Hemodynamics and Perfusion in Premature Infants During Transfusion

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.

Near-Infrared Spectroscopy to Guide and Understand Effects of Red Blood Cell Transfusion

This review is a summary of available evidence regarding the use of near-infrared spectroscopy (NIRS) to help better guide and understand the effects of red blood cell (RBC) transfusion in neonatal patients. We review recent literature demonstrating the changes that take place in regional tissue oxygen saturation (rSO2) resulting from RBC transfusion. We also discuss in detail if any correlation exists between rSO2 and hemoglobin values in neonates. Finally, we review studies that have evaluated the use of NIRS as a transfusion guide during neonatal intensive care.

Cerebral and splanchnic near-infrared spectroscopic dataset in premature newborns receiving packed red blood cell transfusion

This article presents the near-infrared spectroscopy (NIRS) dataset of cerebral (StO₂c) and splanchnic (StO₂s) oxygenation in 29 stable premature infants admitted to a tertiary neonatal intensive care unit who received elective packed red blood cell transfusion (PRBCT) to treat anemia of prematurity. StO₂c and StO₂s data were prospectively recorded continuously from at least 4 hours before the beginning of PRBCT until 24 hours after its completion, using a 4-wavelength near-infrared spectroscopy (NIRS) monitor (FORE-SIGHT® absolute cerebral oximeter, CASMED, Branford, Connecticut, 06405 USA). StO₂ data were downloaded as an analog output at a sampling rate of 1000Hz and aligned along the time axis in LabChart reader format (.adicht files) using a PowerLab data acquisition system [1] (PowerLab®, ADInstruments, Sydney, Australia). The .adicht files were then converted into .mat file format using a Python script (Python^TM version 3.7.3 [2]) and resampled at 1Hz for faster processing. Data that could not be physiologically explained (e.g., the absence of variability, [3] a 30% step change in StO₂ between two subsequent data points for StO₂[4]), as well as the data during the period of 'cares' were presumed to be artefactual and were replaced with 'NaN' or 'Not a Number' which is recognised by Matlab [5] (MATLAB 9.3, The MathWorks, Inc., Massachusetts, United States) and ignored for all subsequent processing while maintaining the correct time point of the StO₂ signals. The data were then exported into Microsoft Excel format. The splanchnic cerebral oxygenation ratio (SCOR) was calculated as the ratio of StO₂s/StO₂c. A 4-hour mean pre-transfusion values (StO₂s 0, StO₂c 0, SCOR 0) and post-transfusion hourly mean values (1-28) were determined. Secondary data were derived from a Mixed Models for Repeated Measures (MMRM) analysis with the time point fitted as a fixed effect and the infant fitted as a random effect. The MMRM was used to perform paired comparisons between pre-transfusion and each of the post-baseline values. This article only provides the NIRS data. The secondary data and demography can be found in the article "Splanchnic-Cerebral Oxygenation Ratio associated with Packed Red Blood Cell Transfusion in preterm infants", published in Transfusion Medicine. [6] The data will be of use to researchers in neonatology, transfusion medicine, and physiology to understand changes in cerebral and splanchnic oxygenation associated with PRBCT. Data collection, processing, and analysis can be remodelled in larger multicentric randomised controlled studies to evaluate the effect of transfusion and feeding on transfusion-associated necrotising enterocolitis. The data are also helpful to explore the autoregulatory behaviour of the brain and gut when the oxygen content of blood is increased by administering PRBCT.

Splanchnic-cerebral oxygenation ratio associated with packed red blood cell transfusion in preterm infants

BACKGROUND

Splanchnic-cerebral oxygenation ratio (SCOR), the ratio of splanchnic tissue oxygen (StO₂ s) to simultaneously measured cerebral tissue oxygen (StO₂ c), has been described as a surrogate to detect impaired splanchnic oxygenation associated with hypoperfusion status such as necrotizing enterocolitis. This concept is based on the presumption that any change in SCOR indicates a corresponding change in splanchnic tissue oxygenation as the numerator, whereas cerebral tissue oxygenation as the denominator remains stable. However, it is questionable to utilise this concept to detect splanchnic oxygenation changes in the context of packed red blood cell transfusion (PRBCT).

AIM

The current study examines the contribution of both cerebral and splanchnic oxygenation components to PRBCT-associated SCOR changes in preterm infants.

DESIGN

Prospective cohort study.

SETTING

Neonatal intensive care.

PATIENTS

Hemodynamically stable infants: Gestation <32 weeks; birth weight <1500 g; postmenstrual age <37 weeks: tolerating ≥120 ml/kg/day feed volume.

INTERVENTIONS

PRBCT at 15 ml/kg, over 4 h.

MAIN OUTCOME MEASURES

Transfusion-associated changes were determined by performing mixed models for repeated measures analysis between the 4-h mean pre-transfusion values (SCOR 0, StO₂ s 0, and StO₂ c 0) and the post-transfusion hourly mean values for the next 28 h (SCOR 1-28, StO₂ s 1-28, and StO₂ c 1-28). Dunnett's method was used to adjust for the multiplicity of the p value.

