Neonatal blood pressure support: the use of inotropes, lusitropes, and other vasopressor agents

Cardiac Development and Related Clinical Considerations

The anatomy, physiology, and hemodynamics of the premature heart vary along the range of gestational ages cared for in neonatal intensive care units, from 22 weeks to term gestation. Clinical management of the preterm neonate should account for this heterogenous development. This requires an understanding of the impact of ex utero stressors on immature and disorganized cardiac tissue, the different state of hemodynamics across intracardiac shunts impacting the natural transition from fetal to neonatal life, and the effects of intensive pharmacologic and non-pharmacologic interventions that have systemic consequences influencing cardiac function. This article provides a review of the increasing but still limited body of literature on the anatomy, hemodynamics, and electrophysiology of the preterm heart with relevant clinical considerations.

An Update on Pharmacologic Management of Neonatal Hypotension: When, Why, and Which Medication

Anti-hypotensive treatment, which includes dopamine, dobutamine, epinephrine, norepinephrine, milrinone, vasopressin, terlipressin, levosimendan, and glucocorticoids, is a long-established intervention in neonates with arterial hypotension (AH). However, there are still gaps in knowledge and issues that need clarification. The main questions and challenges that neonatologists face relate to the reference ranges of arterial blood pressure in presumably healthy neonates in relation to gestational and postnatal age; the arterial blood pressure level that potentially affects perfusion of critical organs; the incorporation of targeted echocardiography and near-infrared spectroscopy for assessing heart function and cerebral perfusion in clinical practice; the indication, timing, and choice of medication for each individual patient; the limited randomized clinical trials in neonates with sometimes conflicting results; and the sparse data regarding the potential effect of early hypotension or anti-hypotensive medications on long-term neurodevelopment. In this review, after a short review of AH definitions used in neonates and existing data on pathophysiology of AH, we discuss currently available data on pharmacokinetic and hemodynamic effects, as well as the effectiveness and safety of anti-hypotensive medications in neonates. In addition, data on the comparisons between anti-hypotensive medications and current suggestions for the main indications of each medication are discussed.

Reflecting on the 1998 enterovirus outbreak: A 25-year retrospective and learned lessons

Enterovirus A71 (EV-A71) infections pose a significant public health concern in the Asia-Pacific region. EV-A71 is primarily responsible for causing hand, foot, and mouth disease (HFMD) in children. However, this virus can also lead to severe and potentially fatal neurological consequences in affected individuals. This review aims to provide a comprehensive understanding of the molecular virology, epidemiology, and recombination events associated with EV-A71. The literature extensively covers the clinical manifestations and neurological symptoms that accompany EV-A71 infections. One of the complications explored in this review is brainstem encephalitis, which can arise as a result of EV-A71 infections. Brainstem encephalitis refers to inflammation of the brainstem, a critical region responsible for various bodily functions. The review examines the underlying mechanisms, diagnostic criteria, treatment options, and prognosis for central nervous system infections involving EV-A71. Neurological complications associated with EV-A71 infections are diverse and can have severe consequences. These complications may include aseptic meningitis, acute flaccid paralysis, and acute transverse myelitis. The review delves into the pathophysiology of these complications, shedding light on the molecular mechanisms through which EV-A71 affects the central nervous system. Accurate diagnosis of EV-A71 infections is crucial for appropriate management and treatment. Treatment options for EV-A71 infections primarily focus on supportive care, as there are currently no specific antiviral drugs available for this virus. The review highlights the importance of managing symptoms, such as fever, dehydration, and pain relief, to alleviate the burden on affected individuals. Prognosis for individuals with central nervous system (CNS) infections involving EV-A71 can vary depending on the severity of the complications. The review provides insights into the long-term outcomes and potential neurological sequelae associated with EV-A71 infections. In conclusion, EV-A71 infections have emerged as a major public health concern in the Asia-Pacific region. This review aims to enhance our understanding of the molecular virology, epidemiology, and neurological complications associated with EV-A71. By examining the underlying mechanisms, diagnostic criteria, treatment options, and prognosis, this review contributes to the development of effective strategies for the prevention, diagnosis, and management of EV-A71 infections. The paper presents a comprehensive analysis of worldwide data pertaining to outbreaks of EV-A71 and HFMD. The subsequent discourse delves into the advancement and strategic formulation pertaining to the creation of vaccines targeting EV-A71. In summary, this study provides a comprehensive examination of the potential obstacles and considerations involved in the management and treatment of EV-A71 infections. Additionally, it proposes suggestions for future research and development endeavors with the objective of formulating efficacious treatment approaches for this viral infection.

Effects of Milrinone on Neonates after Patent Ductus Arteriosus Ligation: A Retrospective Nationwide Database Study

INTRODUCTION

Milrinone is administered after patent ductus arteriosus (PDA) ligation to prevent and treat postoperative hemodynamic instability (i.e., postligation cardiac syndrome). We aimed to explore the effectiveness of milrinone on in-hospital outcomes in infants who underwent PDA ligation using a nationwide inpatient database in Japan.

METHODS

Using the Japanese Diagnosis Procedure Combination database, we identified patients who received milrinone after PDA ligation (n = 428) in neonatal intensive care units between July 2010 and March 2021 and those who did not (n = 3,392). We conducted a 1:4 propensity score-matched analysis with adjustment for background characteristics (e.g., gestational age, birth weight, comorbidities, preoperative treatments, and hospital background) to compare morbidities (bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and retinopathy of prematurity), mortality, total hospitalization costs, and other outcomes. For sensitivity analysis, we performed an overlap propensity score-weighted analysis.

RESULTS

In-hospital morbidity, bronchopulmonary dysplasia, intraventricular hemorrhage, and necrotizing enterocolitis occurred in 58%, 48%, 9.5%, and 7.1% of patients, respectively; the in-hospital mortality was 5.4%. After 1:4 propensity score matching, no significant difference was observed regarding mortality (7.1 vs. 5.7%), in-hospital morbidity (55 vs. 50%), bronchopulmonary dysplasia (44 vs. 41%), intraventricular hemorrhage (7.8 vs. 9.1%), necrotizing enterocolitis (8.5 vs. 8.9%), retinopathy of prematurity (21 vs. 22%), or total hospitalization costs (median: approximately 86,000 vs. 82,000 US dollars) between milrinone users (n = 425) and nonusers (n = 1,698). Sensitivity analyses yielded consistent results.

CONCLUSIONS

Milrinone use after PDA ligation was not associated with improved in-hospital outcomes, such as mortality and morbidity.

Use of Vasopressors in Extremely Preterm Infants in First Week of Life

OBJECTIVE

 A significant variability exists for diagnosis and treatment of hypotension in extremely preterm infants. Benefits of the use of vasopressors remain unclear. We wanted to identify the risk factors associated with use of vasopressors in the first week of life and their impact on outcomes of extremely preterm infants.

STUDY DESIGN

 Retrospective review of all newborns ≤28 weeks of gestational age (GA) admitted in neonatal intensive care unit from October 1, 2012, to October 31, 2015, done. Data regarding antenatal and neonatal characteristics and outcomes were recorded. Study infants were divided into two cohorts and compared based on vasopressor use. Chi-square, t-test, and multiple logistic regression were performed as appropriate and significance set at p <0.05.

