Are small observational studies sufficient evidence for a recommendation of head-up sleeping in all patients with debilitating orthostatic hypotension? MacLean and Allen revisited after 70 years.
Are small observational studies sufficient evidence for a recommendation of head-up sleeping in all patients with debilitating orthostatic hypotension? MacLean and Allen revisited after 70 years.
复制标题
小型观察性研究是否有足够的证据来建议所有患有衰弱性直立性低血压的患者进行平视睡眠？
DOI：
10.1007/s10286-009-0522-3
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Thijs,RD
中科院分区：
文献类型：
--
作者：
Wieling,Wouter;Raj,SR;Thijs,RD
心输出量的过度下降是在平床上睡一夜后站立耐受性受损的基础，全身血管阻力不会改变[16]。虽然夜间多尿是自主神经功能衰竭患者的典型特征，但夜间睡眠后立位耐力的损害程度不能仅用夜间多尿来解释。在体重日差较小的患者中也可以发现立位耐力的显著昼夜变化。经肩胛骨液体转移被认为在这些患者中起重要作用[16，32，39]。尽管如此，已发现用加压素类似物去氨加压素治疗可有效减少夜间多尿和早晨体位性血压下降[14]。更复杂的是，卧床并没有实质性地改变昼夜血压变化[13]。因此，多种因素可能在昼夜血压变化中起作用，包括直立性液体移位、经毛细血管液体移位和引起钠和水排泄变化的神经体液节律。据报告，体重增加0.5-1 kg [1，12，16，27，34]（综述见[37]）。观察到头高位睡眠与下肢轻微水肿的出现相一致，这表明头高位诱导的容量变化（下肢细胞外液容量增加）发挥了重要的机制作用。小腿水肿被认为会导致腿部静脉血减少，从而减少清晨站立时每搏输出量和心输出量的过度下降[11，12，34]。麦克莱恩和艾伦通过将床头的柱子放在普通的厨房椅子上（40-45厘米高）来完成抬头姿势[11，12]。Ten Harkel使用12的抬头角（约30 cm的床头高度）[27]。班尼斯特等人已经应用了坐姿睡眠。[1]的文件。基于上面讨论的假定生理机制，陡峭的头向上倾斜睡姿可能是最有效的。重力应力是倾斜角的正弦函数，而不是倾斜角本身的函数。因此，Fan等人使用的倾斜角5 °将引起9%的全90 °立位载荷，倾斜角12 - 21%。然而，大多数患者及其伴侣难以忍受陡峭的倾斜角度。我们指导患者将床头放在20-30 cm的垫块上。在床垫下大腿水平处放一个硬枕头有助于防止滑倒。一
An excessive fall in cardiac output underlie the impairment in tolerance to standing after a night’s sleep on a flat bed, systemic vascular resistance does not change [16]. Although nocturnal polyuria is a typical feature of patients with autonomic failure, the degree of impairment in orthostatic tolerance after a night’s sleep cannot be explained only by the nocturnal polyuria. Marked diurnal variation in orthostatic tolerance can also be found in patients with small diurnal differences in body weight. Transcapillary fluid shifts are thought to play an important role in these patients [16, 32, 39]. Despite this, treatment with the vasopressin analogue desmopressin has been found effective in reducing both nocturnal polyuria and the postural blood pressure fall in the morning [14]. Adding to complexity, confinement to bed did not substantially alter the diurnal blood pressure changes [13]. Thus various factors may play a role in the diurnal BP changes including orthostatic fluid shifts, transcapillary fluid shifts and neurohumoral rhythms causing changes in sodium and water excretion.The physiological mechanisms underlying the beneficial effects of head-up sleeping are a decrease in sodium and water excretion during the night resulting in a better maintained and plasma volume; an increase in body weight of 0.5–1 kg is reported [1, 12, 16, 27, 34](for review see [37]). The observation that head-up sleeping becomes effective coincidental with the appearance of slight edema of the lower legs [5, 6, 15] suggests that head-up induced volume shifts, with an increased content of the extracellular fluid volume in the lower extremities, play an important mechanistic role. The lower leg edema is thought to result in diminished pooling of venous blood in the legs and thereby in decreasing the excessive fall in stroke volume and cardiac output during a stand-up in the early morning [11, 12, 34]. MacLean and Allen accomplished the head-up position by placing the posts of the head of a bed on ordinary kitchen chairs (40–45 cm high)[11, 12]. Ten Harkel used a head-up angle of 12 (about 30 cm elevation of the head of the bed)[27]. Sleeping in a sitting position has been applied by Bannister et al.[1]. Based on the presumed physiological mechanism discussed above, a steep head-up tilt sleeping position is likely to be the most effective. Gravitational stress is a function of the sine of the angle of tilt and not of the angle itself. Thus a tilt-angle of 5 as used by Fan et al. will induce 9% and a tilt-angle of 12 21% of the full 90 orthostatic load. However, a steep tilt-angle is difficult to tolerate by the majority of patients and their partners. We instruct our patients to put the head-end of their bed on 20–30 cm blocks. A hard pillow under the mattress at the level of the thighs has been found useful to prevent sliding down. A