Terbutaline lessens protein fluxes across the alveolo-capillary barrier during high-volume ventilation.

OBJECTIVE

To evaluate whether a beta2-adrenergic agonist may reduce acute alveolo-capillary barrier alterations during high-volume ventilation.

DESIGN

Experimental study.

SETTING

Animal research laboratory.

SUBJECTS

A total of 48 male Wistar rats.

INTERVENTIONS

A zone of alveolar flooding was produced by liquid instillation in a distal airway. Proteins in the instilled solution were traced with 99mTc-albumin. 111In, which binds to transferrin, was injected into the systemic circulation. Terbutaline was administered in the instilled solution or intra-peritoneally. Conventional ventilation was applied for 30 min followed by different ventilation strategies for 90 min: conventional ventilation, high-volume ventilation with or without 6 cmH2O PEEP.

MEASUREMENTS AND MAIN RESULTS

Protein fluxes across the alveolar and microvascular barriers were evaluated by scintigraphy. High-volume ventilation resulted in immediate leakage of 99mTc-albumin from alveolar spaces and increased pulmonary uptake of systemic 111In-transferrin. Terbutaline in the instilled solution and PEEP lessened alveolar 99mTc-albumin leakage and pulmonary 111In-transferrin uptake due to high-volume ventilation, whereas terbutaline given intra-peritoneally only lessened 111In-transferrin uptake. Terbutaline in the instilled solution also lessened the increase in lung wet-to-dry weight ratio due to high-volume ventilation.

CONCLUSIONS

Terbutaline reduces protein fluxes across the alveolar epithelial and pulmonary microvascular barriers during high-volume ventilation in vivo. The route of administration may be important.