EMmedonline

The endotracheal tube which is commonly used is made of polyvinyl chloride. Other kinds of material used for ET tube is silicone rubber, flexometallic

There are two different types of endotracheal tube

• cuffed endotracheal tube

  • High pressure low volume cuff

  • Low pressure high volume cuff

• uncuffed endotracheal tube

• SPECIAL TYPES OF TUBE

• Preformed tubes

• Spiral embedded tubes

• Endotrol tube

• Larryngectomy tubes

• Tubes for use with lasers

• Intubating laryngeal mask tracheal tube

• Double-lumen tubes

Parts of ET Tube

• Connector

• pilot ballon

• cuff

• murphy eye

• bevel

The ET tube has a internal and external diameter.

The internal diameter determines the amount of air flow. Depending on the internal diameter the size of the tube can be from 2.5mm to 9.0mm.In adult male usually a 8mm & females a 7mm tube is been used.

External diameter depends on the internal diameter and thickness of the tube (depends on manufacturer) . In adults the external diameter is limited by glottic aperture whereas in childrens it is limited by subglottic area.

The tube is lined by a radiopaque material which helps in the confirmation of the tube by xray.

Murphy eye : it is a hole cut on the wall opposite to the bevel which helps to maintain some amount of continuous flow of air when the bevel of the lumen is occluded.

ET tube lacking murphy's eye is called magills forceps.

The angle of bevel is acute angle between the bevel and logtitudinal axsis of tracheal tube. The tube is introduced from right & larynx is easier to visualise the bevel facing to left.

The tube when manufactured is sterile.

The tube material is stamped Z-79 or IT indicating that tube is free of toxic or irritating substance.

Before the use of tube the cuff should be checked for any leak by inflating . A cuff pressure of 20-25mmof hg is essential to offer a good protection of the airway. A cuff pressure of more than 25-35mmhg may lead to ischemia of the tracheal mucosa.

In childrens a uncuffed endotracheal tube is used because of narrow glottic area.

 

SELECTION OF TUBE SIZE

In adult male usually a size 8 is used incase of females a size 7 is used . This is because in womens larynx is generally smaller and the glottic aperture limits the size of the tube.

Tube size can be estimated from the formula

• ID = (age +16 ) / 4.

or

• <6yrs :age in years/3 + 3.75

• >6yrs :age in years/4 + 4.5

or

• ID = 3mm for 3mnths age and younger

• 3.5mm for those from 3-9 mnths of age

or

• Uncuffed ET ID =4 + (age/4)

• Cuffed ET tube ID = (3.5 + age/4)

ANGLE OF MOUTH

• Length in cm = age/2 +12cm

• Lenght in cm= weight in kg/5+12cm'

• Lenght in cm = Height in cm/10 + 5cm

SPECIAL TYPES OF ET TUBE

Armored tube or spiral embedded tube

This tube is reinforced by a spiral wire to reduce kinking or collapse . They are useful when a endotracheal tube is placed in a tracheostomy or a laryngectomy stoma to provide airway. This may also be useful in head and neck or neurosurgical procedures where kinking of the tube is a strong possibility.

Performed tubes

• Most common type of performed tube is RAE (ie. Ring Adair Elwin tube)

• These are tube that allows the endotracheal tube, once placed, to be angled away from the face to facilitate access during surgeries around the head and neck.

• RAE tubes come in oral and nasal versions and may be cuffed or uncuffed .

Coles tube

• It is an uncuffed tube.

• Patient end has a smaller diameter than the shaft.

• Used for neonatal resuscitation.

Laryngectomy tube

• They have J configuration at the patients end.

• They are designed to be inserted in tracheotomy.