Cuffed vs. Uncuffed Endotracheal Tube In a Child: Pros and Cons

When intubating children, the question always arises whether to use a cuffed vs. uncuffed endotracheal tube (ETT). Historically uncuffed ETTs have been used when the child is less than about 8 years old. However this trend is changing with the use of cuffed tubes becoming more common. Why is it that we can get away with using an uncuffed ETT in a young child, but not an adult? Are there advantages and disadvantages to each? The answers comes from understanding some of the anatomical differences between children and adults.

Author’s Note: This post was originally published in March 2015 as “Should I Use A Cuffed or Uncuffed Endotracheal Tube In A Child”, and has been completely revamped and updated for accuracy and comprehensiveness.

Anatomical Differences Young Child vs Adult

The ideal endotracheal tube provides an effective airway seal and precise ventilation control while minimizing airway trauma. But you must consider anatomical differences when selecting between cuffed vs. uncuffed endotracheal tubes.

Children are not small adults. Pediatric anatomy differs in 4 main ways: size, composition, position, and shape. We can often tell how old a child is simply by looking at head size, facial characteristics, neck length, and body shape. It should not be surprising that the inside of the child is changing as well. Infants, who have the greatest anatomic differences, have the greatest risk for airway complications.

comparative photos of infant, toddler, and adult larynxes - a consideration in using cuffed vs. uncuffed endotracheal tubes

The smallest diameter of the infant airway is the relatively round opening through the cricoid ring, not the triangular vocal cord opening as in the adult.

The pediatric larynx is shaped differently from the adult larynx. In infants and children, the airway is wider above the glottis and narrows below it at the subglottic region, creating a funnel-shaped passage. This anatomy increases the risk of airway obstruction when subglottic edema occurs, as in croup or after intubation trauma.

Illustration of infant vs adult larynx showing that the infant/toddler larynx is funnel shaped, and smaller at the bottom -- a consideration in using cuffed vs. uncuffed endotracheal tubes — Adult larynx on the left (a), Infant/toddler on the right (b)

Higher Risk from Swelling

Avoiding tracheal trauma and swelling is important. Because the pediatric larynx and trachea are so small, even minor swelling can obstruct the airway. In an adult with a 10-mm trachea, 1 mm of circumferential swelling reduces cross-sectional area by 44% and triples airflow resistance. In an infant with a 4-mm trachea, the same 1-mm edema reduces area by 75% and increases resistance 16-fold. Conditions such as croup, or even a coin stuck in the esophagus that compresses the soft trachea, can therefore severely impair breathing in infants and toddlers. Avoiding trauma and any resultant swelling in the pediatric airway is therefore important.

Illustration showing a comparison of effects of 1-mm circumferential edema on adult and infant airways. — Comparison of effects of 1-mm circumferential edema on adult and infant airways.

Obtaining a Seal Around the Endotracheal Tube

Positive pressure ventilation depends on providing enough pressure to inflate the lungs. If there is a break in the pressure seal, such as through a leak around the endotracheal tube, then ventilation may be inadequate. The air takes the path of least resistance back out the mouth, rather than inflating the lungs. In addition, the patient can potentially aspirate around the tube through the gap.

Cuffed vs. uncuffed endotracheal tubes obtain a pressure seal differently. In adults the glottic opening between the vocal cords is the smallest diameter of the larynx. The airway below the cords is bigger than the ETT and the cuff on the ETT seals the gap.

Illustration: difference in anatomy between adult and the infant or toddler. cuffed vs. uncuffed endotracheal tubes obtain a seal in different ways. — The difference in anatomy between adult and the infant or toddler, explain why an uncuffed endotracheal tube is an option in small children.

In infants and children younger than about 8 years the cricoid ring is the narrowest part of the young child’s airway. A properly sized round uncuffed tube could seal this opening without a cuff. Providers believed that avoiding a cuff reduced pressure on the trachea and lowered the risk of subglottic injury and postextubation croup.

The optimally sized uncuffed ETT lets you ventilate while allowing a leak at about 20 to 25 cm of water pressure. This pressure leak value minimizes the risk for ischemia from compression of the tracheal mucosa. A leak at a lower pressure makes controlled ventilation difficult and increases the risk for aspiration.

Children older than 8 years need a cuff to seal the trachea, because by this age the triangular vocal cord opening has become the smallest diameter.

Uncuffed tubes do not eliminate the risk of postextubation croup. More recent research suggests that the cricoid ring is elliptical rather than round. As a result, a round, uncuffed endotracheal tube may still exert excessive pressure on parts of the tracheal mucosa, even when an air leak is present. This has weakened the rationale for routine use of uncuffed tubes. At the same time, most pediatric cuffs are now low-pressure designs.

Advantages of Cuffed Endotracheal Tubes

Cuffed low-pressure, high volume ETTs are increasingly used in young children because they offer distinct advantages.

Provide more reliable delivery of precise tidal volumes during mechanical ventilation
Provide better protection against aspiration
Allow higher ventilation pressures in patients with poor pulmonary compliance
Reduce the need to exchange the tube if the initial tube size is too small
Improve the accuracy of ventilation and tidal volume monitoring
Reduce anesthetic gas leakage during anesthesia, decreasing operating room pollution
Reduce fire risk in surgery around oropharynx

Disadvantages of Cuffed Endotracheal Tubes

On the other hand, there are potential disadvantages to using cuffed tubes in small children.