RESULTS

 Of 213 extremely preterm infants, 90 (42.3%) received vasopressors in first week of life. The mean arterial pressure (MAP) at admission in these infants was significantly lower than that of infants who did not require vasopressors (27 ± 8 vs. 30 ± 6 mm Hg, p < 0.05). Vasopressors were initiated within 24 hours in 91% of babies. After controlling for other variables, use of vasopressors was significantly higher in infants with lower birth weight (odds ratio [OR]: 3.2, 95% confidence interval [CI]: 1.6-8.3), 5-minute Apgar's score ≤5 (OR: 1.8, 95% CI: 1.2-3.12), and admission hypothermia (OR: 2.7, 95% CI: 1.3-4.9). The use of vasopressors was significantly associated with severe intraventricular hemorrhage (IVH), even after controlling for other significant variables (OR: 5.9, 95% CI: 1.6-9.3).

CONCLUSION

 Lower birth weight, low 5-minute Apgar's score, and admission hypothermia are characteristics associated with early use of vasopressors in extremely preterm infants. Infants treated with vasopressors are at a higher risk of developing severe IVH.

KEY POINTS

· Low systemic blood pressure is a very common problem in the extremely preterm population.. · In clinical practice, mean arterial blood pressure (BP) less than the infants GA in week is typically considered to be "low BP.". · About 50% of infants born at <29 weeks of GA received very preterm in the first week of life.. · Use of vasopressors is associated with a higher incidence of intraventricular hemorrhage in extremely preterm population..

Near-infrared spectroscopy monitoring of neonatal cerebrovascular reactivity: where are we now?

Cerebrovascular reactivity defines the ability of the cerebral vasculature to regulate its resistance in response to both local and systemic factors to ensure an adequate cerebral blood flow to meet the metabolic demands of the brain. The increasing adoption of near-infrared spectroscopy (NIRS) for non-invasive monitoring of cerebral oxygenation and perfusion allowed investigation of the mechanisms underlying cerebrovascular reactivity in the neonatal population, confirming important associations with pathological conditions including the development of brain injury and adverse neurodevelopmental outcomes. However, the current literature on neonatal cerebrovascular reactivity is mainly still based on small, observational studies and is characterised by methodological heterogeneity; this has hindered the routine application of NIRS-based monitoring of cerebrovascular reactivity to identify infants most at risk of brain injury. This review aims (1) to provide an updated review on neonatal cerebrovascular reactivity, assessed using NIRS; (2) to identify critical points that need to be addressed with targeted research; and (3) to propose feasibility trials in order to fill the current knowledge gaps and to possibly develop a preventive or curative approach for preterm brain injury. IMPACT: NIRS monitoring has been largely applied in neonatal research to assess cerebrovascular reactivity in response to blood pressure, PaCO₂ and other biochemical or metabolic factors, providing novel insights into the pathophysiological mechanisms underlying cerebral blood flow regulation. Despite these insights, the current literature shows important pitfalls that would benefit to be addressed in a series of targeted trials, proposed in the present review, in order to translate the assessment of cerebrovascular reactivity into routine monitoring in neonatal clinical practice.

Vein of Galen aneurysmal malformation: rationalizing medical management of neonatal heart failure

Neonates who present in high output heart failure secondary to vein of Galen aneurysmal malformation can be difficult to manage medically due to the complex physiology that results from the large shunt through the malformation. Though the cardiac function is often normal, right ventricular dilation, severe pulmonary hypertension, and systemic steal can result in inadequate organ perfusion and shock. This report recommends medical management for stabilization of neonates prior to definitive management with endovascular embolization. IMPACT: Vein of Galen aneurysmal malformation (VGAM) is a rare intracranial arteriovenous malformation, which can present in the neonatal period with high output heart failure. Heart failure secondary to VGAM is often difficult to manage and is associated with high mortality and morbidity. Despite optimal medical management, many patients require urgent endovascular embolization for stabilization of their heart failure. This report offers discrete recommendations that can be used by clinicians as guidelines for the medical management of heart failure in newborns with VGAM.

Calcium Responsive Pediatric Septic Shock Refractory to Isotonic Crystalloids and Inotropic Agents

Pediatric septic shock is a life-threatening condition with significant rates of morbidity and mortality. Standard management includes fluid resuscitation, timely antimicrobial administration, and epinephrine or norepinephrine if unresolved with initial management. Additional therapies are not well defined and include vasopressin, hydrocortisone, phenylephrine, levosimendan, dopamine, and others. Many of these agents modify cellular effects of calcium in the smooth muscle. The use of a calcium infusion may improve vasoactivity in the smooth muscle without the use of signaling pathways. Children are more susceptible to the effects of calcium, which may predispose them to enhanced vasoconstriction with the administration of intravenous calcium. We present a case in which a patient on chronic calcium channel blocker therapy presented with septic shock. She continued to remain hypotensive after fluid resuscitation, antibiotics, epinephrine, and norepinephrine. Her blood pressure improved with the initiation of a continuous calcium chloride infusion. Norepinephrine and epinephrine doses were decreased after the initiation of the calcium infusion.

Acute Cardiac Care for Neonatal Heart Disease

This manuscript is one component of a larger series of articles produced by the Neonatal Cardiac Care Collaborative that are published in this supplement of Pediatrics. In this review article, we summarize the contemporary physiologic principles, evaluation, and management of acute care issues for neonates with complex congenital heart disease. A multidisciplinary team of authors was created by the Collaborative's Executive Committee. The authors developed a detailed outline of the manuscript, and small teams of authors were assigned to draft specific sections. The authors reviewed the literature, with a focus on original manuscripts published in the last decade, and drafted preliminary content and recommendations. All authors subsequently reviewed and edited the entire manuscript until a consensus was achieved. Topics addressed include cardiopulmonary interactions, the pathophysiology of and strategies to minimize the development of ventilator-induced low cardiac output syndrome, common postoperative physiologies, perioperative bleeding and coagulation, and common postoperative complications.

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.

Clinical determinants of cerebrovascular reactivity in very preterm infants during the transitional period

BACKGROUND

Preterm infants are at enhanced risk of brain injury due to altered cerebral haemodynamics during postnatal transition. This observational study aimed to assess the clinical determinants of transitional cerebrovascular reactivity and its association with intraventricular haemorrhage (IVH).

METHODS

Preterm infants <32 weeks underwent continuous monitoring of cerebral oxygenation and heart rate over the first 72 h after birth. Serial cranial and cardiac ultrasound assessments were performed to evaluate the ductal status and to diagnose IVH onset. The moving correlation coefficient between cerebral oxygenation and heart rate (TOHRx) was calculated. Linear mixed-effect models were used to analyse the impact of relevant clinical variables on TOHRx. The association between TOHRx and IVH development was also assessed.

RESULTS

Seventy-seven infants were included. A haemodynamically significant patent ductus arteriosus (hsPDA) (β = 0.044, 95% CI: 0.007-0.081) and ongoing dopamine treatment (β = 0.096, 95% CI: 0.032-0.159) were associated with increasing TOHRx, indicating impaired cerebrovascular reactivity. A significant association between TOHRx, mean arterial blood pressure (β = -0.004, 95% CI: -0.007, -0.001) and CRIB-II score (β = 0.007, 95% CI: 0.001-0.015) was also observed. TOHRx was significantly higher in infants developing high-grade IVH compared to those without IVH.

CONCLUSIONS

Dopamine treatment, low blood pressure, hsPDA and high CRIB-II are associated with impaired cerebrovascular reactivity during postnatal transition, with potential implications on IVH development.

