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E Dean

Publications and source records attributed to E Dean.

At least 19 recordsLinked to original sources
PubMed2002

Interrelationships between anxiety, lifestyle self-reports and fitness in a sample of Hong Kong University students.

Although anxiety in university students has been well documented, the influence of lifestyle and fitness status in relation to anxiety has not been investigated from a cultural perspective previously. To make recommendations regarding the avoidance or management of anxiety in this anxiety-prone cohort that are rationally based, this preliminary investigation examined the interrelationship between anxiety, lifestyle self-reports and aerobic fitness in Hong Kong Chinese University students. The State Trait Anxiety Inventory (Form Y-2) and a lifestyle questionnaire were completed by 213 students. Female students were more anxious than male students. Subjects with high anxiety reported more deleterious lifestyle behaviours including higher salt consumption and lower levels of exercise; in addition to more frequent symptoms of anxiety such as headaches and daytime somnolence. The extremes of this sample were stratified into a low anxiety group (n = 17) and a high anxiety group (n = 14) to compare their fitness status. Although both groups had below normal aerobic capacity, the higher systolic blood pressure observed for the high anxiety group is consistent with signs of anxiety, or greater deconditioning in this group or both. The results of this study have highlighted anxiety as a concern in Hong Kong University students and identified some lifestyle and fitness correlates. Understanding lifestyle and pathophysiological correlates of anxiety in Hong Kong University students that may have a cultural basis, is a crucial step toward averting or managing anxiety when these students are studying either in Hong Kong or abroad.

Adult↗
PubMed2001

Cardiovascular responses to repetitive McKenzie lumbar spine exercises.

BACKGROUND AND PURPOSE: Repetitive exercises of the type recommended by McKenzie for the lumbar spine, such as flexion and extension exercises in standing (FIS and EIS) and lying positions (FIL and EIL), have been used in the management of low back pain for over 20 years. The cardiovascular effects of exercises that involve postural stabilization and the arms and of exercises performed in a lying position are well known. Therefore, the purpose of this study was to examine the cardiovascular effects of 4 exercises used in the McKenzie system. SUBJECTS AND METHODS: One hundred subjects without cardiovascular or cardiopulmonary disease (mean age=31 years, SD=6.1, range=22-44) and who were representative of people susceptible to low back pain were studied. Subjects were randomly assigned to 1 of 4 exercise groups (ie, FIS, EIS, FIL, and EIL). Subjects performed sets of 10, 15, and 20 repetitions of the assigned exercise, with a 15-minute rest between sets. Heart rate, blood pressure, and rate-pressure product (an index of myocardial work) were recorded before and after each set of repetitions. RESULTS: After 10 repetitions, flexion and extension in lying were more hemodynamically demanding than in standing. This trend persisted for 15 and 20 repetitions; however, at 20 repetitions, the hemodynamic demands were different across exercise groups (ie, FIL>EIL>FIS>EIS). DISCUSSION AND CONCLUSION: Repetitive exercises of the type suggested by McKenzie for the lumbar spine can have cardiovascular effects in people with no cardiovascular or cardiopulmonary conditions. These effects may be important with respect to cardiac work, and patients for whom these exercises are indicated should have a cardiac and pulmonary risk factor assessment to determine whether heart rate and blood pressure should be monitored.

Adult↗
PubMed2001

Speech and language functioning in paediatric HIV disease.

The Human Immunodeficiency Virus (HIV) can potentially cause impairment to linguistic functioning. This study was the first to compare selected aspects of speech motor control, expressive language and receptive language functioning in individual HIV infected children. Results suggested clinically stable HIV infected children can develop linguistic impairment. Such impairment is in danger of going unnoticed without assessment. Thorough and regular assessment of the linguistic functioning of long-term survivors of paediatric HIV disease is essential if optimal speech and language therapy management strategies are to be devised.

Child, Preschool↗
PubMed2000

The relationship between self-reports and objective measures of disability in patients with late sequelae of poliomyelitis: a validation study.

