2. Introduction 2 Swallowing involves co-ordinated activity of
muscles of oral cavity, pharynx, larynx and esophagus The whole
process is partly under voluntary control & partly reflexive in
nature Swallowing by definition involves passage of bolus of food
(solid / liquid) from the oral cavity to stomach via the pharynx
and esophagus, passing over the entrance to laryngeal vestibule.
Voluntary control of Swallowing involves control of jaw, tongue,
degree of constriction and length of pharynx and closure of
laryngeal inlet.
3. 3
4. Components of deglutition 4 Deglution has 3 components
Passage of bolus from oral cavity to stomach Protection of airway
Inhibition of air entry into the stomach
5. Deglutition - phases 5 Three stages have been traditionally
described for the sake of convenience. They help in the better
understanding of the physiological process involved. Oral
Pharyngeal Esophageal
6. Oral phase In this phase food is prepared for swallowing
Tongue plays a vital role in this processThis phase is divided into
6 oral preparatory phase and oral phase proper This phase is vital
in all land animals which dont swallow their food as a whole This
phase is under
7. Oral preparatory phase This phase involves breaking down of
food in the oral cavity During this phase the food is chewed and
mixed with saliva making it into a bolus which can be swallowed The
elevators of lower jaw play an important role in bolus preparation
7
8. oral preparatory phase (contd..) 8 Tongue plays a vital role
in bolus formation by the action of its intrinsic muscles which
alters its shape. extrinsic muscles changes its position within the
oral cavity thereby helping in chewing the food by dental occlusion
Occlusal action of the lips help in creating an effective seal
preventing the bolus from dribbling out of the oral cavity. The
action of buccinator muscle helps in pushing the bolus out of the
vestibule into the oral cavity proper
9. oral preparatory phase (contd..) 9 Salivary Glands produce
saliva which contains mucin. Mucin binds the food togather and
helps in bolus formation
10. Bolus formation 10 This is the most important function of
preparatory phase This involves repeated transfer of food from oral
cavity to oropharyngeal surface of tongue Bolus accumulates on the
oropharyngeal surface of tongue due to repeated cycles of upward
& downward movement of the tongue
11. Oral phase proper During this phase the bolus is moved
towards the back of the tongue The contraction of soft palate
prevents nasal regurgitation, also prevents premature movement of
bolus into the oropharynx Once the bolus is of suitable consistency
the transit from mouth to oropharynx just takes a couple of seconds
11
12. Tongue plays a vital role during this phase. Its intrinsic
muscles contracts and reduces its size, while genioglossus muscle
elevates the tongue towards the palate The elevation of the
mandible plays a vital role here When the mandible is elevated the
suprahyoid muscles raises the hyoid bone
13. Pharyngeal phase (Pumping action of tongue &
hypopharyngeal suction) This phase of deglutition is reflexive in
nature during this phase Ventilatory and alimentary streams cross
each other. Dynamic separation of these streams is possible due to
the co-ordination of reflex phase that occurs It just takes a
second for the bolus to traverse the 13 pharynx and reach the
cricopharyngeal area
14. 14 Contraction of diaphragm is inhibited making
simultaneous breathing & swallowing impossible Soft palate is
elevated in order to seal off the nasopharynx (T. palatini & L.
palatini) Vocal cords adduct protecting the airway As the bolus
passes the palatoglossal & palatopharyngeal folds the act of
swallowing becomes reflexive
15. Functions of trigger points in oropharynx Stimulation of
trigger points present in the oropharynx starts off the pharyngeal
reflexive stage of swallowing present at the faucial arches &
mucosa of the posterior pharyngeal wall innervated by
glossopharyngeal nerve 15
16. 16 Stimulation of these trigger points causes dilatation of
pharynx due to relaxation of the constrictors, and elevation of
pharynx & larynx due to contraction of longitudinal muscles The
pharynx constricts behind the bolus thereby propelling it
Contraction of the inferior constrictor moves the bolus towards the
oesophagus
17. Importance of laryngeal elevation during pharyngeal stage
It narrows the laryngeal inlet It ensures better sealing of the
laryngeal inlet by the downturned epiglottis Laryngeal elevation
also contributes to dilatation of pharynx The laryngeal inlet is
closed due to the actions of interarytenoid, aryepiglottic 17 and
thyroepiglottic muscles
18. Role of epiglottis in the pharyngeal phase The movement of
epiglottis occurs in two stages The epiglottis moves from vertical
horizontal position The upper third of epiglottis moves below the
horizontal to a slightly lower level to cover the narrowed
laryngeal inlet 18
19. Esophageal stage This is purely reflexive In this phase
cricopharyngeus relexses and the anterior superior movement of the
laryngohyoid complex acts to open the upper oesophageal sphincter.
