Less invasive surfactant administration: best practices and unanswered questions

Abstract

Purpose of review: The purpose of this review is to describe current concepts in the field of Less Invasive Surfactant Administration (LISA). The use of continuous positive airway pressure (CPAP) has become standard for the treatment of premature infants with respiratory problems throughout the world. However, if CPAP fails, technologies like LISA are needed that can combine surfactant delivery and spontaneous breathing with the support of noninvasive modes of ventilation.

Recent findings: LISA with thin catheters has been in use in Germany for more than 15 years. In the last 5 years, there was substantial interest in this method around the world. Randomized studies and recent metaanalyses indicate that the LISA technique helps to avoid mechanical ventilation especially in emerging respiratory distress syndrome (RDS). LISA is also associated with improved outcomes of preterm infants, specifically in the prevention of bronchopulmonary dysplasia (BPD) and intracranial hemorrhage (ICH). By now, a variety of different LISA catheters, devices and techniques have been described. However, most of the technologies are still connected with the unpleasant experience of laryngoscopy for the affected infants, so that the search for even less invasive techniques, for example, surfactant application by nebulization, goes on.

Summary: Maintenance of spontaneous breathing with support by the LISA technique holds big promise in the care of preterm infants. Patient comfort and lower complication rates are strong arguments to further investigate and promote the LISA approach. Open questions include exact indications for different patient groups, the usefulness of devices/catheters that have recently been built for the LISA technique and -- perhaps most urgently -- the issue of analgesia/sedation during the procedure. Studies on long-term outcome after LISA are under way.

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FIGURE 1

Devices for surfactant instillation by the standard and the less invasive surfactant administration method. From left to right: endotracheal tube size 2.5 (outer diameter 4.1 mm, see also Fig. 2a), soft suction catheter 5 French (outer diameter: 1.7 mm see also Fig. 2b), stiffer straight catheter (Lisacath) (outer diameter 1.7 mm) and special device (Neofact) with 3.5 French (outer diameter: 1.2 mm) catheter that is sliding out from the tip. Lisacath and Neofact have special ‘softer’ tips to avoid injury.

FIGURE 2

(a) 2.5 Portex endotracheal tube inserted into to the larynx. (b) 5 French Vygon suction catheter inserted into the larynx. Note that the endotracheal tube virtually occludes the laryngeal entrance (a), whereas the vocal cords and even a lumen can be seen above the small diameter suction tube (b) that is used for the LISA procedure. The pictures were taken with a video larnygoscope (C-MAC, Karl Storz, Tuttlingen, Germany) in a mannequin (PAUL, Sim Characters, Vienna, Austria) that simulates the conditions in a 1000 g, 27 +3 weeks premature baby with a body length of 35 cm. The larynx in the model goes back to an anatomically correct 3D printed larynx based on real-life MRI of a preterm baby with a corresponding gestational age. LISA, less invasive surfactant administration.