Comparison between conventional cystometry and stimulated filling cystometry by diuretics in a neurogenic bladder after spinal cord injury

OBJECTIVE: To determine in the neurogenic bladder whether cystometry performed under near physiologic condition by filling stimulation using diuretics reveals different findings compared with conventional cystometry (CMG). DESIGN: One group of subjects from a university teaching hospital was tested in two conditions. The maximum detrusor pressure (MPdet) and compliance of the bladder in CMG and furosemide-stimulated filling cystometry (FCMG) were compared in 27 patients with neurogenic bladder after spinal cord injury. The MPdet was estimated. Compliance was calculated. For CMG, the bladder was filled. FCMG was performed 3 hr after CMG. For FCMG, furosemide was injected after infusion of normal saline. Recording intravesical pressure started after emptying the bladder immediately after furosemide injection. RESULTS: Significant differences were found between CMG and FCMG in hyperreflexic neurogenic bladders with respect to a decrease in MPdet and increase in compliance with FCMG. However, there were no significant differences in MPdet and compliance in hyporeflexic or areflexic neurogenic bladders between the two techniques. CONCLUSION: We have found that FCMG is useful in evaluating both genuine MPdet and compliance in patients with hyperreflexic neurogenic bladder dysfunction. FCMG provides more reliable information on detrusor characteristics than CMG in hyperreflexic neurogenic bladder. We suggest that FCMG is an alternative, effective, and near physiologic diagnostic method, having short assessment time for improving evaluation of the detrusor characteristics of hyperreflexic neurogenic bladder.     

Cardiovascular control and plasma catecholamines during rest and mental stress: effects of posture.

In order to understand the complex autonomic adjustments that occur during the psychological challenges of normal daily life, autonomic responses to psychological stress were studied by evaluating the effects of body posture on various indices of sympathetic and parasympathetic regulation during performance of a psychological task. Twelve male subjects were studied in various postures (supine, sitting and standing), and during performance of the Colour Word Test (CWT) when sitting and then when standing. This procedure was subsequently repeated in reverse order (first standing and then sitting) after 15 min of supine rest. Blood samples for assay of plasma catecholamines were obtained before and during each CWT. Spectral analysis of beat-to-beat variations of heart rate (HR) and blood pressure (BP) was applied in order to obtain non-invasive indices of sympathetic and parasympathetic regulation. HR, diastolic BP, mid-frequency band power (0.07-0.14 Hz) of HR and systolic BP, and plasma adrenaline and noradrenaline concentrations showed significant increases when changing from supine to sitting to standing posture, whereas high-frequency band power (0.15-0.50 Hz) of HR decreased in a posture-dependent fashion. In the sitting position, the CWT caused significant increases in HR, BP and plasma adrenaline levels, and decreased HR and BP variability indices. In the standing posture, the CWT responses differed significantly from those during sitting for HR (a mild decrease during standing), high-frequency band power of HR (decreased more while sitting), high-frequency band power of BP (decreased more while standing), and plasma adrenaline responses (larger during sitting). Posture-related differential effects were observed on indices of sympatho-adrenomedullary activation during performance of a psychological challenge, whereas indices of parasympathetic activity indicated primarily less vagolytic effects when the task was performed in the standing posture. Our findings therefore underline the complexity of the adjustments that occur in neurohumoral and haemodynamic parameters during the psychological challenges of daily life.     

高血压患者不同体位动态血压的监测

目的了解高血压患者仰卧位、侧卧位、坐位、站立位动态血压测量有否不同。方法对51例动态血压监测的高血压患者,选用右上肢肱动脉测压法,分别测量不同体位的血压。结果仰卧位、左侧卧位、右侧卧位、坐位、站立位时的收缩压平均分别是152.10±14.55、129.21±14.92、150.42±15.54、149.87±14.84、147.85±12.67 mm Hg;舒张压平均分别是87.81±6.92、70.83±8.32、88.33±11.52、88.81±9.15、87.25±11.15 mm Hg。与仰卧位时动态血压测量的结果比较,左侧卧位时收缩压平均低22.89 mm Hg,舒张压平均低16.98 mm Hg,P<0.01;右侧卧位时收缩压平均低1.68 mm Hg,舒张压平均高0.52 mm Hg,P>0.05;坐位时收缩压平均低2.23 mm Hg,舒张压平均高1.00 mm Hg,P>0.05;站立位时收缩压平均低4.25 mm Hg,舒张压平均低0.56 mm Hg,P>0.05。结论高血压患者右侧卧位、坐位、站立位时与仰卧位时动态血压测量的结果无明显变化,左侧卧位时动态血压测量的结果显著低于仰卧位时动态血压测量的结果。     

