstrated that low-dose steroid therapy is an efficacious means of maturing the preterm lung, we hypothesized that a low-dose steroid exposure would exert fewer adverse functional and transcriptional changes on the fetal heart. We tested this hypothesis using low-dose steroid therapy (10 mg delivered to the ewe over 36 h via constant infusion) and compared cardiac effects with those of a higher dose treatment (30 mg delivered to the ewe over 24 h by intramuscular injection; simulating currently employed clinical ACS regimens). Fetal cardiac function was assessed by ultrasound on the day of ACS treatment initiation. Transcriptomic analyses were performed on fetal myocardial tissue. Relative to saline control, fetuses in the higher-dose clinical treatment group had significantly lower ratios between early diastolic ventricular filling and ventricular filling during atrial systole, and showed the differential expression of myocardial hypertrophy-associated transcripts including βMHC, GADD45γ, and PPARγ. The long-term implications of these changes remain unstudied. Irrespective, optimizing ACS dosing regimens to maximize respiratory benefit while minimizing adverse effects on key organ systems, such as the heart, offers a means of improving the acute and long-term outcomes associated with this important obstetric therapy.

[Risk factors and prognosis of hypotension within 72 hours after birth in extremely preterm infants]

OBJECTIVES

To investigate the risk factors and prognosis of hypotension within 72 hours after birth in extremely preterm infants.

METHODS

A retrospective analysis was conducted on clinical data of extremely preterm infants admitted to the Children's Hospital of Zhejiang University School of Medicine from January 2019 to April 2022. Based on the presence of hypotension within 72 hours after birth, the eligible infants were divided into a hypotension group (41 cases) and a normotension group (82 cases). The clinical characteristics, echocardiographic parameters within 72 hours after birth, and early complications were compared between the two groups. Multivariate logistic regression analysis was used to explore the risk factors for hypotension within 72 hours after birth, and receiver operating characteristic curve analysis was performed to evaluate the predictive value of relevant indicators for the occurrence of hypotension within 72 hours after birth in the preterm infants.

RESULTS

The proportion of infants who required medication or surgical closure of patent ductus arteriosus (PDA), the proportions of infants with intraventricular hemorrhage ≥ grade III and severe pulmonary hemorrhage, and the mortality rate within 7 days in the hypotension group were significantly higher than those in the normotension group (P<0.05). Multivariate logistic regression analysis showed that lower birth weight, larger PDA diameter, and hemodynamically significant PDA were risk factors for the occurrence of hypotension within 72 hours after birth in extremely preterm infants (P<0.05). The receiver operating characteristic curve analysis showed that the combination of birth weight, PDA diameter, and hemodynamically significant PDA had an area under the curve of 0.873 (95%CI: 0.802-0.944, P<0.05) for predicting hypotension within 72 hours after birth, with a sensitivity of 73.2% and specificity of 91.5%.

CONCLUSIONS

Hypotension within 72 hours after birth is closely related to birth weight and PDA, and increases the risk of early severe complications and mortality in extremely preterm infants.

Insights into Neonatal Cerebral Autoregulation by Blood Pressure Monitoring and Cerebral Tissue Oxygenation: A Qualitative Systematic Review

OBJECTIVE

The aim of this qualitative systematic review was to identify publications on blood pressure monitoring in combination with cerebral tissue oxygenation monitoring during the first week after birth focusing on cerebral autoregulation.

METHODS

A systematic search was performed on PubMed. The following search terms were used: infants/newborn/neonates, blood pressure/systolic/diastolic/mean/MAP/SAP/DAP, near-infrared spectroscopy, oxygenation/saturation/oxygen, and brain/cerebral. Additional studies were identified by a manual search of references in the retrieved studies and reviews. Only human studies were included.

RESULTS

Thirty-one studies focused on preterm neonates, while five included preterm and term neonates. In stable term neonates, intact cerebral autoregulation was shown by combining cerebral tissue oxygenation and blood pressure during immediate transition, while impaired autoregulation was observed in preterm neonates with respiratory support. Within the first 24 h, stable preterm neonates had reduced cerebral tissue oxygenation with intact cerebral autoregulation, while sick neonates showed a higher prevalence of impaired autoregulation. Further cardio-circulatory treatment had a limited effect on cerebral autoregulation. Impaired autoregulation, with dependency on blood pressure and cerebral tissue oxygenation, increased the risk of intraventricular hemorrhage and abnormal neurodevelopmental outcomes.

CONCLUSIONS

Integrating blood pressure monitoring with cerebral tissue oxygenation measurements has the potential to improve treatment decisions and optimizes neurodevelopmental outcomes in high-risk neonates.

[Influence of hypotension on the short-term prognosis of preterm infants with a gestational age of <32 weeks]

OBJECTIVES

To investigate the influence of early-stage hypotension defined as mean arterial pressure (MAP)<gestational age (weeks) or MAP<30 mmHg on the short-term prognosis of preterm infants with a gestational age of <32 weeks.

