Abstract
RRV has been used to reduce PaCO2 in infants with persistent fetal circulation. RRV produces AO in the rabbit lung (time constant (τ) similar to infants). We hypothesized that AO could be reduced if the PEEP in the trachea (PEEPT) was controlled during RRV. We studied 10 rabbits measuring tracheal airway pressure, functional residual capacity (FRC) PaO2 and PaCO2 at ventilator (Baby Bird®) rates of 30, 60, 90 and 120 BPM white: 1) controlling ventilator PEEP (PEEPV) at 2 cm H2O then 2) controlling PEEPT at 2 cm H2O. Peak inspiratory pressure was held constant (15 cm H2O) as was inspiratory:expiratory time (1:2) at rates of 60, 90 ahd 120 BPM. To control PEEPT we lowered PEEPv to 1.2, 1.1 and 0.5 cm H2O. As rates were increased, controlling PEEPT resulted in significant decreases in mean airway pressure (Paw) (by 0.0±.0(SE), 0.4±.1, 0.5±.1 and 1.0±.2 cm H2O) and FRC (14±1, 15±1, 17±2, 21±2 ml/kg when PEEPV was 2 cm H2O vs. 14±1, 14±1, 15±1, 16±2 ml/kg when PEEPT was 2 cm H2O) (p<0.01). When rate was increased from 30 to 60 BPM, PaO2 increased significantly from 68±4 to 78±5 mm Hg when PEEPV was 2 cm H2O, then increased to 79±6 mm Hg when PEEPT was 2 cm H2O; PaCO2 decreased from 26±2 to 20±2 mm Hg when PEEPV was 2 cm H2O then decreased to 18±2 mm Hg when PEEPT was 2 cm H2O. Further increases in rate did not lead to significant changes in PaO2 or PaCO2 in either part of the study. We conclude: controlling PEEPT during RRV of lungs with normal τ results in decreased Paw, eliminates AO and blood gases comparable to those obtained when PEEPV is controlled.
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Gonzalez, F., Richardson, P. CONTROLLING ALVEOLAR OVERDISTENTION (AO) DURING RAPID RATE VENTILATION (RRV). Pediatr Res 18 (Suppl 4), 392 (1984). https://doi.org/10.1203/00006450-198404001-01796
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DOI: https://doi.org/10.1203/00006450-198404001-01796