RESULTS

Of 30 enrolled infants 14 [46.7%] male; median [IQR] birth weight, 923 [655-1064] g; gestation, 26.4 [25.5-28.1] weeks; enrolment weight, 1549 [1113-1882] g; and postmenstrual age, 33.6 [32.4-35.0] weeks, one infant was excluded because of corrupted NIRS data. With the commencement of PRBCT, SCOR demonstrated a downward trend throughout the study period. This drift was associated with an increasing StO₂ c trend, while StO₂ s remained unchanged throughout the study period.

CONCLUSIONS AND RELEVANCE

PRBCT-associated SCOR decrease suggests improvement in cerebral oxygenation rather than worsening splanchnic oxygenation. Our study underlines that it is necessary to determine individual components of SCOR, namely cerebral and splanchnic StO₂ to understand SCOR changes in the context of PRBCT.

Hierarchical improvement of regional tissue oxygenation after packed red blood cell transfusion

Background

It is well established that counter-regulation to hypoxia follows a hierarchical pattern, with brain-sparing in preference to peripheral tissues. In contrast, it is unknown if the same hierarchical sequence applies to recovery from hypoxia after correction of anemia with packed red blood cell transfusion (PRBCT).

Objective

To understand the chronology of cerebral and splanchnic tissue oxygenation resulting after correction of anemia by PRBCT in preterm infants using near-infrared spectroscopy (NIRS).

Design

Prospective cohort study.

Setting

Neonatal intensive care.

Patients included

Haemodynamically stable infants: <32 weeks gestation, <37weeks postmenstrual age, <1500 grams birth weight; and ≥120 mL/kg/day feeds tolerated.

Intervention

PRBCT at 15 mL/Kg over 4 hours.

Main outcome measures

Transfusion-associated changes were determined by comparing the 4-hour mean pre-transfusion cerebral and splanchnic fractional tissue oxygen extraction (FTOEc0; FTOEs0) with hourly means during (FTOEc1-4; FTOEs1-4) and for 24 hours after PRBCT completion (FTOEc5-28; FTOEs5-28).

Results

Of 30 enrolled infants, 14[46.7%] male; median[IQR] birth weight, 923[655–1064]g; gestation, 26.4[25.5–28.1]weeks; enrolment weight, 1549[1113–1882]g; and postmenstrual age, 33.6[32.4–35]weeks, 1 infant was excluded because of corrupted NIRS data. FTOEc significantly decreased during and for 24 hours after PRBCT (p < 0.001), indicating prompt improvement in cerebral oxygenation. In contrast, FTOEs showed no significant changes during and after PRBCT (p>0.05), indicating failure of improvement in splanchnic oxygenation.

Conclusion

Improvement in regional oxygenation after PRBCT follows the same hierarchical pattern with a prompt improvement of cerebral but not splanchnic tissue oxygenation. We hypothesise that this hierarchical recovery may indicate continued splanchnic hypoxia in the immediate post-transfusion period and vulnerability to transfusion-associated necrotizing enterocolitis (TANEC). Our study provides a possible mechanistic underpinning for TANEC and warrants future randomised controlled studies to stratify its prevention.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

Feeding Practices and Effects on Transfusion-Associated Necrotizing Enterocolitis in Premature Neonates

BACKGROUND

Red blood cell (RBC) transfusions have been implicated in the development of necrotizing enterocolitis (NEC) in premature infants. Some evidence exists to support that withholding feedings during transfusion reduces the risk of subsequent NEC development.

PURPOSE

To review the most recent literature on this topic to determine best evidence-based practice regarding withholding or not withholding feedings during RBC transfusions.

METHODS/SEARCH STRATEGY

Four databases were searched using keywords and MeSH terms including "necrotizing enterocolitis," "NEC," "NPO," and "transfusion," with specifications limiting the search to articles published in the last 10 years and limiting the population to neonates.

FINDINGS

Four studies did not demonstrate a reduction in transfusion-associated necrotizing enterocolitis (TANEC) with the implementation of feeding protocols during packed red blood cell (PRBC) transfusions. One study concluded that it could not confirm the benefit of withholding feeds during transfusion to reduce the risk of TANEC. A 2020 randomized controlled trial (RCT) found no difference in splanchnic oxygenation when enteral feeds are withheld, continued, or restricted during a PRBC transfusion. Holding feedings during PRBC transfusions did not result in adverse nutritional outcomes.

IMPLICATIONS FOR PRACTICE

To determine best evidence-based practice surrounding feeding protocols during RBC transfusions in very low-birth-weight and premature infants less than 37 weeks' gestation.

IMPLICATIONS FOR RESEARCH

It is recommended that large, multicentered, adequately powered RCTs be conducted in this area. Individual institutions should standardize their practice to improve quality, safety, and patient outcomes.

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.

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.

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.

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.