METHODS

A total of 320 preterm infants who were admitted to Maternal and Child Health Hospital of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology from April 2020 to August 2021 and met the inclusion criteria were enrolled in this prospective study. Blood pressure within 72 hours was monitored. The definition of hypotension and grouping were as follows: (1) Of the 320 preterm infants, those with MAP<gestational age in 2 consecutive measurements served as the hypotension group (n=104), and the others (n=216) served as the control group; (2) Of the 320 preterm infants, those with MAP<30 mmHg in 2 consecutive measurements served as the hypotension group (n=114), and the others served as the control group (n=206). Perinatal data and clinical data during hospitalization were collected.Poor short-term prognosis was defined as death during hospitalization and/or grade Ⅲ-Ⅳ periventricular-intraventricular hemorrhage identified within 1 week after birth. The multivariate logistic regression analysis was used to investigate the influence of hypotension based on the above two definitions on the short-term prognosis of preterm infants.

RESULTS

Compared with the control group, the hypotension group based on the above two definitions had higher incidence rates of the clinical manifestations of hypoperfusion, poor prognosis, hemodynamically significant patent ductus arteriosus, and pulmonary hemorrhage (P<0.05). In addition, compared with the control group, the hypotension group defined by MAP<30 mmHg had higher incidence rates of periventricular-intraventricular hemorrhage and bronchopulmonary dysplasia and mortality rate during hospitalization (P<0.05). The incidence of poor short-term prognosis in the hypotension group defined by MAP<30 mmHg was higher than that in the hypotension group defined by MAP<gestational age (18.4% vs 12.5%), but the difference was not statistically significant (P>0.05).The univariate analysis showed that the poor short-term prognosis was related to birth of cesarean section, gestational age, an Apgar score of ≤ 5 at 5 minutes, use of vasoactive drugs within 72 hours, mechanical ventilation within 72 hours, and hypotension under the two definitions (P<0.05).The multivariate logistic regression showed that hypotension based on either definition was not an independent risk factor for poor prognosis (P>0.05).

CONCLUSIONS

Hypotension based on either definition is not an independent risk factor for short-term poor prognosis in preterm infants with a gestational age of <32 weeks. Hypotension defined by MAP<30 mmHg might be more sensitive than that defined by MAP<gestational age in predicting short-term adverse outcomes, which needs further analysis by large sample studies.

Vasoactive inotropic score as a predictor of mortality in neonatal septic shock

BACKGROUND

Although many improvements in neonatal care have been achieved, mortality rates for sepsis and septic shock in newborns are still high. The vasoactive inotropic score (VIS) was designed and studied to predict mortality in different settings. There are currently no data on the predictive ability of the VIS for mortality in newborn patients with septic shock.

METHODS

Patients with late-onset neonatal sepsis who required inotropes because of fluid-refractory septic shock during the study period were included in the study. Four distinct VIS values were calculated for each septic shock episode after inotropic treatment had begun, that is, at the initiation of inotropic treatment and at 24 and 48 h after inotropic treatment had begun, and the highest VIS (VISmax) at any time after initiation of inotropic agents.

RESULTS

The 98 episodes studied were divided into two groups according to the outcomes of their sepsis episodes as survivors (n = 39) or nonsurvivors (n = 59). The areas under the curve of the VIS values for the prediction of mortality were the VISmax (0.819, p < 0.001), followed by the VIS48 (0.802, p < 0.001), VIS24 (0.762, p = 0.001) and VIS0 (0.699, p = 0.015). Patients with a VISmax of greater than 20 had significantly higher odds of mortality (p < 0.001, β = 14.7, 95% confidence interval [4.7-45.9]).

CONCLUSION

We found that the VISmax was an easy-to-use and helpful tool for predicting a poor outcome in neonatal sepsis. Physicians should be aware that the prognosis is poor for any newborn with a VIS of 20 or greater at any point after the onset of sepsis.

Recognition and Management of Cardiovascular Insufficiency in the Very Low Birth Weight Newborn

The measurement of blood pressure in the very low birth weight newborn infant is not simple and may be erroneous because of numerous factors. Assessment of cardiovascular insufficiency in this population should be based on multiple parameters and not only on numeric blood pressure readings. The decision to treat cardiovascular insufficiency should be made after considering the potential complications of such treatment. There are numerous potential strategies to avoid or mitigate hypoperfusion states in the very low birth weight infant.