OBJECTIVE: To establish the validity of 2 objective measures of disability based on 2 self-reports in individuals with the late sequelae of poliomyelitis (LSP). DESIGN: Nonexperimental research design. SETTING: Regional ambulatory clinic specializing in the management of patients with LSP. PARTICIPANTS: Seventeen community dwellers with LSP. INTERVENTION: Completion of 2 exercise tests: the 6-minute walk (6-MW) test and a steady-rate walking test to calculate the cardiorespiratory conditioning index (CRCI), and 2 health status questionnaires: the Sickness Impact Profile (SIP) and Medical Outcomes Study Short-Form 36 (SF-36). MAIN OUTCOME MEASURES: 6-MW distance and the CRCI, and scores from the physical dimensions of the SIP and the SF-36. RESULTS: The 6-MW distance correlated significantly with the physical dimension scores of both the SIP (r = -.57, p < .05) and the SF-36 (r = .67, p < .05). Significant correlations were also observed between the CRCI and the physical dimension scores of the SIP (r = -.51, p < .05) and the SF-36 (r = .70, p < .01). The 2 objective measures correlated significantly with each other (r = .51, p < .05) as did the 2 physical dimension scores of the SIP and the SF-36 (r = -.80, p < .01). CONCLUSIONS: Although objective measures of disability corroborated self-reports of patients with LSP and, thus, supported their validity, each measure has a distinct role in clinical decision making.

Analysis of Variance↗
PubMed2000

Submaximal exercise testing: clinical application and interpretation.

Compared with maximal exercise testing, submaximal exercise testing appears to have greater applicability to physical therapists in their role as clinical exercise specialists. This review contrasts maximal and submaximal exercise testing. Two major categories of submaximal tests (ie, predictive and performance tests) and their relative merits are described. Predictive tests are submaximal tests that are used to predict maximal aerobic capacity. Performance tests involve measuring the responses to standardized physical activities that are typically encountered in everyday life. To maximize the validity and reliability of data obtained from submaximal tests, physical therapists are cautioned to apply the tests selectively based on their indications; to adhere to methods, including the requisite number of practice sessions; and to use measurements such as heart rate, blood pressure, exertion, and pain to evaluate test performance and to safely monitor patients.

Adolescent↗
PubMed1999

Initial clinical experience with a fully automatic in-hospital external cardioverter defibrillator.

Sudden cardiac death due to ventricular tachyarrhythmia remains a significant problem in the in-hospital setting. Although the probability of survival is closely correlated with the rapidity of a response by qualified personnel, response times can be prolonged, even in specialized care units. In an effort to decrease response time, a fully automatic external cardioverter defibrillator was recently devised. This device was evaluated in the in-hospital setting to assess safety and efficacy. A total of 79 patients were studied in a multicenter trial. Patients were monitored with fully functional devices in the electrophysiology laboratory (51 patients) and in the cardiac care unit (28 patients). Performance of the device was assessed by comparing automatic responses to any sustained change in cardiac rhythm, either spontaneous or induced, to a retrospective review of stored ECG data and programmed parameters. During a total duration of 964 hours of monitoring, there were 99 episodes of sustained tachycardia. Therapy was appropriately delivered or advised in all episodes. Therapy was advised in one episode of supraventricular tachycardia. There were no episodes of inappropriate therapy delivery. There were no complications or adverse events. The device performed with a sensitivity of 100% and specificity of 98.8% with an average response time of 22 seconds. In conclusion, this automatic external defibrillator was safe, effective, and functioned as designed. Significant improvement in response time to life-threatening ventricular tachyarrhythmia in the in-hospital setting would be expected if this technology was widely adopted.

Adult↗
PubMed1999

Effects of side lying on lung function in older individuals.

BACKGROUND AND PURPOSE: Body positioning exerts a strong effect on pulmonary function, but its effect on other components of the oxygen transport pathway are less well understood, especially the effects of side-lying positions. This study investigated the interrelationships between side-lying positions and indexes of lung function such as spirometry, alveolar diffusing capacity, and inhomogeneity of ventilation in older individuals. SUBJECTS AND METHODS: Nineteen nonsmoking subjects (mean age=62.8 years, SD=6.8, range=50-74) with no history of cardiac or pulmonary disease were tested over 2 sessions. The test positions were sitting and left side lying in one session and sitting and right side lying in the other session. In each of the positions, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), single-breath pulmonary diffusing capacity (DLCO/VA), and the slope of phase III (DN2%/L) of the single-breath nitrogen washout test to determine inhomogeneity of ventilation were measured. RESULTS: Compared with measurements obtained in the sitting position, FVC and FEV1 were decreased equally in the side-lying positions, but no change was observed in DLCO/VA or DN2%/L. CONCLUSION AND DISCUSSION: Side-lying positions resulted in decreases in FVC and FEV1, which is consistent with the well-documented effects of the supine position. These findings further support the need for prescriptive rather than routine body positioning of patients with risks of cardiopulmonary compromise and the need to use upright positions in which lung volumes and capacities are maximized.

