Haemodynamic Transition after Birth: A New Tool for Non-Invasive Cardiac Output Monitoring

Cardiac output calculation using the Liljestrand and Zander formula: is this method applicable during immediate transition after birth? - A post hoc analysis

The transition from intrauterine to extrauterine life is a critical period for neonates. Assessing the cardiovascular transition during this period immediately after birth is crucial but challenging. The present study compares adjusted estimated cardiac output values calculated by the Liljestrand and Zander formula (COest/adj LaZ) with non-invasively measured cardiac output values (CO-bioimpedance) during immediate transition after birth. We performed a secondary outcome analysis of a prospective observational study in preterm and term neonates. Ten and 15 min after birth, arterial blood pressure and heart rate were assessed, and CO-bioimpedance was measured using electrical bioimpedance method (Aesculon monitor, Osypka, Germany). We calculated COest/adj LaZ and compared it to CO-bioimpedance. Further, we performed a correlation analysis. Thirty-two neonates with a median (IQR) gestational age of 37.0 (32.0-39.4) weeks were included. Mean ± SD CO-bioimpedance was 0.62 ± 0.15 l/min, and COest/adj LaZ was calculated to be 0.64 ± 0.10 l/min, whereby both correlated significantly (p = 0.025, r = 0.359) with each other.  Conclusion: The present study demonstrates high comparability of COest/adj LaZ and CO-bioimpedance in neonates during immediate transition after birth, suggesting that cardiac output can be derived in a cost-effective and feasible manner if other methods are not available. What is Known: • Echocardiography is considered the gold standard for non-invasive CO evaluation, but its feasibility during the immediate transition period is limited. What is New: • Non-invasive methods such as CO-bioimpedance for cardiac output (CO) measurement and the Liljestrand and Zander (LaZ) formula for estimating CO offer promising alternatives during the immediate transition period.

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.

Cardiac output and regional-cerebral-oxygen-saturation in preterm neonates during immediate postnatal transition: An observational study

AIM

To examine potential correlations between cardiac output (CO) with cerebral-regional-oxygen-saturation (crSO₂ ) and cerebral-fractional-tissue-oxygen-extraction (cFTOE) during immediate foetal-to-neonatal transition in term and preterm neonates with and without respiratory support.

METHODS

Post hoc analyses of secondary outcome parameters of prospective observational studies were performed. We included neonates with cerebral near-infrared-spectroscopy (NIRS) monitoring and an oscillometric blood pressure measurement at minute 15 after birth. Heart rate (HR) and arterial oxygen saturation (SpO₂ ) were monitored. CO was calculated with Liljestrand and Zander formula and correlated with crSO₂ and cFTOE.

RESULTS

Seventy-nine preterm neonates and 207 term neonates with NIRS measurements and calculated CO were included. In 59 preterm neonates (mean gestational age (GA): 29.4 ± 3.7 weeks) with respiratory support, CO correlated significantly positively with crSO₂ and significantly negatively with cFTOE. In 20 preterm neonates (GA 34.9 ± 1.3 weeks) without respiratory support and in 207 term neonates with and without respiratory support, CO correlated neither with crSO₂ nor with cFTOE.

CONCLUSION

In compromised preterm neonates with lower gestational age and in need of respiratory support, CO was associated with crSO₂ and cFTOE, whereas in stable preterm neonates with higher gestational age as well as in term neonates with and without respiratory support, no associations were observed.

Neonatal Septic Shock and Hemodynamic Monitoring in Preterm Neonates in an NICU: Added Value of Electrical Cardiometry in Real-Time Tailoring of Management and Therapeutic Strategies

OBJECTIVE

Electrical cardiometry is an impedance-based monitoring technique that provides data on several hemodynamic parameters in a noninvasive way. There is limited information on clinical utility of the application of this technique in neonates.

STUDY DESIGN

In this study, we describe the case of a preterm neonate born at 30^2/7 weeks of gestational age who developed severe systemic infection with fluid refractory septic shock on day 2 of life.

DISCUSSION

Electrical cardiometry was used and proved very helpful in real-time guiding the choice and the dosing of the most appropriate inotrope drugs in this patient. In addition, it promptly underlined an abrupt drop of systemic vascular resistances occurring after administration of the first dose of antibiotic, thus warning the attending neonatologist to institute appropriate treatment before the clinical conditions could further worsen.

