Clinical prognostic indicators of dysphagia following prolonged orotracheal intubation in ICU patients

The clinical relevance of dysphagia after extubation is profound; it occurs frequently and affects patients across all medical and surgical diagnostic categories [1, 2]. For many hospitalized, intubated patients, underlying conditions may interact with dysphagia to produce aspiration, pneumonia, and/or respiratory compromise. Dysphagia even without aspiration can interfere with nutrition and delay clinical recovery [2].

Prolonged intubation, typically defined as longer than 48 hours [1, 3‐6], is thought to contribute to swallowing dysfunction. The development of postextubation swallowing dysfunction is well documented in the literature with high prevalence in most studies, ranging from 44 to 87% [7‐11]. However, there are relatively few studies with specific outcomes that focus on the follow-up of these patients until hospital discharge. High-quality studies are relevant to assess the influence of prolonged intubation on dysphagia and to determine which factors put patients at greater risk [11].

Longer intubation duration has been correlated to dysphagic patients [7, 12‐14] and has also been reported to be an independent predictor of dysphagia severity [15, 16]. The higher risk of dysphagia post extubation was reported in those patients with Glasgow Coma Scale scores of ≤14 [8] or age ≥55 yrs [8, 16]. In contrast, another study found that neither age nor the duration of intubation was correlated with an increase in swallowing dysfunction in post orotracheal intubation (OTI) patients [1]. Post prolonged intubation swallowing disorder extends the time to begin the oral myofunctional/swallowing assessment, to return to normal oral feeding and delays subsequent hospital discharge [14, 15, 17].

When reviewing the literature, it appears that detailed analyses on the relationship between the degree and outcome of swallowing problems and the type and degree of primary treatment are very limited. A clearer understanding of prognostic indicators has the potential to enable the rehabilitation team to better predict recovery and facilitates appropriate and cost-effective care for individuals with swallowing disorders [18, 19]. Studies have examined general prognostic indicators of swallowing function in different diseases. These indicators include: age [20, 21]; severity of the disease [22‐24]; cognitive status [18, 25]; dysphagia severity level at hospital admission and/or discharge [22, 26‐28]; presence of feeding tube [29]; time to achieve oral feeding status [14, 17, 30]; time to tracheostomy weaning [14, 31]; ventilator status [17, 25]; amount of treatment [14, 18, 26]; and length of hospital stay [12, 32].

Carefully selected process indicators should be used when evaluating the quality of the health care provided to patients with dysphagia. To enable a fair evaluation of clinical practice, process indicators should reflect expected practices in local settings, such as those found in relevant clinical guideline recommendations [19, 33]. Many of the process indicators used previously for dysphagia management evaluations are not based on sound levels of evidence, which reflects the challenge of research in this field [33]. Therefore, the purpose of our study was to determine prognostic indicators related to dysphagia at hospital discharge of intensive care unit (ICU) patients submitted to prolonged orotracheal intubation.

Of the 1,080 ICU patients who were referred to a BSE, 456 had been submitted to OTI, 85% (388) had records of prolonged OTI. Of the remaining patients, 148 met the inclusion criteria (91 males, mean age 53.51 ± 16.18; 57 females, mean age 52.88 ± 19.32). Table 4 shows the overall descriptive data.

Table 5 shows the distribution of the ASHA NOMS results on the initial swallowing assessment (DSR1) and at dysphagia resolution/hospital discharge (DSR2). As observed, most of the participants were classified as level 4 by the ASHA NOMS swallowing level scale on the initial swallowing assessment (that is individuals had moderate diet restriction and/or still required the use of a feeding tube). When looking at the distribution of participants among the different ASHA NOMS levels at the initial assessment and at dysphagia resolution/hospital discharge (DSR1 × DSR2), we can observe that 103 patients improved their swallowing to ASHA NOMS levels 5 to 7.

Table 6 shows the mean RVU obtained among the different levels on the ASHA NOMS scale at the initial assessment. The results indicate that the less severe the swallowing impairment, the lower the number of RVU.

Univariate analyses performed to identify independent variables for good treatment outcomes in patients submitted to prolonged OTI are described in Table 7. Statistically significant prognostic indicators included ASHA NOMS at initial swallowing assessment (DSR1), time to initiate oral feeding (TOF) and amount of individual treatment (RVU). Multivariate logistical regression analysis (Table 8) was performed to determine whether the association between DSR1, TOF and RVU remained after the other indicators of good prognosis had been removed. In this analysis only DSR1 remained independently associated with good treatment outcomes.

The Spearman’s rank correlation test was performed to identify possible correlations among the prognostic indicators used in our study (Table 9). This analysis indicated a moderate negative correlation between DSR1 and TOF, and a moderate positive correlation between DSR1 and RVU. A weak negative correlation was observed between DSR1 and RVU, and weak positive correlations were observed between NOI and IT, and between RVU and LS.

Recently, increased regulation has required rehabilitation programs to report their results and outline the goals of the rehabilitation process effectively and efficiently. It is essential to introduce prognostic/quality indicators in order to clearly understand and manage the quality of health care. Using prognostic/quality indicators in hospital units improves the analysis of performance over time as new procedures and technology are introduced [19]. This study represents the largest group of Brazilian patients submitted to prolonged OTI who have been assessed for possible prognostic indicators related to the swallowing functional outcome at hospital discharge.

