Light R B, Ali J, Breen P, Wood L D
Department of Medicine, University of Manitoba, Winnipeg, Canada.
J Surg Res. 1988 Jan;44(1):26-35. doi: 10.1016/0022-4804(88)90119-9.
Although catecholamine inotropic drugs are often used to support the circulation of critically ill patients with hypoxemic respiratory failure, their effect on the pulmonary circulation and on gas exchange is incompletely understood. In order to improve our understanding of the effects of these drugs on the pulmonary circulation, we made measurements of total and regional intrapulmonary shunt (Qs/Qt), distribution of pulmonary blood flow, and pulmonary hemodynamics before and after infusions of dopamine (n = 6, 5 micrograms/kg/min), dobutamine (n = 6, 10 micrograms/kg/min), isoproterenol (n = 6, 0.1 micrograms/kg/min), or saline in dogs with unilobar oleic acid-induced pulmonary edema. In addition to permitting determination of the overall hemodynamic and gas exchange effects of these drugs, this preparation allowed measurement of changes in distribution of pulmonary blood flow between normal and edematous lung. In 6 dogs given dobutamine, mean cardiac output (CO) increased by 1 liter/min, while pulmonary arterial pressure (PPA) increased by 2 mm Hg with no change in pulmonary vascular resistance (PVR) or distribution of pulmonary blood flow. There was a 5% increase in mean Qs/Qt which, because of the lack of evidence of pulmonary vasoactivity, was attributed to time or to increased CO. Isoproterenol produced a similar increase in CO, but reduced PPA and PVR indicating pulmonary vasodilator activity. Pulmonary vasodilation was most prominent in edematous lung, resulting in an increase in relative blood flow to the edema lung lobe and a substantial increase in Qs/Qt, exceeding the increase in all other groups. Dopamine, similarly increasing CO, did not change overall PVR but reduced fractional blood flow to the edema lobe by 3.4% of CO. Neither Qs/Qt nor PaO2 changed significantly in this group. The differing effects of these agents on pulmonary hemodynamics, intrapulmonary blood flow distribution, and gas exchange have potentially significant implications affecting the choice of drug used for circulatory support in hypoxemic respiratory failure.
尽管儿茶酚胺类正性肌力药物常被用于支持低氧性呼吸衰竭重症患者的循环，但它们对肺循环和气体交换的影响尚未完全明确。为了更好地理解这些药物对肺循环的影响，我们在单叶油酸诱导肺水肿的犬模型中，测量了输注多巴胺（n = 6，5微克/千克/分钟）、多巴酚丁胺（n = 6，10微克/千克/分钟）、异丙肾上腺素（n = 6，0.1微克/千克/分钟）或生理盐水前后的全肺和局部肺内分流（Qs/Qt）、肺血流分布及肺血流动力学。除了能够确定这些药物对整体血流动力学和气体交换的影响外，该模型还能测量正常肺和水肿肺之间肺血流分布的变化。在6只给予多巴酚丁胺的犬中，平均心输出量（CO）增加了1升/分钟，而肺动脉压（PPA）升高了2毫米汞柱，肺血管阻力（PVR）和肺血流分布无变化。平均Qs/Qt增加了５%，由于缺乏肺血管活性的证据，这归因于时间或CO增加。异丙肾上腺素使CO有类似增加，但降低了PPA和PVR，表明有肺血管舒张活性。肺血管舒张在水肿肺最为显著，导致流向水肿肺叶的相对血流量增加，Qs/Qt大幅增加，超过所有其他组。多巴胺同样增加了CO，但未改变整体PVR，但流向水肿肺叶的血流量占CO的比例减少了3.4%。该组中Qs/Qt和动脉血氧分压（PaO2）均无显著变化。这些药物对肺血流动力学、肺内血流分布和气体交换的不同影响，对低氧性呼吸衰竭循环支持用药的选择可能具有重要意义。