IMPACT

The correlation coefficient between cerebral oxygenation and heart rate (TOHRx) provides a non-invasive estimation of cerebrovascular reactivity, whose failure has a potential pathogenic role in the development of IVH in preterm infants. This study shows that cerebrovascular reactivity during the transitional period improves over time and is affected by specific clinical and therapeutic factors, whose knowledge could support the development of individualized neuroprotective strategies in at-risk preterm infants. The evidence of increased TOHRx in infants developing high-grade compared to low-grade or no IVH during the transitional period further supports the role of impaired cerebrovascular reactivity in IVH pathophysiology.

The effect of norepinephrine on clinical and hemodynamic parameters in neonates with shock: a retrospective cohort study

There is limited data on the cardiovascular effects of norepinephrine (NE) in neonates. Our objective was to describe the clinical responses in neonates treated with NE infusion. This retrospective cohort study included neonates with evidence of shock and those who received NE infusion.

PRIMARY OUTCOME

changes in mean blood pressure (MBP) at 6, 12, and 24 h post-initiation of NE.

SECONDARY OUTCOMES

Changes in (i) diastolic BP, systolic BP, and vasoactive inotrope score (VIS) at 6, 12, and 24 h, (ii) urine output after initiation of NE ii) pH, lactate, fraction of inspired oxygen (FiO2) after initiation of NE, and (iv) adverse outcomes. Fifty infants received NE with mean (SD) gestational age of 34.3 (4.3) weeks and a mean birth weight of 2215 (911) g. Treatment began at a median age of 36 (IQR: 15.2, 67.2) hours of life and lasted 30.5 (IQR: 12.7, 58) hours. MBP improved from 34.4 mm Hg (SD: 6.6) at baseline to 39.4 mm Hg (SD: 10.5, p < 0.001) at 6 h, to 39.6 mm Hg (SD: 12.1, p = 0.002) at 12 h and to 40.4 mm Hg (SD: 15.5, p = 0.004) at 24 h after NE initiation. Vasoactive inotrope score declined from 30 (20, 32) to 10 (4, 30; p < 0.001) at 24 h. Urine output improved within 24 h [1.5 ml/kg/h (0.5, 2.3) at baseline to 3 (1.9, 4.3) at 24 h; p = 0.04]. Oxygen requirement decreased after NE initiation.

CONCLUSION

The use of NE appears to be effective and safe for treating systemic hypotension in neonates.

TRIAL REGISTRATION

Being a retrospective study, trial registration was not considered.

WHAT IS KNOWN

• Dopamine has traditionally been used as the initial agent for treatment of neonatal hypotension. • Norepinephrine has recently been recommended as the first-choice vasopressor agent to correct hypotension in adults and pediatric patients, with insufficient data on the cardiovascular effects of NE in neonates What is new: • Mean blood pressure improved significantly at 6, 12, and 24 h with reduction in vasoactive infusion score at 12 and 24 h after norepinephrine infusion. • No significant change in heart rate or abnormal abdominal adverse effects noted in this study.

Recognition and Management of Cardiovascular Insufficiency in the Very Low Birth Weight Newborn

The measurement of blood pressure in the very low birth weight newborn infant is not simple and may be erroneous because of numerous factors. Assessment of cardiovascular insufficiency in this population should be based on multiple parameters and not only on numeric blood pressure readings. The decision to treat cardiovascular insufficiency should be made after considering the potential complications of such treatment. There are numerous potential strategies to avoid or mitigate hypoperfusion states in the very low birth weight infant.

Which Inotropic Drug, Dobutamine or Milrinone, Is Clinically More Effective in the Treatment of Postligation Cardiac Syndrome in Preterm Infants?

OBJECTIVE

This study aimed to detect which of the two main medicines suggested in the treatment of postligation cardiac syndrome (PLCS)-dobutamine or mirinone-possesses a more therapeutic effect. While doing this, clinicians are provided with a broader perspective on the treatment and follow-up of cases. The desire was to increase the treatability and monitor ability of the cases in question and hence their survivability.

STUDY DESIGN

A retrospective review of a cohort of infants with PLCS was conducted between March 2012 and December 2018. In the treatment of infants with PLCS, dobutamine (dobutamine study group-DSG) or milrinone (milrinone study group-MSG) was used. The respiration, cardiac, echocardiography, and perfusion parameters of the cases were assessed both before and after ligation. Based on the data obtained, both the effects of the medicines on PLCS and the difference between their therapeutic effects were studied. The accuracy of prognostication was assessed with receiver operating characteristic analyses.

RESULTS

PLCS was detected in 29 (34.1%) of 85 patent ductus arteriosus ligation cases in total. Of all the PLCS cases, 13 (44.8%) were treated with dobutamine and 16 (55.2%) with milrinone. It was observed that the effects of the medicines on the respiratory system and cardiovascular system manifested in the third and 6th hour, respectively. It was detected that both medicines had more effect on the systolic blood pressure (SBP) (area under the curve [AUC]: 0.997/0.996, p = 0.001/0.002) than on the diastolic blood pressure (AUC: 0.911/0.843, p = 0.032/0.046).

CONCLUSION

Dobutamine and milrinone, two primary medicines that can be used in the treatment of cases with PLCS, possess similar therapeutic effects on this pathology. In addition, their postoperative therapeutic effects on the SBP are more in the foreground.

Hemodynamic monitoring and management of pediatric septic shock

Sepsis remains a major cause of morbidity and mortality among children worldwide. Furthermore, refractory septic shock and multiple organ dysfunction syndrome are the most critical groups which account for a high mortality rate in pediatric sepsis, and their clinical course often deteriorates rapidly. Resuscitation based on hemodynamics can provide objective values for identifying the severity of sepsis and monitoring the treatment response. Hemodynamics in sepsis can be divided into two groups: basic and advanced hemodynamic parameters. Previous therapeutic guidance of early-goal directed therapy (EGDT), which resuscitated based on the basic hemodynamics (central venous pressure and central venous oxygen saturation (ScvO2)) has lost its advantage compared with “usual care”. Optimization of advanced hemodynamics, such as cardiac output and systemic vascular resistance, has now been endorsed as better therapeutic guidance for sepsis. Despite this, there are still some important hemodynamics associated with prognosis. In this article, we summarize the common techniques for hemodynamic monitoring, list important hemodynamic parameters related to outcomes, and update evidence-based therapeutic recommendations for optimizing resuscitation in pediatric septic shock.

Vasoactive medications in extremely low gestational age neonates during the first postnatal week

OBJECTIVE

The management of early hypotension in extremely low gestational age neonates (ELGANs) varies greatly between centers. The objective of this study was to provide updated data on the use of vasoactive medications in ELGANs during the first postnatal week.

STUDY DESIGN

We identified ELGANs (22-27 weeks gestational age) cared for at Pediatrix neonatal intensive care units from 2009 to 2018. We evaluated the frequency of exposure to vasoactive medications by gestational age, and compared use of vasoactive medications between two epochs (2009-2013 and 2014-2018).

RESULTS

A total of 10,070/34,234 (29%) ELGANs received ≥1 vasoactive medication. Dopamine was the most frequently used vasoactive medication. The majority (83%) of treated ELGANs initiated therapy on postnatal days 0-1. Overall use of vasoactive medications was slightly lower in 2014-2018 than 2009-2013 (28 vs 31%, p < 0.001).

CONCLUSION

A substantial proportion of ELGANs were exposed to vasoactive medications during the first postnatal week.

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.

