1. Pattern of inspiratory gas delivery affects CO2 elimination in health and after acute lung injury.
- Author
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Åström, Elisabet, Uttman, Leif, Niklason, Lisbet, Aboab, Jerome, Brochard, Laurent, and Jonson, Björn
- Subjects
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SWINE , *MECHANICAL ventilators , *LUNG injuries , *GAS distribution , *CROSSOVER trials - Abstract
To avoid ventilator induced lung injury, tidal volume should be low in acute lung injury (ALI). Reducing dead space may be useful, for example by using a pattern of inspiration that prolongs the time available for gas distribution and diffusion within the respiratory zone, the mean distribution time (MDT). A study was conducted to investigate how MDT affects CO2 elimination in pigs at health and after ALI. Randomised crossover study in the animal laboratory of Lund University Biomedical Center. Healthy pigs and pigs with ALI, caused by surfactant perturbation and lung-damaging ventilation were ventilated with a computer-controlled ventilator. With this device each breath could be tailored with respect to insufflation time and pause time ( T I and T P) as well as flow shape (square, increasing or decreasing flow). The single-breath test for CO2 allowed analysis of the volume of expired CO2 and the volume of CO2 re-inspired from Y-piece and tubes. With a long MDT caused by long T I or T P, the expired volume of CO2 increased markedly in accordance with the MDT concept in both healthy and ALI pigs. High initial inspiratory flow caused by a short T I or decreasing flow increased the re-inspired volume of CO2. Arterial CO2 increased during a longer period of short MDT and decreased again when MDT was prolonged. CO2 elimination can be enhanced by a pattern of ventilation that prolongs MDT. Positive effects of prolonged MDT caused by short T I and decreasing flow were attenuated by high initial inspiratory flow. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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