• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 90
  • 68
  • 22
  • 21
  • 11
  • 8
  • 6
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 266
  • 88
  • 85
  • 64
  • 44
  • 41
  • 39
  • 38
  • 38
  • 28
  • 24
  • 24
  • 24
  • 22
  • 21
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Sjuksköterskans förebyggande omvårdnadsåtgärder för att förhindra komplikationer som kan uppstå vid dysfagi : En beskrivande litteraturstudie

Persson, Malin, Scherdin, Sofia January 2012 (has links)
Syftet med studien var att göra en litteraturstudie vilken beskriver hur sjuksköterskans omvårdnadsåtgärder förebygger komplikationer vilka kan uppstå vid måltidssituationer för patienter drabbade av dysfagi till följd av stroke. Studien genomfördes som litteraturstudie med beskrivande design, 12 vetenskapliga artiklar granskades och sammanställdes under tre huvudrubriker; Åtgärder för att förebygga aspirationspneumoni, Nutritionsstöd samt Kvalitetsgranskning av artiklar. Resultatet visade att många av sjuksköterskans omvårdnadsåtgärder kunde minska risken att patienter med dysfagi drabbas av aspirationspneumoni. Det framkom en rad olika kompensationsstrategier och åtgärder sjuksköterskan kunde bidra med, bland annat intensiv munhygien samt stimulering av tunga och mun med is eller annat kallt föremål vilket stimulerar sväljreflexen. Andra åtgärder var rätt sittposition och anpassad konsistens på mat och vätska samt kosttillskott. Resultatet i föreliggande studie visade att utbildning inom förebyggande omvårdnadsåtgärder var nödvändiga för att rätt matningsteknik användes och att kostrekommendationer följdes, samt att det fanns ett lämpligt instrument för sjuksköterskans kompetens vid screening av dysfagi. Vidare påvisade resultatet att emotionellt stöd från sjuksköterskan var viktigt vid måltidssituationer. Slutsatsen var att kunskap om sjuksköterskans omvårdnadsåtgärder vid måltidssituationen leder till färre komplikationer hos patienter med dysfagi. / The aim of this study was to conduct a literature review that describes how nurses care measures can help prevent complications that can occur at mealtime situations for patients suffering from dysphagia following stroke. The study was conducted as a literature review with descriptive design, 12 scientific articles were reviewed and summarized under three main headings: Measures to prevent aspiration pneumonia, Nutrition Support and Quality review of articles.The results demonstrate that many of the nurses care strategies decreased the risk of patients with dysphagia experience aspiration pneumonia. It was found a series of compensation strategies and interventions nurses could contribute, including intensive oral hygiene as well as stimulation of the tongue and mouth with ice or other cold objects which stimulate swallowing reflex. Other measures were correct sitting position and custom texture of food and fluid and dietary supplements. The results of the present study indicated that nurse training was necessary for proper feeding technique and the dietary recommendations were followed, it also demonstrated there was a suitable instrument for nursing skills in screening for dysphagia. Furthermore, the result indicated that emotional support from the nurse was important at mealtime situations. The conclusion was that knowledge about nursing care measures in eating habits resulting in fewer complications in patients with dysphagia.
82

The effects of a volitional breathing technique on swallowing and respiratory coordination in individuals with amyotrophic lateral sclerosis: A pilot investigation

Bohaichuk, Amanda R Unknown Date
No description available.
83

Citric acid inhalation cough challenge: Establishing normative data

Monroe, Margaret Delia January 2010 (has links)
One of the most elusive challenges in the diagnosis and treatment of dysphagia is the reliable identification of silent aspiration (aspiration in the absence of cough). The citric acid inhalation cough challenge offers potential for aiding in identification of silent aspiration; however clinical application of this technique is currently problematic due to an absence of normative data. Therefore, this study aimed to establish a normative data set for the Citric- Acid Inhalation Cough Challenge, as administered with facemask method. 80 healthy subjects will participate in this study, constituting 2 age groups: above and below 60 years, with equal gender representation. On 3 separate trials, they will be asked to passively inhale, via a facemask, nebulised citric acid of concentrations ranging from 08M to 2.6M with placebo interspersed. ‘Natural cough thresholds’ (NCT) and ‘Suppressed Cough Thresholds’ (SCT) will be reached when subjects cough on at least 2 out of 3 trials. The majority (92.5%) of participants reached Natural Cough Threshold by 0.8M, with 68% demonstrating Suppressed Cough Threshold also at this concentration. There were no significant differences found between males and females (p<0.05) for either NCT (p=0.9885) or SCT (p=0.44). Whilst no difference was found between youngers and elders for NCT (p=0.7254), there was a significant difference for SCT (p=0.018), with youngers better able to suppress cough. Over 90% of healthy people were found to elicit cough at 0.8M, inferring that this level would be an adequate guide for use by clinicians testing for presence/absence of cough.
84

