Prone position favors motor development of infants

OBJECTIVE: To determine the motor development in infants sleeping in the supine position compared to infants sleeping in the prone position, and to compare the levels of motor development of infants playing only in the supine position and of infants playing in the prone position as well. DESIGN: Prospective blinded comparing study. SETTING: Department of Physical Therapy, Maasziekenhuis, Boxmeer, the Netherlands. METHODS: Various measuring instruments were used in the home environment to determine the levels of motor development at the age of 5 months of 21 healthy infants born at term selected from a group of 160 infants attending the infant welfare clinic. RESULTS: Infants sleeping in the prone position (n = 8) showed a higher motor development than infants sleeping in the supine position (n = 13). Infants playing in the prone and supine position (n = 5) had a higher motor development than infants who played exclusively in the supine position (n = 15). CONCLUSION: Sleeping and playing in the prone position was accompanied by a higher motor development in healthy mature-born infants at the age of 5 months.     

Power spectral analysis of heart rate variability during graded head-up tilting in patients with vasodepressor syncope

1. Two groups of age- and sex-matched subjects, eight healthy controls and 10 patients, suffering from recurrent vasodepressor syncope, participated in a study to examine autonomic function and sequential changes in power distribution of heart rate (HR) variability during graded head-up tilt. 2. The following autonomic function tests were performed: valsalva ratio, HR responses to deep breathing and posture, BP responses to sustained handgrip and postural change. Each subject was tilted at 15 degrees, 30 degrees, 45 degrees, 60 degrees and 80 degrees head-up, each for 15 min, or until symptoms occurred. The eight control subjects completed the tilt study without any symptoms, while all 10 patients developed presyncope and/or syncope at various tilt angles. 3. Resting blood pressure (BP) was lower in the patient group, while resting HR, autonomic function tests and resting HR variability components were similar in the two groups. 4. The control group showed a progressive increase in low frequency power component (LF) from supine to end tilt (delta LF 20.06 +/- 14.50%) and a progressive fall in high frequency (HF) component (delta HF - 24.62 +/- 10.64%). In contrast, in the patient group, LF fell during tilt in the presyncope period (delta LF - 10.57 +/- 12.93%, P < 0.01 vs control group). HF and HF:LF ratio responses did not differ significantly in the two groups. 5. At end tilt, the increase in plasma noradrenaline was significantly greater in the control group than in the patient group (delta NA 0.83 +/- 0.27 vs 0.28 +/- 0.14 pmol/mL, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

The importance of vitamin B 6 for development of the infant. Human medical and animal experiment studies

Thirteen healthy subjects were tested for parasympathetic reactivity during head-up tilt and reversal of the tilt. Head-up tilt (70 degrees) resulted in significant increase in baseline heart rate and diastolic blood pressure. Head-up tilt also led to increased parasympathetic reactivity as measured by Valsalva manoeuvre and hand grip test. Heart rate response to deep breathing test did not change. The reversal of the tilt led to returning of heart responses to original values. Responses indicate towards enhanced parasympathetic reactivity during head-up tilt position.     

Effects of passive tilt and submaximal exercise on spectral heart rate variability in ventricular fibrillation patients without significant structural heart disease

It has been shown that tilt and exercise elicit significant changes in autonomic activity in normal subjects and that submaximal exercise causes a greater reduction in heart rate variability (HRV) in animals susceptible to ventricular fibrillation (VF). Whether there is an abnormal HRV response to tilt and exercise in patients at risk of sudden cardiac death (SCD) remains unknown. Short-term HRV before and during passive tilt and exercise was studied in 12 survivors of out-of-hospital cardiac arrest with documented VF and compared with 12 age- and sex-matched normal controls. No patient had significant structural heart disease or left ventricular dysfunction. HRV was computed as total-frequency (TF, 0.01 to 1.00 Hz), low-frequency (LF, 0.04 to 0.15 Hz) and high-frequency (HF, 0.15 to 0.40 Hz) components. There was no significant difference between normal controls and SCD survivors in HRV before or during tilt or submaximal exercise testing. The HF component was significantly decreased during tilt compared with that in the supine position in both normal controls (5.85 +/- 0.61 vs 5.08 +/- 0.95 In(msec2), p = 0.005) and patients (5.58 +/- 1.49 versus 4.74 +/- 1.18 In(msec2), p = 0.003). There was again no significant change in the TF or LF components during tilt in either patients or controls. All frequency components were significantly decreased during submaximal exercise testing in both patients and controls. However, there was no significant difference in any of these tilt- and exercise-induced changes in HRV between normal controls and SCD survivors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Time and frequency domain analyses of heart rate variability during orthostatic stress in patients with neurally mediated syncope

