ARTIFICIAL SURFACTANT FOR THERAPY IN HYDROCARBON-INDUCED LUNG INJURY IN SHEEP

Objective: To document the effect of administering artificial surfacta nt into the trachea, either by instillation or aerosolization, on acut e lung injury experimentally induced with kerosene in sheep. Design: R andomized, prospective, controlled study, Setting: Research laboratory , Subjects: Sheep (n = 24), weighing 8.5 to 25.2 kg (average 16.6). In terventions: In anesthetized, tracheally intubated sheep with pulmonar y and femoral artery catheters inserted, lung injury was induced by in stilling kerosene (0.3 mL/kg) into the trachea. After 15 mins of spont aneous breathing, mechanical ventilation was instituted with a uniform Fro, and a tidal volume of 10 mL/kg, Sheep were then assigned randoml y to one of four regimens as follows: exogenous surfactant or saline ( 5 mL/kg each) was administered as a bolus intratracheally or by aeroso lization for 6 hrs, Measurements and Main Results: Arterial and mixed venous blood gases, pH, airway pressure, and static respiratory system compliance were measured and compared between aerosol saline and aero sol 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 w as determined for each animal, and group rank sums of hourly rates of change were compared. For static respiratory system compliance, the sl ope of the pressure-volume curve with volumes of 100, 200, 300, 400, a nd 500 mt was computed for each animal at baseline and at 3 and 6 hrs after kerosene instillation, Group rank sums for static respiratory sy stem compliance at 3 and 6 hrs were compared, Also, the 3- and 6-hr st atic respiratory system compliance values at each of the volumes were compared. With saline, six of eight sheep died; with surfactant, no sh eep died (p=.001), When compared with saline at 15 mins, 1 hr, and 6 h rs after kerosene instillation, surfactant, regardless of whether admi nistered by aerosol or bolus, significantly increased rate of change o f arterial oxygen saturation, mixed venous oxygen saturation, and Po-2 . Conclusions: In the present animal study, artificial surfactant was an effective treatment for hydrocarbon aspiration, Aerosolized surfact ant achieved results similar to instilled surfactant but at a lower to tal dose.