Early determinants of right and left ventricular output in ventilated preterm infants

Targeted Cerebral Oxygenation Using Dedicated Treatment Versus Usual Care in Extremely Preterm Infants: Protocol for a Multicentre International Phase II Randomised Controlled Trial

BACKGROUND

Near infrared spectroscopy (NIRS) allows continuous monitoring of cerebral oxygenation and therefore has the potential to be neuroprotective. Recurrent episodes of cerebral hypo-and/or hyperoxia may result in brain injury. The Safe-BoosC-II study reported stable cerebral oxygenation in extremely preterm infants by combining a dedicated treatment guideline with NIRS monitoring using several devices and adult sensors. The ability to maintain stable cerebral oxygenation with a dedicated treatment algorithm using one type of NIRS device with neonatal sensors has not been previously investigated.

METHODS

In this multicentre, 2-arm, parallel, single-blinded, phase II RCT, stratified by gestation and hospital site, 100 participants born < 29 weeks' gestation (inborn and outborns, singleton and twins) will be randomised to targeted cerebral oxygenation using dedicated treatment or usual care with blinded cerebral NIRS monitoring for the first 5 days of life. We will exclude infants > 6 h of age, those with congenital anomaly requiring major surgery or a genetic disorder, and triples or higher multiple births. The primary outcome is the burden of cerebral hypoxia and hyperoxia for the first 5 days after birth expressed as percent hours.

DISCUSSION

The findings of this trial will provide essential information on (i) validating results from the Safe-BoosC-II study, considering the differences in the study methodology between the two trials (ii) strengthening support for routine use of cerebral NIRS monitoring in this population and (iii) informing the design of future RCTs on the effects of targeted cerebral oxygenation on neurodevelopment in early childhood as the primary outcome.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry registration number ACTRN12621000778886.

Cardiac biomarkers predict low right ventricle performance in neonatal encephalopathy

OBJECTIVE

Study the association between cardiac biomarkers and echocardiography parameters of ventricular performance in neonates with neonatal encephalopathy (NE).

METHODS

Prospective observational study (2016-2021) of neonates undergoing therapeutic hypothermia (TH). Neonates with brain injury had repeated echocardiography and biomarkers measurements on day of life (DOL) 2, 3, 4, and 10. Pearson correlation and generalized linear mixed effect models were used to account for repeated measurements. Receiver operating characteristic curves were constructed to assess sensitivity/specificity.

RESULTS

56 neonates had 128 measurements. Creatine Kinase (CK) and cardiac troponin-I (CTn-I) were associated with right ventricular (RV) function. A CK of 1961 U/L and a CTn-I of 91 ng/L identified low Tricuspid Annular Plane Systolic Excursion (<7 mm) with sensitivities of 93% and 79%, and specificities of 55% and 74%, respectively.

CONCLUSIONS

Elevated CK and CTn-I were associated with decreased RV performance. Trending these markers can be used to suspect altered RV function and may flag optimal timing for evaluation(s) by echocardiography during TH.

Cardiopulmonary Physiology of Hypoxemic Respiratory Failure Among Preterm Infants with Septic Shock

OBJECTIVE

To examine cardiopulmonary physiological alterations associated with hypoxemic respiratory failure (HRF; fraction of inspired oxygen ≥0.60) among preterm neonates requiring vasopressors/inotropes during sepsis (septic shock).

STUDY DESIGN

We conducted a retrospective cohort study from 2015 through 2022 at a tertiary neonatal intensive care unit. Neonates <34 weeks gestational age who had septic shock and underwent a comprehensive targeted neonatal echocardiography (TNE) ≤72 hours of sepsis onset were included. TNE findings of patients with shock and HRF were compared with those with shock without HRF. Indices of pulmonary vascular resistance (PVR), right ventricular (RV) and left ventricular (LV) systolic and diastolic function, measured using conventional, tissue Doppler imaging and speckle-tracking echocardiography, were examined.

RESULTS

Of 52 included infants with septic shock, 19 (37%) also had HRF. Baseline characteristics were similar. On TNE, although the HRF group more frequently had bidirectional/right-to-left flow across the patent ductus arteriosus (67% vs 33%; P = .08), all indices of PVR and RV function were similar. However, the HRF group demonstrated reduced LV systolic function (ejection fraction, 51.8% ± 12.3% vs 62.6% ± 13.0%; global peak systolic longitudinal strain -15.2% ± 4.5% vs -18.6% ± 4.5%), diastolic function (early [2.3 ± 1.0/s vs 3.6 ± 1.2/s]) and late (2.4/s [IQR, 1.9-2.6/s] vs 2.8/s [2.3-3.5/s] diastolic strain rate), and higher frequency of LV output <150 mL/min/kg (44% vs 12%) (all P < .05).

CONCLUSIONS

Acute HRF occurring in preterm neonates with septic shock is associated with alterations in TNE measures of LV function, and not PVR or RV function. Future studies should evaluate the impact of supporting LV function in these patients.

A recommendation for the use of electrical biosensing technology in neonatology

Non-invasive cardiac output monitoring, via electrical biosensing technology (EBT), provides continuous, multi-parameter hemodynamic variable monitoring which may allow for timely identification of hemodynamic instability in some neonates, providing an opportunity for early intervention that may improve neonatal outcomes. EBT encompasses thoracic (TEBT) and whole body (WBEBT) methods. Despite the lack of relative accuracy of these technologies, as compared to transthoracic echocardiography, the use of these technologies in neonatology, both in the research and clinical arena, have increased dramatically over the last 30 years. The European Society of Pediatric Research Special Interest Group in Non-Invasive Cardiac Output Monitoring, a group of experienced neonatologists in the field of EBT, deemed it appropriate to provide recommendations for the use of TEBT and WBEBT in the field of neonatology. Although TEBT is not an accurate determinant of cardiac output or stroke volume, it may be useful for monitoring longitudinal changes of hemodynamic parameters. Few recommendations can be made for the use of TEBT in common neonatal clinical conditions. It is recommended not to use WBEBT to monitor cardiac output. The differences in technologies, study methodologies and data reporting should be addressed in ongoing research prior to introducing EBT into routine practice. IMPACT STATEMENT: TEBT is not recommended as an accurate determinant of cardiac output (CO) (or stroke volume (SV)). TEBT may be useful for monitoring longitudinal changes from baseline of hemodynamic parameters on an individual patient basis. TEBT-derived thoracic fluid content (TFC) longitudinal changes from baseline may be useful in monitoring progress in respiratory disorders and circulatory conditions affecting intrathoracic fluid volume. Currently there is insufficient evidence to make any recommendations regarding the use of WBEBT for CO monitoring in neonates. Further research is required in all areas prior to the implementation of these monitors into routine clinical practice.

Early Echocardiographic Predictors of Eventual Need for Patent Ductus Arteriosus Treatment: A Retrospective Study

OBJECTIVE

Hemodynamically significant patent ductus arteriosus (hsPDA) in preterm neonates is associated with end-organ injury including intraventricular hemorrhage. Early treatment may reduce morbidities but may result in overtreatment. This study aimed to examine the association between commonly obtained echocardiographic markers within the first 12 hours of life and eventual treatment of an hsPDA.

STUDY DESIGN

Patients with <32 weeks' gestational age had blinded echocardiograms done within the first 12 hours of life as part of research protocols. Subsequent treatment of the patent ductus arteriosus (PDA) was determined by the clinical team independent of echocardiogram results. t-tests and chi-square tests were done for continuous data and categorical outcomes. A receiver operating curve was created to optimize cutoff values.

RESULTS

 Among 199 neonates studied (mean time of echocardiogram 6.7 h after birth), those needing PDA treatment had higher left ventricular output (LVO), right ventricular output (RVO), and superior vena cava (SVC) flow (p-values 0.007, 0.044, and 0.012, respectively). Cutoffs for predicting PDA treatment were LVO > 204 mL/kg/min (63% sensitivity, 66% specificity), RVO > 221 mL/kg/min or SVC flow > 99 mL/kg/min (sensitivities 70 and 43%, specificities 48 and 73%, respectively).

CONCLUSION

 Preterm neonates with higher markers of cardiac output in the first 12 hours of birth later required PDA treatment. These data are the first to use standard cardiac output measures in the first 12 hours of life to predict the need for future PDA treatment. Further prospective studies will need to be performed to corroborate these associations between echocardiographic markers and clinical outcomes/morbidities.

KEY POINTS

· Early diagnosis of hsPDA may prevent severe morbidity and death.. · There are echocardiographic markers beyond duct size and flow direction that may aid early diagnosis.. · Cardiac output markers within the first 12 hours of life may predict need for treatment of hsPDA..