The role of autonomic balance during upright tilt in patients with neurally mediated syncope is unclear. To assess the characteristics of autonomic tone during orthostatic stress, 15 patients (mean age 32 years) with recurrent episodes of syncope (> or = 2) and a positive response to a 30-minute 60 degrees upright tilt were compared with the following control groups: (1) 15 patients (mean age 33.5 years) with > or = 2 episodes of recurrent syncope and a negative tilt response, and (2) 15 age- and sex-matched healthy volunteers (mean age 34 years) with no previous history of presyncope or syncope. Time domain measurements assessed were mean RR interval, standard deviation of normal RR intervals, and percentage of normal consecutive RR intervals differing by > 50 ms. Frequency domain measurements of the low-frequency (LF) and high-frequency (HF) bands were obtained, and the LF/HF ratio was also calculated. All variables were calculated in the supine position and during the first 5 minutes of upright tilt. No significant difference was observed in the time and frequency domain variables in the supine position between control groups with a negative head-up tilt response and the group with a positive response. The percentage of normal consecutive RR intervals differing by > 50 ms during the first 5 minutes of head-up tilt was significantly higher in the group with positive tilt tests than in the controls (25 +/- 12% vs 7 +/- 4%, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Tidal volume measurements in newborns using respiratory inductive plethysmography

Respiratory inductive plethysmography (RIP) is a well-accepted noninvasive technology for monitoring breathing patterns in adults. Prior attempts to calibrate this device in babies have been fraught with technical difficulties, thereby limiting applications in this population. Recently, a new method, qualitative diagnostic calibration (QDC), has been shown to provide accurate calibration of tidal volume in adults. The QDC method is based upon principles of the isovolume maneuver and carried out during natural breathing without specialized respiratory maneuvers or postural changes. We calibrated RIP with QDC in the supine posture and compared tidal volume (VT) measured with RIP to VT by a face mask-pneumotachograph (PNT) in 21 healthy full-term newborns in supine and prone postures. Eleven of the babies were calibrated during active sleep and 10 in quiet sleep. The mean VT in the supine and prone postures were 19 and 25 ml, respectively. In the supine and prone postures, weighted mean difference between RIP (VT) and PNT (VT) and 95% confidence intervals were -0.05 ml (-0.27, 0.18) and -0.32 ml (-0.08, 0.55), respectively. There was no difference in the accuracy of RIP relative to PNT calibrated during active sleep when thoracoabdominal incoordination was present or quiet sleep when it was not in either the supine or the prone postures. Therefore, in full-term infants, RIP calibrated with QDC solely in the supine posture provides clinically acceptable measurements of VT in both supine and prone postures.     

A 30-year-old woman with headache

Recent studies have reported a close association between chronic fatigue syndrome and neurally mediated hypotension. We hypothesized that this association may result from an abnormality in autonomic function among patients with chronic fatigue syndrome, which may be detectable using an analysis of heart rate variability. We prospectively studied 19 patients who fulfilled the Centers for Disease Control criteria for chronic fatigue syndrome and 11 controls. Each subject underwent a two-stage tilt-table test while wearing a Holter monitor. Heart rate variability was assessed in the supine baseline position and during upright tilt using frequency domain parameters. In the baseline supine position, high frequency (HF) power, low frequency (LF) power, and the ratio of low frequency power to high frequency power (LF/HF ratio) were similar. In both patient groups, upright tilt resulted in a similar decrease in HF power, increase in LF power, and increase in the LH/HF ratio. In conclusion, autonomic function, as assessed using an analysis of heart rate variability, does not differ in the baseline supine state, nor in response to upright tilt among patients with chronic fatigue syndrome and healthy controls.     

