EFFICACY OF INHALED NITRIC OXIDE (iNO) AND ALKALOSIS DURING PARTIAL LIQUID VENTILATION IN PULMONARY HYPERTENSION. † 1495

We investigated the efficacy of the prevailing therapies for pulmonary hypertension when combined with partial liquid ventilation (PLV). 36 piglets(age: 7-24 days) were randomly allocated to conventional ventilation (IPPV) or PLV (initial perfluorocarbon volume: 30ml/kg; Rimar 101™) at an Fi0₂of 0.4. Pulmonary vascular resistance (PVR) was then increased from 51 ± 4 to 189 ± 10 mm Hg/L/ min/kg by infusion of a thromboxane(TX) mimetic (U46,619: 0.09 ± 0.01 μg/kg/min). Animals were sequentially tested under: eucapnea (EU) → iNO 5ppm →iNO 40 ppm→eucapnea → respiratory alkalosis (ALK) (pH=7.59 ± 0.01)→ ALK with iNO(40 ppm). Results: Table below compares changes between PLV and IPPV for each sequence (mean ± s.e.m). The changes in PVR and oxygenation (Aa0₂: alveolar-arterial 0₂ gradient) are shown as% change from the previous eucapneic state. Cardiac output (C.O.) is in ml/min/kg and lung compliance (Cdyn) in ml/cm H₂O/kg. Conclusions: prior to TX, the perfluorocarbon caused a density associated cardiovascular depression of moderate degree. However this did not prevent iNO and ALK to be at least as efficient as during IPPV. For both modes of ventilation, iNO and ALK had an additive effect. PLV preserved lung compliance more efficiently than IPPV and could therefore be a more effective mode of treatment in pulmonary hypertension associated with lung injury.

Table 1