Association between patent ductus arteriosus flow and home oxygen therapy in extremely preterm infants

BACKGROUND

Central blood flow measurements include the estimation of right and left ventricular output (RVO, LVO), superior vena cava (SVC) flow, and calculated patent ductus arteriosus (PDA) flow. We aimed to provide an overview of the maturation patterns of these values and the relationship between PDA flow and the need for home oxygen therapy.

METHODS

This prospective single-center study was conducted in infants born at <26 weeks of gestation. We performed echocardiographic measurements five times during their life (from the 4th post-natal day to the 36th postmenstrual week).

RESULTS

Sixty patients with a mean birth weight of 680 (590, 760) g were included. Postnatal development of LVO and PDA flow peaked at the end of the second postnatal week (427 and 66 mL/kg/min, respectively). The RVO increased between days 4 and 7-8. The SVCF was most stable. The development curves of PDA flow differed between the groups with (n = 28; 47%) and without home oxygen therapy.

CONCLUSION

We present the central blood flow values and their postnatal development in infants <26 weeks of gestation. This study demonstrates the association between PDA flow and the future need for home oxygen therapy.

IMPACT

This study enriches our knowledge of the long-term development of central blood flow parameters and derived patent ductus arteriosus (PDA) flow in extremely preterm infants (<26 weeks). While pulmonary resistance decreased, PDA flow continued to increase from day 4 to the end of the second week of life. Similarly, left ventricular output increased as a marker of preload. The superior vena cava flow remained stable. The observed association between PDA flow and an unfavorable respiratory outcome is important for future studies focusing on the prevention of chronic lung disease.

Inter-observer variability of right ventricular output measurement in newborn infants: an observational study

Neonatologist Performed Echocardiography (NPE) is one of the emerging technologies used to evaluate Systemic Blood Flow (SBF) in term and preterm infants. Right Ventricular Output (RVO) can assess SBF correctly in the absence of significant interatrial or interventricular shunts, even in the presence of a large patent ductus arteriosus (PDA), but only few studies evaluated inter-observer variability in neonates. Furthermore, measuring pulmonary peak flow (PF) provides a simple screening tool for low SBF state, easier and faster to perform than RVO; no previous studies evaluated PF inter-observer variability. To describe inter-observer variability of RVO and PF measurement in neonates. We conducted a prospective observational study in term and preterm infants admitted to the Neonatal Intensive Care Unit (NICU). Echocardiographic examinations were performed by two expert neonatologists, blinded to each other. Recordings were analyzed off-line to assess RVO and PF variability between observers. We analyzed a cohort of 33 neonates, 17 of them born prematurely. Inter-observer mean difference for RVO was 22,1 mL/kg/min (p = 0.005); the biggest discrepancy was due to pulmonary valve diameter measurement (p = 0.0001). Inter-observer mean difference for PF measurement was not statistically significant. We found a statistically significant inter-observer variability for RVO measurement, consistent with previous reports; PF instead showed low inter-observer variability. For this reason, PF could be evaluated in future studies as a surrogate for RVO in both term and preterm infants, especially in emergency conditions or in presence of a poor echocardiographic window.

Hemodynamic evaluation in preterm infants using ultrasonic cardiac output monitor (USCOM)

We aimed to establish reference ranges for USCOM parameters in preterm infants, determine factors that affect cardiac output, and evaluate the measurement repeatability. This retro-prospective study was performed at Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy. We included infants below 32 weeks of gestational age (GA) and/or 1500 g of birth weight (BW). We excluded infants with congenital heart diseases or hemodynamic instability. Measurements were performed at 3 ± 1, 7 ± 2, and 14 ± 2 postnatal days. We analyzed 204 measurements from 92 patients (median GA = 30.57 weeks, BW = 1360 g). The mean (SD) cardiac output (CO) was 278 (55) ml/min/kg, cardiac index (CI) was 3.1 (0.5) L/min/m2, and systemic vascular resistance (SVRI) was 1292 (294) d*s*cm-5/m2. CO presented a negative correlation with postmenstrual age (PMA), while SVRI presented a positive correlation with PMA. The repeatability coefficient was 31 ml/kg/min (12%).  Conclusion: This is the first study describing reference values for USCOM parameters in hemodynamically stable preterm infants and factors affecting their variability. Further studies to investigate the usefulness of USCOM for the longitudinal assessment of patients at risk for cardiovascular instability or monitoring the response to therapies are warranted. What is Known: • The ultrasonic cardiac output monitoring (USCOM) has been widely used on adult and pediatric patients and reference ranges for cardiac output (CO) by USCOM have been established in term infants. What is New: • We established reference values for USCOM parameters in very preterm and very-low-birth-weight infants; the reference ranges for CO by USCOM in the study population were 198-405 ml/kg/min. • CO normalized by body weight presented a significant negative correlation with postmenstrual age (PMA); systemic vascular resistance index presented a significant positive correlation with PMA.

Effect of sleeping position on cardiac output, pulmonary pressure, and superior vena cava flow in healthy term infants

BACKGROUND

Although the mechanism of action in newborns is unknown, sleep positioning is associated with many pathophysiological events. This study aimed to compare the effects of supine and prone sleeping positions on cardiac output (CO), systolic pulmonary arterial pressure (SPAP), and superior vena cava (SVC) flow in healthy newborns.

METHODS

In the first 24-72 h of life, 40 healthy term newborns born in the same hospital were included in this prospective, cross-sectional, observational study. CO, SVC flow, and SPAP values of newborns in the supine and prone sleeping positions were calculated using echocardiographic examination. The measurements were statistically compared.

RESULTS

In the supine sleeping position, CO, SVC flow, and SPAP were 235.00 (193.07-283.30) ml/kg/min, 92.80 (77.82-121.87) ml/kg/min, and 27.85 (24.70-30.48) mmHg. In the prone sleeping position, CO, SVC flow, and SPAP were measured as 195.35 (166.00-229.40) ml/kg/min, 67.25 (51.82-96.66) ml/kg/min, 31.60 (28.45-37.20) mmHg, respectively. Depending on sleeping position, these variables were significantly different between the groups.

CONCLUSION

SVC flow and CO decreased in the prone sleeping position compared to the supine sleeping position in healthy newborns, whereas SPAP increased. The different hemodynamic effects of sleeping position on the cardiac, pulmonary, and nervous systems should be considered as flow and pressure changes are important in newborns.

Cardiac biomarkers and left ventricular systolic function in former very preterm infants and term controls at preschool age

Introduction

Due to improvements in perinatal care, survival rates of preterm infants have improved during the last decades. However, these infants remain at risk of developing cardiovascular sequelae later in life. This study aimed to investigate the cardiac biomarkers and left ventricular systolic function in former preterm infants in comparison with term controls at preschool age.

Methods

The study included children aged 5-7 years old born below 32 weeks of gestational age. The control group consisted of same-age children born at term. Basic data of study participants were collected using questionnaires and follow-up databases. During the study visit, we recorded anthropometric data and blood pressure readings, determined high-sensitive cardiac troponin T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) concentrations, and calculated fractional shortening (FS) and left ventricular mass (LVM).

Results

Term-born (n = 25; median gestational age, 40.1 weeks) compared with preterm-born infants (n = 80; median gestational age 29.6 weeks) showed no significant differences in the median concentration of hs-cTnT [median, 3.5 (IQR 3.5; 3.5) vs. 3.5 (3.5; 3.5) ng/L, p = 0.328] and the median concentration of NT-pro-BNP [median, 91.0 (IQR 40.8; 150.3) vs. 87.5 (50.1; 189.5) ng/L, p = 0.087]. FS and LVM/LVMI were not significantly different between the two groups.

Conclusion

At preschool age, we observed no significant differences in cardiac biomarkers and left ventricular systolic function in preterm infants. Further studies are warranted to explore the potential of cardiac biomarkers as a prognostic tool for subclinical cardiac alterations after preterm birth.

The role of point-of-care ultrasound in the management of neonates with congenital diaphragmatic hernia

In the last few years, current evidence has supported the use of point-of-care ultrasound (POCUS) for a number of diagnostic and procedural applications. Considering the valuable information that POCUS can give, we propose a standardized protocol for the management of neonates with a congenital diaphragmatic hernia (CDH-POCUS protocol) in the neonatal intensive care unit. Indeed, POCUS could be a valid tool for the neonatologist through the evaluation of 1) cardiac function and pulmonary hypertension; 2) lung volumes, postoperative pleural effusion or pneumothorax; 3) splanchnic and renal perfusion, malrotations, and/or signs of necrotizing enterocolitis; 4) cerebral perfusion and eventual brain lesions that could contribute to neurodevelopmental impairment. In this article, we discuss the state-of-the-art in neonatal POCUS for which concerns congenital diaphragmatic hernia (CDH), and we provide suggestions to improve its use. IMPACT: This review shows how point-of-care ultrasound (POCUS) could be a valid tool for managing neonates with congenital diaphragmatic hernia (CDH) after birth. Our manuscript underscores the importance of standardized protocols in neonates with CDH. Beyond the well-known role of echocardiography, ultrasound of lungs, splanchnic organs, and brain can be useful. The use of POCUS should be encouraged to improve ventilation strategies, systemic perfusion, and enteral feeding, and to intercept any early signs related to future neurodevelopmental impairment.