The bolus passes through the sphincter and moves along the 19
esophagus by peristalsis.
20. 20 The levator and tensor veli palatini relax lowering the
soft palate. The laryngeal vestibule opens, the hyoid drops and the
vocal cords open This opening of the glottis at the very end of
oropharyngeal swallow sequence is part of the airway protection
mechanism.
21. Neural control of swallowing 21 Two areas of brain are
involved Cerebral cortex Brain stem
22. Neural control (initiation) 22 Initiation of swallow is
voluntary Bilateral prefrontal, frontal and parietal cortices are
involved Swallowing is initiated when food comes into contact with
certain trigger areas like fauces / mucosa of posterior pharyngeal
wall
23. Neural control (initiation) 23 Afferent nerve is the
glossopharyngeal nerve Nucleus tractus solitarius & spinal
nucleus of trigeminal nerve play a vital role Efferents involve
several cranial nerve nuclei which include nucleus ambiguus
(muscles of palate, pharynx and larynx), hypoglossal nucleus
supplying the muscles of the tongue, motor nuclei of trigeminal and
facial nerves supplying the muscles of face, jaws and lips.
24. Role of medulla 24 There are two groups of neurons in the
medulla while lie between the afferent and efferent system First
group lie in the dorsal medulla above the nucleus of the solitary
tract The second group lie in the ventral medulla around nucleus
ambiguus These groups of neurons are named as lateral & medial
medullary swallowing centers
25. Role of central pattern generator 25 Central pattern
generator are a set of neurons capable of initiating sequential
swallow These neurons act like a cardiac pacemaker Since the
process of swallowing and breathing are interlinked there is a
certain degree of central co ordination taking place
26. Phase of respiration & swallowing 26 Swallowing occurs
during expiratory phase of respiration This helps in clearing food
material left in the vestibule. Thus it should be considered to be
a protective phenomenon The rhythm of respiration is reset after a
successful swallow
27. 27 Functional investigations of the upper gastrointestinal
tract
28. Common principles 28 A detailed history of onset and
progression, specific symptoms and relief strategies. Awareness of
adverse situations during assessment. Recording clinical
observations, instructions, bolus volumes and consistencies given.
Accurate recording of penetration (material entering the larynx but
remaining above the vocal folds) or aspiration (below the level of
the vocal folds). Assessing patients in their usual feeding
position. Awareness of multifactoral risks for developing
pneumonia.
29. 29 Challenging the swallow during assessment by increasing
the speed and bolus volume if necessary up to the safe limit. Both
single mouthful and continuous swallowing should be recorded.
Sterilizing equipment from contamination of nasal mucus and blood,
due to the semi-invasive nature of nasendoscopy and manometry. A
team approach, including speech and language therapists,
radiologists, otolaryngologists, gastroenterologists, neurologists
and psychiatrists, etc., as required.
31. RADIOLOGY 31 There are two distinctly different barium
swallows available the traditional barium swallow, video
fluoroscopy (aka modified barium swallow or dynamic swallowing
study).
32. Barium swallow 32 Includes both static and dynamic
components to identify intrinsic disease (tumours, diverticula,
webs and dysmotility) and extrinsic disease (cervical osteophytes,
enlarged thyroid gland). The oesophageal lumen is distended with
liquid barium, or coated in thick barium and distended by gas to
show intrinsic irregularities and extrinsic impressions. Static
imaging with plain radiographs provides information on structural
abnormalities (e.g. Zenker's diverticulum, cervical osteophytes),
but little contribute to the investigation of dysphagia.
33. 33 Both the oral and pharyngeal stages should be assessed
even if the complaint is only oesophageal as 35 percent of patients
have simultaneous disorders of the pharynx and oesophagus and the
level of the lesion does not necessarily correspond to the site of
the patient's symptoms.
34. Videofluoroscopy 34 Video fluoroscopy is a dynamic
fluoroscopic imaging procedure Advantageous for observing all
stages of swallowing, estimating the amount of aspiration, and
identifying structural or anatomical abnormalities as well as the
physiological abnormalities causing dysphagia.
