Trial of aerosolised surfactant for preterm infants with respiratory distress syndrome

Individualized aerosol medicine: Integrating device into the patient

Pulmonary drug delivery is complex due to several challenges including disease-, patient-, and clinicians-related factors. Although many inhaled medications are available in aerosol medicine, delivering aerosolized medications to patients requires effective disease management. There is a large gap in the knowledge of clinicians who select and provide instructions for the correct use of aerosol devices. Since improper device selection, incorrect inhaler technique, and poor patient adherence to prescribed medications may result in inadequate disease control, individualized aerosol medicine is essential for effective disease management and control. The components of individualized aerosol medicine include: (1) Selecting the right device, (2) Selecting the right interface, (3) Educating the patient effectively, and (4) Increasing patient adherence to therapy. This paper reviews each of these components and provides recommendations to integrate the device and interface into the patient for better clinical outcomes.

Surfactant delivery by aerosol inhalation - past, present, and future

Surfactant replacement therapy (SRT) by nebulization to spontaneously breathing patients has been regarded as the Holy Grail since surfactant deficiency was first identified as the cause for neonatal respiratory distress syndrome. It avoids neonatal endotracheal intubation, a procedure that is often difficult and occasionally harmful. Unapproved alternatives to endotracheal tube placement for liquid surfactant instillation, such as LISA (thin catheter intubation) and SALSA (supraglottic airway insertion) have significant merit but are still invasive, leaving nebulized SRT as the only truly non-invasive method. In the past 60 years, we have learned much about the potential - and limitations - of nebulized SRT. In this review, we examine the promises and pitfalls of nebulized SRT, discuss what we know about neonatal aerosol drug delivery and recap some of the most recent randomized clinical trials of nebulized SRT. We conclude with a discussion of what is known and the next steps needed if this type of SRT is to become a regular part of clinical care.

A randomized controlled trial of nebulized surfactant for the treatment of severe COVID-19 in adults (COVSurf trial)

SARS-CoV-2 directly targets alveolar epithelial cells and can lead to surfactant deficiency. Early reports suggested surfactant replacement may be effective in improving outcomes. The aim of the study to assess the feasibility and efficacy of nebulized surfactant in mechanically ventilated COVID-19 patients. Patients were randomly assigned to receive open-labelled bovine nebulized surfactant or control (ratio 3-surfactant: 2-control). This was an exploratory dose-response study starting with 1080 mg of surfactant delivered at 3 time points (0, 8 and 24 h). After completion of 10 patients, the dose was reduced to 540 mg, and the frequency of nebulization was increased to 5/6 time points (0, 12, 24, 36, 48, and an optional 72 h) on the advice of the Trial Steering Committee. The co-primary outcomes were improvement in oxygenation (change in PaO2/FiO2 ratio) and ventilation index at 48 h. 20 patients were recruited (12 surfactant and 8 controls). Demographic and clinical characteristics were similar between groups at presentation. Nebulized surfactant administration was feasible. There was no significant improvement in oxygenation at 48 h overall. There were also no differences in secondary outcomes or adverse events. Nebulized surfactant administration is feasible in mechanically ventilated patients with COVID-19 but did not improve measures of oxygenation or ventilation.

A multicentre neonatal interventional randomised controlled trial of nebulized surfactant for preterm infants with respiratory distress: Neo-INSPIRe trial protocol

INTRODUCTION

Respiratory distress syndrome in preterm infants is an important cause of morbidity and mortality. Less invasive methods of surfactant administration, along with the use of continuous positive airway pressure (CPAP), have improved outcomes of preterm infants. Aerosolized surfactant can be given without the need for airway instrumentation and may be employed in areas where these skills are scarce. Recent trials from high-resourced countries utilising aerosolized surfactant have had a low quality of evidence and varying outcomes.

METHODS AND ANALYSIS

The Neo-INSPIRe trial is an unblinded, multicentre, randomised trial of a novel aerosolized surfactant drug/device combination. Inclusion criteria include preterm infants of 27-34+6 weeks' gestational age who weigh 900-1999g and who require CPAP with a fraction of inspired oxygen (FiO2) of 0.25-0.35 in the first 2-24 h of age. Infants are randomised 1:1 to control (CPAP alone) or intervention (CPAP with aerosolized surfactant). The primary outcome is the need for intratracheal bolus surfactant instillation within 72 h of age. Secondary outcomes include the incidence of reaching failure criteria (persistent FiO2 of > 0.40, severe apnoea or severe work of breathing), the need for and duration of ventilation and respiratory support, bronchopulmonary dysplasia and selected co-morbidities of prematurity. Assuming a 40% relative risk reduction to reduce the proportion of infants requiring intratracheal bolus surfactant from 45 to 27%, the study will aim to enrol 232 infants for the study to have a power of 80% to detect a significant difference with a type 1 error of 0.05.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the relevant human research ethics committees at University of Cape Town (HREC 681/2022), University of the Witwatersrand HREC (221112) and Stellenbosch University (M23/02/004).

