硅胶包埋永磁铁犬体内植入安全性的初步观察

Evaluation of biological safety of silicon membrane embedded permanent magnets implanted in canine

目的观察硅胶包埋永磁铁犬体内植入的生物安全性,探讨依据指南针原理设计的排尿报警装置临床应用的安全性。方法成年雄性犬,体质量11～12kg,随机分为实验组(n=8)和对照组(n=4):实验组植入硅胶包埋的直径10mm、厚3mm的钕铁硼永磁铁,其表面磁感应强度为0.30T;对照组植入同等规格的经硅胶包埋的钕铁硼合金。将植入物固定在膀胱前壁,饲养1年,观察其生存情况及局部病理变化,对比观察术前和术后犬尿液。结果实验组8只犬中,1只术后10h死于手术并发症,另1只术后3周因肠道内铁丝被永磁铁吸住而出现肠梗阻,其他6只犬和对照组4只犬术后一般情况良好,精神、食欲及二便无明显异常,切口愈合良好,无感染发生。术后1年处死,在这10只犬中,大网膜与膀胱壁在植入物周围发生粘连,植入物周围的纤维囊壁薄,其下方的膀胱壁增厚,膀胱黏膜面正常。植入物周围组织炎症反应和纤维囊级别均为2级。术前和术后尿常规无明显异常。结论钕铁硼永磁铁经硅胶包埋后具有良好的生物安全性,值得进一步研究。

Objective To investigate the biological safety of silicon membrane embedded permanent magnets implanted into canine,so as to evaluate the safety of a micturition alert device designed on the principle of compass.Methods Twelve adult male dogs（weighing 11-12 kg） were divided into experimental group（8 dogs） and control group（4 dogs）.The experimental group was implanted with a silicon membrane embedded NdFeB magnet,which was 10 mm in diameter and 3 mm in thickness and with a magnetic induction intensity of 0.3 Tesla at the center of the pole face surface.The control group was implanted with a silicon membrane embedded NdFeB alloy with the same dimensions.The grafts were sutured onto the anterior surface of the bladder wall.The dogs were then allowed to live for one year.Both the survival and local pathology around the grafts were observed after implantation.And the pre-operation urine and post-operation urine were compared between the two groups.Results One dog in the experimental group died from operation complications 10 hours after operation,another dog had intestinal obstruction 3 weeks after operation because iron wires in the intestinal tract was caught up by the permanent magnet.The rest 6 dogs in the experimental group and 4 dogs in the control group had no abnormalities in spirit,appetite,urine or stool,and there were no infections.The animals were sacrificed one year after operation.Adhension was found between the epiploon and the bladder wall around permanent magnets in these 10 dogs;the fibrous capsule around the permanent magnets was thin,and the local bladder wall below permanent magnets was thickened,with normal bladder mucosa.Grade 2 inflammatory reaction and fibrous capsule of the local tissue were noted around the grafts.The findings of urine routine were normal before and after operation.Conclusion NdFeB permanent magnets embedded with silicon membrane are biologically safe for clinical application,which warrants further investigation.