In this single-center, retrospective observational study we analyzed the modalities of airway management in 151 critically ill, mechanically ventilated patients with COVID-19, admitted to the ICUs of one of the largest hospitals in Italy, during the first SARS-CoV-2 pandemic wave. In addition, we focused our attention on patients that were diagnosed with tracheomalacia during their ICU length of stay.
A major finding of our study is that a tracheostomy was performed in almost 50% of patients treated with invasive mechanical ventilation for COVID-19 related respiratory failure and that in our cohort of patients, the incidence of tracheostomy was not different according to ARDS severity. These findings differ markedly from what has been described in the “classic” ARDS population. Indeed, a recent worldwide observational study evaluating the incidence and characteristics of ARDS patients in the ICU, described that a tracheostomy was performed in 13% of the overall ARDS population , increasing from 9.6% in mild to 14.5% in severe ARDS patients . On the contrary, recent literature regarding COVID-induced ARDS already described an increased use of tracheostomy, in line with our findings, ranging from 32% up to 60% [13–16].
The major contributing factor to this high incidence of tracheostomies might be the fact that patients with COVID-induced ARDS seem to require more time to improve, as compared to “classic” ARDS . Indeed, in our population, the median ICU length of stay was 14 (9–27) days, which is longer as compared to the 10 (5–20) of the LUNG SAFE . The reasons for this longer ICU length of stay have not been fully understood. It is conceivable that several aspects related to COVID’s pathophysiology, such as the marked vascular and endothelial involvement , a high rate of secondary bacterial infections , and a high incidence of barotrauma [16–19], contribute to the longer course of the disease. Indeed, a high rate of bacterial infections is reported also in our cohort of patients, more frequently in tracheostomized patients with a longer duration of stay.
Another aspect that deserves discussion is the high percentage of surgical tracheostomies in our cohort. Italy has been the first European country hit by the 2020 pandemic. In spring 2020, the knowledge about the novel beta-coronavirus was extremely scarce and no data were available about the safety of healthcare professionals performing tracheostomies in infected patients. Performing a tracheostomy is certainly a procedure at very high risk for infection. In addition, the generation of aerosol particles, potentially containing the virus, is certainly favored in critically ill patients by the necessity to use high positive intrathoracic pressures. The idea that a surgical approach would be safer for the operator and the fact that surgeons were relatively free, due to the suspension of elective surgery, explain our finding. There is no evidence to recommend one method over the others and the daily availability of experienced surgical team avoided delays. Moreover, percutaneous tracheostomy involves more extensive manipulation of the airway with increased aerosolization risk . In addition, it is certainly true that a surgical tracheostomy guarantees an easier cannula repositioning in case of accidental removal. This aspect might be of particular importance in the context of a pandemic surge, characterized by the presence of inexperienced doctors and nurses in the ICU. Of note, several studies described that the surgical technique was not associated with higher complication rates [21–23].
In our study, we compared the characteristics of patients in whom a tracheostomy was performed with those ventilated exclusively via an endotracheal tube (Table 1). The major difference was a longer disease course in tracheostomized patients, as demonstrated by a longer duration of mechanical ventilation and longer ICU and hospital length of stay. Tracheostomized patients developed bacterial infections more often. No difference in mortality was observed in the two groups. Of course, our data are purely descriptive and no conclusions on the effect of tracheostomy on COVID-ARDS can be drawn.
Other authors investigated the use of tracheostomy in SARS-CoV-2 patients, describing the overall safety of the procedure [22, 24–32]. Several studies reported a longer ICU length of stay in tracheostomized patients [25, 33].
The cohort of the Queen Elizabeth Hospital in Birmingham , is the only one describing a higher 30-day survival in patients undergoing tracheostomy as compared to patients that did not. While the authors accounted for disease severity in their analysis, it is important to underline the observational, non-randomized nature of the study.
Finally, in the present study, we focused our attention on tracheomalacia. Several factors are considered a risk for the development of tracheomalacia. In the general adult population, the most important one seems to be chronic inflammation, in the context of chronic obstructive pulmonary disease . On the other hand, despite less evidence, trauma, infections, prolonged intubation, and tracheostomy have been considered potential risk factors [34–37].
In our cohort, in 8 of 151 patients (5%), tracheomalacia was suspected clinically and confirmed with a fiberoptic evaluation. To the best of our knowledge, this is the largest report of tracheomalacia in COVID patients. A single case of tracheomegaly, with clinical features similar to our patients, was recently described .
The observed 5% percentage is higher as compared to the scarce literature, only referring to non-COVID patients. Karimpour and colleagues  describe that 0.6% out of 184 patients who underwent percutaneous Ciaglia tracheostomy in the ICU developed tracheomalacia, while Kandaswamy et al. describe an incidence of 0.7% in a case-control study including 576 mechanically ventilated patients, regardless of the presence of a tracheostomy . Several factors could explain the observed higher incidence. On the one hand, a vascular and endothelial involvement in patients with COVID-19 has been described , particularly in the lungs. To the best of our knowledge the microvascular involvement of the upper airways has not been documented so far, however, from a surgical perspective, we observed a macroscopic impairment of the vascularization of tracheal and peri-tracheal tissues.
Another factor potentially implied with the pathogenesis of tracheomalacia in this particular pandemic context is an excessive cuff pressure of the endotracheal/tracheostomy tube  leading to tracheal wall suffering. Usually, great attention is paid to this aspect by the nursing staff. However, on the one hand, the presence of inexperienced nurses, recruited from regular wards due to the extremely high number of patients in need, and on the other hand, the fear of infection due to cuff leakage and viral spread could have resulted in overall higher cuff pressures. Finally, it is conceivable to hypothesize a role of mechanical trauma of the tracheostomy tube on the tracheal wall during pronation.
In our cohort, patients diagnosed with tracheomalacia had a significantly longer clinical course (ICU and hospital length of stay) a higher rate of bacterial infections, but a similar mortality. In addition, we observed that patients diagnosed with tracheomalacia had a higher body mass index, were more frequently female and that the use of tracheostomy was higher.
On the one hand, the physiologic gender-related differences in connective tissue [42, 43] could maybe explain the observed higher incidence in females. On the other hand, the higher body mass index, already identified as a potential risk factor , could be explained by the proinflammatory effect of obesity [44, 45] and a more difficult surgical or percutaneous access to the trachea during the performance of the tracheostomy. Moreover, obesity and obstructive sleep apneas might favor the development of tracheomalacia as a result of periodic markedly negative intrathoracic pressures generated during episodes of obstruction . Of course, this would imply that at least a mild form of tracheomalacia was already present before the COVID infection and was somehow exacerbated during the critical illness.
Finally, the higher incidence of infections and the longer course of antibiotic therapy in the group of patients with tracheostomy and with tracheomalacia should be commented on. Certainly, the longer duration of ICU stay could simply have increased the probability of developing new bacterial infections, but the impact of repetitive infective events and the consequent systemic inflammation might have contributed to the pathophysiology of tracheomalacia.
The management of acquired tracheomalacia associated with mechanical ventilation is difficult and requires a multidisciplinary approach, involving critical care physicians, anesthesiologists, thoracic surgeons, and respiratory therapists. The approach might be surgical [34, 37, 48], endoscopic stent placement [34, 37, 49] or conservative management with cycles of positive pressure ventilation [34, 40]. In our cohort of patients, a conservative approach, based on spontaneous breathing cycles and positive pressure after decannulation, was successful in patients with isolated tracheomalacia, i.e., in patients that had not developed a tracheoesophageal fistula.