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PubMed1981

Influence of initial posture on posturo-kinetic co-ordination in the cat.

The influence of postural support on posturo-kinetic co-ordination has been studied with a model of movement consisting of limb flexion induced by stimulation of the motor cortex in chronically implanted cats. To more easily quantify the responses by measuring the vertical forces exerted at the level of the four limbs, only weak stimuli were used, mainly triggering isometric motor activity. The aim of the study was to analyse the influence on the motor responses of various postural supports leading to a weight distribution between the limbs which differs from the normal situation. Three kinds of initial posture were tested. The first was obtained by directing the head of the cat to the left or to the right. The second type consisted in raising one or two of the platforms supporting the limbs. The third was obtained by adding a load to one of the limbs. The main results established in these conditions were the following: The latencies of the beginning of the movement and its associated postural adjustment, as revealed by the onset of force changes, were independent of the initial postural situation. Whatever the initial weight distribution, the amplitudes of force variations induced by given intensities of cortical stimulation were generally constant, though small variations of amplitude were noted in some cases. When there were changes in the response amplitudes, all four limbs were generally affected. The effect was observed whatever the limb concerned by modification of the support. This not only means that the postural responses depend on the amplitude of the movement but also that the amplitude of the movement itself may be modified according to perturbations affecting the postural limbs. Comparison of the present data with previous results leads to the hypothesis that a postural reference is taken into account in the determination of amplitudes of responses to cortical stimulation.

Animals↗

PubMed1988

Postural adjustments associated with voluntary contraction of leg muscles in standing man.

The postural adjustments associated with a voluntary contraction of the postural muscles themselves have been studied in the legs of normal standing men. We focussed on the following questions. Do postural adjustments precede the focal movement as in the case of movements of the upper limb? Which muscle(s) are involved in the task of stabilizing posture? Can the same postural muscle be activated in postural stabilization and in voluntary movement at the same time, in spite of the opposite changes in activity possibly required by these conditions? Six subjects standing on a dynamometric platform were asked to rise onto the tips their toes by contracting their soleus muscles, or to rock on their heels by contracting their tibialis anterior muscles. The tasks were made in a reaction time (RT) situation or in a self-paced mode, standing either freely or holding onto a stable structure. Surface EMGs of leg and thigh muscles, and the foot-floor reaction forces were recorded. The following results were obtained in the RT mode, standing freely. 1. Rising onto toe tips: a striking silent period in soleus preceded its voluntary activation; during this silent period, a tibialis anterior burst could be observed in three subjects; these anticipatory activities induced a forward sway, as monitored by a change in the force exerted along the x axis of the platform. 2. Rocking on heels: an enhancement in tonic EMG of soleus was observed before tibialis anterior voluntary burst, at a mean latency from the go-signal similar to that of the silent period; this anticipatory activity induced a backward body sway. 3. Choice RT conditions showed that the above anticipatory patterns in muscle activity were pre-programmed, specific for the intended tasks, and closely associated with the focal movement. When both tasks were performed in a self-paced mode, all the above EMG and mechanical features were more pronounced and unfolded in time. If the subjects held onto the frame, the early features in the soleus or tibialis anterior EMG were absent, and the corresponding changes in the foot-floor reaction forces were lacking. The anticipatory phenomena observed are considered postural adjustments because they appear only in the free-standing situation, and induce a body sway in the appropriate direction to counteract the destabilizing thrust due to the voluntary contraction of soleus or tibialis anterior. The central organization and descending control of posture and movements are briefly discussed in the light of the short latency of the anticipatory phenomena and of their close association with the focal movement.

Adult↗

PubMed1997

Automatic control of postural sway by visual motion parallax.

The purpose of this study was to establish whether visual motion parallax participates in the control of postural sway. Body sway was measured in ten normal subjects by photoelectric recordings of head movements and by force-plate posturography. Subjects viewed a visual display ("background"), which briefly moved (2 s) along the y (horizontal) axis, under three different conditions: (1) direct fixation of the background, (2) fixation of a stationary window frame in the foreground, and (3) fixation of the background in the presence of the window in the foreground ("through the window"). In response to background fixation, subjects swayed in the same direction as stimulus motion, but during foreground (window) fixation they swayed in the opposite direction. The earlier forces observed on the force platform occurred at circa 250 ms in both conditions. The results show that motion parallax generates postural responses. The direction of these parallax-evoked postural responses-opposite to other visually evoked postural responses reported so far-is appropriate for stabilizating posture in natural circumstances. The findings show that motion parallax is an important source of self-motion information and that this information participates in the process of automatic postural control. In the "fixating through the window" condition, which does not mimic visual conditions induced by body sway, no consistent postural responses were elicited. This implies that postural reactions elicited by visual motion are not rigid responses to optokinetic stimulation but responses to visual stimuli signalling self-motion.

