Complications that occur during surgery are usually related to the presence of interstitial air (pneumothorax, pneumomediastinum, subcutaneous emphysema). The reported incidence ranges from 0 or close to zero1,14–18 to 28%.9 Of these, the most common one is pneumomediastinum. The most plausible explanation is the child's higher location of the pleural dome, which can sometimes reach the cervical region. Careful dissection technique, avoiding dissections performed laterally to the trachea, is the best way to avoid them. In small, asymptomatic pneumothorax and pneumomediastinum, the management is conservative. Pleural drainage may be necessary in larger ones. Subcutaneous emphysema can occur due to the closing of the edges of the postoperative wound with tight sutures or by making a very compressive dressing around the cannula. Neither measure is indicated. If it occurs, the opening of sutures and replacing the compressive dressing by a looser one are indicated.

The routine indication of chest radiography after tracheostomy has been discussed. In the literature, it seems that some services always require radiography.10,13,19 In asymptomatic and non-preterm patients, however, the current trend is that of non-indication,16 as there is a progressive decrease in the complications described in the previous paragraph.14,15 Moreover, except when symptomatic, such complications do not require an intervention. It should be noted that cases of late pneumothorax, associated with the closure of tracheocutaneous fistula, have been described,2 in addition to those well known to be associated to mechanical ventilation with inadequate parameters.

Excessive bleeding during the surgical procedure may be due to injury to large cervical vessels or anomalous vessels, in addition to injuries to the thyroid gland and eventually the innominate artery. Again, the best prophylaxis is a careful dissection and the treatment is the ligation or cauterization of the vessel or bleeding point, respectively. Bleeding was ranked as the 3rd most frequent intraoperative complication in two studies, after pneumomediastinum and pneumothorax, in that order (in one study it occurred in 5% of children under 1year and in 7% of older ones, and in the other, in 1.6% of cases).9,13 A study reporting 37 years of experience in a Turkish service reported a 0.7% rate of intraoperative bleeding in 282 tracheostomies.21 A Brazilian study and an Indian study found no cases of transoperative bleeding.17,18

Injury to recurrent nerves due to lateral dissections in the trachea, esophageal puncture due to poor cannula placement, cricoid incision in the case of very high tracheostomies and the false passage due to inadequate cannula insertion and positioning may all result from poor surgical technique and are not common. A North American series depicts this low frequency, finding an incidence of 0.8% of tracheoesophageal fistula.13 A Portuguese study reporting a 25year experience with tracheostomy evaluated 27 patients and found a case of transoperative tracheoesophageal fistula (3.7%).21 The false passage is not so uncommon and can occur in 7% of preterm babies22 and in 0.8%13 to 16% of older children.23 It can also occur in the postoperative period, after accidental decannulation and an inaccurate attempt to reposition the cannula, usually by family members and even health professionals who are not appropriately trained. It is a frequent cause of return to the hospital after discharge.24

Selective intubation usually occurs in preterm infants or even older children in the case of lower neck tracheostomies, where cannulas with adequate diameters, but very long, are chosen.

Finally, cardiorespiratory arrest during tracheostomy is extremely rare, described at a frequency of 0.8%.13

Bleeding in the immediate postoperative period of the stoma construction has a relatively low prevalence, ranging from 1.8%19 to 5.2% of children.25 In general, it is the result of inadequate hemostasis during the procedure and can be significant for a neonate. Surgical revision may be necessary.19

Accidental primary decannulation is a severe complication and its incidence ranges from 0.8%13 and 0.9%26 to 20%15,27 in the literature. In the series of 25 tracheostomized patients in Barcelona, ​​20% had accidental decannulation, all in the first 48h (80% in the first 24h). Cardiorespiratory arrest occurred in 80% of patients who underwent decannulation, with death occurring in one.27 In a Scottish series, cannula displacement occurred in 5.2% of cases in the early postoperative period.25 A Brazilian series showed an accidental decannulation rate of 2.44%.17 Another series, reporting 30 years of experience with pediatric tracheostomy at a university hospital in Zurich, found a 13% cannula displacement rate that occurred 48h after the procedure, but without discriminating at what moment it occurred, making it difficult to classify it as an early or late postoperative occurrence.14 As the consequences of decannulation can be dramatic, a good practice is to use containment sutures on the anterior tracheal wall that exit the stoma or, according to the most current trend, to mature the stoma,18 especially in neonates and small infants, facilitating the quick and correct repositioning of the cannula in case of displacement. Another practice, less often used, is to make one or two anchoring stitches from the plastic cannula to the skin.

