Evaluation and treatment of hypotension in the preterm infant

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.

Identification of the Best Predictive Model for Mortality in Outborn Neonates-Retrospective Cohort Study

BACKGROUND

Transportation of sick newborns is a major predictor of outcome. Prompt identification of the sickest newborns allows adequate intervention and outcome optimization. An optimal scoring system has not yet been identified.

AIM

To identify a rapid, accurate, and easy-to-perform score predictive for neonatal mortality in outborn neonates.

MATERIAL AND METHODS

All neonates admitted by transfer in a level III regional neonatal unit between 1 January 2015 and 31 December 2021 were included. Infants with congenital critical abnormalities were excluded (N = 15). Gestational age (GA), birth weight (BW), Apgar score, place of birth, time between delivery and admission (AT), early onset sepsis, and sick neonatal score (SNS) were collected from medical records and tested for their association with mortality, including in subgroups (preterm vs. term infants); GA, BW, and AT were used to develop MSNS-AT score, to improve mortality prediction. The main outcome was all-cause mortality prediction. Univariable and multivariable analysis, including Cox regression, were performed, and odds ratio and hazard ratios were calculated were appropriate.

RESULTS

418 infants were included; 217/403 infants were born prematurely (53.8%), and 20 died (4.96%). Compared with the survivors, the non-survivors had lower GA, BW, and SNS scores (p < 0.05); only the SNS scores remained lower in the subgroup analysis. Time to admission was associated with an increased mortality rate in the whole group and preterm infants (p < 0.05). In multiple Cox regression models, a cut-off value of MSNS-AT score ≤ 10 was more precise in predicting mortality as compared with SNS (AUC 0.735 vs. 0.775) in the entire group and in the preterm infants group (AUC 0.885 vs. 0.810).

CONCLUSIONS

The new MSNS-AT score significantly improved mortality prediction at admission in the whole study group and in preterm infants as compared with the SNS score, suggesting that, besides GA and BW, AT may be decisive for the outcome of outborn preterm infants.

Noradrenaline use for neonatal circulatory support

AIM

Noradrenaline (NA) has been used in preterm and term infants for circulatory support due to conditions including sepsis and pulmonary hypertension of the newborn. Treatment in neonates varies widely between institutions and respective neonatologists. The aim of this study is to determine the indications, use and effects of NA in preterm and term infants requiring circulatory support at the Royal Brisbane and Women's Hospital neonatal intensive care unit. We also aim to determine whether there were any differences between neonates who survived versus those who died after NA treatment.

METHODS

Data were collected from Royal Brisbane and Women's Hospital neonatal unit database including preterm and term infants between 1 January 2016 and 31 May 2021. Analysis included indication for use, blood pressure response, perfusion parameters, haemodynamic indicators and adverse effects.

RESULTS

NA treatment was documented in 37 patients requiring treatment of cardiovascular compromise. In 11 (30%) of these infants the indication for use was due to sepsis, 19 (51%) infants had pulmonary hypertension of the newborn, and 7 (19%) infants were diagnosed with hypotension prior to NA administration. Infants who subsequently died (49%) represented a younger gestational age population and exhibited worse cardiac compromise prior to NA administration. Tachycardia occurred in 15 (31%) infants and 1 (2.7%) infant developed transient hypertension. Overall improvement in poor tissue perfusion was seen after NA use.

CONCLUSION

NA use in treating neonates requiring circulatory support appears to be effective. Further prospective trials into NA use as a first- or second-line inotropic agent would be valuable.

Maximum vasoactive-inotropic score and mortality in extremely premature, extremely low birth weight infants

OBJECTIVE

To determine the relationship between maximum vasoactive-inotropic (VIS^max) and mortality in extremely premature (<29 weeks completed gestation), extremely low birth weight (ELBW, <1000 g) infants.

STUDY DESIGN

Single center, retrospective, and observational cohort study.

RESULTS

We identified 436 ELBW, <29 week, inborn infants cared for during the study period. Compared to infants with VIS^max of 0, the frequency of mortality based on VIS^max ranged from 3.3-fold to 46.1-fold. VIS^max > 30 was associated with universal mortality. Multivariable modeling that included gestational age, birth weight, and VIS^max revealed significant utility to predict mortality with negative predictive value of 87.0% and positive predictive value of 84.8% [adjusted AUROC: 0.90, (0.86-0.94)] among patients that received vasoactive-inotropic treatment.