Adult↗

PubMed2006

Age-dependent differences in the time course of postural control during sensory perturbations.

BACKGROUND AND AIMS: With research demonstrating that older adults are more likely to sustain a loss of balance than younger adults, the need for an account of age-related differences in postural control is apparent. Several measures of balance reported in the literature have assessed balance using an average or summative measure over the course of a trial, typically lasting several seconds. One limitation related to these measures is the inability to assess the time-course of postural control occurring throughout the trial. To this end, the current investigation assessed the temporal changes in balance both as a function of age and sensory environment. METHODS: Postural control was assessed from 10 older adults (69.3+/-4.7 years) and 10 younger adults (22.1+/-1.7 years) over the course of fifteen seconds in three different sensory environments. The sensory manipulations involved sway-referenced rotation of the floor and/or the visual surround. RESULTS: Significant differences (p=0.001) in overall postural stability were observed between the two groups on all three sensory conditions. Additionally, time-course changes were observed between the two groups when the environment did not cause sensory conflict (sway-referenced floor or room only). However, when the environment created a situation of sensory conflict (sway-referenced floor and room) both groups followed the same time-course of postural changes. CONCLUSIONS: Interestingly, the time course of postural control for the older adults on the easiest condition was mimicked by the younger adults on a more challenging condition. However, when faced with sensory conflict there were no group differences in the time course of postural control. The findings suggest an age-related decline in the temporal control of posture in altered sensory environments.

Accidental Falls↗

PubMed2005

Comparison of postural control in unilateral stance between healthy controls and lumbar discectomy patients with and without pain.

MAIN PROBLEM: Previous studies have demonstrated that sciatica patients have poorer postural control than healthy controls and that postural control remains unchanged 3 months after lumbar discectomy in sciatica patients. The aims of the current study were to investigate whether static balance control recovers in pain-free discectomy patients long-term after lumbar discectomy. Next is to determine whether static balance responses of asymptomatic and symptomatic lumbar discectomy patients differed from each other and from healthy controls. In addition, the influence of the extent of disc resection (unilateral/bilateral removal) and the side of operation on static balance control were investigated. METHODS: Fifteen pain-free lumbar discectomy patients, 23 lumbar discectomy patients with residual pain and 72 controls performed unilateral stance tasks with eyes open and eyes closed on a force plate were taken up for the investigation. Three repetitions of a 10 s unilateral stance test were performed on each leg. Postural sway was determined. Patients were divided into three age groups. RESULTS: In the eyes open condition, there was no significant difference between postural sway of pain-free lumbar discectomy patients and controls (P=0.68), whereas balance of patients with pain was significantly worse than in controls (P=0.003). In the eyes closed condition, the sway in both groups of lumbar discectomy patients was significantly worse than in controls (pain-free P=0.009/painful P<0.001). No significant differences were found in postural sway between patients with unilateral and bilateral disc resection. In unilateral stance on the leg of the operated side, centre of gravity sway was not significantly different in the eyes open condition compared to the eyes closed condition, whereas in stance on the leg of the non-operated side, postural sway was significantly lower in the eyes open condition compared to the eyes closed condition. In both conditions, postural sway in the age group of 50-65 years was significantly higher than in the age groups of 30-39 years (eyes open P=0.005; eyes closed P<0.001) and 40-49 years (eyes open P=0.002; eyes closed P=0.006). There was no significant difference between the age group of 30-39 years and the age group of 40-49 years (P=0.51). CONCLUSION: As for long-term following lumbar discectomy, there is no complete recovery of postural control. Patients seem to develop visual compensation mechanisms for underlying sensory-motor deficits, which are, however, sufficient in case of pain relief only. Further study is needed to determine the cause of the balance disturbances in lumbar discectomy patients.

Adult↗

PubMed1980

Morphine versus haloperidol catalepsy in the rat: a behavioral analysis of postural support mechanisms.

