Cardiovascular, renal, and endocrine actions of dopamine in neonates and children

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.

The Use of Low-Dose Dopamine in the Neonatal Intensive Care Unit

Dopamine has been used for half a century in adult and pediatric patients for the treatment of hypotension, as well as for the theoretical prevention of acute kidney injury (AKI). Although activation of renal dopamine receptors leads to increased urine output, there is no evidence that low-dose dopamine reduces the incidence of AKI, need for dialysis, or death. Dopamine administration is also associated with multiple adverse effects, particularly in preterm infants. Despite the lack of evidence for its use, as well as the known adverse effects of dopamine, many neonatologists still use low-dose dopamine to prevent or treat AKI in neonates. In this review, we provide a summary of our current medical knowledge about the use of low-dose dopamine in the neonatal population.

The Use of Low-Dose Dopamine in the Neonatal Intensive Care Unit

Dopamine has been used for half a century in adult and pediatric patients for the treatment of hypotension, as well as for the theoretical prevention of acute kidney injury (AKI). Although activation of renal dopamine receptors leads to increased urine output, there is no evidence that low-dose dopamine reduces the incidence of AKI, need for dialysis, or death. Dopamine administration is also associated with multiple adverse effects, particularly in preterm infants. Despite the lack of evidence for its use, as well as the known adverse effects of dopamine, many neonatologists still use low-dose dopamine to prevent or treat AKI in neonates. In this review, we provide a summary of our current medical knowledge about the use of low-dose dopamine in the neonatal population.

Use of norepinephrine in preterm neonates with dopamine-resistant shock: a retrospective single-centre cross-sectional study

BACKGROUND

Norepinephrine (NE) is recommended for children and full-term neonates (born at >37 gestational weeks) with septic shock. Meanwhile, data on the effectiveness of NE in preterm neonates are still limited. This study aimed to evaluate the clinical efficacy of NE in preterm neonates with dopamine-resistant shock compared with that in full-term neonates.

METHODS

This was a single-centre, retrospective (January 2010-December 2020) cohort study of neonates with persistent shock despite adequate fluid resuscitation and dopamine or dobutamine administration at ≥10 μg/kg/min. Medical records of neonates treated with NE were retrospectively reviewed to collect respiratory and haemodynamic parameters and results of arterial blood gas (ABG) tests before and 8 hours after NE infusion. The effectiveness of NE was assessed using changes in clinical parameters and multiple regression models for mortality among subgroups of preterm and full-term neonates.

RESULTS

Ninety-two neonates (76% preterm) who received NE infusion were included in the study. NE infusion was started after a median of 7 hours (IQR 2-19 hours) after shock onset. Among the preterm neonates, the maximum dose of NE infusion was 0.5 (IQR 0.3-1.0) µg/kg/min with a median duration of 45 (IQR 24.0-84.5) hours. Haemodynamic dysfunction was ameliorated with increased blood pressure, decreased heart rate and improved ABG results. Preterm neonates with septic shock tended to have a reduced response to NE; however, preterm neonates with persistent pulmonary hypertension of the newborn tended to have a better response. Thirty-four (37%) neonates died in our cohort. The timing, dose and duration of NE use were not associated with neonatal mortality.

CONCLUSIONS

Although using NE effectively improves clinical parameters in preterm neonates with dopamine-resistant shock, our study is underpowered to identify the association between NE infusion and mortality in preterm neonates with dopamine-resistant shock.

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.

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.

Preoperative Management of Neonates With Congenital Heart Disease

Clinicians caring for neonates with congenital heart disease encounter challenges in clinical care as these infants await surgery or are evaluated for further potential interventions. The newborn with heart disease can present with significant pathophysiologic heterogeneity and therefore requires a personalized therapeutic management plan. However, this complex field of neonatal-cardiac hemodynamics can be simplified. We explore some of these clinical quandaries and include specific sections reviewing the anatomic challenges in these patients. We propose this to serve as a primer focusing on the hemodynamics and therapeutic strategies for the preoperative neonate with systolic dysfunction, diastolic dysfunction, excessive pulmonary blood flow, obstructed pulmonary blood flow, obstructed systemic blood flow, transposition physiology, and single ventricle physiology.

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.

Concurrent and Selective Determination of Dopamine and Serotonin with Flexible WS2 /Graphene/Polyimide Electrode Using Cold Plasma

Makers of point-of-care devices and wearable diagnostics prefer flexible electrodes over conventional electrodes. In this study, a flexible electrode platform is introduced with a WS₂ /graphene heterostructure on polyimide (WGP) for the concurrent and selective determination of dopamine and serotonin. The WGP is fabricated directly via plasma-enhanced chemical vapor deposition (PECVD) at 150 °C on a flexible polyimide substrate. Owing to the limitations of existing fabrication methods from physical transfer or hydrothermal methods, many studies are not conducted despite excellent graphene-based heterostructures. The PECVD synthesis method can provide an innovative WS₂ /graphene heterostructure of uniform quality and sufficient size (4 in.). This unique heterostructure affords excellent electrical conductivity in graphene and numerous electrochemically active sites in WS₂ . A large number of uniform qualities of WGP electrodes show reproducible and highly sensitive electrochemical results. The synergistic effect enabled well-separated voltammetric signals for dopamine and serotonin with a potential gap of 188 mV. Moreover, the practical application of the flexible sensor is successfully evaluated by using artificial cerebrospinal fluid.