Recognition and management of neonatal hemodynamic compromise

Hemodynamic compromise of the neonate can occur in various clinical situations, including but not limited to maladaptation during the early transitional period, sepsis, congenital heart anomalies, hemodynamically significant patent ductus arteriosus, persistent pulmonary hypertension of the newborn, systemic inflammatory diseases such as necrotizing enterocolitis, and dehydration. Despite the handful of advances in neonatal care through ground-breaking clinical trials, the management of neonatal shock is often dependent on the bedside clinician's experience and training without the aid of high-level evidence. However, the recognition for the importance of comprehensive and serial hemodynamic assessment is growing. There is now a wealth of literature investigating the use of functional echocardiography, near-infrared spectroscopy, and noninvasive impedance-based cardiometry to complement common bedside hemodynamic measures such as blood pressure and heart rate measurement. In this review article, the pathophysiology of neonatal hemodynamic compromise is outlined, and concomitant best-evidence management for hemodynamic compromise in the neonate is proposed.

Milrinone Use in Persistent Pulmonary Hypertension of the Newborn

Failure of the normal transition from in utero to ex utero physiology leads to "persistent" pulmonary hypertension of the newborn (PPHN). PPHN is frequently associated with low systemic blood pressure and low cardiac output because of increased right ventricular afterload and myocardial dysfunction. The general management of newborns with PPHN is geared toward maintenance of normothermia, normal serum electrolytes, normal intravascular volume, correction of acidosis, adequate sedation/analgesia, adequate ventilation and oxygenation with optimal lung recruitment, and avoidance of hyperoxia. Inotropic and vasoactive agents are commonly initiated early to increase cardiac output, maintain adequate systemic blood pressure, and enhance oxygen delivery to the tissue. Unfortunately, there is not much evidence on the choice, timing of initiation, dosing, monitoring, and titrating of vasoactive agents in this patient population. In this review, we will discuss the pathophysiology of PPHN and review the use of inotropic, lusitropic, and vasoactive agents in the management of PPHN, with particular attention to milrinone.

Efficacy of Low-Dose Epinephrine Continuous Infusion in Neonatal Intensive Care Unit Patients

OBJECTIVES

Although epinephrine is used in the neonatal intensive care unit, few data exist on efficacy of doses <0.05 mcg/kg/min. This study evaluates the efficacy and safety of low-dose epinephrine continuous infusion at doses <0.05 mcg/kg/min in infants.

METHODS

Single-center, retrospective review of hypotensive infants from 2011-2018. Charts were reviewed for initial and maximum epinephrine doses, additional vasoactive agents, short-term efficacy, and adverse effects. The primary outcome was percentage of patients initiated on low-dose epinephrine whose dose did not require titration to ≥0.05 mcg/kg/min.

RESULTS

A total of 115 patients met study criteria with 131 distinct occurrences of low-dose epinephrine initiation. Most patients were unresponsive to other vasopressors at the time of epinephrine initiation. The median (IQR) starting dose of low-dose epinephrine was 0.01 (0.01-0.04) mcg/kg/min and median (IQR) maximum dose was 0.04 (0.02-0.08) mcg/kg/min. Fifty-five percent were responders. Patients in this cohort demonstrated significant improvement of blood pressure and urine output (p < 0.001) without adverse effects.

CONCLUSIONS

Low-dose epinephrine infusion may be considered as an alternative treatment to standard starting doses in hypotensive neonatal intensive care unit patients.

Perioperative management of arteriovenous malformation guided by integrated evaluation of hemodynamics

We aimed to demonstrate the value of monitoring infants with arteriovenous malformation (AVM) during endovascular embolization with integrated evaluation of hemodynamics (IEH) and guiding decisions according to the underlying pathophysiology. This is a retrospective analysis of the perioperative hemodynamics data for 2 complex cases of AVM transferred to Khaula Hospital in Oman for interventional management. We described the value of novel physiological insights gained from comprehensive IEH and provided a systematic approach to the perioperative management. Postoperative targeted neonatal echo (TNE) was used to guide the weaning of the cardiovascular medications within 24 h. Both cases showed significant right ventricle (RV) volume overload before surgery. Narrowing of the pulse pressure (PP) during or after endovascular embolization was used as a marker of compromised systemic blood flow in real time followed by an assessment by TNE to guide the appropriate therapy.Conclusion: Integrated evaluation of hemodynamics is helpful to guide perioperative physiologic-based management of AVM. What is Known: • The preoperative management of hemodynamic compromise due to AVM has been described in many articles. • Perioperative management of AVM and related hemodynamics is a challenge to the intensive care team. What is New: • Integrated evaluation of hemodynamics is a comprehensive assessment and helpful in understanding the underlying physiologic changes during intervention with AVM. • This integrated evaluation can lead to physiologic-based medical recommendation with subsequent improvement.

Pharmacological Heart Failure Therapy in Children: Focus on Inotropic Support

Pediatric heart failure is a clinical syndrome, which needs to be distinctly defined and the pathophysiological consequences considered. Pharmacological treatment depends on the disease- and age-specific myocardial characteristics. Acute and chronic low cardiac output is the result of an inadequate heart rate (rhythm), myocardial contractility, preload and afterload, and also ventriculo-ventricular interaction, synchrony, atrio-ventricular and ventricular-arterial coupling. The treatment of choice is curing the cause of heart failure, if possible.Acute HF therapy is still based to the use of catecholamines and inodilators. The cornerstone of chronic HF treatment consists of blocking the endogenous, neuro-humoral axis, in particular the adrenergic and renin-angiotensin-aldosterone system.Before neprilysin inhibitors are used in young children, their potential side-effect for inducing Alzheimer disease needs to be clarified. The focus of the current review is put on the differential use of the inotropic drugs as epinephrine, norepinephrine, dopamine and dobutamine, and also the inodilators milrinone and levosimendan. Considering effects and side-effects of any cardiac stimulating treatment strategy, co-medication with ß-blockers, angiotensin converting inhibitors (ACEIs), angiotensin blockers (ARBs) and mineralocorticoid receptor antagonists (MRAs) is not a contradiction, but a senseful measure, even still during the acute inotropic treatment.Missing sophisticated clinical trials using accurate entry criteria and clinically relevant endpoints, there is especially in cardiovascular diagnosis and treatment of young children a compromise of evidence-based versus pathophysiology-based procedures. But based on the pharmacological and pathophysiological knowledge a hypothesis-driven individualized treatment is already currently possible and therefore indicated.

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.

Hypothermia and Cardiovascular Instability

Severely asphyxiated neonates have acute heart failure as part of their multiorgan dysfunction syndrome during the first days of life. Supporting the cardiovascular system during this phase is part of contemporary treatment and regarded as vital for limiting the neurodevelopmental injury. The decision to treat cardiovascular instability should be based on evaluation of end-organ function. Neonatologist-performed echocardiography in combination with other diagnostic modalities enables comprehensive real-time assessment. This review discusses associations between hemodynamics and adverse outcome, modalities for evaluating the hemodynamic state of the infant, and therapeutic approaches during intensive care.

Cardiopulmonary failure in children infected with Enterovirus A71

Enterovirus A71 (EV-A71) is one of the causative pathogens of hand, foot, and mouth disease (HFMD), which may cause severe neurological and cardiopulmonary complications in children. In this review, we discuss the pathogenesis, clinical manifestations, management strategy, and clinical outcomes of cardiopulmonary failure (CPF) in patients with EV-A71 infection.

The pathogenesis of CPF involves both catecholamine-related cardiotoxicity following brainstem encephalitis and vasodilatory shock due to cytokine storm. Sympathetic hyperactivity, including tachycardia and hypertension, are the early clinical manifestations of cardiopulmonary involvement, which may progress to pulmonary edema/hemorrhage and/or CPF. The management strategy comprises multidisciplinary supportive treatment, including fluid management, positive pressure ventilation support, and use of milrinone, vasopressors, and inotropes. Some patients may require extracorporeal membrane oxygenation. Major neurological sequelae are almost inevitable once a child develops life-threatening illness. Long-term care of these children is an important medico-social issue.