35. PROCEDURE 35 Patients are assessed in a sitting position
Boluses are given in increasing volume to minimize the risk of
aspiration of large amounts of barium, often starting with 1 mL to
coat oral structures. All consistencies are given (liquid,
semi-solid and solid) using video fluoroscopic specific contrast
material. These are designed to optimize bolus visualization using
standard viscosities and to minimize adherence and coating on
mucosa.
36. 36 Simultaneous viewing of the oral, pharyngeal and
laryngeal areas should be included. Images are recorded on
videotape or digitally, in the lateral and anterior-posterior views
for later analysis and interpretation. If dynamic measurements of
distance and area are to be calculated, then a metal ring of known
diameter (e.g. coin) is taped in the midline to the underside of
the chin for calibration.
37. ANALYSIS 37 Subjective interpretation of video fluoroscopy
by experienced clinicians provides descriptions about the bolus
flow, reactions to a misdirected bolus and variations from the
normal anatomy and physiology. Rating scales attempt to standardize
observations over time or between clinicians, for parameters of
oral transit, pharyngeal transit and laryngeal valving and for
penetration and aspiration.
38. 38 Objective analyses of videofluoroscopy are called
dynamic swallow study measurements or kinematics of swallowing.
These involve capturing and manipulating digital images with
computer technology to make exact timing measures of bolus flow and
movement of structures, as well as spatial measurements of distance
and area against reference points.
39. Fluroscopic imaging of swallowing 39
40. 40
41. 41
42. 42
43. 43
44. 44
45. 45
46. 46
47. Video-abc VF 47
48. vf 48
49. ADVANTAGES 49 All stages of the swallowing mechanism are
seen. Estimates of volume, depth and clearance of aspiration can be
made. A full range of consistencies can be tested. Anatomical
abnormalities can be detected (pouches, diverticulae, fistulae).
Biofeedback to patients
50. LIMITATIONS 50 Radiation exposure to the patient,
especially for repeated or lengthy studies.. High cost of equipment
and involvement of several staff. Patient intolerance of procedure.
Difficulties with seating some patients within the confined
space.
51. 51 Properties of barium are designed to coat structures, so
liquid and food containing barium does not behave in the same way
as normal liquids or food. Limited information is gained about
mucosa and secretions, sensation, inter-bolus pressure, and details
of glottic closure. Greater standardization of the procedure, with
higher interjudge reliability between experienced clinicians,is
required before it is truly a 'gold standard' technique.
52. CONTRAINDICATIONS 52 Patients without a pharyngeal swallow,
as aspiration of barium will almost certainly occur. Unsuitable
patients (e.g. those who are unable to maintain a stable position,
drowsy, uncooperative, nil by mouth for reasons other than
dysphagia, have adverse reactions to contrast media, should avoid
unnecessary exposure to radiation). Caution needs to be taken when
patients are suspected of large volume aspiration, or have a
history of respiratory distress/arrest due to aspiration.
53. 53 If large volume aspiration is suspected, there should be
a small volume 5 mL) initial test swallow using water soluble
contrast materials such as nonionic isotonic agents (e.g. Omnipaque
or Gastromiro). Aspiration of barium can be assessed with a chest
radiograph to document the pattern and extent of aspiration, before
suction and physiotherapy. Repeated or prolonged radiation
exposure.
54. 54 Oesophageal motility is assessed with multiple single
swallows in different positions, including recumbent (unlike in a
videofluoroscopy assessment of oropharyngeal dysphagia) , to assess
peristalsis without the effect of gravity. Continuous and single
swallows are observed separately as a second swallow obliterates
peristalsis of the first. The oesophageal stage lasts for 8-20
seconds.
55. CT & MRI 55 These techniques each show structural
lesions, for example the intracranial disease causing neurogenic
dysphagia ? More recently, high speed MRI has been used for dynamic
analysis of the pharyngeal phase of swallowing, where the oral,
pharyngeal and laryngeal musculature can be evaluated during
movement. experimental and costly, and patients need to be supine -
which does not reflect the true physiology of swallowing.
56. Fibreoptic endoscopic evaluation of swallowing (FEES) 56
Also known as video endoscopic evaluation of swallowing (VEES). Or
'milk nasendoscopy. Trans-nasal insertion of the nasendoscope
provides assessment of pharyngeal and laryngeal anatomy and
physiology at rest and in the pre-and post -swallow stages of dry
(saliva) and bolus swallows, using normal food and drink.