Antenatal Betamethasone Every 12 Hours in Imminent Preterm Labour

Background: Benefits of antenatal corticosteroids have been established for preterm infants who have received the full course. In imminent preterm labours there is no time to administer the second dose 24 h later. Objective: To determine whether the administration of two doses of betamethasone in a 12 h interval is equivalent to the effects of a full maturation. Methods: We performed a retrospective cohort study including preterm infants ≤34 weeks gestational age at birth and ≤1500 g, admitted to an NICU IIIC level in a tertiary hospital from 2015 to 2020. The population was divided into two cohorts: complete maturation (CM) (two doses of betamethasone 24 h apart), or advanced maturation (AM) (two doses of betamethasone 12 h apart). The primary outcomes were mortality or survival with severe morbidities. The presence of respiratory distress syndrome and other morbidities of prematurity were determined. These variables were analysed in the neonates under 28 weeks gestational age cohort. Neurodevelopment at 2 years was evaluated with the validated Ages and Stages Questionnaires^®, Third Edition (ASQ^®-3). Multiple regression analyses were performed and adjusted for confounding factors. Results: A total of 275 preterm neonates were included. Serious outcomes did not show differences between cohorts, no increased incidence of morbidity was found in AM. A lower percentage of hypotension during the first week (p = 0.04), a tendency towards lower maximum FiO₂ (p = 0.14) and to a shorter mechanical ventilation time (p = 0.14) were observed for the AM cohort. Similar results were found in the subgroup of neonates under 28 weeks gestational age. There were no differences in cerebral palsy or sensory deficits at 24 months of corrected age, although the AM cohort showed a trend towards better scores on the ASQ3 scale. Conclusions: Administration of betamethasone every 12 h showed similar results to the traditional pattern with respect to mortality and severe morbidities. No deleterious neurodevelopmental effects were found at 24 months of corrected age. Earlier administration of betamethasone at 12 h after the first dose would be an alternative in imminent preterm delivery. Further studies are needed to confirm these results.

Expression of TRPM6 and TRPM7 in the preterm piglet heart

Preterm infants are at increased risk of death and disability, and cardiovascular instability after birth is a contributing factor. Immaturity of calcium handling in the preterm heart may limit myocardial contractility and cardiac output. Two transmembrane cation channels, TRPM6 and TRPM7, may regulate intracellular cardiac calcium in the neonatal period. The aim of this study was to determine TRPM6 and TRPM7 mRNA expression in piglet hearts in late gestation, and the effects of sex, maternal glucocorticoids, and the transition to extrauterine life. Left and right ventricular tissue was collected at a range of gestational ages from cesarean delivered piglets at birth and at 6 h old. Additional groups included piglets exposed to maternal glucocorticoid treatment and spontaneously born term piglets at 12-24 h old. TRPM6 and TRPM7 mRNA expression was measured using RT-qPCR. Males had significantly lower TRPM7 expression in the left ventricle across all gestational ages compared to females. At term, both ventricles had higher TRPM7 expression at 6 h old than at birth. In preterm piglets, TRPM7 expression only increased postnatally in the right ventricle following maternal glucocorticoid exposure. At 12-24 h old, TRPM7 expression in both ventricles was lower than levels in 6 h old term Caesar piglets (113 days). Male preterm piglets may have immature myocardial Ca²⁺ handling and this could contribute to their poorer outcomes. Increased TRPM7 expression is the mature response to birth that is missing in preterm neonates. TRPM7 could serve as a novel target to improve cardiac function in preterm neonates.

Safety and efficacy of a novel double-lumen tracheal tube in neonates with RDS: A prospective cohort study

BACKGROUND

The purpose of this study was to assess the safety and efficacy of a new double-lumen tracheal tube for neonates, with a conventional tracheal tube as a control.

METHOD

Newborns with respiratory distress syndrome (RDS) requiring endotracheal intubation admitted to the tertiary neonatal intensive care unit (NICU) of Qujing Maternal and Child Healthcare Hospital in Yunnan Province between March 2021 and May 2022 were enrolled in this prospective cohort study. Outcome indicators related to effectiveness included mainly the number of intubations, duration of ventilation, duration of oxygenation, and length of stay; safety indicators included any clinical adverse effects during and after intubation. Appropriate stratified and subgroup analyses were performed according to the purpose of intubation, gestational age, and whether the drug was administered via endotracheal tube.

RESULT

A total of 101 neonates were included and divided into two groups based on the choice of tracheal tube: the conventional (n = 50) and new (n = 51) tracheal tube groups. There was no statistical difference between the two groups in terms of adverse effects during and after intubation (p > 0.05). In neonates who were mechanically ventilated without endotracheal surfactant therapy or newborns receiving InSurE technique followed by non-invasive ventilation, no significant differences were found between the two groups regarding any of the efficacy indicators (p > 0.05). However, for neonates on invasive mechanical ventilation, the new tracheal tube allowed for a significant reduction in the duration of mechanical ventilation (96.50[74.00, 144.00] vs. 121.00[96.00, 196.50] hours, p = 0.037) and total ventilation (205.71 ± 80.24 vs. 277.56 ± 117.84 h, p = 0.027), when used as a route for endotracheal drug delivery. Further analysis was performed according to gestational age for newborns requiring intratracheal surfactant administration during mechanical ventilation, and the data showed that for preterm infants, the new tracheal tube not only shortened the duration of mechanical ventilation (101.75 ± 39.72 vs. 155.50 ± 51.49 h, p = 0.026) and total ventilation (216.00 ± 81.60 vs. 351.50 ± 113.79 h, p = 0.010), but also demonstrated significant advantages in reducing the duration of oxygen therapy (9.75 ± 6.02 vs. 17.33 ± 8.43 days, p = 0.042); however, there was no statistical difference in efficacy outcomes between the two groups in full-term infants (p > 0.05).

