Controversies in the diagnosis and management of hypotension in the newborn infant

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.

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.

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.

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.

Assessment of a downsized potassium adsorption filter designed to transfuse neonates

BACKGROUND

During storage, the potassium level of red blood cell (RBC) components increases, especially after irradiation. Neonates are prone to hyperkalemia, for example, non-oliguric hyperkalemia, so using potassium adsorption filters during transfusion may be helpful. To overcome dilution of RBC components caused by saline priming of existing potassium adsorption filters, a downsized potassium adsorption filter for neonates (PAF-n, Kawasumi Laboratories Inc., Tokyo, Japan) was developed.

STUDY DESIGN AND METHODS

To assess the performance of PAF-n, its adsorption efficiency and RBC recovery rate were evaluated by testing pre-filtration and serial post-filtration (0-30 mL, 30-60 mL, 60-90 mL, and 90-120 mL) samples from 8 RBC components.

RESULTS

The average potassium adsorption rate of the PAF-n was 90.5% ± 0.78%, and never less than 89.0% in any of 8 RBC components. RBC recovery rates were 99.3% ± 1.12%.

CONCLUSION

The PAF-n showed an effective potassium ability with negligible RBC dilution.

Evaluation of the causal effects between dopamine infusion changeover and fluctuations in mean arterial pressure in neonates

OBJECTIVE

To evaluate whether changing dopamine infusions every 12 hours and preparing these infusions 30 min before administration reduces blood pressure fluctuations in preterm and term neonates.

DESIGN

This was a retrospective study using data from live patients on the neonatal unit and prospective study exploring stability of infusions in a laboratory-based neonatal ward simulation.

SETTING

Single-centre study in a tertiary neonatal surgical unit in a university teaching hospital.

PATIENTS

Neonates who received more than one subsequent dopamine infusion and had invasive arterial blood pressure monitoring, during their admission in the neonatal unit, were included.

INTERVENTIONS

As part of the Quality Improvement project, the standard operating procedure (SOP) was changed, and dopamine infusions were prepared by nursing staff and left to rest for 30 min before administering to the neonate. Additionally, infusions were replaced every 12 hours.

MAIN OUTCOME MEASURES

The percentage change in mean arterial pressure (MAP) and the percentage loss in the drug concentration during infusion during changeover.

RESULTS

Our findings indicate that up to 15% of the initial dopamine concentration is lost after 24 hours. This results in a sharp variation in the dopamine concentration during infusion changeover that correlates with observed rapid fluctuations in MAP. In changing the SOP, no significant difference in the concentration of dopamine and MAP were observed over 12 hours.

CONCLUSIONS

Delaying administration of dopamine infusions by 30 min after preparation combined with changing infusions 12 hourly has reduced MAP fluctuations. Therefore, the risks associated with MAP fluctuations, including intraventricular haemorrhages, are reduced.

Surviving sepsis campaign international guidelines for the management of septic shock and sepsis-associated organ dysfunction in children

OBJECTIVES

To develop evidence-based recommendations for clinicians caring for children (including infants, school-aged children, and adolescents) with septic shock and other sepsis-associated organ dysfunction.

DESIGN

A panel of 49 international experts, representing 12 international organizations, as well as three methodologists and three public members was convened. Panel members assembled at key international meetings (for those panel members attending the conference), and a stand-alone meeting was held for all panel members in November 2018. A formal conflict-of-interest policy was developed at the onset of the process and enforced throughout. Teleconferences and electronic-based discussion among the chairs, co-chairs, methodologists, and group heads, as well as within subgroups, served as an integral part of the guideline development process.

METHODS

The panel consisted of six subgroups: recognition and management of infection, hemodynamics and resuscitation, ventilation, endocrine and metabolic therapies, adjunctive therapies, and research priorities. We conducted a systematic review for each Population, Intervention, Control, and Outcomes question to identify the best available evidence, statistically summarized the evidence, and then assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. We used the evidence-to-decision framework to formulate recommendations as strong or weak, or as a best practice statement. In addition, "in our practice" statements were included when evidence was inconclusive to issue a recommendation, but the panel felt that some guidance based on practice patterns may be appropriate.

RESULTS

The panel provided 77 statements on the management and resuscitation of children with septic shock and other sepsis-associated organ dysfunction. Overall, six were strong recommendations, 49 were weak recommendations, and nine were best-practice statements. For 13 questions, no recommendations could be made; but, for 10 of these, "in our practice" statements were provided. In addition, 52 research priorities were identified.

CONCLUSIONS

A large cohort of international experts was able to achieve consensus regarding many recommendations for the best care of children with sepsis, acknowledging that most aspects of care had relatively low quality of evidence resulting in the frequent issuance of weak recommendations. Despite this challenge, these recommendations regarding the management of children with septic shock and other sepsis-associated organ dysfunction provide a foundation for consistent care to improve outcomes and inform future research.

Surviving Sepsis Campaign International Guidelines for the Management of Septic Shock and Sepsis-Associated Organ Dysfunction in Children

OBJECTIVES

To develop evidence-based recommendations for clinicians caring for children (including infants, school-aged children, and adolescents) with septic shock and other sepsis-associated organ dysfunction.

DESIGN

A panel of 49 international experts, representing 12 international organizations, as well as three methodologists and three public members was convened. Panel members assembled at key international meetings (for those panel members attending the conference), and a stand-alone meeting was held for all panel members in November 2018. A formal conflict-of-interest policy was developed at the onset of the process and enforced throughout. Teleconferences and electronic-based discussion among the chairs, co-chairs, methodologists, and group heads, as well as within subgroups, served as an integral part of the guideline development process.