The influence of autonomic diabetic neuropathy and human atrial natriuretic peptide on adrenal gland function in postural changes]

To investigate the influence of postural changes on plasma renin activity (PRA), plasma levels of human atrial natriuretic peptide (hANP) and on aldosterone in diabetes mellitus and autonomic neuropathy, ten patients with diabetes mellitus and autonomic neuropathy and ten patients with diabetes mellitus but without autonomic neuropathy were studied. Ten healthy subjects served as controls. Patients and controls were in supine position for 60 minutes, then changed posture sequentially to sitting (90 minutes) and to upright position (15 minutes). In controls, PRA was increased upon sitting and in the upright position, while hANP was decreased. Patients with autonomic neuropathy differed from controls in impaired renin stimulation, whereas in patients without autonomic neuropathy PRA responses to postural changes were only slightly decreased. In both groups of patients, the normal hANP responsiveness to postural changes was lacking. There were no differences in aldosterone levels between patients and controls. In patients with high basal hANP levels due to elevated systolic blood pressure renin responses to postural changes were decreased in comparison to those patients with low basal hANP levels. Thus, in patients with diabetes mellitus increased hANP levels which are not decreased in response to upright standing may contribute to the development of hyporeninism and its sequelae.     

Normal variation of plasma lipoproteins: postural effects on plasma concentrations of lipids, lipoproteins, and apolipoproteins.

We examined the effects of postural change on the concentrations of plasma cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, apolipoproteins (apo) A-I and B, and lipoprotein(a) [Lp(a)] in six volunteers who fasted 12 h before blood sampling. Baseline samples were drawn in the standing position; the subjects then assumed the supine or sitting position, and additional blood samples were drawn at intervals up to 40 min. They then returned to the standing position and were again sampled at intervals up to 40 min. In the supine position, lipid, lipoprotein, and apolipoprotein concentrations decreased rapidly within the first 5 min and stabilized after 20 min. Total and HDL cholesterol, apoA-I, apoB, and Lp(a) decreased by as much as 7-12% in the supine position and returned to baseline values 20-40 min after the standing position was resumed. Smaller changes (5-9%) were observed when the subjects were sitting, and returned to baseline within 20 min after the subjects resumed the standing position. The decrease in triglycerides was 17% in the supine position and 10-11% in the sitting position. Lp(a) concentrations decreased 7-8% in either the supine or sitting position and returned to baseline more slowly than did the other components. For all components the changes were most rapid within the first 10 min after changing posture.     

Effect of body position on foot and ankle volume in healthy subjects

Physical therapy treatments for and evaluation of lower limb swelling are usually performed in supine lying position. However, the limb is usually treated or assessed in the dependent position, i.e. sitting or standing. The purpose of this study was to determine the possible confounding effect of subject positioning on foot and ankle volume. Sixty healthy individuals were randomly positioned into motionless standing, sitting or supine lying for 30 min. Volumetric measurements of the dominant leg were taken with a foot and ankle volumeter before and after 30 min of positioning. A significant difference between the three groups for foot and ankle volume change (F(2,53) = 35.41, P<0.001) was found. A post-hoc Tukey HSD test revealed that the difference was statistically significant between sitting and standing as well as supine lying and standing (P<0.001). No statistical significance was found between sitting and supine lying (P = 0.90). Standing caused the greatest increase in foot and ankle volume followed by sitting then supine lying. The results indicate that treating or assessing a limb with the subject in a sitting position would not be significantly different from a subject who is positioned in supine lying. However, it is not known whether the height and the distance from the heart to the feet were comparable between the groups, and so it is recommended that, where possible, treatment and assessment of lower leg swelling should be undertaken with the leg in a non-dependent position and definitely not in standing.     

Extracranial vascular reactivity in migraine and tension headache

The amplitude of temporal artery pulsation was monitored at rest, after standing from the sitting position and after exercise in 23 normal controls, 10 patients subject to chronic tension headache and 107 migrainous patients. The pulses of migrainous patients did not differ from normal at rest or on standing. On exercise, the temporal artery on the habitually affected side of migrainous patients dilated more than the headache-free side, while exercise-induced changes in tension headache patients were less than those in normal controls. The responses were not influenced by previous or current medication.     