T-Piece resuscitator versus self-inflating bag for delivery room resuscitation in preterm neonates: a randomized controlled trial

The establishment of adequate ventilation is the cornerstone of neonatal resuscitation in the delivery room (DR). This parallel-group, accessor-blinded randomized controlled trial compared the changes in peripheral oxygen saturation (SpO2), heart rate (HR), and cerebral regional oxygen saturation (crSO2) with the use of a T-piece resuscitator (TPR) versus self-inflating bag (SIB) as a mode of providing positive pressure ventilation (PPV) during DR resuscitation in preterm neonates. Seventy-two preterm neonates were randomly allocated to receive PPV with TPR (n = 36) or SIB (n = 36). The primary outcome was SpO2 (%) at 5 min. The secondary outcomes included the time to achieve a SpO2 ≥ 80% and > 85%, HR > 100/min, fractional-inspired oxygen (FiO2) requirement, minute-specific SpO2, HR and FiO2 trends for the first 5 min of life, need for DR-intubation, crSO2, need and duration of respiratory support, and other in-hospital morbidities. Mean SpO2 at 5 min was 74.5 ± 17.8% and 69.4 ± 22.4%, in TPR and SIB groups, respectively [Mean difference, 95% Confidence Interval 5.08 (-4.41, 14.58); p = 0.289]. No difference was observed in the time to achieve a SpO2 ≥ 80% and > 85%, HR > 100/min, the requirement of FiO2, DR-intubation, and the need and duration of respiratory support. There was no significant difference in the minute-specific SpO2, HR, and FiO2 requirements for the first 5 min. CrSO2 (%) at one hour was lower by 5% in the TPR group compared to SIB; p = 0.03. Other complications were comparable.

CONCLUSIONS

TPR and SIB resulted in comparable SpO2 at 5 min along with similar minute-specific SpO2, HR, and FiO2 trends.

CLINICAL TRIAL REGISTRATION

Clinical trial registry of India, Registration no: CTRI/2021/10/037384, Registered prospectively on: 20/10/2021, https://ctri.icmr.org.in/ .

WHAT IS KNOWN

• Compared to self-inflating bags (SIB), T-piece resuscitators (TPR) provide more consistent inflation pressure and tidal volume as shown in animal and bench studies. • There is no strong recommendation for one device over the other in view of low certainty evidence.

WHAT IS NEW

• TPR and SIB resulted in comparable peripheral oxygen saturation (SpO2) at 5 min along with similar minute-specific SpO2, heart rate, and fractional-inspired oxygen requirement trends. • Short-term complications and mortality rates were comparable with both devices.

Normal values for superior vena cava flow in preterm neonates using a new echocardiographic approach

OBJECTIVE

Recently, a novel approach to imaging Superior Vena Cava (SVC) flow has been presented, showing better repeatability and better agreement with MRI-derived SVC flow measures. The objective was to establish normal values of SVC flow with the novel approach in the first 48 h of life.

STUDY DESIGN

This was a prospective, observational study. All infants with gestational age (GA) less than 31 weeks were eligible. Echocardiographic evaluation was performed at 5, 12, 24, 48 h of postnatal life. A subgroup of uncomplicated infants was studied to define a normal range for SVC flow.

RESULTS

Forty-five infants were enrolled. We estimated normative values in a subgroup of 31 uncomplicated infants. The median SVC flow significantly increases from 83 ml/kg/min at 5 h of life to 153 ml/kg/min at 48 h (p < .001).

CONCLUSION

Using the novel approach we derived normal values of SVC flow in a cohort of uncomplicated preterm population at high risk for developing IVH.

Clinical and haemodynamic characteristics of preterm infants with early onset sepsis

AIM

Early onset sepsis (EOS) in preterm infants is associated with high morbidity and mortality. Improved characterisation of the haemodynamic presentation of EOS could lead to more effective and targeted treatments.

METHODS

We performed a retrospective observational study of preterm infants ≤32 week' gestation with EOS between 2010 and 2020 and gathered clinical, haemodynamic and echocardiographic data.

RESULTS

Of the 2198 admitted infants, 27 infants (median gestational age 28 weeks, median birthweight 1174 g) developed EOS with predominantly gram-negative pathogens and the overall mortality rate was 33.3%. Besides hypotension, clinical signs were non-specific, and over half of infants were normotensive in the first 72 h of life. Those with hypotension received more fluid resuscitation, inotropic support and had a higher mortality compared to the normotensive infants. Cardiac ultrasound was available in 18 infants and commonly revealed higher as expected cardiac output, pulmonary hypertension and diastolic dysfunction.

CONCLUSION

Preterm infants with EOS had a high mortality rate, especially when they progressed from sepsis to septic shock. Echocardiography revealed a normal haemodynamic pattern, or one suggestive of vasodilatation and warm shock physiology. Targeting this pathophysiology earlier might improve outcomes.

Multimodal Assessment of Systemic Blood Flow in Infants

The assessment of systemic blood flow is a complex and comprehensive process with clinical, laboratory, and technological components. Despite recent advancements in technology, there is no perfect bedside tool to quantify systemic blood flow in infants that can be used for clinical decision making. Each option has its own merits and limitations, and evidence on the reliability of these physiology-based assessment processes is evolving. This article provides an extensive review of the interpretation and limitations of methods to assess systemic blood flow in infants, highlighting the importance of a comprehensive and multimodal approach in this population.

Impact of Aortic Diameter Measurements at Three Anatomical Landmarks on Left Ventricular Output Calculation in Neonates

OBJECTIVES

To assess reproducibility and accuracy of left ventricular output (LVO) quantifications in neonates, when left ventricular outflow tract diameter (LVOTD) was measured at the hinges of the aortic valve (AV), at the aortic sinus (AS), and at the sinotubular junction (STJ).

METHODS

This was an observational study. In the first cohort of very preterm neonates, we assessed intraobserver and interobserver repeatability of LVOTD measured at the AV, AS, and STJ and of the corresponding LVO. In the second cohort of older neonates, we compared paired LVO measurements by echo and magnetic resonance imaging (MRI).

RESULTS

In the first cohort of 48 neonates, mean (standard deviation) weight and age at scan were 1046 (302) g and 28.1 (2.7) weeks. Interobserver bias (95% limits of agreement [LOA]) for LVOTD at the AV, AS, and STJ was 0 (-0.3 to 0.3) mm, 0 (-0.7 to 0.7) mm, and 0 (-0.8 to 0.7) mm, respectively. Interobserver bias (95% LOA) for the corresponding LVO was -1.3 (-31 to 33) ml/kg/min, -0.5 (-88 to 87) ml/kg/min, and -7.2 (-83 to 69) ml/kg/min, respectively. In the second cohort of 10 neonates, median (range) weight and age at scan were 1942 (970-3640) g and 37.2 (31.7-39.8) weeks. LVO measured at the AV showed stronger agreement with MRI: bias (LOA) -10.6 (-74 to 52) ml/kg/min, compared to LVO measured at AS and STJ: 194 (-0.5 to 388) ml/kg/min and 43 (-72 to 159) ml/kg/min respectively.

CONCLUSIONS

Reproducibility and accuracy of LVO quantification by echo were better when aortic diameter was measured at AV.

Mitral valve Doppler for cardiac output assessment in preterm neonates

INTRODUCTION

Cardiac output (CO) assessment in neonates is commonly done by echocardiography. It is unclear which is the best site to measure the left ventricular (LV) outflow tract for CO assessment (the aortic valve [AV] aortic sinus [AS] or the sinotubular junction [STJ]). In the normal heart, the blood flow entering the LV equals the blood ejected from it. Therefore, measuring the blood flow into the LV through the mitral valve (MV) is an alternative way to measure CO.

METHODS

In stable preterm infants the MV CO was compared with the right ventricular (RV) CO and the three ways to measure LV CO, in 30 stable preterm neonates. Interobserver variability for MV CO was established.

RESULTS

In the 30 neonates studied, MV CO was best correlated and had a minimal bias to the RV CO and LV CO measured at the STJ. Left ventricular CO measured at the AV and AS had significant bias relative to RV CO and MV CO. MV CO inter-observer variability was similar to other echocardiographic CO assessment methods.

