讨论
在我们的研究中，患儿在单次注射依托咪酯（剂量为：0.3mg/kg）后，血流动力学的测量结果没有发现明显的有临床意义的改变。尽管试验例数少，当患儿依照诊断分类时，无论患儿有着结构正常的心脏（SVT组），还是有着轻度的容量超负荷（ASD组），在使用依托咪酯之前和之后都没有显示明显的改变。
在我们试验中发现的依托咪酯对小儿的血流动力学影响轻微与成人研究数据相一致（4，6）。以前曾有报道认为依托咪酯用于小儿诱导能改变患儿的心率，以及直接非有创监测下的血压数据（1，10）。在急诊室小儿快速顺序气管插管中，在非有创的血压监测下，有报道认为依托咪酯引起有临床意义的低血压的发生率很低（1,2）。在更大样本，近200例小于16岁的婴儿和儿童的研究中发现，以依托咪酯进行麻醉诱导，引起的血流动力学改变非常轻微（9）。在行小儿心脏置管术的研究中比较了依托咪酯，氯胺酮和珈玛羟丁酸钠的麻醉诱导作用，单次注射0.3mg/kg的依托咪酯不会引起患儿明显的心率和动脉压的改变（11）。
本次研究第一次通过有创的血流动力学和血氧饱和度的监测，对单次注射依托咪酯对小儿体循环血量和肺循环血量，以及全身血管阻力和肺血管阻力进行了充分的测量和评估。对于有着正常肺血管阻力基础值的SVT和ASD患儿，使用依托咪酯不会引起明显的有临床意义的改变。在SVT组，注射依托咪酯后二氧化碳分压有着微小但是不明显的升高，这可能反映了低通气状态的存在。如果存在肺血管反应的话，这种升高可能会导致肺血管阻力和肺动脉压的升高。然而，即使存在轻度的二氧化碳分压的升高，依托咪酯和肺血管阻力的升高之间也没有联系。对于基础性或原来就存在的肺动脉高压以及肺血管阻力升高的患儿，依托咪酯在这些患儿中使用的安全性需要进一步的评估。尽管在ASD组，肺血管阻力和全身血管阻力升高的趋势是不显著的，在有着更大肺循环血流量和体循环血流量比值的患儿，或在有着心室功能不全的患儿，血管阻力是否会进一步的升高还未可知。
华译网上海翻译公司曾经翻译过大量有关依托咪酯对小儿的血流动力学影响资料文件，Beijing Chinese Subtitling Translation Service Agency has translated many technical documents about The hemodynamic effects of etomidate in infant.
Discuss
In our study of children undergoing cardiac catheterization using direct hemodynamic measurements there were no clinically significant differences after a bolus injection of etomidate (0.3 mg/kg). Although the numbers are small, when patients were analyzed according to diagnosis, there were no differences before and after etomidate in those patients with a structurally normal heart (SVT) or those with a small volume overload (ASD).
The stable hemodynamic profile of etomidate we found in our small number of children is consistent with adult data (4,6). Previous reports of the hemodynamic effects of etomidate in pediatric patients have reported changes in heart rate and direct or noninvasive arterial blood pressure (1,10). Etomidate has been reported to have a low incidence of clinically significant hypotension based on noninvasive blood pressure measurement when used for rapid sequence tracheal intubation in pediatric patients in the emergency department (1,2). In a large study of nearly 200 infants and children up to 16 years of age, etomidate produced minimal hemodynamic changes during induction of anesthesia (9). In a study comparing etomidate, with ketamine and sodium gamma-hydroxybutyrate in children undergoing cardiac catheterization, etomidate 0.3 mg/kg bolus followed by a continuous infusion during cardiac catheterization did not cause significant changes in heart rate or arterial blood pressure (11).
Our study is the first in children to invasively measure hemodynamic and oxygen saturation data to allow a complete assessment of the changes in systemic and pulmonary blood flow and resistance related to bolus etomidate administration. There was no clinically significant change in PVR after etomidate in the SVT and ASD patients who all had a normal PVR at baseline. There was a slight but insignificant increase in Pco2 after injection of etomidate in the SVT group, which probably reflects hypoventilation. This increase could potentially increase PVR and PAP if there was a reactive pulmonary vasculature. However, etomidate was not associated with an increase in PVR despite the slight increase in Pco2. Additional evaluation in patients with baseline or existing pulmonary hypertension and increased PVR is necessary to determine the safety of etomidate in this patient population. Although there was an insignificant trend toward increased PVR and SVR in the ASD group, it is unknown whether vascular resistance may increase further in patients with a larger Qp:Qs ratio or in patients with ventricular dysfunction.
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