METHODS

The panel consisted of six subgroups: recognition and management of infection, hemodynamics and resuscitation, ventilation, endocrine and metabolic therapies, adjunctive therapies, and research priorities. We conducted a systematic review for each Population, Intervention, Control, and Outcomes question to identify the best available evidence, statistically summarized the evidence, and then assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. We used the evidence-to-decision framework to formulate recommendations as strong or weak, or as a best practice statement. In addition, "in our practice" statements were included when evidence was inconclusive to issue a recommendation, but the panel felt that some guidance based on practice patterns may be appropriate.

RESULTS

The panel provided 77 statements on the management and resuscitation of children with septic shock and other sepsis-associated organ dysfunction. Overall, six were strong recommendations, 52 were weak recommendations, and nine were best-practice statements. For 13 questions, no recommendations could be made; but, for 10 of these, "in our practice" statements were provided. In addition, 49 research priorities were identified.

CONCLUSIONS

A large cohort of international experts was able to achieve consensus regarding many recommendations for the best care of children with sepsis, acknowledging that most aspects of care had relatively low quality of evidence resulting in the frequent issuance of weak recommendations. Despite this challenge, these recommendations regarding the management of children with septic shock and other sepsis-associated organ dysfunction provide a foundation for consistent care to improve outcomes and inform future research.

Blood pressure intervention levels in preterm infants: pilot randomised trial

OBJECTIVE

To examine the feasibility of a trial allocating different blood pressure (BP) intervention levels for treatment in extremely preterm infants.

DESIGN

Three-arm open randomised controlled trial performed between February 2013 and April 2015.

SETTING

Single tertiary level neonatal intensive care unit.

PATIENTS

Infants born <29 weeks' gestation were eligible to participate, if parents consented and they did not have a major congenital malformation.

INTERVENTIONS

Infants were randomised to different levels of mean arterial BP at which they received cardiovascular support: active (<30 mm Hg), moderate (<gestational age mm Hg) or permissive (signs of poor perfusion or <19 mm Hg). Once this threshold was breached, all were managed using the same treatment guideline. BP profiles were downloaded continuously; cardiac output and carotid blood flow were measured at 1 day and 3 days, and amplitude integrated EEG was recorded during the first week. Cranial ultrasound scans were reviewed blind to study allocation.

MAIN OUTCOME MEASURE

Inotrope usage and achieved BP.

RESULTS

Of 134 cases screened, 60 were enrolled, with mean gestation 25.8 weeks (SD 1.5) and birth weight 817 g (SD 190). Invasively measured BP on the first day and inotrope usage were highest in the active and lowest in the permissive arms. There were no differences in haemodynamic or EEG variables or in clinical complications. Predefined cranial ultrasound findings did not differ significantly; no infants in the active arm had parenchymal brain lesions.

CONCLUSION

The BP threshold used to trigger treatment affects the achieved BP and inotrope usage, and it was possible to explore these effects using this study design.

TRIAL REGISTRATION NUMBER

ISRCTN83507686.

Prolonged second stage labour and consequences of hypoxia in the neonate: A review

Hypoxia due to dystocia and its repercussions are serious issues concerning the health of neonates. In order to gain a better understanding of the cause and especially the effects and potential long-term disorders, a critical analysis of peer-reviewed literature was made. As shown by many authors, initially the most devastating peripartal cause of ill health in neonates is associated with the serious effects of prolonged and severe acidosis. Other life threatening complications are related to disorders such as meconium aspiration syndrome (MAS), neonatal respiratory distress syndrome, hypoxic ischaemic encephalopathy and necrotising enterocolitis. Despite the astonishing ability of neonates to compensate mixed metabolic and respiratory acidosis with breathing onset directly postpartum, the longer second stage labour takes and the more extreme the acidosis is, the more detrimental its consequences. Lungs are especially vulnerable in this phase of life, aspired meconium can result in increased expression of pro-inflammatory chemotactic cytokines, phospholipase A2 and PGE2 levels , exacerbating inflammatory reactions of lung tissue and exerting a deleterious effect on alveolar cells. Neonates experiencing dystocia could greatly benefit from administration of buffering substances and non-steroidal anti-inflammatory drugs.

Hypotension within 1 week of life associated with poor short- and long-term outcomes in very low birth weight infants

We examined whether hypotension in very low birth weight infants aged⩽1 week was associated with hospital morbidities and overall mortality. Further, we studied whether hypotension was associated with poor neurodevelopmental outcomes in these patients at the corrected age of 18 months. A total of 166 very low birth weight infants were studied during this period. Hospital outcomes and neurodevelopmental outcomes at the corrected age of 18 months were evaluated. Among the 166 very low birth weight infants, 95 patients (57.2%) experienced hypotension at⩽1 week and were associated with an increased incidence of morbidities and mortality. At the corrected age of 18 months, hypotension of the⩽1 week group had significantly lower scores in all three - cognitive, language, and motor - composites of the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) screening tests. In addition, a multivariable logistic regression analysis showed that longer mechanical ventilation and periventricular leukomalacia were additionally associated with worse cognitive and language neurodevelopmental outcomes. Hypotension in very low birth weight infants within 1 week of life was associated with increased morbidities and overall mortality. It was also associated with an increased risk of cognitive and language outcomes.

Advances in Diagnosis and Management of Hemodynamic Instability in Neonatal Shock

Shock in newborn infants has unique etiopathologic origins that require careful assessment to direct specific interventions. Early diagnosis is key to successful management. Unlike adults and pediatric patients, shock in newborn infants is often recognized in the uncompensated phase by the presence of hypotension, which may be too late. The routine methods of evaluation used in the adult and pediatric population are often invasive and less feasible. We aim to discuss the pathophysiology in shock in newborn infants, including the transitional changes at birth and unique features that contribute to the challenges in early identification. Special emphasis has been placed on bedside focused echocardiography/focused cardiac ultrasound, which can be used as an additional tool for early, neonatologist driven, ongoing evaluation and management. An approach to goal oriented management of shock has been described and how bed side functional echocardiography can help in making a logical choice of intervention (fluid therapy, inotropic therapy or vasopressor therapy) in infants with shock.