CONCLUSION

This case report suggests that electrical cardiometry could be a useful tool in assessing, monitoring, and guiding care of neonates who develop severe septic shock. We suggest that electrical cardiometry is a promising approach in the management strategies of such patients that warrants informative clinical trials.

KEY POINTS

· Electrical cardiometry was helpful in real-time decision-making.. · Electrical cardiometry reported hemodynamic perturbations before worsening of clinical conditions.. · Electrical cardiometry should be included in the management of critical patients..

Accuracy and Trending Ability of Electrical Biosensing Technology for Non-invasive Cardiac Output Monitoring in Neonates: A Systematic Qualitative Review

BACKGROUND

Electrical biosensing technology (EBT) is an umbrella term for non-invasive technology utilizing the body's fluctuating resistance to electrical current flow to estimate cardiac output. Monitoring cardiac output in neonates may allow for timely recognition of hemodynamic compromise and allow for prompt therapy, thereby mitigating adverse outcomes. For a new technology to be safely used in the clinical environment for therapeutic decisions, it must be proven to be accurate, precise and be able to track temporal changes. The aim of this systematic review was to identify and analyze studies that describe the accuracy, precision, and trending ability of EBT to non-invasively monitor Left ventricular cardiac output and/or stroke volume in neonates.

METHODS

A qualitative systematic review was performed. Studies were identified from PubMed NCBI, SCOPUS, and EBSCOHost up to November 2021, where EBT technologies were analyzed in neonates, in comparison to a reference technology. Outcome measures were bias, limits of agreement, percentage error for agreement studies and data from 4-quadrant and polar plots for trending studies. Effect direction plots were used to present results.

RESULTS

Fifteen neonatal studies were identified, 14 for agreement and 1 for trending analysis. Only thoracic electrical biosensing technology (TEBT), with transthoracic echocardiography (TTE) as the comparator, studies were available for analyzes. High heterogeneity existed between studies. An equal number of studies showed over- and underestimation of left ventricular output parameters. All studies showed small bias, wide limits of agreement, with most studies having a percentage error >30%. Sub-analyses for respiratory support mode, cardiac anomalies and type of technology showed similar results. The single trending study showed poor concordance, high angular bias, and poor angular concordance.

DISCUSSION

Overall, TEBT shows reasonable accuracy, poor precision, and non-interchangeability with TTE. However, high heterogeneity hampered proper analysis. TEBT should be used with caution in the neonatal population for monitoring and determining therapeutic interventions. The use of TEBT trend monitoring has not been sufficiently studied and requires further evaluation in future trials.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Comparison of Cardiac Output Measurement by Electrical Velocimetry with Echocardiography in Extremely Low Birth Weight Neonates

INTRODUCTION

Electrical velocimetry (EV) offers a noninvasive tool for continuous cardiac output (CO) measurements which might facilitate hemodynamic monitoring and targeted therapy in low birth neonates, in whom other methods of CO measurement are not practicably feasible.

METHODS

This prospective observational study compared simultaneous cardiac output measurements by electrical velocimetry (COEV) with transthoracic echocardiography (COTTE) in extremely low birth weight (ELBW) neonates in the neonatal intensive care unit (NICU). Echocardiography was performed by 1 single examiner. Data were analyzed by Bland-Altman analysis and independent-samples analysis of variance. A mean percentage error (MPE) of <30% and limits of agreement (LOA) up to ±30% were considered clinically acceptable.

RESULTS

Thirty-eight ELBW neonates were studied and yielded 85 pairs of COEV and COTTE measurements. Bland-Altman analysis showed an overall bias (the mean difference) and LOA of -126 and -305 to +52 mL min-1, respectively, and an MPE of 66%. Patients with patent ductus arteriosus had a higher bias with LOA and MPE of -166.8, -370.7 to +37 mL min-1, and 69%, respectively. The overall true precision was 58%.

CONCLUSION

This study showed high bias and lack of agreement between EV and TTE for measurement of CO in ELBW infants in NICU, limiting applicability of EV to monitor absolute values.

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.