Population pharmacokinetics and pharmacodynamics of dobutamine in neonates on the first days of life

AIMS

To describe the pharmacokinetics (PK) and concentration-related effects of dobutamine in critically ill neonates in the first days of life, using nonlinear mixed effects modelling.

METHODS

Dosing, plasma concentration and haemodynamic monitoring data from a dose-escalation study were analysed with a simultaneous population PK and pharmacodynamic model. Neonates receiving continuous infusion of dobutamine 5-20 μg kg-1 min-1 were included. Left ventricular ejection fraction (LVEF) and cardiac output of right and left ventricle (RVO, LVO) were measured on echocardiography; heart rate (HR), mean arterial pressure (MAP), peripheral arterial oxygen saturation and cerebral regional oxygen saturation were recorded from patient monitors.

RESULTS

Twenty-eight neonates with median (range) gestational age of 30.4 (22.7-41.0) weeks and birth weight (BW) of 1618 (465-4380) g were included. PK data were adequately described by 1-compartmental linear structural model. Dobutamine clearance (CL) was described by allometric scaling on BW with sigmoidal maturation function of postmenstrual age (PMA). The final population PK model parameter mean typical value (standard error) estimates, standardised to median BW of 1618 g, were 41.2 (44.5) L h-1 for CL and 5.29 (0.821) L for volume of distribution, which shared a common between subject variability of 29% (17.2%). The relationship between dobutamine concentration and RVO/LVEF was described by linear model, between concentration and LVO/HR/MAP/cerebral fractional tissue oxygen extraction by sigmoidal Emax model.

CONCLUSION

In the postnatal transitional period, PK of dobutamine was described by a 1-compartmental linear model, CL related to BW and PMA. A concentration-response relationship with haemodynamic variables has been established.

The efficacy of dopamine versus epinephrine for pediatric or neonatal septic shock: a meta-analysis of randomized controlled studies

INTRODUCTION

The efficacy of dopamine versus epinephrine for pediatric or neonatal septic shock remains controversial. We conduct a meta-analysis to explore the influence of dopamine versus epinephrine on shock reversal for pediatric or neonatal septic shock.

METHODS

We have searched PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases through July 2019 for randomized controlled trials (RCTs) assessing the efficacy and safety of dopamine versus epinephrine for pediatric or neonatal septic shock.

RESULTS

Three RCTs are included in the meta-analysis. Overall for pediatric or neonatal septic shock, dopamine and epinephrine reveal comparable shock reversal within 1 h (risk ratios (RR) = 0.61; 95% CI = 0.16 to 2.31; P = 0.47), mortality (RR = 1.16; 95% CI = 0.87 to 1.55; P = 0.30), heart rate (standard mean differences (SMD) = 0.03; 95% CI = -0.28 to 0.34; P = 0.85), systolic blood pressure (SMD = -0.18; 95% CI = -0.69 to 0.33; P = 0.49), mean arterial pressure (SMD = -0.15; 95% CI = -1.64 to 1.34; P = 0.84) and adverse events (RR = 1.00; 95% CI = 0.94 to 1.07; P = 0.91).

CONCLUSIONS

Dopamine and epinephrine show the comparable efficacy for the treatment of pediatric or neonatal septic shock.

Association between dopamine and cerebral autoregulation in preterm neonates

BACKGROUND

To test the hypothesis that dopamine is associated with impaired cerebral autoregulation (ICA) in a dose-dependent fashion.

METHODS

Non a priori designed secondary analysis of a prospectively enrolled cohort study subjects <12 h of life between 24⁰ and 29⁶ weeks gestation. Cerebral saturations (rScO2) and mean arterial blood pressure (MAP) were continuously monitored every 30 s for 96 h. ICA was defined by a 10 min epoch rScO2-MAP correlation coefficient of >0.5.

RESULTS

Twenty-three of 61 subjects (38%) required dopamine. Time spent with ICA was 23% in dopamine-exposed subjects vs. 14% in those not exposed (p = 0.0001). On the epoch level, time spent with ICA was 15%, 29%, 34%, 37%, and 23% in epochs with dopamine titration of 0, 1-5, 6-10, 11-15, and 16-20 μg/kg/min, respectively. Using mixed-effect modeling, ICA for each dopamine titration was significantly higher than unexposed times when controlling for gestation, presence of a patent ductus arteriosus, day of life, MAP less than gestational age, and illness severity score (p < 0.02).

CONCLUSIONS

Dopamine exposure during the first 96 h was associated with ICA. Time periods with ICA increased with dopamine exposure in a dose-dependent fashion peaking at a concentration of 11-15 μg/kg/min.

Late-onset glucocorticoid-responsive circulatory collapse in premature infants

Late-onset glucocorticoid-responsive circulatory collapse (LGCC) in infants is characterized by sudden onset of hypotension and/or oliguria, which is resistant to volume expanders and inotropes but responds rapidly to intravenous glucocorticoids. LGCC occurs after the first week of life mainly in relatively stable very low birth weight (VLBW) infants. In Japan, the incidence of LGCC is reported to be 8%. Relative adrenal insufficiency (AI) is considered the most likely cause of LGCC, but its detailed pathophysiology remains unclear. Intrinsic and extrinsic factors may affect the pathophysiological mechanism. LGCC should be recognized as one of the high-risk complications in VLBW infants and managed promptly and properly, because if it is not, it may cause life-long neurological problems. To diagnose relative AI, an accurate evaluation of adrenal function is necessary; however, the interpretation of basal serum cortisol levels is difficult in preterm infants after 7 days of life. To recognize LGCC, it is recommended that blood pressure and urine volume be carefully monitored, even outside of the transitional period. If no underlying causes are documented or volume expansion and inotropic support fail, intravenous hydrocortisone should be initiated, and an additional dose of hydrocortisone is required when the response is inadequate. There are few reports to verify or characterize LGCC and this phenomenon has not been recognized worldwide to date. This review summarizes the current knowledge about LGCC in premature infants and evaluates the most significant new findings regarding its pathophysiology, treatment, and prognosis.

Cerebral autoregulation in premature infants during the first 96 hours of life and relationship to adverse outcomes

OBJECTIVE

To test the hypothesis that impaired cerebral autoregulation (ICA) increases the susceptibility of premature infants to adverse outcomes, we determined the relationship of ICA and cerebral reactivity (CR) measured in the first 96 hours of life to the outcome of grade 3 or 4 intraventricular haemorrhage (IVH) and/or death within 1 month.

SETTING

Single-centre level IV neonatal intensive care unit.

PATIENTS

Neonates 24-29 weeks' gestation less than 12 hours old with invasive blood pressure monitoring.

DESIGN

Cerebral saturations and mean arterial blood pressure were recorded every 30 s for 96 hours. For each 10 min epoch, the correlation coefficient (r) was calculated for mean arterial blood pressure versus cerebral saturations. The epoch was considered to have ICA if r>0.5 and CR if r<0.

RESULTS

Sixty-one subjects were included. During the first 96 hours, ICA occurred 17.6% and CR occurred 41% of recorded time. In those without adverse outcomes, ICA decreased and CR increased by postnatal day (p<0.05). Adjusted for birth weight and gestational age, those with IVH and those who died spent more time with ICA and less time with CR (p<0.05) over the entire recording period. Those with IVH had 1.5-fold increase in time with ICA on day 2 (p=0.021), and decrease in time with CR on day 3 (p=0.036). Compared with survivors, non-survivors spent more time with ICA on days 3 and 4 (p<0.005), and less with CR on day 3 (p=0.032).