In a large group of patients submitted to prolonged OTI, we have demonstrated that, among patients who were assessed by a BSE, the ASHA NOMS level at the initial swallowing assessment (DSR1), the time to initiate oral feeding (TOF) and the amount of individual treatment (RVU) were related to a higher probability of reaching good treatment outcomes for dysphagia resolution. Among these indicators, the DSR1 is the strongest predictor. Also, the DSR1 correlated significantly with the TOF (that is the higher the ASHA NOMS level at the initial swallowing assessment the less time is needed to initiate oral feeding) and with the RVU (that is the higher the ASHA NOMS level at the initial swallowing assessment the less intervention is needed by a therapist). This finding validates the importance of the initial assessment determining the outcome of a patient with dysphagia following prolonged OTI [18].

In accordance to our results, previous researchers also found that neither age nor the duration of intubation appears to be a significant factor affecting oral intake [1, 18, 25, 36]. The literature indicates the age variable as being implicated in the presence and resolution of the swallowing impairment [8, 16, 21]. However, our study suggests that the age variable did not seem to significantly interfere in the resolution of dysphagia. According to the criteria adopted in our hospital (that is public, high complexity, high rate of bed turnover), once patients reach adequate stable clinical conditions, they are discharged. In many cases, functional swallowing has not yet been reached. According to the Brazilian Health System, patients will receive speech-language pathology follow-up in specialized health care centers. For this reason 59 patients (approximately 40% of the individuals) were discharged from the hospital even though they did not reach a good dysphagia resolution. We believe that if these patients were followed until dysphagia resolution, our results would probably indicate significant differences regarding the variable age.

The association between intubation duration and severity of dysphagia is supported by the Barker et al. review [15] and other studies [6, 15]. However, this association has not been reported in other analyses [1, 8, 12, 37, 38]. The study presented by Stauffer et al.[38] indicated no correlation between the duration of endotracheal intubation in intubated patients and the severity of laryngeal lesions. Many factors could account for this discrepancy, such as differences in sample size, event rate and intubation duration. Although this association is plausible based on the likely increased degree of oral, pharyngeal and laryngeal damage in patients intubated for long periods, it also remains possible that short intubation duration is sufficient to cause dysphagia [39]. The association between intubation duration and dysphagia most certainly needs to be further explored.

We would like to highlight that the result related to the time to initiate oral feeding. Based on our results, we believe that the earlier oral feeding is introduced the higher the probability of reaching good dysphagia outcomes. We also found positive results regarding the recovery of swallowing impairment until dysphagia resolution/hospital discharge. We observed that most patients presented a favorable progression of oral intake. This general pattern of improvement in the swallowing ability during the length of hospital stay is similar to the pattern of positive outcomes that have been previously reported in the specialized literature [17, 18, 25].

Our study also showed that poorer swallowing status at the initial swallowing assessment is a good indicator of longer swallowing management. Our findings agree with those of other studies in that preadmission functional status was also a highly relevant prognostic factor of amount of treatment (that is RVU) [14, 18, 40]. Previous studies suggest that a lack of accuracy in initial evaluation could impact both the dietary level assigned to patients and therefore the amount and type of treatment received [18]. The use of functional rating scales to evaluate patients with swallowing disorders has emerged over the past years [27, 41‐43]. Several screening methods for dysphagia have been validated [44‐46]. In this study, a validated reliable clinical bedside protocol was used.

Finally, our study had several limitations. First, the results of this study have been derived from a hospital-referred cohort of patients after prolonged OTI and therefore may reflect some hospital-referral bias. Second, the conclusions drawn can only be applied to patients exhibiting some degree of dysphagia as previously discussed. Third, the clinical assessment of impaired swallowing has evident limitations and a videofluoroscopy (VFS) examination would be required for all patients. However, clinical examination, cervical auscultation and oximetry changes (that is BSE) increased the diagnostic sensitivity, and thus, the probability of identifying patients with silent aspiration [45]. Also we have to consider that although VFS is the gold standard to study oral and pharyngeal mechanisms of dysphagia and aspiration [39, 47, 48], it is unfeasible to perform a VFS on every patient with dysphagia (that is age, medical condition, costs and so on). A simple BSE can be used to identify patients at risk for dysphagia after prolonged OTI [6]. Third, inherent in the design of our retrospective, observational cohort study is an inability to draw conclusions about the severity of the diseases of the patients included in the study. Since patients were recruited from different ICUs of our hospital, we were unable to reach a consensus of which information could be used to characterize patients’ clinical status severity (that is each ICU uses a different protocol to determine disease severity). Similarly, some very important variables were inconsistently charted or not charted at all, thus were not available for our analysis. For example, we were unable to obtain (1) a reliable marker of sedation at the time of swallow assessment; (2) height data to calculate body mass index; (3) data on the presence of preexisting swallowing dysfunction; (4) information about endotracheal tube size. Future studies in our institution will most certainly include these variables.

Dysphagia is a major side effect of prolonged OTI. Prognostic data can be beneficial to health professionals, rehabilitative facilities providing care, insurance companies, and patients and their families. When looking at developing countries, the prolonged intensive medical and nursing care required by many patients places extra demands on a stretched health care budget [49]. Knowing the statistically significant factors that contribute to patient outcome as determined by this study reiterates the urgency for accuracy and consistency during the initial assessment within a health facility.

The main contribution of the current research is related to the swallowing functional level at admission as a significant prognostic indicator of good swallowing outcome (that is ASHA NOMs level 6/7). The level of swallowing impairment, the time to initiate oral feeding and the amount of individual treatment can be used as clinical indicators to predict swallowing rehabilitation outcomes.

Given the current trend of having an evidence-based practice, studies of prognostic indicators in different populations with dysphagia can contribute to the design of more effective procedures when evaluating, treating, and monitoring individuals with this type of disorder. We believe that the measurement of prognostic indicators for swallowing rehabilitation outcomes should be routinely included in interdisciplinary hospital practice.