Publications by authors named "Deanna Britton"

18 Publications

  • Page 1 of 1

Dysphagia in Parkinson's disease patients prior to deep brain stimulation: Is screening accurate?

Clin Neurol Neurosurg 2021 Apr 2;203:106587. Epub 2021 Mar 2.

NW Center for Voice & Swallowing, Dept. of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, OR, USA.

Background: Swallowing problems are common in Parkinson's Disease (PD) and aspiration pneumonia is the leading cause of death. Deep brain stimulation (DBS) surgery can successfully manage the motor symptoms of PD when pharmacological management begins to fail. Before DBS it is important to identify baseline dysfunction, but no consensus regarding swallowing screening exists.

Objectives: This study was undertaken to: 1) identify the prevalence of dysphagia prior to DBS; and 2) determine if screening measures or other characteristics were predictive for reduced airway protection.

Methods: A standardized protocol was performed for 137 consecutive patients with idiopathic PD and no confounding medical conditions, including those referred for work-up of dysphagia (n = 57) and those prior to DBS (n = 80). Three validated screening measures were completed before videofluoroscopic evaluation.

Results: On videofluoroscopy, there were significant differences in reduced airway protection by group (dysphagia group: 44 %; pre-DBS group: 21 %). Aspiration also differed by group (dysphagia group: 18 %; pre-DBS group: 8 %) although not significantly. Although there were significant between-group differences, none of the screening measures was predictive of reduced airway protection or aspiration in the sample overall. Male gender, previous videofluoroscopic evaluation, history of pneumonia, and previous DBS surgery were associated with increased aspiration-risk. Age also showed a modest correlation.

Conclusions: Dysphagia is not uncommon prior to DBS. No screening measure accurately predicted reduced airway protection on videofluoroscopy. Abnormal findings on clinical assessment prior to DBS, particularly in patients that are older, male, or have a history of pneumonia, may identify individuals requiring an objective dysphagia evaluation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clineuro.2021.106587DOI Listing
April 2021

Effects of Mouthpiece Noninvasive Ventilation on Speech in Men With Muscular Dystrophy: A Pilot Study.

Am J Speech Lang Pathol 2021 Mar 2:1-9. Epub 2021 Mar 2.

Division of Pulmonary and Critical Care Medicine, University of Washington Medical Center, Seattle.

Purpose The use of noninvasive ventilation (NIV) is on the rise as an alternative to tracheostomy for individuals with neuromuscular disorders with life-prolonging and quality-of-life benefits. This pilot study was designed to determine if mouthpiece NIV (M-NIV) alters speech in individuals with muscular dystrophy (MD). Method Eight men (23-44 years), seven with Duchenne MD and one with Becker MD, who used daytime M-NIV, were asked to sustain phonation, count, and read under three conditions: (a) (no instructions), (b) (cued to use M-NIV with all speaking breaths), and (c) (as tolerated). Breath group and inspiratory durations, syllables/breath group, and relative sound pressure level were determined from audio and video recordings. Results Uncued condition: Participants used the ventilator for all inspirations that preceded sustained phonation and counting. During reading, four participants used M-NIV for all inspirations, one never used it, and three used it for some (19%-41%) inspirations. With- versus Without-M-NIV conditions: Breath group duration was significantly longer across all tasks, syllables per breath group were significantly greater during reading, and inspiratory pause duration during reading was significantly longer with M-NIV than without. Sound pressure level was significantly higher during the first second of sustained phonation with M-NIV (though not for counting and reading). Two participants were unable to complete the reading task audibly without using their M-NIV. Conclusions Speech may be better with M-NIV than without because it is possible to produce longer breath groups and some people with severe respiratory muscle weakness may not be able to speak at all without ventilator-supplied air. Nevertheless, the longer inspiratory pauses that accompany M-NIV may interrupt the flow of speech. Future research is needed to determine the most effective way to use M-NIV for speaking and whether training participants in its use can bring even greater speech benefits.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1044/2020_AJSLP-20-00146DOI Listing
March 2021

Experiences of Speaking With Noninvasive Positive Pressure Ventilation: A Qualitative Investigation.

Am J Speech Lang Pathol 2019 07 15;28(2S):784-792. Epub 2019 Jul 15.

Department of Rehabilitation Medicine, University of Washington, Seattle.