In-Silico Evaluation of Anthropomorphic Measurement Variations on Electrical Cardiometry in Neonates

Non-invasive cardiac output methods such as Electrical Cardiometry (EC) are relatively novel assessment tools for neonates and they enable continuous monitoring of stroke volume (SV). An in-silico comparison of differences in EC-derived SV in relation to preset length and weight was performed. EC (ICON, Osypka Medical) was simulated using the “demo” mode for various combinations of length and weight representative of term and preterm infants. One-centimetre length error resulted in a SV-change of 1.8–3.6% (preterm) or 1.6–2.0% (term) throughout the tested weight ranges. One-hundred gram error in weight measurement resulted in a SV-change of 5.0–7.1% (preterm) or 1.5–1.8% (term) throughout the tested length ranges. Algorithms to calculate EC-derived SV incorporate anthropomorphic measurements. Therefore, inaccuracy in physical measurement can impact absolute EC measurements. This should be considered in the interpretation of previous findings and the design of future clinical studies of EC-derived cardiac parameters in neonates, particularly in the preterm cohorts where a proportional change was noted to be greatest.

Feasibility of non-invasive cardiac output monitoring at birth using electrical bioreactance in term infants

BACKGROUND

Non-invasive cardiac output monitoring (NICOM) provides continuous estimation of cardiac output. This has potential for use in the delivery suite in the management of acutely depressed term infants. This study aims to measure cardiac output in term infants at delivery and in the first hours of life.

METHODS

Parents of term infants due to be born by elective caesarean section or vaginal delivery at Cork University Maternity Hospital, Ireland were approached in the antenatal period to participate. Cardiac output was measured using a CHEETAH NICOM device, which uses electrical bioreactance technology, at birth and at 2 hours of life.

RESULTS

Forty-nine newborns were included. The median gestational age was 39 (IQR: 39-40) weeks and the median birth weight was 3.50 (IQR: 3.14-3.91) kg. Cardiac output measurements were obtained at a median of 8 (IQR: 5-12) min of life. The mean (SD) cardiac output was 101 (24) mL/kg/min in the delivery room and 89 (22) mL/kg/min at 2 hours of life. There was a statistically significant decrease in cardiac output from birth to 2 hours of life (difference in mean (95% CI): 13.5 (9.2 to 17.9) mL/kg/min, p<0.001, n=47). There were no adverse effects associated with NICOM.

DISCUSSION

This technique is feasible and safe in the delivery room. Mean cardiac output measures using NICOM are lower than those found in studies which used echocardiography to determine cardiac output at birth.

Impact of bradycardia and hypoxemia on oxygenation in preterm infants requiring respiratory support at birth

AIM OF THE STUDY

Analysis of the impact of bradycardia and hypoxemia on the course of cerebral and peripheral oxygenation parameters in preterm infants in need for respiratory support during foetal-to-neonatal transition.

METHODS

The first 15 min after birth of 150 preterm neonates in need for respiratory support born at the Division of Neonatology, Graz (Austria) were analyzed. Infants were divided into different groups according to duration of bradycardia exposure (no Bradycardia, brief bradycardia <2 min, and prolonged bradycardia ≥2 min) and to systemic oxygen saturation (SpO₂) value at 5 min of life (<80% or ≥80%). Analysis was performed considering the degree of bradycardia alone (step 1) and in association with the presence of hypoxemia (step 2).

RESULTS

In step 1, courses of SpO₂ differed significantly between bradycardia groups (p = 0.002), while courses of cerebral regional oxygen saturation (crStO₂) and cerebral fractional tissue oxygen extraction (cFTOE) were not influenced (p = 0.382 and p = 0.878). In step 2, the additional presence of hypoxemia had a significant impact on the courses of SpO₂ (p < 0.001), crStO₂ (p < 0.001) and cFTOE (p = 0.045).

CONCLUSION

Our study shows that the degree of bradycardia has a significant impact on the course of SpO₂ only, but when associated with the additional presence of hypoxemia a significant impact on cerebral oxygenation parameters was seen (crStO₂, cFTOE). Furthermore, the additional presence of hypoxemia has a significant impact on FiO₂ delivered. Our study emphasizes the importance of HR and SpO₂ during neonatal resuscitation, underlining the relevance of hypoxemia during the early transitional phase.

