High-frequency oscillatory ventilation does not decrease endothelin release in lung-lavaged rabbits

High-frequency oscillatory ventilation (HFO); has been shown to reduce lung injury and pulmonary arterial pressure (PAP). We hypothesized that HFO lea ds to decreased endothelin 1 (ET-1) and endothelin 3 (ET-3) release when co mpared to conventional mechanical ventilation (CMV) in lung-lavaged rabbits . Design: Prospective, randomized, controlled animal study. In 26 adult New Zealand White Rabbits ventilated by CMV or HFO under hypoxemic and normoxe mic conditions after lung lavage (CMV-hypo: n = 5; CMV-normo: n = 8; HFO-hy po: n = 7; HFO-normo: n = 6) we recorded systemic and PAP, measured blood g ases, ET-1 and ET-3 and calculated intrapulmonary venous admixture during a 4-h experiment. ET-1 was significantly increased after lavage (p < 0.05) w ith no further increase until the end of the experiment. Neither pulmonary arterial nor systemic arterial ET-1 differed between CMV and HFO or between hypoxemia and normoxemia. Systemic arterial ET-3, however, was significant ly higher in HFO-hypo than in the other two groups ventilated under normoxe mic conditions at the end of the experiment (HFO-hypo vs. CMV-normo, p < 0. 05; HFO-hypo vs. HFO-normo, p < 0.05). PAP showed a continuous increase in all groups (p < 0.05). We did not find any correlation between PAP and ET-1 or ET-3. Intrapulmonary venous admixture increased in animals ventilated u nder hypoxemic conditions, whereas it decreased after lung lavage in those ventilated under normoxemic conditions until the end of the experiment (HFO -normo, p < 0.05). Conclusions: This study suggests that HFO does not decre ase ET-1 and ET-3 release compared to CMV in lung-lavaged rabbits. Hypoxemi a, however, may increase ET-3 release from the lungs, leading to an increas ed intrapulmonary shunt.