CONCLUSION

VIS^max is an objective measure of hemodynamic/cardiovascular support that was directly associated with mortality in extremely premature ELBW infants. The VIS^max represents an important step towards neonatal precision medicine and risk stratification of extremely premature ELBW infants.

Association of inotrope use with neurodevelopmental outcomes in infants <29 weeks gestation: a retrospective cohort study

OBJECTIVE

The primary objective was to compare neurodevelopmental (ND) outcomes at 18-24 months in preterm infants <29 weeks gestational age (GA) who received versus those who did not receive inotropes in the first week of life. The secondary objective was to assess ND outcomes according to the duration of inotropic support in the first week of life (≤3 or >3 days).

STUDY DESIGN

Retrospective population-based cohort study of preterm infants <29 weeks GA admitted to participating neonatal intensive care units (NICUs) of the Canadian Neonatal Network (CNN) from January 2010 to September 2011 with follow-up data available at 18-24 months. Neurodevelopmental outcomes were assessed using the Bayley Scales of Infant and Toddler Development-Third Edition (BSID-III). Long-term outcomes were categorized as neurodevelopmental impairment (NDI) and significant neurodevelopmental impairment (sNDI), and effect modification due to other neonatal morbidities including receipt of antenatal steroids, GA, small for gestational age (SGA) status, sex, score for neonatal acute physiology (SNAP-II) >20, postnatal steroids, bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH) grade ≥3/periventricular leukomalacia (PVL), early- and late-onset sepsis, retinopathy of prematurity (ROP) and necrotizing enterocolitis (NEC) was assessed. Maternal and infant demographic characteristics and short- and long-term outcomes were compared using Pearson's Chi-square test for categorical variables and Student's t-test or the Wilcoxon rank test for continuous variables. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated using multivariable regression analysis.

RESULTS

Of the 491 (18.7%) eligible preterm infants who received inotropes during the first week of life, 314 (64%) survived to NICU discharge and 245 (78%) had ND outcome data available. A total of 1775 eligible preterm infants did not receive inotropes in the first week of life; 1647 (92.7%) survived to NICU discharge and 1149 (70%) had ND outcome data. Maternal and infant characteristics associated with infants receiving inotropes included: younger maternal age, clinical chorioamnionitis, no antenatal steroids, outborn, lower GA, BW and Apgar scores at both one and five minutes; and higher SNAP-II scores (p < .05). Infants who received inotropes in the first week of life were more likely to be require postnatal steroids, had higher rates of BPD, IVH grade ≥3/PVL, early- and late-onset sepsis, ROP, NEC and mortality (p < .05). Infants who received inotropes in the first week of life also had higher rates of sensorineural or mixed hearing loss with an AOR (95% CI) of 1.99 (1.13, 3.49). After adjusting for confounding variables, there was no difference in the risk of NDI or sNDI between infants who did and did not receive inotropes in the first week of life. Of the infants with neurodevelopmental outcome data available, 186 received inotropes for ≤3 days and 59 for >3 days. After adjusting for confounding variables there was no difference in the risk of NDI or sNDI. Infants who received inotropes for >3 days were more likely to have lower BSID-III cognitive [AOR 2.43 95% CI (1.03, 5.76)] and motor scores <85 [AOR 2.38 95% CI (1.07, 5.30)] respectively.

CONCLUSIONS

In this large, population-based cohort, infants who received inotropes in the first week of life were at increased risk for sensorineural or mixed hearing loss. There was no difference in NDI or sNDI after adjusting for confounding variables. A longer duration of inotrope use in the first week of life was associated with lower BSID-III cognitive and motor scores, but no difference in overall NDI or sNDI.

Propofol in neonates causes a dose-dependent profound and protracted decrease in blood pressure

AIM

To analyse the effects of different propofol starting doses as premedication for endotracheal intubation on blood pressure in neonates.