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.

Understanding the Stability of Dopamine and Dobutamine Over 24 h in Simulated Neonatal Ward Conditions

OBJECTIVES

Our objectives were to investigate the possible effects of temperature and light on the stability of dopamine and dobutamine continuous infusions over 24 h when prepared in a variety of dilution vehicles.

METHODS

Syringe-driver infusion apparatuses were set up for dopamine and dobutamine diluted with either 0.9% sodium chloride (NaCl) or 5% glucose delivering 3 and 5 μg/kg/min, respectively, via 206-cm extension sets. All infusions were prepared for a neonate weight of 1 kg. Infusions were run over 24 h with approximately half the tubing within an incubator set at 35 °C. Cyclic voltammetry was used to monitor the concentration of the inotrope within the syringe and at the end of the extension set, both initially and after 24 h.

RESULTS

The variation in the concentration of dopamine and dobutamine in the vials (n = 6) was 3.58 and 1.22%, respectively. This variation increased to 10.88% for dopamine and 5.76% for dobutamine in the syringe. After 24 h, a significant reduction in the concentration of dopamine was observed at the end of the extension set when prepared in 0.9% NaCl versus 5% glucose (p < 0.001; n = 6-7) and in dobutamine when prepared in 0.9% NaCl (p < 0.001; n = 6-7). No differences in the concentration of dopamine prepared in 0.9% NaCl were observed after 24 h in light-exposed and light-protected extension sets (n = 6-7).

CONCLUSIONS

Dobutamine is more stable in dilution vehicles than dopamine, and inotropes are more stable in the 5% glucose dilution vehicle than in 0.9% NaCl. Such findings will provide guidance on the choice of inotropes.

The CLOSED trial; CLOnidine compared with midazolam for SEDation of paediatric patients in the intensive care unit: study protocol for a multicentre randomised controlled trial

INTRODUCTION

Sedation is an essential part of paediatric critical care. Midazolam, often in combination with opioids, is the current gold standard drug. However, as it is a far-from-ideal agent, clonidine is increasingly being used in children. This drug is prescribed off-label for this indication, as many drugs in paediatrics are. Therefore, the CLOSED trial aims to provide data on the pharmacokinetics, safety and efficacy of clonidine for the sedation of mechanically ventilated patients in order to obtain a paediatric-use marketing authorisation.

METHODS AND ANALYSIS

The CLOSED study is a multicentre, double-blind, randomised, active-controlled non-inferiority trial with a 1:1 randomisation between clonidine and midazolam. Both treatment groups are stratified according to age in three groups with the same size: <28 days (n=100), 28 days to <2 years (n=100) and 2-18 years (n=100). The primary end point is defined as the occurrence of sedation failure within the study period. Secondary end points include a pharmacokinetic/pharmacodynamic relationship, pharmacogenetics, occurrence of delirium and withdrawal syndrome, opioid consumption and neurodevelopment in the neonatal age group. Logistic regression will be used for the primary end point, appropriate statistics will be used for the secondary end points.

ETHICS

Written informed consent will be obtained from the parents/caregivers. Verbal or deferred consent will be used in the sites where national legislation allows. The study has institutional review board approval at recruiting sites. The results will be published in a peer-reviewed journal and shared with the worldwide medical community.

TRIAL REGISTRATION

EudraCT: 2014-003582-24; Clinicaltrials.gov: NCT02509273; pre-results.

Presepsin for the detection of early-onset sepsis in preterm newborns

BACKGROUND

Early-onset sepsis (EOS) is responsible for an important fraction of neonatal morbidity and mortality all over the world. The aim of this study was to assess whether presepsin (P-SEP) can be a more accurate biomarker of EOS compared with pro-calcitonin (PCT) and C-reactive protein (CRP).

STUDY DESIGN

Consecutive preterm neonates (<34 wk gestational age, admitted to Neonatal Intensive Care Unit by 6 h of age and undergoing sepsis evaluation) were recruited as part of a case-matched control study. We determined CRP, PCT and P-SEP at admission, and then at 12, 24, and 48 h of age. Neonates recruited into the study were divided into the EOS group (n = 32) and the uninfected group (n =38) according to their infection screening.

RESULTS

P-SEP values were significantly higher in the EOS group than in the uninfected group at different time intervals. The highest accuracy was achieved by P-SEP at 24 h after birth. The AUC for P-SEP was 0.97. In our sample, P-SEP achieved the best accuracy for prediction of EOS at the cut-off of 788 ng/l with 93% sensitivity and 100% specificity.

CONCLUSIONS

This study shows that P-SEP is significantly higher in preterm infants with EOS compared with uninfected infants.

Golden 60 minutes of newborn's life: Part 1: Preterm neonate

"Golden 60 minutes "or "Golden Hour" is defined as the first hour of the newborn after birth. This hour includes resuscitation care, transport to nursery from place of birth and course in nursery. The concept of "Golden hour" includes evidence based interventions that are done in the first 60 min of postnatal life for the better long term outcome of the preterm newborn especially extreme premature, extreme low birth weight and very low birth weight. The evidence shows that the concept of "Golden 60 minutes" leads to reduction in neonatal complications like hypothermia, hypoglycemia, intraventricular hemorrhage, chronic lung disease and retinopathy of prematurity. In this review, we have covered various interventions included in "Golden hour" for preterm newborn namely delayed cord clamping, prevention of hypothermia, respiratory and cardiovascular system support, prevention of sepsis, nutritional support and communication with family.

