The Relationship between blood pressure parameters and left ventricular output in neonates

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.

Blood pressure trends following birth in infants born under 25 weeks' gestational age: a retrospective cohort study

OBJECTIVE

The aim of our study was to describe postnatal blood pressure (BP) trends and evaluate relevant dynamics and outcomes for a subgroup of extremely preterm (EPT) infants.

DESIGN

Retrospective observational cohort study.

SETTING

Patients admitted to Karolinska University Hospital Stockholm.

PATIENTS

EPT infants born between 22+0 and 24+6 weeks' gestational age (GA) undergoing invasive, continuous BP monitoring through an umbilical arterial catheter.

MAIN OUTCOME MEASURES

Physiological BP trends, the influence of cardiovascular active interventions and fluid boluses on BP, and relevant adverse outcomes, including intraventricular haemorrhage (IVH), necrotising enterocolitis (NEC) and death, were mapped over the first week of life.

RESULTS

We included 125 infants between January 2009 and November 2021. Mean BP values were 31 mm Hg, 32 mm Hg and 35 mm Hg, at 3 hours, 24 hours and 48 hours, respectively. A pronounced BP dip and nadir were observed around 20 hours, with a mean BP value of 32 mm Hg. 84% received fluid boluses within the first week of life; however, we could not observe any noteworthy change in BP following administration. Only 8% of patients received cardiovascular active drugs, which were too few to infer drug-specific effects. Overall, 48% developed IVH, 15% developed NEC and 25% died.

CONCLUSIONS

Approximating clinically acceptable mean BP values using GA gives underestimations in these infants. The postnatal BP dip should be regarded as a physiological phenomenon and not automatic grounds for interventions which may momentarily stabilise BP but have no appreciable short-term or long-term effects. Further studies are warranted for improved understanding of clinically relevant trends and outcomes.

Arterial pressure is not reflective of right ventricular function in neonates with hypoxic ischemic encephalopathy treated with therapeutic hypothermia

AIM

to evaluate the correlation of recovery of arterial pressure with physiological recovery among patients with hypoxic ischemic encephalopathy undergoing therapeutic hypothermia.

METHODS

At 24 h postnatal age, we compared 53 neonates of whom 22 (41%) were inotrope-treated to those untreated with cardiovascular medications.

RESULTS

Inotrope-treated patients had persistent severe right ventricular (RV) dysfunction and evidence of abnormal brain tissue oxygen delivery, despite recovered arterial pressure.

CONCLUSION

Arterial pressure is not reflective of RV function and the need for inotropic agents may be reflective of abnormal brain tissue oxygen delivery.

Targeted Neonatal Echocardiography in Patients With Hemodynamic Instability

Targeted neonatal echocardiography (TNE) has been increasingly used at the bedside in neonatal care to provide an enhanced understanding of physiology, affecting management in hemodynamically unstable patients. Traditional methods of bedside assessment, including blood pressure, heart rate monitoring, and capillary refill are unable to provide a complete picture of tissue perfusion and oxygenation. TNE allows for precision medicine, providing a tool for identifying pathophysiology and to continually reassess rapid changes in hemodynamics. A relationship with cardiology is integral both in training as well as quality assurance. It is imperative that congenital heart disease is ruled out when utilizing TNE for hemodynamic management, as pathophysiology varies substantially in the assessment and management of patients with congenital heart disease. Utilizing TNE for longitudinal hemodynamic assessment requires extensive training. As the field continues to grow, guidelines and protocols for training and indications are essential for ensuring optimal use and providing a platform for quality assurance.

