Non-invasive ventilation and surfactant treatment as the primary mode of respiratory support in surfactant-deficient newborn piglets

Structural and haemodynamic evaluation of less invasive surfactant administration during nasal intermittent positive pressure ventilation in surfactant-deficient newborn piglets

The most recent approaches to the initial treatment of respiratory distress syndrome (RDS)- involve non-invasive ventilation (NIV) and less-invasive surfactant (SF) administration (LISA). Combining these techniques has been proven a useful treatment option for SF-deficient neonates. The objective of this study was to explore the impact on the brain (using cerebral near infrared spectroscopy, NIRS) of different LISA methods during NIV, using nasal intermittent positive pressure ventilation (NIPPV) for treating neonatal RDS. For this, we used five groups of spontaneously breathing newborn piglets (n = 6/group) with bronchoalveolar lavage (BAL)-induced respiratory distress which received NIPPV only (controls), poractant-alfa using the INSURE-like method (bolus delivery) followed by NIPPV, or poractant-alfa using one of three LISA devices, 1) a nasogastric tube (NT), 2) a vascular catheter (VC) or 3) the LISAcath® catheter. We assessed pulmonary, hemodynamic and cerebral effects, and performed histological analysis of lung and brain tissue. Following BALs, the piglets developed severe RDS (pH<7.2, PaCO2>70 mmHg, PaO2<70 mmHg, dynamic compliance<0.5 ml/cmH2O/kg at FiO2 = 1). Poractant-alfa administration using different LISA techniques during NIPPV was well tolerated and efficacious in newborn piglets. In our study, although all groups showed normal physiological ranges of total lung injury score and biochemical lung analysis, VC and LISAcath® catheters were associated with better values of lung compliance and lower values of lung damage than NIPPV, NT or INSURE-like methods. Moreover, neither of the SF administration methods used (LISA or INSURE-like) had a significant impact on the histological neonatal brain injury score. Of note, the LISAcath® has been recently withdrawn from the market.

Surfactant nebulization therapy during NIPPV ventilation in surfactant-deficient newborn piglets

BACKGROUND

In recent years, nasal intermittent positive pressure ventilation (NIPPV) has been growing in popularity as a form of noninvasive ventilation for respiratory support in the initial treatment of neonates with surfactant (SF) deficiency. The combination of this type of ventilation with noninvasive SF administration (by nebulization) is an attractive treatment option for respiratory distress syndrome (RDS)-associated pathophysiology of the neonatal lungs. In this study, we aimed to test the tolerability and efficacy of SF nebulization during NIPPV for the treatment of neonatal RDS.

METHODS

Spontaneously-breathing newborn piglets (n = 6/group) with bronchoalveolar lavage (BAL)-induced RDS were assigned to receive during NIPPV (180 min): poractant alfa (400 mg/kg) via an investigational customized vibrating-membrane nebulizer (eFlow-Neos) or poractant alfa (200 mg/kg) as a bolus using the Insure method or no surfactant (controls).

MEASUREMENT AND RESULTS

We assessed pulmonary, hemodynamic and cerebral effects and performed histological analysis of lung and brain tissue. After repeated BAL, newborn piglets developed severe RDS (F_iO2 : 1, pH < 7.2, P_aCO2  > 70 mmHg, P_aO2 < 70 mmHg, C_dyn  < 0.5 ml/cmH₂ O/kg). In both SF-treated groups, we observed rapid improvement in pulmonary status and also similar hemodynamic, cerebral behavior, and lung and brain injury scores.

CONCLUSION

Our results in newborn piglets with severe BAL-induced RDS show the administration of nebulized poractant alfa using the eFlow-Neos nebulizer during NIPPV to be well tolerated and efficacious, suggesting that this noninvasive SF administration option should be explored further.

Nebulized Poractant Alfa Reduces the Risk of Respiratory Failure at 72 Hours in Spontaneously Breathing Surfactant-Deficient Newborn Piglets

Supplemental Digital Content is available in the text.

We have setup for the first time a long-term (72 hr) respiratory distress syndrome model in spontaneously breathing surfactant-deficient newborn piglets to investigate the continuous positive airway pressure failure rate with nebulized poractant alfa compared with that with the intubation surfactant extubation technique or continuous positive airway pressure only.

