Alveolar recruitment promotes homogeneous surfactant distribution in a piglet model of lung injury

Uneven distribution of exogenous surfactant contributes to a poor clinical response In animal models or respiratory distress syndrome. Alveolar recrui tment at the time of surfactant administration may lead to more homogeneous distribution within the lungs and result in a superior clinical response. To investigate the effects of three different volume recruitment maneuvers on gas exchange, lung function, and homogeneity of surfactant distribution, we studied 35 newborn piglets made surfactant deficient by repeated airway lavage with warm saline. Volume recruitment was achieved by either a tempo ral increase in tidal volume or an increase in end-expiratory pressure duri ng surfactant administration, yielding an increase in dynamic compliance of the respiratory system of 77% in the first group and an increase in functi onal residual capacity of 108% in the second group. A third group of piglet s (all n = 7) received a combination of both volume recruitment maneuvers, with increases in dynamic compliance of the respiratory system of 100% and in functional residual capacity of 192%. Those animals subjected to increas ed tidal volume showed an improved surfactant response in terms of oxygenat ion, ventilation, lung volumes, lung mechanics, and homogeneity of surfacta nt distribution. Increased end-expiratory volume augmented the surfactant e ffect only to some extent. The combination of both volume recruitment maneu vers, however, Uneven distribution of exogenous surfactant contributes to a needed lung volumes beyond total lung capacity (approximately 56 mL/kg), t hus probably inducing early sequelae of ventilator-induced lung injury. We conclude that volume recruitment by means of increased tidal volumes at the time of surfactant administration leads to a superior surfactant effect ow ing to more homogeneous surfactant distribution within a collapsed lung.