Low epinephrine levels and selective deficiency of β2-adrenoceptor vasodilation at birth

AIMS

Epinephrine is unique among biogenic catecholamines as a potent agonist of β2-adrenoceptors. The β2-adrenoceptor mediated effects during development might be linked to the increase of epinephrine synthesis. Our purpose was to characterize β-adrenoceptor-mediated relaxation in the aorta of newborn and young rabbits (3 to 4months old), and to relate those responses with the epinephrine content of the adrenal gland.

MAIN METHODS

The epinephrine levels and the tyrosine hydroxylase activity were determined in adrenal glands of newborn and young rabbits. Also, concentration-response curves to phenylephrine (selective α1-adrenoceptor agonist), dobutamine (selective β1-adrenoceptor agonist), terbutaline (selective β2-adrenoceptor agonist), and CL 316243 (selective β3-adrenoceptor agonist) were determined in isolated aortic rings obtained from both groups.

KEY FINDINGS

The adrenal gland content and the plasma concentrations of epinephrine were lower in newborn than in young rabbits. In contrast, the tyrosine hydroxylase activity was higher in newborn than in young rabbits. On the other hand, the maximal response to phenylephrine was lower in newborn than in young rabbits. Terbutaline at concentrations selective for β2-adrenoceptors had no relaxing effects in neonates, in contrast to young rabbits. The potency and the maximal response of neither dobutamine nor CL 316243 were significantly different between the two groups.

SIGNIFICANCE

In rabbits, as well as in humans, β2-adrenoceptor-mediated responses and epinephrine synthesis are both immature at birth. On the other hand, the β1 and β3-adrenoceptor-mediated responses are fully developed. We conclude that epinephrine may influence the development of the β2-adrenoceptor-mediated responses at birth and the rabbit is an excellent model to study these issues.

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.

Transitional Hemodynamics in Preterm Neonates: Clinical Relevance

BACKGROUND

Each newborn enters this world facing tremendous respiratory, hemodynamic and neuroendocrine challenges while going through drastic physiological changes during the process of adaption from fetal to postnatal life. Even though the vast majority of term infants transition smoothly without apparent consequences, this task becomes increasingly arduous for the extremely preterm infant.

METHODS & RESULTS

This article reviews the physiology and pathophysiology of cardiovascular adaptation of the very preterm neonate. In particular it describes the physiology of fetal circulation, summarizes the hemodynamic changes occurring during preterm births and discusses the impact of the most frequently seen clinical scenarios that place additional burden on the premature infant during immediate transition. Finally an emphasis is placed on discussing common clinical dilemmas and practical aspects of developmental hemodynamics such as neonatal hypotension and patent ductus arteriosus; clinical presentations the neonatologist encounters on a daily basis.

CONCLUSION

The review provides a physiology-based view on the hemodynamics of the immediate postnatal transitional period.

Catecholamine-resistant hypotension and myocardial performance following patent ductus arteriosus ligation

OBJECTIVE

We performed a multicenter study of preterm infants, who were about to undergo patent ductus arteriosus ligation, to determine whether echocardiographic indices of impaired myocardial performance were associated with subsequent development of catecholamine-resistant hypotension following ligation.

STUDY DESIGN

A standardized treatment approach for hypotension was followed at each center. Infants were considered to have catecholamine-resistant hypotension if their dopamine infusion was > 15 μg kg(-1)min(-1). Echocardiograms and cortisol measurements were obtained between 6 and 14 h after the ligation (prior to the presence of catecholamine-resistant hypotension).

RESULT

Forty-five infants were enrolled, 10 received catecholamines (6 were catecholamine-responsive and 4 developed catecholamine-resistant hypotension). Catecholamine-resistant hypotension was not associated with decreased preload, shortening fraction or ventricular output. Infants with catecholamine-resistant hypotension had significantly lower levels of systemic vascular resistance and postoperative cortisol concentration.

CONCLUSION

We speculate that low cortisol levels and impaired vascular tone may have a more important role than impaired cardiac performance in post-ligation catecholamine-resistant 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.

Comparison between oscillometric and intra-arterial blood pressure measurements in ill preterm and full-term neonates

Conflicting data exist regarding the accuracy of the oscillometric method of blood pressure (BP) measurement in neonates. There is limited data regarding intra-arterial BP trends in neonates. We aimed to determine the accuracy of oscillometric BP measurements and to evaluate the BP distributions in ill neonates. A total of 1492 simultaneously obtained oscillometric and intra-arterial (umbilical arterial [UAC] or radial arterial) BP measurements were used for comparisons and 125,580 intra-arterial BP readings were used to the evaluate BP distribution. There was a statistically significant difference (P < .0001) between the oscillometric and radial mean arterial BP (MAP) 4.8 ± 9.8 mm Hg, systolic BP 8.3 ± 11.6 mm Hg, diastolic BP 4.3 ± 9.3 mm Hg and between the oscillometric and UAC systolic BP 5.2 ± 11.9 mm Hg and diastolic BP -0.8 ± 10.4 mm Hg. The MAP increased with increases in weight (35.3 ± 4.92 mm Hg/kg), post-menstrual age (-0.29 ± 1.41 mm Hg/week) and advanced gestational age at birth (13.12 ± 0.90 mm Hg/week). Oscillometric BP measurements are not equivalent to the intra-arterial (UAC or radial arterial) BP in ill neonates. The BP increases with increase in weight, gestational age at birth, and post-menstrual age in ill neonates.

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.