How to diagnose and treat acute pulmonary hypertension when you have no cardiology support

Acute pulmonary hypertension (aPH) is a complex, physiology-driven disorder that causes critical illness in newborns, the hallmark of which is elevated pressure in the pulmonary vascular bed. Several underlying hemodynamic phenotypes exist, including classic arterial aPH with resistance-driven elevations in pulmonary arterial pressure (PAP), alongside flow-driven aPH from left-to-right shunt lesions, and primary left ventricular dysfunction with pulmonary venous hypertension and elevated left atrial pressure. Targeted neonatal echocardiography (TnECHO) is an important tool for evaluation of hemodynamics in aPH and is highly useful for evaluating modulators of disease and targeting cardiovascular therapy. The diagnostic approach to aPH includes confirmation of elevation of PAP, evaluation of the cause and exclusion of structural cardiac disease, assessment of the response of the myocardium to adverse loading conditions, and appraisal of the adequacy of systemic blood flow. Therapeutic goals include support of right ventricular (RV) function, RV afterload reduction, and selection of cardiotropic agents that support underlying pathophysiology without adverse effects on heart rate or pulmonary vascular resistance in addition to routine supportive intensive care. Training programs for TnECHO exist across multiple jurisdictions and strong correlation with pediatric cardiology assessment has been demonstrated. Future directions include adapting TnECHO training with a greater focus on achieving competency, and further research into the role of the modality in providing individualized cardiovascular care for patients with heterogenous underlying physiology, and its effect on key neonatal outcomes.

Fluid-Structure Interaction Model for Predicting Surgical Result of Total Anomalous Pulmonary Venous Connection and Estimating Pulmonary Venous Properties

OBJECTIVES

To build a fluid-structure interaction model of pulmonary veins with total anomalous pulmonary venous connection, which can be used to predict the result of surgical treatment and at the same time to estimate the elastic properties of pulmonary veins based on patient-specific data and clinic postoperative results.

METHODS

The fluid-structure interaction (FSI) model was used to simulate the anastomosis on pulmonary veins based on computed tomography angiography data collected from three children with total anomalous pulmonary venous connection (TAPVC), supra-cardiac type. The deformation and the stress of anastomosis, and also the velocity of blood flow were calculated in fluid-structure coupling algorithm. During the simulation the variable boundary conditions were applied, including the thickness of vessel wall and the vessel elasticity for which was selected a range of values. The calculation results were finally compared to postoperative results of same patients and discussed. The corresponding outcomes are given in the conclusions section.

RESULTS

The blood flow velocity through the outlet will vary depending on the properties of vessels, including physical properties and thickness of vessel wall. The stress on vessel is lower for smaller values of Young's modulus. The calculated blood flow velocity correlates well with the postoperative results for the Young's modulus of vessels ranging from 0.5 to 1.0 MPa.

CONCLUSIONS

The FSI model has high potential to predict the result of surgery for TAPVC and to estimate the physical properties of pulmonary vein. This model also has potential to guide the strategy for surgical treatment.

Quality Improvement Initiative in the NICU for Improved Practice of Cuff Blood Pressure Measurements

BACKGROUND

Extreme preterm infants face lengthy hospitalizations and are often subjected to painful stimuli. These stimuli may be related to routine caregiving that may negatively impact long-term developmental outcomes. Frequently obtained cuff blood pressure (BP) measurements are an example of a potentially noxious stimulus to preterm infants that may have a cumulating impact on development.

PURPOSE

The primary aim was to explore the frequency of cuff BP measurements obtained in hemodynamically stable extreme preterm infants in the neonatal intensive care unit (NICU). Our secondary aim was to reduce the number of cuff BP measurements obtained in hemodynamically stable extreme preterm infants in the NICU.

METHODS

Quality improvement methodologies per the Institute for Healthcare Improvement were used combined with a multidisciplinary approach. Participants were infants born less than 27 weeks of gestation and discharged home. The baseline period was 2015 through Q2-2018 and the intervention period was Q3-2018 through Q1-2020. The electronic medical record was used to collect data and Minitab Statistical Software was used for data analysis.

FINDINGS/RESULTS

A baseline of 5.0% of eligible patients received the desired number of cuff BP measurements and increased to 63.2% after the intervention period.