Variations of ambulatory blood pressure with position in patients with type 1 diabetes: influence of disease duration and microangiopathy in a pilot study

OBJECTIVE: To study the influence of position changes on 24-h ambulatory blood pressure (ABP) in normotensive or mildly hypertensive normoalbuminuric patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: A cross-sectional evaluation of patients was staged according to the duration of diabetes (DD) and the presence of microangiopathy. We recruited 37 patients (30 men and 7 women), aged 38 +/- 12 years, who were normotensive or mildly hypertensive (diastolic blood pressure [DBP] <105 mmHg) and free of antihypertensive treatment and microalbuminuria. They were included according to DD (group 1, <5 years; group 2, > or =10 years). An additional group of seven diabetic patients with microalbuminuria and mild untreated hypertension was also investigated. We recorded 24-h ambulatory blood pressure every 15 min with a position sensor, which allowed for the discrimination between standing or supine/sitting position in the patient. RESULTS: Mean daytime (10:00 A.M. to 8:00 P.M.) ABP in supine/sitting position did not significantly differ between groups 1 and 2. However, standing ambulatory systolic blood pressure (ASBP) and ambulatory DBP (ADBP) were significantly higher than supine/sitting ASBP and ADBP in group 1 (DeltaSBP 4 +/- 5, DeltaDPB 4 +/- 6 mmHg, P < 0.01) but not in group 2 (DeltaSBP 2 +/- 8, DeltaDBP 2 +/- 4 mmHg, P = NS). Patients free of microangiopathy presented with significantly higher ABP in standing position than in sitting/lying position, whereas patients with retinopathy and/or nephropathy exhibited no significant increase of ABP during standing. CONCLUSION: The monitoring of position during ambulatory measurement of blood pressure in type 1 diabetic patients shows different patterns in relation to disease duration and the presence of microangiopathy.     

Physiological responses to the early mobilisation of the intubated, ventilated abdominal surgery patient

The aim of this study was to investigate the effects of mobilisation on respiratory and haemodynamic variables in the intubated, ventilated abdominal surgical patient. Mobilisation was defined as the progression of activity from supine, to sitting over the edge of the bed, standing, walking on the spot for one minute, sitting out of bed initially, and sitting out of bed for 20 minutes. Seventeen patients with age (mean +/- SD) 71.4 +/- 7.1 years satisfied inclusion criteria. Respiratory and haemodynamic parameters were measured in each of the above positions and compared with supine. In the 15 subjects who completed the protocol, standing resulted in significant increases in minute ventilation (VE) from 15.1 +/- 3.1 l/min in supine to 21.3 +/- 3.6 l/min in standing (p < 0.001). The increase in VE in standing was achieved by significant increases in tidal volume (VT) from 712.7 +/- 172.8 ml to 883.4 +/- 196.3 ml (p = 0.008) and in respiratory rate (fR) from 21.4 +/- 5.0 breaths/min to 24.9 +/- 4.5 breaths/min (p = 0.03). No further increases were observed in these parameters beyond standing when activity was progressed to walking on the spot for one minute. When supine values were compared with walking on the spot for one minute, inspiratory flow rates (VT/TI) increased significantly from 683 +/- 131.8 ml/sec to 985.1 +/- 162.3 ml/sec (p = 0.001) with significant increases in rib cage displacement (p = 0.001) and no significant increase in abdominal displacement (p = 0.23). Arterial blood gases displayed no improvements following mobilisation. Changes in VT, fR, and VE were largely due to positional changes when moving from supine to standing.     

Postural effects on diastolic blood pressure are differently recorded by a non-invasive ambulatory blood pressure monitor and a standard auscultatory device,

Summary. The aim of this study was to determine the influence of change of posture on blood pressure as recorded with an automatic ambulatory blood pressure monitor and a standard auscultatory device. The blood pressure difference between sitting and supine and between standing and supine posture was 1.1/3.9 and 6.5/6.3 mmHg, respectively, for the monitor recordings, and 0.7/6.7 and 7.9/14.8 mmHg, respectively, for the standard recordings. All differences were significant, except the systolic blood pressure difference between sitting and supine posture. There were no significant differences in systolic blood pressure between monitor and standard recordings in any posture. The corresponding differences in diastolic blood pressure were significant in sitting (-4.6 mmHg) and standing postures (-10.3 mmHg), but not in supine posture (-1.8 mmHg). It is concluded that a change of posture contributes to blood pressure variability, and agreement between diastolic blood pressure in supine subjects, as recorded by an ambulatory monitor and a standard device, does not necessarily mean agreement in standing (or sitting) subjects.     