Hemodynamic optimization for neonates with neonatal encephalopathy caused by a hypoxic ischemic event: Physiological and therapeutic considerations

Neonatal encephalopathy due to a hypoxic-ischemic event is commonly associated with cardiac dysfunction and acute pulmonary hypertension; both therapeutic hypothermia and rewarming modify loading conditions and blood flow. The pathophysiological contributors to disease are complex with a high degree of clinical overlap and traditional bedside measures used to assess circulatory adequacy have multiple confounders. Comprehensive, quantitative echocardiography may be used to delineate the relative contribution of lung parenchymal, pulmonary vascular, and cardiac disease to hypotension and/or hypoxemic respiratory failure. In this review, we provide a detailed overview of the contributors to hemodynamic instability following perinatal hypoxic-ischemic injury. Our proposed approach to therapy focuses on physiopathological considerations with interventions individualized to this potentially complex condition and considers the pharmacological idiosyncrasies, which may occur among neonates with NE presenting with multiorgan dysfunction while undergoing therapeutic hypothermia.

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.

Renal aspects of metabolic acid-base disorders in neonates

Acid-base homeostasis is one of the most tightly regulated systems in the body. Maintaining the acid-base balance is particularly challenging for preterm infants and growing neonates. The kidney, which represents the crucial ultimate line of defense against disturbances of acid-base balance, undergoes a complex maturation process during the transition from a fetal to an extra-uterine environment. This review article summarizes the physiology of acid-base regulation by the immature human kidney and discusses disorders of acid-base balance, such as metabolic acidosis, respiratory acidosis, metabolic alkalosis, and respiratory alkalosis. In conditions of metabolic acidosis, the serum anion gap and the urinary anion gap can be useful tools to define the nature of the acidosis. Metabolic acidosis can reflect a decrease in glomerular filtration rate, or be the consequence of selective disorders of proximal or distal tubular function. Most tubulopathies associated with metabolic acidosis observed in neonates are primary, hereditary, isolated tubulopathies. Proximal renal tubular acidosis is characterized by bicarbonate wasting, while the distal types of renal tubular acidosis are secondary to distal acidification defects. All tubulopathies are associated with hypokalemia, with the exception of type 4 hyperkalemic distal renal tubular acidosis. The transporter defects in the various acid-base tubulopathies are now well defined. Treatment of the acidosis varies according to the site and mechanism of the defect. Chronic renal tubular acidosis or alkalosis severely impair growth and calcium metabolism. Early rational therapeutic intervention can prevent some of the consequences of the disorders and improves the prognosis.

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.

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.

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.

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.

Circulatory Insufficiency and Hypotension Related to the Ductus Arteriosus in Neonates

The biological role of the ductus arteriosus (DA) in neonates varies from an innocent bystander role during normal postnatal transition, to a supportive role when there is compromise to either systemic or pulmonary blood flow, to a pathological state in the presence of hemodynamically significant systemic to pulmonary shunts, as occurs in low birth weight infants. Among a wide array of clinical manifestations arising due to the ductal entity, systemic circulatory insufficiency and hypotension are of significant concern as they are particularly challenging to manage. An understanding of the physiologic interplay between the DA and the circulatory system is the key to developing appropriate targeted therapeutic strategies. In this review, we discuss the relationship of systemic hypotension to the DA, emphasizing the importance of critical thinking and a precise individual approach to intensive care support. We particularly focus on the variable states of hypotension arising directly due to a hemodynamically significant DA or seen in the period following successful surgical ligation. In addition, we explore the mechanistic contributions of the ductus to circulatory insufficiency that may manifest during the transitional period, states of maladapted transition (such as acute pulmonary hypertension of the newborn), and congenital heart disease (both ductal dependent and non-ductal dependent lesions). Understanding the dynamic modulator role of the ductus according to the ambient physiology enables a more precise approach to management. We review the pathophysiology, clinical manifestations, diagnosis, monitoring, and therapeutic intervention for the spectrum of DA-related circulatory compromise.

Timing of sepsis is an important risk factor for white matter abnormality in extremely premature infants with sepsis

BACKGROUND

Systemic infection is a major upstream mechanism for white matter abnormality (WMA). Our aim was to evaluate the risk factors for moderate-to-severe WMA in extremely premature infants (gestational age < 28 weeks) with neonatal sepsis.

METHODS

Extremely premature infants with culture-proven sepsis between 2006 and 2015 in a tertiary neonatal intensive care unit were classified as having none-to-mild or moderate-to-severe WMA based on WM scores of brain magnetic resonance imaging at the term-equivalent age. Various risk factors for WMA were analyzed.

RESULTS

Sixty-three infants (87.5%) had none-to-mild WMA, and nine infants (12.5%) had moderate-to-severe WMA. Multivariate logistic regression analysis revealed that postmenstrual age (PMA) at sepsis diagnosis (OR: 0.640, 95% CI: 0.435-0.941, p = 0.023) and PMA at sepsis diagnosis <28 weeks (OR: 9.232, 95% CI: 1.020-83.590, p = 0.048) were independently associated with moderate-to-severe WMA. PMA at sepsis diagnosis had a significant negative correlation with WM scores (r = -0.243, p = 0.039).