IMPLICATIONS FOR PRACTICE

Findings demonstrate that using quality improvement methodology can improve clinical care. Findings suggest the feasibility and safety of reducing the number of cuff BP measurements obtained on hemodynamically stable infants in the NICU.

IMPLICATIONS FOR RESEARCH

Future endeavors should aim to reduce the quantity of painful stimuli in the NICU. Long-term developmental outcomes should be correlated in these patients.

Blood pressure, organ dysfunction, and mortality in preterm neonates with late-onset sepsis

BACKGROUND

The objective of this study was to investigate the association between systolic, diastolic, and mean blood pressures (SBP, DBP, and MBP) and adverse outcomes in preterm neonates with late-onset sepsis (LOS).

METHODS

This is a two-center retrospective study over 6 years. Neonates <35 weeks gestational age (GA) with blood ± cerebrospinal fluid culture positive for organisms other than coagulase-negative Staphylococcus at >72 h age were included. Outcome measures were organ dysfunction (ODF) using the predefined criteria and post-ODF mortality (≤7 days from LOS onset). The lowest noninvasive blood pressures (BPs) recorded at baseline (24-48 h pre-LOS) and 0-12, 13-24, 25-36, and 37-48 h post LOS were analyzed.

RESULTS

Of 147 neonates, ODF occurred in 70 (48%), of which 20 (29%) died. ODF was associated with a drop in all BP components, starting 0-12 h post-LOS onset (p < 0.01 for all); BPs remained unchanged in the non-ODF group. Mortality was associated with a greater reduction in SBP [-13 (-19, -8) vs. -4 (-8, 0); p < 0.01] and MBP [-9 (-13, -5) vs. +1 (-1, +4); p = 0.03] 0-12 h post-LOS onset. SBP had a higher area under the curve for mortality than MBP and DBP (0.83, 0.81, and 0.78, respectively). An inverse relation may exist between corrected GA and percentage reduction in SBP from baseline for equivalent risk of death.

CONCLUSIONS

Reduction in BPs early in illness may identify preterm neonates at the highest risk of ODF and mortality from LOS.

IMPACT

Drop in BPs from baseline starting in the immediate post-illness onset period may identify preterm neonates at the highest risk of developing ODF and mortality in LOS. Lowest systolic followed by mean BP measured during the first 12 h of illness provided the highest discriminating ability for LOS-related mortality. Absolute BPs recorded during the first 12 h of illness performed better than relative change from baseline for identifying neonates at risk of LOS-related mortality. The specific BP thresholds identified in this study may inform future therapeutic trials.

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.

Baseline Values of Left Ventricular Systolic Function in Preterm Infants With Septic Shock: A Prospective Observational Study

BACKGROUND AND AIM

Guidelines recommended that cardiac index (CI) of term infants with septic shock should reach the target level of 3.3-6.0L/(min⋅m²). However, there are still no standard values for preterm infants with septic shock. Herein, we investigated the functional echocardiographic baseline values of left ventricular (LV) systolic functional parameters at the onset of septic shock in preterm infants and possible correlations between baseline values and poor outcomes.

MATERIALS AND METHODS

This was a prospective, observational, and longitudinal single-center study. Eligible infants were monitored for LV systolic functional parameters using functional echocardiography at the onset of septic shock. The primary study outcome was the difference in the baseline value of LV systolic functional parameters in preterm infants with septic shock with different gestational age (GA) and birth weight (BW). The secondary outcome was septic shock-associated death or severe brain injury (including grade 3-4 intraventricular hemorrhage or periventricular leukomalacia).