While cannula obstruction by a blood clot is usually an early postoperative complication, the one caused by a mucus plug is generally a later one. However, in cases with underlying disease with alterations in the quantity and quality of the secretion, especially in preterm infants, the plug may also occur early. Early cannula obstruction occurred in 4% of tracheostomized patients in a pediatric ICU27 and in 4.6% of patients up to the 4th postoperative day in a study that sought to evaluate the safety of cannula replacement on the 3rd day after tracheostomy, with no fatal cases.28 A Korean article, describing a tracheostomy technique with a vertical tracheal incision and stoma maturation, reported a cannula obstruction rate of 0.9%, with none leading to the patient's death,26 as in an Indian study that also used the stoma maturation technique, but using a circular tracheal incision.18 The continuous administration of humidified air until the first cannula change can reduce this type of complication. Another cause of cannula obstruction, the false passage, has been described in 3.6% of cases in a Brazilian sample.17

The local infection (cellulitis), which occurs in the earliest stages, manifests as hyperemia of the peristomal skin, and hardening and increased local heat may occur. There may be greater or lesser amounts of secretion. Infection was found in 1.6%–14.6% of tracheostomized children.17,19,28,29 Treatment includes cannula replacement - traditionally recommended up to a maximum of 5–7 days, and can be safely removed on the 3rd day,28 local hygiene, use of antibiotic ointments and, sometimes, oral antibiotic therapy with spectrum for the most common respiratory microorganisms. Cautery overuse in the dissection of subcutaneous tissue and infrahyoid muscles, with excessive tissue destruction, is listed as one of the potential causes.19 The appearance of skin lesions such as irritation of the peri-tracheostoma skin and pressure ulcers can be minimized with the use of waterproof dressings with or without antimicrobial properties, as well as the use of Velcro fasteners instead of cotton laces, since the first ones tend to accumulate less moisture and secretion.30

Excessive air leakage around the tracheostomy cannula is another early complication of tracheostomy and can be a problem in a tracheostomized patient who requires respiratory support with high ventilatory parameters. It can occur in up to 14.6% of preterm newborns, especially those with very low birth weight (< 1kg).19 It can also occur in infants, as demonstrated by Carr et al. in their series, with an incidence of 7% of patients before the first cannula change.15

Decannulation was the most frequent late complication of tracheostomy (6%) in a Canadian cohort with 30 years of follow-up. It was the cause of death in 2% of these children.31 A similar incidence of late decannulation was found in a Korean study (2.7%),26 which resulted in the death of one patient at home. In a Brazilian series evaluating 58 children, decannulation occurred in 3 (5.7%) patients, one of which had cardiopulmonary arrest that was reversed, whereas the other died.32 In another Brazilian series, the incidence was the same, occurring in 5.7%, with no fatal cases.17 An Indian study found no cases of accidental decannulation.18

Obstruction by a mucus plug occurred in 10% of patients in a study carried out in Calgary, Canada.33 All had cardiorespiratory arrest and there was one death. All obstructions occurred between 7 and 90 days after the tracheostomy. A lower incidence was observed in a Brazilian series (4.1% of patients),17 and in a Korean series (only 1 case — 0.9%).26 Not only the mucous plug, but also granulomas and false passage can lead to cannula obstruction. This complication can be prevented with correct care of the tracheostomy cannula since the first postoperative days, involving aspirations and periodic cannula changes. Frequent aspirations, and the instillation of saline solution to help in the humidification of mucus can also be performed, are essential to avoid obstruction by dry secretion in the cannula lumen.34