Cardiac Output and Cerebral Oxygenation in Term Neonates during Neonatal Transition

The immediate transition from foetus to neonate includes substantial changes, especially concerning the cardiovascular system. Furthermore, the brain is one of the most vulnerable organs to hypoxia during this period. According to current guidelines for postnatal stabilization, the recommended parameters for monitoring are heart rate (HR) and arterial oxygen saturation (SpO₂). Recently, there is a growing interest in advanced monitoring of the cardio-circulatory system and the brain to get further objective information about the neonate’s condition during the immediate postnatal transition after birth. The aim of the present study was to combine cardiac output (CO) and brain oxygenation monitoring in term neonates after caesarean section in order to analyse the potential influence of CO on cerebral oxygenation during neonatal transition. This was a monocentric, prospective, observational study. For non-invasive cardiac output measurements, the electrical velocimetry (EV) method (Aesculon Monitor, Osypka Medical, CA, USA) was used. The pulse oximeter probe for SpO₂ and HR measurements was placed on the right hand or wrist. The cerebral tissue oxygen index (cTOI) was measured using a NIRO-200NX monitor with the near-infrared spectroscopy (NIRS) transducer on the right frontoparietal head. Monitoring started at minute 1 and was continued until minute 15 after birth. At minutes 5, 10, and 15 after birth, mean CO was calculated from six 10 s periods (with beat-to-beat analysis). During the study period, 99 term neonates were enrolled. Data from neonates with uncomplicated transitions were analysed. CO showed a tendency to decrease until minute 10. During the complete observational period, there was no significant correlation between CO and cTOI. The present study was the first to investigate a possible correlation between CO and cerebral oxygenation in term infants during the immediate neonatal transition. In term infants with uncomplicated neonatal transition after caesarean section, CO did not correlate with cerebral oxygenation.

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.

Sex related difference in cardiac output during neonatal transition in term neonates

Background

The immediate transition from foetus to neonate includes substantial changes especially concerning the cardiovascular system. As sex related differences have been shown in cardiovascular medicine, this topic warrants further investigation in neonatology. Aim: The aim of this present study was to measure cardiac output (CO) and cerebral oxygenation (cTOI) non-invasively in term neonates and to investigate potential sex related differences between female and male neonates after birth.

Methods

This is a mono-centric prospective observational study. For CO-measurements, the electrical velocimetry method was used. The pulse oximetry for arterial oxygen saturation and heart-rate measurements was placed on the right hand or wrist. cTOI was measured using a NIRO 200NX monitor. The near-infrared spectroscopy probe was positioned on the right side of forehead in each infant. Monitoring started at minute 1 and was continued until minute 15 after birth. At minutes 5, 10, and 15 after birth, CO was calculated as an average out of six 10-second periods.

Results

99 term neonates were enrolled. In our study population, we could identify 54 female and 45 male neonates. Males had higher cardiac output compared to females throughout the observational period, with a significant difference in minute 15 after birth (217, 95% CI: 203-231 mL/kg/min versus 178, 95% CI: 163-192 mL/kg/min; P<0.001). cTOI, SpO₂, and HR did not differ between male and female neonates.

Conclusions

The present work is the first to investigate sex related differences concerning cardiac output in term neonates during postnatal transition, showing a significantly higher cardiac output in male neonates 15 minutes after birth.

Non-invasive electrical cardiometry cardiac output monitoring during prehospital helicopter emergency medical care: a feasibility study

Purpose

Introducing advanced hemodynamic monitoring might be beneficial during Helicopter Emergency Medical Service (HEMS) care. However, it should not increase the on-scene-time, it should be easy to use and should be non-invasive. The goal of this study was to investigate the feasibility of non-invasive cardiac output measurements by electrical cardiometry (EC) and the quality of the EC signal during pre-hospital care provided by our HEMS.

Methods

A convenience sample of fifty patients who required HEMS assistance were included in this study. Problems with respect to connecting the patient, entering patient characteristics and measuring were inventoried. Quality of EC signal of the measurements was assessed during prehospital helicopter care. We recorded the number of measurements with a signal quality indicator (SQI) ≥ 80 and the number of patients having at least 1 measurement with a SQI ≥ 80. Furthermore, the SQI value distribution of the measurements within each patient was analysed.

Results

In the experience of the attending HEMS caregivers application of the device was easy and did not result in increased duration of on-scene time. Patch adhesion was reported as a concern due to clammy skin in 22% of all cases. 684 measurements were recorded during HEMS care. In 47 (94%) patients at least 1 measurement with an SQI ≥ 80 was registered. Of all recorded measurements 5.8% had an SQI < 40, 11.4% had an SQI 40–59, 14.9% had a SQI between 60 and 79 and 67.8% had SQI ≥ 80.

Conclusion

Cardiac output measurements are feasible during prehospital HEMS care with good quality of the EC signal. Monitoring was easy to use and quick to install. In our view it is an promising candidate for the prehospital setting. Further research is needed to determine its clinical value during clinical decision making.

