Effects of volume-targeted synchronized intermittent mandatory ventilation on spontaneous episodes of hypoxemia in preterm infants.
BACKGROUND
Hypoxemic episodes in ventilated preterm infants are frequently caused by reduced ventilation due to a decrease in lung volume and acute worsening of respiratory mechanics.


OBJECTIVE
To compare the efficacy of conventional time-cycled, pressure-limited flow synchronized intermittent mandatory ventilation (SIMV) and volume-targeted SIMV (VT-SIMV) in reducing the frequency and severity of these episodes.


METHODS
SIMV and VT-SIMV were compared in preterm infants with frequent spontaneous episodes of hypoxemia. VT-SIMV was provided with the Draeger Babylog 8000plus ventilator in volume-guarantee mode.


RESULTS
In all, 32 infants (birth weight 668 +/- 126 g, gestational age 24.8 +/- 1.1 weeks, age 37.5 +/- 17.3 days) were studied during 2-hour periods of SIMV and VT-SIMV in random sequence. In an initial phase, a group of 12 infants was supported during VT-SIMV with a target tidal volume of 4.5 ml/kg (VT-SIMV 4.5). A planned interim analysis did not show differences in frequency and duration of hypoxemia between VT-SIMV 4.5 and SIMV, and the initial phase was stopped. In a second phase of the study, 20 infants were studied while supported with a target tidal volume of 6.0 ml/kg during VT-SIMV (VT-SIMV 6.0). In the second phase of the study, the frequency of the hypoxemic episodes did not change but the mean episode duration was shorter during VT-SIMV compared to SIMV. The proportion of mechanical breaths with small tidal volumes (< or =3 ml/kg) was reduced during VT-SIMV 6.0 versus SIMV, while the peak inspiratory pressure and mean airway pressure were increased.


CONCLUSIONS
VT-SIMV did not reduce the frequency of hypoxemic episodes, but VT-SIMV 6.0 was effective in reducing the duration of the hypoxemic episodes.
Polimeni
Valentina
V
Division of Newborn Medicine, Department of Pediatrics, University of Miami School of Medicine, Miami, Fla. 3301, USA.
Claure
Nelson
N
D'Ugard
Carmen
C
Bancalari
Eduardo
E
D005865:Gestational Age; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology / Q000209:etiology / Q000628:therapy*; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000628:therapy*; D012121:Respiration, Artificial / Q000379:methods*; D013990:Tidal Volume