CONCLUSION

PMA at sepsis diagnosis might be an important risk factor for moderate-to-severe WMA in extremely premature infants with postnatal sepsis, especially before PMA 28 weeks. Infants who suffer from sepsis before PMA 28 weeks might need additional therapy for neuroprotection.

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.

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.

Mechanical and vasomotor properties of piglet isolated middle cerebral artery

Piglets are often used as experimental models for studying cerebrovascular responses in newborn infants. However, the mechanical characteristics of piglets’ middle cerebral arteries (MCA) are not well characterized. Additionally, the vessels’ response to dopamine, the most commonly used vasopressor in newborns, is not characterized in piglets’ MCA. Finally, the influence of preterm birth on the dopamine response is not known. The aim of this current was to compare by wire myography the active and passive mechanical characteristics and dopamine concentration–response relations of MCAs isolated from preterm and term newborn piglets. Second‐order branches of the MCA with a diameter <400 μm were chosen for study. The active and passive mechanical properties were comparable between vessels from six preterm (90% gestation, n_segments = 11) and nine term (n_segments = 22) newborn piglets. The response to increasing concentrations of dopamine was biphasic, starting with vasodilation in the 1 nmol/L–0.3 μmol/L concentration range followed by vasoconstriction at higher concentrations. The response was very similar between the two groups. In conclusion, the mechanical properties of the MCA as well as the response to dopamine were comparable between term and 90% gestation preterm piglets.

Pharmacological management of acute kidney injury and chronic kidney disease in neonates

Both acute kidney injury (AKI) and chronic kidney disease (CKD) are seen more frequently in the neonatal intensive care unit (NICU) as advances in supportive care improve the survival of critically ill infants as well as those with severe, congenital kidney and urinary tract anomalies. Many aspects of the infant's care, including fluid balance, electrolyte and mineral homeostasis, acid-base balance, and growth and nutrition require close monitoring by and collaboration among neonatologists, nephrologists, dieticians, and pharmacologists. This educational review summarizes the therapies widely used for neonates with AKI and CKD. Use of these therapies is extrapolated from data in older children and adults or based on clinical experience and case series. There is a critical need for more research on the use of therapies in infants with kidney disease as well as for the development of drug delivery systems and preparations scaled more appropriately for these small patients.

Renal adaptive changes and sodium handling in the fetal-to-newborn transition

Appropriate fluid and electrolyte management is critical for optimal care of very low birth weight or sick infants. Delivery of such care requires an understanding of developmental changes in renal water and salt handling that occur with advancing gestational age as well as postnatal age. This review focuses on the principles of sodium homeostasis during fetal and postnatal life. The physiology of renal tubular transport mechanisms, as well as neurohumoral factors impacting renal tubular transport are highlighted. Clinical implications and guidelines to the provision of sodium to this vulnerable population are also discussed.

Acute Renal Failure in the Neonate

Acute renal failure (ARF) is a common disorder in high-risk neonates. ARF may be oliguric or nonoliguric, the latter having a better prognosis. Risk factors for ARF include prematurity, respiratory and vascular disorders, heart failure, congenital uropathies, and the use of nephrotoxic drugs. Chemical analysis of urine and ultrasounds help differentiate the nature and the type of ARF: prerenal, intrinsic, or postrenal. Conservative management of prerenal forms of ARF consists in carefully restoring cardiac output and controlling fluid and electrolyte balances. Early relief of obstruction is mandatory in severe postrenal forms of ARF. Renal replacement therapy is often necessary when ARF is secondary to intrinsic renal damage: peritoneal dialysis is the treatment of choice. Hemodialysis and continuous venovenous hemofiltration may be used in specific cases. Overall prognosis of ARF depends on the nature and severity of the renal injury that has led to renal failure.

Response to dopamine in prematurity: a biomarker for brain injury?

OBJECTIVE

To identify factors associated with responsiveness to dopamine therapy for hypotension and the relationship to brain injury in a cohort of preterm infants.

STUDY DESIGN

The pharmacy database at St Louis Children's Hospital was retrospectively queried to identify infants who (a) were born <28 weeks gestation between 2012 and 2014, (b) received dopamine and (c) had blood pressure measurements from an umbilical arterial catheter. A control group was constructed from contemporaneous infants who did not receive dopamine. Mean arterial blood pressure (MABP) at baseline, 1 h and 3 h after initiating dopamine were obtained for each dopamine-exposed infant. MABP measurements at matched time points were obtained in the control group.

RESULT

Sixty-nine dopamine-treated and 45 control infants were included. Mean ΔMABP at 3 h was 4.5±6.3 mm of Hg for treated infants vs 1±2.9 for the control. Median dopamine starting dose was 2.5 μg kg(-1) min(-1). Dopamine-treated infants were less mature and of lower birth weight while also more likely to be intubated at 72 h, diagnosed with intraventricular hemorrhage (IVH) and to die. Failure to respond to dopamine was associated with greater likelihood of developing IVH (odds ratio (OR) 5.8, 95% confidence interval (CI) 1.1-42.3), while a strong response (ΔMABP>10 mm Hg) was associated with a reduction in risk of IVH (OR 0.1, 95% CI 0.01-0.8).