Signal Quality of Electrical Cardiometry and Perfusion Index in Very Preterm Infants

OBJECTIVE

The use of noninvasive monitoring of neonatal hemodynamics is increasing in neonatal care. Methods include noninvasive cardiac output estimated by electrical cardiometry (EC) and peripheral perfusion as perfusion index (PI) using pulse oximetry. Our aim was to evaluate the feasibility to continuously monitor preterm infants with EC and PI during the first 2 postnatal days and the effects of averaging EC data in signal quality (SigQ) analysis.

DESIGN

Prospective observational study.

SETTING

Tertiary neonatal academic hospital.

PATIENTS

Preterm infants <32 weeks gestation from birth until 48 h.

MAIN OUTCOME MEASURES

Continuous EC and PI measurements. Feasibility was quantified as the time with high SigQ, classified using SigQ index in EC and exception codes in PI. Our predefined threshold for good feasibility was minimum of 24 h with high SigQ for both.

RESULTS

Twenty-two preterm infants (median [IQR] gestational age 28 + 6 (26 + 0, 30 + 4) weeks + days, birth weight 960 [773, 1,500] g) were included. We recorded a minimum of 24 h with high SigQ in 14 infants for EC (unaveraged data) and 22 infants for PI measurements. The median (range) % of recording time with high SigQ was 74% (50%, 88%) for EC and 94% (82%, 96%) for PI. Using 1 minute averaging for EC data resulted in an increase of infants with minimum 24 h of high SigQ to 21 infants.

CONCLUSIONS

EC and PI monitoring are feasible in preterm infants within the first 48 h, but SigQ remains problematic for EC. Signal dropout is masked in averaged EC values.

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.

NIRS in the fetal to neonatal transition and immediate postnatal period

Near-infrared spectroscopy (NIRS) offers the non-invasive continuous monitoring of cerebral oxygenation and perfusion. Cerebral regional oxygen (crSO2) measured via NIRS represents a mixed tissue saturation value, thus enabling information on the balance of cerebral oxygen delivery and oxygen consumption. Cerebral oxygenation is influenced by pulse oximeter saturation (SpO2), hemoglobin content, and cerebral blood flow. Furthermore, cerebral oxygenation is dependent on metabolic parameters, cardio circulatory parameters, perinatal- and postnatal interventions. Reference ranges for healthy term born and late preterm infants have already been published. It is feasible to increase crSO2 values above the 10th percentile by guiding medical support during neonatal to fetal transition. Guiding oxygen supply based on NIRS monitoring in addition to SpO2 monitoring showed that a reduction of the burden of cerebral hypoxia was possible. A currently ongoing study will give further information whether additional NIRS monitoring guiding medical support during neonatal to fetal transition is effective in improving neonatal outcome.

Effect of hemodialysis on impedance cardiography (electrical velocimetry) parameters in children

BACKGROUND

Pediatric hemodialysis (HD) patients have a high incidence of cardiovascular morbidity and mortality. The study aim was to investigate whether impedance cardiography (electrical velocimetry, EV) is suitable as a hemodynamic trend monitoring tool in pediatric patients during HD.

METHODS

Measurements by EV were obtained before, during, and after HD in a prospective single-center pediatric observational study. In total, 54 dialysis cycles in four different pediatric patients with end-stage kidney disease on chronic HD were included. EV parameters analyzed were heart rate (HR), stroke volume (SV), stroke volume index (SI), cardiac output (CO), cardiac index (CI), thoracic fluid content (TFC), index of contractility (ICON), stroke volume variation (SVV), variation of ICON (VIC), R-R interval (TRR), pre-ejection period (PEP), left ventricular ejection time (LVET), and systolic time ration (STR). Systemic vascular resistance index (SVRI) was calculated.

RESULTS

EV did measure significant changes in cardiovascular parameters associated with HD. The following parameters increased after HD: HR (9%), SVV (19%), VIC (33%), PEP (8%), and STR (18%). A decrease after HD was measured in SV (18%), SI (18%), CO (10%), CI (10%), TFC (10%), ICON (7%), TRR (7%), LVET (8%), and LVET (8%). SVRI was not affected by HD. The changes were correlated to ultrafiltration. HD cycles without fluid withdrawal also altered cardiovascular parameters.

CONCLUSIONS

Pediatric HD with and without fluid withdrawal changes hemodynamic EV monitoring parameters. Possibly EV may be useful to optimize HD management in pediatric patients.