Dose-Response Study on Surfactant Nebulization Therapy During Nasal Continuous Positive Airway Pressure Ventilation in Spontaneously Breathing Surfactant-Deficient Newborn Piglets

OBJECTIVES

The current clinical treatment of neonates with respiratory distress syndrome includes endotracheal intubation and intratracheal instillation of exogenous surfactant. Nebulization of surfactant offers an attractive alternative. The aims of this study were to test nebulization as a noninvasive method of administering surfactant and determine the optimal dose for the treatment of respiratory distress syndrome-associated pathophysiology of the neonatal lungs.

DESIGN

Prospective, randomized, animal model study.

SETTING

An experimental laboratory.

SUBJECTS

Thirty-six newborn piglets.

INTERVENTIONS

Different doses (100, 200, 400, and 600 mg/kg) of poractant alfa were administered via a vibrating membrane nebulizer (eFlow-Neos; Pari Pharma GmbH, Starnberg, Germany) or a bolus administration using the intubation-surfactant-extubation (Insure) technique (200 mg/kg) to spontaneously breathing newborn piglets (n = 6/group) with bronchoalveolar lavage-induced respiratory distress syndrome during nasal continuous positive airway pressure (180 min).

MEASUREMENTS AND MAIN RESULTS

Pulmonary, hemodynamic, and cerebral effects were assessed. Histologic analysis of lung and brain tissue was also performed. After repeated bronchoalveolar lavage, newborn piglets developed severe respiratory distress syndrome. Rapid improvement in pulmonary status was observed in the Insure group, whereas a dose-response effect was observed in nebulized surfactant groups. Nebulized poractant alfa was more effective at doses higher than 100 mg/kg and was associated with similar pulmonary, hemodynamic, and cerebral behavior to that in the Insure group, but improved lung injury scores.

CONCLUSIONS

In newborn piglets with severe bronchoalveolar lavage-induced respiratory distress syndrome, our results demonstrate that the administration of nebulized poractant alfa using an investigational customized eFlow-Neos nebulizer is an effective and safe noninvasive surfactant administration technique.

Cerebral oxygenation associated with INSURE versus LISA procedures in surfactant-deficient newborn piglet RDS model

BACKGROUND

Nasal continuous-positive airway pressure (nCPAP) with the INSURE (INtubation-SURfactant-Extubation) or LISA (Less-Invasive Surfactant Administration) procedures are increasingly being chosen as the initial treatment for neonates with surfactant deficiency. Our objective was to compare the effects on cerebral oxygenation of different methods for surfactant administration: INSURE and LISA, using a nasogastric tube (NT) or a LISAcath® catheter, in spontaneously breathing SF-deficient newborn piglets.

METHODS

Eighteen newborn piglets with SF-deficient lung injury produced by repetitive bronchoalveolar lavages were randomly assigned to INSURE, LISA-NT, or LISAcath® groups. We assessed pulmonary (gas exchange, lung mechanics, lung histology) and hemodynamic (mean arterial blood pressure, heart rate) changes, cerebral oxygenation (cTOI) and cerebral fractional tissue extraction (cFTOE), with near-infrared spectroscopy, carotid blood flow and brain histology.

RESULTS

SF-deficient piglets developed respiratory distress (F_iO2  = 1, pH <7.2, P_aCO2 >70 mmHg, P_aO2 <70 mmHg, C_dyn <0.5 mL/cmH₂ O/kg). Rapid improvements in pulmonary status were observed in all surfactant-treated groups without hemodynamic alterations. In the INSURE group, a transient decrease in cTOI occurred during and immediately after surfactant administration, while cTOI only decreased during surfactant administration in the LISA-NT group and did not change significantly in the LISAcath® group. Brain injury scores were low in all surfactant-treated groups.

CONCLUSION

In spontaneously breathing SF-deficient newborn piglets, short-lasting decreases in cerebral oxygenation are associated with surfactant administration by the INSURE method or LISA using an NT, while no cerebral oxygenation changes occurred with LISA using a LISAcath®. Notably, none of treatments studied seems to have a negative impact on the neonatal brain.