CONCLUSION

ICA and CR vary by postnatal day and these patterns are associated with adverse outcomes.

Cardiopulmonary Bypass in Premature and Low Birth Weight Neonates - Implications for Postoperative Care From a Neonatologist/Intensivist Perspective

Prematurity and low weight remain significant risk factors for mortality after neonatal cardiac surgery despite steady gains in survival. Newer and lower weight thresholds for operability are constantly generated as surgeons gather proficiency, technical mastery, and experience in performing complex procedures on extremely small infants. Relationship between birth weight and survival after cardiac surgery is nonlinear with 2 kg being an inflection point below which marked decline in survival occurs. If strides toward improved survival in this weight category are to be made, understanding the inherent vulnerabilities of the premature and low birth weight infant is important in addition to acknowledging the vulnerabilities of the system in which care is delivered.

Early inotropes use is associated with higher risk of death and/or severe brain injury in extremely premature infants

Introduction: Extremely premature infants are susceptible to fluctuations in cerebral blood flow due to immaturity of cerebral autoregulation. Inotropes may cause rapid changes to systemic blood pressure and consequently cerebral blood flow, especially within the first 72 hours of life. This period is recognized to carry the greatest risk for cerebral hemorrhage. This study evaluates the incidence of death and/or severe brain injury in extremely preterm infants treated with inotropes in the first 72 hours of life.Methods: Prospective cohort study of infants born ≤29⁺⁰ weeks gestational age (GA) between January 2013 and December 2016. Severe brain injury was defined based on head ultrasound as presence of: grade III or IV intraventricular hemorrhage (IVH), moderate to severe post-hemorrhagic ventricular dilatation (PHVD), or cystic periventricular leukomalacia (cPVL). The association between inotrope use and death and/or brain injury was explored via logistic regression controlling for predefined confounding risk factors.Results: Of 497 eligible infants, 97 (19.5%) received inotropes during the first 72 hours. GA at birth, birth weight (BW), and 5-minute Apgar scores were lower among infants who received early inotropes compared to those not treated with inotropes. A stepwise logistic regression of the predefined confounding factors showed GA, exposure for antenatal steroids, and admission hypothermia to be significant confounding factors. Adjusting for those factors, early use of inotropes was associated with increased risk of death and/or severe brain injury (AOR 4.5; 95%CI: 2.4-8.5), severe brain injury (AOR 4.2; 95% CI: 1.9-8.9), and IVH of any grade (AOR 2.9; 95%CI: 1.7-4.9).Conclusion: Early inotropes use was associated with higher risk of death and/or severe brain injury. Strict indications and strategies for minimizing inotrope use while preventing hypotension should be implemented in the early postnatal care of infants at risk for severe brain injury.

Current Challenges in Neonatal Resuscitation: What is the Role of Adrenaline?

Adrenaline, also known as epinephrine, is a hormone, neurotransmitter, and medication. It is the best established drug in neonatal resuscitation, but only weak evidence supports current recommendations for its use. Furthermore, the available evidence is partly based on extrapolations from adult studies, and this introduces further uncertainty, especially when considering the unique physiological characteristics of newly born infants. The timing, dose, and route of administration of adrenaline are still debated, even though this medication has been used in neonatal resuscitation for a long time. According to the most recent Neonatal Resuscitation Guidelines from the American Heart Association, adrenaline use is indicated when the heart rate remains < 60 beats per minute despite the establishment of adequate ventilation with 100% oxygen and chest compressions. The aforementioned guidelines recommend intravenous administration (via an umbilical venous catheter) of adrenaline at a dose of 0.01-0.03 mg/kg (1:10,000 concentration). Endotracheal administration of a higher dose (0.05-0.1 mg/kg) may be considered while venous access is being obtained, even if supportive data for endotracheal adrenaline are lacking. The safety and efficacy of intraosseous administration of adrenaline remain to be investigated. This article reviews the evidence on the circulatory effects and tolerability of adrenaline in the newborn, discusses literature data on adrenaline use in neonatal cardiopulmonary resuscitation, and describes international recommendations and outcome data regarding the use of this medication during neonatal resuscitation.

Epinephrine versus dopamine in neonatal septic shock: a double-blind randomized controlled trial

We compared epinephrine and dopamine as a first-line vasoactive drug in 40 neonates (enrolled in two gestational age strata ≤ 30^6/7 and ≥ 31^0/7 weeks) with fluid-refractory septic shock. Epinephrine or dopamine was initiated at 0.2 or 10 μg/kg/min, respectively. If shock persisted after 15 min, epinephrine or dopamine was increased to 0.3 or 15 μg/kg/min, respectively (16-30 min), and thereafter to 0.4 or 20 μg/kg/min (31-45 min). Proportion of neonates achieving 'reversal of shock' (defined as systolic and diastolic BP > fifth centile and capillary filling time < 3 s and left ventricular output ≥ 150 mL/kg/min) by 45 min [5 (25%) vs 6 (30%), RR 0.83 (95% CI 0.30, 2.29)]; haemodynamic stability (shock reversal for ≥ 120 min without escalation of vasoactive drugs) anytime during therapy [10 (50%) vs 6 (30%), RR 1.67 (95% CI 0.75, 3.71)]; and all-cause mortality by 28 days [14 (70%) vs 16 (80%), RR 0.87 (95% CI 0.61, 1.26)] were comparable in the epinephrine and dopamine groups, respectively. On stratified analysis, we observed an interaction of gestational age strata with the group of allocation favouring epinephrine in neonates ≤ 30^6/7 weeks.Conclusion: Epinephrine (0.2-0.4 μg/kg/min) and dopamine (10-20 μg/kg/min) had comparable efficacy and safety in neonatal septic shock.Clinical Trial registry name and registration number: The study was registered with Clinical Trial Registry of India CTRI/2015/10/006285. What is Known: • The choice of vasoactive drugs in neonatal septic shock is empirical and dopamine is the conventional first-line vasoactive drug. • There are no randomized controlled trials comparing dopamine and epinephrine in neonatal septic shock. What is New: • In this study, epinephrine and dopamine had comparable efficacy and safety as a first-line vasoactive drug in management of neonatal septic shock. • On stratified analysis in a limited sample, epinephrine was associated with better outcomes in neonates ≤ 30^6/7 weeks.

Dobutamine treatment reduces inflammation in the preterm fetal sheep brain exposed to acute hypoxia

BACKGROUND

Impaired cerebral autoregulation in preterm infants makes circulatory management important to avoid cerebral hypoxic-ischemic injury. Dobutamine is frequently used as inotropic treatment in preterm neonates, but its effects on the brain exposed to cerebral hypoxia are unknown. We hypothesized that dobutamine would protect the immature brain from cerebral hypoxic injury.

METHODS

In preterm (0.6 gestation) fetal sheep, dobutamine (Dob, 10 μg/kg/min) or saline (Sal) was infused intravenously for 74 h. Two hours after the beginning of the infusion, umbilical cord occlusion (UCO) was performed to produce fetal asphyxia (Sal+UCO: n = 9, Dob+UCO: n = 7), or sham occlusion (Sal+sham: n = 7, Dob+sham: n = 6) was performed. Brains were collected 72 h later for neuropathology.