CONCLUSION

MV CO may be used as an alternative way to assess CO. The STJ may be the optimal site to measure LV outflow tract.

Impact of intrauterine growth restriction on cerebral and renal oxygenation and perfusion during the first 3 days after birth

Intrauterine growth restriction (IUGR) is associated with a higher incidence of perinatal complications as well as cardiovascular and renal diseases later on. A better insight into the disease mechanisms underlying these sequalae is important in order to identify which IUGR infants are at a higher risk and find strategies to improve their outcome. In this prospective case-control study we examined whether IUGR had any effect on renal and cerebral perfusion and oxygen saturation in term neonates. We integrated near-infrared spectroscopy (NIRS), echocardiographic, Doppler and renal function data of 105 IUGR infants and 105 age/gender-matched controls. Cerebral and renal regional oxygen saturation values were measured by NIRS during the first 12 h after birth. Echocardiography alongside Doppler assessment of renal and anterior cerebral arteries were performed at 6, 24, 48 and 72 h of age. Glomerular and tubular functions were also assessed. We found a left ventricular dysfunction together with a higher cerebral oxygen saturation and perfusion values in the IUGR group. IUGR term infants showed a higher renal oxygen saturation and a reduced oxygen extraction together with a subclinical renal damage, as indicated by higher values of urinary neutrophil gelatinase-associated lipocalin and microalbumin. These data suggest that some of the haemodynamic changes present in growth-restricted foetuses may persist postnatally. The increased cerebral oxygenation may suggest an impaired transition to normal autoregulation as a consequence of intra-uterine chronic hypoxia. The higher renal oxygenation may reflect a reduced renal oxygen consumption due to a subclinical kidney damage.

Intraventricular hemorrhage prediction in premature neonates in the era of hemodynamics monitoring: a prospective cohort study

Unstable hemodynamics and prematurity are the main players in intraventricular hemorrhage (IVH) development. Our objective was to study 8 the use of superior vena cava flow (SVCF), left ventricular output (LVO), and right ventricular output (RVO), and anterior cerebral artery (ACA) Doppler measures in prediction of IVH in the first week of life in preterm infant ≤ 32 weeks and birth weight ≤ 1500 g. This prospective cohort study was conducted in 55NICU of Alexandria University maternity hospital. Of 147 enrolled patients, 132 infants born ≤ 32 weeks GA and birth weight ≤ 1500 g were eligible for- the study. One hundred twenty-seven infants completed the study. Infants were scanned for ACA-RI using transfontanellar ultrasound, and SVCF, LVO, and RVO using functional echocardiography in the first 24 h after birth. Patients had another two scans on DOL3 and 7 to detect IVH development. Low SVCF and high ACA-RI significantly increased the risk of IVH using logistic regression models with OR, 3.16; 95%CI, 1.19-8.39; P = 0.02 and OR, 1.64; 95%Cl, 1.10-2.44; P = 0.02, respectively. Low SVCF and high ACA-RI significantly increased risk of catastrophic IVH P = 0.025 and 0.023, respectively. Combined use of low SVCF < 55 ml/kg/min and ACA-RI > 0.75 is predictor of IVH with sensitivity 40.8% and 82.1% specificity.

CONCLUSIONS

There are strong relations between both low SVCF and high ACA-RI, and IVH development in premature neonates ≤ 32 weeks and birth weight ≤ 1500 g, with more significance towards catastrophic IVH. Admission RSS and LVO are the strongest factors affecting SVCF. Maternal anemia, patent ductus arteriosus size (mm/kg), and capillary refill time were significantly associated with high ACA-RI. These findings help in more understanding of pathophysiological factors affecting central perfusion that might affect the longer term neurodeveopmental outcome.

TRIAL REGISTRATION

This work was registered in clinical trial.gv no NCT05050032.

WHAT IS KNOWN

•Whether SVCF and RI-ACA can predict IVH in preterm neonates is still debatable.

WHAT IS NEW

•Low SVC flow and high ACA-RI significantly increased risk of IVH, confirming the role of hypoperfusion-reperfusion cycle in IVH development. The most striking result that combined metrics using the cut-off value of < 41 ml/kg/min for SVCF and > 0.85 for ACA-RI "in the first day of life" can correctly reject the presence of IVH in 98% of patients "during the first week of life."

The effect of placental transfusion on hemodynamics in premature newborns: a randomized controlled trial

Despite of growing evidence of the beneficial effects of placental transfusion techniques, there is no available sufficient data about their effects on vulnerable hemodynamics and myocardium of premature infants. The purpose of this work is to study ventricular functions and hemodynamics after applying different placental transfusion techniques, delayed cord clamping (DCC), cut cord milking (C-UCM), and intact cord milking (I-UCM). Sixty-four infants delivered whether by C-section or vaginal delivery were randomly assigned to undergo C-UCM (20-30 cm), I-UCM (3-4 strippings), and DCC (30-60 s). Functional echocardiography was done on day 1 and day 3 of life for 57 infants. Primary outcome variable was superior vena cava flow measurement in infants having placental transfusion in the first 24 h of life and between 64 and 72 h. Secondary outcomes were other echocardiographic and clinical hemodynamic parameters, and biventricular functions in those infants. Of a total 196 preterm infants ≤ 32 weeks delivered in the study period, from January 2021 to August 2021, 57 infants were eligible and survived till the second examination. They were randomly assigned to the three groups. Neonates randomly assigned to DCC had significantly higher superior vena cava flow and lower right ventricular systolic function in the first 24 h of life. This finding vanished at day 3. Neonates undergone different methods of placental transfusions had similar hemoglobin, admission temperature, and mean blood pressure in the first 24 h of life.

CONCLUSION

Despite their potential benefits, placental transfusions have shown to alter the hemodynamics and adversely affect myocardial function of premature neonates.

TRIAL REGISTRATION

This trial was registered in the clinical trial gov NCT04811872.

WHAT IS KNOWN

• Placental transfusion techniques might have benefits regarding prematurity- related morbidities and mortality.

WHAT IS NEW

• Placental transfusion might adversely affect the myocardium and alter hemodynamics in premature infants.

Left Ventricular Dysfunction Persists in the First Week after Re-Warming following Therapeutic Hypothermia for Hypoxic-Ischaemic Encephalopathy

OBJECTIVES

The aim of this study was to assess serial myocardial function in newborn infants receiving therapeutic hypothermia (TH) as treatment for moderate to severe hypoxic-ischaemic encephalopathy (HIE).

METHODS

Serial echocardiography was performed in 20 term infants receiving TH on days 1-3 and again after re-warming. Left ventricular (LV) fractional shortening, LV cardiac output, and tissue Doppler imaging-derived myocardial velocities and myocardial performance index were measured. Similar assessments were obtained from 20 well term infants within 48 h of birth.

RESULTS

LV fractional shortening (LVFS) was similar between cases and controls during all measurements (25.3% vs. 27.4%). The mean LV cardiac output on day 1 was significantly lower in cases (109 mL/kg/min) than in controls (162 mL/kg/min) but increased after re-warming (145 mL/kg/min). All myocardial velocities were significantly lower in cases on day 1, increased during TH, but LV indices remained consistently lower compared to controls even after re-warming. LV myocardial performance index was higher in cases compared to controls on day 1, improved during TH but remained abnormal after re-warming. The right ventricular myocardial performance index was similar between cases and controls.

CONCLUSION

Among infants affected by moderate to severe HIE, LV function appears to be more affected than right ventricular function with LV dysfunction persisting after completion of TH. LVFS was not useful to determine dysfunction in this cohort.

Neonatal Impedance Cardiography in Asphyxiated Piglets-A Feasibility Study

OBJECTIVES

Impedance cardiography (ICG) is a non-invasive method for continuous cardiac output measurement and has the potential to improve monitoring and treatment of sick neonates. PhysioFlow^® is a signal-morphology ICG-system showing promising results in adults with low and high cardiac output, but no data from neonates or neonatal models exist. The aim of this study was to investigate PhysioFlow^® feasibility in asphyxiated newborn piglets.

METHODS

Fifteen piglets, under continuous arterial heart rate (HR) and blood pressure (BP) monitoring, were asphyxiated until asystole. Cardiopulmonary resuscitation was performed and the piglets monitored after return of spontaneous circulation (ROSC). Arterial lactate was measured at baseline, every 5 min throughout asphyxiation, at asystole, and at 10 min and later every 30 min after ROSC. PhysioFlow^® measured cardiac stroke volume (SV) and HR, and calculated cardiac index (CI) (L/m²/min). Registrations with a signal quality < 75% were excluded, and registrations recorded for 30 min from start of asphyxia analyzed. Pearson correlations were calculated for CI; and HR, mean BP and blood lactate.