Purpose The aim of this study was to describe experiences of speaking with 2 forms of noninvasive positive pressure ventilation (NPPV)-mouthpiece NPPV (M-NPPV) and nasal bilevel positive airway pressure (BPAP)-in people with neuromuscular disorders who depend on NPPV for survival. Method Twelve participants (ages 22-68 years; 10 men, 2 women) with neuromuscular disorders (9 Duchenne muscular dystrophy, 1 Becker muscular dystrophy, 1 postpolio syndrome, and 1 spinal cord injury) took part in semistructured interviews about their speech. All subjects used M-NPPV during the day, and all but 1 used BPAP at night for their ventilation needs. Interviews were audio-recorded, transcribed, and verified. A qualitative descriptive phenomenological approach was used to code and develop themes. Results Three major themes emerged from the interview data: (a) M-NPPV aids speaking (by increasing loudness, utterance duration, clarity, and speaking endurance), (b) M-NPPV interferes with the flow of speaking (due to the need to pause to take a breath, problems with mouthpiece placement, and difficulty in using speech recognition software), and (c) nasal BPAP interferes with speaking (by causing abnormal nasal resonance, muffled speech, mask discomfort, and difficulty in coordinating speaking with ventilator-delivered inspirations). Conclusion These qualitative data from chronic NPPV users suggest that both M-NPPV and nasal BPAP may interfere with speaking but that speech is usually better and speaking is usually easier with M-NPPV. These findings can be explained primarily by the nature of the 2 ventilator delivery systems and their interfaces.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1044/2019_AJSLP-MSC18-18-0101DOI Listing
July 2019

Swallowing with Noninvasive Positive-Pressure Ventilation (NPPV) in Individuals with Muscular Dystrophy: A Qualitative Analysis.

Dysphagia 2020 02 11;35(1):32-41. Epub 2019 Mar 11.

Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA.

The purpose of the study is to describe experiences of swallowing with two forms of noninvasive positive-pressure ventilation (NPPV): mouthpiece NPPV (M-NPPV) and nasal bilevel positive airway pressure (BPAP) in people with muscular dystrophy. Ten men (ages 22-42 years; M = 29.3; SD = 7.1) with muscular dystrophy (9 with Duchenne's; 1 with Becker's) completed the Eating Assessment Tool (EAT-10; Ann Otol Rhinol Laryngol 117(12):919-924 [33]) and took part in semi-structured interviews. The interviews were audio recorded, transcribed, and verified. Phenomenological qualitative research methods were used to code (Dedoose.com) and develop themes. All participants affirmed dysphagia symptoms via responses on the EAT-10 (M = 11.3; SD = 6.38; Range = 3-22) and reported eating and drinking with M-NPPV and, to a lesser extent, nasal BPAP. Analysis of interview data revealed three primary themes: (1) M-NPPV improves the eating/drinking experience: Most indicated that using M-NPPV reduced swallowing-related dyspnea. (2) NPPV affects breathing-swallowing coordination: Participants described challenges and compensations in coordinating swallowing with ventilator-delivered inspirations, and that the time needed to chew solid foods between ventilator breaths may lead to dyspnea and fatigue. (3) M-NPPV aids cough effectiveness: Participants described improved cough strength following large M-NPPV delivered inspirations (with or without breath stacking). Although breathing-swallowing coordination is challenging with NPPV, participants reported that eating and drinking is more comfortable than when not using it. Overall, eating and drinking with NPPV delivered via a mouthpiece is preferred and is likely safer for swallowing than with nasal BPAP. M-NPPV (but not nasal BPAP) is reported to improve cough effectiveness, an important pulmonary defense in this population.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00455-019-09997-6DOI Listing
February 2020

The Safety and Efficacy of Expiratory Muscle Strength Training for Rehabilitation After Supracricoid Partial Laryngectomy: A Pilot Investigation.

Ann Otol Rhinol Laryngol 2019 Mar 22;128(3):169-176. Epub 2018 Nov 22.

Northwest Center for Voice and Swallowing, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, OR, USA.

Objectives: Expiratory muscle strength training (EMST) is a safe, effective intervention that can be performed at home and may be beneficial for individuals with voice and swallowing disorders. To date there have been few studies of EMST in the head and neck cancer population, and there are no previous reports of its use after supracricoid partial laryngectomy (SCPL). The current prospective clinical pilot study was undertaken to determine the safety and efficacy of a 4-week treatment program.