Vasopressin and its analogues for the treatment of refractory hypotension in neonates

BACKGROUND

Neonatal hypotension that is refractory to volume expansion, catecholamines, or corticosteroids has a mortality of about 50%. Optimization of blood pressure and tissue perfusion in refractory hypotension may be crucial to improve clinical outcomes. Vasopressin, a neuropeptide hormone, or its analogue terlipressin has been used to treat refractory hypotension in neonates and may be effective.

OBJECTIVES

Our primary objective was to evaluate the efficacy and safety of vasopressin and its synthetic analogues (e.g. terlipressin) in decreasing mortality and adverse neurodevelopmental outcomes, and improving survival in neonates with refractory hypotension. Our secondary objectives were to determine the effects of vasopressin and its analogues (terlipressin) on improvement in blood pressure, increase in urine output, decrease in inotrope score, necrotizing enterocolitis (NEC), periventricular leukomalacia, intraventricular hemorrhage, chronic lung disease, and retinopathy of prematurity (ROP) in neonates with refractory hypotension.

SEARCH METHODS

We searched the literature in January 2012, using the search strategy recommended by the Cochrane Neonatal Group. We searched electronic databases (CENTRAL (The Cochrane Library), MEDLINE, CINAHL, EMBASE), abstracts of the Pediatric Academic Societies, web sites for registered trials at www.clinicaltrials.gov and www.controlled-trials.com and in the reference list of identified articles.

SELECTION CRITERIA

Randomized or quasi-randomized trials evaluating vasopressin or its analogues, at any dosage or duration used as an adjunct to standard therapy (any combination of volume expansion, inotropic agents and corticosteroids) to treat refractory hypotension in neonates.

DATA COLLECTION AND ANALYSIS

We followed the standard methods of The Cochrane Collaboration for conducting a systematic review. Two review authors (BS and MP) independently assessed the titles and abstracts of studies identified by the search strategy for eligibility for inclusion. We obtained the full text version if eligibility could not be done reliably by title and abstract. We resolved any differences by mutual discussion. We designed electronic forms for trial inclusion/exclusion, data extraction, and for requesting additional published information from authors of the original reports.

MAIN RESULTS

Our search did not identify any completed or ongoing trials that met our inclusion criteria. Three studies that did not include neonates and one study where the objective was not to treat neonates with refractory hypotension were excluded.

AUTHORS' CONCLUSIONS

There is insufficient evidence to recommend or refute the use of vasopressin or its analogues in the treatment of refractory hypotension in neonates. Well-designed, adequately powered, randomized controlled studies are necessary to address efficacy, optimal dosing, safety and long-term neurodevelopmental and pulmonary outcomes. 

Vasopressin for the treatment of neonatal hypotension

Vasopressin (pitressin), also known as arginine vasopressin (AVP), is an antidiuretic hormone formed in the hypothalamus and secreted from the posterior pituitary gland. Various forms of exogenous vasopressin exist and have been used in neonates to treat conditions such as diabetes insipidus. Vasopressin has also been studied on a limited basis for use in the treatment of catecholamine-resistant hypotension in vasodilatory shock. Hypotension is a significant problem resulting in increased morbidity in preterm, septic, and postsurgical neonates. This article will discuss the role of vasopressin and its use as a therapeutic agent in the treatment of hypotension in the neonate.

Challenges in understanding the impact of blood pressure management on cerebral oxygenation in the preterm brain

Systemic hypotension in preterm infants has been related to increased mortality, cerebrovascular lesions, and neurodevelopmental morbidity. Treatment of hypotension with inotropic medications aims at preservation of end organ perfusion and oxygen delivery, especially the brain. The common inotropic medications in preterm infants include dopamine, dobutamine, adrenaline, with adjunctive use of corticosteroids in cases of refractory hypotension. Whether maintenance of mean arterial blood pressure (MAP) by use of inotropic medication is neuroprotective or not remains unclear. This review explores the different inotropic agents and their effects on perfusion and oxygenation in the preterm brain, in clinical studies as well as in animal models. Dopamine and adrenalin, because of their α-adrenergic vasoconstrictor actions, have raised concerns of reduction in cerebral blood flow (CBF). Several studies in hypotensive preterm infants have shown that dopamine elevates CBF together with increased MAP, in keeping with limited cerebro-autoregulation. Adrenaline is also effective in raising cerebral perfusion together with MAP in preterm infants. Experimental studies in immature animals show no cerebro-vasoconstrictive effects of dopamine or adrenaline, but demonstrate the consistent findings of increased cerebral perfusion and oxygenation with the use of dopamine, dobutamine, and adrenaline, alongside with raised MAP. Both clinical and animal studies report the transitory effects of adrenaline in increasing plasma lactate, and blood glucose, which might render its use as a 2nd line therapy. To investigate the cerebral effects of inotropic agents in long-term outcome in hypotensive preterm infants, carefully designed prospective research possibly including preterm infants with permissive hypotension is required. Preterm animal models would be useful in investigating the relationship between the physiological effects of inotropes and histopathology outcomes in the developing brain.

Permissive hypotension in extremely low birth weight infants (≤1000 gm)

PURPOSE

We performed this study to evaluate the safety of permissive hypotension management in extremely low birth weight infants (ELBWIs).

MATERIALS AND METHODS

Medical records of all inborn ELBWIs admitted to Samsung Medical Center from January 2004 to December 2008 were reviewed retrospectively. Of a total of 261 ELBWIs, 47 (18%) required treatment for hypotension (group T), 110 (42%) remained normotensive (group N), and 104 (40%) experienced more than one episode of hypotension without treatment (group P) during the first 72 hours of life. Treatment of hypotension included inotropic support and/or fluid loading.

