Cough and Swallow Rehab Following Stroke
Condition: Ischemic Stroke
MeSH terms: Stroke; Ischemic Stroke
Study type: Interventional
Phase: Phase 1/Phase 2

Summary: 
      Stroke is the leading case of neurologic swallow dysfunction, or dysphagia. Post stroke
      dysphagia is associated with approximately 50% increase in the rate of pneumonia diagnoses;
      aspiration pneumonia is the most common respiratory complication in all stroke deaths,
      accounting for a three-fold increase in the 30-day post stroke death rate. The long-term goal
      of this systematic line of research is to decrease the morbidity, mortality, and health care
      costs associated with disordered airway protection following stroke.

      The overall hypothesis central to this proposal is that the ability to protect the airway is
      dependent upon a continuum of multiple behaviors, including swallowing and cough. Safe,
      efficient swallowing prevents material from entering the larynx and lower airway, and
      effective cough ejects aspirate or mucus material. Currently, only one end of the continuum,
      swallowing, is rigorously assessed in stroke patients. However, ineffective or disordered
      cough is indicative of the inability to eject aspirate material or clear mucus and secretions
      from the lower airway. Ineffective clearance and subsequent accumulation of material in the
      lower airway increases the risk of chest infection. Hence, patients at the greatest risk for
      chest infection would not only have disordered swallowing (dysphagia) but also disordered
      cough (dystussia), meaning they are more likely to aspirate material and then cannot
      effectively eject the aspirate from the airway. There is a high likelihood that swallowing
      and cough are simultaneously disordered following stroke. To date, there is a treatment that
      targets both swallowing and cough function in stroke patients.

      Expiratory muscle strength training (EMST) increases expiratory muscle strength (Baker et
      al., 2005) and there is evidence that supports its use to improve both swallow and cough
      functions in patients with Parkinson's disease (Troche et al., in press). This cross-system,
      device-driven approach to rehabilitating multiple contributors to airway protection deficits
      is highly desirable in the stroke population due to the likelihood of the co-occurrence of
      both swallow and cough disorders. To date, EMST has not been tested in stroke patients. We
      propose that by including cough in the screening, evaluation and treatment processes for
      disorders of airway protection, we will be able to better identify and treat patients most at
      risk for airway compromise and associated sequelae.
    

Detailed description: 
      Research Design and Methods This pilot study will include twenty acute (1-14 days post-ictus)
      and subacute (14 days - 6 months post-ictus) ischemic stroke patients between the ages of 50
      and 80 as participants. Once enrolled, participants will complete a battery of pre-training
      baseline measures ('measures' subheading below) and then be randomized to one of two groups:
      the experimental EMST group, or the control group. The training (EMST group) or control
      period will last for 5 weeks, and there will then be a post-training assessment that will
      consist of the same measures that were taken during the initial baseline visit.

      Once informed consent is obtained, medical records will be reviewed for confirmation that the
      patient meets inclusion and exclusion criteria. Cognitive status: Cognitive status in stroke
      brain injured patients is known to impact recovery and relate to dysphagia, risk of
      aspiration, and cough. We will use the National Institutes of Health Stroke Scale (NIHSS)
      assess stroke severity (Appendix 1). The NIHSS will be treated as an independent predictor of
      cough and/or swallow dysfunction.

      Measures

      Maximum Expiratory Pressure: Maximum expiratory (MEP) pressures are an indirect measure of
      expiratory muscle strength. The measurement apparatus consists of a mouthpiece connected to a
      pressure manometer by 50 cm of 2 mm i.d. tubing with a 14-gauge-needle air-leak. In order to
      measure MEP, the participant will be seated with the nose occluded with nose clips. After
      inhaling to total lung capacity, the participant will place his or her lips around the
      mouthpiece and blow out as forcefully as possible. Repeated measures will be taken with a one
      to two minute rest between trials, until three measurements obtained are within 5%. The
      average of these three values will be recorded.