Methods: Six participants were recruited who had previously undergone SCPL, were medically stable, and had no contraindications for use of the device. At baseline, objective respiratory measurements were collected, dietary status was recorded, and participants were asked to complete a series of validated self-report instruments relating to voice, swallowing, breathing, and cough. Following the completion of treatment, baseline measures were repeated, and participant feedback was solicited.

Results: The majority of individuals found the device easy to use (83%) and beneficial (83%). The side effects of treatment were relatively minor and included dizziness, muscle inflammation, and vocal fatigue. There were improvements in 2 measures from before to after treatment, namely, an average 21% increase in peak cough flow (from 371.67 to 451.33 L/min) and a 38% decrease on the Dyspnea Index (from 6.17 to 3.83). Other measures showed inconsistent changes.

Conclusions: EMST appeared to improve cough strength and reduce dyspnea symptoms after SCPL. Further study of the relative efficacy of EMST compared to other rehabilitation protocols after SCPL is needed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/0003489418812901DOI Listing
March 2019

Swallowing and Secretion Management in Neuromuscular Disease.

Clin Chest Med 2018 06;39(2):449-457

Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University (OHSU), Northwest Clinic for Voice and Swallowing, Physician's Pavilion 250/PV01, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.

Neuromuscular disease frequently leads to dysphagia and difficulty managing secretions. Dysphagia may lead to medical complications, such as malnutrition, dehydration, aspiration pneumonia, and other pulmonary complications, as well as social isolation and reduced overall quality of life. This review provides an overview of dysphagia associated with neuromuscular disease in adults, along with a concise review of swallowing assessment and intervention options.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ccm.2018.01.007DOI Listing
June 2018

Utility of Pulse Oximetry to Detect Aspiration: An Evidence-Based Systematic Review.

Dysphagia 2018 Jun 14;33(3):282-292. Epub 2017 Dec 14.

Northwest Clinic for Voice and Swallowing (NWCVS), Department of Otolaryngology - Head & Neck Surgery, Oregon Health & Sciences University (OHSU), Portland, OR, USA.

Pulse oximetry is a commonly used means to measure peripheral capillary oxyhemoglobin saturation (SpO). Potential use of pulse oximetry to detect aspiration is attractive to clinicians, as it is readily available, quick, and noninvasive. However, research regarding validity has been mixed. This systematic review examining evidence on the use of pulse oximetry to detect a decrease in SpO indicating aspiration during swallowing is undertaken to further inform clinical practice in dysphagia assessment. A multi-engine electronic search was conducted on 8/25/16 and updated on 4/8/17 in accordance with standards published by the Preferred Reporting for Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA). Inclusion criteria included use of pulse oximetry to detect aspiration with simultaneous confirmation of aspiration via a gold standard instrumental study. Keywords included dysphagia or aspiration AND pulse oximetry. Articles meeting criteria were reviewed by two blinded co-investigators. The search yielded 294 articles, from which 19 were judged pertinent and reviewed in full. Ten met the inclusion criteria and all were rated at Level III-2 on the Australian Diagnostic Levels of Evidence. Study findings were mixed with sensitivity ranging from 10 to 87%. Potentially confounding variables were observed in all studies reviewed, and commonly involved defining "desaturation" within a standard measurement error range (~ 2%), mixed populations, mixed viscosities/textures observed during swallowing, and lack of comparison group. The majority of studies failed to demonstrate an association between observed aspiration and oxygen desaturation. Current evidence does not support the use of pulse oximetry to detect aspiration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00455-017-9868-1DOI Listing
June 2018

Speech Versus Speaking: The Experiences of People With Parkinson's Disease and Implications for Intervention.

Am J Speech Lang Pathol 2017 Jun;26(2S):561-568

Portland State University, ORNorthwest Clinic for Voice and Swallowing, Oregon Health & Sciences University, Portland.

Purpose: In this project, we explore the experiences of people who report speech changes associated with Parkinson's disease as they describe taking part in everyday communication situations and report impressions related to speech treatment.

Method: Twenty-four community-dwelling adults with Parkinson's disease took part in face-to-face, semistructured interviews. Qualitative research methods were used to code and develop themes related to the interviews.