METHODS

Neonates who received propofol starting doses of 1.0 mg/kg (n = 30), 1.5 mg/kg (n = 23) or 2.0 mg/kg (n = 26) as part of a previously published dose-finding study were included in this analysis. Blood pressure in the 3 dosing groups was analysed in the first 60 minutes after start of propofol.

RESULTS

Blood pressure declined after the start of propofol in all 3 dosing groups and was not restored 60 minutes after the start of propofol. The decline in blood pressure was highest in the 2.0 mg/kg dosing group. Blood pressure decline was mainly dependent on the initial propofol starting dose rather than the cumulative propofol dose.

CONCLUSION

Propofol causes a dose-dependent profound and prolonged decrease in blood pressure. The use of propofol should be carefully considered. When using propofol, starting with a low dose and titrating according to sedative effect seems the safest strategy.

Intervention and Outcome for Neonatal Hypotension

Many observational studies have shown that infants with blood pressures (BPs) that are in the lower range for their gestational age tend to have increased complications such as an increased rate of significant intraventricular hemorrhage and adverse long-term outcome. This relationship does not prove causation nor should it create an indication for treatment. However, many continue to intervene with medication for low BP on the assumption that an increase in BP will result in improved outcome. Only adequately powered prospective randomized controlled trials can answer the question of whether individual treatments of low BP are beneficial.

The Use of Cardiotonic Drugs in Neonates

There is a distinct lack of age-appropriate cardiotonic drugs, and adult derived formulations continue to be administered, without evidence-based knowledge on their dosing, safety, efficacy, and long-term effects. Dopamine remains the most commonly studied and prescribed cardiotonic drug in the neonatal intensive care unit (NICU), but evidence of its effect on endorgan perfusion still remains. Unlike adult and pediatric critical care, there are significant gaps in our knowledge on the use of various cardiotonic drugs in various forms of circulatory failure in the NICU.

Postnatal blood pressure in the preterm small for gestational age neonate

OBJECTIVE

Determine how blood pressure differs in premature infants born small for gestational age (SGA).

DESIGN

A retrospective study was conducted on inborn infants 24-32 weeks gestation. Mean arterial blood pressure (MAP) was collected and averaged every 12 h for the first 96 h of life. For each time point, the difference MAP in SGA vs. AGA infants was evaluated with t-testing. Linear mixed-effects modeling was performed to model MAP over time accounting for GA, BW, gender, and SGA status.

RESULTS

356 subjects were evaluated. 52 (14.6%) were SGA. SGA infants were smaller, more likely male, exposed to maternal hypertension, born via caesarian section, and have chronic lung disease and retinopathy of prematurity. MAP in the SGA group more closely matched the MAP of AGA babies of similar GA for the first 24 h of life. Subsequently, SGA infants had lower MAPs more closely resembling their weight-matched counterparts. Mixed modeling showed GA to be significant, p < 0.0001 while BW though still marginally significant had less of an effect, p = 0.049.

CONCLUSION

SGA infants have blood pressure that is strongly associated with GA in the first 24 hours of life, but then fails to increase at the same rate as their AGA counterparts.

Integrated Evaluation of Neonatal Hemodynamics Program Optimizing Organ Perfusion and Performance in Critically Ill Neonates, Part 1: Understanding Physiology of Neonatal Hemodynamics

Integrated evaluation of neonatal hemodynamics is the integration of information obtained by echocardiography, clinical evaluation, and biochemical markers, in addition to the clinical information obtained from noninvasive and invasive monitoring of blood pressure and arterial and tissue oxygenation, leading to the formulation of a medical recommendation. This review will focus on the physiology of cardiovascular dynamics and oxygen delivery.

Effects of Prophylactic Indomethacin on Vasopressor-Dependent Hypotension in Extremely Preterm Infants

OBJECTIVE

To determine whether a moderate-to-large patent ductus arteriosus (PDA) is responsible for vasopressor-dependent hypotension, occurring at the end of the first postnatal week.

