Cuffed vs non‐cuffed endotracheal tubes for pediatric anesthesia

The physician undertaking pediatric anesthesia or management of the critically ill child in the pediatric intensive care unit (PICU) has great potential to cause harm to the child. Over many years, routine management of the pediatric airway has become a relatively safe undertaking and this has been achieved through the worldwide development of the speciality of pediatric anesthesia and intensive care. Any future development needs to acknowledge the large body of developmental work from past that has provided reproducible safe practice. Change must not be for change itself, and at the forefront of our practice must be the desire to provide optimized care that is evidence-based as far as possible. New techniques should be evaluated and adopted only if there is substantial evidence that innovation will be beneficial in the widest sense. This includes not only direct patient benefit but also the wider medico-economic arguments. The ‘pro and con’ for the direct medical benefits of cuffed vs uncuffed tubes in children remain finely poised, but the medico-economic arguments are irrifutable: cuffed tubes remain many times more expensive than uncuffed tubes and are likely remain so. On this basis alone it can be hard to justify the routine use of the cuffed tube provided equipoise between the two techniques remain. In contrast, on an individual basis there may be strong arguments in favor of selecting a cuffed tube provided there is justification. While enthusiasts of the cuffed tube continue to promote their potential benefits, the majority of pediatric anesthetists worldwide continue to safely use the uncuffed tube on a daily basis and find it hard to justify the large extra costs needed to change their practice when the benefits remain largely unproven. In this, the first in a new series of pro–con debates in Paediatric Anaesthesia we will examine the arguments for and against their use from the perspective of two expert views, with the goal that this will help the reader make up their own mind of whether to reconsider their current practice. Toni Weber Deutsches Kinderherzzentrum Sankt Augustin, Arnold Janssen Str. 29, D 53757 Sankt Augustin, Gemany A cornerstone of good medicine is maintaining safety, simplicity, and effective practice. Ignoring these basic principles can lead to unforseen problems which may not be immediately obvious. Examples of how development may lead to unforeseen complications lie in the highly regulated aircraft industry. An aircraft is a highly complex device, but it can also be regarded as the total the sum of many simple effective solutions. When the new generation of mainly computer-assisted civil airplanes were introduced in the late 1980s it met with substantial critisism of the new so called fly by wire philosophy (invented to reduce cockpit personnel), which led to substantial changes at the human–machine interface. Those changes led to a series of unforeseen events and incidents (1). However until 1994, not a single cause of an accident could be adressed to the machine itself. The reasons for critical incidents were in general problems at the human–machine sytem interface. Similarly in modern anesthesia: the elaborate equipment and monitoring systems have been designed to make our job easier and safer. However, the underlying technology and the machine–human interface is necessarily more complex especially in the need to add advanced skills such as ultrasonography (for transesophageal echocardiography or central line placement). This, like the example with the aircraft industry may lead to errors at the interface in that while the machine and human work correctly at an individual level, errors of decision may be made from misinturpretation at the interface. The development of the cuffed pediatric endotracheal tube into pediatric practice, has added a relatively new and ‘simple’ feature to an established piece of anesthetic equipment. The change to the device is in itself minor and has precedent in the long-term use of cuffed endotracheal tubes (ETT) in adults, but the application within pediatric anesthesia leads to quite complex changes in the ‘interfaces’ between patient, ventilator, and the anesthetist. Key concerns include: The need to use a smaller internal diameter (ID) tube in order to place the cuff, The need for additional monitoring and adjusting of cuff pressure The potential morbidity from the cuff by pressure, The potential for innapropriate tube placement or cuff herniation. Intubation with an ETT (whether cuffed or uncuffed) that is too large can lead to laryngeal damage, tracheal damage and sublottic stenosis with significant long-term morbidity which in the most extreme cases may require tracheostomy and laryngeal or tracheal reconstruction. Initially high pressure applied on the mucosa from an oversized tube or an inapropriately used tube cuff leads to local ischemia followed by deep ulceration of the perichondrium or even into the cartilage. This leads to secondary submucosal collagen formation and scar tissue which emerges from maturing and thickened connective tissue. Subsequently a slow contraction from the scar tissue results giving rise to glottic or subglottic stenosis. Some areas appear more vulnerable than others and a particular at risk area is