Results: Two major themes emerged. The first, called "speaking," included several subthemes: thinking about speaking, weighing value versus effort, feelings associated with speaking, the environmental context of speaking, and the impact of Parkinson's disease on speaking. The second theme involved "treatment experiences" and included subthemes: choosing not to have treatment, the clinician, drills and exercise, and suggestions for change.

Conclusions: From the perspective of participants with Parkinson's disease, speaking is an activity requiring both physical and cognitive effort that takes place in a social context. Although many report positive experiences with speech treatment, some reported dissatisfaction with speech drills and exercises and a lack of focus on the social aspects of communication. Suggestions for improvement include increased focus on the cognitive demands of speaking and on the psychosocial aspects of communication.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1044/2017_AJSLP-16-0087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5576965PMC
June 2017

Incorporating the Principles of Self-Management into Treatment of Dysarthria Associated with Parkinson's Disease.

Semin Speech Lang 2017 07 15;38(3):210-219. Epub 2017 Jun 15.

Department of Speech and Hearing Sciences, Northwest Clinic for Voice and Swallowing, Oregon Health and Sciences University, Portland State University, Portland, Oregon.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0037-1602840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6583887PMC
July 2017

Dysarthria of Spinal Cord Injury and Its Management.

Semin Speech Lang 2017 07 15;38(3):161-172. Epub 2017 Jun 15.

Division of Pulmonary and Critical Care Medicine, University of Washington Medical Center (UWMC), Seattle, Washington.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0037-1602835DOI Listing
July 2017

Beyond Tracheostomy: Noninvasive Ventilation and Potential Positive Implications for Speaking and Swallowing.

Semin Speech Lang 2016 08 27;37(3):173-84. Epub 2016 May 27.

Department of Speech, Language, and Hearing Sciences, University of Arizona, Tucson, Arizona.

For more than a decade, there has been a trend toward increased use of noninvasive positive pressure ventilation (NPPV) via mask or mouthpiece as a means to provide ventilatory support without the need for tracheostomy. All indications are that use of NPPV will continue to increase over the next decade and beyond. In this article, we review NPPV, describe two common forms of NPPV, and discuss the potential benefits and challenges of NPPV for speaking and swallowing based on the available literature, our collective clinical experience, and interviews with NPPV users. We also speculate on how future research may inform clinical practice on how to best maximize speaking and swallowing abilities in NPPV users over the next decade.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0036-1583545DOI Listing
August 2016

Associations between laryngeal and cough dysfunction in motor neuron disease with bulbar involvement.

Dysphagia 2014 Dec 19;29(6):637-46. Epub 2014 Jul 19.

Department of Rehabilitation Medicine, University of Washington, 1959 NE Pacific Street, Box 356490, Seattle, WA, 98195, USA,

True vocal fold (TVF) dysfunction may lead to cough ineffectiveness. In individuals with motor neuron disease (MND), cough impairment in the context of dysphagia increases risk for aspiration and respiratory failure. This study characterizes differences and associations between TVF kinematics and airflow during cough in individuals with bulbar MND. Sequential glottal angles associated with TVF movements during volitional cough were analyzed from laryngeal video endoscopy examinations of adults with bulbar MND (n = 12) and healthy controls (n = 12) and compared with simultaneously collected cough-related airflow measures. Significant group differences were observed with airflow and TVF measures: volume acceleration (p ≤ 0.001) and post-compression abduction TVF angle average velocity (p = 0.002) were lower and expiratory phase rise time (p = 0.001) was higher in the MND group. Reductions in maximum TVF angle during post-compression abduction in the MND group approached significance (p = 0.09). All subjects demonstrated complete TVF and supraglottic closure during the compression phase of cough, except for incomplete supraglottic closure in 2/12 MND participants. A strong positive relationship between post-compression maximum TVF abduction angle and peak expiratory cough flow was observed in the MND group, though it was not statistically significant (r = 0.55; p = 0.098). Reductions in the speed and extent of TVF abduction are seen during the expulsion phase of cough in individuals with MND. This may contribute to cough impairment and morbidity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00455-014-9554-5DOI Listing
December 2014

Endoscopic assessment of vocal fold movements during cough.

Ann Otol Rhinol Laryngol 2012 Jan;121(1):21-7

Department of Rehabilitation Medicine, University of Washington, Seattle, WA 98195, USA.

Objectives: Little is known about the function of the true vocal folds (TVFs) during cough. The objective of this study was to determine the reliability of measuring TVF movements during cough and to obtain preliminary normative data for these measures.