STUDY DESIGN

We performed a retrospective, double cohort controlled study of infants delivered at ≤27+6 weeks' gestation (n = 313). From January 2004 through April 2011, all infants were treated with prophylactic indomethacin ([PINDO] epoch). From May 2011 through December 2015, no infant was treated with indomethacin until at least 8 postnatal days (conservative epoch). Echocardiograms were performed on postnatal days 6 or 7. Hypotension was managed by a predefined protocol. The primary outcome was the incidence of dopamine-dependent hypotension, defined as having received at least 6 µg/kg/min dopamine for at least 24 hours during postnatal days 4-7.

RESULTS

As expected, the incidence of moderate-to-large PDA at the end of the first week differed significantly between epochs (PINDO = 8%; conservative = 64%). In multivariate analyses, infants in the PINDO epoch had a significantly lower incidence of vasopressor-dependent hypotension (11%) than infants in the conservative epoch (21%; OR = 0.40, 95% CI 0.20-0.82). Infants in the PINDO epoch also required less mean airway pressure, had a lower respiratory severity score, and lower mode of ventilation score than infants in the conservative epoch during postnatal days 4-7. The effects of PINDO on both the incidence of vasopressor-dependent hypotension and the need for respiratory support were no longer significant when analyses were adjusted for "presence or absence of a moderate-to-large PDA."

CONCLUSION

PINDO decreases vasopressor-dependent hypotension and the need for respiratory support at the end of the first postnatal week. These effects are mediated by closure of the PDA.

Monitoring Cerebral Oxygenation in Neonates: An Update

Cerebral oxygenation is not always reflected by systemic arterial oxygenation. Therefore, regional cerebral oxygen saturation (rScO₂) monitoring with near-infrared spectroscopy (NIRS) is of added value in neonatal intensive care. rScO₂ represents oxygen supply to the brain, while cerebral fractional tissue oxygen extraction, which is the ratio between rScO₂ and systemic arterial oxygen saturation, reflects cerebral oxygen utilization. The balance between oxygen supply and utilization provides insight in neonatal cerebral (patho-)physiology. This review highlights the potential and limitations of cerebral oxygenation monitoring with NIRS in the neonatal intensive care unit.

Noradrenaline in preterm infants with cardiovascular compromise

Noradrenaline (NA) is beneficial in the treatment of term newborns with cardiovascular compromise due to sepsis or pulmonary hypertension, but experiences with NA in preterm infants are limited. The aim of this study is to describe the efficacy and safety of NA in preterm infants. Patient records of preterm infants ≤32 weeks' gestation admitted to two hospitals between 2004 and 2015 and who received NA were reviewed for perinatal morbidities and mortality. Clinical details were collected at the time of NA use, and response on blood pressure, perfusion and oxygenation was documented as well as possible side effects. Forty-eight infants with primary diagnoses of sepsis (63 %) and pulmonary hypertension (23 %) received NA. Normotension was achieved at a median of 1 h in all but one infant at a median dose of 0.5 mcg/kg/min. Infants who died (46 %) were of younger gestational age and had worse cardiovascular function at start of NA compared to infants who survived. Tachycardia was common (31 %), but no additional effects were found on kidney or liver function.

CONCLUSION

NA appears to be tolerated safely by preterm infants with no major side effects. However, effectiveness needs to be studies further in structured trials. What is Known: • Noradrenaline is beneficial in the treatment of term newborns and infants with cardiovascular compromise. • Noradrenaline is known for its potent vasoconstrictive effects and, therefore, infrequently used in preterm infants. What is New: • Noradrenaline used in relative low dose and as first or second line support increases blood pressure in preterm infants with cardiovascular compromise. • Tachycardia was common, but no additional side effects were found.

Non-dialytic management of acute kidney injury in newborns

Treating acute kidney injury (AKI) in newborns is often challenging due to the functional immaturity of the neonatal kidney. Because of this physiological limitation, renal replacement therapy (RRT) in this particular patient population is difficult to execute and may lead to unwanted complications. Although fluid overload and electrolyte abnormalities, as seen in neonatal AKI, are indications for RRT initiation, there is limited evidence that RRT initiated in the first year of life improves long-term outcome. The underlying cause of AKI in a newborn patient should determine the treatment strategies to restore appropriate renal function. However, our understanding of this common clinical condition remains limited, as no standardized, evidence-based definition of neonatal AKI currently exists. Non-dialytic management of AKI in these patients may restore appropriate renal function to these patients without exposure to complications often encountered with RRT.

