Hemodynamic effects of periodic G(z) acceleration in meconium aspiration in pigs

The hemodynamic effects of periodic acceleration (pG(z)), induced in the sp inal axis with noninvasive motion ventilation (NIMV), were studied in a pig let model of pulmonary hypertension associated with meconium aspiration. An imals (n. = 12) were anesthetized, paralyzed, intubated, and supported by c onventional mechanical ventilation (CMV). Thirty minutes after tracheal ins tillation of meconium solution (6 ml/kg), either CMV (n = 6) was continued or NIMV (n = 6) was initiated. Changes in systemic and pulmonary hemodynami cs and arterial blood gases were tracked for 2 h after aspiration. Thermodi lution, cardiac output, and heart rate were not significantly different aft er meconium aspiration in the pG(z) group relative to the CMV controls. Aor tic pressure and systemic vascular resistance were significantly lower (sim ilar to 30%) after meconium aspiration in NIMV animals relative to CMV anim als. Pulmonary arterial pressure and pulmonary vascular resistance were als o significantly lower, by 100%, after aspiration of meconium in the NIMV an imals compared with the CMV controls. Meconium aspiration significantly dec reased total respiratory compliance by similar to 50% and increased total r espiratory resistance by similar to 100% in both CMV and NIMV animals, but such alterations did not differ between the two groups. Both CMV and NIMV s atisfactorily supported ventilation in these paralyzed animals. In conclusi on, NIMV through pG(z) in the spinal axis decreased systemic and pulmonary vascular resistance in piglets after meconium aspiration.