RESULTS

Dobutamine did not induce cerebral changes in the sham UCO group. UCO increased apoptosis and microglia density in white matter, hippocampus, and caudate nucleus, and astrocyte density in the caudate nucleus. Dobutamine commenced before UCO reduced microglia infiltration in the white matter, and microglial and astrocyte density in the caudate.

CONCLUSION

In preterm hypoxia-induced brain injury, dobutamine decreases neuroinflammation in the white matter and caudate, and reduces astrogliosis in the caudate. Early administration of dobutamine in preterm infants for cardiovascular stabilization appears safe and may be neuroprotective against unforeseeable cerebral hypoxic injury.

Effects of hypoxia-ischemia and inotropes on expression of cardiac adrenoceptors in the preterm fetal sheep

Preterm infants frequently suffer cardiovascular compromise, with hypotension and/or low systemic blood flow, leading to tissue hypoxia-ischemia (HI). Many preterm infants respond inadequately to inotropic treatments using adrenergic agonists such as dobutamine (DB) or dopamine (DA). This may be because of altered cardiac adrenoceptor expression because of tissue HI or prolonged exposure to adrenergic agonists. We assessed the effects of severe HI with and without DB/DA treatment on cardiac adrenoceptor expression in preterm fetal sheep. Fetal sheep (93-95 days) exposed to sham surgery or severe HI induced by umbilical cord occlusion received intravenous DB or saline for 74 h (HI + DB, HI, Sham + DB, Sham). The HI groups were also compared with fetal sheep exposed to HI and DA. Fetal hearts were collected to determine β-adrenoceptor numbers using [¹²⁵I]-cyanopindolol binding and mRNA expression of β₁-, β₂-, α_1A-, α_2A-, or α_2B-adrenoceptors. The HI group had increased β-adrenoceptor numbers compared with all other groups in all four heart chambers ( P < 0.05). This increase in β-adrenoceptor numbers in the HI group was significantly reduced by DB infusion in all four heart chambers, but DA infusion in the HI group only reduced β-adrenoceptor numbers in the left atria and ventricle. DB alone did not affect β-adrenoceptor numbers in the sham animals. Changes in β₁-adrenoceptor mRNA levels trended to parallel the binding results. We conclude that HI upregulates preterm fetal cardiac β-adrenoceptors, but prolonged exposure to adrenergic agonists downregulates adrenoceptors in the preterm heart exposed to HI and may underpin the frequent failure of inotropic therapy in preterm infants. NEW & NOTEWORTHY This is the first study, to our knowledge, on the effects of hypoxia-ischemia and adrenergic agonists on adrenoceptors in the preterm heart. In fetal sheep, we demonstrate that hypoxia-ischemia increases cardiac β-adrenoceptor numbers. However, exposure to both hypoxia-ischemia and adrenergic agonists (dobutamine or dopamine) reduces the increase in β-adrenoceptor numbers, which may underpin the inadequate response in human preterm infants to inotropic therapy using adrenergic agonists. Dobutamine alone does not affect the cardiac adrenoceptors in the sham animals.

Dopamine plasma clearance is increased in piglets compared to neonates during continuous dopamine infusion

AIM

Piglets models have often been used to study the effects of dopamine infusion on hypotension in neonates. However, piglets need higher doses of dopamine than neonates to increase blood pressure. We investigated whether this difference was due to interspecific difference in dopamine pharmacokinetics.

METHODS

Arterial blood samples were drawn from six neonates admitted to the neonatal intensive care unit of Copenhagen University Hospital and 20 newborn piglets during continuous dopamine infusion. Furthermore, to estimate the piglet plasma dopamine half-life, blood samples were drawn at 2.5-minute intervals after the dopamine infusion was discontinued. The plasma dopamine content was analysed by high-performance liquid chromatography with electrochemical detection.

RESULTS

The dopamine displayed first-order kinetics in piglets and had a half-life of 2.5 minutes, while the median plasma clearance was 627.9 mL/kg/minute (interquartile range 452.6-1914.4). Both piglets and neonates showed large interindividual variations in plasma clearance, but the median tended to be lower in neonates (384.9, interquartile range 114.2-480.2 mL/kg/minute).

CONCLUSION

Our results suggest that pharmacokinetic differences may explain the interspecific difference in required doses of dopamine infusion to increase blood pressure. This is important when translating the results obtained in piglet models to treating neonatal hypotension with dopamine.

Treating Hypotension in Preterm Neonates With Vasoactive Medications

Preterm neonates often have hypotension which may be due to various etiologies. While it is controversial to define hypotension in preterm neonates, various vasoactive medications are commonly used to provide the cardiovascular support to improve the blood pressure, cardiac output, or to treat shock. However, the literature on the systemic and regional hemodynamic effects of these antihypotensive medications in neonates is deficient and incomplete, and cautious translation of findings from other clinical populations and animal studies is required. Based on a literature search on published reports, meta-analytic reviews, and selected abstracts, this review discusses the current available information on pharmacologic actions, clinical effects, and side effects of commonly used antihypotensive medications including dopamine, dobutamine, epinephrine, norepinephrine, vasopressin, and milrinone in preterm neonates.

Inotropes for Preterm Infants: 50 Years on Are We Any Wiser?

For almost half a century, inotropes have been administered to preterm infants with the ultimate goal of increasing their blood pressure. A number of trials, the majority of which focused on dopamine administration, have demonstrated increased blood pressure following inotrope administration in preterm infants and have led to continued use of inotropes in our neonatal units. We have also seen an increase in the number of potential agents available to the clinician. However, we now know that hypotension is a much broader concept than blood pressure alone, and our aim should instead be focused on improving end organ perfusion, specifically cerebral perfusion. Only a limited number of studies have incorporated the organ-relevant hemodynamic changes and long-term outcomes when assessing inotropic effects in neonates, the majority of which are observational studies or have a small sample size. In addition, important considerations, including the developing/maturing adrenergic receptors, polymorphisms of these receptors, and other differences in the pharmacokinetics and pharmacodynamics of preterm infants, are only recently being recognized. Certainly, there remains huge variation in practice. The lack of well-conducted randomized controlled trials addressing these relevant outcomes, along with the difficulty executing such RCTs, leaves us with more questions than answers. This review provides an overview of the various inotropic agents currently being used in the care of preterm infants, with a particular focus on their organ/cerebral hemodynamic effects both during and after transition.

The role of Neonatologist Performed Echocardiography in the assessment and management of neonatal shock

One of the major challenges of neonatal intensive care is the early detection and management of circulatory failure. Routine clinical assessment of the hemodynamic status of newborn infants is subjective and inaccurate, emphasizing the need for objective monitoring tools. An overview will be provided about the use of neonatologist-performed echocardiography (NPE) to assess cardiovascular compromise and guide hemodynamic management. Different techniques of central blood flow measurement, such as left and right ventricular output, superior vena cava flow, and descending aortic flow are reviewed focusing on methodology, validation, and available reference values. Recommendations are provided for individualized hemodynamic management guided by NPE.

Cardiovascular Supportive Therapies for Neonates With Asphyxia - A Literature Review of Pre-clinical and Clinical Studies

Asphyxiated neonates often have hypotension, shock, and poor tissue perfusion. Various "inotropic" medications are used to provide cardiovascular support to improve the blood pressure and to treat shock. However, there is incomplete literature on the examination of hemodynamic effects of these medications in asphyxiated neonates, especially in the realm of clinical studies (mostly in late preterm or term populations). Although the extrapolation of findings from animal studies and other clinical populations such as children and adults require caution, it seems appropriate that findings from carefully conducted pre-clinical studies are important in answering some of the fundamental knowledge gaps. Based on a literature search, this review discusses the current available information, from both clinical studies and animal models of neonatal asphyxia, on common medications used to provide hemodynamic support including dopamine, dobutamine, epinephrine, milrinone, norepinephrine, vasopressin, levosimendan, and hydrocortisone.