Neonatal haemodynamic effects following foetal exposure to labetalol in hypertensive disorders of pregnancy

OBJECTIVE

Hypertensive disorders of pregnancy (HDP) affect foetal outcome. Labetalol is frequently used to lower maternal blood pressure and prolong pregnancy. Conflicting evidence exists for specific neonatal side effects described after maternal labetalol treatment. Our aim was to investigate neonatal effects of foetal exposure to labetalol on cerebral oxygenation and extraction.

METHODS

In a prospective observational study, clinical characteristics, vital parameters and cerebral oxygen delivery and extraction were collected during the first 24 h of life in labetalol-exposed preterm neonates and compared with two control groups.

RESULTS

Twenty-two infants with a mean gestational age of 28.9 weeks, born from labetalol-treated mothers with HDP were included and matched with 22 infants with non-labetalol-treated mothers with HDP and 22 infants without maternal HDP. No significant differences between groups were found neither in heart rate, blood pressure and inotropic support, nor in mean regional cerebral oxygen saturation and fractional tissue oxygen extraction.

CONCLUSION

Foetal labetalol exposure associated effects on preterm heart rate, blood pressure, cerebral oxygenation and extraction are not demonstrated. Maternal disease severity seems to play a more important role in neonatal cerebral haemodynamics. Maternal labetalol treatment has no clinically important short term side effects in the preterm neonate.

Early blood pressure, antihypotensive therapy and outcomes at 18-22 months' corrected age in extremely preterm infants

OBJECTIVE

To investigate the relationships between early blood pressure (BP) changes, receipt of antihypotensive therapy and 18-22 months' corrected age (CA) outcomes for extremely preterm infants.

DESIGN

Prospective observational study of infants 23(0/7)-26(6/7) weeks' gestational age (GA). Hourly BP values and antihypotensive therapy exposure in the first 24 h were recorded. Four groups were defined: infants who did or did not receive antihypotensive therapy in whom BP did or did not rise at the expected rate (defined as an increase in the mean arterial BP of ≥5 mm Hg/day). Random-intercept logistic modelling controlling for centre clustering, GA and illness severity was used to investigate the relationship between BP, antihypotensive therapies and infant outcomes.

SETTING

Sixteen academic centres of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network.

MAIN OUTCOME MEASURES

Death or neurodevelopmental impairment/developmental delay (NIDD) at 18-22 months' CA.

RESULTS

Of 367 infants, 203 (55%) received an antihypotensive therapy, 272 (74%) survived to discharge and 331 (90%) had a known outcome at 18-22 months' CA. With logistic regression, there was an increased risk of death/NIDD with antihypotensive therapy versus no treatment (OR 1.836, 95% CI 1.092 to 3.086), but not NIDD alone (OR 1.53, 95% CI 0.708 to 3.307).

CONCLUSIONS

Independent of early BP changes, antihypotensive therapy exposure was associated with an increased risk of death/NIDD at 18-22 months' CA when controlling for risk factors known to affect survival and neurodevelopment.

CLINICAL TRIAL REGISTRATION NUMBER

clinicaltrials.gov #NCT00874393.

Management during the first 72 h of age of the periviable infant: an evidence-based review

After NICU admission the extremely immature newborn (EIN) requires evaluation and support of each organ system, and the integration of all those supports in a comprehensive plan of care. In this review, I attempt to analyze the evidence for treatment options after the initial transition, during the first 3 days of life, which have been shown to improve survival or short- or long-term morbidity. This review revealed several things: there is little available evidence from studies that have included significant numbers of EINs; interventions affecting different organ systems need to be co-ordinated as any intervention will have multiple effects; and future advances in treatment of this group of patients will require the installation of permanent research networks to have enough power to perform many studies needed to improve outcomes.

Antecedents of perinatal cerebral white matter damage with and without intraventricular hemorrhage in very preterm newborns

BACKGROUND

Isolated periventricular leukomalacia, defined as periventricular leukomalacia unaccompanied by intraventricular hemorrhage, is reportedly increased in newborns with systemic hypotension and in infants who received treatment for systemic hypotension or a patent ductus arteriosus.

