A preliminary study was carried out using a fiberoptic endoscopic evaluation of post-intubation laryngeal injuries in a 20-bed medical ICU (Hopital Européen Georges Pompidou, Paris).
Then, we performed a prospective study over a 1-year period in our Intensive Care Unit admitting mostly medical patients at the Rennes University Hospital, a tertiary teaching hospital. This study was approved by the hospital’s ethical committee (no. 16.143). As FEES is considered routine care in our ICU to assess SD for recently extubated survivors of critical illness, patient informed consent was waived by the ethical committee.
Criteria for inclusion were as follows: intubation for more than 48 h; extubation after a successful weaning trial of 1 h through a T-piece; ability to maintain a sitting position; Glasgow coma scale after extubation of 15.
Exclusion criteria were a known laryngeal pathology, a preexisting swallowing disorder and an admission for stroke. We also excluded all patients for whom we were unable to perform the BSE or FEES within the first 24 hours following extubation and all patients who refused FEES.
All patients were orally intubated with soft, high-volume, low-pressure cuffed endotracheal tube (ETT) (Mallinckrodt Medical, Athlone, Ireland). All intubations were performed by experienced intensivists. During the ICU stay, cuff pressures were checked every 4 h to maintain a pressure < 25 cmH2O.
Extubation was decided by the patient’s attending physician after a successful 1h spontaneous breathing trial. Planned extubations were performed by respiratory therapists as previously reported.
According to the preliminary study, the BSE comprised a clinical evaluation of eight items as shown in Table 1. The items included in the BSE were chosen to explore the first phases of normal swallowing, according to the previous identified risk factors, and a retrospective analysis of factors present in patients whom had a SD. Thus, the oral praxis skills, salivary stasis and mobility of the tongue explore the oral phase; tone of the flexor muscles of the neck and ability to maintain head lifted explore the pharyngeal phase; voluntary coughing and clear voice explore the signs of aspiration; and the post-extubation stridor explore the presence of laryngeal injuries. Post-extubation stridor was defined as an audible inspiratory wheeze after extubation. Each item was counted as one point. Therefore, the possible scores for the BSE ranged from 0 to 8.
A bedside evaluation was conducted within 24 h after extubation by two physiotherapists and before the FEES procedure. The BSE was performed without knowledge of the FEES results. Reproducibility of the BSE between the two physiotherapists, several nurses and physicians was tested on the 30 first patients.
A laryngeal nasofibroscopy was performed within 24 h after extubation by two experienced otolaryngologists. The FEES procedure was performed in bed or on a chair for all patients with the back elevated to at least 75°. A fiberoptic laryngoscope (Karl Storz Endoskope™ 11101SP, Tuttlingen, Germany, 30 cm long and of 3.5 mm diameter was used with a Karl Storz™ 11301 DF cold light supply for illumination) was passed transnasally to the nasopharynx, oropharynx, and supraglottic area to allow adequate visualization of the structures involved in swallowing. No topical anesthetic or other preparation was used before placing the scope in the nose. Gastric tube, if it was present, was not removed during the procedure. Stained liquid and semi-liquid boluses were then given. Otolaryngologists assessed the ability to protect the airway and to uphold airway protection, the capability to clear the bolus during deglutition, the presence of pooling and residual material in the hypopharynx. We defined swallowing disorder (positive FEES) as a Penetration Aspiration Scale (PAS) > 1 (Supplementary Table 1). The FEES was performed after BSE, without knowledge of the BSE result.
We prospectively collected the following parameters: age, sex, body mass index (BMI), severity of illness at admission according to the simplified acute physiological score (SAPS II) and the sequential organ failure assessment score (SOFA) at admission, main indication for intubation (neurologic failure, acute respiratory failure, hemodynamic failure and surgery), intubation characteristics (emergency or planned for surgery), use of sedation or myorelaxant drugs for intubation, the duration of intubation, ETT diameter (expressed in millimeters) and patient’s height/ETT diameter ratio, history of self-extubation, and the number of intubations during ICU stay before inclusion. We also recorded if patients had a shock (a need for dobutamine, epinephrine, or norepinephrine treatment during intubation period), if they received steroids prior to extubation (at least 50 mg equivalent of methylprednisolone per day during the period of intubation) and their SOFA score at the day of extubation. After extubation, the patients were monitored for 28 days and the following parameters were recorded: extubation failure (defined as the need to reintubate the patient in the first week following extubation, regardless of cause), the development of pneumonia within 28 days after extubation, ICU length of stay, and vital status within 28 days after extubation.
The primary endpoint was the accuracy of the BSE compared to the FEES procedure. Secondary endpoints were the incidence of SD, pneumonia and death occurrence within the 28 first days, and to identify risk factors for SDs.
Based on the literature and our preliminary study, we hypothesized a prevalence of 0.30 and an expected sensitivity of 0.80 with a minimal lower confidence interval of 0.6; these estimates allowed us to calculate a sample size of 76 patients.
Normally distributed continuous variables are presented as the means ± standard deviations (SDs), whereas non-normally distributed data are presented as medians [Interquartile ranges (IQRs)]. Categorical variables are presented as numbers (percentages). We identified risk factors for swallowing disorder using univariate and multivariate analysis. The two groups (normal swallowing vs. swallowing disorder) were compared using the Mann-Whitney test for continuous variables and a χ2 or Fisher’s exact test when more appropriate for categorical variables. A descendant stepwise logistic regression analysis was performed to determine the independent factors of swallowing disorders with p=0.20 for enter. Among related factors (SAPS II at admission and SOFA at intubation) only the most clinically relevant (SAPS II for severity) were included in the multivariate analysis model to minimize the effect of collinearity. Thus, the variables entered into the multivariate analysis were SAPS II at admission, hemodynamic failure, intubation characteristics (emergency or planned for surgery), duration of intubation and main indication for intubation. The findings of the FEES were considered the gold standard and were compared with the results of BSE. Ninety-five percent confidence intervals (95% CI) were calculated as exact binomial confidence intervals. The accuracy of the BSE was assessed by the mean of receiver operating characteristics (ROC) curves and the area under curve (AUC). The threshold value of the BSE was then determined from analysis of the ROC curves as the value that led to the best compromise between sensitivity and specificity. Statistical analyses were performed using R 3.6.2 (R Foundation for Statistical Computing, Vienna, Austria), and p values of less than 0.05 were considered significant.