Decannulation of tracheotomized patients after long-term mechanical ventilation – results of a prospective multicentric study in German neurological early rehabilitation hospitals

In a prospective multicentric registry study, the medical routine data of n = 831 consecutive tracheotomized ERC patients were collected. A patient consent was not required, because only routine medical data were collected and evaluated anonymously and no interventions were performed. The routine data were documented at the participating clinics without personal data (name, place of residence, etc.). The recruiting was carried out between 09/2014 and 03/2016 at five ERCs in the Berlin/Brandenburg area. Inclusion criteria were a tracheotomy due to invasive mechanical long-term ventilation and a successful weaning from mechanical ventilation in the ICU or ERC.

We collected sociodemographic data (age, sex), medical data (type of critical illness, neurological, cardiac, pulmonary, renal, gastrointestinal, oncological, orthopedic and psychiatric comorbidities, respiratory parameters, tracheotomy technique), functional assessments (Early Rehabilitation Barthel Index, Bogenhausener Dysphagia Score, Coma Recovery Scale-Revised), and complications during the decannulation and rehabilitation periods (pneumonia, sepsis, laryngeal edema, tracheal stenosis, tracheomalacia). The primary endpoint was the decannulation status at discharge from the ERC (decannulated vs. nondecannulated). A decannulation was being assessed as successful if no respiratory complications occurred during the patient‘s stay in the ERC (or at least 2 weeks after decannulation). A standardized procedure for tracheal cannula management [6] was not available for all five participating clinics.

While age in other studies [5, 7] had an effect on decannulation (younger patients had a higher probability of decannulation than older ones), the negative association with the male sex was rather unexpected. For example, a recent review of sex differences after stroke [8] shows a better functional outcome for male patients, as does a recent study [9] in geriatric patients after stroke (n = 919, 56% male), from which at least 55% of our patients suffered. However, nearly 70% of all patients in our study were male, which could have led to a bias.

Heart diseases also had an effect, whereby patients had a higher decannulation rate when cardiac disease was acute compared to chronic. One possible explanation for this could be the high prevalence of cognitive impairments that have an influence on voluntary secretion management and food intake (e.g., in terms of attentional focus or executive planning). For example, 50% of the patients experienced postoperative delirium after bypass surgery [10] and 25–74% of the chronic cardiac patients were cognitively impaired [11].

Patients with a dilatational tracheotomy had a 66% higher probability of decannulation than patients with a surgical tracheotomy. Numerous studies support our finding by showing a lower complication rate (e.g. fewer postoperative infections or less peristomal bleeding) for dilatational tracheotomy [12‐15]. In addition, long-term complications such as tracheal stenosis are also less frequent after dilatational tracheotomy [16, 17]. On which basis the specific tracheotomy technique was chosen in the ICU cannot be assessed. Our data show a clear superiority of the dilatation tracheotomy with respect to decannulation.

A high predictive value for decannulation had complications during the rehabilitation period. These included pneumonia and respiratory infections, which in tracheotomized patients can be caused by aspiration [18], and bacterial colonization after tracheotomy [19], but also by the TC itself [20]. Other complications, such as laryngeal edema, tracheomalacia, or tracheal stenosis, were astonishingly rare in the patients observed here compared to other studies [21], but did have an effect on decannulation.

In other studies, the duration of mechanical ventilation also had a negative effect on decannulation and on the patient‘s functional status at discharge [22]. With regard to weaning from the TC, we assume above all a negative influence on swallowing functions. Even a prolonged endotracheal intubation (≥ 48 h) is an independent predictor of dysphagia [23, 24] and leads to severe and persistent dysphagia with aspiration, independently of the underlying critical illness [25]. Also, the cuffed TC itself has a negative impact on deglutition: Above all, the absence of a physiological airflow through larynx, pharynx, nose and mouth is problematic because it is an important stimulus for spontaneous swallowing. Furthermore, the TC leads to a ubiquitous sensory impairment due to a lack of stimulation of chemo- and pressure receptors in the laryngeal mucosa. The longer the physiological airflow is interrupted by invasive mechanical ventilation, the more seriously deglutition processes can be impaired, which in turn requires a cuffed TC to protect the lower airways from aspiration [26]. Decannulation is therefore highly dependent on the extent to which swallowing functions (through physiological airflow control and dysphagia therapy) are improved.

The type of feeding at admission to the ERC (through nasogastric tube, PEG or orally) had a significant influence on decannulation. Patients who had already had a PEG at admission could not be decannulated to a large extent compared to patients who took an oral diet. In this connection, the type of diet reflects the severity of swallowing. Dysphagia may be the result of neurological damage in areas relevant for swallowing or of the cuffed TC itself [27]. Since all invasively mechanically ventilated patients are at high risk for the development of dysphagia with aspiration, an exhaustive instrument-based or clinical swallowing test should be performed prior to oral feeding [26]; however, the decision criteria for the onset of an oral diet in the ICU were not collected, so that it cannot be ruled out that among the patients with oral diet at admission to the ERC were some with severe dysphagia.

A further predictor was the level of alertness / responsivity at admission to the ERC, which was assessed by CRS-R [28]. Decannulated patients had a significantly higher scale value at admission than nondecannulated patients. Presumably, alertness has a direct impact on other functions, such as safe food intake or effective secretion management. In patients with traumatic brain injury (n = 20, 80% male, age group 21–85), a close relationship was found between the level of consciousness and the probability of decannulation. A reduced awareness was associated with dysphagia, aspiration and pneumonia [27]. However, a significant influence could not be shown in all studies [3]. Moreover, “alertness” is difficult to operationalize. In assessments such as the CRS-R, parameters like attention or object recognition are quantified quantitatively by means of verbal and motor responses, which can be limited by peripheral or central paresis, disorientation, delirium or reduced instructional comprehension in critically ill patients. It is possible that the CRS-R parameter is an indicator of the severity of the cerebral disease per se, which limits consciousness and all levels of function.

CIP and CIM are frequent complications in critically ill patients and affect the motor and sensory axons of the peripheral nervous system. An important risk factor is sepsis [29], which occurred in 37.7% of the patients examined here. A current electrophysiological study [30] on the frequency of CIP / CIM in early rehabilitation patients (n = 782) was able to demonstrate it in almost 70% of cases; the ventilation duration was significantly increased (p < 0.001), with an average of 32.1 days vs. 20.6 days in patients without CIP / CIM. In accordance with that, in our study patients with CIP / CIM could be decannulated significantly less frequently than patients without. The severity of the CIP / CIM may also have had an influence (e.g., on coughing and swallowing), but this has not been assessed.

Our study has limitations. Thus, the severity of the neurological and other critical illnesses and comorbidities which could have an effect on decannulation with regard to the resulting dysphagia was not assessed [31]. Also, parameters from the ICU (e.g., ventilation pressure or criteria for the tracheotomy technique used or the start of oral diet) were not available, so that their influence on decannulation could not be determined. In addition, some variables that had an influence on the decannulation in other studies or were difficult to objectify were not assessed, such as recurrent vomiting [7], the effectiveness of coughing, tracheal secretion or the therapeutic approach for decannulation. Also, parameters that reflect motor function (strength, mobilization, ability to sit up, etc.) that are important for swallowing were not collected, as motor scores were not a part of the routine procedure at four of the five participating clinics. Since no follow-up was carried out after the patients were discharged from the ERC, it is impossible to say whether patients had to be recannulated after this period. The number of recannulations required during the observation period itself was very low, affecting only 24 patients (4.9%) of whom 16 could not be decannulated.