RESULTS

In total, 43 subjects met the criteria, with a median GA of 32^1/7 weeks and BW of 1800 grams. No difference was observed in baseline values of LV systolic functional parameters among infants with different GA and BW. Infants were assigned to good and poor outcomes groups based on septic shock-associated death or severe brain injury. Out of 43 infants, 29 (67.4%) had good outcomes vs. 14 (32.6%) with poor outcomes. Stroke index (SI) [18.2 (11.1, 18.9) mL/m² vs. 23.5 (18.9, 25.8) mL/m², p = 0.017] and cardiac index (CI)[2.7 (1.6, 3.5) L/(min⋅m²) vs. 3.4 (3.0, 4.8) L/(min⋅m²), p = 0.015] in infants with poor outcomes were significantly lower (P < 0.05). Receiver operating characteristic (ROC) curve analysis showed that the cut-off values of SI and CI for predicting poor outcomes in preterm infants with septic shock were 19.5 mL/m² (sensitivity, 73.9%; specificity, 81.8%) and 2.9L/(min⋅m²) (sensitivity, 78.3%; specificity, 72.7%), with area under the ROC curve (AUC) value of 0.755 and 0.759, respectively.

CONCLUSION

There were no differences in baseline LV systolic functional values among preterm infants with septic shock with different GA and BW. However, preterm infants with SI<19.5mL/m² and/or CI<2.9L/(min⋅m²) at the onset of septic shock were at high risk of having poor outcomes.

Hemodynamic dysfunction in neonatal sepsis

Cardiovascular disturbances are a frequent occurrence in neonatal sepsis. Preterm and term infants are particularly vulnerable due to the unique features of their cardiovascular function and reserve, compared to older children and adults. The clinical manifestations of neonatal sepsis are a product of the variable inflammatory pathways involved (warm vs. cold shock physiology), developmental state of the cardiovascular system, and hormonal responses. Targeted neonatal echocardiography has played an important role in advancing our knowledge, may help delineate specific hemodynamic phenotypes in real-time, and supports an individualized physiology-based management of sepsis-associated cardiovascular dysfunction. IMPACT: Cardiovascular dysfunction is a common sequela of sepsis. This review aims to highlight the pathophysiological mechanisms involved in hemodynamic disturbance in neonatal sepsis, provide insights from targeted neonatal echocardiography-based clinical studies, and suggest its potential incorporation in day-to-day management.

Management of systemic hypotension in term infants with persistent pulmonary hypertension of the newborn: an illustrated review

In persistent pulmonary hypertension of the newborn (PPHN), the ratio of pulmonary vascular resistance to systemic vascular resistance is increased. Extrapulmonary shunts (patent ductus arteriosus and patent foramen value) allow for right-to-left shunting and hypoxaemia. Systemic hypotension can occur in newborns with PPHN due to variety of reasons, such as enhanced peripheral vasodilation, impaired left ventricular function and decreased preload. Systemic hypotension can lead to end organ injury from poor perfusion and hypoxaemia in the newborn with PPHN. Thus, it must be managed swiftly. However, not all newborns with PPHN and systemic hypotension can be managed the same way. Individualised approach based on physiology and echocardiographic findings are necessary to improve perfusion to essential organs. Here we present a review of the physiology and mechanisms of systemic hypotension in PPHN, which can then guide treatment.

What Inotrope and Why?

Primary function of cardiovascular system is to meet body's metabolic demands. The aim of inotrope therapy is to minimise adverse impact of cardiovascular compromise. Current use of inotropes is primarily guided by the pathophysiology of cardiovascular compromise and anticipated actions of inotropes. Lack of significant reduction in morbidity and mortality associated with cardiovascular compromise despite inotrope use, highlights major gaps in our understanding of circulatory targets, thresholds and choices of inotrope therapy. Thus far, prevention of cardiovascular compromise remains the most effective strategy to optimize outcomes. Studies of alternative design are needed for further advancement in cardiovascular therapy in neonates.

Point-of-care ultrasound in the neonatal ICU

PURPOSE OF REVIEW

Point-of-care ultrasound (POCUS) is an emerging clinical tool in the neonatal intensive care unit (NICU). Recent literature describing the use of POCUS for various applications in the NICU has garnered increased interest among neonatologists.

