Randomized controlled trial of volume-targeted synchronized ventilation and conventional intermittent mandatory ventilation following initial exogenous surfactant therapy

We set out to evaluate the impact of volume-targeted synchronized ventilati on and conventional intermittent mandatory ventilation (IMV) on the early p hysiologic response to surfactant replacement therapy in neonates with resp iratory distress syndrome (RDS). We hypothesized that volume-targeted, pati ent-triggered synchronized ventilation would stabilize minute ventilation a t a lower respiratory rate than that seen during volume-targeted IMV, and t hat synchronization would improve oxygenation and decrease variation in mea sured tidal volume (V-t). This was a prospective, randomized study of 30 ho spitalized neonates with RDS. Infants were randomly assigned to volume-targ eted ventilation using IMV (n = 10), synchronized IMV (SIMV; n = 10), or as sist/control ventilation (A/C; n = 10) after meeting eligibility requiremen ts and before initial surfactant treatment. Following measurements of arter ial blood gases and cardiovascular and respiratory parameters, infants rece ived surfactant. Infants were studied for 6 hr following surfactant treatme nt. Infants assigned to each mode of ventilation had similar birth weight, gest ational age, and Apgar scores at birth, and similar oxygenation indices at randomization. Three patients were eliminated from final data analysis beca use of exclusionary conditions unknown at randomization. Oxygenation improv ed significantly following surfactant therapy in all groups by 1 hr after s urfactant treatment (P < 0.05). No further improvements occurred with time. Total respiratory rate was lowest (P < 0.05) and variation in tidal volume (V-t) was least in the AIC group (P < 0.05). Minute ventilation (V-t), del ivered airway pressures, respiratory system mechanics, and hemodynamic para meters were similar in all groups. We conclude that volume-targeted A/C ventilation resulted in more consisten t tidal volumes at lower total respiratory rates than IMV or SIMV. Oxygenat ion and lung mechanics were not altered by synchronization, possibly due to the volume-targeting strategy. Of the modes studied, A/C, a fully-synchron ized mode, may be the most efficient method of mechanical ventilator suppor t in neonates receiving surfactant for treatment of RDS. (C) 2000 Wiley-Lis s. Inc.