Validity of Biomarkers of Early Circulatory Impairment to Predict Outcome: A Retrospective Analysis

Cerebral near-infrared spectroscopy guided neonatal intensive care management for the preterm infant

Infants requiring admission to the neonatal intensive care unit (NICU) are particularly vulnerable to developing brain injury. The severity of the underlying clinical conditions and the complexity of care call for continuous, cot-side, non-invasive monitoring tools. Near-infrared spectroscopy (NIRS) measures the regional tissue oxygen saturation of hemoglobin (rStO2) and provides continuous information on the net-result of several factors. Cerebral rStO2 correlates with echocardiography-derived measures of blood flow. Cerebral fractional tissue oxygen extraction provides information on the balance between oxygen supply and demand and can be continuously derived from the combined use of cerebral rStO2 and arterial oxygen saturation. Information on cerebral blood flow autoregulatory capacity can be obtained from combining cerebral rStO2 and invasive blood pressure monitoring by appropriate software. Cerebral rStO2 provides real-time, end-organ information on perfusion-oxygenation, and when interpreted in the clinical context based on pathophysiological principles may be used as a help to guide interventions in the NICU. In this review we will discuss how to optimize NIRS monitoring for application in the NICU, with a particular focus on the preterm infant. IMPACT: Near-infrared spectroscopy (NIRS) provides cot-side, real-time information on blood and oxygen supply to the brain. Therefore, it is a valuable tool to better understand the pathophysiology underlaying disease processes. Current evidence suggests that NIRS-guided treatment in extremely preterm infants during transitional circulation does not improve clinical outcomes. Specific training is needed to maximize potential performance. Pathophysiological interpretation of cerebral NIRS data in the given clinical context may help in decision-making. Appropriate use of this monitoring technique, interpreted concurrently with other routine parameters, is a potential clinical tool to guide interventions in the NICU setting.

Cardiorespiratory interactions during the transitional period in extremely preterm infants: a narrative review

We aimed to review the physiology and evidence behind cardiorespiratory interactions during the transitional circulation of extremely preterm infants with fragile physiology and to propose a framework for future research. Cord clamping strategies have a great impact on initial haemodynamic changes, and appropriate transition can be facilitated by establishing spontaneous ventilation before cord clamping. Mechanical ventilation modifies preterm transitional haemodynamics, with positive pressure ventilation affecting the right and left heart loading conditions. Pulmonary vascular resistances can be minimized by ventilating with optimal lung volumes at functional residual capacity, and other pulmonary vasodilator treatments such as inhaled nitric oxide can be used to improve ventilation/perfusion mismatch. Different cardiovascular drugs can be used to provide support during transition in this population, and it is important to understand both their cardiovascular and respiratory effects, in order to provide adequate support to vulnerable preterm infants and improve outcomes. Current available non-invasive bedside tools, such as near-infrared spectroscopy, targeted neonatal echocardiography, or lung ultrasound offer the opportunity to precisely monitor cardiorespiratory interactions in preterm infants. More research is needed in this field using precision medicine to strengthen the benefits and avoid the harms associated to early neonatal interventions. IMPACT: In extremely preterm infants, haemodynamic and respiratory transitions are deeply interconnected, and their changes have a key impact in the establishment of lung aireation and postnatal circulation. We describe how mechanical ventilation modifies heart loading conditions and pulmonary vascular resistances in preterm patients, and how hemodynamic interventions such as cord clamping strategies or cardiovascular drugs affect the infant respiratory status. Current available non-invasive bedside tools can help monitor cardiorespiratory interactions in preterm infants. We highlight the areas of research in which precision medicine can help strengthen the benefits and avoid the harms associated to early neonatal interventions.

Predicting the effectiveness of drugs used for treating cardiovascular conditions in newborn infants

BACKGROUND

Cardiovascular support (CVS) treatment failure (TF) is associated with a poor prognosis in preterm infants.

METHODS

Medical charts of infants with a birth weight <1500 g who received either dopamine (Dp) or dobutamine (Db), were reviewed. Treatment response (TR) occurred if blood pressure increased >3rd centile for gestational age or superior vena cava flow was maintained >55 ml/kg/min, with decreased lactate or less negative base excess, without additional CVS. A predictive model of Dp and Db on TR was designed and the impact of TR on survival was analyzed.

RESULTS

Sixty-six infants (median gestational age 27.3 weeks, median birth weight 864 g) received Dp (n = 44) or Db (n = 22). TR occurred in 59% of the cases treated with Dp and 31% with Db, p = 0.04. Machine learning identified a model that correctly labeled Db response in 90% of the cases and Dp response in 61.4%. Sixteen infants died (9% of the TR group, 39% of the TF group; p = 0.004). Brain or gut morbidity-free survival was observed in 52% vs 30% in the TR and TF groups, respectively (p = 0.08).

CONCLUSIONS

New predictive models can anticipate Db but not Dp effectiveness in preterm infants. These algorithms may help the clinicians in the decision-making process.

IMPACT

Failure of cardiovascular support treatment increases the risk of mortality in very low birth weight infants. A predictive model built with machine learning techniques can help anticipate treatment response to dobutamine with high accuracy. Predictive models based on artificial intelligence may guide the clinicians in the decision-making process.

Randomised trial of dobutamine versus placebo for low superior vena cava flow in preterm infants: Long-term neurodevelopmental outcome

AIM

Although circulatory impairment during the transitional circulation associates morbidity and mortality, its treatment remains controversial. In a pilot trial on circulatory impairment defined as low superior vena cava (SVC) flow, dobutamine (Db) versus placebo (PL) showed a trend towards improved short-term outcomes. The purpose of this study was to report on the long-term outcome of the infants who were observed for SVC flow patterns.

METHODS

Among the 126 infants <31 weeks of gestation prospectively scanned from birth, 28 presented low SVC flow within the first 24 h after birth and received Db (n = 16) or PL (n = 12). Follow-up of survivors included motor assessment and Bayley Scales II or III at 2 years, and the Reynolds Intellectual Assessment Scale at 6 years. Neurodevelopmental impairment (NDI) was defined as: cerebral palsy (Gross Motor Function Classification System ≥ level 2), or a cognitive function score < -2 standard deviations; or moderate or severe hearing or visual impairment. Db group, PL group and normal-flow group were compared.

RESULTS

Eighteen infants died (Db: 5; PL: 2; normal flow group: 11, P = 0.1). Follow-up in survivors was accomplished in 80% and 55% of the cohort at 2 years and 6 years, respectively. No significant difference in the combined outcome (mortality or NDI) was found between the groups (42% Db, 36% PL, 30% normal flow group).

CONCLUSIONS

This exploratory analysis did not show any differences in the long-term outcome of infants according to SVC flow patterns or its treatment early after birth.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

What Inotrope and Why?

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