老年高血压患者不同体位血压的研究

目的测定老年高血压患者立位、坐位和卧位不同体位血压的变化及餐后血压的变化。方法本实验随机抽取2009年1月-2010年6月新疆医科大学第五附属医院门诊或住院60岁以上110例老年高血压患者1、05例老年非高血压患者1、02例中年高血压患者,采用台式水银血压计柯氏音听诊法,测定卧位、坐位、立位血压,同时监测靶器官损害的发生率进行分析。结果老年高血压组立位收缩压及舒张压显著下降,与坐位、卧位比较有显著性差异（P〈0.01）,而卧位收缩压及舒张压显著上升,与立位及坐位比较有统计学意义（P〉0.01）;老年非高血压组立位收缩压及舒张压显著下降,与坐位、卧位比较有显著性差异（P〈0.05）,而坐位与卧位收缩压及舒张压比较差异无统计学意义（P〉0.05）;中年高血压组卧位、坐位、立位收缩压及舒张压的比较差异无统计学意义（P〉0.05）。老年高血压病患者靶器官损害率也高于中青年高血压患者。结论不同位体测量血压对老年高血压患者测量值影响较大。     

Plasma catecholamine responses to change of posture in alcoholics during withdrawal and after continued abstinence from alcohol

Plasma catecholamine, blood pressure and heart rate responses to standing were measured in ten alcoholics during withdrawal, ten alcoholics after 2-7 weeks of abstinence from alcohol, six abstinent alcoholics with orthostatic hypotension and ten normal control subjects. Withdrawing alcoholics had supine and standing heart rates and plasma noradrenaline and adrenaline concentrations that were higher than in abstinent alcoholics or control subjects. Supine blood pressures were also higher in withdrawing alcoholics than in abstinent alcoholics or control subjects, but on standing blood pressures in withdrawing alcoholics fell, four patients having a fall of more than 30/5 mmHg. Abstinent alcoholics without orthostatic hypotension had higher basal and standing concentrations of noradrenaline than control subjects but normal heart rates and adrenaline concentrations. Abstinent alcoholics with orthostatic hypotension showed a wide range of basal plasma noradrenaline concentrations and were found to have variable plasma noradrenaline responses to standing, three subjects having normal responses and three subjects having no or little increase in plasma noradrenaline on standing. It is concluded that alcohol withdrawal is associated with increased sympathetic nervous activity, as reflected by raised supine and standing plasma concentrations of catecholamines, and that even after 2-7 weeks of abstinence from alcohol plasma noradrenaline concentrations may be higher than in control subjects. Despite increased sympathetic nervous responses to standing, alcoholics during withdrawal have impaired blood pressure control and some may exhibit orthostatic hypotension. Orthostatic hypotension may also be observed in alcoholics during continuing abstinence from alcohol; in some of these patients failure of reflex noradrenaline release in response to standing may contribute to orthostatic hypotension.     

Detrusor and blood pressure responses to dorsal penile nerve stimulation during hyperreflexic contraction of the bladder in patients with cervical cord injury

OBJECTIVE: To investigate the immediate effect of dorsal penile nerve (DPN) stimulation on detrusor pressure (P(det)) and blood pressure during hyperreflexic contractions of the bladder in patients with cervical spinal cord injury (SCI). DESIGN: Blood pressure and P(det) monitoring during cystometry with and without DPN stimulation. SETTING: Urodynamic laboratory in a university hospital in Korea. PARTICIPANTS: Eight men (age range, 20-55y) with cervical SCI that was incurred from 4 months to 10 years before this study. INTERVENTION: During water cystometry, blood pressure was monitored with an intra-arterial catheter introduced percutaneously into the radial artery and was recorded simultaneously with the P(det). Blood pressure was also measured manually with an electronic blood pressure cuff. Electric stimulation was applied to the DPN by using surface electrodes each time a bladder contraction was detected. Stimulation intensity was twice the threshold of the pudendal-anal reflex. MAIN OUTCOME MEASURES: P(det), systolic blood pressure, and diastolic blood pressure. RESULTS: As P(det) increased, the blood pressure increased in all cases. All the reflex contractions of the bladder were effectively suppressed by DPN stimulation, and as the P(det) decreased during stimulation, radial arterial pressure also decreased immediately and significantly. CONCLUSIONS: DPN stimulation can decrease P(det) and the increased blood pressure associated with it.     