Our experiments demonstrate that morphine and haloperidol produce two distinct and contrasting behavioral states, which can be thought of as exaggerated, isolated, and simplified forms of organized adaptive behavioral states functioning as components of normal motivated behavior. Haloperidol catalepsy constitutes an organized state in which tonic reactions subserving the maintenance of stable static equilibrium prevail, at the expense of phasic locomotor reactions. In contrast, morphine produces an immobility state characterized by inhibition of the postural support subsystem, and compatible with or preparatory to locomotor rather than static postural reactions. haloperidol-treated rats (1, 2.5, 5, 10 mg/kg i.p.) display exaggeraged bracing reactions to passive displacement as well as to stimuli which do not actively challenge stable equilibrium. In contrast, rats treated with morphine sulfate (10, 20, 40, 80 mg/kg i.p.) show a dose-dependent suppression of bracing and an exaggerated tendency to run in response to stimuli which produce bracing in haloperidol-treated rats. Further evidence that haloperidol-treated rats are organized to stand still in stable equilibrium includes their typical posture during akinesia (i.e. broad-based support), bradykinesia, tonic grasping and enhanced postural components of contact- and air-righting. Under morphine, however, the postural support subsystem is dispensed with, as evidenced by the posture of akinesia (i.e. a frozen phase of the locomotor step cycle associated with loss of limb support), absence of tonic grasping, and nature of the deficits in contact- and air-righting. Furthermore, the opiate-induced immobility state is accompanied by an increased readiness to locomote. Morphine produces an alternation between two extreme behavioral states: complete immobility (inhibition of the postural support subsystem) versus locomotor paroxysms (varying degrees of 'explosive motor behavior'). We suggest that the postures or actions adopted by morphine-treated rats involve movement subsystems concerned with the adaptive behavioral state known as the 'immobility reflex' ('tonic immobility', 'animal hypnosis').

Animals↗

PubMed1987

Integration of posture and locomotion in acute decerebrate cats and in awake, freely moving cats.

For the past 10 years, our group has been engaged in the study of posture and locomotion in decerebrate cats and in freely moving awake cats. Our initial objective was to analyse the neuronal mechanisms of locomotion from a viewpoint of "postural control". Therefore, in this review, I have focussed my attention on two major control aspects of the brain stem; one related to the interaction of posture and locomotion; and the other to initiation of locomotion. It is apparent that elucidation of the second aspect is feasible. In Fig. 15, I have summarized all the neuronal structures that have been functionally identified as being actively involved in the regulation of posture and locomotion. Obviously, contribution of the cerebello-cerebral pathways and the basal ganglia to both the postural and to the locomotor control cannot be elucidated in decerebrate preparations (Fig. 15A). These contributions can, to a certain degree, be elucidated in intact awake cats (Fig. 15B). Although it is difficult to directly compare the results obtained in the decerebrate cats with those obtained in intact cats, it has been encouraging that the selective activation of certain neuronal structures within the brain stem allowed us to evoke comparable postural and locomotor changes in both groups of preparations. It can be expected that the knowledge obtained from studies of the cerebello-cerebral pathways and of the basal ganglia, together with those that can be further obtained from studies of the brain stem, should result in the elucidation of the two major control aspects of the brain stem described above. In this sense, both the models of the decerebrate locomotor preparation and the freely moving, awake cat seem to provide an unique opportunity to study the nature and the sources of command signals that set the postural and the locomotor synergies into a single functional synergy, and even to approach elucidation of the intriguing question as to how and where volitional control signals for initiating and/or halting locomotion are organized. More than 70 years have passed since the pioneer studies by Sherrington (1906) and by Graham Brown (1911, 1914) on postural control and on locomotion, as exemplified by "decerebrate reflex standing, and stepping" and the "central rhythmic generator" relating to locomotion. Based on these discoveries, Shik, Severin and Orlovsky (1966) have made a splendid breakthrough in a wide area of investigation relating to locomotion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Posture and spontaneous motility in fullterm infants.

Posture and spontaneous motor patterns during the first days of life were studied in ten healthy fullterm infants by direct observation and videorecording. The aim of the study was to provide a description of motor and postural characteristics of normal newborns. The infants were recorded for 1 h on their first and fourth day of life, when unstimulated in an incubator. Incidence and duration of the different body postures and motor patterns were scored during the replay of the videorecordings. The preference for the fully flexed posture of arms and legs described in the literature could not be confirmed. There was a large intra- and inter-individual variability in the postural repertoire. No particular posture, characteristic for each behavioural state, existed. Similar postures rarely occurred in the same infant on the first and fourth day. Extended postures more often occurred on the fourth day. Spontaneous motility consisted of several distinct movement patterns, the occurrence of which in states 1 and 2 was computed for day 1 and day 4. Motor patterns were differently related to the states. No differences were noted in the motor activity between the first and fourth days. Large inter-individual differences, but an intra-individual consistency, were found in the rates of specific motor patterns: infants who showed a low or high rate of particular movements on day 1 maintained the same characteristic on day 4. There was no overall low or high motor activity.