Oscillatory dynamics of smallpox and the impact of vaccination

In order to evaluate autonomic regulation in Parkinson's disease, the heart-rate responses to passive head-up tilt and the spectral analysis of spontaneous heart rate variability in supine position were studied in 18 young (30.8 +/- 1.38 years old) and 13 aged (61.9 +/- 1.61 years) healthy controls and 13 patients with Parkinson's disease (62.9 +/- 1.55 years). Patients were evaluated in the University Hospital of the Canary Islands by a neurologist and a specialist in rehabilitation. Finally, a computerized procedure developed in the Dept. of Physiology of La Laguna University was used to quantify the autonomic regulation of heart-rate (HR) variability. In relation to the younger group, elderly controls showed a reduction in the amplitude and no differences in the latency of the three successive peaks of HR response to tilt. In relation to the elderly matched controls, the Parkinson group showed a slight decrease for the second response amplitude and no differences for both the first or third response amplitude and the latency of the three responses. In the frequency domain analysis of the spontaneous HR oscillation in supine position recording, the elderly and Parkinson groups showed a decrease in the power spectrum for low frequency (<0.04Hz; thermoregulation related band), mid frequency (0.04-0.15Hz; related to sympathetic activity in response to baroreceptors stimulation) and high frequency (0.15-0.4Hz; related to sympathovagal tonus activated by respiratory movements). In relation to elderly controls, the Parkinson group showed lower power in the three spectral bands studied. Present data support the hypothesis that both sympathetic and parasympathetic control of heart activity are impaired in Parkinson's disease and that this dysfunction can be assessed by combining time-domain and frequency-domain analysis of HR changes.     

Sleeping position, orientation, and proximity in bedsharing infants and mothers

The impact of mother-infant bedsharing on infant sleeping position, orientation, and proximity to the mother was assessed in 12 breast-feeding Latino mother-infant pairs. Six routinely bedsharing and six routinely solitary-sleeping pairs slept 3 nights in the sleep laboratory. The first night matched the routine home condition, followed by 1 bedsharing night and 1 solitary-sleeping night in random order. During bedsharing infants were never placed prone, regardless of their routine sleeping condition. On the bedsharing night, mothers and infants spent most of the night oriented toward each other; seven of 12 infants remained oriented toward their mothers the entire night. While sleeping in a face-to-face orientation, most pairs slept most of the time less than 30 cm apart with appreciable amounts of time at less than 20 cm. This orientation and proximity should facilitate sensory exchanges between mother and infant which, we hypothesize, influence the infant's sleep physiology and nocturnal behavior. We conclude that bedsharing minimizes the use of the prone infant sleeping position, probably in part to facilitate breast feeding. By promoting nonprone positions, bedsharing may protect some infants from sudden infant death syndrome (SIDS), since prone sleeping is a known risk factor for SIDS. The large percentage of the night that mothers spent oriented toward their infants suggests that a higher degree of maternal vigilance may also result from bedsharing.     

Cardiac asystole post-exercise: a report of two cases

Two patients are described with reproducible cardiac asystole post-exercise. No structural heart disease was demonstrable. At autonomic function testing no abnormal responses were noted. Also, head-up tilt tests were normal. However, electrophysiologic testing and heart rate variability during 24-h Holter monitoring were indicative of a high vagal tone in both patients. The findings suggest that post-exertional asystole may not be due solely to a vasovagal mechanism; excessive rebound vagotonia per se may also play a role.     

Clinical and laboratory indices that enhance the diagnosis of postural tachycardia syndrome

OBJECTIVE: To identify clinical and laboratory indices that improve the diagnosis of the postural tachycardia syndrome (POTS). DESIGN: We assessed associations of orthostatic intolerance by using multivariate regression analysis. MATERIAL AND METHODS: We evaluated autonomic symptoms and autonomic function in 30 patients with POTS, 30 patients with mild orthostatic intolerance, and 19 age- and gender-matched control subjects. Indices of parasympathetic and sympathetic functions were analyzed on the basis of (1) autonomic function tests (head-up tilt), (2) oscillations at respiratory and nonrespiratory frequencies (0.01 to 0.09 Hz) in R-R interval and blood pressure (Wigner distribution), and (3) deterministic component (rescaled range analysis). RESULTS: The four clinical and laboratory indices that independently supported the diagnosis of POTS are as follows: (1) orthostatic heart rate during the first minute of head-up tilt, (2) autonomic deficit (adrenergic autonomic score), (3) loss of spectral powers in R-R interval during head-up tilt at the fifth minute, and (4) severity of orthostatic dizziness, fatigue, palpitations, and shortness of breath. CONCLUSION: Enhancing the sensitivity and specificity of the diagnosis of POTS should be possible by using these four indices. A hyperadrenergic state and distal neuropathy, affecting adrenergic sympathetic cardiovagal fibers, seem to be involved in the pathophysiology of POTS. Certain features suggest brain-stem dysregulation.     