Effect of Intrauterine Growth Restriction on Cerebral Regional Oxygen Saturation in Preterm and Term Neonates during Immediate Postnatal Transition

BACKGROUND

Intrauterine growth restriction (IUGR) is associated with adverse perinatal outcome. Affected fetuses commonly display typical blood flow redistribution towards the brain ("brain sparing"). Accordingly, increased cerebral oxygen saturation has been observed in IUGR neonates within the first days of life.

AIM

The aim of our study was to assess cerebral oxygenation behavior during immediate neonatal transition in IUGR infants.

METHODS

This is a retrospective single-center observational cohort study. Cerebral regional oxygen saturation (crSO2) was measured with near-infrared spectroscopy in neonates during the first 15 min after birth. Neonates with IUGR (IUGR group) were matched for gestational age (±1 week) and gender with neonates that were appropriate for gestational age (AGA). The AGA:IUGR matching ratio was 3:1. Arterial oxygen saturation (SpO2), heart rate (HR), crSO2, and cerebral fractional tissue oxygen extraction (cFTOE) were compared between the groups.

RESULTS

Between August 2010 and October 2017, 45 neonates with IUGR were identified and matched to 135 AGA neonates. Mean gestational age was 33.1 ± 3.0 weeks in the IUGR group and 33.5 ± 2.7 weeks in the AGA group. Mean birth weight was 1,559 ± 582 g in the IUGR group and 2,051 ± 679 g in the AGA group. There was a significant group difference in crSO2 beginning at 5 min and continuing for the rest of the observation time with higher crSO2 values in the IUGR group (main effect group: p = 0.011; interaction time × group: p = 0.039). In cFTOE, a significant difference could be observed at 5-9 and 11-13 min with lower rates of oxygen extraction in the IUGR group (main effect group: p = 0.025; interaction time × group: p = 0.463). Concerning SpO2 and HR, there was no significant difference between the IUGR and the AGA neonates.

CONCLUSION

Neonates of the IUGR group did show significantly higher crSO2 values and significantly lower cFTOE values already during immediate neonatal transition compared to the AGA group.

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.

Neonatal monitoring during delivery room emergencies

Fetal to neonatal transition after birth is a complex, well-coordinated process involving multiple organ systems. Any significant derangement in this process increases the risk of death and other adverse outcomes, underlying the importance of continuous monitoring to promptly detect and correct these derangements by effective resuscitative support. In recent years, there has been increasing efforts to move from subjective and discontinuous monitoring to more objective and continuous monitoring of different physiological parameters. Some of them like pulse oximetry for arterial oxygen saturation and electrocardiography for heart rate monitoring are now part of resuscitation guidelines whereas others like respiratory function monitoring, near infrared spectroscopy, or amplitude integrated electroencephalography are being evaluated. In this review, we describe some of the physiological parameters that can be monitored during delivery room emergencies and review the evidence for some of the monitoring technologies currently being evaluated.

Circulatory emergencies in the delivery room

The transition from fetal to neonatal life is a dramatic and complex process involving extensive physiologic changes, which are most obvious at the time of birth. Individuals who care for newly born infants must monitor the progress of the transition and be prepared to intervene when necessary. In the majority of births, this transition occurs without a requirement for any significant assistance. If newborns require assistance, the majority of the time respiratory support is all that is required. In some instances, however, there are circulatory emergencies that need to be rapidly identified or there may be dire consequences including death in the delivery room. This chapter will review various pathologies that are circulatory emergencies, and discuss how to assess them. We will also review new technologies which may help providers better understand the circulatory status or hemodynamic changes in the delivery room including heart rate, cardiac output, cerebral oxygenation and echocardiography.

Lactate acidosis and cardiac output during initial therapeutic cooling in asphyxiated newborn infants

Aim

We hypothesized that compromised cardiac output in asphyxiated infants may influence on the rate of disappearance of lactate due to insufficient perfusion.

Methods

The study was a prospective, observational study, where infants with perinatal asphyxia who met the criteria for therapeutic hypothermia were included. Cardiac output, stroke volume and heart rate were measured by electrical velocimetry in 15 newborn infants with perinatal asphyxia during the first six hours of active therapeutic hypothermia. Results from routine blood samples were collected retrospectively. Cardiac parameters were also measured in 10 healthy, term infants after caesarian section. Cardiac parameters were compared between the asphyxiated group and the control group prior to and during hypothermia. Rate of disappearance of lactate was correlated to cardiac output in the asphyxiated infants.