57. Fibreoptic endoscopic Evaluation of swallowing with sensory
testing (FEESST) 57 This is extended technique Quantitatively
measures sensory loss in the supraglottic larynx and pharynx by
sending air pulses of differing intensity, duration and frequency
through an additional port in the endoscope. it is an important
development as reduced or absent laryngeal sensation found in
endoscopy correlates with silent aspiration and thus the risk of
aspiration pneumonia.
58. PROCEDURE 58 The patient sits upright, the nostrils are
examined to detect any septal deviation. topical anaesthesia is
applied to the nasal passages (sparingly to avoid desensitizing the
pharynx and larynx). Dry and bolus swallows of coloured liquid and
food (using food colouring), are given in measured volumes.
59. Four different views allow observation of anatomy and
physiology during swallowing as follows: 59 1. Nasal passage for
elevation of the dorsal side of the velum. 2. Nasopharynx for nasal
reflux and lateral and posterior pharyngeal walls. 3. Oropharynx
for base of tongue, epiglottis and Larynx. 4. Hypopharynx for
pyriform fossae, vocal folds and upper
60. Equipment 60 Includes a flexible nasendoscope, with camera
for video or digital (including auditory) recording and slow motion
playback facilities, with an additional colour monitor for
immediate biofeedback with the patient. Developments include
reducing the scope diameter, picture clarity and size, light source
strength and portability. For FEESST, a specially designed scope
and pulse generator are needed to deliver quantifiable air Pulses
.
61. ADVANTAGES 61 Good views of any alterations in the anatomy
and of muscular function in the nasopharynx, oropharynx and
hypopharynx. Quantitative objective assessment of pharyngeal and
laryngeal sensitivity with FEESST. Assessment of initiation and
maintenance of airway protection. Visualization of secretions and
any pooling of secretions, thus helping overall management.
62. 62 Ability to assess swallow without giving food or drink
to those patients who are nil by mouth. Observation of swallowing
with a range of normal food and drink. Lengthy or repeated
assessments without radiation exposure. This enables assessment
throughout a meal (to evaluate swallow fatigue, effective of
cumulative bolus residue, delayed reaction to aspiration and
effectiveness of coughing). Real time and repeated biofeedback to
the patient for evaluating the effectiveness of therapeutic
manoeuvres. Portable and easy implementation at the bedside and in
the clinic.
63. LIMITATIONS No view for evaluation of bolus management in
the oral cavity. Loss of view ('whiteout') during the swallow due
to pharyngeal constriction around the endoscope lens. Quantitative
measures of structure displacement are not possible. Limited
ability to estimate amount of aspirated material. 63
64. CONTRAINDICATIONS 64 Unsuitable patients (e.g. those who
are unable to maintain a stable position, drowsy, uncooperative) .
Predisposition to risk factors (history of bronchospasm or
laryngospasm, severe heart disease, recent respiratory distress,
allergies) . Lack of appropriate medical and nursing support.
Physical obstruction to passing the scope (e.g. extreme deviation
of septum, oedematous mucosa, hypersensitivity) . Obscured view
(e.g. large epiglottis, thick secretions) Maxillary and other
supraglottic resections.
65. Risks 65 The potential complications listed below are
extremely rare, however, awareness of the risks is important for
those performing FEES. Aspiration (suction equipment should be
readily available). Vasovagal responses of hypotension, bradycardia
or cardiac dysrhythmia. These risks are minimized by local
anaesthesia of the nasal mucosa and care manipulating the scope in
the hypopharynx.
66. 66 Laryngospasm is less likely to occur in patients with
pooling and aspiration of secretions who also have poor tactile
sensitivity of the larynx, and who therefore usually need sensation
testing. Probing of the hypopharynx and larynx should be cautious
in those who swallow normally, are asymptomatic of aspiration, with
an adequate cough reflex. Nose bleeds can be avoided by the use of
topical decongestant and lubrication of the scope. Adverse
reactions to the topical anaesthetic are rare, but take an adequate
case history, adhere to recommended doses and have resuscitation
measures available.
67. Video- FEES 67
68. MANOMETRY 68 Directly measures:- amplitude and duration of
contraction and relaxation pressures in the pharynx, UOS,
oesophagus and lower oesophageal sphincter (LOS). Measurements are
taken at rest and during swallowing.