CONCLUSION

The efficacy and safety of this new tracheal tube are promising in neonates with RDS, especially those requiring surfactant administration via a tracheal tube during mechanical ventilation. Given the limitations of this study, however, the clinical feasibility of this catheter needs to be further confirmed in prospective randomized trials with larger sample sizes.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/showproj.aspx?proj=122073.

Correlation between arterial blood pressures and regional cerebral oxygen saturation in preterm neonates during postnatal transition-an observational study

OBJECTIVE

To assess whether blood pressure (systolic (SABP), diastolic (DABP), and mean arterial blood pressure (MABP) and cerebral-regional-oxygen-saturation (crSO2) and cerebral-fractional-tissue-oxygen-extraction (cFTOE) are associated after immediate fetal-to-neonatal transition in preterm neonates with and without respiratory support.

STUDY DESIGN

Post-hoc analyses of secondary outcome parameters of prospective observational studies were performed. We included moderate and late preterm neonates with and without respiratory support with cerebral NIRS monitoring (INVOS 5100c) and an oscillometric blood pressure measurement at minute 15 after birth. Heart rate (HR) and arterial oxygen saturation (SpO2) were monitored routinely. Blood pressure values were correlated with crSO2 and cFTOE.

RESULTS

47 preterm neonates with NIRS measurements and blood pressure measurement during immediate transition after birth were included. Twenty-five preterm neonates (gestational age: 34.4±1.6 weeks) received respiratory support. In these neonates crSO2 correlated significantly positively with systolic blood pressure (SABP; r = 0.46, p = 0.021), diastolic blood pressure (DABP; r = 0.51, p = 0.009) and, mean arterial pressure (MABP; r = 0.48, p = 0.015). cFTOE correlated significantly negatively with SABP (r = -0.44, p = 0.027), DABP (r = -0.49, p = 0.013) and mean MABP (r = -0.44, p = 0.029). Twenty-two preterm neonates (gestational age: 34.5 ± 1.5 weeks) did not receive respiratory support. In those neonates, neither crSO2 nor cFTOE correlated with blood pressure.

CONCLUSION

In compromised moderate and late preterm neonates with respiratory support, both, crSO2 and cFTOE correlated with blood pressure. These findings suggest that passive pressure-dependent cerebral perfusion was present in preterm neonates with respiratory support, indicating an impaired cerebral autoregulation in those compromised preterm neonates.

Physiology of Low Blood Pressure During the First Day After Birth Among Extremely Preterm Neonates

OBJECTIVE

To investigate the circulatory physiology of hypotension during the first day after birth among stable extremely preterm neonates.

STUDY DESIGN

Case-control study of neonates born at ≤27^6/7 weeks gestational age with hypotension, defined as mean blood pressure in mmHg less than gestational age in weeks for at least 1 hour during the first 24 hours after birth, who underwent comprehensive echocardiography assessment before commencement of cardiovascular drugs. Neonates with hypotension (n = 14) were matched by gestational age and intensity of respiratory support with normotensive neonates (n = 27) who underwent serial echocardiography during the first day after birth, and relatively contemporaneous echocardiography assessments were used for comparison.

RESULTS

Neonates with hypotension had a higher frequency of patent ductus arteriosus ≥1.5 mm (71% vs 15%; P < .001) and ductal size (median diameter, 1.6 mm [IQR, 1.4-2.1] vs 1.0 mm [IQR, 0-1.3]; P = .002), higher echocardiography indices of left ventricular systolic function (mean shortening fraction, 34 ± 7% vs 26 ± 4%; P < .001; mean longitudinal strain, -16 ± 5% vs -14 ± 3%; P = .04; and mean velocity of circumferential fiber shortening, 1.24 ± 0.35 circ/s vs 1.01 ± 0.28 circ/s; P = .03), lower estimates of left ventricular afterload (mean end-systolic wall stress, 20 ± 7 g/cm² vs 30 ± 9 g/cm²; P < .001 and mean arterial elastance, 43 ± 19 mmHg/mL vs 60 ± 22 mmHg/mL; P = .01), without significant difference in stress-velocity index z-score (-0.42 ± 1.60 vs -0.88 ± 1.30; P = .33). Neonates with hypotension had higher rates of any degree of intraventricular hemorrhage (71% vs 22%; P = .006).

CONCLUSIONS

Low blood pressure in otherwise well extremely low gestational age neonates was associated with low systemic afterload and larger patent ductus arteriosus, but not left ventricular dysfunction.

Functional echocardiographic preload markers in neonatal septic shock

BACKGROUND

There are no established clinical or laboratory markers of preload adequacy and fluid responsiveness in management of neonatal shock. Functional echocardiographic preload markers are evaluated in children and adults, but there is no data in neonatal septic shock. We evaluated five functional echocardiographic preload markers during intravenous volume resuscitation in neonatal septic shock.

