**6. Development of instrumentation for the analysis of the coordination between respiration and swallowing in COPD patients**

This section briefly describes the development of a configurable system that may be used for ambulatory and/or home analysis of swallowing using telemedicine and internet data exchange developed in our laboratory [24]. The general architecture of the instrument is described in Figure 4.

**Reference Subjects Reference test Oral impairment Pharyngeal**

Repetitive Saliva Swallowing Test (RSST) and Modified Water-Swallow Test (MWST)

Laryngeal sensory discrimination test

Electromyography and respiratory inductive plethysmography during noninvasive ventilation

Videofluoroscopy Longer duration

**between respiration and swallowing in COPD patients**

of the tongue base contact with the posterior pharyngeal wall

**Table 1.** Summary of the studies that evaluated the prevalence of dysphagia and other swallowing disorders on

**6. Development of instrumentation for the analysis of the coordination**

This section briefly describes the development of a configurable system that may be used for ambulatory and/or home analysis of swallowing using telemedicine and internet data

(LPSD)

Tsuzuki et al. (2012)

216 Seminars in Dysphagia

Clayton et al. (2012)

Terzi et al. (2014)

Chaves et al. (2014)

patients with COPD.

65 COPD patients

20 COPD patients and 11 healthy subjects

15 COPD patients

20 COPD patients and 20 healthy controls

**impairment**

participants with

swallows in RSST, and dyspnea, coughing or wethoarse dysphonia after swallowing in MWS in patients with

COPD

COPD

Not tested COPD patients have a

worse level of laryngopharyngeal sensory impairment

Longer pharyngeal transit time

Not tested Not tested Not tested Swallowing

Not tested Reduced number of

**Presence of aspiration** **Coordination of breathing and swallowing**

Not tested Not tested

Not tested Not tested

Not observed efficiency and the breathingswallowing pattern improve with NIV compared with spontaneous breathing

Not tested

**Figure 4.** Simplified block diagram of the configurable instrument for the analysis of swallowing disorders.

The instrument allows an unobtrusive monitoring of respiration during feeding using a nasal airflow measurement system based on a nasal cannula attached to a sensitive pressure transducer (176PC; Honeywell Inc., New York, U.S.A.) through a long and flexible connection tube (100 cm length, 4 mm, i.d.). Intranasal air pressure recordings yield minimally intrusive and accurate information about the direction of airflow in real time.

Also included in the basic instrument is a system used to monitor the elevation of the larynx. This movement prevents the entering of the material in the tracheal airway and gives rise to a characteristic vibration pattern that can be used to detect the pharyngeal phase of the swallowing mechanism [47]. This mechanical vibration was measured using an electret microphone (CZN-15E; Ningbo Yuelong Electronics Co., Zhejiang, China) which was placed on the throat at the level of the thyroid cartilage by an apparatus similar to a collar.

The angle of the glass used to drive water was used to non-invasively monitor the beginning of water entering the mouth of the volunteer. To this end, inclinometry data have been obtained from a dual axis accelerometer (ADXL213, Analog Devices Inc., Norwood, MA, U.S.A.). The resulting analogue output value is then used in conjunction with a lookup table to determine the corresponding glass angle relative to the line of gravity.

The module dedicated to telemonitoring applications is battery operated. This subsystem also includes a Palmtop iPAQ HP hx2490 with 520 MHz, 64 Mb of RAM and 192 Mb of ROM, with operational system Microsoft® Windows Mobile® 5.0. For ambulatory applica‐ tion, a data acquisition system was developed using an 18F4550 microcontroller (Micro‐ chip, Arizona, USA).

Regardless of the method used for data acquisition (ambulatory or telemonitoring), the final analysis of the airflow, mechanical vibration and glass angle signals is performed by a dedicated software (Figure 5). It allows the user to automatically calculate the time in the course of the swallowing apnea (s) and the phase in which the swallowing apnea started and stopped in the respiratory cycle (inspiration or expiration).

**Figure 5.** Front panel of the program used to automatically calculate the time in the course of the swallowing apnea (s) and the phase in which the swallowing apnea started and stopped in the respiratory cycle (inspiration or expiration). Figure 5: Front panel of the program used to automatically calculate the time in the course of the swallowing apnea (s) and the phase in which the swallowing apnea started and

Representative examples of the typical morphology of the nasal airflow, mechanical vibration and glass angle signals obtained during a swallowing of 20 mL of water in a normal subject and a dysphagic patient are presented in Figure 6. stopped in the respiratory cycle (inspiration or expiration). Representative examples of the typical morphology of the nasal airflow, mechanical vibration and glass angle signals obtained during a swallowing of 20 mL of water in a

normal subject and a dysphagic patient are presented in Figure 6.

Figure 6: Typical glass angle, larynx mechanical vibration and nasal airflow normal signal morphology during swallowing of 20 mL of water in a normal (A) and a dysphagic patient (B). **Figure 6.** Typical glass angle, larynx mechanical vibration and nasal airflow normal signal morphology during swal‐ lowing of 20 mL of water in a normal (A) and a dysphagic patient (B).

As seen in Figure 6A, the movement necessary to drive water into the mouth of the volunteer is described by the increase in the glass angle. When the angle is near 900 and As seen in Figure 6A, the movement necessary to drive water into the mouth of the volunteer is described by the increase in the glass angle. When the angle is near 900 and water is beginning

to enter the mouth of the volunteer, the swallowing apnea begins. The absence of airflow, which can be observed in the end of the inspiration cycle, demarks the beginning of the deglutition process (near 4.8 s). After the beginning of this event, Figure 6A shows the presence of the mechanical vibration signal indicating the action of protective mechanisms including the movement of the larynx-hyoid complex. Note a small delay between water entering the mouth (glass angle = 900 ) and the movement of the larynx-hyoid complex. After a period of approximately 1.5 s, the apnea reaches its end, and an expiration phase is initiated. Meanwhile, the returning of the glass to the initial position is described by a correspondent gradual reduction of the associated signal to zero.

A representative recording in a patient with dysphagia is shown in Figure 3B. Water entering the mouth of the patient (near 11 s) is accompanied by a first swallowing mark (larynx vibration signal) which lasted approximately 4 s. The corresponding apnea period also lasted approxi‐ mately 4 s. Note that these periods were higher than that presented by the normal volunteer. An important characteristic of this patient is the constant presence of coughing during liquid swallowing. This is related to a clinical history of three cerebral vascular accidents (CVA). This behaviour is in conformity with the hypothesis of an adaptation mechanism in which the patient increases swallowing times to protect itself from aspiration. While similar to the normal subject, the apnea was followed by expiration and a transitory hyperventilation. Figure 3B also shows a second swallowing mark and a second apnea event (≅22s), which was preceded by an expiratory event. This occurs because the patient was not able to swallow all of the 20 mL of water in the first swallowing, therefore, a second swallowing event was necessary. The detailed description presented in Figure 3B confirms the potential of the proposed instrument in the analysis of abnormal swallowing events.