Aged↗
PubMed1999

Cardiopulmonary responses of middle-aged men without cardiopulmonary disease to steady-rate positive and negative work performed on a cycle ergometer.

BACKGROUND AND PURPOSE: Understanding physiological responses to negative work allows therapists to be more knowledgeable when they prescribe this form of exercise. The physiological responses of 12 men without cardiopulmonary disease, aged 39 to 65 years (X=49.7, SD=9.3), to negative work (eccentric muscle contractions) and to positive work (concentric muscle contractions) were compared. SUBJECTS AND METHODS: Subjects performed the 2 types of work on a motorized cycle ergometer at pedaling frequencies of 35, 55, and 75 rpm with a constant power output of 60 W. Steady-rate values of oxygen consumption (VO2), heart rate (HR), minute ventilation (VE), tidal volume (VT), and breathing frequency (fb) were obtained during 6 test conditions (positive and negative work at each of the 3 pedaling frequencies). RESULTS: Values for all measures were greater during positive work than during negative work, except for fb. During positive work, values for all variables were greatest at 75 rpm, except for fb. During negative work, VO2 and HR were greater at 75 and 35 rpm than at 55 rpm, and VE and VT were greater at 75 rpm than at 55 rpm. Breathing frequency was not different among pedaling frequencies. CONCLUSION AND DISCUSSION: The results confirmed that negative work performed on a cycle ergometer is associated with low metabolic cost in older men without cardiopulmonary disease. Although VE was determined primarily by changes in VT during negative work, a comparable disproportionate increase in fb was observed at the start of negative work. Such changes in breathing patterns have implications for the prescription of negative work for patients with lung disease.

Adult↗
PubMed1997

Oxygen transport deficits in systemic disease and implications for physical therapy.

The purposes of this article are to discuss the effects of some common systemic diseases on cardiopulmonary function and oxygen transport and to describe the implications for physical therapists. Pathology of every major organ system can manifest secondary effects on cardiopulmonary function and oxygen transport. Such effects are of considerable clinical significance given that they can be life threatening and that physical therapy usually stresses the oxygen transport system. This article reviews the cardiopulmonary effects of hematologic, neuromuscular, musculoskeletal, gastrointestinal, hepatic, renal, collagen vascular and connective tissue, endocrine, and immunologic conditions. The cardiopulmonary manifestations of some common nutritional disorders (eg, obesity, anorexia nervosa) are also discussed. Physical therapists need to be able to anticipate, detect, and manage the cardiopulmonary manifestations of systemic disease given medical advances and the increasing number of patients with multisystem problems, the aging of the population, the expanding scope of physical therapy practice, and the increased professional and ethical responsibility associated with direct patient access.

Aged↗
PubMed1996

Basal expression and induction of glutamate decarboxylase and GABA in excitatory granule cells of the rat and monkey hippocampal dentate gyrus.

