LARYNGOLOGY SEMINAR
Laryngeal mucociliary function
R3 楊宗霖
Physiological aspect of laryngeal epithelium
/ epithelium
pseudostratified ciliated epithelium: upper part of nasopharynx, larynx
stratified squamous epithelium
pharyngeal surface of epiglottis
upper half of laryngeal surface
portion of ventricular fold
true cord
/ mucous coat the respiratory passage
secreted by individual goblet cell
to keep air moist and trap small particle
/ action of cilia: to clear the respiratory passage
200 cilia on each epithelial cell
cilia : in sol (the same length): 5-100 microns
above cilia: mucus gel
beating frequency: 10-20/s
power stroke
- lower respiratory airway: beat upward
- nose: beat downward
- make the mucus to move at low velocity: 1cm/min
mean cilia beating frequency: 7.8 + 1.6 Hz
Viscoelastic property of airway mucus
/ solid and liquid property
/ viscoelastic: determined in transient & dynamic
/ factors: mucus content
pH, added salts, serum protein, DNA
/ alter epithelium ion & membrane permeability
/ Experimental model
- small animals: frog palate, excised bovine trachea, rodent models
- large animals: dog & sheep
- mucus samples were analyzed by magnetic rheometry
2001-10-24
Radioisotope measurement of the velocity of tracheal mucus
/ radioisotope scannig technique
repeated scanning 2min
modified rectilinear scanner
calculation of velocity
/ solution of stannous phytate
labeled with Tc99m, introduced into lower trachea
/ general methods
by external radiation detector: gamma emitting isotope
radioactive albumin microsphere, Tc99m, lat & AP scan
same method as Quinlan in nasal mucociliary measurement
injected through CT membrane
Mucociliary function measurement
/ laryngeal foreign body-> mucociliary blanket-> pharynx -> swallowing
/ 1967 Ewert & Martensson, first in human
/ Results
1. human
clearance rate: within 30 min
2. calf, in vitro, use carbon
trachea transport velocity: 4.2 mm/min
3. in rabbits
transport velocity: 3.59+1.23 mm/min
4. in dogs
trachea transport velocity: 10.4 + 2.2 mm/min
/ clearance mechanism
mucociliary clearance, cough,
peristalsis,
two-phase gas-liquid flow
alveolar clearance
/ reversed trachea study in rabbit
inverted trachea: cilia move in another direction
ciliary direction is irreversibly determined
no influence in life
/ cough in regional mucus transport
cough, forced expiration: both significant clearance
document move of secretion by cough
cough clearance: back up of mucociliary clearance
Retention of the particles
/ deposition mechanism:
inspiratory flow rate and particle size
/ main physical mechanism governing deposition of particles
impaction, sedimentation, and diffusion
/ particle velocity varies with both flow rate and airway diameter
increase as flow rate increase and diameter narrow
/ particle size distribution
- estimation: mass median aerodynamic diameter
- actual measurement
particle > 6 μm: deposit in oropharynx
particle between 2-6 μm: in central airway
particle less than 2 μm: in the peripheral airway of lung
particle less than 1 μm: resp. bronchioles, surface of alveolar surface
/ FPF: fine particle fraction: define as less than 6 μm (use in aerosol)
/ retention of particle (in dogs)
clearance of submicron particles is very nearly 24 hrs, 92% within 3hrs
Coordination of mucociliary transport in human trachea
and intrapulmonary airway
/ measurement
1.tracheal mucus velocity (tracheal mucociliary transport rate)
2.lung clearance
/ experiment
iron oxide aerosol, tagged with Tc99m, vertically aligned rectangular NaI detector
pulse aerosol delivery system
/ correlation with rate of lung clearance
Medical effect
1. mucociliary
/ decrease: anticholinergic, aspirin, anesthesia, benzodiazepine
/ increase: cholinergic, sodium cromoglycat, hypertonic saline, water aerosol
/ no effect: anti-adrenergic, fusemide
/ no effect or increase: adrenergic agonist, steroid
/ anesthetic: significant decrease mucus transport
2. cough clearance
/ increase: amiloride, rhDNase, N-actyl-cystein, hypertonic saline
/ decrease: anti-cholinergic,
/ no alter: nertral saline, brohexine, ambroxol
Effect of hydration and physical Tx on tracheal transport velocity
/ quntitative mesaurement of tracheal transport velocity
/ Albumin microspheres, 5-7 micro-m, labeled with Tc99m
gamma scintillation camera
/ tracheal transport velocity
dehydration: decrease
rehydration: recovery
postural drainage: increase
chest purcussion: increase
/ clearance decrease: in mucus depleted bovine trachea
References
1. Armengot M, Garin L, Barona R, Montalt J, Basterra J. Laryngeal mucociliary
transport: normal values and under the influence of anesthetics. An experimental
study in rabbits. Acta Otorhinolaryngol Belg. 1994;48(1):41-4.
2. Bak-Pedersen K, et al. Subepithelial mucous glands in the adult human larynx.
Studies on number, distribution and density. Acta Otolaryngol. 1986;102:341-52
3. Delaere PR, Liu Z, Delanghe G, Gyselen K, Jorissen M, Feenstra L. Mucociliary
clearance following segmental tracheal reversal. Laryngoscope. 1996;106(4):450-6.
4. Ho JC, Chan KN, Hu WH, Lam WK, Zheng L, Tipoe GL, Sun J, Leung R, Tsang
KW. The effect of aging on nasal mucociliary clearance, beat frequency, and
ultrastructure of respiratory cilia. Am J Respir Crit Care Med. 2001;163(4):983-8.
5. Min YG, Lee KS, Yun JB, Rhee CS, Rhyoo C, Koh YY, Yi WJ, Park KS.
Hypertonic saline decreases ciliary movement in human nasal epithelium in vitro.
Otolaryngol Head Neck Surg. 2001;124(3):313-6.
6. Jorissen M. Correlations among mucociliary transport, ciliary function, and ciliary
structure. Am J Rhinol. 1998;12:53-8.
7. Camner P. How important is mucociliary clearance? Exp Lung Res.1988;14:423-9.
8. Pariente R. Related Articles Therapeutic aspects of mucociliary clearance.
Biomed Pharmacother. 1988;42(8):521-4.
9. Bridger GP, Proctor DF. Laryngeal mucociliary clearance.Ann Otol Rhinol
Laryngol. 1971;80:444-9.
10. Bridger GP, Proctor DF. Mucociliary function in the dog's larynx and trachea.
Laryngoscope. 1972;82(2):218-24