      Lung function test: Forced Vital Capacity (FVC) and Force Expiratory Volume at one second
      (FEV1): The participants will be asked to breathe in to their total lung capacity. The
      participants will then be asked to blow out as forcefully as possible into a computerized
      spirometer. FEV1 is a measure of expiratory volume during the first second of expiration
      during the forced vital capacity maneuver. Alternatively, if the subject is unable to perform
      the cognitive voluntary spirometric task, upper airway respiratory resistance (R5) will be
      measured with impulse oscillometry (IOS, Jaeger Instruments). Impulse oscillometry requires
      the participant to breath through a mouthpiece connected to the computer. The mouthpiece
      apparatus delivers small puffs of air whose reverberations provide measures of upper and
      lower airway resistance. This takes approximately 5-10 minutes to complete.

      Cough: Participants will be instrumented for the measurement of the respiratory airflow
      pattern during spontaneous breathing, voluntary cough and capsaicin induced reflex cough. A
      facemask connected to a pneumotachograph will be used to record the airflow and expiratory
      muscle activity will be measured with surface electromyography (sEMG), with electrodes placed
      over the rectus abdominous muscle, and over the 8th intercostal space. The mouth airflow
      signal and sEMG signal will be digitized and recorded on a desktop computer (Chart,
      ADInstruments, Inc). The computer signals will be analyzed to determine timing and duration
      of the inspiratory, expiratory and compression phases, as well as the peak and mean
      expiratory airflow of each cough (Figure 4), and associated sEMG amplitude measures. Because
      it has been recently reported that acute stroke related brain injury differentially affects
      the motor pattern of voluntary and reflex elicited coughs (Ward et al., 2010), hence it is
      essential to elicit coughs with both peripheral afferent stimulation (capsaicin; 'reflexive'
      cough) and voluntary induced cough.

      Voluntary cough: Participants will be seated with a facemask connected to a pneumotachograph.
      They will be instructed to produce a strong cough three times into the facemask. They will
      rest for one minute between trials. This will take 5 - 10 minutes to complete.

      Reflexive cough / capsaicin administration: After the participant is instrumented with
      facemask, he/she will be seated comfortably in a chair in front of an airflow fume hood. The
      airflow fume hood prevents exposure of the participant and experimenter to the nebulized
      solution except when the participant inhales for the capsaicin challenge. Participants will
      inspire deeply through the nebulizer (containing the capsaicin or a vehicle solution) coupled
      to the facemask and pneumotachograph. The outflow nebulizer gas will be passed through an
      isopropyl alcohol solution to remove capsaicin from the air vented into the fume hood. Dr.
      Davenport holds an FDA IND # 76866 for the use of capsaicin in the study of cough motor
      pattern. This will take 10 minutes to complete.

      Swallowing Evaluation: Videofluoroscopic measures: Swallowing will be assessed using a high
      resolution, dual modality videofluoroscopic (VFS) recording device with signal acquisition
      (digitized at 250 Hz) and digital storage and retrieval of respiratory and swallowing data
      (Digital Swallowing Workstation, model 7100, Lincoln Park, NJ: Kay Elemetrics). The clinical
      swallow examination comprises: a brief swallowing history, an oral motor examination, a 3 oz
      swallowing test, and a Videofluoroscopic Swallowing Examination (VFSE). The oral motor
      examination assesses the strength, timing and tone of jaw, lips, face, larynx and velopharynx
      as these structures all contribute to safe, adequate swallowing. Their impairment is
      predictive of swallowing abnormality. The 3 oz swallow test, requires each person to swallow
      three ounces of water. It is also strongly associated with aspiration on instrumental
      testing. The VFSE includes videotaping the participant in the radiologic suite (Shands
      radiology department) using standard fluoroscopic systems with remote monitor and a standard
      lateral view of the oropharynx. This lateral view will allow visualization of all critical
      oral and pharyngeal structures, including jaw, lips, tongue, soft palate, larynx and pharynx.
      A video counter will imprint a time code on each examination to aid subsequent analysis. Each
      examination will consist of 6, 5-ml and 10-ml thin liquid swallows, 3, 15-ml thin liquid
      swallows, 6, 5-ml and 10-ml swallows of barium pudding, and one, 3oz thin liquid.
      Standardized "bail-out" criteria will be used to eliminate serious aspiration.