69. Oesophageal Manometry 69 The oesophageal peristaltic wave
pressure rises slowly to approximately 50 mmHg, and falls rapidly.
Secondary peristaltic waves arise locally in response to
distension, needed for more solid bolus transportation. Tertiary
oesophageal contractions are irregular, nonpropulsive contractions
involving long segments of the oesophagus. The 3 cm long LOS
behaves like the UOS, but with a lower tonic (resting) contraction
pressure of 10-30 mmHg relative to intragastric pressure. It
remains closed except for relaxation when the bolus and peristaltic
wave arrive, as swallowing induces inhibition of lower oesophageal
sphincter tone activity.
70. Pharyngeal Manometry Pressure changes in the oropharynx and
UOS are required for effective bolus transit and UOS opening during
swallowing. UOS opening involves: Cricopharyngeal muscle
relaxation, preceding opening by 0.1 second; Hyoid and laryngeal
elevation, pulling the UOS open; Pharyngeal and tongue base
pressure (up to 90 mmHg) on the bolus further pushing open the UOS;
Cricopharyngeal elasticity allowing the UOS to stretch open for
larger boluses; 70
71. 71 Closure of the UOS with increased pressure (90 mmHg) ;
Return to an UOS tonic (resting) pressure of approximately 45 mmHg.
The UOS remains closed with increased tonic pressure with each
inspiration to avoid aerophagy.
72. LIMITATIONS 72 Conventional pharyngeal manometry involves
using a catheter with a limited number (three or four) of pressure
sensors spanning the oropharynx and hypopharynx (including the
UOS), in a unidirectional or multidirectional orientation.
Susceptible to technical difficulties with accurate sensor
placement, and inter- and intra subject variation. Radial asymmetry
of the UOS, as anterior-posterior pressures are two or three times
greater than those recorded laterally because contraction of the
cricopharyngeus muscle compresses the UOS against the trachea into
an oval slit-like aperture. Longitudinal (axial) asymmetry of the
UOS, with larger anterior pressures closer to the pharynx and
larger posterior pressures closer to the oesophagus, especially in
men;
73. Upward movement of the UOS during swallowing due to
laryngeal movement. Consequently the sensor may be left in the open
oesophageal lumen without recording UOS relaxation. Sensitivity of
UOS to diameter size requires the smallest diameter catheter
possible (e.g. 3 mm or less) to avoid inaccurate and increased UOS
tonic pressure readings; UOS tonic pressure increases with stress
and decreases during sleep; Over 60 years of age, tonic pressures
decline and pharyngeal pressures during swallowing increase as a
result of reduced compliance of the UOS, thus requiring greater
force to push large boluses through a less stretchable sphincter
73
74. 74 The barrier formed by LOS tonic pressure is lower after
meals and tighter at night. Similar to the UOS, measurement of the
LOS tonic pressure is complicated by radial asymmetry and a
respiratory pressure fluctuation. Because of the differences in
anatomy and physiology and the frequency of recordings, catheters
with miniature strain gauge pressure transducer sensors are
required.
75. High-resolution manometry 75 Recent advance over
conventional manometry for taking measurements of the oesophagus
and upper and lower oesophageal sphincters. It has been made
possible by the development of micro-manometric water-perfused
assemblies and miniaturized solid-state pressure sensors. The
presence of closely spaced recording sensors in HRM (up to one
pressure sensor per cm) provides several procedural advantages over
conventional manometry.
76. 76 It removes the need for the time-consuming station pull
through procedure and facilitates the accurate positioning of the
catheter. For pharyngeal and UOS measurements, a solid state
high-resolution manometry catheter can have a total of 36 pressure
sensing elements. Sensors are spaced at 1 cm intervals; with each
sensor detecting pressure changes over a length of 2.5 mm and
consisting of 12 circumferentially dispersed smaller sensing
elements. The pressure recorded at each axial location is the mean
pressure measured from the 12 elements.