the inner surface of the cricoid cartilage, in the area of the posterior lamina (2),. Additional risk factors for this pathology include duration of intubation (longer than 25 days), repeated intubations and excessive movement of the patient. Comorbidity such as sepsis, infection, chronic illness, or chronic inflammatory disease may also influence the outcome (2). The nature of the pathophysiological process is supported by an earlier neonatal study published 11 years earlier which also describes progressive changes within clearly defined areas in the larynx associated with intubation (3). While the authors doubted that prolonged intubation alone produced subglottic stenosis they did conclude that severe damage to the laryngeal cartilage is an early complication of the intubation procedure together with other individual patient factors. One of the obviously avoidable factors is excessive mucosal pressure either from an over-large uncuffed endotracheal tube (UTT) or an inflated cuff in a cuffed endotracheal tube (CTT). The overall incidence of intubation trauma in the pediatrics is significant with the vast majority of problems (82%) being ascribed, based on endoscopic examination, to an excessively large ETT rather than the intubation procedure itself (4). Longer-term, the incidence of subglottic stenosis has been reported as between 0 and 8% (5-7) with a large series of 3 000 critically ill patients having prolonged intubation without any developing aquired subglottic stenosis. The adoption of a CTT does not protect the patient from airway trauma. Over a 10 year period (1987–1997) Holzki reported four severe laryngeal injuries caused by CTT on the basis of a screening program documenting postintubation stridor of clinical relevance. Four years later the same author reported six similar lesions in 1 year (8). Concerns have also been raised about the potential for tube misplacement. The distance from glottis to carina is relatively short and the design of some cuffed tubes has been such that when the cuff is correctly placed just below the vocal cords, the tip of the tube is already at the carina (9). Meticulous selection of the ETT remains the mainstay of good practice with intellegent use of formulae based on age. The traditional formulae of 4 + age/4 has given way to 4.5 + age/4 which may reflect the increased growth profile of contemporary children and the reduced wall thickness of modern ETT compared to the historic rubber tubes.(the tube size refers to the intenal tube diameter). It is also worth noting that the formula does only apply from age 2 years and above. In practice, the formulae acts only as a guide in that the more experienced practitioner effectively reduces the number of attempts of intubation by simply visualizing the glottic opening at the first laryngoscopy and then estimate the right tube size, a technique which is widely and effectively adopted in our institution. A recent study comparing cuffed and uncuffed tubes in pediatric practice noted a 23% reintubation rate in the uncuffed group (10). However, selection of the initial tube size was based on a formula alone and this does not reflect realistic clinical practice: An added complexity is that even today not all ETT have the same wall thickness. For example the outer diameter of a Portex ID 3.5 is 4.8 mm and in contrast the outer diameter of a Vygon 3.5 ID is 5.1 mm. It could be argued that this becomes less important if a cuffed tube is being used, but this in itself introduces an additional problem. In general, the cuffed tube selected for intubation will be smaller than the uncuffed tube because cuffed tubes are manufactured with thicker walls and the cuff ‘adds’ the additional diameter to form the seal with the trachea. As a result choosing a cuffed tube necessitates using a tube with a smaller ID. While this may be of less relevance in the older child it has been pointed out that the difference of a 3.0 mm tube compared to a 4 mm tube represents a three-fold increase in airway resistance leading to potential problems increased work of breathing and the problems with retenion of secretions and even airway occlusion (11). In the long history of the UTT the potential disadvantages of undersized tubes have been well documented. These include variable airleak, difficulties in effectively ventilating the patient with lung disease or allowing atelectasia, environmental contamination of anesthetic gasses, risk of aspiration, and difficulty in accurate masurement of endtidal CO2 concentration. Despite these potential problems, the use of the uncuffed pediatric endotracheal has remained popular and with the many years of usage pediatric anesthetists have learnt to overcome these shortcomings effectively. While tight fitting tubes confer benefit in patients with critical ventilation (such as pulmonary hypertension) the safe pressure in the child with cardiac compromise remains unknown. Dullenkopf suggested that cuff pressures below 25–30 cm H2O should be accepted (12) in children with a compromised cardiovascular system, but this was not evidence-based and accepting a leak brings in to question the whole issue of whether a cuffed tube should have been used In our institution with a large pediatric surgical and cardiac service we use a throat pack on occasions to reduce the number of repeated intubations