The document discusses the physics and principles of fiberoptic image transmission using total internal reflection within glass fibers. It describes the components, optical and mechanical systems, working channels, and cleaning/sterilization of flexible fiberoptic laryngoscopes. The goal of fiberoptic intubation is to provide well-illuminated and magnified images of the airway for safe endotracheal intubation.

1. PRINCIPLES AND PRACTICE OF
FIBEROPTIC INTUBATION
Presenter : Dr. Bindu
Moderator : Dr. Ranjan R. K.

2. Physics of Fiberoptic Image Transmission:
a – angle of incidence
b – angle of reflection
Principle:
Law of total internal reflection: Light can be totally reflected
internally by the fiberoptic strand.

3. Degree of Reflection:
2. Angle of incidence of the light.
3. Refractive indices of the two transmission media.
Critical Angle: Angle at which parallel transmission occurs.
When the incident angle is increased beyond the critical angle
 total internal reflection of light occurs.
Light striking the boundary of a clad glass fiber will be internally reflected. Ic is the
critical angle. Light striking the boundary at an angle greater than the critical angle will
undergo total internal reflection.

4. Cladding protects the interface surface and increases transmission
efficiency
Fiberoscope consists of fibres arranged in bundles.
Each fibre Core or light transmission port.
Cladding material

5. Individual fibers are grouped
into a bundle in a honeycomb
pattern
Factors affecting decreased amount of light accepted by the
fiber:
2. Light scattered at the interface.
3. Light absorption by the core glass
4. Light entering the bundle at an angle lower than the critical
angle.
5. Packing fraction loss.
Packing fraction: Cross sectional area of the cladding material

6. Fiberoscope Components:
Components of a flexible fiberoptic laryngoscope:
b. Body : Tip deflection control lever Eyepiece
Focusing ring Working channel sleeve
b. Insertion cord : Fiberoptic bundles
Optical system
Mechanical system
c. Light transmission cord (Universal cord)

7. • Fibers are arranged in bundles in a coherent order.
• In a coherent fiber bundle – the arrangement of fibers in one end of the
bundle exactly matches the arrangement in the opposite bundle.
• In incoherent bundle – no correlation exists between the fiber
arrangement in the two bundles.
• They are used as light conduits  light guide bundles.
• Any breakage of illuminating fibres decreases the amount of light that
reaches the tip of scope. Breakage of optical fibres results in black
spots in the image because those pixels of data are lost.

8. Optical System:
An objective lens placed at the distal end of the fiberscope forms an
image on the distal end of the image bundle.
Since objective lens inverts the image the fiberoptic bundle is internally
rotated 180° which compensates for the image inversion.
This image is then magnified by an ocular lens placed in the eye piece.
The eyepiece contains a diopler adjustment to compensate for any
visual abnormality of the endoscopist. This results in a well illuminated
and magnified image of high resolution.

9. Mechanical System:
• Image bundles
• Illumination bundles
• Working channel All ensheathed in a tough
durable outer covering
• Angulation control wires
• Flexible distal joint system
Internal components and construction of the insertion
tube of the fiberscope.

10. Working Channels:
They run the length of the endoscope
Uses:
4. Suctioning can be applied for clearing of secretions.
5. Medications can be instilled into the airway.
6. Biopsy instruments for diagnostic procedures.
7. Instillation port
Angulation control wires:
• The distal end of the laryngoscope has a two way angulation system.
• Angulation wire runs the length of the fiberoscope from the control knob
through the metal bands and is fixed at the distal end of the endoscope.
• Tip deflection is produced by rotating the control knob thus exerting tension
on the angulation wire which inturn flexes the metal band.
• Flexible section of the distal end has a series of metal bands attached together by flexible
joints

11. Light Sources:
Two basic types:
• Low power halogen light source
• High power xenon light source.
Fibre optic laryngoscope with a battery operated light
source on the handle

12. Sterilization and Cleaning of the Flexible Fiberoptic Bronchoscope:
Routine Cleansing of the fiberoscope:
Step 1 Connect suction port to vacuum suction
Step 2 Aspirate approximately 200ml detergent solution through suction
channel
Step 3 Clear suction channel with cleaning brush
Step 4 Wipe shaft and valves with detergent-soaked sponge
Step 5 Aspirate approximately 200ml sterile water through suction channel
Step 6 Wipe shaft and valves with sterile water
Step 7 Proceed with disinfection / sterilization
Sterilization:
Ethylene oxide gas
Fiberscopes may be sterilized by this method at a temperature of 130°F
(54.4°C), pressure 20psi and humidity 50% for a period of 4-5 hrs.
Disadvantage: Time consuming

13. Routine Cleaning
Immediate cleaning of the fiberoptic bronchoscope and
valves with detergent solution followed by 20 minutes of
disinfection with 2% alkaline glutaraldehyde (cidex) or succine
dialdehyde solution. It is rinsed and the channel is flushed with
70% alcohol. The scope is then allowed to dry.
Storage of Fiberoptic Instruments:
To prevent the fiberoptic bundles from being bent or
broken, the laryngoscope is stored straight in a cylindrical tube
on the portable chart or stored horizontally within the drawer of
a mobile bronchoscopic cart or stored within the soft molded
foam of its carrying case.

14. REFERENCES:
• Anesthesiology Clinics of North America. The
Upper Airway and Anesthesia. Fiberoptic
Bronchoscopy.
• Miller’s Anesthesia 6th edition
• Clinical Anesthesiology- G.Edward Morgan