A Controlled Comparison of Two Different Calfactant Preparations in a Surfactant Deficient Lamb Model

Calfactant is an animal-derived surfactant, FDA-approved for endotracheal tube administration. Complications during surfactant administration may be related to the volume being delivered. We conducted a controlled comparison of calfactant against a more concentrated, lower volume calfactant. We compared the efficacy and complications of delivery of the two calfactant formulations to each other, and to no surfactant treatment, in the well-established preterm newborn lamb model of surfactant-deficient respiratory distress syndrome. After initial stabilization, a single dose of liquid calfactant or sham air instillation was given, and animals were maintained on mechanical ventilation for up to 6 hours. Reflux of surfactant into the endotracheal airway occurred in 83% of calfactant-treated lambs versus 33% of a more concentrated, lower volume calfactant-treated lambs. Lambs treated with a more concentrated, lower volume calfactant required less positive pressure breaths to clear refluxed surfactant (4 ± 2 versus 30 ± 8) and less time to deliver surfactant (70 ± 10 seconds, versus 130 ± 29 seconds). Ventilation and oxygenation improved significantly in surfactant-treated lambs, but not in controls. Four of six control lambs met adverse endpoint criteria prior to 6 hours, while surfactant-treated lambs remained stable up to 6 hours. We conclude that a more concentrated, lower volume calfactant has similar efficacy to calfactant but can be delivered more quickly and with less risk of complications.