CONCLUSION

Low-moderate dose dopamine administration results in modest blood pressure improvements. A lack of response to dopamine is associated with a greater risk of IVH, whereas a strong response is associated with a decreased risk. Further research into underlying mechanisms and management strategies is needed.

Should dopamine be the first line inotrope in the treatment of neonatal hypotension? Review of the evidence

AIM: To determine if dopamine is effective in treating neonatal hypotension and safe to use comparing to other inotropes.

METHODS: This is a review of evidence on inotropic treatment of neonatal hypotension. Databases searched were MEDLINE and the Cochrane Library, a total of 134 studies were identified. Only studies with high quality evidence (level 1a and b and 2a) were included. After review, only eight studies were included in the final analysis. Pooled risk ratios derived for each outcome [Mantel-Haenzel (M-H) fixed effect] with CI, as reported in the Cochrane reviews were plotted in forest plot form.

RESULTS: Eight articles met inclusion criteria, which all included treatment in preterm infants. Dopamine increased mean arterial blood pressure (BP) (n = 163; r = 0.88, 95%CI: 0.76 to 0.94) and systolic BP (n = 142; r = 0.81, 95%CI: 0.42 to 0.94) comparing to placebo. Dopamine has been shown overall to be statistically more effective in increasing BP than dobutamine (n = 251, r = 0.26, 95%CI: 0.20-0.32). However there were no differences in short term outcomes (periventricular leucomalacia, periventricular haemorrhage) and mortality between both drugs. There is no statistical evidence of dopamine being more effective than adrenaline or corticosteroids. There was no difference in morbidity and mortality outcomes when dopamine was compared to hydrocortisone (RR 1.81, 95%CI: 0.18 to 18.39) or adrenaline.

CONCLUSION: In preterms, dopamine is the most studied drug, and we suggest it could be used as first line treatment in hypotension.

Undiagnosed congenital hypothyroidism in a newborn treated with dopamine infusion

Medications administered during the neonatal period may mask the diagnosis of congenital hypothyroidism. Herein, we report a case of undiagnosed congenital hypothyroidism while the infant was on treatment with dopamine. Given the inhibitory effect of dopamine on thyroid-stimulating hormone, a high index of suspicion for potential congenital hypothyroidism is needed in such neonates.

Vasopressin versus dopamine for treatment of hypotension in extremely low birth weight infants: a randomized, blinded pilot study

OBJECTIVE

To evaluate vasopressin vs dopamine as initial therapy in extremely low birth weight (ELBW) infants with hypotension during the first 24 hours of life.

STUDY DESIGN

ELBW infants with hypertension ≤ 30 weeks' gestation and ≤ 24 hours old randomly received treatment with vasopressin or dopamine in a blinded fashion. Normotensive infants not receiving vasopressor support served as a comparison group.

RESULTS

Twenty ELBW infants with hypertension received vasopressin (n = 10) or dopamine (n = 10), and 50 were enrolled for comparison. Mean gestational age was 25.6 ± 1.4 weeks and birth weight 705 ± 154 g. Response to vasopressin paralleled that of dopamine in time to adequate mean blood pressure (Kaplan-Meier curve, P = .986); 90% of infants in each treatment group responded with adequate blood pressure. The vasopressin group received fewer doses of surfactant (P < .05), had lower PaCO2 values (P < .05), and were not tachycardic (P < .001) during vasopressin administration, compared with the dopamine group.

CONCLUSIONS

Vasopressin in ELBW infants as the initial agent for early hypotension appeared safe. This pilot study supports a larger randomized controlled trial of vasopressin vs dopamine therapy in ELBW infants with hypotension.

Trends in pharmacotherapy for neonatal hypotension

OBJECTIVE

To determine trends in pharmacotherapy for neonatal hypotension in all infants and in extremely low birth weight (ELBW, birth weight 300-1000 g) infants.

STUDY DESIGN

We queried the Pediatric Health Information System database for all infants ≤28 days with a diagnosis code for hypotension that were discharged between January 2001 and December 2012. Patients were excluded if they had complex congenital heart disease or cardiac surgery, sepsis or meningitis, or had extracorporeal membrane oxygenation. We determined trends in pharmacotherapy for hypotension in all infants and ELBW infants, an especially vulnerable group.

RESULTS

A total of 8019 hypotensive infants met study criteria. The 2 most prescribed medications were dopamine (65.3%) and dobutamine (19.9%). For 1487 hypotensive ELBW infants, the 2 most prescribed medications were dopamine (83.4%) and hydrocortisone (33%). During the study period, the use of dobutamine decreased, and hydrocortisone and vasopressin use increased for all infants and for ELBW infants.

CONCLUSIONS

Treatment of neonatal hypotension varies widely between institutions and individual practitioners, and pharmacotherapy for neonatal hypotension has changed over the past decade. Although dopamine and dobutamine were the most frequently used agents, their use has declined and the uses of hydrocortisone and vasopressin have increased.

Acute kidney injury in the neonate

Critically ill neonates are at risk for acute kidney injury (AKI). AKI has been associated with increased risk of morbidity and mortality in adult and pediatric patients, and increasing evidence suggests a similar association in the neonatal population. This article describes the current AKI definitions (including their limitations), work on novel biomarkers to define AKI, diagnosis and management strategies, long-term outcomes after AKI, and future directions for much-needed research in this important area.