Effect of heartbeat sound on the cardiac and behavioral responsiveness to tactual stimulation in sleeping preterm infants.

Assessed the effect of heartbeat sound on the heart rate and motor responses evoked by tactual stimulation during sleep. 30 preterm infants, 15 of whom had participated in a long-term intervention program, were tested one day in the presence of sound and another day in the absence of sound. During active sleep, the nonintervened Ss showed a significant cardiac response only in the presence of heartbeat sound. In this sleep state the sound also improved the discernibility of the motor responses for both groups of Ss by reducing spontaneous motor movements. During quiet sleep the sound had no effect on either cardiac or motor responsivity. Additionally, the sound influenced the duration of sleep states for both groups by markedly decreasing the duration of the lengthy 1st active sleep epoch and increasing the duration of the 1st quiet sleep epoch. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhythms in the central nervous system and 1/f fluctuations of the heart rate

We have developed a system to analyze heart rate variability (HRV) (power spectral array of the HRV) during 24 h ambulatory electrocardiographic monitoring. Several rhythms (circadian and several ultradian rhythms) were observed in the power spectral array of the heart rates and 1/f-like fluctuations in the log-log scaled heart rate power spectrum. The circadian change of the heart rate is closely related to the body temperature rhythm. The 90 min rhythm of HRV during sleep was suspected to be produced by the sleep cycle (REM/NREM) and the lower frequency peak of the HRV was coherent with oscillation in amplitude modulated respiration. These circadian and ultradian rhythm as assessed by heart rate variability exist both in normal subjects and in patients with autonomic failure. The power of the high frequency band decreases in subjects with autonomic failure. The power of low frequency components increases during periodic breathing or Cheyne-Stokes respiration. Log-log scaled analysis of the power spectrum of HRV disclosed that the slope of the HRV is markedly modulated by the range of the frequency applied for the least square regression line analysis. The increased power that might be produced by periodic breathing and decreased power in patients with autonomic failure might strongly modulate the slope of the log-log scaled HRV. It is concluded that the power spectral array of the HRV during 24 h period is useful in the detection of circadian and ultradian rhythm, and log-log scaled power spectra might be useful in the overall integration of the heart rate dynamics produced by the central nervous system. The several rhythm factors that might be produced by the central nervous system might modulate 1/f fluctuations of the HRV.     

Characteristics of the infant arousal response

Arousal is considered to be an important response to a life-threatening stimulus. Recently, it has been shown that the infant arousal response to an elevated inspired CO2 level occurs as a sequence of events involving presumptive brain stem responses before awakening (A. Lijowska, N. Reed, B. Chiodini, and B. T. Thach. Am. J. Respir. Crit. Care Med. 151: A151, 1995; A. S. Lijowska, N. W. Reed, B. A. Mertins Chiodini, and B. T. Thach. J. Appl. Physiol. 83: 219-228, 1997). We wanted to further evaluate the relationship of subcortical reflexes to cortical arousal in infants. We used a nonrespiratory (tactile) stimulus to elicit arousal in infants during non-rapid-eye-movement (NREM) and rapid-eye-movement (REM) sleep. We found that a tactile stimulus elicited an arousal sequence that commenced with a spinal withdrawal reflex, was followed by brain stem responses (respiratory and startle responses), and ended in a cortical arousal. The entire pathway or part of it in the order of spinal to cortical responses could be elicited. REM and NREM responses were similar except for significant differences in the latencies of spinal and subcortical reflexes. These observations suggest that the infant arousal response to a tactile stimulus involves a progression of central nervous system activation from the spinal to cortical levels. The different components of the arousal pathway may be important for an infant to respond appropriately to stimuli during sleep without necessarily disturbing sleep.     