TRIAL REGISTRATION

PACTR202307490670785.

Pulmonary Surfactant in Adult ARDS: Current Perspectives and Future Directions

Acute respiratory distress syndrome (ARDS) is a major cause of hypoxemic respiratory failure in adults, leading to the requirement for mechanical ventilation and poorer outcomes. Dysregulated surfactant metabolism and function are characteristic of ARDS. A combination of alveolar epithelial damage leading to altered surfactant synthesis, secretion, and breakdown with increased functional inhibition from overt alveolar inflammation contributes to the clinical features of poor alveolar compliance and alveolar collapse. Quantitative and qualitative alterations in the bronchoalveolar lavage and tracheal aspirate surfactant composition contribute to ARDS pathogenesis. Compared to neonatal respiratory distress syndrome (nRDS), replacement studies of exogenous surfactants in adult ARDS suggest no survival benefit. However, these studies are limited by disease heterogeneity, variations in surfactant preparations, doses, and delivery methods. More importantly, the lack of mechanistic understanding of the exact reasons for dysregulated surfactant remains a significant issue. Moreover, studies suggest an extremely short half-life of replaced surfactant, implying increased catabolism. Refining surfactant preparations and delivery methods with additional co-interventions to counteract surfactant inhibition and degradation has the potential to enhance the biophysical characteristics of surfactant in vivo.

Aerosol delivery in models of pediatric high flow nasal oxygen and mechanical ventilation

BACKGROUND

Aerosol drug delivery during high flow nasal oxygen (HFNO) and invasive mechanical ventilation (IMV) are key respiratory care strategies available for the treatment of pediatric patients. We aimed to quantify the impact of different HFNO and IMV set-ups on tracheal drug delivery via a vibrating mesh nebuliser (VMN).

METHODS

Percent tracheal dose via VMN was quantified during HFNO therapy and IMV in a benchtop model of a 9-month-old infant. Under HFNO, 3 cannula sizes were used at 3 flow rate settings with the VMN placed at the dry side of the humidifier. Under IMV, tracheal dose when VMN was placed at the dry side of the humidifier, 15 cm from the wye and between the wye and endotracheal tube (ETT) was assessed. Salbutamol at 2.5 mg/2.5 ml (1 mg/ml) was used for each test (N = 5). The impact of VMN refill on circuit pressure under HFNO and IMV was also assessed.

RESULTS

Tracheal dose was highest during HFNO with the largest cannula size (OPT318) set to the lowest flow rate setting of 2 L/min (liter per minute) (5.80 ± 0.17%). Increasing flow rate reduced tracheal drug delivery for all cannulas. For IMV, VMN on the dry side of the humidifier and between the wye and ETT gave optimal drug delivery (4.49 ± 0.14% vs. 4.43 ± 0.26% respectively). VMN refill did not impact circuit pressure for either HFNO therapy or IMV.

CONCLUSIONS

Gas flow rate and cannula size during HFNO and VMN position during IMV has a significant effect on tracheal drug delivery in a pediatric setting.

Surfactant Replacement Therapy: What’s the New Future?

Surfactant replacement therapy (SRT) can be lifesaving for preterm babies with respiratory distress because of surfactant deficiency. Attempts have been made over the last two decades to make surfactant administration as smooth and as nontraumatic as possible. Lesser invasive techniques, such as less invasive surfactant administration, minimally invasive surfactant therapy, intrapartum pharyngeal surfactant therapy, and the laryngeal mask airway, are preferred over invasive techniques like intubate surfactant extubation to reduce trauma and peridosing adverse effects. However, at present, aerosolized surfactant (AS) via nebulization remains the only truly noninvasive method of SRT. Many animal and human studies have shown promising results with the use of AS with similar clinical effects to an instilled surfactant with greater safety potential. But still AS has not been adapted to routine neonatal care. There is still scope for studies to further strengthen the role of AS. Also, SRT is a constantly changing field with new innovations revolutionizing and replacing old techniques.

Aerosol Delivery of Lung Surfactant and Nasal CPAP in the Treatment of Neonatal Respiratory Distress Syndrome

After shifting away from invasive mechanical ventilation and intratracheal instillation of surfactant toward non-invasive ventilation with nasal CPAP and less invasive surfactant administration in order to prevent bronchopulmonary dysplasia in preterm infants with respiratory distress syndrome, fully non-invasive surfactant nebulization is the next Holy Grail in neonatology. Here we review the characteristics of animal-derived (clinical) and new advanced synthetic lung surfactants and improvements in nebulization technology required to secure optimal lung deposition and effectivity of non-invasive lung surfactant administration. Studies in surfactant-deficient animals and preterm infants have demonstrated the safety and potential of non-invasive surfactant administration, but also provide new directions for the development of synthetic lung surfactant destined for aerosol delivery, implementation of breath-actuated nebulization and optimization of nasal CPAP, nebulizer circuit and nasal interface. Surfactant nebulization may offer a truly non-invasive option for surfactant delivery to preterm infants in the near future.