犬急性骨水泥肺栓塞的实验研究

Acute pulmonary embolism caused by PMMA:an experimental study in canines

目的通过股静脉注入骨水泥建立犬急性肺栓塞模型,探讨一定剂量范围内不同量骨水泥肺栓塞引起的生理病理变化间的差异。方法 18只成年家犬随机分成A、B、C 3组,每组6只,麻醉后行胸部CT平扫,穿刺右股静脉、左股动脉并置入血管鞘,经静脉鞘注入聚甲基丙烯酸甲酯(PMMA)A组0.5 ml,B组1 ml,C组2 ml。于注入PMMA前和注入后即刻、30 min及1 h分别检测血气分析、平均肺动脉压;于注入PMMA前、后5 min行肺动脉造影。术后1h行胸部CT平扫+增强。术后2 h将犬处死,开胸解剖观察大体形态后,沿肺动脉分支方向随机取肺组织3块进行病理学检查。结果 18只实验犬经股静脉注入PMMA操作均成功,经CT及病理证实均成功建立急性骨水泥肺栓塞模型。各组实验犬动脉血氧分压、二氧化碳分压在骨水泥注入前后差异均无统计学意义(P>0.05)。仅C组骨水泥注入后即刻平均肺动脉压为(24.12±1.74)mmHg,注入后30 min为(23.84±1.25)mmHg,注入后1 h为(24.17±1.63)mmHg,均较注射前的(16.47±0.55)mmHg差异有统计学意义(P<0.05)。A组、B组平均肺动脉压在骨水泥注入前后差异均无统计学意义(P>0.05)。各组实验犬术后胸部CT平扫均可见两肺高密度影,下肺多见,C组尤为明显。部分实验犬平扫见条索状阴影及肺不张征象。C组部分实验犬胸部增强CT可见肺动脉小分支内部分充盈缺损。肺动脉造影仅C组部分实验犬出现肺内部分细小血管减少,血管纹理稀疏,未见肺动脉主干及分支的充盈缺损。病理学检查均发现肺动脉分支存在骨水泥栓子,未见继发血栓形成。结论≤2 ml的骨水泥致急性肺栓塞的严重程度与注入骨水泥剂量没有相关性。在心肺功能正常情况下,≤2 ml的急性骨水泥肺栓塞不会引起明显的呼吸功能障碍。

Objective To establish acute pulmonary embolism model in canines by injecting bone cement（PMMA）,via the femoral vein,and to investigate the differences in physiopathological changes of acute pulmonary embolism caused by different volume of PMMA.Methods A total of 18 adult canis familiaris were randomly divided into three groups（A,B and C） with 6 dogs in each group.After the dogs were anaesthetized,thoracic plain CT scanning was performed,which was followed by puncturing of right femoral vein and left femoral artery,placement of vascular sheaths and injection of PMMA via venous sheath.The dose of PMMA used in group A,B and C was 0.5ml,1ml and 2ml,respectively.Blood gas and mean pulmonary arterial pressure were monitored continuously until 60 minutes after the injection,the results were recorded.The pulmonary angiography was carried out just before and 5 minutes after PMMA injection.One hour after the procedure,thoracic CT scanning,both plain and contrast-enhanced,was performed.The dogs were sacrificed two hours after the operation.The specimens of both lungs were collected and sent for histological examination.Results Technical success of injecting PMMA through femoral vein was achieved in all eighteen dogs,and the acute pulmonary embolism model was successfully established,which was proved by CT scans and pathological examination.After the injection of PMMA,both the blood partial pressure of oxygen（PO2） and the blood partial pressure of carbon dioxide（PCO2） in all three groups showed no statistically significant changes when compared with those determined before the injection.In group C,the mean pulmonary arterial pressure determined immediately,30 and 60 minutes after PMMA injection was（24.12 ± 1.74） mmHg,（23.84 ± 1.25） mmHg and（24.17 ± 1.63） mmHg respectively.The pre-injection mean pulmonary arterial pressure was（16.47 ± 0.55） mmHg.The difference in mean pulmonary arterial pressure was statistically significant between pre-injection value and post-injection ones.In group A and B,the post-injection mean pulmonary arterial pressure was not significantly different from the pre-injection value.In all experimental dogs,the post-operative plain CT scans showed that there were high-density shadows on both lungs,especially on lower lung field.In some dogs of group C,the CT scans demonstrated filling-defects in pulmonary arterial branches and signs of atelectasis.Angiography showed no evidence of the obstruction of pulmonary arterial trunk.Pathological examination found the cement emboli within the pulmonary branches,and no secondary thrombosis formation was seen.Conclusion No significant correlation exists between the severity of acute pulmonary PMMA embolism and the PMMA volume used in procedure if the dose is ≤ 2 ml.When the patient＇s cardiopulmonary function is under normal condition,acute pulmonary PMMA embolism caused by 2ml injection may not lead to an obvious respiratory insufficiency.（J Intervent Radiol,2012,21： 55-60）