A review of superior vena cava flow measurement in the neonate by functional echocardiography

Educational Impact of Targeted Neonatal Echocardiography and Hemodynamics Programs on Neonatal-Perinatal Medicine Fellows

OBJECTIVE

 Targeted neonatal echocardiography (TNE) is a real-time cardiac imaging modality used by a hemodynamics program to aid in diagnosis, treatment, and monitoring of neonatal cardiovascular illness. This study aimed to describe trainees' perspectives on existing hemodynamics education and perceived impacts of TNE and hemodynamics services on their education.

STUDY DESIGN

 This was a mixed quantitative and qualitative study that surveyed neonatal-perinatal medicine (NPM) fellow trainees in Canada and the United States, at programs both with and without a hemodynamics service.

RESULTS

 Ninety-two fellows responded to the survey, of whom 24 (26%) were enrolled in a program with an active hemodynamics service, 64 (70%) were training at a program without a hemodynamics service, and 4 (4%) were unsure. Trainees at centers with a hemodynamics service were more satisfied with their cardiovascular physiology education (91 vs. 69%, p = 0.040). Twenty-five percent of all trainees felt they do not have sufficient hemodynamics training to prepare them for independent practice. Areas of knowledge gaps were identified. Bedside teaching combined with didactic teaching was identified as useful means of teaching.

CONCLUSION

 Most trainees believed that TNE and a hemodynamics service are valuable educational assets. Thoughtful curriculum design for real-time and consolidation learning, with specific emphasis on content gaps, should be considered.

KEY POINTS

· NPM Fellows perceive TNE & Neonatal Hemodynamics service as a valuable educational opportunity.. · Incorporation of TNE/Hemodynamics teaching into NPM curriculum can enrich trainee experience.. · Combining bedside and classroom teaching is key to successful cardiovascular training..

Superior Vena Cava Flow in Preterm Infants and Neonatal Outcomes: A Systematic Review

Superior vena cava (SVC) flow has been considered a surrogate marker of systemic blood flow in neonates. We conducted a systematic review to evaluate the association between low SVC flow recorded during the early neonatal period and neonatal outcomes. We searched the following databases (until December 9, 2020; updated October 21, 2022): PROSPERO, OVID Medline, OVID EMBASE, Cochrane Library (CDSR and Central), Proquest Dissertations and Theses Global, and SCOPUS using controlled vocabulary and key words representing the concepts "superior vena cava" and "flow" and "neonate." Results were exported to COVIDENCE review management software. The search retrieved 593 records after the removal of duplicates, of which 11 studies (nine cohorts) met the inclusion criteria. The majority of the studies included infants born at <30 weeks of gestation. The included studies were assessed as high risk of bias in terms of the incomparability of the study groups, with infants in the low SVC flow group noted to be more immature than those in the normal SVC flow group or subjected to different cointerventions. We did not conduct meta-analyses in view of the significant clinical heterogeneity noted in the included studies. We found little evidence to suggest that SVC flow in the early neonatal period is an independent predictor for adverse clinical outcomes in preterm infants. Included studies were assessed at high risk of bias. We conclude that SVC flow interpretation for prognostication or for making treatment decisions should be restricted to the research setting for now. We highlight the need for strengthened methods in future research studies. KEY POINTS: · We studied whether low SVC flow in the early neonatal period is a marker for adverse outcomes in preterm infants.. · There is insufficient evidence to conclude that low SVC flow is a valid predictor of adverse outcomes.. · There is insufficient evidence to conclude that SVC flow-directed hemodynamic management improves clinical outcomes..

Should SVC flow be a routine measure when performing targeted neonatal echocardiography? A narrative review

Superior vena cava is commonly used in neonatal hemodynamics and is suggested to be the best available non-invasive marker for systemic circulation in preterm infants. Inter- and intra-observer variability remain to be an issue. Its association with neonatal outcomes is has not been established. This is a narrative review about this marker, its use, and its potential pitfalls.

OBJECTIVE

This is a narrative review about SVC flow in preterm infants, physiology, techniques of measurement and its potential association with outcomes.

SOURCES

Literature revie mainly PubMED.

SUMMARY OF THE FINDINGS

SVC flow measurement has some limitations and pitfalls.

CONCLUSIONS

SVC flow association with neonatal outcomes, still needs to be established in further research.

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.

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.

Diagnostic and predictive value of Doppler ultrasound for evaluation of the brain circulation in preterm infants: a systematic review

INTRODUCTION

Very and extremely preterm infants frequently have brain injury-related long-term neurodevelopmental problems. Altered perfusion, for example, seen in the context of a hemodynamically significant patent ductus arteriosus (PDA), has been linked to injury of the immature brain. However, a direct relation with outcome has not been reviewed systematically.

METHODS

A systematic review was conducted to provide an overview of the value of different cerebral arterial blood flow parameters assessed by Doppler ultrasound, in relation to brain injury, to predict long-term neurodevelopmental outcome in preterm infants.

RESULTS

In total, 23 studies were included. Because of heterogeneity of studies, a meta-analysis of results was not possible. All included studies on resistance index (RI) showed significantly higher values in subjects with a hemodynamically significant PDA. However, absolute differences in RI values were small. Studies using Doppler parameters to predict brain injury and long-term neurodevelopmental outcome were inconsistent.

DISCUSSION

There is no clear evidence to support the routine determination of RI or other Doppler parameters in the cerebral arteries to predict brain injury and long-term neurodevelopmental outcome in the preterm infant. However, there is evidence that elevated RI can point to the presence of a hemodynamically significant PDA.

