Surfactant inadvertent loss using feeding catheters or endotracheal tubes

Surfactant has been administered through endotracheal tubes and also under spontaneous breathing using feeding catheters. We asked if different tube diameters and temperature may affect the amount of surfactant effectively delivered to the lungs.

Bench study using high-accuracy, legal balance and tube/catheters of different diameters. We injected 200 mg of poractant alfa into the tubes followed by air boluses. Experiments were performed in triplicate, both at room temperature and at 37°C. Surfactant and phospholipid remaining in the tube were calculated.

Surfactant lost into thin catheters (11 ± 0.4%) was more than that in endotracheal tubes (2-mm diameter: 3.6 ± 1.4%; 2.5-mm diameter: 3.7 ± 0.2%; 3-mm diameter: 5.2 ± 0.4%; p < 0.001 at post hoc test in each comparison against the thin catheter). Similar findings were found at 37°C (2-mm tube: 3.4 ± 0.4%; 2.5-mm tube: 3.8 ± 0.2%; 3-mm tube: 3.6 ± 0.4%; feeding tube: 11.5 ± 0.6%; p < 0.001 as above). In terms of lost phospholipids, 23 ± 0.8 mg were lost in the feeding tubes; 7.2 ± 2.9 mg (2-mm diameter), 7.4 ± 0.4 mg (2.5-mm diameter), and 10.3 ± 0.9 mg (3-mm diameter) of phospholipids remained in endotracheal tubes (p < 0.001 in each comparison against the feeding tube).

Surfactant loss using thin catheters is around two to three times higher than using common endotracheal tubes; on average, 20 mg of phospholipids (11% of the administered dose) are lost. These data may be useful to refine surfactant dosing.