Introduction: Accurate measurement of airway pressures (Paw) are crucial during mechanical ventilation. Intratracheal pulmonary ventilation(ITPV) utilizes a reverse thruster device to deliver a continuous flow of gas at the level of the carina, thereby generating a different carinal Paw than conventional ventilation (CV). This study compares the proximal and carinal Paw during CV and ITPV, in both an artificial lung an in a rabbit model.
Method: Proximal and carinal pressures during CV and ITPV were recorded in an artificial lung (BIOTEK) using rates of 30 and 90 breaths per minute with flow rates of 3 and 6 liters per minute. In this in vitro model, ITPV compared with CV, significantly reduced the level of pressure at the carina in a dry state. Humidification, however, prevented consistent carinal Paw measurements because of moisture buildup inside the pressure line. In the rabbit model this problem was resolved by adding a small bias flow into the pressure monitoring line. The ITPV tip was placed approximately 1 cm above the end of the endotracheal tube. After establishing normocapnea, respiratory parameters, i.e. flow, frequency, and inspiratory time were held constant during both CV and ITPV. Each rabbit was then tested during 1 hour on CV, followed by 1 hour of ITPV, and returned to CV with a rate of 10 breaths per minute. The data were analyzed by repeated measures ANOVA followed by Dunnett multiple comparisons test.
Results: The small bias flow allowed accurate carinal Paw measurements during ITPV in rabbits. The data indicate significant pressure difference at the proximal level between CV and ITPV, but no significant changes at the carinal level. Part of the pressure results are presented below. The gas exchange values will be presented elsewhere.
Conclusion: Carinal Paw can be accurately measured during ITPV. Carinal Paw values are lower than proximal Paw during both ITPV and CV. During ITPV and CV, the carinal Paw values are a more accurate estimate of the alveolar pressure. Table
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(Spon by: Fima Lifshitz) Supported by Hudson RCI and Cook Critical Care.
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Bolivar, J., Hultquist, K., Hon, E. et al. Carinal and Proximal Pressures During Intratracheal Pulmonary Ventilation in an Artificial Lung and in Rabbits † 183. Pediatr Res 43 (Suppl 4), 34 (1998). https://doi.org/10.1203/00006450-199804001-00204
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DOI: https://doi.org/10.1203/00006450-199804001-00204
