2011 OPEN FORUM Abstracts
EFFECTS OF HFOV VENTILATORY PARAMETERS UPON THE LUNG HEMODYNAMICS IN RAT HEART AND LUNG DISSECTION.
Karel Roubik1, Vladimir Zabrodsky2; 1Dep. of Biomedical Technology, CTU in Prague, Fac. of Biomedical Engineering, Kladno, Czech Republic; 2Dep. of Anesthesia and CCM, Charles University, Faculty Thomayer Hospital, Prague, Czech Republic
Background: Inflation of alveoli during mechanical ventilation causes stress to the lung tissue with the blood capillaries and thereby ventilation affects pulmonary perfusion. Specific pulmonary hemodynamic effects are associated with HFOV. The aim of the study is to investigate effects of HFOV ventilatory parameters upon the pulmonary perfusion resistance of a lung and heart dissection. Methods: The study was approved by the Institutional review board for the care of laboratory animals of the 1st Faculty of Medicine, Charles University in Prague. Eight female Wistar rats (230-270 g) were used. Heart and lung dissection was hung in a rigid heated chamber and ventilated with air containing 5% of CO2 in order to keep the original bloodstream tonus. Pulmonary artery and left atrium were cannulated with input and output perfusion catheters leading from a linear or peristaltic pump into the heated reservoir of the perfusion solution (heparinized saline-albumin colloid solution). Ventilation was conducted with physiologic MAP (7.2 cm H2O) and physiologic VT values (2.1 mL at 2 Hz, 1.5 mL at 6 Hz, 1.1 mL at 10 Hz and 0.7 mL at 20 Hz), followed by ventilation with MAP increased by 90% and then with normal MAP and VT increased by 75%. Perfusion resistance Rp was calculated from perfusion pressure recorded in the input perfusion catheter during the constant perfusion flow rate of 10 mL/min from the linear pump. Two-tailed Student's t-test was used for evaluation of differences in Rp. Results: Results are presented in Fig. 1. Perfusion resistance is independent on ventilatory frequency and independent on changes in tidal volume. An increase in MAP increases Rp significantly. Conclusion: MAP is the only HFOV ventilatory parameter affecting lung perfusion resistance significantly in the heart and lung dissection model. Acknowledgment: Supported by research project MSM 6840770012.
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