Methods: Sequential glottal angles associated with TVF adduction and abduction across the phases of cough were analyzed from laryngeal videoendoscopy records of 38 young healthy individuals.

Results: The intraobserver and interobserver reliability of 3 experienced measurers was high (intraclass correlation of at least 0.97) for measuring sequential and maximum glottal angles. The TVF abduction velocity during expulsion was significantly higher than the precompression adduction velocity (p = 0.002), but there were no significant differences in maximum angle. No statistically significant differences were seen in maximum TVF angle and velocity when they were compared between the sexes and between the levels of cough strength. True vocal fold closure following expulsion occurred in 42% of soft coughs and in 57% of moderate to hard coughs.

Conclusions: The TVF abduction angles during cough can be reliably measured from laryngeal videoendoscopy in young healthy individuals. The TVF movements are faster for expulsion abduction than for precompression adduction, but the extents of abduction are similar. To validly determine the cough phase duration, simultaneous measures of airflow are needed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/000348941212100105DOI Listing
January 2012

A qualitative study of interference with communicative participation across communication disorders in adults.

Am J Speech Lang Pathol 2011 Nov 3;20(4):269-87. Epub 2011 Aug 3.

University of Washington, Seattle, USA.

Purpose: To explore the similarities and differences in self-reported restrictions in communicative participation across different communication disorders in community-dwelling adults.

Method: Interviews were conducted with 44 adults representing 7 different medical conditions: spasmodic dysphonia, multiple sclerosis, stroke, stuttering, Parkinson's disease, amyotrophic lateral sclerosis, and laryngectomy. This article represents a secondary analysis of qualitative data collected in cognitive interviews during development of the Communicative Participation Item Bank. The data were analyzed to identify themes in participants' experiences related to communicative participation.

Results: Participants described many situations in which they experienced interference in communicative participation. Two themes emerged from the data. The first theme was Interference is both "functional" and "emotional," in which participants defined interference as limitations in accomplishing tasks and emotional consequences. The second theme was "It depends"-sources of interference, in which participants described many variables that contribute to interference in participation. Participants had limited control of some variables such as symptoms and environmental contexts, but personal decisions and priorities also influenced participation.

Conclusions: Despite different impairments and activity limitations, participants described similar communicative participation restrictions. These similarities may have theoretical and clinical implications in terms of how we assess, treat, and study the participation restrictions associated with communication disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1044/1058-0360(2011/10-0084)DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3296484PMC
November 2011

Variables associated with communicative participation in people with multiple sclerosis: a regression analysis.

Am J Speech Lang Pathol 2010 May 30;19(2):143-53. Epub 2009 Nov 30.

University of Washington-Rehabilitation Medicine, Seattle, WA 98195, USA.

Purpose: To explore variables associated with self-reported communicative participation in a sample (n = 498) of community-dwelling adults with multiple sclerosis (MS).

Method: A battery of questionnaires was administered online or on paper per participant preference. Data were analyzed using multiple linear backward stepwise regression. The dependent variable was an item response theory score of communicative participation measured by a subset of items from the Communicative Participation Item Bank asking respondents to rate how much their health condition interfered with participation in real-life speech communication situations. Thirteen independent variables were included in the model as self-reported symptoms: problems thinking, slurred speech, vision loss, pain, mobility, depression, fatigue, perceived social support, age, education level, employment status, gender, and MS duration.

Results: Fatigue, slurred speech, depression, problems thinking, employment status, and social support were significantly associated with communicative participation, accounting for 48.7% of the variance.

Conclusions: Communicative participation is significantly associated with multiple variables, only some of which reflect communication disorders. If the goal of intervention is to improve communicative participation, intervention may need to extend beyond traditional speech-language pathology boundaries to include other health symptoms as well as personal, social, and physical environments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1044/1058-0360(2009/08-0087)DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2873072PMC
May 2010

Baclofen pump intervention for spasticity affecting pulmonary function.

J Spinal Cord Med 2005 ;28(4):343-7

Speech-Language Pathology Clinical Specialist, Harborview Medical Center, 325 Ninth Avenue, Box 359819, Seattle, WA 98104, USA.

Introduction: Muscle spasticity may adversely affect pulmonary function after spinal cord injury (SCI). However, there is limited information regarding the treatment of spasticity as a determinant of pulmonary function. This study presents the case of a man with C4 tetraplegia who had severe spasticity and difficulty weaning from ventilatory support.