sEMG biofeedback as a tool to improve oral motor control and functional swallowing in school age children with cerebral palsy: a case series

Necus, Emma Faye January 2011 (has links)
The number of children with complex medical needs has risen in recent years, due to the increase in medical technology and subsequent increased survival rate of premature infants. This has led to an increasing number of children with complex neurological conditions, such as Cerebral Palsy, being seen by speech-language therapists to address their complex feeding and communication needs in schools (Arvedson 2008). Surface electromyography (sEMG) has been successfully used as a tool to facilitate therapy in adult dysphagia rehabilitation (Huckabee & Cannito 1999), and has been used in studies of dysarthric speech in children with Cerebral Palsy (Marchant, Mc Auliffe & Huckabee 2007). This case series report examines the effect of oral motor control therapy with sEMG biofeedback to increase motor control and inhibit increased muscle tone. Three participants aged 6, 16, and 18 were selected from the population of Kimi Ora Special School. Each of the three participants were offered sixty, twice daily treatment sessions of 30 minutes each focusing on active relaxation, and reducing duration of return to reset after recruitment of the masseter and submental muscles using sEMG biofeedback. After each session each participant was fed a prescribed amount of thin fluid and a range of food textures to encourage generalization of increased control of the submental and masseter muscles during eating and drinking. One participant was withdrawn after 42 sessions, and two participants completed all 60 sessions. Results showed variable improvement in feeding skills, with a notable improvement in anterior food loss. All participants were able to participate fully in the treatment and made significant gains in their ability to control their muscles during treatment sessions which was reflected in the reduction of sEMG amplitudes. This study demonstrated that oral motor control therapy with sEMG is a viable treatment tool, which warrants further larger scale research into its effectiveness.
85

Cough Reflex Testing in Acute Dysphagia Management: Validity, Reliability and Clinical Application

