Cerebral hemodynamics after exogenous surfactant administration for respiratory distress syndrome in piglet model

Do Different Amounts of Exogenous Surfactant Differently Influence Cerebrovascular Instability in a Consecutive Group of Preterm Babies? Preliminary Results from a Single-Center Experience

BACKGROUND

Thirty years ago, the first attempt by Saliba and colleagues was made to reduce the negative effects (hypercarbia) of exogenous surfactant (ES) by slowing its administration. Sixteen years later, we observed the first less invasive surfactant administration (LISA) attempt by Kribs and colleagues. Many studies, since that time, have tried to minimize the invasiveness of ES and subsequent cerebral blood flow perturbations through studies using near-infrared spectroscopy (NIRS). We sought to address this medical challenge by identifying a less problematic modality of ES administration by delivering multiple aliquots of ES instead of a single one, as typically performed. The aim of this study was to test the hypothesis that a different way of administering ES using more aliquots could be a safe alternative that should be assessed in further studies.

METHODS

Patients between 26 + 0 and 35 + 6 weeks of gestational age (GA) requiring ES administration were enrolled (April 2023-February 2024). Differently fractioned doses were delivered according to an arbitrary standard dosage (0.3 mL per aliquot in babies < 29 weeks; 0.6 mL in babies ≥ 29 weeks), while NIRS and transcutaneous CO2 (tCO2) monitoring were always performed. ES's effectiveness was assessed based on the reduction in the Oxygen Saturation Index (OSI) after administration. Persistent desaturation, bradycardia, and airway obstruction were defined as adverse effects and used to evaluate safety during ES administration, as well as variability in NIRS-rSO2 values and tCO2.

RESULTS

Twenty-four patients were enrolled with a median GA of 29 weeks (IQR 4.5) and BW of 1223 ± 560 g. In addition, 50% of the cohort received fewer than three aliquots, whereas the other 50% received more than three. Monitoring was started before the procedure and continued 30' after the last ES aliquot administration. The variability in NIRS-SpO2 values was significantly higher in the group (p = 0.007) with a lower number of aliquots administered. Similarly, increased NIRS-rSO2 values (p = 0.003) and increased tCO2 levels (p = 0.005) were observed in infants who underwent an ES split after the administration of a low number of aliquots.

CONCLUSIONS

Our data obtained from the group with > 3 fractionated doses of ES seem to justify the preparation of a more robust study, as the combination of reduced NIRS variability and reduced tCO2 maximum levels is consistent with more stable cerebral blood flow during the challenging time of ES administration.

The combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome increases the risk of intraventricular hemorrhage in preterm neonates

OBJECTIVE

To evaluate the impact of combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome (RDS) on the development of intraventricular hemorrhage (IVH) in preterm neonates.

METHODS

This retrospective cohort study includes 207 consecutive preterm births (24.0-33.0 weeks of gestation). Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. According to McMenamin's classification, IVH was defined as grade II or higher when detected by neurosonography within the first weeks of life.

RESULTS

(1) IVH was diagnosed in 6.8% (14/207) of neonates in the study population; (2) IVH was frequent among newborns exposed to intra-amniotic inflammation when followed by postnatal RDS [33% (6/18)]. The frequency of IVH was 7% (8/115) among neonates exposed to either of these conditions - intra-amniotic inflammation or RDS - and 0% (0/64) among those who were not exposed to these conditions; and (3) Neonates exposed to intra-amniotic inflammation and postnatal RDS had a significantly higher risk of IVH than those with only intra-amniotic inflammation [odds ratio (OR) 4.6, 95% confidence interval (CI) 1.1-19.3] and those with RDS alone (OR 5.6, 95% CI 1.0-30.9), after adjusting for gestational age.

CONCLUSION

The combined exposure to intra-amniotic inflammation and postnatal RDS markedly increased the risk of IVH in preterm neonates.

Effect of surfactant and partial liquid ventilation treatment on gas exchange and lung mechanics in immature lambs: influence of gestational age

Objectives

Surfactant (SF) and partial liquid ventilation (PLV) improve gas exchange and lung mechanics in neonatal RDS. However, variations in the effects of SF and PLV with degree of lung immaturity have not been thoroughly explored.

Setting

Experimental Neonatal Respiratory Physiology Research Unit, Cruces University Hospital.

Design

Prospective, randomized study using sealed envelopes.

Subjects

36 preterm lambs were exposed (at 125 or 133-days of gestational age) by laparotomy and intubated. Catheters were placed in the jugular vein and carotid artery.

Interventions

All the lambs were assigned to one of three subgroups given: 20 mL/Kg perfluorocarbon and managed with partial liquid ventilation (PLV), surfactant (Curosurf®, 200 mg/kg) or (3) no pulmonary treatment (Controls) for 3 h.

Measurements and Main Results

Cardiovascular parameters, blood gases and pulmonary mechanics were measured. In 125-day gestation lambs, SF treatment partially improved gas exchange and lung mechanics, while PLV produced significant rapid improvements in these parameters. In 133-day lambs, treatments with SF or PLV achieved similarly good responses. Neither surfactant nor PLV significantly affected the cardiovascular parameters.

Conclusion

SF therapy response was more effective in the older gestational age group whereas the effectiveness of PLV therapy was not gestational age dependent.

Cerebral hemodynamic change and intraventricular hemorrhage in very low birth weight infants with patent ductus arteriosus

The aims of this study were to assess the hemodynamics of the cerebral arteries and intraventricular hemorrhage in very-low-birthweight (VLBW) infants with and without patent ductus arteriosus (PDA) by cranial Doppler sonography. VLBW infants with significant PDA were recruited into the study (sPDA) group. Arterial blood gas analysis and complete blood counts were done near the time of the cranial sonography examination. Mechanical ventilator settings and daily fluid intake were recorded. The cranial Doppler sonographic examinations were repeated after PDA closure by indomethacin therapy and/or surgical ligation. A total of 40 preterm infants fulfilled the criteria of the study group. Another 37 preterm infants were recruited into a control group. Mean birth weight and gestational age did not differ significantly between the two groups. Differences in heart rate, blood pH, pCO2, pO2, use of surfactant therapy, mean airway pressure, ventilation index and FiO2 were statistically significant. In the sPDA group before closure of the PDA, the left atrial diameter/aorta diameter ratio demonstrated a positive relationship with resistance index (RI) and an inverse relationship with end diastolic velocities (Vd). After closure of the PDA, these changes neared those of the control group. The overall incidence of intraventricular hemorrhage (IVH) was higher in the sPDA than in the control group. There was no statistical difference in the grading and severity of IVH between the two groups. However, all preterm infants with severe IVH were found in the sPDA group, and their RIs were all higher than 0.80. Cranial Doppler sonography can be a useful tool to evaluate cerebral hemodynamic changes in VLBW infants with sPDA. Increased RI and decreased Vd of the cerebral artery may indicate a probable sPDA, and normalization of the RI and Vd may suggest closure of the sPDA.

Acute side effects of surfactant treatment

There is increasing evidence from studies on animals and humans that surfactant administration may have a great impact on cerebral perfusion. These effects may result from direct pulmonary or hemodynamic changes (or a combination of both), but may also be due to rapid alterations of blood gases. Type of surfactant and mode of administration seem to play an important role. Results from the pertinent literature are summarised with a special emphasis on how to avoid potentially harmful side effects of surfactant therapy in preterm infants.