Laryngoscope

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A laryngoscope (larynx+scope) is a medical instrument that is used to obtain a view of the glottis.

Rigid laryngoscope

A rigid laryngoscope is used for direct laryngoscopy (visualizing the larynyx). It consists of a handle (incorporating two batteries) and an interchangeable blade with a bulb light source. The original blade was a straight Magill [[1]] and this design is still the standard pattern veterinary laryngoscopes are based upon; however the blade is difficult to control in adults and causes pressure on the vagus nerve, which can cause unexpected cardiac arrhythmias to spontaneously occur in adults.

There are many types of laryngoscopes. The favourite is the curved Macintosh blade whereas the Miller and Robertshaw blades are straight. The Macintosh blades sit behind the epiglottis and raise it out of the visual pathway thus exposing the glottis and vocal cords. Incorrect usage can cause trauma to the front Incisor teeth; the correct technique is to lift the chin forwards, not to lever backwards onto the teeth as inexperienced or untrained users attempt.

The Miller and Robertshaw blades are usually used for infants; the Miller can be seen in the picture to the right. These blades are inserted over the epiglottis, which in children is larger, thus the Macintosh technique is less effective.  

Direct laryngoscopy is done with the patient lying on his or her back; the laryngoscope is inserted into the mouth and flipped to the left to push away the tongue and inserted behind the epiglottis which lifts out of the way so that a view of the glottis is possible. This procedure is most often employed in tracheal intubation. It is extremely uncomfortable and is not performed onconscious patients except in dire emergencies.

It is performed to facilitate endotracheal intubation as part of general anesthetic or CPR cardiopulmonary resuscitation following a cardiac arrest.

The invention of the laryngoscope is hotly disputed; some claim it was invented by Manuel García, Professor of Music, and singing teacher for Jenny Lind, the "Swedish Nightingale"; whilst other medical giants (Morell Mackenzie writing in 1865) claim it was Benjamin Guy Babington.

Transnasal Flexible Laryngoscope

A transnasal flexible laryngoscope can be used for office-based diagnostics. The patient remains wide awake during the procedure, so the vocal cords can be observed during speech or singing. Surgical instruments passed through the scope can be used for performing procedures such as biopsies of suspicious masses.

References

• Yahoo Health on Laryngoscopy
• Transnasal Flexible Laryngoscopy (TFL)