Local and low respiratory infections were the most frequent complications in some studies,15 affecting up to 90% of patients.33 Perhaps part of this increased incidence of infection is due to the non-differentiation between colonization and infection. Long-term tracheostomized children may become colonized by S. aureus, including those resistant to methicillin, and / or P. aeruginosa and other Gram-negative microorganisms.35 It is necessary to differentiate between these two conditions. Colonization does not require treatment, unless there is a sign of acute infection or before reconstructive airway procedures. Surgical wound infection can occur in any surgical procedure and should be treated with a short course of oral antibiotics. The International Pediatric Otolaryngology Group in its 2016 consensus recommends the use of routine antimicrobial prophylaxis at least until the first cannula change. Tracheitis can be an early or late complication. It occurred late in 48.8% of 156 cases.36 In the case of tracheitis, routine cultures of the prosthesis or tracheal secretions is not recommended.37 In cases of lower airway infections (bacterial bronchitis and pneumonia), the method of choice for collecting secretions for bacterial culture is the bronchoalveolar lavage, preferably the “protected” type, carried out by a catheter that goes through the biopsy channel of the bronchoscope, preventing contamination by secretions from the upper airways.38

Suprastomal collapse, subglottic stenosis and tracheal stenosis have similar mechanisms, resulting from damage to the mucosa and tracheal cartilage, and can progress with partial absorption of cartilage, fibrosis and scar stenosis. The suprastomal collapse results from the weakening of the anterior tracheal wall, which is generally superior to the tracheostoma, and can be prevented by fixing the tracheal wall to the tracheostoma skin at the time of the surgery. Its occurrence varied between 0.2% and 13.1% in two Brazilian studies.1,29 Subglottic stenosis is usually secondary to an inadvertent injury to the cricoid cartilage during the procedure or injuries induced by previous intubation. A Brazilian study reported the highest incidence of subglottic stenosis found in the literature, 27.4%, associated with tracheostomy.39 Tracheal stenosis, on the other hand, can occur above, at the site or below the tracheostoma, as far as the tip of the cannula reaches the tracheal wall, including the carina region. It can also be secondary to tracheal injuries resulting from previous intubation or even the repeated aspirations with catheters performed using an inadequate technique. The incidence of tracheal stenosis after tracheostomy ranged from 0.4%3 to 12% of cases.9

The tracheocutaneous fistula (TCF), that is, the epithelialization of the trajectory from the skin to the trachea (mature stoma), is desirable in the early postoperative period, but it can become a long-term problem, preventing the spontaneous closure of the tracheostoma. Most tracheostomas close spontaneously through healing by secondary intention. The incidence of TCF in the series varies between 3.1% and 57.3%.1,40,41 A study that reviewed the 14-year experience of pediatric tracheostomy in a hospital in Liverpool showed a percentage of 11.9% of need for surgical closure of the TCF. These were children with long-term tracheostomies (at least two years, with a median of 4 years) who had undergone the surgical procedure before 1year of age.42 This hypothesis was also corroborated by a North-American study, which demonstrated a significantly increased relative risk of developing tracheocutaneous fistula in patients who remained tracheostomized for more than 24 months.42 Currently, there is a tendency among surgeons to mature the stoma early. There is a concern that this surgical approach will increase the TCF rate, mainly because with the use of some techniques in which maturation was universal, such as “starplasty”, this occurs in practically 100% of cases.43 However, this assertion has not been confirmed in an Israeli service experience.44 Moreover, one of the first comparative studies showed similar incidences between matured and unmatured stomas, 10.2% and 12.8%, respectively. Also, there was not a higher incidence of granulation tissue formation in the mature stoma.45 Another study that compared the overall complications of tracheostomy between matured and non-matured stomas also found no statistically significant differences, including TCF.36 More recently, using a simple technique without the construction of flaps, with only two sutures in the inferior-lateral region of the stoma joining the subcutaneous tissue with the pretracheal fascia, the TCF rate in matured and non-matured stomas was similar (27% vs. 22%, respectively).46