Oblique abdominal muscle activity in standing and in sitting on hard and soft seats

The activity of the oblique abdominal muscles was investigated with the trunk in unconstrained, symmetrical and static postures. Electromyographic recordings in six healthy subjects revealed that in all subjects the activity of both the internal and the external obliques is significantly higher in unconstrained standing than in supine posture. Activity of the internal oblique was higher than that of the external oblique abdominal. The sacrospinal, gluteus maximus and biceps femoris muscles showed practically no activity in unconstrained erect posture. During unconstrained sitting both oblique abdominals are active. In most subjects the activity of the oblique abdominals was significantly smaller when sitting on a soft car seat than when sitting on an office chair with a hard seat. The possibility is discussed that contraction of the oblique abdominals in unconstrained standing and sitting may help in stabilizing the basis of the spine and particularly the sacroiliac joints. During standing and sitting the oblique abdominal muscles apparently have a significant role in sustaining gravity loads. RELEVANCE: Back pain and pelvic pain are often experienced in prolonged standing and sitting postures. In these postures the oblique abdominals are shown to be active. The present study gains clinical significance by the studies showing relatively small oblique abdominal muscle strength in patients with low back pain. A soft seat may be helpful in treatment and prevention, because it substitutes oblique abdominal muscle activity.     

Changes in blood pressure in the sitting and standing positions in hypertensive patients

Ersoy S, Pinar R, Ersoy IH. International Journal of Nursing Practice 2011; 17 : 105–109 Changes in blood pressure in the sitting and standing positions in hypertensive patients Most guidelines for management of hypertension do not give special preference to a specific position of patient during blood pressure (BP) measurement, suggesting that BP readings taken with patients sitting, supine and standing are equivalent. The objective of this study was to examine whether there was any difference between BP readings with hypertensive participants comfortably sitting on chair and those with participants standing with the arm supported horizontally at the right atrial level. BP was measured twice each for 168 hypertensive patients (medicated and unmedicated) at sitting, standing and sitting positions, respectively, with a mercury‐filled column sphygmomanometer. We found significantly lower in systolic and diastolic BP readings in standing position than in sitting position. The present study indicates that the BP readings are related to the posture; thus, BP measured in different positions cannot automatically be regarded as equivalent.     

Effects of physical training on straightening-up processes in patients with Parkinson's disease

Purpose: The aim of this study was to evaluate whether motor training could improve the straightening-up sequences in patients with Parkinson's disease and, consequently, could ease the capacity of the patients to change body's position. Methods: Twenty out-patients with idiopathic Parkinson's disease (12 males, 8 females; mean age 72,9; H-Y, 1, 5-3) were enrolled in a rehabilitationprogramme which included exercises for the mobility of the trunk, of upper and lower limbs and of each segment of the spine, in order to improve the coordination of movement and to avoid postural disturbances. They received 1 hour of group treatment twice a week for a 5 week consecutive period. No changes were made in the pharmacological treatment received by each patient. The patients were evaluated at the beginning and at the end of the rehabilitation training. The statistical evaluation was made using the Wilcoxon test. Results: Statistically significant differences were observed in all the motor parameters that were evaluated (supine to sitting and sitting to supine, supine rolling, standing from a chair). Conclusions: The observations demonstrate that physical training can be effective in improving motor performance related to changes in position which affects the simple daily activities of the patients.     

Nocturnal oximetry: utility in the respiratory management of amyotrophic lateral sclerosis