RESULTS

Birth weight and Apgar scores were significantly lower in the T group than the other two groups. In the N group, the rate of pathologically confirmed maternal chorioamnionitis was significantly higher than other two groups, and the rate was higher in the P group than the T group. After adjusting for covariate factors, no significant differences in mortality and major morbidities were found between the N and P groups. However, the mortality rate and the incidence of intraventricular hemorrhage (≥stage 3) and bronchopulmonary dysplasia (≥moderate) were significantly higher in the T group than the other two groups. Long term neurodevelopmental outcomes were not significantly different between the N and P groups.

CONCLUSION

Close observation of hypotensive ELBWIs who showed good clinical perfusion signs without intervention allowed to avoid unnecessary medications and resulted in good neurological outcomes.

Time-course effect of a single dose of hydrocortisone for refractory hypotension in preterm infants

BACKGROUND

The aim of this study was to determine the time-course effect of a single dose of hydrocortisone (HC) on arterial blood pressure in extremely low gestational age newborns (ELGAN) with refractory hypotension during the first 3 days of life.

METHODS

We carried out a matched case-control study of a cohort of 116 infants born between 23 and 27 weeks' gestation at a tertiary center. Twelve infants (10%) were treated with HC for refractory hypotension (HC group). HC was administered at a dose of 2 mg/kg when mean arterial pressure (MAP) was below 30 mmHg (25 mmHg for infants <25 weeks of gestational age) despite the use of inotropes and volume expanders. Changes in the MAP after the HC administration were compared with those in the infants who were not treated with HC and matched for gestational age (Control group).

RESULTS

The mean MAP before administration of HC was significantly lower in the HC group than that in the control group (24.0 ± 3.2 vs 33.3 ± 4.8 mmHg; P < 0.01). The mean MAP in the HC group increased significantly at 2 h after HC treatment, and then reached levels comparable to those in the Control group at 5 h (31.3 ± 4.0 vs 33.9 ± 4.7 mmHg; P= 0.18), and remained at normal levels until 12 h after HC treatment.

CONCLUSION

A single dose of HC treatment induces a rapid and sustained improvement in blood pressure in ELGAN with refractory hypotension.

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.

A meta-analysis of dopamine use in hypotensive preterm infants: blood pressure and cerebral hemodynamics

OBJECTIVE

Dopamine administration results in variable effects on blood pressure in hypotensive preterm infants. The clinical benefits of dopamine administration in increasing cerebral blood flow (CBF) and reducing adverse neurological outcomes in hypotensive preterm neonates are unclear. The objective of this study was to examine the efficacy of dopamine for treatment of hypotension and investigate the changes in cerebral hemodynamics and central nervous system injury in hypotensive preterm infants following dopamine administration.

STUDY DESIGN

Standard meta-analytic techniques, including random and fixed effects models, were used to calculate combined effect size correlations and significance levels.

RESULT

Random effects meta-analysis found that dopamine increases mean arterial blood pressure (12 studies; N=163; r=0.88, 95% confidence interval (CI)=0.76 to 0.94) and systolic blood pressure (8 studies; N=142; r=0.81, 95% CI=0.42 to 0.94). For the increase in blood pressure, dopamine administration was associated with a significantly greater overall efficacy than dobutamine (seven studies; N=251; r=0.26; 95% CI=0.20 to 0.32), colloid (two studies; N=67; r=0.60; 95% CI=0.41 to 0.74) and hydrocortisone (one study; N=28; r=0.40; 95% CI=0.034 to 0.67). CBF increased following dopamine administration (five studies; N=75; r=0.36; 95% CI=-0.059 to 0.67) and the increase in CBF was greater in hypotensive than normotensive preterm infants (eight studies; N=153; r=0.16; 95% CI=-0.0080 to 0.32). There were no statistically significant differences in adverse neurological outcome between dopamine and dobutamine (three studies; N=118; r=-0.13; 95% CI=-0.31 to 0.059), epinephrine (two studies; N=46; r=0.06; 95% CI=-0.23 to 0.34), colloid (two studies; N=80; r=0.0070; 95% CI=-0.218 to 0.23) or hydrocortisone administration (one study; N=40; r=-0.10; 95% CI=-0.40 to 0.22).

CONCLUSION

Dopamine administration increases mean and systolic blood pressure in hypotensive preterm infants, and is more effective than dobutamine, colloid or hydrocortisone alone. Dopamine administration is associated with increased CBF, with greater increases in CBF in hypotensive than in normotensive preterm infants. Dopamine is not associated with a greater incidence of adverse effects than other therapies used to treat hypotension.

New NANN Practice Guideline: the management of hypotension in the very-low-birth-weight infant

The Management of Hypotension in the Very-Low-Birth-Weight Infant: Guideline for Practice, developed by Lyn Vargo, PhD, RN, NNP-BC, and Istvan Seri, MD, PhD, in 2011 under the auspices of the National Association of Neonatal Nurse Practitioners, focuses on the challenging topic of clinical management of systemic hypotension in the very low-birth-weight (VLBW) infant during the first 3 days of postnatal life. The recommendations and rationale in the excerpt below from the complete online publication are based on the best evidence available through both neonatal research and consultation of experts on the subject. They suggest a conservative, evidence-based treatment approach for the management of hypotension in the VLBW infant during the first 3 days of postnatal life that is logical, safe, and physiologically sound. The insufficient fund of knowledge on transitional cardiovascular physiology in general and pathophysiology in particular makes establishment of strict guidelines on the treatment of hypotension in VLBW neonates impossible. What becomes clear when presenting the evidence is how much more we need to know. Readers are strongly encouraged to refer to the complete text of the guideline, which has been endorsed by the American Academy of Pediatrics, for further understanding of this complex topic. The guideline is available free of charge at www.nann.org (click on Guidelines in the Education section).

