Effect of inhaling specific phosphodiesterase inhibitor on lung injury induced by cardiopulmonary bypass

Objective To evaluate the effect of pretreatment by inhaling specific phosphodiesterase inhibitor on lung injury induced by cardiopulmonary bypass(CPB). Methods From April 2010 to November 2010,30 patients were divided randomly into two groups:control group(n=15)and milrinone group(n=15). In milrinone group,5 mg milrinone diluted by 5 ml normal saline was inhaled per 8 h two days pro-operation. In control group,only 10 ml normal saline was inhaled. Blood samples were drawn from ulnar vein and radial artery pre-operation(To),30 min post-aortic unclamping(T1),at the end of operation (T2),24 h,72 h and 7 d post-operation(T3-T5). The following parameters were determined: TNF-α(tumor necrosis factor-alpha),IL-6(interleukin-6),HSCRP(high-sensitivity C-reactive protein),MDA (malondialdehyde),MPO(myeloperoxidase)level and lencocyte count ratio of venous and arterial blood. And the values of pulmonary vascular resistance(PVR)and oxygenation index(OI)were measured through a Swan-Ganz catheter at the first 5 time points. Results PVR rose while OI declined at post-operation. But the range of above-mentioned indices in milrinone group was significantly smaller than that in control group. And the indices recovered much earlier in milrinone group. The levels of TNF-αIL-6,HSCRP,MDA,MPO and lencoeyte count ratio were not significantly different at To between two groups and increased significantly after CPB in both groups. But the level of TNF-α[(ng/L)was significantly lower at T2,T4,T5 in milrinone group than that in control group(60 ±5 vs 79 ±7,29±6 vs 40 ±8,18 ±5 vs 28±7, all P <0. 05). The levels of IL-6 and MDA were significantly lower at T1 - T4 in milrinone group. The level of HSCRP became elevated post-operatively in both groups and reached its peak at 24 h post-operation,especially in control group. The level of MPO (μg/L)was significantly lower at T2, T3 and T5 (134 ± 20 vs190 ±23,142±28 vs 178 +20,65±9 vs 75 ± 11, all P <0. 05). And the V/A ratio was significantly lower at T1 - T3 in milrinone group than in control group ( 1. 12 ~ 0. 11 vs 1. 37 ± 0. 09,1. 07 ± 0. 07 vs 1. 25 ±0. 07, both P < 0. 01 ). Conclusions Inhaled milrinone may protect the lungs from acute injury induced by CPB. Inhaling milrinone is safe and feasible for the prevention of acute CPB-induced injury. Key words: Phosphodiesterase inhibitors ;  Milrinone ;  Extracorporoal circulation ;  Respiratory