The current better standard of care in the intensive care unit (ICU) has allowed a higher proportion of patients with critical illnesses to survive, meaning that a growing number of patients depend on prolonged critical care and are known as chronically critical patients. One of the characteristics of this group of patients is the need for tracheostomy (TO), either because they require long-term mechanical ventilation or because they have an unprotected airway.1 This specific group of patients requires long-term rehabilitation and medical care in specialized centers (Weaning and Rehabilitation Centers).
TO for ventilation purposes has become standard procedure in ICUs,2–7 and is performed in ∼10% of all patients requiring invasive mechanical ventilation (iMV),8 rising to 34% in those who will require iMV for >48 hours.9
The TO cannula bears the risk of inducing late complications such as granulomas, stenosis, excessive central airway collapse, and fistulae of the innominate artery, among others. Early on, these complications may be subclinical, but some may progress and have a clinical impact, affecting the normal ventilation of the patient or hindering weaning or decannulation.10
Such complications are not always related to the TO cannula, as they might also be a progression of lesions caused by the orotracheal tube (OTT), or as a consequence of the period of hypoperfusion during shock, compression, and ischemia caused by the orotracheal cuff, gastroesophageal reflux disease, etc.
The aim of this study was to describe the prevalence and characteristics of tracheal lesions in the flexible bronchoscopies of tracheostomized patients admitted to a weaning and rehabilitation center, and to analyze the factors associated with severe lesions (>50% obstruction of the tracheal lumen).
MATERIALS AND METHODS
This analytical, observational, and transversal study was conducted at the Clínica Basilea, a weaning and rehabilitation center in the City of Buenos Aires, Argentina. Flexible bronchoscopy reports were retrieved from the database of our tracheostomized patients between March 2006 and February 2017. The review of all bronchoscopies was performed by a pulmonologist with >30 years of experience in the field.
The study only reviewed the first flexible bronchoscopy performed at some point in time within the first 10 days of admission at the weaning and rehabilitation center. All assessments were performed via a nasal approach, and, once the bronchoscope was placed over the vocal chords, the TO cannula was removed and the scope was then advanced toward the tracheobronchial tree. The airway was first explored under relaxed breathing and then during voluntary or stimulated cough. The tracheal lesions were classified according to their severity as follows: severe, above 50% obstruction, or mild, if the obstruction was <50%.11 Lesions were classified on the basis of location as glottic, subglottic, at the level of the ostomy, tracheal or bronchial, and according to their type as granuloma, stenosis, or excessive central airway collapse (considering the dynamic collapse within the lesion). Possible predictors of severe lesions were analyzed: age, sex, days of OTT intubation/TO, albumin level on day 1 of hospitalization at the Weaning and Rehabilitation Center, and diagnosis at the time of ICU admission.
The continuous variables followed a normal distribution and were expressed in mean values and SDs; if this condition was not met, the study reported the median and the first and the third quartiles. The categorical variables were reported in absolute numbers and percentages. Either the Student or the Mann-Whitney U tests were used to compare the continuous variables, and the χ2 or the Fischer exact test to compare proportions, as needed. All P-values below 0.05 were considered significant. The IBM SPSS Macintosh software was used for the analysis.
This study was carried out in compliance with the amended Helsinki Declaration, and a written informed consent was signed by all patients, allowing us to publish the data.
A total of 414 tracheostomized patients admitted to our weaning and rehabilitation center who had been explored with a flexible bronchoscopy in our center were reviewed. An overall 53% of the patients were male individuals, and the mean age was 65 years (±16.2). A total of 121 (29%) of the patients assessed had normal findings, 202 (49%) showed mild lesions with <50% luminal obstruction, and 91 (22%) had tracheal obstructions exceeding 50%.
The list of diagnoses at the time of ICU admission is shown in Table 1.
Granulomas were found in 230 patients (55%), 32 of such granulomas (26%) were severe, mainly located in the subglottic region (93.75%). Of the 27 patients with stenosis, 17 (63%) were severe. Excessive central airway collapse was found in 120 patients (31.8%), with severe collapse in 65 (54%), as shown in Table 2 and Figure 1.