RESULTS

The piglets were asphyxiated for median (interquartile range) 30 (20-35) min and had a lactate at asystole of 15.0 (9.1-17.0) mmol/L. Out of a total of 20.991 registrations in all animals combined, there were 10.148 (48.3%) registrations with a signal quality ≥ 75%. Signal quality ≥ 75% varied in individual piglets from 7 to 82% of registrations. We analyzed 1.254 registrations recorded 30 min from initiation of asphyxia, i.e., in piglets with brief asphyxia times, this included cardiopulmonary resuscitation and post-ROSC observation. There was a positive correlation between CI and SVI (r = 0.90, p < 0.001), and between CI and HR (r = 0.446, p < 0.001). There was no correlation between CI, or mean BP or lactate (p = 0.98 and 0.51, respectively).

CONCLUSION

About half of ICG-registrations in asphyxiated piglets were of good quality. However, signal quality was highly variable between piglets. In total, there was a higher proportion of reliable ICG-registrations than reported from clinical delivery room studies using electrical velocimetry. Our data are physiologically plausible and supports further research evaluating PhysioFlow^® for cardiac output monitoring in perinatal asphyxia. In particular, factors influencing inter-individual variations in signal quality should be explored.

Blood pressure changes during the first 24 hours of life and the association with the persistence of a patent ductus arteriosus and occurrence of intraventricular haemorrhage

Very low birthweight (VLBW) infants are at risk of intraventricular haemorrhage (IVH) and delayed closure of ductus arteriosus. We investigated mean arterially recorded blood pressure (MAP) changes during the first day of life in VLBW infants as potential risk factors for a patent ductus arteriosus (PDA) and IVH. This retrospective cohort study exploring MAP changes during adaption and risk factors for a PDA and IVH comprised 844 VLBW infants admitted to the Helsinki University Children’s Hospital during 2005–2013. For each infant, we investigated 600 time-points of MAP recorded 4–24 hours after birth. Based on blood pressure patterns revealed by a data-driven method, we divided the infants into two groups. Group 1 (n = 327, mean birthweight = 1019 g, mean gestational age = 28 + ^1/7 weeks) consisted of infants whose mean MAP was lower at 18–24 hours than at 4–10 hours after birth. Group 2 (n = 517, mean birthweight = 1070 g, mean gestational age = 28 + ^5/7 weeks) included infants with a higher mean MAP at 18–24 hours than at 4–10 hours after birth. We used the group assignments, MAP, gestational age at birth, relative size for gestational age, surfactant administration, inotrope usage, invasive ventilation, presence of respiratory distress syndrome or sepsis, fluid intake, and administration of antenatal steroids to predict the occurrence of IVH and use of pharmacological or surgical therapy for a PDA before 42 weeks of gestational age. Infants whose mean MAP is lower at 18–24 hours than at 4–10 hours after birth are more likely to undergo surgical ligation of a PDA (odds ratio = 2.1; CI 1.14–3.89; p = 0.018) and to suffer from IVH (odds ratio = 1.83; CI 1.23–2.72; p = 0.003).

Regional Oxygenation and Perfusion Monitoring to Optimize Neonatal Packed Red Blood Cell Transfusion Practices: A Systematic Review

Contemporary packed red blood cell transfusion practices in anaemic preterm infants are primarily based on measurement of hemoglobin or haematocrit. In neonatal intensive care units, most preterm infants receive at least 1 packed red cell transfusion as standard treatment for anaemia of prematurity. Clinicians are faced with a common question "at what threshold should anaemic preterm infants receive packed red blood cell transfusion?". While evidence from interventional trials offers a range of haemoglobin levels to clinicians on thresholds to initiate red cell transfusion, it does not offer identification of exact haemoglobin level at which regional oxygenation and perfusion gets compromised. Assessment of regional oxygenation using near infrared spectroscopy and perfusion using ultrasound could offer a personalized transfusion medicine approach to optimize transfusion practices. We conducted a systematic review of the literature to identify the role of both regional oxygenation and/or ultrasound-based perfusion monitoring as a potential trigger to initiate packed red blood cell transfusion in anaemic preterm infants. MEDLINE, Embase, Maternity and Infant Care database were searched up to March 2021. Publications identified were screened and relevant data was extracted. Changes to regional oxygenation and/or perfusion monitoring before and after packed red blood cell transfusion were the primary outcomes. 44 out of 755 studies met the inclusion criteria and were included in the final analysis. Most were prospective, observational studies in stable preterm infants. Overall, studies reported an improvement in regional oxygenation and/or ultrasound-based perfusion after packed red blood cell transfusion. These changes were more consistently observed when hemoglobin <9.6g/dL or hematocrit was <0.30. Significant variation was found for patient characteristics, postnatal age at the time of monitoring, criteria for diagnosis of anaemia, and period of monitoring as well as regional oxygenation monitoring methodology. Regional oxygenation and/or perfusion monitoring can identify at-risk anaemic preterm infants and are promising tools to individualize packed red blood cell transfusion practices. However, there is lack of evidence for incorporating this monitoring, in their present form, into standard clinical practice. Additionally, consistency in reporting of study methodology should be improved.

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.

A Preterm Physiologically Based Pharmacokinetic Model. Part I: Physiological Parameters and Model Building

BACKGROUND

Developmental physiology can alter pharmacotherapy in preterm populations. Because of ethical and clinical constraints in studying this vulnerable age group, physiologically based pharmacokinetic models offer a viable alternative approach to predicting drug pharmacokinetics and pharmacodynamics in this population. However, such models require comprehensive information on the changes of anatomical, physiological and biochemical variables, where such data are not available in a single source.

OBJECTIVE

The objective of this study was to integrate the relevant physiological parameters required to build a physiologically based pharmacokinetic model for the preterm population.

METHODS

Published information on developmental preterm physiology and some drug-metabolising enzymes were collated and analysed. Equations were generated to describe the changes in parameter values during growth.

RESULTS

Data on organ size show different growth patterns that were quantified as functions of bodyweight to retain physiological variability and correlation. Protein binding data were quantified as functions of age as the body weight was not reported in the original articles. Ontogeny functions were derived for cytochrome P450 1A2, 3A4 and 2C9. Tissue composition values and how they change with age are limited.

CONCLUSIONS

Despite the limitations identified in the availability of some tissue composition values, the data presented in this article provide an integrated resource of system parameters needed for building a preterm physiologically based pharmacokinetic model.

Bioreactance-derived haemodynamic parameters in the transitional phase in preterm neonates: a longitudinal study

Bioreactance (BR) is a novel, non-invasive technology that is able to provide minute-to-minute monitoring of cardiac output and additional haemodynamic variables. This study aimed to determine the values for BR-derived haemodynamic variables in stable preterm neonates during the transitional period. A prospective observational study was performed in a group of stable preterm (< 37 weeks) infants in the neonatal service of Tygerberg Children's Hospital, Cape Town, South Africa. All infants underwent continuous bioreactance (BR) monitoring until 72 h of life. Sixty three preterm infants with a mean gestational age of 31 weeks and mean birth weight of 1563 g were enrolled. Summary data and time series graphs were drawn for BR-derived heart rate, non-invasive blood pressure, stroke volume, cardiac output and total peripheral resistance index. All haemodynamic parameters were significantly associated with postnatal age, after correction for clinical variables (gestational age, birth weight, respiratory support mode). To our knowledge, this is the first paper to present longitudinal BR-derived haemodynamic variable data in a cohort of stable preterm infants, not requiring invasive ventilation or inotropic support, during the first 72 h of life. Bioreactance-derived haemodynamic monitoring is non-invasive and offers the ability to simultaneously monitor numerous haemodynamic parameters of global systemic blood flow. Moreover, it may provide insight into transitional physiology and its pathophysiology.

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.

Early Role of the Atrial-Level Communication in Premature Infants with Patent Ductus Arteriosus

BACKGROUND

High-volume systemic-to-pulmonary ductus arteriosus shunts in premature infants are associated with adverse neonatal outcomes. The role of an atrial communication (AC) in modulating the effects of a presumed hemodynamically significant patent ductus arteriosus (PDA) is poorly studied. The objective of this study was to characterize the relationship between early AC and echocardiographic indices of PDA shunt volume and clinical neonatal outcomes.

METHODS

A retrospective review of preterm infants (born at <32 weeks' gestation) who underwent echocardiography in the first postnatal week was performed. The cohort was divided into four groups on the basis of presence of a presumed hemodynamically significant PDA (≥1.5 vs <1.5 mm) and AC size (≤1 vs >1 mm), and echocardiographic measures of PDA shunt volume were then compared. Clinical outcomes, including chronic lung disease and intraventricular hemorrhage, were also compared among all four groups.