with uncuffed tubes to below 5–10% which allows good control of advanced ventilatory modes with modern ventilators that can adjust for leaks. Many of the studies on cuffed vs uncuffed tubes are undertaken by enthusiasts and the conclusions of these studies are open to critisism and claims of bias. For example Deakers (13) compared two groups of children in an intensive care enviroment were the patients intubated with an uncuffed tube had a mean of 2.5 years of age while the children intubated with a CTT have been a mean of 8.1 years old. In the paper of Khine in which the outcome measure was postintubation stridor (10) the intubation time was just about an hour, the number of neonates was not mentioned and it could be argued that there was substantial study bias in terms of meticulous control of cuff pressure and tube position. Up to the year 2005 there was only one randomized and controlled trial on cuffed vs cuffed tubes (10). Most of the other available studies have concentrated on postextubation stridor which does not appear to be related to incidence of subglottic stenosis (14, 15). The sheer numbers of manufacturers making cuffs, the types of design of cuff (high-volume low-pressure vs the of of the tube design have been In one study by a total of tube types from four manufacturers were which significant and to this out in clinical practice. The authors at the time that most tubes were designed in the age group and that a more work was a majority of pediatric anesthetists in a recent that benefit could be from cuffed tubes all of the anesthetists and of the reported that they did not the pressure, when using a cuffed results were reported in a study by pressures not remain to and local factors cuff and anesthetic cuff pressure mucosal damage while reduced pressure can cuff design may reduce complications but meticulous pressure monitoring is an cuffed tube with control of cuff pressure and tube movement be to cause for individual clinical in intensive care there be but in a with patients this not be a or The cuffed while from increased complexity and a of manufactured that additional physician errors may lie within the may become when with other factors are most likely to be by are in time and from the direct control high decision and a recent had a critical in which patient was compromised to pressure on the In while pediatric airway itself has not have been made to control of the airway and reduced airway through development of a pediatric Despite potential of the CTT they are to against a technique that has a and CTT also have with a smaller of and a for they have a place in pediatric anesthesia but with their increased added complexity and the problems associated with cuffed tubes in the they remains a for the older child. the of past the use of uncuffed tracheal tubes (UTT) was the for endotracheal intubation in children years of age pediatric anesthesia and in the pediatric intensive care unit In two have that UTT until in routine practice in children by some pediatric arguments were in favor of this the use of a UTT was to reduce the risk of laryngeal mucosa and the risk of secondary subglottic stenosis. the use of a cuffed tracheal tube was not because of such as a subglottic of the trachea. the of a CTT the use of a tube with a smaller internal leading to airway as well as an increased work of breathing and risk of tube these arguments were only when children anesthesia with or in the neonatal intensive care studies have that the use of CTT was safe in pediatric anesthesia as well as in leading to a use of CTT by many endotracheal intubation with a CTT many This will these and the reasons we have to use CTT in our The use of an size of is not associated with an increased risk of In a by in that evidence we have is that cuffed tubes are not more than uncuffed and many studies are available that provide evidence of the of CTT in In their in Khine compared (10) the use of CTT and UTT in pediatric One of their was the incidence of airway such as which was regarded as evidence of more in the CTT group as compared with the UTT group the In evaluated the use of CTT their in routine practice in in that complications in the were not associated to the use of A recent study by evaluated the use of the Khine formula in the size of CTT in pediatric secondary outcome was the incidence of postintubation reported six cases of complications cases cases using or tracheal reintubation or subglottic stenosis were and there were long-term The complications were in to the use of CTT of an evaluated the of CTT in a large of critically ill children in a The outcome was the of postextubation long-term tracheal intubation using either a CTT or difference between the two even in provided the CTT size was selected and the cuff pressure of the CTT was and even in the the use of a CTT is safe as by In the authors that the of complications tracheal intubation in children was not related to the use of a In risk factors for have been prolonged duration of intubation and severe the is the use of an oversized tracheal study has an increased risk of airway complications related to the use of CTT provided a CTT of size is and the cuff pressure is and of CTT is that the of a cuff a seal between the cuff of the CTT and the trachea. 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