Postprandial hypotension and orthostatic blood pressure responses in elderly Parkinson's disease patients

OBJECTIVE: To investigate the change in systolic blood pressure (SBP) induced by meals and to compare their impact on the orthostatic SBP response in elderly Parkinson's disease with that in control patients. DESIGN: Ten elderly patients suffering from Parkinson's disease were compared with 10 age-matched elderly control patients. METHODS: The postprandial SBP change was measured by means of ambulatory blood pressure monitoring with the patient in the supine position. Orthostatic SBP responses were measured the next day by means of active standing and passive head-up tilting tests performed before and after the patients had their lunch. RESULTS: In Parkinson's disease patients, a postprandial SBP drop of 27 mmHg in the supine position was found compared with a drop of 8 mmHg in controls. In Parkinson's disease patients, that drop was moderately correlated to the orthostatic SBP responses and significantly correlated to the preprandial supine baseline SBP level. The orthostatic fall in SBP was greater with passive than with active standing and with both it was greater in Parkinson's disease patients than in the control subjects. The fall in orthostatic blood pressure was reduced by a previous meal. In contrast, there was no difference in orthostatic heart rate responses between the patients and the controls. CONCLUSIONS: Parkinson's disease patients demonstrated a significant postprandial drop in SBP and a tendency towards orthostatic hypotension, which was not worsened by the meal, probably owing to a stronger sympathetic activation. Postprandial supine SBP change and orthostatic SBP responses were only moderately associated in Parkinson's disease patients. In addition to autonomic dysfunction, an increased baseline SBP level might contribute to both phenomena.     

Sequential arousal and airway-defensive behavior of infants in asphyxial sleep environments

Infants are prone to accidental asphyxiation. Therefore, we studied airway-defensive behaviors and their relationship to spontaneous arousal behavior in 41 healthy sleeping infants (2-26 wk old), using two protocols: 1) infant was rebreathing expired air, face covered by bedding material; and 2) infant was exposed to hypercarbia, face uncovered. Multiple measurements of respiratory and motor activities were recorded (video, polygraph). The infants' response to increasing hypercarbia consisted of four highly stereotyped behaviors: sighs (augmented breaths), startles, thrashing limb movements, and full arousal (eyes open, cry). These behaviors occurred abruptly in self-limited clusters of activity and always in the same sequence: first a sigh coupled with a startle, then thrashing, then full arousal. Incomplete sequences (initial behaviors only) occurred far more frequently than the complete sequence and were variably effective in removing the bedding covering the airway. In both protocols, as inspired CO2 increased, incomplete arousal sequences recurred periodically and with increasing frequency and complexity until the infant either succeeded in clearing his/her airway or was completely aroused. Spontaneous arousal sequences, identical to those occurring during hypercarbia, occurred periodically during sleep. This observation suggests that the infant's airway-defensive responses to hypercarbia consist of an increase in the frequency and complexity of an endogenously regulated, periodically occurring sequence of arousal behaviors.     

Auditory steady-state response to sinusoidally amplitude-modulated tones. Second report: investigation of response in the sleeping state

The auditory steady state response (SSR) elicited by a sinusoidally amplitude-modulated (SAM) tone may be an important technique in objective audiometry, which provides frequency-specific information. This response is affected the state of arousal of the subject. An effect of sleep on the amplitude of this response has been observed by a number of previous investigators. Since young children must usually be sedated to carry out evoked potential testing, the effects of sleep on this response are a crucial factor limiting clinical applicability. The basic characteristics of SSR elicited by a 500 Hz SAM tone were studied in 21 adults with normal hearing during sleep. The responses while sleeping were compared with the responses in the awake state. The responses to 2048 stimuli were averaged with the analysis time set at 102.4 ms, and responses were judged by passing the waveforms through a 20-100 Hz digital filter. The same technique was performed in 25 infants (2 months-2 years 9 months) evaluated as having normal hearing. The results obtained are summarized as follows: The amplitude of the response while sleeping was approximately half the amplitude in the awake state. Responses with a modulation frequency of 70Hz, however, showed a persistent decrease in 71.0%, suggesting a trend different from that seen at a modulation frequency of less than 70Hz. The effect of modulation frequency on response amplitude was almost the same for the sleeping state and the awake state. Even during sleep, the response amplitude was maximal at modulation frequencies of 20, 30 and 40Hz, and there was no significant difference between the values at 20Hz -40Hz. The latency of the response was measured by the Diamond method, and the results showed that latency is significantly prolonged while sleeping (p < 0.01). The response threshold at the 500Hz SAM tone (modulation rate 40Hz, modulation depth 90%) was 8.5dBnHL when awake and 13.9dBnHL during sleep. The rise in threshold as a result of sleep was no more than about 5dB. In infants, the response amplitude at a modulation frequency of 20Hz was maximal, and amplitude at the 40Hz was significantly smaller (p < 0.01). Latency measured by the Diamond method in infants was 12.8ms. Thus, a difference from the response in adults was confirmed. Comparisons were made between the responses of infants under 1 year of age and infants over 1 year of age to confirm changes in response according to age.     