Effect of dopamine infusion on thyroid hormone tests and prolactin levels in very low birth weight infants

OBJECTIVE

To evaluate the effect of dopamine on thyroid hormone tests and prolactin (PRL) and to assess requirement for L-thyroxin (LT4).

METHODS

The infants (n = 102) were divided into three groups (Group 1; received no dopamine, Group 2 received ≤25 mg/kg cumulative dose and Group 3; received >25 mg/kg cumulative dose). Blood samples were taken at 6-8 days (timepoint 1), 13-15 days (timepoint 2), and 4-6 weeks of life (timepoint 3).

RESULTS

Respiratory distress syndrome was higher in group 2 and 3. Patnet ductus arteriosus was higher in group 3 than in groups 1 and 2. Duration and cumulative dose in group 3 were higher than group 2. There was no difference between thyroid hormones that were taken after stopping infusion at timepoint 3 among all groups. No therapy with LT4 was needed. PRL levels were higher at timepoint 1 in group 1 than compared to group 2 and 3 (p < 0.05), and no difference between group 2 and 3 (p > 0.05). This difference was disappeared at following timepoints.

CONCLUSIONS

The release of TSH, FT3, FT4 and PRL were not inhibited and prophylactic thyroid hormone treatment was not required in VLBW infants receiving dopamine infusions.

Neonatal cardiac care, a perspective

Every year in the United States approximately 40,000 infants are born with congenital heart disease. Several of these infants require corrective or palliative surgery in the neonatal period. Mortality rates after cardiac surgery are highest amongst neonates, particularly those born prematurely. There are several reasons for the increased surgical mortality risk in neonates. This review outlines these risks, with particular emphasis on the relative immaturity of the organ systems in the term and preterm neonate.

Observational study of cerebral hemodynamics during dopamine treatment in hypotensive ELBW infants on the first day of life

OBJECTIVE

To evaluate cerebral hemodynamics during dopamine treatment in hypotensive (mean arterial blood pressure (MABP)<gestational age) extremely low birth weight (ELBW) infants.

STUDY DESIGN

Continuous monitoring of cerebral blood flow velocity (CBFv), MABP and PCO2 was performed in hypotensive ELBW infants on the first day of life, beginning with an ∼15-min baseline reading and continued during advancing dopamine infusion until MABP was optimized. Physiological variables and CBFv reactivity were compared before and after MABP was optimized.

RESULT

Fifteen hypotensive ELBW infants (625±174 g; 24 (23 to 24.8) weeks) were studied. Mean CBFv increased from 10.9±3.7 to 15.7±5.7 cm s(-1) (P=0.001) simultaneously as MABP increased from 22.3±2.8 to 35.2±9.7 mm Hg (P<0.001). Mean CBFv reactivity (95% confidence interval (CI)) was 3.9 (1.6 to 6.2) %mm Hg(-1). Nine infants died and/or developed severe intraventricular hemorrhage (IVH).

CONCLUSION

Mean CBFv increased pressure-passively as MABP was optimized by dopamine treatment in very sick hypotensive ELBW infants on the first day of life.

A comparison of combination dopamine and epinephrine treatment with high-dose dopamine alone in asphyxiated newborn piglets after resuscitation

BACKGROUND

When asphyxiated neonates require additional cardiovascular support to moderate doses of dopamine infusion, controversy exists on the differential hemodynamic effects of two approaches (adding a second inotrope vs. increasing dopamine dosage). We hypothesized that high-dose dopamine (HD) would be detrimental to systemic and regional perfusion as compared with dopamine and epinephrine (D + E) combination therapy using a swine model of neonatal hypoxia-reoxygenation (H-R).

METHODS

Twenty-seven piglets (1-4 d, 1.5-2.5 kg) were used for continuous monitoring of systemic arterial pressure (mean arterial pressure, MAP) and pulmonary arterial pressure (PAP), cardiac output (cardiac index, CI), and carotid (carotid artery flow index, CAFI), superior mesenteric (superior mesenteric artery flow index), and renal arterial flows. H-R piglets underwent 2 h of hypoxia followed by 2 h of reoxygenation before drug infusion (2 h).

RESULTS

The hemodynamics of H-R piglets deteriorated gradually after reoxygenation. HD and D + E infusions improved CI similarly (both groups vs. control; P < 0.05). Both regimens increased MAP (P < 0.05) but not PAP, with decreased PAP/MAP ratio in D + E piglets. Both regimens improved CAFI and superior mesenteric artery flow index, with decreased mesenteric vascular resistance in HD-treated piglets. No significant effect on renal perfusion was observed.

CONCLUSION

In H-R newborn piglets treated with a moderate dose of dopamine, adding epinephrine or further increasing dopamine improved systemic hemodynamics similarly; these treatments have differential effects on the pulmonary and mesenteric circulations.

Cerebral vascular effects of hypovolemia and dopamine infusions: a study in newborn piglets

AIM

Despite widespread use, effects of volume boluses and dopamine in hypotensive newborn infants remain controversial. We aimed to elucidate if hypovolemia alone impairs cerebral autoregulation (CA) and if dopamine affects cerebral vasculature.

