Changes in hemodynamics after rescue surfactant administration

Surfactant and neonatal hemodynamics during the postnatal transition

Surfactant replacement therapy (SRT) has revolutionized the management of respiratory distress syndrome (RDS) in premature infants, leading to improved survival rates and decreased morbidity. SRT may, however, be associated with hemodynamic changes, which can have both positive and negative effects on the immature cardiovascular system, during the transitional adaptation from fetal to extrauterine environment. However, there is a relative paucity of evidence in this domain, with most of them derived from small heterogeneous observational studies providing conflicting results. In this review, we will discuss the hemodynamic changes that occur with surfactant administration during this vulnerable period, focusing on available evidence regarding changes in pulmonary and systemic blood flow, cerebral circulation and their clinical implications.

A novel delivery system for supraglottic atomization allows increased lung deposition rates of pulmonary surfactant in newborn piglets

BACKGROUND

Earlier attempts to deliver effective lung doses of surfactant by aerosolization were unsuccessful, mostly because of technical shortcomings. We aimed at quantifying the lung deposition of poractant alfa with a new supraglottic delivery system for surfactant atomization in an experimental neonatal model.

METHODS

The method involved six sedated 1-day-old piglets lying in the lateral decubitus, spontaneously breathing on nasal-mask continuous positive airway pressure (nCPAP). A pharyngeal cannula housing a multi-channel air-blasting atomization catheter was placed through the mouth with its tip above the glottis entrance. In all, 200 mg kg^-1 of a ^99mTc-surfactant mixture was atomized through the catheter synchronously with inspiration. Six intubated control piglets received an equal amount of intratracheally instilled ^99mTc-surfactant mixture. The percentage of the ^99mTc-surfactant mixture deposited in the lungs was estimated by scintigraphy.

RESULTS

Median (range) deposition in the lungs was 40% (24-68%) after atomization and 87% (55-95%) after instillation (p < 0.001). Overall, almost 80% of the deposited surfactant was in the dependent lung. Effective atomization time (atomizer on) was 28 (17-52) min, yielding an output rate of 0.1-0.2 mL min^-1.

CONCLUSIONS

Without endotracheal intubation, in spontaneously breathing newborn piglets, this new supraglottic atomizer delivery system attained a median lung deposition of 40% of the nominal dose of surfactant.

Cardiorespiratory Physiology following Minimally Invasive Surfactant Therapy in Preterm Infants

INTRODUCTION

Surfactant replacement therapy through the endotracheal tube has been shown to improve lung compliance and reduce pulmonary pressures. Minimally invasive surfactant therapy (MIST) combines the benefits of continuous positive airway pressure (CPAP) and surfactant for spontaneously breathing preterm infants. We aimed to characterize the haemodynamic changes accompanying the first dose of MIST in preterm infants.

METHODS

Poractant alfa (200 mg/kg) was administered as MIST while on CPAP support. Echocardiograms were performed before (T1) and 30 (T2) and 60 min (T3) after MIST to assess serial change.

RESULTS

Twenty infants (mean gestational age 29.5 ± 2.8 weeks, median birth weight 1,102 g, IQR 840-1,940) received MIST at a median age of 16 h (IQR 3-24). FiO2 decreased significantly at 30 min (0.41 ± 0.08 to 0.27 ± 0.03, p < 0.001). Significant changes were noted at T2 for ductal parameters (decreased % time right to left shunt: 25% [15-33] to 14.5% [6-22], p = 0.013). Reduced pulmonary vascular resistance (PVR; increased pulmonary artery time velocity ratio 0.23 ± 0.05 to 0.28 ± 0.04 ms, p = 0.004) and improved longitudinal (tricuspid annular plane systolic excursion 4.5 ± 0.8 to 5.3 ± 0.9 mm, p = 0.004) and global (fractional area change 25 ± 2.3 vs. 27 ± 2%, p = 0.002) ventricular function were noted.

CONCLUSIONS

This is the first study assessing cardiovascular adaptation to MIST, a procedure fast gaining acceptance in the neonatal community. Increased pulmonary blood flow is likely due to a combined effect of increased ductal flow, reduced PVR, and increased ventricular function.