Miles, Anna Clare January 2013 (has links)
Silent aspiration is associated with pneumonia and mortality, and is poorly identified by traditional clinical swallowing evaluation (CSE). Currently, there is no reliable test for detecting silent aspiration during CSE. There is, however, increasing evidence for the validity of cough reflex testing (CRT) for identifying silent aspiration. This test has the potential to significantly improve clinical assessment of dysphagia. The aim of this research programme was to further investigate the validity, reliability and clinical utility of CRT for identifying patients at risk of silently aspirating. Several aspects of CRT were explored during this research programme. Two correlational studies were conducted to validate CRT for identifying silent aspiration against videofluoroscopic swallowing study (VFSS) and flexible endoscopic evaluation of swallowing (FEES). Cough reflex threshold testing was completed on 181 patients using inhaled, nebulised citric acid. Within one hour, 80 patients underwent VFSS and 101 patients underwent FEES. All tests were recorded and analysed by two researchers blind to the result of the alternate test. Significant associations between CRT result and cough response to aspiration on VFSS (p = .003) and FEES (p < .001) were identified. Sensitivity and specificity were optimised at 0.6mol/L in patients undergoing VFSS (71%, 60% respectively) and at 0.4mol/L in patients undergoing FEES (69%, 71% respectively). A concentration of 0.8mol/L had the highest odds ratio (OR) for detecting silent aspiration (8 based on VFSS, 7 based on FEES). Coughing on lower concentrations of citric acid (0.4mol/L compared with 1.2mol/L) was a better predictive measure of silent aspiration. Diminished cough strength has also been associated with aspiration and increased risk of pneumonia. Reflexive cough is our primary defensive mechanism against aspiration and a measure of reflexive cough strength therefore holds greater relevance than one of voluntary cough strength. Despite common use and clinical applicability, the reliability of subjective cough judgements has received little attention. The inter- and intra-rater reliability of subjective judgements of cough in patients following inhalation of citric acid was assessed. Forty-five speech-language therapists (SLTs) were recruited to the first study. Of these, 11 SLTs were currently using CRT in their clinical practice (experienced raters) and 34 SLTs reported no experience with CRT (inexperienced raters). Participants provided a rating of strong, weak or absent to ten video segments of cough responses elicited by inhalation of nebulised citric acid. The same video segments presented in a different sequence were re- evaluated by the same clinicians following a 15-minute break. Inter-rater reliability for experienced raters was calculated with a Fleiss’ generalised kappa of .49; intra-rater reliability was higher with a kappa of .70. Inexperienced raters showed similar reliability with kappa values for inter-rater and intra-rater reliability of .36 and .62, respectively. SLTs demonstrated only fair to moderate reliability in subjectively judging a patient’s cough response to citric acid. Experience in making cough judgements did not improve reliability significantly. In a second study, specific training in cough physiology and cough judgement was provided to 58 trained SLTs. Inter-rater reliability of subjective judgements of cough in patients following inhalation of citric acid was assessed. Participants provided a rating of present or absent, and if present then a rating of strong or weak, to ten video segments of cough responses. Inter-rater reliability for cough presence was calculated with a Fleiss’ generalised kappa of .71 and cough strength was calculated at .61. Years of clinical experience did not improve inter-rater reliability significantly. Experience in using CRT did improve inter-rater reliability. Further validity and reliability research would be beneficial for guiding clinical guidelines and training programmes. By identifying patients at risk of silent aspiration, more informed management decisions can be made that consequently lead to a reduction in preventable secondary complications such as pneumonia. The clinical utility of CRT for reducing pneumonia in acute stroke patients was assessed through a randomised, controlled trial. Three hundred and eleven patients referred for swallowing evaluation were assigned to either 1) a control group receiving standard evaluation or 2) an experimental group receiving standard evaluation with CRT. Participants in the experimental group were administered nebulised citric acid with test results contributing to clinical decisions. Outcomes for both groups were measured by pneumonia rates at three months post stroke and other clinical indices of swallowing management. Analysis of the data identified no significant differences between groups in pneumonia rate (p = .38) or mortality (p = .15). Results of CRT were shown to influence diet recommendations (p < .0001) and referrals for instrumental assessment (p <.0001). Despite differences in clinical management between groups, the end goal of reducing pneumonia in post stroke dysphagia was not achieved. Through this research, the characteristics and outcomes associated with dysphagia secondary to stroke in New Zealand were identified. Baseline characteristics of 311 patients with dysphagia following acute stroke were collected during their hospital stay and outcomes were measured at three months post stroke. Mortality rates were 16% and pneumonia rates 27%. Mean length of stay was 24 days and only 45% of patients were in their own home at three months post stroke. Pneumonia was significantly associated with mortality and increased length of stay. Only 13% of patients received referral for instrumental assessment of swallowing. These data are discussed in reference to the National Acute Stroke Services Audit 2009 and internationally published data. The outcomes for stroke patients with dysphagia in New Zealand are poor with a high risk of pneumonia and long hospital stays when compared internationally. In summary, this research programme has contributed to our understanding of the use of CRT in patients with dysphagia. The addition of a measure of reflexive cough strength may add to clinical assessment but specific training is required to reach adequate reliability. CRT results are significantly associated with aspiration response on instrumental assessment and lower concentrations of citric acid provide a better predictive measure of silent aspiration. CRT can be standardised and therefore is not as susceptible to interpretative variance that plagues much of CSE. Sensitivity and specificity values using this CRT methodology are adequate for CRT to be incorporated into clinical protocols. Inclusion of CRT alone was not shown to be sufficient to change clinical outcomes however integration of CRT into clinical pathways may prove more successful. Further research evaluating the addition of CRT to a comprehensive CSE would add greatly to the field of dysphagia assessment.
86