The excitatory, glutamatergic granule cells of the hippocampal dentate gyrus are presumed to play central roles in normal learning and memory, and in the genesis of spontaneous seizure discharges that originate within the temporal lobe. In localizing the two GABA-producing forms of glutamate decarboxylase (GAD65 and GAD67) in the normal hippocampus as a prelude to experimental epilepsy studies, we unexpectedly discovered that, in addition to its presence in hippocampal nonprincipal cells, GAD67-like immunoreactivity (LI) was present in the excitatory axons (the mossy fibers) of normal dentate granule cells of rats, mice, and the monkey Macaca nemestrina. Using improved immunocytochemical methods, we were also able to detect GABA-LI in normal granule cell somata and processes. Conversely, GAD65-LI was undetectable in normal granule cells. Perforant pathway stimulation for 24 hours, which evoked population spikes and epileptiform discharges in both dentate granule cells and hippocampal pyramidal neurons, induced GAD65-, GAD67-, and GABA-LI only in granule cells. Despite prolonged excitation, normally GAD- and GABA-negative dentate hilar neurons and hippocampal pyramidal cells remained immunonegative. Induced granule cell GAD65-, GAD67-, and GABA-LI remained elevated above control immunoreactivity for at least 4 days after the end of stimulation. Pre-embedding immunocytochemical electron microscopy confirmed that GAD67- and GABA-LI were induced selectively within granule cells; granule cell layer glia and endothelial cells were GAD- and GABA-immunonegative. In situ hybridization after stimulation revealed a similarly selective induction of GAD65 and GAD67 mRNA in dentate granule cells. Neurochemical analysis of the microdissected dentate gyrus and area CA1 determined whether changes in GAD- and GABA-LI reflect changes in the concentrations of chemically identified GAD and GABA. Stimulation for 24 hours increased GAD67 and GABA concentrations sixfold in the dentate gyrus, and decreased the concentrations of the GABA precursors glutamate and glutamine. No significant change in GAD65 concentration was detected in the microdissected dentate gyrus despite the induction of GAD65-LI. The concentrations of GAD65, GAD67, GABA, glutamate and glutamine in area CA1 were not significantly different from control concentrations. These results indicate that dentate granule cells normally contain two "fast-acting" amino acid neurotransmitters, one excitatory and one inhibitory, and may therefore produce both excitatory and inhibitory effects. Although the physiological role of granule cell GABA is unknown, the discovery of both basal and activity-dependent GAD and GABA expression in glutamatergic dentate granule cells may have fundamental implications for physiological plasticity presumed to underlie normal learning and memory. Furthermore, the induction of granule cell GAD and GABA by afferent excitation may constitute a mechanism by which epileptic seizures trigger compensatory interictal network inhibition or GABA-mediated neurotrophic effects.

Animals↗
PubMed1996

Apoptosis and necrosis induced in different hippocampal neuron populations by repetitive perforant path stimulation in the rat.

Patients experiencing spontaneous seizures of temporal lobe origin often exhibit a shrunken hippocampus, which results from the loss of dentate granule cells, hilar neurons, and hippocampal pyramidal cells. Although experimental attempts to replicate the human pattern of hippocampal sclerosis in animals indicate that prolonged seizures cause prominent injury to dentate hilar neurons and hippocampal pyramidal cells, dentate granule cells of animals are generally regarded as relatively resistant to seizure-induced injury. By evaluating pathology shortly after hippocampal seizure discharges were induced electrically, we discovered that some granule cells are highly vulnerable to prolonged excitation and that they exhibit acute degenerative features distinct from those of other vulnerable cell populations. Intermittent perforant path stimulation for 24 hours induced acute degeneration of dentate granule cells, dentate hilar neurons, and hippocampal pyramidal cells. However, stimulation for 8 hours, which was insufficient to injure hilar neurons and hippocampal pyramidal cells, was nonetheless sufficient to induce bilateral granule cell degeneration. Degenerating granule cells were consistently more numerous in the infrapyramidal than the suprapyramidal blade, and were consistently more numerous in the rostral than caudal dentate gyrus. Depending on the nature of the insult, acutely degenerating neurons exhibit distinct morphological features that are classifiable as either apoptosis or necrosis, although the degree of possible overlap is unknown. Light and electron microscopic analysis of the acute pathology caused by prolonged afferent stimulation revealed that degenerating hilar neurons and pyramidal cells exhibited the morphological features of necrosis, which is characterized in part by early cytoplasmic vacuolization before nuclear changes occur. However, acutely degenerating granule cells exhibited the clearly distinct morphological features of apoptosis, which include an early coalescence of nuclear chromatin into multiple nuclear bodies, compaction of the cytoplasm, cell shrinkage, and budding-off of 'apoptotic bodies' that are engulfed by glia. Whereas pyramidal cell debris persisted for months, granule cell debris disappeared rapidly. This observation may explain why significant granule cell vulnerability has not been described previously. These data document for the first time that dentate granule cells are among the cell types most vulnerable to seizure-induced injury, and demonstrate that whereas hilar neurons and pyramidal cells undergo a typically necrotic degenerative process, granule cells simultaneously exhibit morphological features that more closely resemble the degenerative process of apoptosis. This finding implies that the type of cell death induced by excessive excitation may be determined postsynaptically by the way in which different target cells 'interpret' an excitatory insult. This experimental model may be useful for identifying the biochemical mechanisms that initiate and mediate neuronal apoptosis and necrosis, and for developing strategies to prevent or induce these presumably distinct forms of neuronal death.

Afferent Pathways↗
PubMed1993

Adrenalectomy-induced granule cell degeneration in the rat hippocampal dentate gyrus: characterization of an in vivo model of controlled neuronal death.

