Lavage administration of dilute surfactant in a piglet model of meconium aspiration

Abstract

Maldistribution of exogenous surfactant may preclude any clinical response in acute lung injury associated with surfactant dysfunction. Our previous studies have shown the effectiveness of surfactant lavage after homogenous lung injury. The present study utilizes a histologically confirmed non-homogeneous lung injury model induced by saline lung-lavage followed by meconium injected into a mainstem bronchus. Piglets were then treated with Infasurf or Exosurf by lavage (I-LAVAGE, n = 7; E-LAVAGE, n = 5) or bolus (I-BOLUS, n = 8; E-BOLUS, n = 5), or went untreated (CONTROL, n = 4). Lavage administration utilized a dilute surfactant (35 ml/kg; 4 mg phospholipid/ml) instilled into the lung, followed by gravity drainage. The retained doses of the respective surfactant in the lavage and bolus groups were similar. Results showed that the surfactant distribution was more uniform in the lavage groups compared to the bolus groups. Significant and consistent increases in PaO2 were observed in the lavage groups compared to the bolus groups and the controls. PaO2 (mmHg) at 240 min posttreatment: I-LAVAGE = 297 +/- 54, E-LAVAGE = 280 +/- 57; I-BOLUS = 139 +/- 31; E-BOLUS = 152 +/- 29; C = 119 +/- 73 (mean +/- SEM). Other improved pulmonary function parameters favored lavage administration. We conclude that better surfactant distribution achieved by lavage administration can be more effective than bolus administration in this type of non-homogeneous lung injury.

Fig. 1

PaO₂ in control and surfactant-treated groups. Surfactant was administered immediately after Sick measurement. *Different from sick within the group; ^†different from control; ^‡different from respective bolus group.

Fig. 2

Quasi-static pressure-volume curves for control and surfactant-treated groups. Error bars deleted for clarity. The lower portion of the curves represents the inflation component while the upper portion represents the deflation component.

Fig. 3

Surfactant distribution as measured by colored microspheres. Upper panel showing pooled data from lavage groups (5 animals; n = 265 lung pieces); lower panel showing pooled data from bolus groups (4 animals; n = 212 lung pieces). Microsphere count in each lung piece expressed as ratio of actual/expected in increment intervals of 0.2 on the x-axis. The vertical line on the graph represents the mean for the data.

Fig. 4

Photomicrograph of a representative section of the lung showing adjacent areas of relatively normal-appearing architecture and signs of severe inflammation with neutrophil, infiltration.