| Objective: The present study was to observe the changes of neutrophils in pulmonary arterial blood and the respiratory function and to research the effect of activated neutrophils on the function of lung ventilation and to explore the influence of glucocorticoid on them and its mechanisms in patients undergoing open heart surgery.Methods: Thirty-six patients undergoing cardiac valve replacement operations were randomly allocated to three groups (with cases 12 each) control group (group C), hydrocortisone group (group HSS) and methylprednisolone group (group MPS). Saline was given intravenously two hours before the operation in group C or hydrocortisone sodium succinate (hydrocortisone, 5mg/kg) in group HSS or methylprednisolone sodium succinate (methylprednisolone, 10mg/kg) in group MPS, then hydrocortisone sodium succinate (hydrocortisone, 5mg/kg) was added to group HSS before cardiopulmonary bypass (CPB). Radial arterial blood gaseswere analyzed and spiro-index (RI), oxygenation-index (OI) and ratio of PaO2 to PAO2 (a/A) were calculated before anesthesia (T0), before CPB (T1) and 10 minutes (T2), 1 hour (T3), 2 hours (T4), 18 hours (T5), 28 hours (T6) after declamping of the superior veno cava and inferior veno cava. Dead space fraction (VD/VT) , peak inspiratory pressure (Ppeak), plateau inspiratory pressure (Pplat), static compliance (Cst) and airway resistance (RAW) were recorded at T1, T3 and T4. Pulmonary arterial blood samples were taken through Swan-Ganz catheter for the measurements of neutrophil cell count, neutrophil CD11b expression and neutrophil elastase at the time points above except for T0 and T6Results: (1) Compared with that at T1, although RI , OI and a/A were significantly changed at T4 ( P <0.01 or P <0.05 ) in three groups, RI of group C was higher significantly than that of group HSS and MPS ( P <0.01 ) and OI and a/A of group C were less than those of group HSS and MPS at T4 ( P<0.05 ) . (2) At T4, VD/VT, Ppeak and Pplat of group MPS were less than those of group C ( P <0.05 ) and Cst of group MPS was higher than that of group C ( P <0.05 ) . (3) Compared with that at T1, the levels of neutrophil cell count increased significantly from T 2 to T5 and reached to a peak values at T5 ( P <0.01 or P <0.05 ) in all groups. (4) Neutrophil CD11b expression was significantly higher at T2 and T3 than that at T, ( P <0.01 or P <0.05 ) in both group C and HSS, which at T5 returned to the level at T1. In group MPS, CDllb expression was not significantly changed from T1 to T4 but it was decreased significantly at T5 compared with that at T1 ( P <0.05 ) . The CD11b expression in group C was significantly greater than that in group HSS and MPS at T2 and T3( P <0.05 or P <0.01 ). (5) Compared with that at T1, the concentration of neutrophil elastase was elevatedsignificantly from T 2 to T4 ( P <0.01 or P <0.05) and returned at T5 in three groups, but the increase of it was significantly in group C than that in group HSS and MPS at all points of time ( P <0.01 or P <0.05 ) . (6) Partial correlation analysis showed that the neutrophil cell count in pulmonary arterial blood was well positively or negatively correlated to RI ( r = 0.1779, P <0.05 ), 01 ( r = -0.2413, P <0.01 ) and a/A ( r = -0.2013, P <0.05 ) and the concentration of neutrophil elastase was well positively or negatively correlated to RI( r = 0.3432, P <0.01 ), OI( r = -0.2943, P <0.01 ), a/A( r = -0.2996, P <0.01 ) , respectively.Conclusion: (1) After CPB, neutrophils were activated manifested by an increased of CDllb expression as upregulation and elastase release, which was followed by respiratory dysfunction. (2) The damage of respiratory function was closely correlated with neutrophils activation. (3) Preoperation in the patients undergoing cardiac valve replacement operations with methylprednisolone (10 mg/kg) or hydrocortisone (5 mg/kg, then added 5 mg/kg before CPB) for 2 hours may attenuate neutrophils activation in the pulmonary arterial blood and improve the respiratory function. |
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