RESULTS

A total of 199 preterm infants (mean birth weight, 928 ± 632 g; mean gestational age, 26.6 ± 1.5 weeks) were identified; 159 infants had PDAs ≥ 1.5 mm, of whom 52 had ACs ≤ 1 mm and 107 had ACs > 1 mm. The remaining 40 infants had PDAs < 1.5 mm, of whom 23 had ACs ≤ 1 mm and 17 had ACs > 1 mm. Infants with PDAs ≥ 1.5 mm and ACs > 1 mm had higher pulmonary vein D-wave velocities (P < .05), higher left ventricular output (P < .005), higher PDA scores (P < .001), and increased rates of reversed diastolic flow in the descending aorta (P < .001), celiac artery (P < .001), and middle cerebral artery (P < .001) than infants with either PDAs < 1.5 mm or PDAs ≥ 1.5 mm and ACs ≤ 1 mm. There was no difference in the incidence of intraventricular hemorrhage, but infants with PDAs ≥ 1.5 mm and ACs > 1 mm had a higher risk for a composite outcome of chronic lung disease or death before hospital discharge (P < .05).

CONCLUSIONS

Echocardiographic evidence of ACs > 1 mm in patients with PDAs ≥ 1.5 mm during the first postnatal week may be a marker of a more pathologic hemodynamically significant PDA in premature infants. Future investigations should evaluate if early identification and treatment of patients with both high-volume PDAs and larger atrial-level communications may help mitigate adverse outcomes, such as chronic lung disease or death, in this high-risk patient population.

Hemodynamic effects of high-frequency oscillatory ventilation in preterm neonates with respiratory distress syndrome

BACKGROUND

High-frequency oscillatory ventilation (HFOV) can have negative hemodynamic effects in neonates. We aimed to assess systemic, cerebral, and cardiac hemodynamic changes in preterm neonates with respiratory distress syndrome (RDS) on HFOV.

METHODS

This observational study was conducted from June 2017 until May 2019 on 100 preterm neonates with RDS that needed switching from conventional mechanical ventilation to HFOV. Initial and Follow up capillary blood gas, echocardiographic examination, cranial ultrasound, and Doppler study of cerebral, celiac, superior mesenteric, and renal arteries using resistive index (RI) were performed before, 24 h, and 72 h after the use of HFOV.

RESULTS

There was no statistically significant difference as regards cardiac function, heart rate, or intraventricular hemorrhage on follow up measurements. However blood pressure, left ventricular dimensions, and volumes statistically increased after HFOV. There was a statistically significant decrease in the pulmonary artery systolic pressure after the use of HFOV. After the use of HFOV, there was a statistically significant increase in the superior vena cava flow and left ventricular output while right ventricular output values initially increased then slightly decreased but still higher than the initial values. RI of cerebral, superior mesenteric, celiac, and renal arteries significantly decreased on follow up measurements which reflected increased blood flow in these arteries.

CONCLUSION

HFOV had no negative effect on the cerebral, systemic, or cardiac hemodynamics when applied at optimum MAP. Therefore, concerns about negative hemodynamic effects of HFOV should not discourage the use of HFOV when deemed clinically indicated provided the use of optimum MAP.

Bioreactance Cardiac Output Trending Ability in Preterm Infants: A Single Centre, Longitudinal Study

INTRODUCTION

It is unknown whether bioreactance (BR) can accurately track cardiac output (CO) changes in preterm neonates.

METHODS

A prospective observational longitudinal study was performed in stable preterm infants (<37 weeks) during the first 72 h of life. Stroke volume (SV) and CO, as measured by BR and transthoracic echocardiography, were compared.

RESULTS

The mean gestational age (GA) was 31.3 weeks and mean birth weight (BW) was 1,563 g. Overall, 690 measurements were analysed for trending ability by 4-quadrant and polar plots. For non-weight-indexed measurements, 377 (54.6%) lay outside the 5% exclusion zone, the concordance rate was poor (77.2%) with a high mean angular bias (28.6°), wide limits of agreement and a poor angular concordance rate (17.4%). Neither GA, BW nor respiratory support mode affected trending data. Patent ductus arteriosus, postnatal age, and CO level had variable effects on trending data. Trending data for 5 and 10% exclusion zones were also compared.

CONCLUSION

The ability of BR to track changes in CO is not interchangeable with CO changes as measured by echocardiography. BR, as a trend monitor for changes in CO or SV to determine clinical decisions around interventions in neonatology, should be used with caution.

Low cardiac output measured by bioreactance and adverse outcome in preterm infants with birth weight less than 1250 g

BACKGROUND

Recently a new continuous non-invasive cardiac output measurement, bioreactance, has become available. Bioreactance measurement of cardiac output has been shown to correlate with left ventricular output detected by echocardiography in healthy term and preterm neonates.

AIMS

Our aim was to correlate cardiac output measurements by bioreactance in the first 48 h of life with adverse outcomes attributable to hypoperfusion (peri/intraventricular haemorrhage (PIVH) and/or necrotising enterocolitis (NEC)) in the cohort of extremely preterm infants.

STUDY DESIGN

A prospective observational cohort study.

SUBJECTS

Preterm infants with birth weight less than 1250 g.

OUTCOME MEASURES

Cardiac output was measured between six and 48 h of age by bioreactance. Our primary outcome was a difference in cardiac output between infants with an adverse outcome attributable to hypoperfusion (Group 1), and infants without the predefined adverse outcome (Group 2).

RESULTS

There were 39 infants enrolled in the study. There were six infants in Group 1. These infants had a significantly lower minimal cardiac output measurement compared to Group 2 (mean 36.7 ml/kg/min vs 64.5 ml/kg/min, p = .0006). The mean cardiac output in Group 1 was significantly lower on day one of life, followed by a significant increase in cardiac output on day two of life compared to Group 2.

CONCLUSIONS

Infants with birth weight less than 1250 g and PIVH and/or NEC had significantly lower cardiac output compared to infants without these complications on day one of life. This low cardiac output was then followed by a significant increase on day two of life.

Population pharmacokinetics and pharmacodynamics of dobutamine in neonates on the first days of life

AIMS

To describe the pharmacokinetics (PK) and concentration-related effects of dobutamine in critically ill neonates in the first days of life, using nonlinear mixed effects modelling.

METHODS

Dosing, plasma concentration and haemodynamic monitoring data from a dose-escalation study were analysed with a simultaneous population PK and pharmacodynamic model. Neonates receiving continuous infusion of dobutamine 5-20 μg kg-1 min-1 were included. Left ventricular ejection fraction (LVEF) and cardiac output of right and left ventricle (RVO, LVO) were measured on echocardiography; heart rate (HR), mean arterial pressure (MAP), peripheral arterial oxygen saturation and cerebral regional oxygen saturation were recorded from patient monitors.

RESULTS

Twenty-eight neonates with median (range) gestational age of 30.4 (22.7-41.0) weeks and birth weight (BW) of 1618 (465-4380) g were included. PK data were adequately described by 1-compartmental linear structural model. Dobutamine clearance (CL) was described by allometric scaling on BW with sigmoidal maturation function of postmenstrual age (PMA). The final population PK model parameter mean typical value (standard error) estimates, standardised to median BW of 1618 g, were 41.2 (44.5) L h-1 for CL and 5.29 (0.821) L for volume of distribution, which shared a common between subject variability of 29% (17.2%). The relationship between dobutamine concentration and RVO/LVEF was described by linear model, between concentration and LVO/HR/MAP/cerebral fractional tissue oxygen extraction by sigmoidal Emax model.

CONCLUSION

In the postnatal transitional period, PK of dobutamine was described by a 1-compartmental linear model, CL related to BW and PMA. A concentration-response relationship with haemodynamic variables has been established.

Cardiac adaptation in asphyxiated infants treated with therapeutic hypothermia

BACKGROUND

Hypoxic ischemic encephalopathy (HIE) affects  one to two newborns per 1,000 live births and oftentimes involves multi-organ insult. The objectives were to assess the evolution of cardiac function in infants with HIE treated with therapeutic hypothermia using echocardiography (ECHO).

METHODS

Archived data during the period 2010-2016 was assessed. Amongst the infants with baseline ECHO assessments, a sub-cohort which had assessments in all the three phases (baseline/pre-active cooling [T1], cooling [T2] and rewarming [T3]) was analyzed separately.