METHODS

This study sought to determine if the risk profile of one or more hypoechoic lesions unaccompanied by intraventricular hemorrhage, our surrogate for isolated periventricular leukomalacia, differs from that of one or more hypoechoic lesions preceded or accompanied by intraventricular hemorrhage. We compared extremely preterm infants (i.e., gestation 23-27 weeks) with each of these entities to 885 extremely preterm infants who had neither an isolated hypoechoic lesion nor a hypoechoic lesion preceded or accompanied by intraventricular hemorrhage.

RESULTS

The risk of a hypoechoic lesion with intraventricular hemorrhage (N = 61) was associated with gestation <25 weeks, high Score for Acute Neonatal Physiology, early recurrent or prolonged acidemia, analgesic exposure, and mechanical ventilation 1 week after birth.

CONCLUSIONS

In this large, multicenter sample of extremely low gestational age newborns, the risk profile of a hypoechoic lesion unaccompanied by intraventricular hemorrhage differed from that of a hypoechoic lesion with intraventricular hemorrhage. This suggests that hypoechoic lesions accompanied or preceded by intraventricular hemorrhage (our surrogate for periventricular hemorrhagic infarction) may have a different causal pathway than hypoechoic lesions without intraventricular hemorrhage, our surrogate for periventricular leukomalacia.

Persistent pulmonary hypertension of the newborn: recent advances in pathophysiology and treatment

OBJECTIVES

Although recognized for decades, little is known about the etiology, physiopathology, and prevention of persistent pulmonary hypertension of the newborn (PPHN), and its treatment remains a major challenge for neonatologists. In this review, the clinical features and physiopathology of the syndrome will be addressed, as well as its general and specific treatments.

DATA SOURCE

A review was carried out in PubMed, Cochrane Library, and MRei consult databases, searching for articles related to the syndrome and published between 1995 and 2011.

DATA SYNTHESIS

Risk factors and the physiopathological mechanisms of the syndrome are discussed. The clinical presentation depends on the different factors involved. These are related to the etiology and physiopathology of the different forms of the disease. In addition to the measures used to allow for the decrease in pulmonary vascular resistance after birth, in some instances pulmonary vasodilators will be required. Although inhaled nitric oxide has proved effective, other vasodilators have been recently used, but clinical evidence is still lacking to demonstrate their benefits in the treatment of PPHN.

CONCLUSIONS

Despite recent technological advances and new physiopathological knowledge of this disease, mortality associated with PPHN remains at 10%. More clinical research and evidence-based experimental results are needed to prevent, treat, and reduce the morbidity/mortality associated with this neonatal syndrome.

Left ventricular output and aortic blood flow in response to changes in preload and afterload in the preterm piglet heart

Low systemic blood flow occurs in up to 30% of infants born at less than 30 wk gestation. It is associated with increased morbidity and mortality, and current treatments are ineffective in 40% of cases. The aim of this study was to assess the ability of the preterm heart to respond to the acute shifts in preload and afterload that occur at the time of birth. Myocardial and coronary vascular function was assessed using an isolated working heart model in term (115 days) and preterm (92 days) piglets. Cardiac output/kg body wt in preterm hearts was ∼50% lower than that of term hearts (P = 0.001). Pressure development was similar in term and preterm hearts. Elevations in preload increased cardiac output and aortic flow similarly in term and preterm hearts, demonstrating significant preload "reserve". By contrast, elevations in afterload markedly depressed aortic flow, with a greater proportion of cardiac output being distributed to coronary flow in preterm hearts at high afterloads. The demands of increased workload were associated with greater increases in coronary flow in preterm hearts compared with term hearts. In preterm hearts, exposure to maternal glucocorticoids resulted in increased aortic flow when afterload was below 25 mmHg. These data suggest the preterm heart lacks the functional capacity to acutely adapt to postnatal afterload. To maximize systemic blood flow in preterm infants, treatments limiting afterload, while harnessing significant preload reserve, should be further explored.