The Neu-Prem Trial: Neuromonitoring of Brains of Infants Born Preterm During Resuscitation-A Prospective Observational Cohort Study

OBJECTIVE

To determine whether monitoring cerebral oxygen tissue saturation (StO₂) with near-infrared spectroscopy (NIRS) and brain activity with amplitude-integrated electroencephalography (aEEG) can predict infants at risk for intraventricular hemorrhage (IVH) and death in the first 72 hours of life.

STUDY DESIGN

A NIRS sensor and electroencephalography leads were placed on 127 newborns <32 weeks of gestational age at birth. Ten minutes of continuous NIRS and aEEG along with heart rate, peripheral arterial oxygen saturation, fraction of inspired oxygen, and mean airway pressure measurements were obtained in the delivery room. Once the infant was transferred to the neonatal intensive care unit, NIRS, aEEG, and vital signs were recorded until 72 hours of life. An ultrasound scan of the head was performed within the first 12 hours of life and again at 72 hours of life.

RESULTS

Thirteen of the infants developed any IVH or died; of these, 4 developed severe IVH (grade 3-4) within 72 hours. There were no differences in either cerebral StO₂ or aEEG in the infants with low-grade IVH. Infants who developed severe IVH or death had significantly lower cerebral StO₂ from 8 to 10 minutes of life.

CONCLUSIONS

aEEG was not predictive of IVH or death in the delivery room or in the neonatal intensive care unit. It may be possible to use NIRS in the delivery room to predict severe IVH and early death.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02605733.

Timing of umbilical cord clamping among infants born at 22 through 27 weeks' gestation

OBJECTIVE

To investigate the safety, feasibility and efficacy of delayed cord clamping (DCC) compared with immediate cord clamping (ICC) at delivery among infants born at 22 to 27 weeks' gestation.

STUDY DESIGN

This was a pilot, randomized, controlled trial in which women in labor with singleton pregnancies at 22 to 27 weeks' gestation were randomly assigned to ICC (cord clamped at 5 to 10 s) or DCC (30 to 45 s).

RESULTS

Forty mother-infant pairs were randomized. Infants in the ICC and DCC groups had mean gestational ages (GA) of 24.6 and 24.4 weeks, respectively. No differences were observed between the groups across all available safety measures, although infants in the DCC group had higher admission temperatures than infants in the ICC group (97.4 vs. 96.2 °F, P=0.04). During the first 24 h of life, blood pressures were lower in the ICC group than in the DCC group (P<0.05), despite a threefold greater incidence of treatment for hypotension (45% vs. 12%, P<0.01). Infants in the ICC group had increased numbers of red blood transfusions (in first 28 days of life) than infants in DCC group (4.1±3.9 vs. 2.8±2.2, P=0.04).

CONCLUSION

Among infants born at an average GA of 24 weeks', DCC appears safe, logistically feasible, and offers hematological and circulatory advantages compared with ICC. A more comprehensive appraisal of this practice is needed.

The effects of umbilical cord milking on hemodynamics and neonatal outcomes in premature neonates

OBJECTIVE

To determine whether umbilical cord milking (UCM) improves systemic blood flow and reduces neonatal morbidities compared with immediate cord clamping (ICC).

STUDY DESIGN

Women admitted to a tertiary care center and delivering before 32 weeks' gestation were randomized to receive UCM or ICC. Three blinded serial echocardiograms were performed in the first 2 days of the infant's life. The primary outcome was measured systemic blood flow (superior vena cava flow) at each time point.

RESULTS

Of the 60 neonates who were enrolled and randomized, 30 were assigned to cord milking and 30 to ICC. Neonates randomized to cord milking had greater measures of superior vena cava flow and right ventricular output in the first 6 hours and 30 hours of life. Neonates receiving UCM also had greater serum hemoglobin, received fewer blood transfusions, fewer days on oxygen therapy, and less frequent use of oxygen at 36 weeks' corrected postmenstrual age.

CONCLUSIONS

We demonstrate greater systemic blood flow with UCM in preterm neonates compared with ICC. Future large prospective trials are needed to determine whether UCM reduces intraventricular hemorrhage and other long-term morbidities.