A comparison of magnesium sulphate and sildenafil in the treatment of the newborns with persistent pulmonary hypertension: a randomized controlled trial

The aim of this prospective, randomized and controlled study was to compare the clinical efficacy of intravenous magnesium sulfate (MgSO₄) and oral sildenafil therapies with persistent pulmonary hypertension of the newborn. A total of 34 infants in the MgSO₄ group and 31 infants in the sildenafil group completed the study. The time to reach the adequate clinical response [defined as oxygen index (OI) level of <15, a pulmonary artery pressure of < 20 mmHg) was significantly shorter in the sildenafil group (p = 0.002). Duration of mechanical ventilation was longer and the number of the patients requiring inotropic support was higher in the MgSO₄ group (p = 0.001 and p = 0.002, respectively). Although among two groups the difference in OI > 5 as speculated in our hypothesis could only be found at 36 h of the treatment, sildenafil was more effective than MgSO₄ in the treatment of persistent pulmonary hypertension of the newborns with regard to time to adequate clinical response, duration of mechanical ventilation and support requirement with inotropic agents.

The impact of oral glutamine supplementation on the intestinal permeability and incidence of necrotizing enterocolitis/septicemia in premature neonates

OBJECTIVE

To examine the impact of oral glutamine (Gln) supplementation on gut integrity and on the incidence of necrotizing enterocolitis (NEC)/septicemia of premature neonates.

METHODS

Preterm neonates (n = 101, gestational age <34 weeks, birth weight <2000 g) were randomly allocated to receive from day 3 to day 30 postpartum, either oral Gln (0.3 g/kg/day, n = 51-Gln group) or placebo (caloreen-isocaloric, n = 50-control group). Intestinal permeability was determined from the urinary lactulose/mannitol recovery (L/M ratio) following their oral administration and assessed at three time points: day 2 (before first administration), day 7 and day 30 of life. The incidence of NEC and septicemia over the study period was also recorded.

RESULTS

A decrease of lactulose recovery at days 7 (p = 0.001) and 30 (p < 0.001) and a decrease of L/M ratio at day 7 (p = 0.002) were observed only in the Gln group. Lactulose recovery and L/M ratio at day 7 (p = 0.022 and p = 0.004, respectively), as well as lactulose recovery (p = 0.001), mannitol recovery (p = 0.042), and L/M ratio (p = 0.001) at day 30, were decreased in the Gln group as compared to controls. NEC and septicemia were lower in the Gln group at the end of the first week (p = 0.009 and p = 0.041, respectively) and up to the end of the study (p < 0.001 and p = 0.048, respectively).

CONCLUSION

Oral Gln administration may have beneficial effects on intestinal integrity and the overall incidence of NEC/septicemia in preterm infants.

Changes in skin and subcutaneous perfusion in very-low-birth-weight infants during the transitional period

BACKGROUND

Conventional parameters of circulation that are routinely used in neonatal intensive care units, including blood pressure, have been reported to be inadequate in improving prognosis of very-low-birth-weight (VLBW) infants. Recently, the importance of evaluating the blood flow to each organ, including both vital and nonvital organs, has been increasingly recognized.

OBJECTIVES

To study the changes in peripheral perfusion occurring in VLBW infants of less than 32 weeks' gestation during the extrauterine transitional period.

METHODS

In 32 VLBW infants of less than 32 weeks' gestation, forehead blood flow (FBF) and lower-limb blood flow (LBF) were measured for 48 h after birth using a novel laser Doppler flowmeter, and the indices of vascular resistance were estimated. Superior vena cava (SVC) blood flow was measured by echocardiography. Changes in these variables of circulation as well as the correlations were evaluated.

RESULTS

Both FBF and LBF significantly increased at 24 h, while the SVC flow remained unchanged over the same period. Both forehead and lower-limb vascular resistance indices significantly decreased at 24 h. LBF was negatively and positively correlated with estimated upper body vascular resistance and SVC flow, respectively.

CONCLUSIONS

The increase in the peripheral blood flow along with the decrease in the peripheral vascular resistance indices, without an increase in the systemic blood flow at 24 h of age, indicated vasodilation in skin and subcutaneous tissue during the transitional period in VLBW infants. FBF and LBF can be useful parameters as indicators of both peripheral and systemic circulation.

Hydrocortisone administration increases pulmonary artery pressure in asphyxiated newborn piglets reoxygenated with 100% oxygen

In severely asphyxiated neonates developing vasopressor-resistant shock, hydrocortisone is commonly used to improve perfusion. However, its acute haemodynamic effects in asphyxiated neonates are largely unknown. In a swine model of neonatal asphyxia, effects of hydrocortisone on systemic and pulmonary circulations were examined. Piglets (1-3d, 1.5-2.4kg) were acutely instrumented to measure heart rate, systemic and pulmonary artery pressures, and pulmonary artery flow. After 2h of normocapnic hypoxia, animals were resuscitated with 100% oxygen for 1h followed by 21% oxygen for 3h. Intravenous hydrocortisone (1mg/kg) or saline was given in a blinded, randomized fashion 2h after reoxygenation (n=6/group). Haemodynamic parameters, blood gases, plasma cortisol, as well as levels of endothelin-1, nitrite/nitrate, nitrotyrosine, matrix metalloproteinases-2 and -9 in the lung were analysed. Severe hypoxia caused metabolic acidosis (mean pH: 6.91-6.97, mean plasma lactate: 17.2-18.3mM), tachycardia and shock. Hydrocortisone did not affect systemic haemodynamics which recovered with reoxygenation, but it increased pulmonary artery pressure at 90-120min after administration (36±3 vs. 27±2 and 26±1mmHg for hypoxia-reoxygenation control and sham-operated piglets, respectively, P<0.05). In the lung tissue, hydrocortisone significantly increased endothelin-1 and nitrite/nitrate levels, but had no effect on nitrotyrosine. Further, it decreased lung matrix metalloproteinase-9, but not matrix metalloproteinase-2, activity, which were both elevated with hypoxia-reoxygenation. It is most likely that the increase in pulmonary artery pressure observed after hydrocortisone treatment was associated with increased endothelin-1 level in the lung. Our findings caution the use of hydrocortisone as a first-intention treatment of shock in asphyxiated neonates.