RESULTS

Thirty three infants formed part of the overall cohort, the gestation and birthweight were 39.6 ± 1.6 weeks and 3306 ± 583 g, respectively. Baseline (T1) information noted impaired cardiac performance (right ventricle stroke volume 1.08 ± 0.04 ml/kg, fractional area change [FAC] 24 ± 0.5% and tricuspid annular peak systolic excursion [TAPSE] 7.46 ± 0.11mm). Serial information was available for 24 of 33 infants. Cardiac function improved significantly between the cooling and the re-warming kphases. This included changes in right ventricular output (127 ± 34 vs 164 ± 47 ml/kg/min, p <0.01) and FAC (20 ± 3 vs 28 ± 2%, p<0.01). Pairwise comparisons for fractional shortening did not show significant changes. From the cooling to the rewarming phase, maximum change was noted in FAC (26.3 ± 9.8%) while minimum change was noted in fractional shortening (median, interquartile range) of 4.6% (1.4, 9.1). Significant correlation between TAPSE and time to peak velocity as a proportion of right ventricular ejection time was noted (r2 = 0.68, p <0.001).

CONCLUSIONS

In infants with moderate to severe HIE, cardiac function evolves during various phases of therapeutic hypothermia. Low output state during cooling may be due to a combination of the disease state (HIE) and cooling therapy.

Non-invasive Cardiac Output Monitoring in Neonates

Circulatory monitoring is currently limited to heart rate and blood pressure assessment in the majority of neonatal units globally. Non-invasive cardiac output monitoring (NiCO) in term and preterm neonates is increasing, where it has the potential to enhance our understanding and management of overall circulatory status. In this narrative review, we summarized 33 studies including almost 2,000 term and preterm neonates. The majority of studies evaluated interchangeability with echocardiography. Studies were performed in various clinical settings including the delivery room, patent ductus arteriosus assessment, patient positioning, red blood cell transfusion, and therapeutic hypothermia for hypoxic ischemic encephalopathy. This review presents an overview of NiCO in neonatal care, focusing on technical and practical aspects as well as current available evidence. We discuss potential goals for future research.

Respiratory distress syndrome: influence of management on the hemodynamic status of ≤ 32-week preterm infants in the first 24 hours of life

Objective

To investigate the influence of respiratory distress syndrome management on clinical and echocardiographic parameters used for hemodynamic evaluation in ≤ 32- week newborns.

Methods

Thirty-three ≤ 32-week newborns were prospectively evaluated and subjected to invasive mechanical ventilation. The need for exogenous surfactant and clinical and echocardiographic parameters in the first 24 hours of life was detailed in this group of patients.

Results

The mean airway pressure was significantly higher in newborn infants who required inotropes [10.8 (8.8 - 23) cmH₂O versus 9 (6.2 - 12) cmH₂O; p = 0.04]. A negative correlation was found between the mean airway pressure and velocity-time integral of the pulmonary artery (r = -0.39; p = 0.026), right ventricular output (r = -0.43; p = 0.017) and measurements of the tricuspid annular plane excursion (r = -0.37; p = 0.036). A negative correlation was found between the number of doses of exogenous surfactant and the right ventricular output (r = -0.39; p = 0.028) and pulmonary artery velocity-time integral (r = -0.35; p = 0.043).

Conclusion

In ≤ 32-week newborns under invasive mechanical ventilation, increases in the mean airway pressure and number of surfactant doses are correlated with the worsening of early cardiac function. Therefore, more aggressive management of respiratory distress syndrome may contribute to the hemodynamic instability of these patients.

Ductal size indexed to weight and body surface area correlates with morbidities in preterm infants ≤32 weeks

OBJECTIVES

To assess ductal size correlated to spontaneous closure, pharmacological or surgical treatment; to index ductal diameter to body weight and body surface area; to evaluate the morbidities.

STUDY DESIGN

Retrospective study on preterms ≤32 weeks, birth weight ≤1500 g, extremely low birth weight (ELBW) and very low birth weight (VLBW). Inclusion criteria: patent ductus arteriosus (PDA) with a diameter ≥1 millimeter (mm) at 72 h from birth; need for ibuprofen treatment on the basis of a hemodynamically significant ductus arteriosus (HsPDA).

RESULTS

One hundred infants with the diagnosis of PDA have been included. We observed a prevalence of spontaneous closure in 34% of newborns (41.3% VLBW versus 26.7% ELBW). The percentage of response to a single course of ibuprofen was of 62% (68.5% ELBW versus 54.3% VLBW). The mean of absolute ductal diameter was of 2.26 ± 0.62 mm in ELBW and 2.18 ± 0.42 mm in VLBW. The indexing of ductus size to body weight demonstrated a higher value in ELBW than VLBW (2.76 ± 0.97 mm/kg versus 1.84 ± 0.40 mm/kg).

CONCLUSIONS

Our results confirmed that HsPDA can develop in presence of a ductus >1.5 mm as absolute value or >1.4 mm/kg as indexed to body weight. In ELBW infants the ductal size indexed for body weight and body surface area could be more predictive of spontaneous closure or need for pharmacological treatment compared to the absolute value of ductal size. A strong association between HsPDA and short- or long-term morbidities was confirmed particularly in ELBW.

Changes in hemodynamics, cerebral oxygenation and cerebrovascular reactivity during the early transitional circulation in preterm infants

BACKGROUND

Changes in systemic and cerebral hemodynamics in preterm infants during early transitional circulation are complex and may differ between infants with or without intraventricular hemorrhage (IVH).

METHOD

In total, 43 infants born at median (range) 25 + 5 (23 + 3-31) had continuous near-infrared spectroscopy (NIRS) monitoring of tissue oxygenation index (TOI) and cerebrovascular reactivity within the first 48 h of life. Measurements of left and right cardiac outputs (LVO, RVO) and patent ductus arteriosus (PDA) were collected at 6, 12, 24, and 48 h of life.

RESULTS

LVO increased within the first 48 h in the IVH (P = 0.007) and no-IVH (P < 0.001) groups. The pattern of change in LVO and RVO was not different between these two groups. TOI was lower in the IVH (P < 0.001) group. A positive correlation between TOI and LVO (P = 0.003) and a negative correlation between the tissue oxygen reactivity index (TOx) and LVO (P = 0.04) were observed at 24 h of life in the IVH group. PDA diameter was not different between IVH groups at any time interval.

CONCLUSION

Cerebral oxygenation was lower and cerebrovascular reactivity was passive to systemic blood flow at 24 h in infants who developed an IVH.

Associations of measures of systemic blood flow used in a randomized trial of delayed cord clamping in preterm infants

OBJECTIVE

To determine associations of low superior vena cava (SVC) flow (≤55 ml/kg/min) and low right ventricular output (RVO) (≤150 ml/kg/min) in preterm infants.

DESIGN/METHODS

An observational study in infants <30 weeks gestation randomized to receive immediate (<10 s) or delayed cord clamping (DCC) (≥60 s).

RESULTS

The study enrolled 265 infants with a mean (SD) gestation 28 (2) weeks. Eighty-six (33%) infants had low SVC flow and 81 (31%) infants had low RVO. In multivariate analysis, low SVC flow was associated with gestation; low RVO was associated with DCC, gender and 5-minute Apgar; whereas mean RVO was negatively associated with both FiO₂ and mean airway pressure (MAP) at 9 h and 24 h. Low SVC flow was associated with ductus arteriosus (DA) treatment. Infants with low RVO had higher mortality on univariate analysis, but this was not significant after adjusting for gestation.

CONCLUSIONS

SVC flow was associated with gestation, whilst RVO was associated with placental transfusion, gender, condition at birth, and early respiratory adaptation. Compared to infants with normal values, more infants with low SVC flow were treated for DA, but infants with low RVO had no significant difference in mortality or morbidity.

Cord milking versus immediate clamping in preterm infants: a randomised controlled trial

OBJECTIVE

To investigate whether umbilical cord milking (UCM) at birth improves systemic blood flow and short-term outcomes, as compared with immediate cord clamping (ICC).

DESIGN

Randomised clinical trial.

SETTING

Single tertiary care centre.

PATIENTS

Infants born to eligible women presenting in preterm labour between 24 and 31 weeks' gestation.

INTERVENTIONS

UCM three times at birth or ICC.

OUTCOME MEASURES

Primary outcome included systemic blood flow as represented by echo-derived superior vena cava(SVC) flow at 4-6 hours after birth. The echocardiographer and interpreter were blinded to the randomisation. Secondary outcomes included cardiac output, neonatal morbidities and mortality. Analysis was by intention to treat.

