COMPUTER-CONTROLLED MINUTE VENTILATION IN PRETERM INFANTS UNDERGOING MECHANICAL VENTILATION

Introduction: Computer-controlled minute ventilation (CCMV) continuous ly adjusts the ventilator rate to changes in spontaneous respiratory d rive and pulmonary mechanics to maintain a preset total minute ventila tion. Hypothesis: We hypothesized that CCMV would maintain ventilation and oxygenation with fewer mechanical breaths than conventional inter mittent mandatory ventilation in very low birth weight infants. Method s: Very low birth weight infants in clinically stable condition who we re undergoing mechanical ventilation were enrolled. The number of mech anical breaths, total and mechanical expiratory minute ventilation, me an airway pressure, oxygen hemoglobin saturation by pulse oximetry, an d transcutaneous partial carbon dioxide and partial oxygen tensions we re obtained during intermittent mandatory ventilation and CCMV (45 to 60 minutes) and compared by paired t test. Results: Fifteen infants we re studied. Birth weight (median, range) was 700 gm (550 to 1205 gm), gestational age 26 weeks (23 to 34 weeks), age 21 days (3 to 50 days). When switched from intermittent mandatory ventilation to CCMV the num ber of mechanical breaths was reduced (15 +/- 2.8 to 8.6 +/- 2.9 breat hs per minute, p < 0.001), leading to lower airway pressure (3.97 +/- 1.00 to 3.45 +/- 1.00 cm H2O, p < 0.001) and lower expiratory minute v entilation generated by the mechanical ventilator (116 +/- 31 to 65 +/ - 28 ml/min per kilogram, p < 0.001), while total expiratory minute ve ntilation remained unchanged. Mean transcutaneous partial carbon dioxi de and oxygen tensions, oxygen hemoglobin saturation, and the time spe nt within different oxygen hemoglobin saturation ranges did not differ between both ventilatory modes. Conclusion: CCMV maintained adequate ventilation and oxygenation with lower mechanical ventilatory support than IMV. CCMV may reduce barotrauma and chronic lung disease during l ong-term use.