ENDOTRACHEAL TUBE

(ET Tube)

• Endotracheal tubes are curved tubes used for intubation

• Tubes were previously made up of latex (indian rubber) and those still available , currently plastic tubes (PVC) are preferred because of following advantages :

Disposable (less chances of infection) Hypoallergenic ( since latex allergy is fairly

comman) Transparent (easy visualization of blockage

ETT due to blood , pus , secretions

• THE ET TUBE HAS THE FOLLOWING COMPONENTS :

PROXIMAL END – 15mm adapter (connector) which fits to ventilator or ambu bag

CENTRAL PORTION – 1. A vocal cord guide (black line ) which should be

placed at the level of the opening of the vocal cords so that the tip of the ET tube is positioned above the bifurcation if the trachea.

2. A radio-opaque marker which is essential for accurate visualization of the position of the ET tube within the trachea by means of an X-ray

3. The distance indicator (marked in centimeters) which facilitates placement of ET tube.

4. A cuff- incase of cuff ET tube DISTAL END – has Murphy’s eye (opening in

the lateral wall ) which prevents complete blockage of ET tube incase the distal end is impacted with secretion , blood , etc.

TYPES

• ET tubes can be : - cuffed

- uncuffed• Cuffed ET tubes are used in children > 8 years• The cuff when inflated maintains the ET tube in

proper position and prevents aspiration of contents from GI tract into respiratory tract

• In children < 8 uncuffed ET tubes are used because the narrow subglottic area performs the function of a cuff and prevents the ET tube from slipping.

High volume Low pressure cuff

Low volume High pressure cuff

SIZE

• From 2mm to 16 mms (internal diameter ) The size of the tube can be determined by – internal diameter of ETT (mm) = age in years +4

4 Roughly the diameter of the childs little finger is

the same as that required for the ETT The following table gives an idea abpout the size

of ETT in different age groups.

AGE GROUP SIZE OF ET TUBE

PREMATURE BABIES 2 TO 2.5

FULL TERM BABIES UPTO 2 WEEKS

3 TO 3.5

FROM 2 WEEKS TO 24 WEEKS 4 TO 4.5

FROM 6 MONTHS TO 12 MONTHS

4.5 TO 5

Then increase the size of the ET tube by 0.5 cms for every 6 months rise in age so that at approximately 6 years of age size of the ET tube to be used is approximately 8 mms

USES For Mechanical Ventilation For Intermittent Postive Pressure Ventilation

(IPPV) During resuscitation Direct suctioning of trachea in meconium

aspiration In Epiglottits &life threatening croup In tetanus (however for long term bases,

tracheostomy is preferable) In diptheria In angioneurotic edema

COMPLICATIONS Mechanical trauma to tongue, teeth , palate ,

pharynx & larynx during intubation procedure Stimulation of posterior of posterior pharyngeal

wall leading to coughing , vomiting or vasovagal episode with resultant hypoxia , bradycardia.

Prolonged intubation may cause pressure necrosis of laryngeal structures leading to persistant hoarseness ( hence tracheostomy) is indicated in patients requiring long-term mechanical ventilation)

Pneumothorax.

AMBU BAG

• PARTS OF THE AMBU BAG PATIENT OUTLET (to which mask is attached ) ONE-WAY VALVE UNIT (just proximal to

patient outlet ) PRESSURE RELEASE VALVE Attachment site for manometer

size : the size of the bag varies depending on the volume ( ranges from 250 ml to 750 ml for paediatric use)

pressure release valves : are usually set to release at pressure of 30-35cms of water

at the end there are two inlets OXYGEN INLET : This inlet is attached to a tube

carrying oxygen from the source (central oxygen line or oxygen cylinder )

AIR INLET : if kept open the concentration of 02 is approx 40% FiO2. for the Fi02 to be near 90-100% , and oxygen reservoir should be attached.

MECHANISM OF VENTILATION

in the resting stage the ambu bag is filled with air . On squeezing the bag to initiate ventilation the one wave valve proximal to the patients outlet opens resulting in release of air , stored in the bag to the patient. On releasing the pressure the bag gets re-inflated with air. The patients exhaled air cannot re-enter the bag due to one wave mechanism of the valve at the patient outlet.

USES : for giving intermittent positive pressure ventilation