Statistically significant differences were found in the age of the group that developed severe lesions when compared with the other one. The group that developed severe lesions was older [mean age, 73 y (Q1 to Q3), 58.7 to 81] than the group of patients who did not develop any lesion at all [mean age, 69 y (Q1 to Q3), 55.7 to 75; P=0.001]. Moreover, the number of days with an artificial airway showed to be a significant variable [mean, 84.5 d (Q1 to Q3), 49 to 135.5 d] in this group with complications compared with a mean of 59.5 days in the other one (Q1 to Q3, 42 to 98; P=0.035).
The follow-up of the patients with severe lesions showed that 74% could be successfully weaned, and decannulation was achieved in 31%. Of the 91 patients with severe conditions, 58% were successfully weaned, or had been admitted at our center already weaned from iMV (53/91), and 29% (26/91) could be decannulated. Of this latter group, 8 required a surgical intervention and/or an endoscopy to improve their condition (4 granulomas, 4 stenoses, and 12 excessive central airway collapse; some of the patients had >1 lesion that required intervention).
The most prevalent lesions in our population of tracheostomized patients were granulomas, and this finding was consistent with other published series.10,12 Furthermore, and also in accordance with the literature, most of these lesions were classified as mild, as they occluded <50% of the tracheal lumen, allowing successful decannulation in fit patients.11 However, if there is a presence of granulation tissue close to the lower end of the TO cannula,13 it can block normal ventilation and complicate the weaning process, or create asynchronies with the ventilator.
Severe excessive central airway collapse, including dynamic collapse, was the second most frequent lesion found. This type may be overlooked by computed tomographic scans, as these images do not assess airways from a functional standpoint. The prevalence of excessive central airway collapse–type lesions was 29%, consistent with Law’s description.12
Stenotic type tracheal lesions had a low prevalence, between 3% and 12%, as shown by Law et al12 and Streitz and Shapshay.14 Most of the stenoses in our study were considered as severe lesions, and age was one of the factors associated with their development, consistent with Epstein’s publication.10
Contrary to Rumbak’s findings,11 which describe a prevalence of severe lesions around 10% in their cases, our prevalence is somewhat higher. This might be explained by the fact that every single patient admitted at our center was included, whether they were dependent on iMV, whether they were patients about to be weaned, or none of the above, whereas Rumbak only included patients who had been weaned from MV and those who were ready to start the process of their cuff being deflated and their TO cannula being closed.
These lesions are frequently undiagnosed in the ICU setting during the acute phase, particularly when the lesions are in the subclinical stage. In addition, some patients may die without a diagnosis, rendering a flawed prevalence rate. If, in contrast, the bronchoscopy is performed routinely at the time of hospitalization, as proposed in our study, the diagnosis is accurate even though the lesion might not have any clinical impact. Although we used different criteria to perform the examination, our results agree with descriptions in the literature.15–17
Consistent with what Whited18 published, we found a similar association between the presence of tracheal lesions and the duration for which our patients required an artificial airway, although the former author based his study on different lengths of time using the OTT.
The follow-up of our patients with severe lesions shows that over half of them can be weaned from the iMV. The weaning of the iMV can be achieved in patients with tracheal lesions above the cannula or in those who, although the lesion is below the TO cannula, their TO can be overlooked, thus allowing the normal flow of the air. However, 42% of patients could not be weaned due to different factors unrelated to the lesions, such as patients with amyotrophic lateral sclerosis.
Some patients could not be weaned and remained iMV-dependent or had swallowing disorders. In contrast, others did not require intervention for decannulation, because their lesions, which were close to 50% luminal obstruction, improved with the passing of time.
One of the limitations of our study is the inability to relate airway lesions with the TO technique (open vs. percutaneous dilatation), as, in the referral discharge report from other centers, it was seldom described and thus could not be included in the analysis.
The correlation between tracheal lesions and medical data before hospitalization, such as cuff pressure or patient’s factors predicting poor wound healing, could not be assessed, as we did not have the ICU data, and the examination with the bronchoscope was carried out at our center at the time of hospitalization.
The use of flexible bronchoscopy for the diagnosis and assessment of severe lesions might be another likely limitation. Although there are alternative methods for assessment (x-rays, computed tomography, and magnetic resonance imaging), flexible bronchoscopy is widely described in the literature as a very good method to diagnose and assess severity.10,12,14,16,18
The prevalence of tracheal lesions in our center is within the expected rate for this type of patients. Early identification allows making management decisions to avoid complications during recovery. We were able to identify age and duration with an artificial airway as the factors related to the development of severe lesions.
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