OBJECTIVE

(1) To compare baseline functional echocardiographic preload markers between neonates with septic shock and their "matched" healthy controls. (2) To compare echocardiographic preload markers before and after intravenous volume resuscitation.

METHODS

In this cohort study, we enrolled neonates with septic shock (cases) and recorded five preload markers - inferior vena cava collapsibility index (IVC-CI), left ventricular end-diastolic (LVEDV) & end-systolic volume (LVESV) and their indices (LVEDVI, LVESVI) - before initiation of intravenous fluid resuscitation (baseline evaluation). An equal number of "matched hemodynamically stable" controls were recruited, who underwent functional echocardiographic assessment once. In neonates with shock, we recorded these markers again after volume resuscitation.

RESULTS

We analyzed 46 neonates (23 cases and 23 controls). Neonates with shock had significantly elevated baseline IVC-CI as compared to controls [53% (21, 100) vs. 20% (15, 24) respectively, p-value = .01). Rest 4 echocardiographic markers (LVEDV, LVESV, LVEDVI, and LVESVI) were comparable between cases and controls. Sixteen neonates (70% of 23) received intravenous fluid resuscitation and rest 7 (30%) were started directly on vasoactive drugs. None of the preload markers changed significantly after volume resuscitation as compared to the baseline values including IVC-CI, which was almost significant [74% (33, 100) at baseline to 48% (13, 93) after 10 mL/kg and 50% (40, 69) after 20 mL/kg, (p = .05). All preload markers were comparable between survivors and non-survivors.

CONCLUSION

Neonates with septic shock had significantly elevated IVC-CI at baseline as compared to hemodynamically stable neonates. None of the preload markers changed significantly after volume resuscitation as compared to the baseline values including IVC-CI, which was almost significant.

Cardiovascular Pharmacological Support Among Preterm Infants in Chinese Referral Center Neonatal Intensive Care Units

Objective: To describe cardiovascular pharmacological support in infants born at <34 weeks' gestation within the first postnatal week in Chinese neonatal intensive care units (NICUs). Design: A secondary analysis of data from a multicenter randomized controlled study (REIN-EPIQ). A questionnaire regarding cardiovascular support practices was also completed by all participating NICUs. Setting: Twenty-five tertiary hospitals from 19 provinces in China. Patients: All infants born at <34 weeks' gestation and admitted to participating NICUs within the first postnatal week from May 2015 to April 2018 were included. Infants who were discharged against medical advice were excluded. Measures and Main Results: Among the 26,212 preterm infants <34 weeks, 16.1% received cardiovascular pharmacological support. The use rates increased with decreasing gestational age and birth weight, with 32.5% among infants <28 weeks and 35.9% among infants <1,000 g. Cardiovascular pharmacological support was independently associated with higher risks of death (aOR 2.8; 95% CI 2.4-3.3), severe intraventricular hemorrhage (IVH) (aOR 2.1; 95% CI 1.8-2.5) and bronchopulmonary dysplasia (BPD) (aOR 2.2; 95% CI 2.0-2.5). Overall 63.1% courses of cardiovascular pharmacological support were >3 days. Prolonged cardiovascular pharmacological support (>3 days) was independently associated with lower rates of survival without morbidity in very-low-birth-weight infants, compared with infants with shorter durations. Dopamine was the most commonly used cardiovascular agent. The cardiovascular pharmacological support rates varied from 1.9 to 65.8% among the participating NICUs. Conclusions: The rate of cardiovascular pharmacological support within the first postnatal week was high with prolonged durations in Chinese NICUs. Marked variation in cardiovascular support existed among participating NICUs. Cardiovascular pharmacological support during the early postnatal period, especially prolonged, may be associated with adverse neonatal outcomes. Clinical Trial Registration: The original trial was registered as "Reduction of Infection in Neonatal Intensive Care Units using the Evidence-based Practice for Improving Quality" (ID: NCT02600195) on clinicaltrials.gov. https://clinicaltrials.gov/ct2/show/NCT02600195?term=NCT02600195&draw=2&rank=1.

Propofol in neonates causes a dose-dependent profound and protracted decrease in blood pressure

AIM

To analyse the effects of different propofol starting doses as premedication for endotracheal intubation on blood pressure in neonates.

METHODS

Neonates who received propofol starting doses of 1.0 mg/kg (n = 30), 1.5 mg/kg (n = 23) or 2.0 mg/kg (n = 26) as part of a previously published dose-finding study were included in this analysis. Blood pressure in the 3 dosing groups was analysed in the first 60 minutes after start of propofol.

RESULTS

Blood pressure declined after the start of propofol in all 3 dosing groups and was not restored 60 minutes after the start of propofol. The decline in blood pressure was highest in the 2.0 mg/kg dosing group. Blood pressure decline was mainly dependent on the initial propofol starting dose rather than the cumulative propofol dose.

CONCLUSION

Propofol causes a dose-dependent profound and prolonged decrease in blood pressure. The use of propofol should be carefully considered. When using propofol, starting with a low dose and titrating according to sedative effect seems the safest strategy.