Blood pressure support in the very low-birth-weight infant during the first week of life

The immature cardiovascular system of very preterm infants predisposes them to low systemic blood flow during the first week of life, a state that may be damaging to multiple organ systems. There are many treatment strategies for the maintenance of cardiovascular equilibrium in these infants, each with its own advantages and risks. Caregivers are responsible for assessing the circulatory status of each patient and evaluating the effectiveness of interventions aimed at maintaining adequate systemic blood flow. Therefore, it is important to have an understanding of the mechanics of transitional circulation, the relationship between blood pressure and systemic blood flow, and the therapies used to treat infants with compromised organ perfusion.

Propranolol inhibition of β-adrenergic receptor does not suppress pathologic neovascularization in oxygen-induced retinopathy

PURPOSE

Retinopathy of prematurity (ROP) is a leading cause of blindness in children and is, in its most severe form, characterized by uncontrolled growth of vision-threatening pathologic vessels. Propranolol, a nonselective β-adrenergic receptor blocker, was reported to protect against pathologic retinal neovascularization in a mouse model of oxygen-induced retinopathy (OIR). Based on this single animal study using nonstandard evaluation of retinopathy, clinical trials are currently ongoing to evaluate propranolol treatment in stage 2 ROP patients who tend to experience spontaneous disease regression and are at low risk of blindness. Because these ROP patients are vulnerable premature infants who are still in a fragile state of incomplete development, the efficacy of propranolol treatment in retinopathy needs to be evaluated thoroughly in preclinical animal models of retinopathy and potential benefits weighed against potential adverse effects.

METHODS

Retinopathy was induced by exposing neonatal mice to 75% oxygen from postnatal day (P) 7 to P12. Three routes of propranolol treatment were assessed from P12 to P16: oral gavage, intraperitoneal injection, or subcutaneous injection, with doses varying between 2 and 60 mg/kg/day. At P17, retinal flatmounts were stained with isolectin and quantified with a standard protocol to measure vasoobliteration and pathologic neovascularization. Retinal gene expression was analyzed with qRT-PCR using RNA isolated from retinas of control and propranolol-treated pups.

RESULTS

None of the treatment approaches at any dose of propranolol (up to 60 mg/kg/day) were effective in preventing the development of retinopathy in a mouse model of OIR, evaluated using standard techniques. Propranolol treatment also did not change retinal expression of angiogenic factors including vascular endothelial growth factor.

CONCLUSIONS

Propranolol treatment via three routes and up to 30 times the standard human dose failed to suppress retinopathy development in mice. These data bring into question whether propranolol through inhibition of β-adrenergic receptors is an appropriate therapeutic approach for treating ROP.

Neonatal drug development

Drug development is crucial to improving the care given to neonates through new and existing medicines. Pressure from regulatory agencies has improved the way in which pharmaceutical companies work with neonates. This provides new opportunities for the neonatal community. This paper describes the issues that arise during the development of new drugs and considers how the contemporary approach to new drugs can inform research on existing drugs.

On the use of antiangiogenetic medications for retinopathy of prematurity

In contrast to the adult, the third-trimester foetus experiences one of the most intense periods of growth and maturation of its lifetime. Early development is characterized by the existence of critical periods when environmental factors effectively produce long-lasting changes. Proliferative retinopathy of prematurity (ROP) is a potentially blinding disease characterized by uncontrolled retinal angiogenesis. This pathologic angiogenesis is the target for two new treatment modalities for ROP, i.e. intravitreal anti-VEGF (bevacizumab) and systemic propranolol, which are being evaluated in ongoing or planned studies. VEGF is essential for normal angiogenesis in a growing infant, and the adrenergic system is important for many organ systems and, in addition, for plasticity of the visual and olfactory systems.

CONCLUSION

This viewpoint raises concerns regarding the currently studied antiangiogenetic treatments for ROP and their possible general effects on the developing preterm infant.

Early postnatal hypotension is not associated with indicators of white matter damage or cerebral palsy in extremely low gestational age newborns

OBJECTIVE

To evaluate, in extremely low gestational age newborns (ELGANs), relationships between indicators of early postnatal hypotension and cranial ultrasound indicators of cerebral white matter damage imaged in the nursery and cerebral palsy diagnoses at 24 months follow-up.

