Artificial surfactant for therapy in hydrocarbon-induced lung injury in sheep

To document the effect of administering artificial surfactant into the trachea, either by instillation or aerosolization, on acute lung injury experimentally induced with kerosene in sheep.

Randomized, prospective, controlled study.

Research laboratory.

Sheep (n = 24), weighing 8.5 to 25.2 kg (average 16.6).

In anesthetized, tracheally intubated sheep with pulmonary and femoral artery catheters inserted, lung injury was induced by instilling kerosene (0.3 mL/kg) into the trachea. After 15 mins of spontaneous breathing, mechanical ventilation was instituted with a uniform F10(2) and a tidal volume of 10 mL/kg. Sheep were then assigned randomly to one of four regimens as follows: exogenous surfactant or saline (5 mL/kg each) was administered as a bolus intratracheally or by aerosolization for 6 hrs.

Arterial and mixed venous blood gases, pH, airway pressure, and static respiratory system compliance were measured and compared between aerosol saline and aerosol surfactant and between bolus saline and bolus surfactant. For all variables except static respiratory system compliance, the hourly rate of change from 15 mins, 1 hr, and 6 hrs after kerosene instillation was determined for each animal, and group rank sums of hourly rates of change were compared. For static respiratory system compliance, the slope of the pressure-volume curve with volumes of 100, 200, 300, 400, and 500 mL was computed for each animal at baseline and at 3 and 6 hrs after kerosene instillation. Group rank sums for static respiratory system compliance at 3 and 6 hrs were compared. Also, the 3- and 6-hr static respiratory system compliance values at each of the volumes were compared. With saline, six of eight sheep died; with surfactant, no sheep died (p = .001). When compared with saline at 15 mins, 1 hr, and 6 hrs after kerosene instillation, surfactant, regardless of whether administered by aerosol or bolus, significantly increased rate of change of arterial oxygen saturation, mixed venous oxygen saturation, and PO2.

In the present animal study, artificial surfactant was an effective treatment for hydrocarbon aspiration. Aerosolized surfactant achieved results similar to instilled surfactant but at a lower total dose.