Female↗

PubMedDate not supplied

Posture in low-risk pre-term infants of 30 weeks postmenstrual age.

In this study we analysed the spontaneous postural behaviour of seven pre-term infants of 30 weeks postmenstrual age (PMA). Each infant was observed for a 3-h observation period and each minute a sketch of the resting-posture was made. Analysis of the postures included the complete observed posture, the distribution of adduction and abduction of the hips and shoulders and the distribution of extension and flexion of the elbows and knees. Although each infant showed a preference posture, no preference posture for the total group could be determined. A separate analysis of the positions of the limbs showed a preference for fully flexed arms and partly extended legs. Because no group preference posture at 30 weeks PMA (nor at other PMA in different studies) could be determined, it is suggested that the use of posture as a characteristic of PMA is no longer warranted.

Extremities↗

PubMed2004

Monocular versus binocular vision in postural control.

OBJECTIVE: In previous studies about the control of posture there have been controversial findings. Our aim was to examine the role of monocular and binocular vision in controlling posture in quiet stance. METHODS: Twenty-eight normal subjects were tested. We used a force platform in measuring postural stability. In main experiment, postural stability was measured in four conditions: both eyes open (BEO), dominant eye open (DEO) non-dominant eye open (NDEO), and both eyes closed (BEC). In a further experiment, 11 subjects were tested in conditions where a vertical prism was placed in front of dominant eye. Prism was strong enough to cause diplopia. Our interest was to see, if diplopia affected the balance. RESULTS: In main experiment, at level of group the body-sway in any of the three ocular (viewing) conditions did not differ from each other. At level of individuals, binocular vision was more effective on controlling posture in only half of subjects. In prism experiment, relative to normal binocular viewing the postural stability was modified in both prism conditions, but there was no difference between monocular and binocular viewing with prism. CONCLUSION: In quiet stance and in subjects with perfect binocular vision and stereopsis, the benefit out of binocular viewing in postural stability is subject-dependent. At the level of group, monocular vision provides equally good postural stability as binocular vision.

Adult↗

PubMed2006

Comparison of stoop versus prone postures for a simulated agricultural harvesting task.

Physical and psychophysical differences between working in the stooped and prone postures were compared while performing a simulated agricultural harvesting task for 30 min. Fifteen male subjects participated. The measures used to compare the two postures included perceived discomfort, electromyography (EMG), and heart rate (HR). Average hamstrings localized discomfort (0-10 scale) was 6.17 (SD=2.9) for the stoop posture and 0.67 (SD=1.29) for the prone posture. Erector spinae and hamstring EMG RMS increased 68% and 18%, respectively, while mean power frequency for the hamstrings decreased 13% for the stoop task. Mean power frequency for the middle trapezius muscle decreased in both postures (stoop 4.13%, prone 3.79%). Average heart rate during the last work cycle was 35% greater than the resting heart rate for the stoop posture while average heart rate was 17% greater for the prone posture. Subjects worked on the prone workstation without rest during the 15 min work simulations with less discomfort, no localized fatigue in the back or leg muscles tested, and lower working heart rates than subjects working in the stoop posture.

Adult↗

PubMed2004

Posture of the trunk in the sagittal plane is associated with gait in community-dwelling elderly population.

OBJECTIVES: The purpose of this study was to evaluate whether abnormal posture of the trunk in the sagittal plane would affect gait and functional performance in the elderly. BACKGROUND: There have been very few reports on whether posture of the trunk is related to gait and functional performance. METHODS: The study group included 237 participants with a mean age of 80.0 years (range 65-94 years). The posture of the trunk in a standing position of the sagittal plane was classified into five groups. We investigated the relationship between the trunk posture in the sagittal plane and age with gait parameters and functional performance such as timed up & go test and functional reach. RESULTS: In the elderly subjects of normal posture, there was no difference between those in the 65-79 years age group and those in the 80 years and older age group in terms of any gait parameters. Walking abilities were significantly decreased in the abnormal posture groups. Among the abnormal posture groups, elderly in the lumbar kyphosis group had walking disabilities that did not differ between age groups, whereas gait disturbance in the thoracic kyphosis group showed a positive relation with age. CONCLUSIONS: Posture of the trunk in the sagittal plane was associated not only with the distance and time parameter of gait, but also with functional performance in the elderly.