Incidens av orofaryngeal dysfagi hos nyinsjuknade strokepatienter

Thomasson, Sofia, Wäppling, Sanna January 2014 (has links)
Bakgrund: Dysfagi innebär avvikelser i den normala sväljningsfunktionen och är en vanlig funktionsnedsättning till följd av stroke. Tidigare studier har påvisat att incidensen av dysfagi i det akuta skedet efter stroke är 41-68 %. Kliniskt sett upplevs incidensen ha minskat de senaste tio åren.  Syfte: Syftet med denna studie var därför att (1) undersöka den nuvarande incidensen av orofaryngeal dysfagi hos nyinsjuknade strokepatienter, (2) undersöka hur många av deltagarna som upplever svårigheter att äta och svälja samt bedöms lida av dysfagi enligt vårdpersonal.  Metod: Sextiotre patienter inkluderades i studien, av dessa fick 42,9 % diagnosen stroke. Samtliga deltagare genomgick en dysfagibedömning inom tre dygn efter inskrivning på vårdavdelning. Denna bestod av testerna the Standardized Swallowing Assessment – Svensk översättning (SSA-S) och sväljkapacitetstest (SCT). Deltagare som inte klarade kriterierna i dessa bedömdes lida av orofaryngeal dysfagi.  Resultat: Totalt bedömdes 24 deltagare lida av orofaryngeal dysfagi. I diagnosgruppen stroke var incidensen 48,1 %. Det fanns noteringar om dysfagi i patientjournal hos 20,8 % av deltagarna som enligt testledare bedömdes lida av orofaryngeal dysfagi. Vidare upplevde 29,2 % av samtliga deltagare med orofaryngeal dysfagi samt 30,8 % i diagnosgruppen stroke svårigheter att äta eller svälja.  Slutsatser: Studien indikerar på att incidensen av orofaryngeal dysfagi hos nyinsjuknade strokepatienter inte har minskat i jämförelse med tidigare studier. Däremot tycks det finnas en låg medvetenhet om befintliga ät- och sväljningssvårigheter hos såväl patienter som vårdpersonal. / Background: Dysphagia involves abnormalities in the normal swallowing function, and is a common impairment following stroke. Previous studies have shown that the incidence of dysphagia in the acute phase after stroke is 41-68 %. Clinically interprets that the incidence has declined over the past decade.  Aim: The purpose of this study was to (1) examine the current incidence of oropharyngeal dysphagia in recent-onset stroke patients, (2) investigate how many of the participants who experience difficulty eating and swallowing, and how many is believed to suffer from dysphagia according to healthcare professionals.  Method: Sixty-three patients were enrolled in the study, of whom 42,9 % were diagnosed with stroke. All participants underwent a bedside assessment of swallowing function within three days after enrollment in the nursing ward. The assessment consisted of the Standardized Swallowing Assessment - Swedish translation (SSA-S) and swallowing capacity test (SCT). Participants who did not pass the criteria of these two tests suffered from oropharyngeal dysphagia.  Results: Totally, 24 participants suffered from oropharyngeal dysphagia. The incidence in the stroke group was 48,1 %. There were notes about dysphagia in medical records in 20,8 % of the participants who were judged to suffer from oropharyngeal dysphagia by the test managers. Furthermore 29,2 % of all participants with oropharyngeal dysphagia and 30,8 % in the stroke group experienced difficulty eating or swallowing.  Conclusions: This study indicates that the incidence of oropharyngeal dysphagia in recent-onset stroke patients has not decreased in comparison with previous studies. In contrast, it appears to be a low awareness of existing eating and swallowing difficulties for both patients and healthcare professionals.
87

Videofluorographic observations on swallowing in patients with dysphagia due to neurodegenerative diseases

Nagaya, Masahiro, Kachi, Teruhiko, Yamada, Takako, Sumi, Yasunori 05 1900 (has links)
No description available.
88

BIOELECTRICAL IMPEDANCE ANALYSIS OF MUSCLE FUNCTION AND ACTIVITY: (BIODYNAMIC ANALYSIS)