Hemodynamics of neonatal double lumen cannula malposition

Objective:

Malposition of dual lumen cannula is a frequent and challenging complication in neonates and plays a significant role in shaping the in vitro device hemodynamics. This study aims to analyze the effect of the dual lumen cannula malposition on right-atrial hemodynamics in neonatal patients using an experimentally validated computational fluid dynamics model.

Methods:

A computer model was developed for clinically approved dual lumen cannula (13Fr Origen Biomedical, Austin, Texas, USA) oriented inside the atrium of a 3-kg neonate with normal venous return. Atrial hemodynamics and dual lumen cannula malposition were systematically simulated for two rotations (antero-atrial and atrio-septal) and four translations (two intravascular movements along inferior vena cava and two dislodged configurations in the atrium). A multi-domain compartmentalized mesh was prepared to allow the site-specific evaluation of important hemodynamic parameters. Transport of each blood stream, blood damage levels, and recirculation times are quantified and compared to dual lumen cannula in proper position.

Results:

High recirculation levels (39 ± 4%) in malpositioned cases resulted in poor oxygen saturation where maximum recirculation of up to 42% was observed. Apparently, Origen dual lumen cannula showed poor inferior vena cava blood–capturing efficiency (48 ± 8%) but high superior vena cava blood–capturing efficiency (86 ± 10%). Dual lumen cannula malposition resulted in corresponding changes in residence time (1.7 ± 0.5 seconds through the tricuspid). No significant differences in blood damage were observed among the simulated cases compared to normal orientation. Compared to the correct dual lumen cannula position, both rotational and translational displacements of the dual lumen cannula resulted in significant hemodynamic differences.

Conclusion:

Rotational or translational movement of dual lumen cannula is the determining factor for atrial hemodynamics, venous capturing efficiency, blood residence time, and oxygenated blood delivery. Results obtained through computational fluid dynamics methodology can provide valuable foresight in assessing the performance of the dual lumen cannula in patient-specific configurations.

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.

[Impact of screening and treatment of low systemic blood flow in the prevention of severe intraventricular haemorrhage and/or death in pre-term infants]

OBJECTIVE

To assess the effect of a protocolised intervention for low systemic blood flow (SBF) in the occurrence of severe intraventricular haemorrhage (IVH) or death in pre-term infants.

METHODS

A study with a quasi-experimental design with retrospective controls was conducted on pre-term infants of less than 30weeks of gestational age, born between January 2016 and July 2017, who were consecutively included in the intervention period. The control cohort included pre-term infants (born between January 2013 and December 2015) matched by gestational age, birth weight, and gender (two controls for each case). The cases of low SBF diagnosed according to functional echocardiography during the study period received dobutamine (5-10μg/kg/min) for 48hours.

RESULTS

The study included 29 cases (intervention period) and 54 controls (pre-intervention period). Ten out of 29 (34.5%) infants received dobutamine for low SBF during the intervention period, with 3/29 (10.3%) cases of severe IVH and/or death compared to 17/54 (31.5%) in the control cohort (p=.032). There was an independent association between the intervention and a decreased occurrence of severe IVH/death after adjusting for confounding factors both in the logistic regression model [OR 0.11 (95%CI: 0.01-0.65), p=.015], as well as in the sensitivity analysis using inverse probability of treatment weighting [OR 0.23 (95%CI: 0.09-0.56); p=.001].

CONCLUSIONS

In this study with retrospective controls, a protocolised screening, and treatment for low SBF was associated with a decreased occurrence of severe IVH or death in preterm infants. Large, adequately powered trials, are needed in order to determine whether postnatal interventions directed at low SBF can improve neurological outcomes.

Cardiac Output Monitoring in Preterm Infants

Maintaining optimal circulatory status is a key component of preterm neonatal care. Low-cardiac output (CO) in the preterm neonate leads to inadequate perfusion of vital organs and has been linked to a variety of adverse outcomes with heightened acute morbidity and mortality and adverse neurodevelopmental outcomes. Having technology available to monitor CO allows us to detect low-output states and potentially intervene to mitigate the unwanted effects of reduced organ perfusion. There are many technologies available for the monitoring of CO in the preterm neonatal population and while many act as useful adjuncts to aid clinical decision-making no technique is perfect. In this review, we discuss the relative merits and limitations of various common methodologies available for monitoring CO in the preterm neonatal population. We will discuss the ongoing challenges in monitoring CO in the preterm neonate along with current gaps in our knowledge. We conclude by discussing emerging technologies and areas that warrant further study.

Golden hour of neonatal life: Need of the hour

"Golden Hour" of neonatal life is defined as the first hour of post-natal life in both preterm and term neonates. This concept in neonatology has been adopted from adult trauma where the initial first hour of trauma management is considered as golden hour. The "Golden hour" concept includes practicing all the evidence based intervention for term and preterm neonates, in the initial sixty minutes of postnatal life for better long-term outcome. Although the current evidence supports the concept of golden hour in preterm and still there is no evidence seeking the benefit of golden hour approach in term neonates, but neonatologist around the globe feel the importance of golden hour concept equally in both preterm and term neonates. Initial first hour of neonatal life includes neonatal resuscitation, post-resuscitation care, transportation of sick newborn to neonatal intensive care unit, respiratory and cardiovascular support and initial course in nursery. The studies that evaluated the concept of golden hour in preterm neonates showed marked reduction in hypothermia, hypoglycemia, intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), and retinopathy of prematurity (ROP). In this review article, we will discuss various components of neonatal care that are included in "Golden hour" of preterm and term neonatal care.