STUDY DESIGN

The 1041 infants in this prospective study were born at <28 weeks gestation, were assessed for three indicators of hypotension in the first 24 postnatal hours, had at least one set of protocol cranial ultrasound scans and were evaluated with a structured neurological exam at 24 months corrected age. Indicators of hypotension included: (1) lowest mean arterial pressure (MAP) in the lowest quartile for gestational age; (2) treatment with a vasopressor; and (3) blood pressure lability, defined as the upper quartile of the difference between each infant's lowest and highest MAP. Outcomes included indicators of cerebral white matter damage, that is, moderate/severe ventriculomegaly or an echolucent lesion on cranial ultrasound and cerebral palsy diagnoses at 24 months gestation. Logistic regression was used to evaluate relationships among hypotension indicators and outcomes, adjusting for potential confounders.

RESULT

Twenty-one percent of surviving infants had a lowest blood pressure in the lowest quartile for gestational age, 24% were treated with vasopressors and 24% had labile blood pressure. Among infants with these hypotension indicators, 10% percent developed ventriculomegaly and 7% developed an echolucent lesion. At 24 months follow-up, 6% had developed quadriparesis, 4% diparesis and 2% hemiparesis. After adjusting for confounders, we found no association between indicators of hypotension, and indicators of cerebral white matter damage or a cerebral palsy diagnosis.

CONCLUSION

The absence of an association between indicators of hypotension and cerebral white matter damage and or cerebral palsy suggests that early hypotension may not be important in the pathogenesis of brain injury in ELGANs.

Postnatal steroids for the treatment of bronchopulmonary dysplasia: a complex case presentation

Postnatal steroids are a controversial intervention for the prevention and treatment of bronchopulmonary dysplasia in preterm infants. Studies demonstrating a potential for steroid-related adverse effects, including growth and neurodevelopmental impairment, have significantly changed clinical practice over the past decade. There are circumstances in which the potential benefits may outweigh the risks associated with postnatal steroids. This case presentation details the hospital course and treatment plan for an extremely low-birth-weight infant who remained ventilator dependent at the age of 3 weeks. Evidence-based research, American Academy of Pediatric recommendations, and collaboration with the family helped guide the plan of care. Following a short course of low-dose dexamethasone, the infant was successfully extubated. The case highlights the importance of using clinical judgment based on research and family preferences to benefit the patient.

Association of necrotizing enterocolitis with anemia and packed red blood cell transfusions in preterm infants

OBJECTIVE

To determine association of anemia and red blood cell (RBC) transfusions with necrotizing enterocolitis (NEC) in preterm infants.

STUDY DESIGN

A total of 111 preterm infants with NEC ≥ stage 2a were compared with 222 matched controls. In all, 28 clinical variables, including hematocrit (Hct) and RBC transfusions were recorded. Propensity scores and multivariate logistic regression models were created to examine effects on the risk of NEC.

RESULT

Controlling for other factors, lower Hct was associated with increased odds of NEC (odds ratio (OR)=1.10, P=0.01). RBC transfusion has a temporal relationship with NEC onset. Transfusion within 24 h (OR=7.60, P=0.001) and 48 h (OR=5.55, P=0.001) has a higher odds of developing NEC but this association is not significant by 96 h (OR=2.13, P=0.07), post-transfusion.

CONCLUSION

Anemia may increase the risk of developing NEC in preterm infants. RBC transfusions are temporally related to NEC. Prospective studies are needed to better evaluate the potential influence of transfusions on the development of NEC.

The need for noninvasive biomarkers for drug safety in neonatal circulation

The new EU Pediatric Drug Regulation covers the development of new drugs to include studies in children and newborn babies. An important part of the evaluation of a new drug will be data on efficacy and safety related to short-term and possible long-term effects. Owing to the special circumstances of studying drugs, especially in newborn babies, new, preferably noninvasive, biomarkers are required that can be used for assessment and monitoring in this vulnerable patient population. Feedback from expert groups and public stakeholders should be taken into account when introducing biomarkers into the study design. New noninvasive biomarkers for monitoring cardiovascular circulation in newborns will be used to illustrate an example of their practical use and implementation.