William Mccullagh Unknown Date (has links)
Abstract There is a need in medicine and research for noninvasive, painless, safe and simple bed-side techniques to measure physiological processes associated with muscle function and activity. Bioelectrical Impedance Analysis (BIA) is a widely used, noninvasive, painless, safe and simple procedure for the measurement of body composition. However, although capable of producing accurate and reproducible data, it is known to be prone to movement artifacts. This poses the interesting question “Could impedance changes be used to monitor movement and, consequently, be related to muscle function or activity?” This project investigated the utility of impedance change as a monitoring technique for physiological processes that involve movement such as muscular contraction, the calf muscle pump, and swallowing. The impedance of leg muscle segments during locomotion, whilst riding a stationary exercise cycle, was measured at discrete frequencies and by bioimpedance spectroscopy to monitor muscle function or activity. Impedance traces were compared to information obtained by electromyography (EMG). Impedance, at a discrete frequency, was able to measure the cadence of cycling and its magnitude was related to the position of the pedal during the pedal cycle. When the cycling action was measured by bioimpedance spectroscopy, R0 and Zc showed a statistically significant difference, (p<0.05), between all angles of the pedal crank cycle while R∞ showed a statistically significant difference between angles in the lower hemisphere of the pedal crank cycle. The cyclical changes in impedance during cycling may be attributed to changes in shape and volume of the muscle during contraction as well as a volume change due to blood and lymph being pumped from the limb by the action of the calf muscle pump. Based on procedures used in the cycling studies, an impedance-based method for the measurement of calf muscle pump function during an exercise protocol, originally designed for use with air plethysmography, was developed. It was shown that impedance measured at 5 kHz provides a simple, non-invasive method for the measurement of the ejection fraction and ejection volume of the calf muscle pump as well as other haemodynamic variables. The impedance-based method was less technically challenging than accepted volumetric methods, such as air plethysmography and strain gauge plethysmography, and non-invasive c.f. ambulatory venous pressure, enabling it to be used repeatedly. Muscle function and activity is not confined to the legs so impedance changes in the arm and forearm during exercise were measured. Impedance measurements, at discrete frequencies and using bioimpedance spectroscopy, of the forearm during contractions of the hand were able to distinguish the difference between a ramp and a pulse contraction. When the impedance of the arm and forearm were plotted against the angle of the forearm to the horizontal during a bicep curl, there was an hysteresis effect. Impedance traces of a bicep curl were compared to an EMG trace of the same action. The larynx is a hollow muscular organ situated in the front of the neck above the trachea consisting of a framework of cartilages bound together by muscles and ligaments. The two major functions of the larynx are deglutition and phonation. Dysphagia, which is becoming more prevalent as the population ages, is defined as difficulty in swallowing thin liquids such as water or juices which splash into the trachea because the patient is unable to control the thin liquid bolus. Aspiration pneumonia and dehydration can be prevented by using thickened liquids which allow patients to achieve a safer swallowing response, but it is difficult to assess this response without interfering with the swallowing process. Impedance pharynography (IPG) is a technique using BIA to monitor an impedance waveform of the swallowing process that presents no radiation hazard to the patient, is non-invasive and does not require specialist trained personnel to operate it. Resistance changes across the neck were measured while subjects swallowed solutions of different viscosities. The resistance changes were distinctive and reproducible for each of the solutions of different viscosities which were swallowed. Measuring the function of the larynx by this method could be useful in the diagnosis and treatment of dysphagia. In conclusion, the studies described in this thesis demonstrate the potential usefulness of the measurement of change in impedance as a measure of muscle activity. Impedance-based methods can measure volume changes associated with changes in cross-sectional area of the muscles involved in contraction as well as compartmental fluid changes caused by the force of the contraction on the surrounding tissues including the vasculature. In particular, measuring the ejection fraction and other haemodynamic variables of the calf muscle pump by impedance has the potential to become the method of choice in the future because it is easy to use, inexpensive, non-invasive, safe, and hygenic. Measuring resistance changes across the neck during swallowing yields distinctive waveforms with features corresponding to the physiological phases of the swallowing process as well as identifying distinctive swallowing patterns associated with the different viscosities of liquids swallowed. Function of the larynx and the associated diseases of the larynx will potentially be easier to diagnose and treat with a safe, non-invasive, inexpensive, portable bed-side method of assessment such as BIA.
89

BIOELECTRICAL IMPEDANCE ANALYSIS OF MUSCLE FUNCTION AND ACTIVITY: (BIODYNAMIC ANALYSIS)