Cerebrovascular and cardiovascular responses to graded tilt in patients with autonomic failure

BACKGROUND AND PURPOSE: Patients with autonomic nervous system failure often experience symptoms of orthostatic intolerance while standing. It is not known whether these episodes are caused primarily by a reduced ability to regulate arterial blood pressure or whether changes in cerebral autoregulation may also be implicated. METHODS: Eleven patients and eight healthy age- and sex-matched control subjects were studied during a graded-tilt protocol. Changes in their steady state middle cerebral artery mean flow velocities (MFV), measured by transcranial Doppler, brain-level mean arterial blood pressures (MABPbrain), and the relationship between the two were assessed. RESULTS: Significant differences between patients and control subjects (P < .05) were found in both their MFV and MABPbrain responses to tilt. Patients' MFV dropped from 60 +/- 10.2 cm/s in the supine position to 44 +/- 14.0 cm/s at 60 degrees head-up tilt, whereas MABPbrain fell from 109 +/- 11.7 to 42 +/- 16.9 mm Hg. By comparison, controls' MFV dropped from 54 +/- 7.8 cm/s supine to 51 +/- 8.8 cm/s at 60 degrees, whereas MABPbrain went from 90 +/- 11.2 to 67 +/- 8.2 mm Hg. Linear regression showed no significant difference in the MFV-MABPbrain relationship between patients and control subjects, with slopes of 0.228 +/- 0.09 cm.s-1.mm Hg-1 for patients and 0.136 +/- 0.16 cm.s-1.mm Hg-1 for control subjects. CONCLUSIONS: The present study found significant differences between patients and control subjects in their MFV and MABPbrain responses to tilt but no difference in the autoregulatory MFV-MABPbrain relationship. These results suggest that patients' decreased orthostatic tolerance may primarily be the result of impaired blood pressure regulation rather than a deficiency in cerebral autoregulation.     

Effects of age and isolated systolic hypertension on cardiovascular reflexes

OBJECTIVES: Given the reported relationship between systolic hypertension and orthostatic hypotension in the elderly, to test the hypothesis that systolic hypertension causes impairment of the cardiovascular reflex function additional to the effects of age alone. DESIGN: Responses were compared in normotensive healthy young (n = 12) and elderly (n = 15) participants and elderly participants with disproportionate supine systolic hypertension (n = 11) using a baroreceptor-mediated stress (head-up tilt) and two non-baroreceptor-mediated stimuli (cold pressor test and isometric exercise). METHODS: Blood pressure and heart rate were measured by oscillometry before and during the three stress tests. Forearm blood flow was measured by venous occlusion plethysmography and pulse wave velocity (PWV) by Doppler ultrasound. RESULTS: Percentage changes in systolic/diastolic (SBP/DBP) blood pressure with head-up tilt were 0/+11, -3/0 and -6/+1 mmHg in the young and elderly normotensives and elderly systolic hypertensives, respectively. Both elderly groups had reduced DBP responses to tilt compared with the young (P < 0.01). All three groups had similar percentage changes in blood pressure responses to non-baroreflex-mediated stresses (cold pressor test: +10/+23, +11/+11, +10/+15; sustained isometric exercise: +18/+33, +22/+24, +13/+17 in the young and elderly normotensives and elderly systolic hypertensives, respectively). Aorto-iliac PWV adjusted for blood pressure was significantly higher in both elderly groups compared with the young (P < 0.01) but there was no difference between elderly normotensives and hypertensives. Unadjusted PWV was higher in elderly hypertensives than in elderly normotensives (P < 0.05). CONCLUSIONS: Compared with healthy young participants, both elderly groups had similarly attenuated blood pressure responses to tilt and reduced arterial compliance. Systolic hypertension is not associated with additional impairment of cardiovascular reflex function over and above the effects of age. The reported association between supine systolic hypertension and orthostatic hypotension does not appear to be a causative one.