Methods: Case presentation.

Results: Severe spasticity likely contributed to respiratory compromise in this patient. Successful and rapid weaning from the ventilator occurred within 3 weeks of baclofen pump placement.

Conclusions: Randomized clinical trials among SCI patients with significant spasticity are needed to determine whether intervention with a baclofen pump facilitates earlier ventilatory weaning.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1864906PMC
http://dx.doi.org/10.1080/10790268.2005.11753832DOI Listing
February 2006

Hemodynamics associated with breathing through an inspiratory impedance threshold device in human volunteers.

Crit Care Med 2004 Sep;32(9 Suppl):S381-6

US Army Institute of Surgical Research, Fort Sam Houston, TX, USA.

Objective: Increased negative intrathoracic pressure during spontaneous inspiration through an impedance threshold device (ITD) causes elevated arterial blood pressure in humans. This study was performed to determine whether the acute increase in blood pressure induced by breathing through an ITD is associated with increased stroke volume and cardiac output.

Design: Randomized, blinded, controlled trial.

Setting: Laboratory.

Subjects: Ten women and ten men.

Interventions: We measured hemodynamic and respiratory responses during two separate ITD conditions: 1) breathing through a face mask with an ITD (impedance of 6 cm H2O [0.59 kPa]) and 2) breathing through the same face mask with a sham ITD (control). Stroke volume was measured by thoracic bioimpedance.

Measurements And Main Results: Compared with the control condition, ITD produced higher stroke volume (124 +/- 3 vs. 137 +/- 3 mL; p = .013), heart rate (63 +/- 3 vs. 68 +/- 3 beats/min; p = .049), cardiac output (7.69 vs. 9.34 L/min; p = .001), and systolic blood pressure (115 +/- 2 to 122 +/- 2 mm Hg [15.33 +/- 0.3 to 16.26 +/- 0.3 kPa]; p = .005) without affecting expired minute ventilation (6.2 +/- 0.4 to 6.5 +/- 0.4 L/min; p = .609).

Conclusions: Breathing with an ITD at relatively low impedance increases systolic blood pressure by increasing stroke volume and cardiac output. The ITD may provide short-term protection against cardiovascular collapse induced by orthostatic stress or hemorrhage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/01.ccm.0000134348.69165.15DOI Listing
September 2004

Effects of inspiratory impedance on the carotid-cardiac baroreflex response in humans.

Clin Auton Res 2004 Aug;14(4):240-8

US Army Institute of Surgical Research, 3400 Rawley E. Chambers Avenue Building 3611, Fort Sam Houston (TX) 78234-6315, USA.

We were interested in a therapeutic device designed to increase carotid-cardiac baroreflex sensitivity (BRS) since high BRS is associated with a lower risk for development of hypotension in humans with experimentally-induced central hypovolemia. We hypothesized that spontaneous breathing through an impedance threshold device (ITD) designed to increase negative intrathoracic pressure during inspiration and elevate arterial blood pressure would acutely increase BRS in humans. We tested this hypothesis by measuring heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressures, and carotid-cardiac BRS in 10 female and 10 male subjects breathing through a face mask at three separate ITD conditions: (a) 6 cm H(2)O; (b) 12 cm H(2)O; and (c) a control (0 cm H(2)O). HR was increased (P = 0. 013) from 64 +/- 3 bpm during control to 68 +/- 3 bpm at 6 cm H(2)O ITD and 71 +/- 4 bpm at 12 cm H(2)O ITD breathing conditions. During ITD breathing, BRS was not altered but responses were shifted to higher arterial pressures. However, SBP and DBP were elevated for both the 6 and 12 cm H(2)O conditions compared to the 0 cm H(2)O condition, but returned to control (sham) levels by 30 minutes after cessation of ITD breathing. There were no gender effects for BRS or any hemodynamic responses to breathing through the ITD. We conclude that breathing with inspiratory impedance at relatively low pressures can increase baseline arterial blood pressure, i. e., reset the operational point for SBP on the baroreflex stimulus-response relationship, in healthy subjects. This resetting of the cardiac baroreflex may represent a mechanism that allows blood pressure to increase without a reflex-mediated reduction in HR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10286-004-0180-4DOI Listing
August 2004