The recent discovery that adrenalectomy results in hippocampal granule cell loss suggested that this phenomenon might be useful as a model of selective, experimentally controlled neuronal death possibly relevant to neurodegenerative disorders. This study was designed to provide a detailed qualitative anatomical description of the phenomenon and to determine whether adrenalectomy-induced dentate granule cell degeneration constitutes a reliable model of selective neuronal death. Silver impregnation staining revealed that granule cell degeneration begins immediately after adrenalectomy and continues for months in both sexes, in young and older adults, and in all strains tested. In one group of 77 adrenalectomized rats, 82% exhibited silver-impregnated granule cells. This phenomenon is extraordinarily selective in that no neurons other than dentate granule cells degenerated after adrenalectomy. There was considerable variability among animals in the number of cells degenerating at a given time-point or in the degree of ultimate cell loss. In the most extreme cases, virtually complete granule cell loss was present throughout approximately 80% of the dentate gyrus. Nissl staining revealed that degenerating granule cells exhibited coalescing of nuclear chromatin into multiple nuclear bodies and pyknosis without accompanying glial swelling. This morphology is distinct from the necrosis caused by other neurotoxic insults and is the subject of the ultrastructural companion paper identifying this type of cell death as apoptosis. Taken together, these results indicate that adrenalectomy reliably initiates an immediate, highly selective, and long-continuing process of hippocampal granule cell degeneration that exhibits morphological features characteristic of apoptosis, rather than necrosis. The possibility that this apoptotic cell death involves a biochemical cascade relevant to programmed cell death and/or neurodegenerative diseases suggests that this model may be valuable for studies of neuronal death and its prevention. Some practical guidelines for use of this model are described.

Adrenalectomy↗
PubMed1993

Electron microscopic analysis of adrenalectomy-induced hippocampal granule cell degeneration in the rat: apoptosis in the adult central nervous system.

As described in the preceding paper, adrenalectomy triggers hippocampal granule cell degeneration that begins within days after adrenalectomy, continues for months, and is the only apparent cell death anywhere within the brain. At the light microscopic level, granule cell degeneration is characterized by coalescing of nuclear chromatin into numerous spherical bodies. Since the morphology at the light microscopic level resembled the nuclear morphology characteristic of "apoptosis" rather than "necrosis," we undertook this ultrastructural study to determine if adrenalectomy induces the morphological features characteristic of apoptosis. Electron microscopy revealed coalescing of nuclear chromatin, compaction of cytoplasm, and the budding-off of cytoplasmic bodies that were engulfed by glia. Mitochondria, the Golgi apparatus, and rough endoplasmic reticulum appeared relatively normal early in the process of granule cell degeneration when nuclear changes were prominent. Presynaptic terminals innervating degenerating granule cells appeared normal. Electron-dense degeneration of granule cell axon terminals in association with normal postsynaptic elements of CA3 pyramidal cells highlighted the extraordinary selectivity of adrenalectomy-induced granule cell death. Ten weeks after adrenalectomy, astrocytes were filled with abnormally abundant glial fibrils and neuronal debris. This "apoptotic" morphology produced by adrenalectomy was clearly distinct from the "necrotic" granule cell morphology produced by intrahippocampal injection of the neurotoxin volkensin. These results indicate that, in a manner possibly analogous to castration-induced prostate cell death, loss of adrenal hormone triggers a process in dentate granule cells that causes the morphological changes characteristic of "apoptosis." Thus, adrenal steroids may be obligatory growth factors for dentate granule cells and their loss may initiate a selective process in the mature brain that is unique or that may normally occur only in the developing brain.

Adrenalectomy↗
PubMed1993

Calbindin-D28k immunoreactivity and selective vulnerability to ischemia in the dentate gyrus of the developing rat.

Hippocampal dentate granule cells normally express the calcium-binding protein calbindin-D28k and, in the adult, are the hippocampal neurons least vulnerable to an ischemic insult. We evaluated hippocampal structure 2-3 days after hypoxic/ischemic insult at postnatal day 7-10, and discovered that, unlike adult granule cells, developing granule cells were irreversibly injured. Localization of calbindin-D28k-like immunoreactivity (LI) revealed that the vulnerable cells were the immature granule cells at the base of the cell layer that were not yet calbindin-immunoreactive. Adjacent granule cells that did not die in response to the hypoxic/ischemic insult were calbindin-immunoreactive. Whether the lack of calbindin-LI in immature granule cells is causally related to their vulnerability, or is a coincidental reflection of cellular immaturity, remains to be determined.