William Mccullagh Unknown Date (has links)
Abstract There is a need in medicine and research for noninvasive, painless, safe and simple bed-side techniques to measure physiological processes associated with muscle function and activity. Bioelectrical Impedance Analysis (BIA) is a widely used, noninvasive, painless, safe and simple procedure for the measurement of body composition. However, although capable of producing accurate and reproducible data, it is known to be prone to movement artifacts. This poses the interesting question “Could impedance changes be used to monitor movement and, consequently, be related to muscle function or activity?” This project investigated the utility of impedance change as a monitoring technique for physiological processes that involve movement such as muscular contraction, the calf muscle pump, and swallowing. The impedance of leg muscle segments during locomotion, whilst riding a stationary exercise cycle, was measured at discrete frequencies and by bioimpedance spectroscopy to monitor muscle function or activity. Impedance traces were compared to information obtained by electromyography (EMG). Impedance, at a discrete frequency, was able to measure the cadence of cycling and its magnitude was related to the position of the pedal during the pedal cycle. When the cycling action was measured by bioimpedance spectroscopy, R0 and Zc showed a statistically significant difference, (p<0.05), between all angles of the pedal crank cycle while R∞ showed a statistically significant difference between angles in the lower hemisphere of the pedal crank cycle. The cyclical changes in impedance during cycling may be attributed to changes in shape and volume of the muscle during contraction as well as a volume change due to blood and lymph being pumped from the limb by the action of the calf muscle pump. Based on procedures used in the cycling studies, an impedance-based method for the measurement of calf muscle pump function during an exercise protocol, originally designed for use with air plethysmography, was developed. It was shown that impedance measured at 5 kHz provides a simple, non-invasive method for the measurement of the ejection fraction and ejection volume of the calf muscle pump as well as other haemodynamic variables. The impedance-based method was less technically challenging than accepted volumetric methods, such as air plethysmography and strain gauge plethysmography, and non-invasive c.f. ambulatory venous pressure, enabling it to be used repeatedly. Muscle function and activity is not confined to the legs so impedance changes in the arm and forearm during exercise were measured. Impedance measurements, at discrete frequencies and using bioimpedance spectroscopy, of the forearm during contractions of the hand were able to distinguish the difference between a ramp and a pulse contraction. When the impedance of the arm and forearm were plotted against the angle of the forearm to the horizontal during a bicep curl, there was an hysteresis effect. Impedance traces of a bicep curl were compared to an EMG trace of the same action. The larynx is a hollow muscular organ situated in the front of the neck above the trachea consisting of a framework of cartilages bound together by muscles and ligaments. The two major functions of the larynx are deglutition and phonation. Dysphagia, which is becoming more prevalent as the population ages, is defined as difficulty in swallowing thin liquids such as water or juices which splash into the trachea because the patient is unable to control the thin liquid bolus. Aspiration pneumonia and dehydration can be prevented by using thickened liquids which allow patients to achieve a safer swallowing response, but it is difficult to assess this response without interfering with the swallowing process. Impedance pharynography (IPG) is a technique using BIA to monitor an impedance waveform of the swallowing process that presents no radiation hazard to the patient, is non-invasive and does not require specialist trained personnel to operate it. Resistance changes across the neck were measured while subjects swallowed solutions of different viscosities. The resistance changes were distinctive and reproducible for each of the solutions of different viscosities which were swallowed. Measuring the function of the larynx by this method could be useful in the diagnosis and treatment of dysphagia. In conclusion, the studies described in this thesis demonstrate the potential usefulness of the measurement of change in impedance as a measure of muscle activity. Impedance-based methods can measure volume changes associated with changes in cross-sectional area of the muscles involved in contraction as well as compartmental fluid changes caused by the force of the contraction on the surrounding tissues including the vasculature. In particular, measuring the ejection fraction and other haemodynamic variables of the calf muscle pump by impedance has the potential to become the method of choice in the future because it is easy to use, inexpensive, non-invasive, safe, and hygenic. Measuring resistance changes across the neck during swallowing yields distinctive waveforms with features corresponding to the physiological phases of the swallowing process as well as identifying distinctive swallowing patterns associated with the different viscosities of liquids swallowed. Function of the larynx and the associated diseases of the larynx will potentially be easier to diagnose and treat with a safe, non-invasive, inexpensive, portable bed-side method of assessment such as BIA.
90

BIOELECTRICAL IMPEDANCE ANALYSIS OF MUSCLE FUNCTION AND ACTIVITY: (BIODYNAMIC ANALYSIS)

