体外循环围术期低三碘甲腺原氨酸综合征与低心输出量的关系

The Relationship of Perioperative Low T 3 Syndrome and Low Cardiac Output in Patients With Cardiopulmonary Bypass

目的：探讨体外循环心脏手术患者围术期低三碘甲腺原氨酸（Ｔ３）综合征与低心输出量发生的关系。方法：用放射免疫法测定２７例体外循环心脏手术患者术前、术后第２、７、１４天血清Ｔ３、四碘甲腺原氨酸（Ｔ４，即甲状腺素）、逆三碘甲腺原氨酸（ｒＴ３）及促甲状腺素（ＴＳＨ）的浓度变化；比较并发症组（ｎ＝６）与正常恢复组（ｎ＝２１）上述指标的动态变化水平。结果：术后全部患者血清Ｔ４、促甲状腺素浓度正常，Ｔ３降低，Ｔ３／Ｔ４、Ｔ３／逆三碘甲腺原氨酸比值降低，第７天可恢复正常。围术期Ｔ３降低在低心输出量、并发症组较正常恢复组显著，且持续时间长，恢复程度慢。其中术前２例己有Ｔ３降低者，术后降低更显著，并均发生低心输出量综合征。Ｔ３变化水平与临床预后及转归密切相关。结论：体外循环心脏手术患者围术期可呈现低Ｔ３综合征。术前血清Ｔ３水平低下和（或）术后更为显著降低的Ｔ３水平，可认为是术后低心输出量发生的重要体液因素。Ｔ３变化水平可作为体外循环围术期重症监测指标。

Objective:To study the relationship of perioperative low T 3 syndrome and low cardiac output in patients with cardiopulmonary bypass. Methods:The changes of serum concentrations of triiodothyronine(T 3),thyroxine(T 4),reverse T 3(rT 3) and thyroid stimulating hormone(TSH) in 27 patients with cardiopulmonary bypass were determined by radioimmunoassay on the preoperative day and 2 ,7 ,14 day after operation.The perioperative changes of the above mentioned parameters of the group with complication and the normal recovery group were analysed. Results:All patients had normal levels of serum T 4 and TSH,low level of serum T 3 and T 3/T 4,T 3/rT 3 ratio,and high level of serum rT 3 after operation and returned to normal on the 7th postoperative day.Perioperatively,the group with complication( n =6) of either low cardiac output or infection had lower T 3 level than normal recovery group( n=21)p <0.05,especially 2 patients with preoperative low T 3 syndrome,appeared to have both lower T 3 level and low cardiac output syndrome after surgery.The change of T 3 level closely correlated with the prognosis. Conclusions:Low T 3 syndrome may occur in patients with cardiopulmonary bypass perioperatively.Preoperative low T 3 and/or postoperative lowered T 3 in serum probably contribute to the incidence of low cardiac output.T 3 level may serve as a perioperative monitoring index of critical patients with cardiopulmonary bypass.