77. 77 Computer technology allows the large data set acquired
by HRM to be analysed and presented in realtime. Concurrent video
fluoroscopy images displayed in the same record as HRM allow
simultaneous analysis, HRM detects segmental abnormalities of
oesophageal function and predicts the success of bolus transport
more accurately than conventional oesophageal manometry, and
identifies clinically important abnormalities not detected by other
investigations
78. High-resolution manometry video 78
79. 79
80. Manofluoroscopy 80 Pharyngeal manometry is rarely the first
or sole study used to evaluate swallowing function, because of the
limitations , particularly when using conventional manometry. More
information is provided when it is performed simultaneously with
videofluoroscopy, termed manofluoroscopy or videomanometry. Shows a
simultaneous image with pressure readings so that clinicians gain
information about bolus flow relative to anatomical movements.
Radio-opaque metal housing around each pressure sensor gives
accurate information about the placement and position of the
sensors during movement to ensure.
81. Advantages 81 Manofluoroscopy aids clinical decisions about
the need for medical procedures: It provides information to
distinguish between UOS opening with and without relaxation of the
cricopharyngeal musculature. Where adequate UOS relaxation is
occurring, manofluoroscopy can help to differentiate between poor
opening of the UOS secondary to weak pharyngeal and tongue forces;
poor elevation of the hyoid; and decreased elasticity of the
cricopharyngeus muscle. Videofluoroscopy alone without manometry
cannot make the above distinctions.
82. Procedure 82 Standard methodology for oropharyngeal
manometry is needed because of the technical and subject variables.
To date, Normal and dysphagic results are not directly or
numerically comparable because of different equipment and
procedures. Salassa et al. have proposed catheter standards for
pharyngeal manofluoroscopy, which aim to enable comparison of the
same patient over time; to establish normal ranges for all
parameters; and to evaluate abnormal results in relation to the
diagnosis, treatment, outcome and effectiveness of treatments.
83. Equipment 83 Sensor type Catheters with miniature strain
gauge pressure transducer sensors are required for pharyngeal and
UOS measurements for the following reasons. Striated muscle
contractions are quicker in the oropharyngeal area, producing
altering pressures of higher frequency and amplitude, compared with
the slower smooth muscle contractions in the oesophagus. The
pharyngeal pressure 'wave' travels at a speed of 9-25 cm per second
(requiring a recording frequency of over 50 Hz), whereas the slower
oesophageal wave travels at 4 cm per second (requiring a recording
frequency of 5 Hz).
84. Patients can be tested in a normal upright position, unlike
the supine position with water perfused catheters. Although less
expensive, water perfused catheters are usually slower to set up
and use, and they also introduce water into the pharynx, so causing
unwanted swallows and poor tolerance. 84
85. 85 Catheter The diameter should be small (3 mm or less)
both for comfort and to avoid the reactive increase in UOS tonic
pressure. Catheters with fibreoptical 'sensors' are available, and
these provide circumferential readings without increasing the
catheter diameter. An ovoid shaped catheter helps to maintain
correct orientation, (as UOS radial pressures are asymmetrical).
Clear markings in centimetres, with the distal sensor marked at 0
cm, indicates anterior and posterior orientation, and helps with
the inter-subject variation in pharyngeal length and UOS high
pressure zone length.
86. 86 Catheters need to be 100 cm long for oseophageal
manometry. A short (4 cm) malleable section of the catheter should
extend past the most distal sensor to enable easier naso-pharyngeal
insertion Also to allow some of the catheter to pass into the
oesophagus to provide catheter stability laterally and horizontally
during manometry recordings
87. 87 Sensor spacing and placement in conventional manometry
One sensor each should be placed in three (or four) locations,
which are level with the tongue base, hypopharynx, UOS (and upper
cervical oesophagus); (with 2 and 3 cm between the sensors in the
order stated above) Unidirectional in-line sensors, orientated
posteriorly, capture readings of maximum amplitude. The advantage
of circumferential sensors is that radial asymmetries can be
averaged, and readings are not affected by unwanted changes in the
orientation of the catheter.
88. Correct placement of the UOS sensor can be seen during
swallowing by production of a waveform that has a negative nadir,
preceded and followed by an elevated pressure wave and clearing
wave. A pressure transducer too high in the nasopharynx should be
avoided in case the readings record the soft palate against the
posterior pharyngeal wall. 88
89. 89 The techniques of station pull through (SPT) or rapid
pull through (RPT) are used to position the catheters accurately.
Each sensor passes the DOS in Turn. In HRM, the above procedural
difficulties are overcome by the large number of circumferentially
placed and closely spaced sensors.
