依托咪酯除了稳定的血流动力学优点外，还有其它一些优点，包括改善心肌氧供与氧需间的比率（14,15），不会引起组胺释放（16），不会引起恶性高热（17），不会引起肝功能或肾功能的异常，不会引起分离麻醉现象和致幻等不良反应。依托咪酯引起的一个重要的不良反应就是呈剂量依赖性抑制肾上腺皮质功能（18），尤其表现在持续输注的时候。然而，没有报道显示，单次注射依托咪酯会引起促肾上腺皮质或皮质醇水平的下降或改变（1,19）。在一项随机分组的研究中，对行先天性心脏病手术患儿的研究发现，单次注射依托咪酯会引起血浆皮质醇的下降，而且这种下降一直持续到术后24小时，但这并不引起血流动力学的不稳定（10）。依托咪酯其它的不良反应，包括注射痛（由酸性pH值导致的）（20），不自主的骨骼肌收缩（肌阵颤），这是由于锥体外抑制的解除导致（21,22），还有震颤和惊厥（21–23），类过敏反应（23），以及可能抑制血小板功能（24）。我们没有测定肾上腺激素水平，单次注射依托咪酯，没有患儿发生肌阵颤或注射痛。

        我们的研究局限于小样本，而且我们只对有着相对正常心脏的儿童进行了研究。然而，每例患者与其自身进行对照，我们相信，依托咪酯至少对于由吗啡和咪唑安定镇静患儿的血流动力学影响是轻微的。我们研究的行射频消融的室上性心动过速的患儿具有正常的心脏结构，依托咪酯没有引起患儿心率的改变及心律失常。那些房间隔缺损的患儿有着轻度的血容量超负荷和升高的QpQs比值，依托咪酯对有着更明显容量或压力超负荷，心衰和肺动脉高压的儿童和婴儿血流动力学的影响还需要进一步的试验研究。

        在注射依托咪酯前使用咪唑安定和吗啡镇静对结果的影响还未确定。.吗啡和咪唑安定都有潜在的血流动力学副作用，可能会改变我们观测的依托咪酯的血流动力学参数。我们相信，在使用依托咪酯前，吗啡和咪唑安定对血流动力学的影响已经降到最小。如果对激动的儿童进行观测，结果会有所误导，在保留自主呼吸的前提下，对患儿进行置管监测之前，有必要对患儿进行镇静。去监测依托咪酯的诱导作用，避免正压通气和过高的吸入氧浓度，让条件尽可能接近基础状态也是非常重要的。这样我们才能在没有呼吸功能和气体交换发生实质性改变的条件下获得依托咪酯对血流动力学影响的数据。

       我们想尽量避免假阳性错误（一型错误），我们对数量众多的血流动力学变量采用更严格的统计标准，只有在双尾检验P < 0.01时才认为结果有统计学差异。这个研究的主要目的是评估所有12例患儿的测定结果，而且研究能够反映出差异性的变化。然而，统计结果还是有二型错误或者说是假阴性存在的可能性。对所有12例患儿的分析表明，二型错误发生的可能性为12%（见表2）。但因为病例分组样本很少（见表3），假阴性结果的可能性更高。我们计算出的，对于SVT或ASD组血流动力学数值的检测率为50%-60%，尽管我们在分组分析中没有看出显著性的差异，每组患者还需要更多的样本例数去降低假阴性的结果。

        单次注射依托咪酯后没有发生明显的血流动力学改变，这支持了依托咪酯能安全用于儿童麻醉诱导的建议。但对于依托咪酯用于有严重心室功能不全以及肺动脉高压的新生儿和儿童患者的安全性还需要进一步的工作。

        华译网上海翻译公司曾经翻译过大量有关依托咪酯能改善心肌氧供与氧需间的比率的资料文件，Beijing Chinese Subtitling Translation Service Agency has translated many technical documents about Etomidate can improve the ratio between myocardial oxygen supply and oxygen demand.

Besides hemodynamic stability, other advantages for etomidate include improved myocardial oxygen supply to demand ratio (14,15), lack of histamine release (16), absence of malignant hyperthermia (17), lack of effect on hepatic or renal function, and lack of dissociative and hallucinogenic side effects. A major side effect related to etomidate is dose-dependent adrenocortical suppression (18), particularly in response to a continuous infusion. However, there are reports that fail to demonstrate a decrease in cortisol or alterations in the adrenocorticotropic levels in patients after a single bolus dose of etomidate (1,19). In a randomized study investigating the effect of a single induction dose of etomidate on adrenocorticotropic hormone and cortisol levels in pediatric patients undergoing congenital cardiac surgery, plasma cortisol levels decreased with etomidate and remained low up to 24 hours postoperatively, but etomidate was not associated with hemodynamic instability (10). Other disadvantages of etomidate administration include pain on injection (as a result of its acidic pH) (20), involuntary skeletal muscle contractions (myoclonus) owing to disinhibition of extrapyramidal activity (21,22), tremors and seizure (21–23) anaphylactoid reaction (23), and possible inhibition of platelet function (24). We did not measure adrenocortical hormone levels, and none of our patients demonstrated involuntary movements or responded to bolus injection.
Our study is limited by our small sample size and we only studied children with relatively normal hearts. Nevertheless, with each patient acting as their own control, we believe it is possible to conclude that etomidate has minimal hemodynamic effects in at least healthy children sedated with morphine and midazolam. The children in our study who underwent radiofrequency catheter ablation for SVT had structurally normal hearts, and etomidate did not induce a change in heart rate or dysrhythmia. Those with an ASD had only a modest volume load and increased Qp: Qs, and further studies are necessary to determine the hemodynamic changes after etomidate in children and infants with more significant volume or pressure overload, heart failure, and pulmonary hypertension.

The influence of sedation with midazolam or morphine before etomidate administration is uncertain with regard to our results. Both morphine and midazolam have potential hemodynamic side effects that could have altered the hemodynamic measurements we observed after etomidate. We believe the time period over which morphine and midazolam were titrated until vascular access was obtained minimized their effect on hemodynamic measurements at the time of etomidate administration. Measurements of hemodynamic variables from an agitated child are also misleading, and sedation was necessary to gain vascular access in these children before measuring variables under conditions of spontaneous respiration. Further, to measure etomidate’s effect at induction, it was important to avoid both positive pressure ventilation and use of a higher Fio2, thereby maintaining conditions as close as possible to baseline. We were able to achieve this without substantial changes in respiratory function or gas exchange that could influence the hemodynamic measurements after etomidate administration.

We wanted to guard against false positive errors (Type 1) because of the large number of hemodynamic variables tested and thus used a stringent criterion for statistical significance, specifically, a two-tailed value of P < 0.01. The primary aim of this study was to evaluate changes in the outcome variables among all 12 patients, and the study was appropriately powered to detect significant change. There is, however, the possibility of a type II, or false negative, statistical result. When considering all 12 patients together for analysis (Table 2), we calculated the risk for a type II error to be 12%. However, because of the small number of patients in each subgroup (Table 3), there is an increased chance for a false negative result. The calculated power to detect changes in hemodynamic variables in the SVT or ASD groups is only 50%–60% and although we could not detect significant differences in a subgroup analysis, larger numbers of patients in each group are necessary to decrease the possibility of false negative results.

The lack of clinically significant hemodynamic changes after etomidate administration supports the recommendation that etomidate is safe in children. Further work is necessary to determine the hemodynamic profile of etomidate in neonates and in pediatric patients with severe ventricular dysfunction and pulmonary hypertension.