METHODS

In 12 piglets, cerebral perfusion (laser-Doppler flux) and oxygenation [near-infrared spectroscopy (NIRS)] were examined during dopamine (20-50 μg/kg per minute) and nonpharmacologically induced blood pressure (ABP) changes. Effect on cerebral perfusion and oxygenation was quantified as frequency gain between ABP and laser-Doppler flux (gain-LDF) and NIRS [gain-oxygenation index (OI)], respectively. Gain quantifies change in perfusion or oxygenation per ABP-change. CA was estimated as gain-LDF during nonpharmacologically induced ABP changes, that is, as degree of impairment. Dopamine's cerebrovascular effect was estimated by contrasting gain during dopamine- and nonpharmacologically induced ABP changes. Measurements were conducted during both normovolemia- and haemorrhage-induced hypovolemia.

RESULTS

Hypovolemia elicited hypotension (p = 0.02) as well as increasing impairment of CA (p = 0.01). However, hypovolemia without hypotension did not affect CA significantly. Dopamine increased perfusion significantly compared to nonpharmacological challenges (mean difference: 1.5%/mmHg, 95% CI: 0.5-2.6, p = 0.007). Oxygenation was, however, similar (mean difference: 0.01 μmol/L per mmHg, 95% CI: -0.03 to 0.05, p = 0.7).

CONCLUSION

Our findings do not support that hypovolemia alone impairs CA. Furthermore, dopamine seems to increase cerebral perfusion but not oxygenation.

Effect of dopamine on peripheral perfusion in very-low-birth-weight infants during the transitional period

INTRODUCTION

Dopamine is one of the most frequently used inotropic drugs in neonatal intensive care units (NICUs); however, it does not seem to improve outcomes in premature infants. Given that the ultimate aim of cardiovascular management is to stabilize and maintain organ perfusion, an understanding of dopamine's effects on organ blood flow will help in judging when to use dopamine and how to titrate the dosage. Such an approach can lead to improved outcomes. This study aimed to evaluate the effects of dopamine on peripheral perfusion in very-low-birth-weight (VLBW) infants within 72 h of birth.

METHODS

This prospective observational study identified and sampled 44 instances of initiation of dopamine treatment or increase in dopamine dose in 29 VLBW infants. Blood pressure, heart rate, and skin and subcutaneous blood flow were measured and compared before and after each instance.

RESULTS

Blood pressure and skin and subcutaneous blood flow in the lower limbs increased after initiation of dopamine treatment or after dose increase.

DISCUSSION

Dopamine increases blood pressure as well as skin and subcutaneous blood flow in VLBW infants despite its supposed vasoconstrictive action, indicating that it increases both perfusion pressure and blood flow and is devoid of overwhelming peripheral vasoconstrictive effects.

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

A solid understanding of the mechanisms of action of cardiovascular medications used in clinical practice along with efforts to develop comprehensive hemodynamic monitoring systems to improve the ability to accurately identify the underlying pathophysiology of cardiovascular compromise are essential in the management of neonates with shock. This article reviews the mechanisms of action of the most frequently used cardiovascular medications in neonates. Because of paucity of data from controlled clinical trials, evidence-based recommendations for the clinical use of these medications could not be made. Careful titration of the given medication with close monitoring of the cardiovascular response might improve the effectiveness and decrease the risks associated with administration of these medications.

Effect of antihypotensive treatment on cerebral oxygenation of preterm infants without PDA

BACKGROUND

Preterm infants with hypotension (mean arterial blood pressure [MABP] < gestational age [GA]) are treated with volume expansion and/or dopamine to ensure adequate cerebral perfusion/oxygenation. We used near-infrared spectroscopy to analyze the effects of volume expansion and dopamine on cerebral oxygenation in hypotensive preterm infants without patent ductus arteriosus (PDA).

PATIENTS AND METHODS

Among 390 infants, 71 (GA < 32 weeks) were hypotensive and eligible for inclusion. Thirty-three infants received volume expansion only (NaCl 0.9%; 20 mL/kg), and 38 received additional dopamine (5 μg/kg per minute). Nine and 11 infants initially treated with dopamine subsequently needed 7.5 and 10 μg/kg per minute, respectively. Seventy-one infants without hypotension were individually matched to serve as controls. MABP, regional cerebral oxygen saturation (rSco(2)), fractional tissue oxygen extraction (cFTOE), and arterial saturation (Sao(2)) were monitored 15 minutes before and 30 and 60 minutes after volume or dopamine and at comparable postnatal ages in controls.

RESULTS

No changes in MABP, rSco(2), or cFTOE were found 30 minutes after volume expansion. MABP increased 60 minutes after 5 μg/kg per minute dopamine (median [range]: 28 [19-32] vs 33 [23-46] mm Hg; P < .001). There was a small increase and decrease, respectively, in rSco(2) (63 [43-84] vs 66 [46-87]%; P < .05) and cFTOE (0.33 [0.14-0.56] vs 0.31 [0.07-0.54]1/1; P < .05). However, no differences were found at any time point between controls and infants treated with volume or additional dopamine (5, 7.5, and 10 μg/kg per minute) for rSco(2) or cFTOE.