Low-frequency blood pressure oscillations and inotrope treatment failure in premature infants

The underlying mechanism as to why some hypotensive preterm infants do not respond to inotropic medications remains unclear. For these infants, we hypothesize that impaired vasomotor function is a significant factor and is manifested through a decrease in low-frequency blood pressure variability across regulatory components of vascular tone. Infants born ≤28 wk estimated gestational age underwent prospective recording of mean arterial blood pressure for 72 h after birth. After error correction, root-mean-square spectral power was calculated for each valid 10-min data frame across each of four frequency bands (B1, 0.005-0.0095 Hz; B2, 0.0095-0.02 Hz; B3, 0.02-0.06 Hz; and B4, 0.06-0.16) corresponding to different components of vasomotion control. Forty infants (twenty-nine normotensive control and eleven inotrope-exposed) were included with a mean ± SD estimated gestational age of 25.2 ± 1.6 wk and birth weight 790 ± 211 g. 9.7/11.8 Million (82%) data points were error-free and used for analysis. Spectral power across all frequency bands increased with time, although the magnitude was 20% less in the inotrope-exposed infants. A statistically significant increase in spectral power in response to inotrope initiation was noted across all frequency bands. Infants with robust blood pressure response to inotropes had a greater increase compared with those who had limited or no blood pressure response. In this study, hypotensive infants who require inotropes have decreased low-frequency variability at baseline compared with normotensive infants, which increases after inotrope initiation. Low-frequency spectral power does not change for those with inotrope treatment failure, suggesting dysfunctional regulation of vascular tone as a potential mechanism of treatment failure.NEW & NOTEWORTHY In this study, we examine patterns of low-frequency oscillations in blood pressure variability across regulatory components of vascular tone in normotensive and hypotensive infants exposed to inotropic medications. We found that hypotensive infants who require inotropes have decreased low-frequency variability at baseline, which increases after inotrope initiation. Low-frequency spectral power does not change for those with inotrope treatment failure, suggesting dysfunctional regulation of vascular tone as a potential mechanism of treatment failure.

[Vasopressors and inotropes: use in paediatrics]

The cardiovascular system is a dynamic system, which is required to ensure adequate delivery of oxygen, nutrients, and hormones to the tissues that are necessary for cell metabolism. It also synthesises and modifies the vasoactive components that regulate vascular tone and myocardial function. These vasoactive components have demonstrated their beneficial effects in the management of paediatric patients in a critical condition with heart failure and shock. However, their use and abuse brings harmful effects, increases mortality, and is associated with arrhythmias. An increase in myocardial oxygen consumption favours the presence of ischaemia, therefore it is necessary to know the mechanism of action and indications of these drugs to minimise their harmful effects. The purpose of this review is to describe the pharmacology and clinical applications of inotropic and vasopressor agents in the paediatric patient in acritical condition.

Congenital Diaphragmatic hernia - a review

Congenital Diaphragmatic hernia (CDH) is a condition characterized by a defect in the diaphragm leading to protrusion of abdominal contents into the thoracic cavity interfering with normal development of the lungs. The defect may range from a small aperture in the posterior muscle rim to complete absence of diaphragm.

The pathophysiology of CDH is a combination of lung hypoplasia and immaturity associated with persistent pulmonary hypertension of newborn (PPHN) and cardiac dysfunction. Prenatal assessment of lung to head ratio (LHR) and position of the liver by ultrasound are used to diagnose and predict outcomes. Delivery of infants with CDH is recommended close to term gestation. Immediate management at birth includes bowel decompression, avoidance of mask ventilation and endotracheal tube placement if required. The main focus of management includes gentle ventilation, hemodynamic monitoring and treatment of pulmonary hypertension followed by surgery. Although inhaled nitric oxide is not approved by FDA for the treatment of PPHN induced by CDH, it is commonly used.

Extracorporeal membrane oxygenation (ECMO) is typically considered after failure of conventional medical management for infants ≥ 34 weeks’ gestation or with weight >2 kg with CDH and no associated major lethal anomalies. Multiple factors such as prematurity, associated abnormalities, severity of PPHN, type of repair and need for ECMO can affect the survival of an infant with CDH. With advances in the management of CDH, the overall survival has improved and has been reported to be 70-90% in non-ECMO infants and up to 50% in infants who undergo ECMO.

Hemodynamic and metabolic effects of a new pediatric dobutamine formulation in hypoxic newborn pigs

BACKGROUND

The aim of our study was to measure drug-related changes in hemodynamics and oxygen metabolism in response to different doses of an age-appropriate dobutamine formulation in hypoxic pigs. A secondary aim was to validate superior vena cava flow (SVCF) as a marker of cardiac index (CI) for subsequent clinical trials of this formulation in humans.

METHODS

Newborn pigs (n = 18) were exposed to 2-h hypoxia (10-15% oxygen) followed by reoxygenation (21-30% oxygen 4 h). After 1-h reoxygenation, pigs were randomized to: control group (no treatment), dobutamine infusion at a rate of 10-15 or 15-20 µg/kg/min. Dobutamine groups received two dobutamine doses during 30 min with a 60 min washout period between doses. Cardiovascular profile and oxygen metabolism were monitored. In four animals, an ultrasonic perivascular flow probe was placed around superior vena cava to measure SVCF.

RESULTS

Hypoxia significantly decreased CI, systemic vascular resistance and mean arterial blood pressure (MABP). Dobutamine doses significantly increased heart-rate, CI, and oxygen-delivery without changes in stroke-volume and MABP. Only 10-15 µg/kg/min increased oxygen consumption and peripheral tissue oxygenation measured by Near-infrared spectroscopy. A positive correlation was observed between SVCF and CI.

CONCLUSION

The new pediatric dobutamine formulation improved hemodynamic status, with dose-specific differences in metabolic response. SVCF may be a useful surrogate for CI in subsequent clinical trials.

Quantifying cerebral hypoxia by near-infrared spectroscopy tissue oximetry: the role of arterial-to-venous blood volume ratio

Tissue oxygenation estimated by near-infrared spectroscopy (NIRS) is a volume-weighted mean of the arterial and venous hemoglobin oxygenation. In vivo validation assumes a fixed arterial-to-venous volume-ratio (AV-ratio). Regulatory cerebro-vascular mechanisms may change the AV-ratio. We used hypotension to investigate the influence of blood volume distribution on cerebral NIRS in a newborn piglet model. Hypotension was induced gradually by inflating a balloon-catheter in the inferior vena cava and the regional tissue oxygenation from NIRS ( rStO 2 , NIRS ) was then compared to a reference ( rStO 2 , COX ) calculated from superior sagittal sinus and aortic blood sample co-oximetry with a fixed AV-ratio. Apparent changes in the AV-ratio and cerebral blood volume (CBV) were also calculated. The mean arterial blood pressure (MABP) range was 14 to 82 mmHg. PaCO 2 and SaO 2 were stable during measurements. rStO 2 , NIRS mirrored only 25% (95% Cl: 21% to 28%, p < 0.001 ) of changes in rStO 2 , COX . Calculated AV-ratio increased with decreasing MABP (slope: ? 0.007 · mmHg ? 1

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.