Airway

▪Laryngeal Mask Airway and Endotracheal Tube

Laryngeal Mask Airway and Endotracheal Tube

Weight	LMA	Max LMA Cuff	Max ETT
Up to 5 kg	1	4 cc	3.5 mm
5-10 kg	1.5	7 cc	4.0 mm
10-20 kg	2	10 cc	4.5 mm
20-30 kg	2.5	14 cc	5.0 mm
30-50 kg	3	20 cc	6.0 mm cuffed
50-70 kg	4	30 cc	6.0 mm cuffed
70-100 kg	5	40 cc	7.5 mm cuffed
> 100 kg	6	50 cc	8.0 mm cuffed
Cuff pressure 17-23 mm Hg normal; pressure > 25 = ischemia.

LMA Fastrach^TM Guidelines

Weight	LMA	Max Cuff
30-70 kg	3	20 cc
70-90 kg	4	30 cc
> 90 kg	5	40 cc
A 6.0-8.0 ETT can be fit through a Fastrach^TM tube.

	Adult	Child
Carina:	T4-6	T5

LMA

Latex-free.

20-cc syringe for pilot balloon.

Lubricate only post-pharyngeal surface to avoid blockage of aperture or aspiration of lubricant. Black line on tube oriented toward upper lip. Look for slight outward movement of tube upon LMA pilot balloon inflation.

Look for presence of oval swelling in neck around thyroid and cricoid area.

With proper placement the LMA lies in supraglottic position in hypopharynx.

Advantages: Less stimulating than ETT, ease of placement, used in difficult airway scenario.

Disadvantages: Cannot prevent regurgitation and aspiration or laryngospasm.

Contraindications: Pregnancy, GERD, laryngoscopic or emergency surgery, morbid obesity, hiatal hernia, full stomach,Trendelenburg position.

Oral RAE® tube: A preformed, U-shaped ETT that bends at level of teeth so it exits mouth away from the surgical field.

Wire-reinforced ETT: Armored tubes that resist kinking.

MLT (microlaryngeal tracheal tube): Same length as an adult tube but sizes are smaller; stiffer, and less prone to compression.This tube has a large, high-volume, low-pressure cuff sized 4.0-5.0-6.0 mm.

Lita^TM ETT: Injection port and orifices above cuff for instillation of LA.

Miller blade can cause bradycardia because underside of epiglottis is innervated by vagus nerve.

▪Airway Assessment

Atlanto-occipital extension: normal > 35% (between atlas and occipital condyles).

Oral opening: normal 5-6 cm; less than 3 cm indicates difficulty.

TMJ: horizontal length of mandible; normal 9 cm.

Thyromental distance: between the lower border of the mandible and the thyroid notch with the head fully extended; normal > 6.0-6.5 cm (approximately 3 fingerbreadths).

Cormack Laryngoscopic Grades

Cormack airway grades.

I – Glottis is fully visualized.

II – Landmarks are identifiable but laryngeal aperture is partially obscured.

III – Laryngeal aperture is almost completely obscured.

IV – Unable to visualize the laryngeal aperture.

Mallampati: A clinical sign to predict difficult tracheal intubation, the Mallampati Classification is based on the structures visualized with maximal mouth opening and tongue protrusion in the sitting position. It relates tongue size to pharyngeal size, so the
amount of the posterior pharynx you can visualize is important.

Class I: Soft palate, tonsilar pillars, uvula.

Class II: Tonsilar pillars and base of uvula hidden by base of tongue.

Class III: Soft palate visible.

Class IV: Soft palate not visible.

Anatomy of the Larynx

Epiglottis: At level of C3 in children; at level of C5 in adults.

Larynx: Located at C4 to C6 cervical vertebrae in adults.

The glottis is the opening of the larynx, which is the smallest portion in the adult airway.The cricoid is the narrowest part of a child’s airway.

Laryngeal Cartilages