Aged↗

PubMed2006

Impact of finger posture on mapping from muscle activation to joint torque.

BACKGROUND: The mapping from muscle activation to joint torque production can be difficult to determine for the multi-articular muscles of the fingers. This relationship was examined in vivo as a function of posture in the index finger. METHODS: Five healthy adults participated in an experiment in which the seven muscles of the index finger were sequentially electrically stimulated using intramuscular electrodes. Each muscle was stimulated at 12 different finger postures consisting of specified flexion of the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints, while fingertip forces and moments were recorded. FINDINGS: Repeated measures analysis of variance revealed that joint torques resulting from the stimulation were significantly dependent upon finger posture (p < 0.05). The magnitude of the change in joint torque across postures was generally greater than 60%. This value is much larger than the difference attributable to the increase in active muscle force that occurs at longer muscle length, in accordance with the force-length curve (10-20% for the estimated length changes). In addition, the relative distribution of the joint torques generated by a given muscle activation was dependent upon finger posture for the intrinsic muscles and the long finger flexors (p < 0.05); the ratio of one joint torque to another varied with posture for these muscles, in some cases by more than 50%. INTERPRETATION: Joint torque is a product of both muscle force and the corresponding moment arm. As the change in active muscle force was limited, these data suggest that substantial changes in muscle moment arms occur with posture. Therefore, this postural dependence should be considered when constructing biomechanical models of the hand or planning tendon transfers for the fingers.

Adult↗

PubMed2005

Effect of posture on heart rate variability spectral measures in children and young adults with heart disease.

BACKGROUND: Reduction of heart rate variability as a consequence of heart disease and postural change has been well documented. However, the data on the effect of postural change in pediatric patients are incomplete and the effect is not fully understood. The aim of the study was to investigate effect of postural change on heart rate variability in relation to the extent of severity of heart disease. METHODS: The dependence of heart rate variability on posture in 41 children and young adults (8-20 years) with heart disease has been investigated and compared with control. Short-term electrocardiograms (ECGs) were assessed in supine rest and active standing, and spectral measures of heart rate variability were determined. RESULTS: Two types of response to the change of supine to standing posture were determined in both healthy and diseased subjects. In majority of subjects, the increased heart rate induced by standing was accompanied by a decrease in high-frequency power. However, in about 30% of all subjects, increased heart rate during standing was accompanied by an increased high-frequency power. Independently of posture and disease, high-frequency and low-frequency power were positively correlated. In subjects characterized by a reduction of heart rate variability in standing, the high-frequency power in both postures is reduced in diseased subjects compared to control. CONCLUSIONS: These results demonstrate that in this age range, the response to posture is not unique because of the difference in high-frequency power, which implies a variety of vagal modulations of heart rate.

Adolescent↗

PubMed2006

Biomechanical capabilities influence postural control strategies in the cat hindlimb.

During postural responses to perturbations, horizontal plane forces generated by the cat hindlimb are stereotypically directed either towards or away from the animal's center of mass, independent of perturbation direction. We used a static, three-dimensional musculoskeletal model of the hindlimb to investigate possible biomechanical determinants of this "force constraint strategy." We hypothesized that directions in which the hindlimb can produce large forces are preferentially used in postural control. We computed feasible force sets (FFSs) based on hindlimb configurations of three cats during postural equilibrium tasks and compared them to horizontal plane postural force directions. The grand mean FFS was bimodal, with maxima near the posterior-anterior axis (-86+/-8 degrees and 71+/-4 degrees ), and minima near the medial-lateral axis (177+/-8 degrees and 8+/-8 degrees ). Experimental postural force directions clustered near both maxima; there were no medial postural forces near the absolute minimum. However, the medians of the anterior and posterior postural force direction histograms in the right hindlimb were rotated counter-clockwise from the FFS maxima (p<0.05; Wilcoxon signed-rank test). Because the posterior-anterior alignment of the FFS is consistent with a hindlimb structure optimized for locomotion, we conclude that the biomechanical capabilities of the hindlimb strongly influence, but do not uniquely determine the force directions observed in the force constraint strategy. Forces used in postural control may reflect a balance between a neural preference for using forces in the directions of large feasible forces and other criteria, such as the stabilization of the center of mass, and muscular coordination strategies.

Animals↗

PubMed2006

Considerations for maintenance of postural alignment for voice production.

