Indications
Both the indications of tracheostomy and characteristics of children with tracheostomy have profoundly changed in the last 50 years reflecting the changes that took place in the managment of children in a delicate condition. Until half of the 20th century and before the introduction of generalized vaccination - haemophilus influenza and corynebacterium diphtheriae - viral infections and acute bacteriophage infections, the diphtheria, and epiglottitis, were the main causes of airway complication leading to the first practices of pediatric tracheostomy. At the end of the 1900’s an increase in the use of endotracheal intubation and respiratory support for premature infants had led to a higher rate  of premature babies with the need of mechanical ventilation and associated upper airway abnormalities. (3-4)
This is how vaccination programs, better intubation procedures and the development of new technologies in intensive care have diminished emergency tracheotomy and, far from diminishing its incidence, this situation has led to the appearance of other indicators like prolonged mechanical ventilation turning tracheostomy in a programmed, long term elective procedure.(5) Most of the published studies developed in The United States and Europe consider that the most frequent causes of tracheostomy are congenital upper airway abnormalities and prolonged mechanical ventilation.(4-5)
In his review published in 2017, Watters mentioned that in a retrospective study on 917 tracheostomized children aged between 0 and 18 collected from 36 pediatric hospitals, the most frequent underlying conditions were chronic lung disease (56%), worsening of neurological function (48%) and upper airways anomalies(47%).(4) (6)
However, the situation in developing countries is probably quite different, especially in the prevalence of tracheostomy.
There is an overall increase in the prevalence of patients who need prolonged mechanical ventilation (PMV) and also in the number of children who survive with complex medical conditions for whom tracheostomy and domiciliary mechanical ventilation could be part of their treatment.
In 2008 a study that was conducted in Ricardo Gutierrez Children’s Hospital in Argentina analysed the prevalence of tracheostomy in children on mechanical ventilation support (MVS), and it was 20% during a 6-month period. It was higher than shown in other published series.(7-11)
Coinciding with previous studies, patients who underwent tracheostomy presented more length of stay and mechanical ventilation (MV) than non-tracheostomized ones. However, the mortality rate was higher in non-tracheostomized patients with more than 14 days of MV.  This could probably be because of the prolonged use of mechanical ventilation and the chronicity of this children’s situation.(12)
At this moment pediatric tracheostomy mortality rate ranks from 0.5% to 5%.(4)
In 2016, a Transference Program of mechanical ventilation chronic dependant patients or technology dependant patients was tested in the same hospital, ranging from intensive care areas to pediatric rooms. During the study, 247 patients entered the pediatric intensive care unit. Twenty four were tracheostomized. They were ventilation dependants, and clinically stable. There were 9.7% of technology dependant patients in the intensive care unit (ICU), which means the same number of beds required for severe acute patients.(13) It is because of all this that the there is a need to strengthen and implement programs, protocols and action algorithms on these patients that lead to a quick and effective dischargement whenever possible considering each particular case. Long term tracheostomy leads to a higher medical mortality rate and to a negative psychosocial impact. Because of this, decannulation is a priority when a tracheostomy is done.(14)
Up to this date, literature lacks well-established guidelines to determine the steps for decannulation. There is scarce evidence about protocols and algorithms for making decisions to support the decannulation process of the pediatric patients.
The lack of consensus for an optimal decannulation protocol may be, in part, attributed to the low amount of prospective studies centered on decannulation or the lack of studies comparing different decannulation methods.
Regarding the factors that predict success in decannulation, studies have attempted to define clinical predictors of successful decannulation. There is a consensus among authors that prior to decannulation, certain assessments must be done, and clear criteria must be established. Decannulation protocols vary widely in these reports with success rates ranging from 67% to 94%.(4)
In 2015 Knolman & Col in their review about decannulation protocols found that the studies obtained were case series or retrospective studies, with differences in the variables measured between them before decannulation. In spite of discrepancies and heterogeneity, they agreed in the different steps or goals accomplishment. Once a tracheostomy underlying indication gets corrected or solved, the patient can be considered a candidate for an eventual decannulation. A previous endoscopic assessment and progressive capping trials ensure a proper static and dynamic permeability of the airway.(15)
In 2013 Mitchell et Al published a clinical consensus about pediatric and adult tracheostomy manage. Experts agreed in that criteria must be established before a decannulation process. There was consensus in that children who underwent tracheostomy should be weaned off from mechanical support during 2 to 4 months. They should not present bronchoaspiration events and the need of tracheal secretions suction. Flexible laryngoscopy is recommended to confirm both permeability and mobility of at least one vocal cord and the elimination of any suprastomal obstructive granulation before attempting a decannulation. Children up to 2 years old must be tested capping the cannula during the day and releasing it during the night for several weeks. Other options are also mentioned, for example a sleep assessment and an exercise test. These recommendations are based on expert’s opinions and serve as solid evidence guidelines even though they are for adult patients. But there is room for further discussions and investigations regarding this topic.(16)
The role of polysomnography (PSG) in the decannulation process has been slowly increasing in acceptance even though its daily use is questionable. This is because of the financial cost it implies, the length of stay, availability of medical supplies and the need for trained physicians and health personnel. Several authors conclude that it is useful as complement of the fibronoschopy in preparing for a decannulation.(17-19)
Despite decannulation being so relevant, there are no studies in which the efficiency of the protocols has been proved.
In order to provide a better understanding on the topic in this area, a systematic review has been performed, to research the scientific evidence that is currently available, which evaluates decannulation protocols on pediatric patients.