CONCLUSIONS

Volume expansion and additional dopamine do not cause any significant change in rSco(2) or cFTOE in hypotensive preterm infants without PDA. We speculate that very preterm infants with hypotension but without signs of a compromised cerebral oxygenation and systemic perfusion might not be in need of antihypotensive therapy.

Dose-dependent hemodynamic and metabolic effects of vasoactive medications in normotensive, anesthetized neonatal piglets

The developmentally regulated hemodynamic effects of vasoactive medications have not been well characterized. We used traditional and near-infrared spectroscopy monitoring technologies and investigated the changes in heart rate, blood pressure, common carotid artery (CCA) blood flow (BF), cerebral, renal, intestinal, and muscle regional tissue O2 saturation, and acid-base and electrolyte status in response to escalating doses of vasoactive medications in normotensive anesthetized neonatal piglets. We used regional tissue O2 saturation and CCA BF as surrogates of organ and systemic BF, respectively, and controlled minute ventilation and oxygenation. Low to medium doses of dopamine, epinephrine, dobutamine, and norepinephrine increased blood pressure and systemic and regional BF in a drug-specific manner, whereas milrinone exerted minimal effects. At higher doses, dopamine, epinephrine, and norepinephrine but not dobutamine decreased systemic, renal, intestinal, and muscle BF, while cerebral BF remained unchanged. Epinephrine induced significant increases in muscle BF and serum glucose and lactate concentrations. The findings reveal novel drug- and dose-specific differences in the hemodynamic response to escalating doses of vasoactive medications in the neonatal cardiovascular system and provide information for future clinical studies investigating the use of vasoactive medications for the treatment of neonatal cardiovascular compromise.

Haemodynamically unstable preterm infant: an unresolved management conundrum

While extremely low-birthweight infants are at a higher risk of haemodynamic instability, management strategies can be highly variable and may lack scientific validation. The aetiology of cardiovascular compromise can be diverse. Volume replacements, cardiotropes (dobutamine, dopamine, epinephrine and milrinone) and hydrocortisone supplementation are common interventions. Most often, therapy is driven by protocol, is based on poorly validated clinical information or is based on the premise that "one therapy fits all". A physiology-driven approach is most needed during transition from intrauterine to extrauterine life surrounding preterm birth, when rapid changes in cardiovascular adaptation occur. The physiologically important determinants of neonatal haemodynamics include cardiac output and systemic vascular resistance, blood pressure, as well as individual organ vascular resistances and blood flows. Three key variables with impact on neonatal haemodynamics, haemodynamically significant ductus arteriosus, systemic blood flow and left ventricular afterload, as well as related therapeutic dilemmas are addressed. Among the novel technologies and approaches presently available, targeted neonatal echocardiography performed by the clinician, used in conjunction with the clinical context, has the potential to better define pathophysiology. A framework for physiology-driven care is proposed, which has the potential to optimize care.

Developmental changes in catecholamine requirement, volume load and corticosteroid supplementation in premature infants born at 22 to 28 weeks of gestation

BACKGROUND

Due to circulatory instability, premature infants require volume loads, catecholamines and steroid supplementation to improve mortality and neurodevelopmental outcome. However, a complete quantitative analysis concerning the relationship between supplementation and gestational age, especially in infants born at 22 to 24 weeks of gestation, is lacking.

AIM

To investigate whether less mature infants need higher doses of catecholamine, volume loads and steroid, and whether those who require higher doses have poorer outcome.

STUDY DESIGN

A retrospective, observational study was performed at a tertiary center in a university setting. Among the consecutive 221 premature infants born at 22 to 28 weeks of gestation, we selected 108 infants who had no apparent pathological conditions other than prematurity. Catecholamines, volume loads and steroid, given to attain sufficient blood pressure and urinary output, were quantitatively analyzed during the first 24 hours.

OUTCOME MEASURES

Quantity of catecholamines, volume expanders and steroid supplementation as a function of gestational age and childhood outcome at 2 years.

RESULTS

Catecholamines and volume loads were increased in a step-wise manner with decreasing gestational age. Intact survival rate was significantly lower in infants born before 25 weeks of gestation compared with the more mature infants. Among infants born at 22 to 24 weeks' gestation, catecholamine and volume load increased significantly in poor outcome infants compared with good outcome infants.

CONCLUSIONS

From a developmental viewpoint, progressively larger doses of catecholamine, volume expanders and corticosteroid are required to stabilize circulatory adaptation to neonatal life in infants between 22 to 28 weeks of gestation.

Hypotension and shock in the preterm neonate

While the methods of establishing and maintaining organ perfusion differ from one clinician to the next, the underlying physiological rationale remains constant. The gestalt for correcting circulatory compromise is generally performed in a stepwise manner; first ensuring that the vasculature is filled, then administering medications to tighten the vasculature, and lastly, compensating for an immature vasculature. This stepwise approach is reflected in the pharmacological interventions of providing fluid boluses (filling the pump), giving catecholamines (tightening the pump), and starting hydrocortisone (compensating for an immature pump). While the stepwise management approach may be familiar to some nurses, it is important to understand the evidence-based rationale that supports clinical decisions. This article will outline physiology unique to the neonate, clarify terminology that surrounds hypotension and shock, and explore various methods for the treatment of circulatory compromise in the preterm neonate.

