End-Tidal CO2as a Function of Tidal Volume in Mechanically Ventilated Infants

Abstract

Objective: To test the hypothesis that end-tidal CO₂ (PETCO₂) varies with tidal volume (Vt) in preterm infants. Design: Intervention study, nonrandomized trial. Setting: Neonatal ICU, regional referral center. Subjects: 29 preterm infants 790 to 2135 g in weight requiring mechanical ventilation studied on 73 occasions. Intervention: Measurement of PETCO₂ during variations of Vt. Measurement: Statistical correlation of PETCO₂ to Vt. Result: PETCO₂ is minimal when Vt is either too low or too high. Conclusion: Vt, through its effect on dead space/Vt (Vd/Vt) ratios and arterial-alveolar CO₂ differences, has a significant effect on PETCO₂. Observation of PETCO₂ across a range of Vt can be used to select an appropriate Vt for preterm infants requiring mechanical ventilation.