Equipments Used for Endotracheal Intubation

Equipments Used for Endotracheal Intubation

Laryngoscope

Laryngoscope is a tubular endoscope equipped with a blade and light bulb used to view the larynx and adjacent structures, most commonly for the purpose of inserting a tube into the trachea. Other purposes include placing a gastric tube, foreign body removal, and visualizing and assessing the upper airway. Rigid laryngoscopes commonly used in anesthesia practice are manufactured with separate detachable blade and handle. The light source is either a lamp attached to the blade or a lamp in the handle with a light guide in the blade. For a detachable handle and blade, the light source is energized when the blade and handle are locked in the operating position.

Is the part held in the hand during use (Figure 6.1). It provides the power for the light. Most often, disposable batteries are the power source. Handles with rechargeable batteries are available. Handles designed to accept blades that have a light bulb have a metallic contact, which completes an electrical circuit when the handle and blade are in the working position.

Laryngoscope Blades (Figure 6.2) come in different sizes (Table 6.2). This allows for the intubation of patients of various size and age. It is important to use a blade that is appropriate for the size and age of the patient. If the blade is too small or too large it may make laryngoscopy and intubation more difficult. A straight blade is made to pick up the epiglottis commonly used in children. A curved blade is made to fit into the area anterior to the epiglottis called the vallecula. A curved blade will indirectly expose the glottic opening, by picking up the epiglottis, when you perform laryngoscopy

Table 6.2 Appropriate Laryngoscope Size

Endotracheal Tube

Tracheal tubes are designed to provide a secure channel through the upper airway . The distal end lies in the mid to lower part of the trachea, whereas the proximal end lies outside the mouth or nose, where it is connected to an anesthesia circuit or other device. Tracheal tubes (TT) are most commonly made from polyvinyl chloride; standards govern TT manufacturing (e.g., American National Standard for Anesthetic Equipment; ANSI Z-79) to indicate that they had been implant tested to ensure nontoxicity.

Lengths are marked in centimeters, and internal diameters are indicated in millimeters. TT size is usually designated in millimeters of internal diameter or, less commonly, in the French scale (external diameter in millimeters multiplied by 3). The choice of tube diameter is always a compromise between maximizing flow with a large size and minimizing airway trauma with a small size.

An adult or adolescent female will usually require a 7.0 to 7.5 sized endotracheal tube (Figure 6.3). An adult or adolescent male will usually require a 7.5 to 8.0 sized endotracheal tube. Small adults may require a 6.0-6.5 sized endotracheal tube. Always check the cuff, ensuring it inflates and does not have a leak before insertion. When inflating the endotracheal tube cuff on adults, add just enough air to prevent an air leak. Do not over inflate the endotracheal tube cuff. This may lead to mucosal necrosis. By creating a tracheal seal, TT cuffs permit positive-pressure ventilation and reduce the likelihood of aspiration. Uncuffed tubes are usually used in children to minimize the risk of pressure injury and post-intubation croup.

There are two major types of cuffs: high pressure (low volume) and low pressure (high volume). High-pressure cuffs are associated with more ischemic damage to the tracheal mucosa and are less suitable for intubations of long duration. Low-pressure cuffs may increase the likelihood of sore throat (larger mucosal contact area), aspiration, spontaneous extubation, and difficult insertion (because of the floppy cuff). Nonetheless, because of their lower incidence of mucosal damage, low-pressure cuffs are more commonly recommended.

The endotracheal tube should be inserted so the cuff is passed beyond the vocal cords. For most adults the depth is approximately 20-22 cm. For the small adult it may be slightly less. For the very large adult it may be slightly more.

The size of the endotracheal tube should be based on the patient's age and size. Knowledge of the differences between the adult and pediatric airway is important (Figure 6.4 A and B).

Estimation of Endotracheal Tube Size in Children

• For children older than 2 years of age, the endotracheal tube can be estimated by: ( age/4 )+ 4 .
• A simple method of estimating the size of the endotracheal tube is to compare the diameter of the child's small finger to the diameter of the endotracheal tube. If they are the same size, then the endotracheal tube should be the correct size. It is still important to have an endotracheal tube that is 0.5cm smaller and a 0.5cm larger from the calculated one.
• You should have available an endotracheal tube size below and above what you estimate for the pediatric patient. For example, if you calculated a 4.5 sized endotracheal tube, a 4.0 and a 5.0 sized endotracheal tube should also be available. The formula for estimating the correct endotracheal tube size is only a guide.

Estimation of Endotracheal Tube Insertion Depth in Children

• For children under 1 year of age: age +weight in Kg
• Over 2 years of age: 12 + Age/2
• Or multiply internal diameter of the endotracheal tube by 3 to estimate insertion depth.

Pediatric endotracheal tube recommendations

• An uncuffed endotracheal tube (Figure 6.4 B) is recommended for children under 8 years of age. The reason is to decrease pressure to the cricoid cartilage, reducing the incidence of post extubation croup.
• The endotracheal tube should have a leak at 15-20 cm H2O. If you cannot check this with a pressure manometer, you should ensure that you have a slight air leak when ventilating the patient. The air leak should not lead to difficulty in ventilating the patient. If you are unable to generate 15 cmH2O, then the endotracheal tube may be too small. If you have absolutely no air leak, then your endotracheal tube may be too large for the patient.
• A child sized cuffed endotracheal tube may be used for emergency surgery when the child has recently eaten. This will help protect against aspiration. As you fill the endotracheal tube cuff with air, you should just put enough air to stop an air leak as you ventilate. You will need to monitor the patient closely for post intubation croup in the postoperative period.

A Magill's Forceps

A Magill´s forceps is helpful for endotracheal tube manipulation if difficulty is encountered in positioning the endotracheal tube (Figure 6.5).

Figure 6.5 Magill’s intubating forceps

Be careful not to damage the endotracheal tube cuff with the forceps. Magill's forceps are often used to manipulate the endotracheal tube during a nasal intubation, nasogastric tube insertion and foreign body removal.

A Stylet and Bougie or ETT Introducer

A stylet is designed to fit inside the tracheal tube and help in creating a shaped, stiff endotracheal tube (Figure 6.6). The tip of the stylet should not be allowed to protrude beyond the end of the endotracheal tube. The bougie (Figure 6.7) is flexible endotracheal tube introducer when the laryngeal opening is not fully visible (epiglottis only view) and controls the direction of the endotracheal tube during insertion. The tip of bougie should protrude through the ETT to direct the endotracheal tube through the larynx (Figure 6.8).

A protruding stylet may cause trauma to the patient's airway. Do not force the endotracheal tube when placing it with a stylet. This may cause trauma to your patient. The proper procedure for using a stylet is to have an assistant remove the stylet once the tip of the endotracheal tube is just past the vocal cords. Hold the endotracheal tube firmly while your assistant removes the stylet This will prevent accidental extubation of the patient. Once the stylet is removed, advance the endotracheal tube to its appropriate depth.