Results

Cardiac output was stable in the healthy infants from 0.5 to 6 hours postnatally. The infants with perinatal asphyxia had lower cardiac output prior to and during therapeutic hypothermia compared to the control group. Rate of disappearance of lactate was not related to cardiac output.

Conclusion

An association between disappearance of lactate acidosis and low cardiac output was not confirmed. A low rate of disappearance of lactate may rather be an indicator of organ injury due to asphyxia.

Heart Rate Monitoring in Newborn Babies: A Systematic Review

BACKGROUND

Around 10% of newborn infants require assistance during transition after birth. Heart rate (HR) is the most important clinical indicator to evaluate the clinical status of a newborn.

AIM

Our study aimed to review all established and novel methods to detect HR in babies giving special consideration to non-invasive techniques.

METHODS

We performed a systematic literature search on the following databases: MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and CINAHL. The inclusion criteria were studies on methods to detect HR in both term and preterm infants in comparison to one of the current gold standards: pulse oximetry (PO) or electrocardiography (ECG) published in the last 15 years. Two independent reviewers screened titles and abstracts for eligibility. Data extracted in an Excel table were analysed to produce a narrative review structured around the type of monitoring, identified obstacles in use, as well as methods to overcome these limitations.

RESULTS

The search revealed 649 studies after duplicates were removed. Full article analysis was performed on 26 studies of which 25 met the inclusion criteria. Well established methods such as auscultation and palpation, although rapid and easily available, have been shown to be inaccurate. ECG and PO were both more precise but the delay in obtaining a reliable HR signal from birth often exceeded 1-2 min. Novel sensors offered the advantages of minimally obtrusive technologies but have limitations mainly due to movement artefact, bad sensor coupling, intermittent measurement, and poor-quality recordings.

CONCLUSIONS

The limitations of existing methods have a potential impact on short- and long-term morbidity and mortality outcomes. The development of a technological solution to determine HR accurately and quickly in babies at birth has immense implications for further research and can guide interventions, such as placental transfusion and resuscitation.

Oxygen Saturation Targeting During Delivery Room Stabilization: What Does This Mean for Regional Cerebral Oxygenation?

Objective: To investigate if preterm neonates with arterial oxygen saturation (SpO₂)<80% at 5 min after birth show different regional cerebral tissue oxygen saturation (rcStO₂), compared to infants reaching the target. Methods: Retrospective analysis of four prospective observational studies. Preterm neonates needing respiratory support during delivery room stabilization were included. Regional cerebral tissue oxygen saturation was measured with near-infrared spectroscopy (NIRS) during the first 15 min after birth along with SpO₂ and heart rate (HR). Neonates were divided into two groups: those with a 5-min SpO₂ ≥ 80% ("≥80% group") and those with a 5-min SpO₂ < 80% ("<80% group"). Groups were compared regarding rcStO₂, SpO₂, and HR. Furthermore, we analyzed whether a 5-min SpO₂ < 80% was associated with a rcStO₂ below the 10th percentile at the same time point. Results: 146 neonates were included, with 68 (47%) in the "≥80% group" and 78 (53%) in the "<80% group." Neonates in the " <80% group" had a significantly lower rcStO₂ (p < 0.001). Furthermore, 80.3% of neonates in the " <80% group" and 23.4% in the "≥80% group" had rcStO₂ values below the 10th percentile at 5 min (p < 0.001). HR was significantly lower at minute 3 and 4 in the " <80% group" (p < 0.002). Conclusion: Preterm infants needing respiratory support, who do not reach the SpO₂ target of 80% at 5 min after birth, show significantly diminished rcStO₂ values compared to neonates reaching the target.

Tactile stimulation during neonatal transition and its effect on vital parameters in neonates during neonatal transition

AIM

This study analysed tactile stimulation during neonatal transition and resuscitation in preterm and term neonates born by Caesarean delivery. It examined the frequency, location and body region, duration and possible effects of stimulation on heart rate and arterial oxygen saturation (SpO₂ ).

METHODS

Two independent investigators analysed video recordings of tactile stimulation on term and preterm neonates during neonatal transition from January 2012 to December 2014. They were recorded during a prospective observational study and randomised controlled trial at a tertiary centre, the Medical University of Graz, Austria. SpO₂ and heart rate were continuously recorded. Data on the frequency, body region and duration of stimulation were collected. To investigate the possible effects of stimulation, SpO₂ and heart rate were compared before and after stimulation.