Relationships between antenatal corticosteroids and catecholamine blood pressure support in neonates: considering of maternal stress-related diseases

Healthy child development is under the influence of prenatal and perinatal exposure to stress stimuli. The aim of this study is to test the hypotheses that (1) neonates requiring catecholamine blood pressure support are more often born to mothers with stress-related cardiometabolic diseases, (2) maternal stress-related diseases are associated with more frequent requirement of maternal corticosteroid treatment and (3) antenatal steroid exposure of neonates reduces the need of postnatal catecholamine support. A retrospective cohort study was performed on a sample of 427 mature (13%), preterm (64%) and extremely preterm (23%) neonates of both sexes. Mothers at risk of preterm delivery were treated with dexamethasone. The blood pressure support in neonates was performed by intravenous treatment via umbilical or epicutaneous venous catheter with dopamine (5 ug/kg/min) or dobutamine (5 ug/kg/min) or a combination of both. The results showed a lack of association between maternal stress-related diseases and the complicated outcome of their neonates. Maternal treatment with corticosteroid dexamethasone was associated with lower frequency of catecholamine blood pressure support requirement. Catecholamine support was more needed in male infants. Thus, the occurrence of maternal cardiometabolic stress-related diseases does not appear to be related to the need of catecholamine support in the neonate. In agreement with the second hypothesis, a more frequent maternal corticosteroid treatment was associated with the presence of maternal stress-related diseases. Most importantly, the obtained results support the hypothesis on positive influence of maternal glucocorticoid administration on cardiovascular outcome of the neonate, representing an additional beneficial effect of antenatal corticosteroids. LAY SUMMARY Maternal hypertension, diabetes and obesity, which belong to cardiometabolic stress-related diseases, failed to show a negative influence on neonatal health as was determined by the need of catecholamine blood pressure support in a large sample of 427 immature and mature newborns. Since glucocorticoids are often viewed as negative agents that should be avoided, the important finding of the present study is the beneficial effect of maternal corticosteroid treatment on blood pressure stability of the neonate.

Machine Learning to Support Hemodynamic Intervention in the Neonatal Intensive Care Unit

Hemodynamic support in neonatal intensive care is directed at maintaining cardiovascular wellbeing. At present, monitoring of vital signs plays an essential role in augmenting care in a reactive manner. By applying machine learning techniques, a model can be trained to learn patterns in time series data, allowing the detection of adverse outcomes before they become clinically apparent. In this review we provide an overview of the different machine learning techniques that have been used to develop models in hemodynamic care for newborn infants. We focus on their potential benefits, research pitfalls, and challenges related to their implementation in clinical care.

Neonatal Blood Pressure Standards: What Is "Normal"?

Blood pressure (BP) is routinely measured in newborn infants. Published BP nomograms demonstrate a rise in BP following delivery in healthy infants at all gestational ages (GA) and evidence that BP values are higher with increasing birth weight and GA. However, the complex physiology that occurs in newborn infants and range of BP values observed at all GA make it difficult to identify "normal" BP for a specific infant at a specific time under specific conditions. As such, complete hemodynamic assessment should include the physical examination, perinatal history, other vital signs, and laboratory values in addition to BP values.

Antioxidant alterations link polycyclic aromatic hydrocarbons to blood pressure in children

Exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with changes in blood pressure. However, the association is controversial in different studies, and antioxidants' roles involved in it remain unclear. To investigate the associations among PAH exposure, blood pressure, and antioxidant concentrations, we recruited 403 children (2-7 years old), of which 203 were from Guiyu, an e-waste-recycling area (exposed group), and 200 were from Haojiang, a nearby non-e-waste area (reference group). Levels of blood pressure, plasma vitamin E, serum superoxide dismutase (SOD), serum glutathione peroxidase (GPx), and eight urinary hydroxylated PAHs (OH-PAHs) were measured. Compared with Haojiang children, Guiyu children had higher urinary OH-PAH concentrations but lower systolic pressure, pulse pressure, serum SOD concentration, and serum GPx concentration (all P < 0.05). PAH exposure was associated with lower systolic pressure, pulse pressure, SOD (adjusted β = -0.091, -0.104 and -0.154, respectively, all P < 0.05, in all children), GPx (adjusted β_{∑7LMW-OH-PAHs-T3} = -0.332, only in Haojiang children) and vitamin E (adjusted OR_{∑7LMW-OH-PAHs} = 0.838, 95% CI: 0.706, 0.995, only in Guiyu children). Serum SOD and GPx were associated with higher blood pressure (β_SOD-T2 for diastolic pressure = 0.215 in all children, β_SOD-T3 for systolic pressure = 0.193 in all children, β_SOD-T3 for pulse pressure = 0.281 in high-∑₈OH-PAHs children, β_GPx-T2 = 0.283 and β_GPx-T3 = 0.289 for diastolic pressure in Haojiang children, all P < 0.05). Interactions between PAHs and vitamin E were associated with lower systolic pressure and pulse pressure; simple effects of vitamin E to raise systolic pressure and pulse pressure were only significant in low-∑₈OH-PAHs children. Our results indicate that PAH exposure, especially at high levels, and further antioxidant-decrease are potential risk factors for blood-pressure decrease in children; vascular function of PAH-exposed children may be impaired, manifesting as disordered blood pressure.