Management of hypotension in the very low-birth-weight infant during the golden hour

Primum non nocere, a saying in Latin that means "first, do no harm," is a phrase neonatal clinicians should keep in mind when initiating or suggesting treatment. In the "golden hour" of resuscitation of the very low-birth-weight infant, team members assess multiple parameters of the infant's vital signs, with a key one being that of the cardiovascular status, specifically blood pressure. Attempts to treat a number rather than after assessment and develop a sound plan of care based on findings, will affect both short- and long-term outcomes. By understanding what neonatal hypotension is and knowing when and how to treat it, the neonatal clinician honors this charge and can safely and effectively manage the very low-birth-weight infant with hypotension shortly after birth.

Agreement of invasive versus non-invasive blood pressure in preterm neonates is not dependent on birth weight or gestational age

PURPOSE

Blood pressure constitutes an important parameter in the assessment of the cardiovascular status in preterm infants. Invasive arterial blood pressure (IBP) is considered the 'gold-standard', but non-invasive blood pressure (NIBP) is used frequently in preterm infants. The aim of this prospective study was to compare mean IBP and mean NIBP arterial blood pressure measurements in three subsets of preterm infants (>1500 g; 1000-1500 g, and <1000 g, and >31 weeks, 28-31 weeks, and <28 weeks of gestation).

METHODS

Prospective, simultaneous assessment of both IBP and NIBP measurements in 50 preterm neonates at 6, 12, 18, 24 h after birth in a tertiary University centre.

RESULTS

Mean gestational age was 26.7 +/- 2.2 (24-32) in group I (n= 18), 29.6 +/- 2.0 (27-34) in group II (n= 19) and 32.2 +/- 1.9(30-36) weeks in group III (n= 13), respectively; mean birth weight was 777 +/- 161 (495-995), 1251 +/- 154 (1010-1490) and 2010 +/- 332 (1590-2550) g. Mean IBP and mean NIBP increased significantly during the first 24 h of life in all three sub-groups (P < 0.01); IBP and NIBP measurements were significantly correlated, and showed good agreement, irrespective of birth weight and gestational age.

CONCLUSIONS

Although IBP monitoring is considered the 'gold standard', NIBP values showed good agreement with those obtained invasively irrespective of gestational age and birth weight. We conclude that NIBP monitoring constitutes an important parameter in the assessment of the cardiovascular status even in extremely low birth weight infants.

How do pediatric anesthesiologists define intraoperative hypotension?

INTRODUCTION

Although blood pressure (BP) monitoring is a recommended standard of care by the ASA, and pediatric anesthesiologists routinely monitor the BP of their patients and when appropriate treat deviations from 'normal', there is no robust definition of hypotension in any of the pediatric anesthesia texts or journals. Consequently, what constitutes hypotension in pediatric anesthesia is currently unknown. We designed a questionnaire-based survey of pediatric anesthesiologists to determine the BP ranges and thresholds used to define intraoperative hypotension (IOH).

METHODS

Members of the Society of Pediatric Anesthesia (SPA) and the Association of Paediatric Anaesthetists (APA) of Great Britain and Ireland were contacted through e-mail to participate in this survey. We asked a few demographic questions and five questions about specific definitions of hypotension for different age groups of patients undergoing inguinal herniorraphy, a common pediatric surgical procedure.

RESULTS

The overall response rate was 56% (483/860), of which 76% were SPA members. Majority of the respondents (72%) work in academic institutions, while 8.9% work in institutions with fewer than 1000 annual pediatric surgical caseload. About 76% of respondents indicated that a 20-30% reduction in baseline systolic blood pressure (SBP) indicates significant hypotension in children under anesthesia. Most responders (86.7%) indicated that they use mean arterial pressure or SBP (72%) to define IOH. The mean SBP values for hypotension quoted by SPA members was about 5-7% lower across all pediatric age groups compared to values quoted by APA members (P = 0.001 for all age groups).

CONCLUSIONS

There is great variability in the BP parameters used and the threshold used for defining and treating IOH among pediatric anesthesiologists. The majority of respondents considered a 20-30% reduction from baseline in SBP as indicative of significant hypotension. Lack of a consensus definition for a common clinical condition like IOH could have implications for patient care as well as future clinical research.

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.

Hypoxia in the term newborn: part three--sepsis and hypotension, neurologic, metabolic and hematologic disorders

Causes of hypoxia and cyanosis in the term newborn can be found within all physiologic systems and take the form of hundreds of specific diagnoses. In the first and second parts of this series, a wide range of cardiac and pulmonary causes for newborn hypoxia and cyanosis have been examined. Because they are familiar, cardiac and pulmonary diagnoses often represent our reactionary opinions-the options that we first entertain even before a proper systematic approach to the infant has been taken. In this final of a three part series, neurologic, hematologic and metabolic disorders are explored as a cause for abnormal oxygenation, as well as sepsis and hypotension. It is within these final categories that we find many of the obscure possibilities for neonatal hypoxia-the diagnoses that often require rigorous testing, or more sophisticated laboratory interpretation. Without consideration of these elusive entities, however, appropriate treatment and referral will be unnecessarily delayed.