RESULTS

A total of 73 infants were randomised (37 to UCM and 36 to ICC). Mean (SD) gestational age was 27 (2) weeks and mean (SD) birth weight was 1040 (283) g. Haemoglobin on admission was higher in the UCM than in the ICC group (16.1 vs 15.0 g/L), p=0.049 (mean difference 1.1, 95% CI 0.003 to 2.2). No statistically significant differences were found between groups in SVC flow at 4-6 hours (88.9±37.8 and 107.3±60.1 mL/kg/min), p=0.13 (mean difference -18.4, 95% CI -41.7 to 5.0 mL/kg/min) or at 10-12 hours of age (102.5±41.8 and 90.6±28.4 mL/kg/min), p=0.17 (mean difference 12.0, 95% CI -4.7 to 28.7 mL/kg/min), cardiac output or neonatal morbidities.

CONCLUSIONS

Cord milking was not shown to improve functional cardiac outcomes, neonatal morbidity or mortality. More research is needed before routine cord milking can be recommended for very preterm infants.

TRIAL REGISTRATION

NCT01487187.

Cardiac Output Measurement Using the Ultrasonic Cardiac Output Monitor: A Validation Study in Newborn Infants

OBJECTIVES

We aimed to determine the accuracy and validity of the Ultrasonic Cardiac Output Monitor (USCOM) measurements of cardiac output (CO) compared to echocardiography in newborn infants, and the inter-rater agreement of USCOM measurements.

METHODS

In a single-center study we prospectively evaluated neonates undergoing an echocardiographic evaluation. USCOM measurements of CO were obtained at the pulmonary and aortic valve by 2 physicians blinded to the echocardiographic results. All echocardiographic measurements were performed blinded to USCOM measurements. We first enrolled an ascertainment cohort which was subsequently validated in an independent new cohort. Agreement between echocardiography and USCOM methods was assessed by Bland-Altman analysis. Intra-class correlation coefficients (ICC) assessed the agreement between the 2 operators. The ascertainment cohort correction factors were applied in a second validation cohort and agreement of the calibrated measures evaluated with repeat Bland-Altman comparisons.

RESULTS

A total of 50 infants were enrolled in the initial cohort and 15 in the validation cohort. There was a high degree of correlation between the USCOM operators (ICC = 0.975). USCOM measurements of CO were significantly higher compared to echocardiography (left ventricular output bias 95 ± 52 mL/kg/min and right ventricular output bias 64 ± 30 mL/kg/min). There was no difference in the subgroup of infants with and without a ductus arteriosus. After the correction was applied to the validation cohort, there was no longer a significant difference between the measures.

CONCLUSIONS

CO measured by USCOM consistently overestimated the results obtained from echocardiography. USCOM is not adequate to provide absolute estimates of CO. However, it may allow longitudinal hemodynamic assessment of sick neonates.

Monitoring and management of brain hemodynamics and oxygenation

While cardiorespiratory monitoring is standard for newborns in the NICU, monitoring of brain hemodynamics and oxygenation is usually sporadic and targeted to newborns with suspected or confirmed neurologic disorders. This is unfortunate, since critically ill newborns, both preterm and term-born, are at high risk of brain injury and would benefit from improved techniques for continuous monitoring of brain hemodynamics and oxygenation, in addition to monitoring of systemic hemodynamics and oxygenation. Near-infrared spectroscopy (NIRS) and, to a lesser extent, Doppler ultrasound are techniques that have been used in research and increasingly for clinical purposes to measure and monitor brain hemodynamics and oxygenation in newborns. NIRS monitoring can be useful for detection of diverse pathologic conditions that occur frequently in very preterm newborns and in selected populations of term newborns at risk for brain injury related to disturbances of systemic hemodynamics. This chapter reviews the current state of the art with regard to brain-monitoring techniques and the research directed at this important area, and it concludes with suggestions for the use of currently available tools to manage newborns at high risk of neurologic injury from disturbances in brain hemodynamics and oxygenation.

Neonatal hemodynamics and management of hypotension in newborns

Hemodynamic instability is frequent in high-risk infants admitted to neonatal intensive care units. However, monitoring and treatment strategies of those conditions might show variations among the units. Different factors can compromise hemodynamic status in preterm/ term infants. Treatment options mostly include volume replacement, inotropes and/or vasopressors (dopamine, dobutamine, epinephrine and milrinone) and hydrocortisone. In general, these treatments are driven by predetermined protocols, which are not patient-based. According to the current knowledge, a physiology-driven approach that takes the individual characteristics of the newborn into consideration is accepted to be more suitable. In neonatal hemodynamics, important determinants are cardiac output, systemic vascular resistance, blood pressure, regional tissue perfusion and oxygenation. The novel technological methods, "targeted neonatal echocardiography" and "near-infrared spectroscopy" can help to delineate the underlying pathophysiology better, when added to the clinical assessment. In this review, strategies for the assessment of neonatal hemodynamics, as well as etiology, monitoring, and treatment of hemodynamic instability in preterm and term infants are presented.

Intra- and Inter-rater Agreement of Superior Vena Cava Flow and Right Ventricular Outflow Measurements in Late Preterm and Term Neonates

OBJECTIVES

To explore the intra- and inter-rater agreement of superior vena cava (SVC) flow and right ventricular (RV) outflow in healthy and unwell late preterm neonates (33-37 weeks' gestational age), term neonates (≥37 weeks' gestational age), and neonates receiving total-body cooling.

METHODS

The intra- and inter-rater agreement (n = 25 and 41 neonates, respectively) rates for SVC flow and RV outflow were determined by echocardiography in healthy and unwell late preterm and term neonates with the use of Bland-Altman plots, the repeatability coefficient, the repeatability index, and intraclass correlation coefficients.

RESULTS

The intra-rater repeatability index values were 41% for SVC flow and 31% for RV outflow, with intraclass correlation coefficients indicating good agreement for both measures. The inter-rater repeatability index values for SVC flow and RV outflow were 63% and 51%, respectively, with intraclass correlation coefficients indicating moderate agreement for both measures.

CONCLUSIONS

If SVC flow or RV outflow is used in the hemodynamic treatment of neonates, sequential measurements should ideally be performed by the same clinician to reduce potential variability.

Epinephrine versus dopamine in neonatal septic shock: a double-blind randomized controlled trial

We compared epinephrine and dopamine as a first-line vasoactive drug in 40 neonates (enrolled in two gestational age strata ≤ 30^6/7 and ≥ 31^0/7 weeks) with fluid-refractory septic shock. Epinephrine or dopamine was initiated at 0.2 or 10 μg/kg/min, respectively. If shock persisted after 15 min, epinephrine or dopamine was increased to 0.3 or 15 μg/kg/min, respectively (16-30 min), and thereafter to 0.4 or 20 μg/kg/min (31-45 min). Proportion of neonates achieving 'reversal of shock' (defined as systolic and diastolic BP > fifth centile and capillary filling time < 3 s and left ventricular output ≥ 150 mL/kg/min) by 45 min [5 (25%) vs 6 (30%), RR 0.83 (95% CI 0.30, 2.29)]; haemodynamic stability (shock reversal for ≥ 120 min without escalation of vasoactive drugs) anytime during therapy [10 (50%) vs 6 (30%), RR 1.67 (95% CI 0.75, 3.71)]; and all-cause mortality by 28 days [14 (70%) vs 16 (80%), RR 0.87 (95% CI 0.61, 1.26)] were comparable in the epinephrine and dopamine groups, respectively. On stratified analysis, we observed an interaction of gestational age strata with the group of allocation favouring epinephrine in neonates ≤ 30^6/7 weeks.Conclusion: Epinephrine (0.2-0.4 μg/kg/min) and dopamine (10-20 μg/kg/min) had comparable efficacy and safety in neonatal septic shock.Clinical Trial registry name and registration number: The study was registered with Clinical Trial Registry of India CTRI/2015/10/006285. What is Known: • The choice of vasoactive drugs in neonatal septic shock is empirical and dopamine is the conventional first-line vasoactive drug. • There are no randomized controlled trials comparing dopamine and epinephrine in neonatal septic shock. What is New: • In this study, epinephrine and dopamine had comparable efficacy and safety as a first-line vasoactive drug in management of neonatal septic shock. • On stratified analysis in a limited sample, epinephrine was associated with better outcomes in neonates ≤ 30^6/7 weeks.

The role of Neonatologist Performed Echocardiography in the assessment and management of neonatal shock

One of the major challenges of neonatal intensive care is the early detection and management of circulatory failure. Routine clinical assessment of the hemodynamic status of newborn infants is subjective and inaccurate, emphasizing the need for objective monitoring tools. An overview will be provided about the use of neonatologist-performed echocardiography (NPE) to assess cardiovascular compromise and guide hemodynamic management. Different techniques of central blood flow measurement, such as left and right ventricular output, superior vena cava flow, and descending aortic flow are reviewed focusing on methodology, validation, and available reference values. Recommendations are provided for individualized hemodynamic management guided by NPE.