Esforzado Armengol N, Cases Amenós A, Bono Illa M, López-Pedret J, Revert Torrellas L
Servicio de Nefrología, Hospital Clínic i Provincial, Barcelona.
Med Clin (Barc). 1994 Mar 5;102(8):285-9.
Chronic hypotension is a not uncommon complication among hemodialyzed patients which is responsible of an important morbidity. The autonomic nervous system (ANS) dysfunction seems to play a key role in the pathogenesis of chronic hypotension.
In order to study whether ANS dysfunction is responsible for chronic hypotension in hemodialyzed patients, the authors evaluated the integrity of the whole baroreflex arc by the Valsalva's manoeuver, of parasympathetic efferent pathway by the deep-breathing test and of sympathetic efferent pathway by the hand-grip test in 16 hemodialyzed patients with chronic hypotension, 17 normotensive hemodialyzed patients and 17 normal control subjects. Plasma catecholamine levels were also measured in these patients.
In normotensive patients, Valsalva's manoeuver response (p < 0.005) and deep-breathing test response (p < 0.05) were lowered, while hand-grip test response was preserved. In chronic hypotensive patients, in addition to an impaired deep-breathing test (p < 0.05), a further reduced Valsalva's manoeuver response and a lower pressor response to hand-grip test were observed (p < 0.001). Catecholamine levels were higher in both groups of patients (p < 0.01) with respect to control subjects, specially in chronic hypotensive patients.
In hemodialyzed patients (both normotensive and hypotensive) the whole baroreflex function and parasympathetic response are impaired. The lower pressor response to hand-grip test observed in hypotensive patients, in spite of the higher catecholamine levels, suggest that in these patients the cardiovascular dysfunction cannot be ascribed to a reduced sympathetic "outflow" but to a resistance of the target organs (heart and vessels) to the sympathetic stimulation.
慢性低血压是血液透析患者中并不罕见的并发症，会导致严重的发病率。自主神经系统（ANS）功能障碍似乎在慢性低血压的发病机制中起关键作用。
为了研究ANS功能障碍是否导致血液透析患者的慢性低血压，作者通过瓦尔萨尔瓦动作评估了16例慢性低血压血液透析患者、17例血压正常的血液透析患者和17例正常对照者的整个压力反射弧的完整性，通过深呼吸试验评估了副交感神经传出通路的完整性，通过握力试验评估了交感神经传出通路的完整性。还测量了这些患者的血浆儿茶酚胺水平。
在血压正常的患者中，瓦尔萨尔瓦动作反应（p<0.005）和深呼吸试验反应（p<0.05）降低，而握力试验反应保持正常。在慢性低血压患者中，除了深呼吸试验受损（p<0.05）外，还观察到瓦尔萨尔瓦动作反应进一步降低，以及对握力试验的升压反应更低（p<0.001）。两组患者的儿茶酚胺水平均高于对照者（p<0.01），尤其是慢性低血压患者。
在血液透析患者（包括血压正常和低血压患者）中，整个压力反射功能和副交感神经反应均受损。尽管儿茶酚胺水平较高，但低血压患者对握力试验的升压反应较低，这表明在这些患者中，心血管功能障碍不能归因于交感神经“输出”减少，而是归因于靶器官（心脏和血管）对交感神经刺激的抵抗。