Arrhythmia in the neonatal intensive care unit

A random sample of 457 neonates was prospectively studied in order to identify the incidence, common types, and risk factors for arrhythmias in the neonatal intensive care unit (NICU). A 12-lead EKG was studied in all neonates (n = 457). A total of 139 Holter studies was done in every fourth baby with a normal EKG (n = 100) and in all babies with an abnormal EKG (n = 39). Of the 100 infants who were thought to be arrhythmia-free by EKG, nine infants demonstrated an arrhythmia on Holter studies. When we correlated screening results with maternal, obstetrical, and neonatal risk factors; arrhythmias were significantly associated with male gender, more mature gestational age, lower glucose levels, maternal smoking, high umbilical artery lines, and the use of the nebulized beta-2 adrenergic treatment, whereas umbilical venous lines and dopamine infusion did not relate to arrhythmia. We conclude that arrhythmias are more common in the NICU than in the general neonatal population. Compared to Holter monitoring, the sensitivity of the EKG was only 89%.

Hypotension in preterm infants with significant patent ductus arteriosus: effects of dopamine

OBJECTIVE

To study the effects of dopamine on systemic arterial pressure (SAP) and systemic blood flow (SBF) (estimated with the superior vena cava [SVC] flow) in preterm infants with hypotension and patent ductus arteriosus (PDA).

STUDY DESIGN

Clinical and echocardiographic variables were measured before and 2 hours after starting dopamine in premature infants <32 weeks gestational age with PDA and systemic hypotension.

RESULTS

Seventeen premature infants were included (gestational age, 28+/-2 weeks; birth weight, 1030 +/- 400 g). A mean rate of 8 +/- 2 microg/kg/min of dopamine raised SAP from 30 +/- 3 to 41 +/- 5 mm Hg (P < .05), and the pulmonary artery pressures from 25 +/- 5 to 32 +/- 8 mm Hg (P < .05). The SVC flow increased by 30% (from 130 +/- 40 to 170 +/- 44 mL/kg/min; P < .05). The left ventricular output and the end-diastolic and mean left pulmonary artery blood flow velocities did not change despite the increase in pulmonary artery pressure.

CONCLUSION

In preterm infants with hypotension and PDA, dopamine (<10 microg/kg/min) increases the systemic blood pressure and the systemic blood flow. Our results suggest that dopamine decreases left-to-right shunting across ductus arteriosus, caused by a rise in pulmonary vascular resistances.

Dopamine versus dobutamine in very low birthweight infants: endocrine effects

OBJECTIVES

To compare the endocrine effects of dopamine and dobutamine in hypotensive very low birthweight (VLBW) infants.

DESIGN

Non-blinded randomised prospective trial.

SETTING

Level III neonatal intensive care unit.

PATIENTS

35 hypotensive VLBW infants who did not respond to volume loading, assigned to receive dopamine or dobutamine.

MEASUREMENTS

Haemodynamic variables and serum levels of thyroid stimulating hormone (TSH), total thyroxine (T(4)), prolactin (PRL) and growth hormone were assessed during the first 72 h of treatment and the first 72 h after stopping treatment.

RESULTS

Demographic and clinical data did not significantly differ between the two groups. Necessary cumulative and mean drug doses and maximum infusion required to normalise blood pressure were significantly higher in the dobutamine than in the dopamine group (p<0.01). Suppression of TSH, T(4) and PRL was observed in dopamine-treated newborns from 12 h of treatment onwards, whereas levels of growth hormone reduced significantly only at 12 h and 36 h of treatment (p<0.01). TSH, T(4) and PRL rebound was observed from the first day onwards after stopping dopamine. Dobutamine administration did not alter the profile of any of the hormones and no rebound was observed after stopping treatment.

CONCLUSION

Dopamine and dobutamine both increase the systemic blood pressure, though dopamine is more effective. Dopamine reduces serum levels of TSH, T(4) and PRL in VLBW infants but such suppression is quickly reversed after treatment is stopped. Further research is required to assess if short-term iatrogenic pituitary suppression has longer-term consequences.

[Is there still a place for dopamine in the paediatric critical care setting?]

Dopamine is mostly used in patients with cardiogenic or septic shock, but its place in critical care medicine is often questioned. Dopamine, of which pharmacology in children is variable, is prescribed for its inotropic effect, associated with an increase in cardiac output and at a lesser degree blood pressure. Beneficial effects (need for renal replacement therapy and mortality) of low dose in patients at risk of, or with acute renal failure are not demonstrated. Dopamine has numerous potential deleterious effects on local circulations (pulmonary, cerebral, coronary and cutaneous), respiratory function, gastroduodenal motility, endocrine function (further depression of the hypothalamic-pituitary axis induced by stress) and immunity (partially due to decreased production of prolactin). Finally, in shocked adults dopamine infusion might be associated with an increase in mortality rate. Dopamine remains the most prescribed catecholamine, either in adults or children. It still is one of the first line drug included in the recent recommendations for the treatment of septic shock (norepinephrine tends to replace it), cardiogenic shock (dobutamine is the first drug), severe head trauma, and organ donor in cerebral death. In conclusion, if dopamine is today less used, there is no proof that its deleterious effects are associated with an excess of mortality. Thus, dopamine still is part of the stock of drugs that act on the cardiocirculatory system (but for how long?).