RECENT FINDINGS

Diagnostic applications for POCUS in the NICU include the evaluation and serial monitoring of common pulmonary diseases, hemodynamic instability, patent ductus arteriosus (PDA), persistent pulmonary hypertension of the newborn (PPHN), necrotizing enterocolitis (NEC), and intraventricular hemorrhage (IVH), among others. Procedural applications include vascular access, endotracheal intubation, lumbar puncture, and fluid drainage.

SUMMARY

Experience with POCUS in the NICU is growing. Current evidence supports the use of POCUS for a number of diagnostic and procedural applications. As use of this tool increases, there is an urgent need to develop formal training requirements specific to neonatology, as well as evidence-based guidelines to standardize use across centers.

Impaired Right Ventricular Performance Is Associated with Adverse Outcome after Hypoxic Ischemic Encephalopathy

Rationale: Asphyxiated neonates with hypoxic ischemic encephalopathy (HIE) are at risk of myocardial dysfunction; however, echocardiography studies are limited and little is known about the relationship between hemodynamics and brain injury.Objectives: To analyze the association between severity of myocardial dysfunction and adverse outcome as defined by the composite of death and/or abnormal magnetic resonance imaging.Methods: Neonates with HIE undergoing therapeutic hypothermia were enrolled. Participants underwent echocardiography at 24 hours, 72 hours (before rewarming), and 96 hours (after rewarming). Cerebral hemodynamics were monitored by near-infrared spectroscopy and middle cerebral artery Doppler.Measurements and Main Results: Fifty-three patients with a mean gestation and birthweight of 38.8 ± 2.0 weeks and 3.33 ± 0.6 kg, respectively, were recruited. Thirteen patients (25%) had mild encephalopathy, 27 (50%) had moderate encephalopathy, and 13 (25%) had severe encephalopathy. Eighteen patients (34%) had an adverse outcome. Severity of cardiovascular illness (P < 0.001) and severity of neurologic insult (P = 0.02) were higher in neonates with adverse outcome. Right ventricle (RV) systolic performance at 24 hours was substantially lower than published normative data in all groups. At 24 hours, lower tricuspid annular plane systolic excursion (P = 0.004) and RV fractional area change (P < 0.001), but not pulmonary hypertension, were independently associated with adverse outcome on logistic regression. High brain regional oxygen saturation (P = 0.007) and low middle cerebral artery resistive index (P = 0.04) were associated with RV dysfunction on post hoc analysis.Conclusions: RV dysfunction is associated with the risk of adverse outcome in asphyxiated patients with HIE undergoing hypothermia. Echocardiography may be a valuable diagnostic and prognostic tool in this vulnerable population.

Continuous vital sign analysis for predicting and preventing neonatal diseases in the twenty-first century: big data to the forefront

In the neonatal intensive care unit (NICU), heart rate, respiratory rate, and oxygen saturation are vital signs (VS) that are continuously monitored in infants, while blood pressure is often monitored continuously immediately after birth, or during critical illness. Although changes in VS can reflect infant physiology or circadian rhythms, persistent deviations in absolute values or complex changes in variability can indicate acute or chronic pathology. Recent studies demonstrate that analysis of continuous VS trends can predict sepsis, necrotizing enterocolitis, brain injury, bronchopulmonary dysplasia, cardiorespiratory decompensation, and mortality. Subtle changes in continuous VS patterns may not be discerned even by experienced clinicians reviewing spot VS data or VS trends captured in the monitor. In contrast, objective analysis of continuous VS data can improve neonatal outcomes by allowing heightened vigilance or preemptive interventions. In this review, we provide an overview of the studies that have used continuous analysis of single or multiple VS, their interactions, and combined VS and clinical analytic tools, to predict or detect neonatal pathophysiology. We make the case that big-data analytics are promising, and with continued improvements, can become a powerful tool to mitigate neonatal diseases in the twenty-first century.