Introduction: No single treatment is consistently effective in infants with persistent pulmonary hypertension associated to MAS. We hypothesized that PLV could improve pulmonary gas exchange without impairing cardiovascular function. Aim: To evaluate the effects of perfluorocarbon (FC-75) PLV on gas exchange and cardiovascular profile in newborn lambs with experimental MAS. Subjects: 18 newborn lambs, <6 days of age (4.8±1.1 Kg) were randomly assigned to three groups (n=6) and managed for three hours. Methods: The animals were anesthetized, instrumented, and given 3-5 mL/Kg of 25% human meconium. Then, eMAS lambs were kept on IMV without further intervention. Those in iNO, and PLV groups were exposed to 20 ppm inhaled NO (iNO) or received 30 mL/Kg of PFC, respectively. Hearth rate, systemic and pulmonary arterial pressures (SAP and PAP), pH, blood gases, cardiac output (CO) and pulmonary mechanics were measured. Results: After meconium instillation, lambs developed respiratory failure (PaO2 <80 and PaCO2 >100 mmHg), pulmonary hypertension (PAP >30 mmHg) and decrease compliance (<0.5 mL/cmH2O/Kg). These values did not change in eMAS group. iNO produced an immediate but transient response (PaO2=128±53 and PaCO2=55±20 mmHg, PAP=25±5 mmHg). In PLV group, PaO2 >200 and PaCO2<40 mmHg were maintained, and compliance increased to 1.5 mL/cmH2O/Kg. Heart rate, SAP, CO, and PAP remained stable, in contrast to the downward (SAP, CO, and PAP) and upward (heart rate) trend seen in other groups. Conclusion: In eMAS, PLV improved pulmonary gas exchange without adversely affecting cardiovascular function. PLV with PFC might be a good alternative strategy in MAS.
