IMPROVED OXYGENATION DURING SYNCHRONIZED INTERMITTENT MANDATORY VENTILATION IN NEONATES WITH RESPIRATORY-DISTRESS SYNDROME - A RANDOMIZED, CROSSOVER STUDY

In a randomized, crossover study, we compared arterial partial pressur e of oxygen and of carbon dioxide between consecutive periods of conve ntional and synchronized intermittent mandatory ventilation (SIMV). We studied spontaneously breathing infants with an endotracheal tube in place. The infants were <12 hours of age, had a diagnosis of respirato ry distress syndrome, and had an arterial/alveolar oxygen ratio of <0. 25. The int ants had a mean birth weight of 1077 gm and gestational ag e of 28 weeks. The mean rate of asynchrony on intermittent mandatory v entilation (IMV) was 52% (range, 36% to 76%), and on SIMV was <1%. Inf ants were randomly assigned to IMV or SIMV as their initial ventilator mode and underwent ventilation for four 15-minute periods, and crosse d over to the alternate mode after each period. Ventilator settings an d the fraction of inspired oxygen were not changed between modes. At t he end of each period, arterial blood gas measurements were obtained; 26 paired comparisons were made between modes. The mean arterial parti al pressure of oxygen was significantly higher during SIMV than during IMV (mean, 61.5 vs 53.3 mm Hg; p <0.01), The mean arterial partial pr essure of carbon dioxide was slightly lower during SIMV than during IM V (mean, 42.7 vs 41.3 mm Hg; p <0.05). The improvement in oxygenation demonstrated with SIMV may allow a reduction in ventilator pressure or oxygen exposure in this group of infants, who are at risk of having c omplications of ventilation.