William Mccullagh Unknown Date (has links)
Abstract There is a need in medicine and research for noninvasive, painless, safe and simple bed-side techniques to measure physiological processes associated with muscle function and activity. Bioelectrical Impedance Analysis (BIA) is a widely used, noninvasive, painless, safe and simple procedure for the measurement of body composition. However, although capable of producing accurate and reproducible data, it is known to be prone to movement artifacts. This poses the interesting question “Could impedance changes be used to monitor movement and, consequently, be related to muscle function or activity?” This project investigated the utility of impedance change as a monitoring technique for physiological processes that involve movement such as muscular contraction, the calf muscle pump, and swallowing. The impedance of leg muscle segments during locomotion, whilst riding a stationary exercise cycle, was measured at discrete frequencies and by bioimpedance spectroscopy to monitor muscle function or activity. Impedance traces were compared to information obtained by electromyography (EMG). Impedance, at a discrete frequency, was able to measure the cadence of cycling and its magnitude was related to the position of the pedal during the pedal cycle. When the cycling action was measured by bioimpedance spectroscopy, R0 and Zc showed a statistically significant difference, (p<0.05), between all angles of the pedal crank cycle while R∞ showed a statistically significant difference between angles in the lower hemisphere of the pedal crank cycle. The cyclical changes in impedance during cycling may be attributed to changes in shape and volume of the muscle during contraction as well as a volume change due to blood and lymph being pumped from the limb by the action of the calf muscle pump. Based on procedures used in the cycling studies, an impedance-based method for the measurement of calf muscle pump function during an exercise protocol, originally designed for use with air plethysmography, was developed. It was shown that impedance measured at 5 kHz provides a simple, non-invasive method for the measurement of the ejection fraction and ejection volume of the calf muscle pump as well as other haemodynamic variables. The impedance-based method was less technically challenging than accepted volumetric methods, such as air plethysmography and strain gauge plethysmography, and non-invasive c.f. ambulatory venous pressure, enabling it to be used repeatedly. Muscle function and activity is not confined to the legs so impedance changes in the arm and forearm during exercise were measured. Impedance measurements, at discrete frequencies and using bioimpedance spectroscopy, of the forearm during contractions of the hand were able to distinguish the difference between a ramp and a pulse contraction. When the impedance of the arm and forearm were plotted against the angle of the forearm to the horizontal during a bicep curl, there was an hysteresis effect. Impedance traces of a bicep curl were compared to an EMG trace of the same action. The larynx is a hollow muscular organ situated in the front of the neck above the trachea consisting of a framework of cartilages bound together by muscles and ligaments. The two major functions of the larynx are deglutition and phonation. Dysphagia, which is becoming more prevalent as the population ages, is defined as difficulty in swallowing thin liquids such as water or juices which splash into the trachea because the patient is unable to control the thin liquid bolus. Aspiration pneumonia and dehydration can be prevented by using thickened liquids which allow patients to achieve a safer swallowing response, but it is difficult to assess this response without interfering with the swallowing process. Impedance pharynography (IPG) is a technique using BIA to monitor an impedance waveform of the swallowing process that presents no radiation hazard to the patient, is non-invasive and does not require specialist trained personnel to operate it. Resistance changes across the neck were measured while subjects swallowed solutions of different viscosities. The resistance changes were distinctive and reproducible for each of the solutions of different viscosities which were swallowed. Measuring the function of the larynx by this method could be useful in the diagnosis and treatment of dysphagia. In conclusion, the studies described in this thesis demonstrate the potential usefulness of the measurement of change in impedance as a measure of muscle activity. Impedance-based methods can measure volume changes associated with changes in cross-sectional area of the muscles involved in contraction as well as compartmental fluid changes caused by the force of the contraction on the surrounding tissues including the vasculature. In particular, measuring the ejection fraction and other haemodynamic variables of the calf muscle pump by impedance has the potential to become the method of choice in the future because it is easy to use, inexpensive, non-invasive, safe, and hygenic. Measuring resistance changes across the neck during swallowing yields distinctive waveforms with features corresponding to the physiological phases of the swallowing process as well as identifying distinctive swallowing patterns associated with the different viscosities of liquids swallowed. Function of the larynx and the associated diseases of the larynx will potentially be easier to diagnose and treat with a safe, non-invasive, inexpensive, portable bed-side method of assessment such as BIA.

Page generated in 0.0301 seconds