A tracheo-vascular fistula with the innominate artery is a rare complication,2,15 described in articles that show successful surgical repair techniques. The innominate artery injury that can occur during the transoperative period in very low tracheostomies (below the 4th tracheal ring) is even rarer and is caused by direct trauma to the artery, especially in cases of arteries located at a higher position in the neck. This bleeding should not be mistaken for recurrent bleeding, of different intensities, where the tracheostomy cannula can cause local irritation and late hemorrhage and inflammation, with bleeding secondary to the presence of granulomas, especially in the case of tracheal aspirations performed with less delicate care. The true innominate artery fistula is usually a late event (many cases are reported in the 3rd week after the tracheostomy) and may occur when the tip of a poorly positioned tracheostomy cannula (mainly metallic ones) causes friction and results in erosion and ulceration on the anterior tracheal wall and on the posterior wall of the innominate artery. Precipitating factors comprise the use of cannulas that have cuffs with excessive pressure, low tracheal incision and hyperextension of the neck. Its incidence is low, less than 1%, as demonstrated in a large Spanish multicenter cohort, in which there was only one case (0.4%).3 It must be recognized quickly as it requires emergency surgical intervention. In some cases, more temporary “sentinel” bleeds can indicate a devastating hemorrhage. A clinical team trained to stabilize the patient for emergency surgery is important in the acute phase. When unrecognized, inadequately stabilized prior to surgery and untreated surgically as an emergency case, the innominate artery fistula is associated with death in practically 100% of affected cases. However, when adequately managed in a timely manner, it can have a more favorable outcome, as demonstrated by a recent systematic review that found 38.6% of mortality in the described cases.47

The late tracheoesophageal fistula is a rare occurrence, with an incidence of less than 1%. It occurs due to the necrosis of the posterior tracheal wall, usually secondary to the use of poorly positioned cannulas with cuffs or metallic ones. There are more reports in the literature mentioning it as a tracheostomy complication in adults. In a study that analyzed the efficacy of sliding tracheoplasty in the repair of tracheoesophageal fistulas, one of 9 cases of operated fistulas was secondary to complications caused by the tracheostomy cannula.48

It is a debatable topic in the literature whether tracheal granulation or granuloma represents an actual complication of tracheostomy, as it is often asymptomatic.1 It has an estimated frequency of 12.3% to 66% of cases.33 It was the main late complication of tracheostomy in at least two studies, published in 1993 and 2018.5,29 The recent series that studied ventilator-dependent institutionalized cases showed the presence of peristomal granulomas in 40.6% and suprastomal in 37.5% of children. Taking into account the low incidence of large and obstructive granulomas and the failure of the surgical excision to decrease their recurrence, it was concluded that excision was not recommended in children with non-obstructive granulomas with stable tracheostomies.49 However, when considering decannulating the patient, a previous endoscopy and excision of granulomas that may hinder the process is mandatory. Management can be endoscopic, using different instruments, or transtracheostoma. In the case of granulomas that are too large or firm (mature) to be removed through endoscopic techniques, or too large or firm to be removed via the stoma, open excision is indicated.

Death is a potential undesirable event in tracheostomized patients. Most of the time, it is not correlated with the procedure itself, but occurs secondary to the evolution of the underlying disease. The overall mortality rate varies between case series, and reach up to 40%, while mortality from the procedure itself can reach up to 6% in the pediatric population.7,9,13 Children with heart and neurological problems have a higher overall mortality rate when compared to children with craniofacial malformations or upper respiratory obstruction.9 Preterm children and extremely low-birth-weight infants also have higher mortality rates.50 A recent study showed that children under 1year of age have a seven-fold higher risk of death when compared to children over 1year.12 Morbidity and mortality rates significantly depend on how well trained the medical staff is and how well informed are the patients’ parents and caregivers, since the main causes of death are accidental decannulation and stoma blockage by secretion plug.1 Low rates of complications and death are also correlated to the elective procedure, in referral hospitals and by experienced, well-trained surgeons.19