Disparity of isoflurane effects on left and right ventricular afterload and hydraulic power generation in swine
Disparity of isoflurane effects on left and right ventricular afterload and hydraulic power generation in swine
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DOI：
10.1097/00000539-199809000-00002
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发表时间：
1998-09-01
影响因子：
5.7
通讯作者：
Dickstein, ML
中科院分区：
文献类型：
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作者：
Heerdt, PM;Gandhi, CD;Dickstein, ML
麻醉药对心肌和血管的影响之间的相互作用对这些药物如何影响心脏的性能具有潜在的影响。大多数研究都集中在挥发性麻醉剂对左心室 (LV) 和体循环的影响。然而，右心室（RV）和肺循环是否以类似的方式做出反应尚不清楚。因此，在本研究中，我们检查了异氟醚对 LV 和 RV 收缩性以及总后负荷的剂量相关影响，以及对每个腔室产生的液压动力的同时影响的相关变化。研究了两组猪：一组在异氟烷之前未接受任何额外治疗（LSO，n = 6），另一组在异氟烷给药前接受六甲铵、阿托品和普萘洛尔以产生自主神经阻滞（ISO+AB，n = 4）。对于每个实验，测量 RV 和 LV 区域节段长度和压力，以及近端主动脉和肺动脉 (PA) 的当前血液和施用 0、0.5、1.0 和 1.5 最小肺泡麻醉浓度 (MAC) 异氟烷期间的压力。通过计算区域预负荷可复张行程工作斜率（PRSW）来评估收缩性。通过计算主动脉输入阻抗幅度 (Z)，以非搏动性和搏动性方式表征后负荷。根据这些数据，参考循环的三元件 Windkessel 模型确定总动脉阻力 (R)、特性阻抗 (Z(C)) 和血管顺应性 (C)。此外，还计算了每个心室的稳态（W-ss）、振荡（W-OS）和总液压功率输出（W-T）。在 ISO 组中，异氟醚使 LV 中的峰值收缩压降低幅度几乎是 RV 的三倍，但区域 PRSW 的剂量相关降低在两个心室中几乎相同。在主动脉中，异氟烷在 1.0 MAC 时使 R 最大程度降低 25%，并使 C 增加一倍，而 Z(C) 没有显着变化。或者，PA R 在 1.0 和 1.5 MAC 时从基线增加，而 Z(C) 在 1.5 MAC 时从所有其他值增加。 PA C 不被异氟烷改变。在 ISO+AB 猪中，基线 PA Z 高于 ISO 动物中明显的水平，但异氟烷没有改变。相比之下，ISO+AB 猪的基线主动脉 R 较低，但 1.0 MAC 异氟烷仍会适度降低。在 ISO 动物中，双心室的 W-T 和 W-SS 均表现出与剂量相关的下降，但所有剂量下 LV W-T 和 W-SS 的降低均大于 RV 的降低。因此，LV 的每单位流量的功率需求减少，但 RV 的功率需求保持不变。异氟烷也降低了两个心室的 W-OS。然而，LV W-OS 与 W-T 比率增加，这表明系统因脉动损失了更多功率。相比之下，在所有异氟烷剂量下，RV W-T 和 W-OS 的降低几乎是平行的，并且 W-OS 与 W-T 的比率没有变化。在 ISO+AB 组中，异氟烷引起的 LV 和 RV 功率特性的改变与 ISO 组相似。这些数据表明，尽管对双心室收缩力有相似的影响，异氟醚对右心室和左心室后负荷产生不同的影响，部分是通过自主神经活动的改变，影响稳态和脉动成分之间的功率输出分布。 意义：在这项研究中，我们检查了异氟醚对猪心脏性能的影响，发现虽然该药物同样抑制左心室和右心室的收缩，但它对反对力量有不同的影响血液的喷射。这些发现表明，组成心脏的两个相互依赖的泵可能会受到麻醉药物的不同影响。
The interaction between myocardial and vascular effects of anesthetics has a potential impact on how these drugs influence performance of the heart. Most studies have focused on volatile anesthetic effects on the left ventricle (LV) and systemic circulation. Whether the right ventricle (RV) and pulmonary circulation respond in a similar fashion, however, is unclear. In the present study, we therefore examined the dose-related effects of isoflurane on LV and RV contractility and total afterload and related changes to simultaneous effects on the hydraulic power generated by each chamber. Two groups of swine were studied: one received no additional treatment before isoflurane (LSO, n = 6), and the other received hexamethonium, atropine, and propranolol to produce autonomic blockade before isoflurane administration (ISO+AB, n = 4). For each experiment, measurements were made of RV and LV regional segment lengths and pressures, along with proximal aortic and pulmonary arterial (PA) blood now and pressure during the administration of 0, 0.5, 1.0, and 1.5 minimum alveolar anesthetic concentration (MAC) isoflurane. Contractility was assessed by calculating the regional preload recruitable stroke work slope (PRSW). Afterload was characterized in both nonpulsatile and pulsatile terms by calculating aortic input impedance magnitude (Z). From these data, total arterial resistance (R), characteristic impedance (Z(C)), and vascular compliance (C) were determined with reference to a three-element Windkessel model of the circulation. Additionally, steady-state (W-ss), oscillatory (W-OS) and total (W-T) hydraulic power output of each ventricle was calculated. In the ISO group, isoflurane produced a nearly threefold greater decrease of peak systolic pressure in the LV than in the RV, yet the dose-related decrease of regional PRSW was virtually the same in both chambers. In the aorta, isoflurane produced a maximal 25% reduction in R at 1.0 MAC and doubled C without a significant change in Z(C). Alternatively, PA R was increased from baseline at 1.0 and 1.5 MAC, whereas Z(C) was increased from all other values at 1.5 MAC. PA C was not altered by isoflurane. in ISO+AB pigs, PA Z at baseline was higher than that evident in ISO animals but was not altered by isoflurane. In contrast, baseline aortic R was lower in ISO+AB pigs but was still modestly reduced by 1.0 MAC isoflurane. In ISO animals, W-T and W-SS from both ventricles demonstrated dose-related deceases, but the reductions in LV W-T and W-SS were greater than those for the RV at all doses. Accordingly, the power requirement per unit flow decreased for the LV but remained constant for the RV. W-OS for both ventricles was also reduced by isoflurane. However, the LV W-OS to W-T ratio increased, which indicates that more power was lost to the system by pulsation. In contrast, reductions in RV W-T and W-OS were nearly parallel at all isoflurane doses, and the W-OS to W-T ratio was unchanged. In the ISO+AB group, isoflurane-induced alterations in LV and RV power characteristics were similar to those in the ISO group. These data indicate that, despite similar effects on biventricular contractility, isoflurane exerts qualitatively different effects on RV and LV afterload, in part via alteration in autonomic nervous activity, that influence the distribution of power output between steady-state and pulsatile components.Implications: In this study, we examined the effects of isoflurane on cardiac performance in swine and found that, although the drug depresses contraction of both the left and right ventricles similarly, it has different effects on forces that oppose the ejection of blood. These findings demonstrate that the two interdependent pumps that comprise the heart can be influenced differently by anesthetic drugs.