Background Minimal invasive surfactant therapy (MIST) is associated with a diminished need for mechanical ventilation. Insufficient insight exists in predictive success factors.

Aim Defining success factors for MIST.

Methods From 2011–2013 preterm infants admitted to the NICU with respiratory distress and radiographically established IRDS with FiO2 <0,4 were included for MIST procedure with surfactant (Survantaâ, 100 mg/kg) during nCPAP/nIPPV support. Therapeutic success was defined as decreased need for oxygenation without endotracheal ventilation support for 24 h. Patient characteristics were noted; including stress, defined as clinical discomfort and/or tachycardia, as well as procedure related desaturation (minimum 80%, < 30 seconds) bradycardia and complications (tracheal injury, pneumothorax or lung haemorrhage).

Results 40 neonates (GA 24⁺²–37⁺¹ weeks [30 weeks], birth weight 600–3330 gram [1375 gram], IRDS grade I-III) were eligible. In 38 patients MIST was performed (2/40 were nonetheless intubated due to unrest). Tube insertion caused bradycardia with spontaneous recovery in one patient. Surfactant administration caused desaturation with spontaneous recovery in all patients and apnea in one patient. There were no complications. Therapeutic success was reached in 24/38 (63,2%) patients. In 6/24 (25%) respiratory adjustments were necessary; increasing PEEP in 2/24, starting nIPPV in 4/24. Causes for intubation 14/38 (27,8%) were rebound IRDS (6/14), sepsis (5/14) and insufficient drive to breath 2/14. Gestational age, birth weight, FiO2/IRDS degree, timing of MIST and gastric tube route (nasal/oral) were not correlated with success.

Conclusion Success factors for MIST are a calm patient, an adequate drive to breathe and the absence of sepsis.