Genetic background of high blood pressure is associated with reduced mortality in premature neonates

OBJECTIVE

The aim of our study was to determine if a genetic background of high blood pressure is a survival factor in preterm infants.

DESIGN

Prospective cohort study.

SETTING

Patients were enrolled in 53 neonatal intensive care units.

PATIENTS

Preterm infants with a birth weight below 1500 g.

EXPOSURES

Genetic score blood pressure estimates were calculated based on adult data. We compared infants with high genetic blood pressure estimates (>75th percentile of the genetic score) to infants with low genetic blood pressure estimates (<25th percentile of the genetic score).

MAIN OUTCOME MEASURES

Lowest blood pressure on the first day of life and mortality.

RESULTS

5580 preterm infants with a mean gestational age of 28.1±2.2 weeks and a mean birth weight of 1022±299 g were genotyped and analysed. Infants with low genetic blood pressure estimates had significantly lower blood pressure if compared with infants with high genetic blood pressure estimates (27.3±6.2vs 27.9±6.4, p=0.009, t-test). Other risk factors for low blood pressure included low gestational age (-1.26 mm Hg/week) and mechanical ventilation (-2.24 mm Hg, p<0.001 for both variables, linear regression analysis). Mortality was significantly reduced in infants with high genetic blood pressure estimates (28-day mortality: 21/1395, 1.5% vs 44/1395, 3.2%, p=0.005, Fisher's exact test). This survival advantage was independent of treatment with catecholamines.

CONCLUSIONS

Our study provides first evidence that a genetic background of high blood pressure may be beneficial with regard to survival of preterm infants.

TLR7 agonist modulation of postasphyxial neurophysiological and cardiovascular adaptations in preterm fetal sheep

Activation of Toll-like receptors (TLRs) after hypoxic-ischemic brain injury can exacerbate injury but also alleviate cell loss, as recently demonstrated with the TLR7 agonist Gardiquimod (GDQ). However, TLR agonists also modulate vascular function and neuronal excitability. Thus, we examined the effects of TLR7 activation with GDQ on cardiovascular function and seizures after asphyxia in preterm fetal sheep at 0.7 gestation (104 days, term ∼147 days). Fetuses received sham asphyxia or asphyxia induced by umbilical cord occlusion for 25 min or asphyxia followed by a continuous intracerebroventricular infusion of 3.34 mg of GDQ from 1 to 4 h after asphyxia. Fetuses were monitored continuously for 72 h postasphyxia. GDQ treatment was associated with sustained, moderate hypertension for 72 h (P < 0.05), with a transient increase in heart rate. Electroencephalographic (EEG) power was suppressed for the entire postasphyxial period in both groups, whereas EEG spectral edge transiently increased during the GDQ infusion compared with asphyxia alone (P < 0.05), with higher β- and lower δ-EEG frequencies (P < 0.05). This increase in EEG frequency was not related to epileptiform activity. After the GDQ infusion, there was earlier onset of high-amplitude stereotypic evolving seizures, with increased numbers of seizures and seizure burden (P < 0.05). Hemodynamic function and seizure activity are important indices of preterm wellbeing. These data highlight the importance of physiological monitoring during preclinical testing of potential neuroprotective strategies.

Risk Factors for Necrotizing Enterocolitis in Infants With Patent Arterial Duct. A Retrospective Matched Paired Analysis

Background: The development of necrotizing enterocolitis (NEC) in neonates with patent ductus arteriosus (PDA) is not well-understood. Our aim was to find risk factors for NEC in children with a significant PDA and to assess differences in mortality and duration of hospital stay between patients with PDA and those with PDA and NEC. Methods: We performed a retrospective single center case control study including infants with PDA scheduled for treatment. We compared multiple patient data between patients with PDA and those with PDA and NEC from 2004 to 2018 using 1:2 and 1:1 matching. Results: We used 1:2 matching with 26 NEC patients (cases) and 52 PDA patients without NEC (controls) and 1:1 matching with 5 NEC patients and 5 PDA patients without NEC. NEC patients had lower Apgar score (1'), more congenital malformations, more suspected sepsis, less hypotension, higher minimum platelet count and higher CRP-values during the week before NEC (P < 0.05, respectively). The mortality was higher in NEC cases [29% (9/31)] compared to the control patients [2% (1/57), P < 0.001]. Lower Apgar score (1') was correlated with an increased risk of NEC stage III. Hypotension was inversely correlated with the odds of NEC (OR 0.3). Conclusions: NEC increased mortality in infants with PDA. Hypotension did not increase the risk of NEC in infants with PDA. Routine clinical parameters were not able to predict NEC in infants who suffer from PDA.

Development and validation of a novel scoring system to predict severe intraventricular hemorrhage in very low birth weight infants

OBJECTIVE

We sought to develop and validate a novel scoring system for the prediction of severe intraventricular hemorrhage (SIVH) in very low birth weight infants (VLBWI).

