文本框: CHANGES IN CEREBRAL OXYGENATION AND HEMODYNAMICS DURING 2 DIFFERENT MODES OF HYPOXEMIA Liem KD, Kollée LAA, Hopman JCW, Oeseburg B* Department of Pediatrics and Physiology*, University Medical Centre Nijmegen, The Netherlands Objective: To compare the changes in cerebral oxygenation and hemodynamics during 2 different modes of induced hypoxemia in piglets. Methods: 12 piglets were anesthetized and ventilated. Hypoxemia was induced for 60 min (saO2 80%): in group A (n=6) by repeated lung lavage with saline and in group B (n=6) by lowering the FiO2. Concentration changes (in mmol/100 g) of oxyhemoglobin (ΔcO2Hb), deoxyhemoglobin (ΔcHHb) and total hemoglobin (ΔctHb) in brain were continuously measured with near infrared spectrophotometry. ΔcO2Hb & ΔcHHb reflect changes in cerebral O2 supply; ΔctHb reflects changes in cerebral blood volume. Changes in common carotid artery blood flow (Qcar in mL/min), mean arterial blood pressure (MABP), saO2 and paCO2 were also recorded. Results: Changes (mean ± SD) as compared to normoxia are shown in the table (* = significant changes, # = different from group A). Group A Group B time 15 min 60 min 15 min 60 min DcO2HbDcHHbDctHbDQcar -0.86 ± 0.46* 0.68 ± 0.33* -0.18 ± 0.34 1.50 ± 9.30 -0.91 ± 0.38* 0.56 ± 0.34* -0.35 ± 0.45 12.98 ± 17.90 -1.10 ± 0.30* 1.54 ± 0.32*# 0.43 ± 0.30*# 7.82 ± 5.33*# -1.01 ± 0.41* 1.52 ± 0.43*# 0.51 ± 0.42*# 11.77 ± 6.39*# No significant differences in MABP and saO2 between both groups. paCO2 at 60 min was higher in group A (50 ± 6 vs 36 ± 2 mm Hg). Conclusions: Despite hypercapnia, Qcar and cerebral blood volume did not increase after hypoxemia induced by lung lavage. The cause is unclear, but probably related to the lung lavage procedure. This aspect should be taken into account when using this model to investigate of the effect of pulmonary disease on cerebral hemodynamics. 1917