Cuffs take up space and force use of a tube size one-half to one size smaller.
There is a higher risk of plugging the smaller lumen with secretions.
Suctioning smaller tubes is more challenging.
Smaller diameter tubes have greater resistance to breathing:
ex: a size 4 ETT has a 59% higher resistance and work of breathing compared with size 5.

Comparative Risk of Tracheal Trauma: Cuffed vs. Uncuffed Endotracheal Tubes

A second concern about cuffed ETTs in small children is the risk of mucosal injury, post-extubation croup, and later tracheal stenosis. Older cuffed ETTs were high-pressure, low-volume designs that concentrated pressure on a small area of mucosa and could impair capillary blood flow. Newer low-pressure, high-volume cuffs distribute pressure over a larger surface area. Studies of these modern cuffs have found no increase in post-extubation croup or long-term complications, such as tracheal stenosis, compared with uncuffed ETT.

Illustration of the comparison of muscosal pressure of cuffed vs. uncuffed endotracheal tubes — Low-pressure, high volume ETT cuffs (right) exert less mucosal pressure because compression is spread over a larger area then high-pressure, low volumes cuffs (left)

Safe Use of Cuffed Endotracheal Tubes

Choose a cuffed tube one-half to one size I.D. smaller than calculated size to allow room for the volume of the uninflated cuff. Check for a leak before inflating. You will sometimes find that you don’t need to inflate the cuff to obtain an adequate seal.

With head extension, the endotracheal tube tip rises within the trachea, which may move the cuff into the subglottic region and increase the risk of injury to the subglottic mucosa and recurrent laryngeal nerves. If the head will remain extended for a prolonged period, the tube may need to be repositioned.

Illustration showing how the tip of a cuffed or uncuffed endotracheal tube moves up and down with head movement in a child. — The tip of the ETT will move significantly with head movement in the child. Neck extension can lead to extubation if the tube is not inserted to the correct depth.

Precautions

You can use a cuff in infants and children younger than eight if you follow precautions:

Choose tube size, insertion depth, and stabilization carefully.
Ensure the cuff is below the cricoid ring to avoid pressure to the recurrent laryngeal nerves.
Do not overinflate the cuff beyond 20–25 cm H2O, as excessive pressure can injure the mucosa. Instead, inflate only to the minimum seal—the cuff volume at which the air leak just stops during constant pressure of 20–25 cm H2O. Monitor cuff pressure when possible.
During anesthesia, N2O can diffuse into the cuff and progressively increase its pressure. Check cuff tension periodically and remove small amounts of air as needed to maintain a minimum seal.
During air transport, cuff volume expands at altitude and can increase mucosal pressure, so remove air as needed to maintain a minimum seal. As the aircraft descends, you may need to add a small amount of air as cuff pressure falls. Filling the cuff with saline avoids these pressure changes, but because much less saline is required than air, take care not to overinflate the cuff.

Other Caveats

Deciding Initial Depth of ETT Insertion

Ensure the cuff is below the cricoid ring to avoid injury to the recurrent laryngeal nerves. When dealing with a short trachea, optimal vs suboptimal depth can be less than a cm. The most familiar formula for calculating ETT depth applies to children older than 2 years. Note: Depth at the lip (ATL) calculations are in centimeters.

Depth ATL = (age in years/2) + 12

For infants and children younger than 2 years of age, calculate ETT depth by using the formula:

Depth ATL = Calculated uncuffed ETT interior diameter × 3

Formulas for ETT depth of insertion have been clinically validated for neonatal patients weighing more than 750 g up to 4 kg.

Depth ATL = weight (kg) + 6

Although these formulas are reasonably accurate, you still must verify bilateral breath sounds as children of the same age can vary much.

ETT Length

The Hagen-Poiseuille equation also shows that resistance increases as tube length increases, so a shorter ETT has less resistance to breathing. It’s common practice to cut the length of the endotracheal tube in an infant so that it extends no more than 1-2 cm from where it exits the mouth.

I recommend cutting the tube and reinserting the adapter before intubation to avoid post-intubation manipulation, which can increase the risk of tube misplacement.

Key Takeaways

Cuffed endotracheal tubes are becoming more common for young children due to anatomical differences compared to adults.
Pediatric anatomy, such as a funnel-shaped airway, increases the risk of airway obstruction and complications.
Cuffed tubes provide better ventilation, aspiration protection, and reduce the need for tube exchanges.
However, cuffed tubes can lead to injury and have a smaller lumen, causing higher breathing resistance.
For children under 8, cuffed endotracheal tubes can be used if precautions are taken to avoid airway trauma.

You should consider using a cuffed tube for children at risk for aspiration and children who might need higher inspiratory pressures. Read more about intubating infants and small children in Intubating An Infant or Toddler.

You can read my review article on common airway problems in pediatric airway management here:

10 Common Pediatric Airway Problems — And Their Solutions

The Airway Jedi