90. METHODOLOGY 90 Salassa et al. also suggest that methodology
guidelines are still needed in order to standardize: Bolus volumes,
consistencies and temperatures; Duration of swallow intervals;
Single or multiple swallow analysis; Methods to obtain and values
of pressure recordings to analyse; Comparable software analysis
systems.
91. Recordings 91 A computerized mulitchannel recording device
is used to collect store and display the pressure readings. A
channel is needed for each transducer pressure reading, and these
are displayed in graph form with amplitude (x axis) against time (Y
axis).
92. 92 Computer recordings are accurate, quick and unbiased.
Automatic data collation into a database gives faster analysis and
interpretation. The frequency by which pressure reading data is
recorded needs to be standardized. Each laboratory needs to decide
whether to average all the readings taken at the UOS) and for this
to be a constant in recorded values over time and between
patients.
93. Calibration 93 Regular calibration of the equipment is
necessary before the equipment is used. The measurement of UOS
pressure is usually expressed relative to intrapharyngeal zero
baseline, (equivalent to atmospheric pressure). Sensors are zeroed
to an accurate baseline of atmospheric pressure) then a known
pressure (e.g. 200 mmHg) is applied to calibrate) before readings
are taken.
94. 94 CONTRAINDICATIONS Patients suspected of having a
perforated gastrointestinal tract. Same as Endoscopy.
95. Analysis 95 UOS tonic (resting) pressures, and variations
in pressure in the pharynx, UOS and oesophagus during swallowing
are the main measurements. Large numbers of swallows per subject
are needed due to intra-subject variability. Two types of pressure
can be analysed, and both are seen within one pressure wave shape :
1. Bolus pressure on the sensors as they are surrounded by fluid,
also called intra-bolus or luminal or cavity pressure, and usually
small in amplitude. 2. Contact pressure from contraction of the
lumen walls on the sensors during
96. 96 Measurements made include: 1. maximum and minimum
pressures; 2. duration of contraction with the sequence, and
relative timing of contractions and relaxations.
97. OTHER INVESTIGATIONS 97 Respiration The oropharyngeal tract
is the same anatomical channel for swallowing and breathing,
resulting in the need for deglutition apnoea and the potential risk
of aspiration. Respiratory recordings can measure the duration and
timing of deglutition apnoea, direction and rate of airflow and
thus a more complete picture of the physiology of swallowing.
Continuous recordings of oxygen saturation by pulse oximetry have
also been investigated as a possible marker of aspiration with
conflicting results.
98. Ultrasound 98 The ultrasound transducer with high frequency
sounds ( > 2 MHz) is placed sub mentally to produce dynamic
images of the soft tissue in the oral cavity and parts of the
oropharynx, and the motion of the hyoid can be tracked. It is
noninvasive and risk free. Quality of the tongue image, for
measuring tongue movements, is not easy to interpret. The
pharyngeal stage of swallowing cannot be viewed.
99. Oesophageal pH monitoring 99 Prolonged (24-hour ambulatory)
pH monitoring is the most reliable method of diagnosing
gastro-oesophageal reflux, especially atypical presentations. The
distal oesophageal pH probe is placed 5 cm above the LOS (position
determined by manometry) and the proximal one below the UOS, thus
any reflux is measured along the entire length of the oesophagus.
However, the invasive technique prevents some patients from
undertaking activities that provoke reflux during the
investigation, so underestimating their problems?
100. Scintigraphy 100 This procedure tracks movement of the
bolus over time, and quantifies the residual bolus in the
oropharynx, larynx and trachea, using radio nuclide material with
liquid or food, and a gamma camera. Although it detects aspiration
and reflux, it does not have a significant advantage over other
functional investigations as it does not image anatomy and
physiology, nor does it image the biomechanics of swallowing, and
the cause of aspiration cannot be determined.
101. Lingual pressure recording 101 Recently, three-bulb linear
manometric sensor arrays (Kay Elemetrics Workstation) have been
used to evaluate the timing and pressure patterns of the tongue
during the oral phase of swallowing. The small strain gauge
pressure sensors are attached to the palate).
102. Electromyography Surface electromyography (sEMG) measures
the amplitude (voltage) of swallowing muscle activity (from the
submental muscle group) from electrodes placed on the throat, and
is a method for identifying the onset of swallowing only. Activity
is recorded from any or all of the submental muscles during
swallowing, and they are variable in their order of activation both
within and between subjects. 102