OBJECTIVE: Current recommendations are to institute nocturnal nasal ventilation for amyotrophic lateral sclerosis patients with a forced vital capacity (FVC) of <50% of predicted normal. The purpose of this study was to determine whether this is appropriate. DESIGN: A total of 87 nocturnal oximetry evaluations were performed on 78 consecutive amyotrophic lateral sclerosis patients symptomatic for sleep-disordered breathing. Nocturnal oximetry measurements were compared for those with FVC >50% vs. those with FVC of <50% of normal. FVC was measured sitting and supine. RESULTS: A considerable number of these symptomatic patients manifested evidence of nocturnal hypoxemia as measured by oximetry. However, there was no significant difference between patients with sitting percentage-predicted FVC above and below 50% predicted in minimum oxygen saturation, mean oxygen saturation, percentage of time spent with oxygen saturation of <88%, and number of events per hour. There was no significant difference between patients with supine percentage-predicted FVC above and below 50% predicted in minimum oxygen saturation, mean oxygen saturation, percentage of time spent with oxygen saturation of <88%, and number of events per hour. CONCLUSION: The recommendation that FVC be <50% of normal is inappropriate for justifying introduction of nocturnal nasal ventilation. Many patients are symptomatic at higher FVC and manifest evidence of nocturnal hypoxemia. Nocturnal oximetry adds additional practical information for justifying earlier respiratory intervention for symptomatic patients.     

Urodynamic evaluation of voluntary detrusor response in healthy subjects

The ability of healthy subjects to voluntarily inhibit a bladder detrusor contraction was evaluated using standard urodynamic techniques. Ten healthy subjects (five men and five women) were appraised using trichannel techniques which included measuring bladder volume, bladder pressure, intraabdominal pressure, and electromyographic activity of the anal or external urethral sphincter. Each subject was first evaluated to determine normalcy of urine flow rate. All subjects were assessed in three positions: supine, sitting, and standing. All ten subjects were able to inhibit their detrusor responses without increasing external urethral or anal sphincter activity or raising the tonus pressure limb of the bladder. Three of the subjects were unable to void during any part of the urodynamic evaluation. In one subject, voiding was accomplished by Valsalva maneuver which mimicked detrusor contraction. At least two subjects did not demonstrate their first urge to void until 300 to 400 cc, and one of these individuals was unable to void until his bladder capacity reached 600cc. These results indicated that normal subjects can inhibit their detrusor response during urodynamic studies. Inability to inhibit this response would therefore appear to be an abnormal pattern. Conversely, inability to produce a detrusor response cannot be called an abnormal retention pattern. Bladder volumes in healthy subjects may be higher than the traditional norms, and this must be taken into account during urodynamic evaluations.     

Effects of physical training on straightening-up processes in patients with Parkinson's disease

Purpose: The aim of this study was to evaluate whether motor training could improve the straightening-up sequences in patients with Parkinson's disease and, consequently, could ease the capacity of the patients to change body's position. Methods: Twenty out-patients with idiopathic Parkinson's disease (12 males, 8 females; mean age 72,9; H-Y, 1, 5-3) were enrolled in a rehabilitationprogramme which included exercises for the mobility of the trunk, of upper and lower limbs and of each segment of the spine, in order to improve the coordination of movement and to avoid postural disturbances. They received 1 hour of group treatment twice a week for a 5 week consecutive period. No changes were made in the pharmacological treatment received by each patient. The patients were evaluated at the beginning and at the end of the rehabilitation training. The statistical evaluation was made using the Wilcoxon test. Results: Statistically significant differences were observed in all the motor parameters that were evaluated (supine to sitting and sitting to supine, supine rolling, standing from a chair). Conclusions: The observations demonstrate that physical training can be effective in improving motor performance related to changes in position which affects the simple daily activities of the patients.     

Plasma volumes,noradrenaline levels and renin activity during posture changes in end-stage renal failure

Summary. In nine normal subjects and nine patients with end-stage chronic renal failure (CRF) we studied the effect of prolonged (110 min) postural changes on the plasma volume, intrathoracic volume, plasma noradrenaline concentration, haemodynamic variables, and plasma renin activity (PRA). Upon standing, plasma volume decreased rapidly by about 11% in both groups as measured from the control volume and changes in haematocrit. This was accompanied by identical increments of plasma colloid osmotic pressure. The changes in intrathoracic volume (monitored by measurement of the electrical impedance of the thorax), as well as the alterations in plasma noradrenaline, blood pressure, and heart rate, were also comparable in the two groups. These similarities were in contrast with divergent responses of PRA. The increase in PRA on standing was significantly blunted in the CRF patients compared with the normal response (to 1.4±0- 4 fold of the supine value in CRF v. 6.0±3.2 fold in the normals, P < 0.0004). It is concluded that the attenuated increase in PRA upon standing in patients with CRF is not a consequence of diminished sympathetic stimulation or an altered response of the intravascular volume. Second, the unabated decrease in plasma volume upon standing pleads against a decrease of tissue compliance in CRF.