There is general agreement that postural alignment is important in optimizing voice function. A number of articles have illuminated the way in which posture, particularly of the cervical spine, is directly related to vocal resonance and pitch control. Despite frequent involvement in muscle training, few speech pathologists have the background in exercise physiology necessary to appreciate the contribution of muscular length-tension relationships to postural alignment. The purpose of this article is to provide voice therapists with information to help them formulate appropriate recommendations for improving postural alignment. This article synthesizes information from the literature regarding the role of muscular length-tension balance in the attainment and maintenance of postural alignment. Important considerations in the assessment of muscle tension and weakness are presented along with advice regarding application to the treatment of voice-disordered patients. Concepts detailed include agonist/antagonist relationships, the biomechanics of stretching, postural assessment, and the relationship between muscle tension and muscle weakness. The role of both stretching and strength-based training is discussed. Specific exercises with emphasis on altering the alignment of the cervical and thoracic spine are presented with suggestions for their use in the clinic. There is growing understanding of the physiology behind recommendations of voice teachers and therapists to maintain optimal alignment. To effectively mediate postural misalignment, clinicians must have knowledge of the length-tension relationships between muscles. This understanding will lead to better interventions for postural alignment.

Biomechanical Phenomena↗

PubMed2005

The relationship beween posture and back muscle endurance in industrial workers with flexion-related low back pain.

This preliminary cross-sectional study was undertaken to determine if there were measurable relationships between posture, back muscle endurance and low back pain (LBP) in industrial workers with a reported history of flexion strain injury and flexion pain provocation. Clinical reports state that subjects with flexion pain disorders of the lumbar spine commonly adopt passive flexed postures such as slump sitting and present with associated dysfunction of the spinal postural stabilising musculature. However, to date there is little empirical evidence to support that patients with back pain, posture their spines differently than pain-free subjects. Subjects included 21 healthy industrial workers and 24 industrial workers with flexion-provoked LBP. Lifestyle information, lumbo-pelvic posture in sitting, standing and lifting, and back muscle endurance were measured. LBP subjects had significantly reduced back muscle endurance (P < 0.01). LBP subjects sat with less hip flexion, (P = 0.05), suggesting increased posterior pelvic tilt in sitting. LBP subjects postured their spines significantly closer to their end of range lumbar flexion in 'usual' sitting than the healthy controls (P < 0.05). Correlations between increased time spent sitting, physical inactivity and poorer back muscle endurance were also identified. There were no significant differences found between the groups for the standing and lifting posture measures. These preliminary results support that a relationship may exist between flexed spinal postures, reduced back muscle endurance, physical inactivity and LBP in subjects with a history of flexion injury and pain.

Adult↗

PubMed2006

A modified postural drainage position produces less cardiovascular stress than a head-down position in patients with severe heart disease: a quasi-experimental study.

QUESTION: Does a modified postural drainage position (horizontal) produce less cardiovascular and respiratory stress than a head-down postural drainage position (30 degrees) in people with severe heart disease? DESIGN: A quasi-experimental study. PARTICIPANTS: Thirty-one patients (mean age 69 years, SD 13) with severe left ventricular systolic dysfunction (mean ejection fraction 23%, SD 7) who were stable, receiving regular medication and free of acute respiratory illness. INTERVENTION: Two manoeuvres were performed--one from long sitting to a modified (horizontal) postural drainage position, and one from long sitting to a head-down (30 degrees) postural drainage position. OUTCOME MEASURES: Cardiovascular responses examined were blood pressure, sphygmocardiographic indices, and cardiac rhythm. Respiratory responses examined were respiratory rate, transcutaneous arterial oxyyhaemoglobin saturation, and dyspnoea. RESULTS: Three participants were intolerant to the postural drainage positions--two during head-down and one during modified positioning. The remaining 28 participants maintained their resting cardiac rhythm and did not complain of chest pain or dyspnoea. The changes in cardiovascular responses during the sitting to head-down postural drainage manoeuvre in the tolerant participants were significantly greater (p < 0.05) than the changes during the sitting to the modified postural drainage manoeuvre for most of the sphygmocardiographic indices. In contrast, there were no significant respiratory responses to either postural drainage manoeuvre. CONCLUSION: Modified positioning is associated with less cardiovascular stress than head-down positioning, yet for most patients with severe heart disease, both positions are generally well tolerated. For a subset of these patients, either position may be inappropriate. This suggests that modified positioning should be attempted first but that a head-down position may be attempted if the modified position proves ineffective.

Aged↗