RESULTS

Term infants received tactile stimulation more than once, and it tended to start later, last longer and be applied in more locations than in preterm infants. Only preterm infants showed a significant increase in SpO₂ after stimulation and heart rates did not show any significant changes in either group.

CONCLUSION

Tactile stimulation was applied in different ways to preterm and term infants during neonatal transition and SpO₂ showed a significant increase in preterm infants.

Cerebral Blood Volume During Neonatal Transition in Term and Preterm Infants With and Without Respiratory Support

Background: Recently, we demonstrated that in healthy newborn infants cerebral blood volume (CBV) was decreasing continuously after birth. We hypothesized that this was due to the increase in oxygen delivery to the brain during neonatal transition. Thus delayed cerebral oxygen delivery in infants in need for respiratory support (RS) during postnatal stabilization might influence changes in CBV. Objective: Aim of the study was to evaluate transitional changes in CBV immediately after birth in term and preterm infants with and without need of RS. Methods: We performed a post-hoc analysis of data collected as primary and secondary outcome parameters in prospective observational studies and randomized controlled trials at the Medical University of Graz (Austria). NIRS measurements by using "NIRO 200-NX" (Hamamatsu, Japan) were carried out over the first 15 min after birth in term and preterm infants delivered by cesarean section with and without requirement for RS. Results: In 204 neonates, we observed a significant decrease in CBV within the first 15 min after birth (p < 0.001) with a trend toward smaller ΔCBV in neonates receiving RS (p = 0.097) compared to neonates without RS. Differences of ΔCBV between groups reached statistically significance (p < 0.05) at minutes 2, 6, and 7, and showed a trend (p < 0.1) at minutes 3, 4, and 5. After adjusting for gestational age, these differences became smaller and failed to reach significance. Conclusions: We observed a significant decrease of CBV in term and preterm infants with and without RS. Interestingly, ΔCBV was smaller in the first 7 min in neonates with RS reaching statistically significance (p < 0.05) at minutes 2, 6, and 7. This study cannot differentiate, whether RS itself or the condition leading to requirement for RS is responsible for the observed CBV behavior.

Objective cardiovascular assessment in the neonatal intensive care unit

Traditionally, cardiovascular well-being was essentially based on whether the mean blood pressure was above or below a certain value. However, this singular crude method of assessment provides limited insight into overall cardiovascular well-being. Echocardiography has become increasingly used and incorporated into clinical care. New objective modality assessments of cardiovascular status continue to evolve and are being evaluated and incorporated into clinical care. In this review article, we will discuss some of the recent advances in objective assessment of cardiovascular well-being, including the concept of multimodal monitoring. Sophisticated haemodynamic monitoring systems are being developed, including mechanisms of data acquisition and analysis. Their incorporation into clinical care represents an exciting next stage in the management of the infant with cardiovascular compromise.

How to assess hemodynamic status in very preterm newborns in the first week of life?

BACKGROUND

Assessing hemodynamic status in preterm newborns is an essential task, as many studies have shown increased morbidity when hemodynamic parameters are abnormal. Although oscillometric monitoring of arterial blood pressure (BP) is widely used due to its simplicity and lack of side effects, these values are not always correlated with microcirculation and oxygen delivery.

OBJECTIVES

This review focuses on different tools for the assessment of hemodynamic status in preterm newborns. These include the measurement of clinical (BP, capillary refill time and urinary output (UO)) or biological parameters (lactate analysis), functional echocardiography, and near-infrared spectroscopy (NIRS). We describe the concepts and techniques involved in these tools in detail, and examine the interest and limitations of each type of assessment.

CONCLUSIONS

This review highlights the complementarities between the different parameters used to assess hemodynamic status in preterm newborns during the first week of life. The analysis of arterial BP measured by oscillometric monitoring must take into account other clinical data, in particular capillary refill time and UO, and biological data such as lactate levels. Echocardiography improves noninvasive hemodynamic management in newborns but requires specific training. In contrast, NIRS may be useful in monitoring the clinical course of infants at risk of, or presenting with, hypotension. It holds the potential for early and noninvasive identification of silent hypoperfusion in critically ill preterm infants. However, more data are needed to confirm the usefulness of this promising tool in significantly changing the outcome of these infants.