Animals↗
PubMed1993

Movement energetics of individuals with a history of poliomyelitis.

Principles for evaluating the functional capacity of, and, therefore, exercise testing, chronically-disabled populations such as individuals with a history of poliomyelitis are considerably less well established than those for able-bodied persons. Therefore, we examined the use of indexes of movement economy and cardiorespiratory conditioning based on the results of a submaximal exercise test and oxygen consumption studies in individuals with a history of poliomyelitis. Subjects (n = 48) were categorized into four distinct groups, ie, having normal movement economy and either normal (n = 12) or reduced cardiorespiratory conditioning (n = 11), or having reduced movement economy and either normal (n = 10) or reduced cardiorespiratory conditioning (n = 15). There was no relationship between the indexes of movement economy and cardiorespiratory conditioning (p > 0.05) supporting that these indexes reflected physiologically-distinct entities. Irrespective of movement economy, deconditioned subjects had a reduced forced vital capacity (% predicted) (p < 0.05) and a higher resting heart rate (HR) (p < 0.01) compared to conditioned subjects. The difference in resting HR was attributed to conditioning level rather than initial arousal because resting HR and VO2 were comparable on repeated tests (p > 0.05). Although there was no difference in steady-state HR (% predicted maximum) among the four groups (p > 0.05), VO2 (% pred max) was significantly lower for the deconditioned than the conditioned subjects (p < 0.01). We concluded that determining movement economy and cardiorespiratory conditioning with a submaximal exercise test may enhance assessment and treatment outcome evaluation, hence provide a rational basis for rehabilitation interventions in individuals with a history of poliomyelitis.

Adult↗
PubMed1993

Relationships among cane fitting, function, and falls.

BACKGROUND AND PURPOSE: Although canes are among the most commonly used mobility aids, little is known about the relationship between cane prescription and effectiveness. The purpose of this study was to examine the relationships among cane fitting (ie, cane fitter, cane band, and cane length), reported improvements in function, and reduction in falls. SUBJECTS AND METHODS: Cane users living in the community (86 women and 58 men with a median age distribution of 61 to 80 years) and sampled from seven urban shopping centers in British Columbia, Canada, participated in the study. The primary reasons cited for using a cane were joint problems (39%), general balance difficulties (30%), and a combination of joint and balance problems (15%). Measures included appropriateness of cane length and responses to closed-ended questions related to qualifications of the cane fitter, cane band, functional ability with a cane, and falling frequency. RESULTS: Overall, cane use was associated with improved confidence and functional ability. Canes fitted by health care workers approximated the clinically recommended length compared with canes fitted by non-health care workers, which tended to be greater than this length. There was no relationship, however, between cane fitting (cane fitter, cane hand, and appropriateness of cane length) and functional ability with a cane and falling frequency [corrected]. CONCLUSION AND DISCUSSION: We concluded that health care workers may need to reconsider the variables for optimal cane prescription and their specifications for a given individual. The notion of a correct length and cane hand, for example, may be less important than factors such as the indications for cane use, comfort, and enhanced confidence.

Accidental Falls↗
PubMed1992

The effect of postural drainage positioning on ventilation homogeneity in healthy subjects.

Body position is known to have significant effects on oxygen transport. These effects, however, are seldom considered during postural drainage (PD). The purpose of this study was to examine the effect of modified PD positions on ventilation homogeneity (the evenness of the distribution of ventilation), which is a key component of oxygen transport. The single-breath nitrogen washout test was used to obtain an index of ventilation homogeneity (slope of phase 3 [SBN2/L%]). Seventeen healthy individuals, ranging from 22 to 40 years of age ( mean = 28.4, SD = 5.6), performed the single-breath nitrogen test while sitting, lying supine with the bed tipped head down, right side lying, and right side lying with the bed tipped head down. Within-subject one-way analyses of variance and Tukey's post hoc analyses were used to compare differences in SBN2/L% across the four positions. The distribution of ventilation was significantly less homogeneous in the side-lying positions compared with the supine and sitting positions. Although these results reflect a position-induced change in pleural pressure gradient, they also reflect the effect of gravity-independent, intraregional changes on ventilation distribution. Thus, modified PD positioning has a significant effect on ventilation homogeneity, which may predispose a patient to arterial desaturation. Given the complexity of the factors involved, patients considered for PD positioning should be monitored for arterial saturation.

Adult↗