      The Modified Barium Swallow Impairment Profile (MBSImp™) will be used to analyze the VFS
      recordings and determine the presence of oral and/or pharyngeal swallowing impairment. The
      MBSImp is a validated tool (B. Martin-Harris et al., 2008) for assessing swallow impairment.
      Six objective components of oral and pharyngeal impairment are included on the scoring form,
      thus giving an overall impression of swallowing performance.

      The penetration-aspiration scale (PAS) (Rosenbek, Robbins, Roecker, Coyle, & Wood, 1996) will
      be used to assess penetration or aspiration; the PAS is an 8-point scale that ranges from 1
      (no penetration/aspiration) to 8 (aspiration with no cough response).

      EMST training procedures As indicated in the Informed Consent Form, after completion of the
      baseline testing, participants will be randomized to either an experimental EMST group, or a
      control group. Participants in both groups will follow any compensatory strategies, including
      diet modifications and/or postural adjustments recommended for safe swallowing based on the
      initial swallowing examination. In addition, the EMST group will receive 5 weeks of EMST.

        1. The EMST group will be given an expiratory pressure threshold trainer, which consists of
           plexiglass tube with a variable tension spring controlling a "pop-off" valve. The
           threshold training device used in this study will be a modification of a commercially
           available device manufactured by HealthScan, Inc. The modification of this device allows
           the pressure threshold to be set up to 160 cmH20. The current device only allows
           pressure threshold settings up to 20 cmH20. The higher pressure-threshold settings are
           necessary to allow the threshold to be set at 75% of the participant's MEP.

        2. The training protocol will consist of five sets of five breaths, five days per week for
           5 weeks with the pressure threshold set at 75% of the participant's most recently
           acquired MEP. The EMST participants will be provided with written (Appendix 2) and
           verbal instructions for the completion of the training protocol. Participants will mark
           the completion of training sets on a log sheet (Appendix 3) each week.

        3. Each EMST participant will be visited at their home by a trained therapist once a week
           during each week of the 5 week training period. The participant's MEP will be measured
           at this time. Three trials will be completed. The maximum value will be used in the
           dataset. Any participant concerns regarding the training program will be addressed at
           this time.

        4. Following the training period, all of the baseline measures described above for
           breathing, coughing, and swallowing will be re-evaluated. This will constitute the
           post-training baseline measures and will occur within one following the 5-week
           intervention

      Control group procedures:

      As indicated in the Informed Consent Form, after completion of the baseline testing,
      participants will be randomized to either an experimental EMST group, or a control group.
      Participants randomized to the control group will not be involved in any EMST treatment
      paradigm or any other exercise treatment paradigm, but as with the EMST group, participants
      may be using compensatory strategies as per standard of care. This will ensure they are able
      to safely maintain adequate nutritional status. Participants in this group will be assessed
      at the pre-training and post-training visits using the identical protocol for that of the
      EMST group. They will not receive weekly home visits.
    

Intervention name(s): Expiratory muscle strength training; Placebo expiratory training; Measures performed on all subjects; Pulmonary function test; Fluoroscopic swallow study
Intervention type(s): Behavioral; Behavioral; Drug; Behavioral; Radiation
Intervention description(s): Small hand held device that provides calibrated (cmH20) resistance to expiratory pressure. Once sufficient pressure is achieved (participant blowing out into the device) a valve is released, letting air flow through.; Device with the same look and feel as the active EMST, but which provides no resistance to airflow.; Capsaicin is a cough-inducing vapor that will be inhaled by participants to induce coughing. The airflow of the cough will be recorded and measures of compression phase duration, peak expiratory flow rate, and post-peak plateau phase will be made.; Measures of forced vital capacity (FVC) and Forced expiratory volume in the 1st second (FEV1), and the ratio between the two measures (FEV1/FVC). Also included is the measure of maximum expiratory pressure. Airflow from the voluntary cough will also be recorded and measured using the spirometric system. These measures will be identical to those made on the capsaicin-induced cough.; Images from the swallow study will be used to determine the modified barium swallow impairment profile (MBSImp) score, as well as the penetration-aspiration score (PA).
Other intervention name(s): EMST; Capsaicin; Spirometry; Modified barium swallow study
Intervention MeSH terms: Capsaicin
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: stroke; dysphagia; dystussia; cough; maximum expiratory pressure