METHODS

This retrospective cohort multicenter study included 615 VLBWI born between 24 and 32 weeks gestational age (GA). Multivariable logistic regression analyses were used to determine which factors evaluated within the first 5 days of life were associated with SIVH and the weights of these variables. The accuracy of the predictive scoring system was prospectively tested in the same units.

RESULTS

The final SIVH scoring system included the following variables: antenatal steroid therapy, GA, birth weight (BW), 1-min Apgar score, mechanical ventilation and hypotension. The SIVH scores used to divide the subjects into three tiers (low-risk (<5), moderate-risk (5-8) and high-risk (>8)) were developed based on these variables. Of infants with a score below 5, 1.2% (4/339) developed SIVH. Of those with a score above 8, 42.5% (17/40) developed SIVH. The scores were successfully verified in 99 VLBWI.

CONCLUSIONS

These findings suggest that among infants with a score >8, the incidence of SIVH is significantly higher. This scoring system can be used to predict the incidence of SIVH during the first 5 days after birth and may contribute to the early intervention in and prevention of SIVH.

European Consensus Guidelines on the Management of Respiratory Distress Syndrome - 2019 Update

As management of respiratory distress syndrome (RDS) advances, clinicians must continually revise their current practice. We report the fourth update of "European Guidelines for the Management of RDS" by a European panel of experienced neonatologists and an expert perinatal obstetrician based on available literature up to the end of 2018. Optimising outcome for babies with RDS includes prediction of risk of preterm delivery, need for appropriate maternal transfer to a perinatal centre and timely use of antenatal steroids. Delivery room management has become more evidence-based, and protocols for lung protection including initiation of CPAP and titration of oxygen should be implemented immediately after birth. Surfactant replacement therapy is a crucial part of management of RDS, and newer protocols for its use recommend early administration and avoidance of mechanical ventilation. Methods of maintaining babies on non-invasive respiratory support have been further developed and may cause less distress and reduce chronic lung disease. As technology for delivering mechanical ventilation improves, the risk of causing lung injury should decrease, although minimising time spent on mechanical ventilation using caffeine and, if necessary, postnatal steroids are also important considerations. Protocols for optimising general care of infants with RDS are also essential with good temperature control, careful fluid and nutritional management, maintenance of perfusion and judicious use of antibiotics all being important determinants of best outcome.

The fetus at the tipping point: modifying the outcome of fetal asphyxia

Brain injury around birth is associated with nearly half of all cases of cerebral palsy. Although brain injury is multifactorial, particularly after preterm birth, acute hypoxia-ischaemia is a major contributor to injury. It is now well established that the severity of injury after hypoxia-ischaemia is determined by a dynamic balance between injurious and protective processes. In addition, mothers who are at risk of premature delivery have high rates of diabetes and antepartum infection/inflammation and are almost universally given treatments such as antenatal glucocorticoids and magnesium sulphate to reduce the risk of death and complications after preterm birth. We review evidence that these common factors affect responses to fetal asphyxia, often in unexpected ways. For example, glucocorticoid exposure dramatically increases delayed cell loss after acute hypoxia-ischaemia, largely through secondary hyperglycaemia. This critical new information is important to understand the effects of clinical treatments of women whose fetuses are at risk of perinatal asphyxia.

Treating Hypotension in Preterm Neonates With Vasoactive Medications

Preterm neonates often have hypotension which may be due to various etiologies. While it is controversial to define hypotension in preterm neonates, various vasoactive medications are commonly used to provide the cardiovascular support to improve the blood pressure, cardiac output, or to treat shock. However, the literature on the systemic and regional hemodynamic effects of these antihypotensive medications in neonates is deficient and incomplete, and cautious translation of findings from other clinical populations and animal studies is required. Based on a literature search on published reports, meta-analytic reviews, and selected abstracts, this review discusses the current available information on pharmacologic actions, clinical effects, and side effects of commonly used antihypotensive medications including dopamine, dobutamine, epinephrine, norepinephrine, vasopressin, and milrinone in preterm neonates.

Cardiovascular Supportive Therapies for Neonates With Asphyxia - A Literature Review of Pre-clinical and Clinical Studies

Asphyxiated neonates often have hypotension, shock, and poor tissue perfusion. Various "inotropic" medications are used to provide cardiovascular support to improve the blood pressure and to treat shock. However, there is incomplete literature on the examination of hemodynamic effects of these medications in asphyxiated neonates, especially in the realm of clinical studies (mostly in late preterm or term populations). Although the extrapolation of findings from animal studies and other clinical populations such as children and adults require caution, it seems appropriate that findings from carefully conducted pre-clinical studies are important in answering some of the fundamental knowledge gaps. Based on a literature search, this review discusses the current available information, from both clinical studies and animal models of neonatal asphyxia, on common medications used to provide hemodynamic support including dopamine, dobutamine, epinephrine, milrinone, norepinephrine, vasopressin, levosimendan, and hydrocortisone.