Abstract
This study aims to evaluate the histological changes in the nasal mucosa post Tracheostomy. A prospective observational study was done on 30 patients undergoing Tracheostomy after obtaining written informed consent from patients/legally accepted representatives. Prior to Tracheostomy, anterior rhinoscopy was done, and findings were noted; nasal mucosal biopsy was obtained from the inferior turbinate. The patients enrolled were followed up for four weeks, and in the patients still having Tracheostomy, repeat inferior turbinate biopsies were taken and compared. Statistically significant atrophy of lining epithelium was seen in 80% of the subjects, i.e., pseudostratified lining epithelium at Baseline with multilayered appearance changed to a single layer of flattened cells at follow-up. There was also a marked reduction in the number of seromucinous glands in the stroma at follow-up in 80% of the subjects. Additionally, fibrosis in the stroma was noted in 43.3% of subjects at follow-up. The results from this study indicate that Tracheostomy, likely as a result of nasal airflow deprivation, brings about significant changes in the microanatomy of the nasal airway. The extent of this causation and its implication in nasal pathology must be studied in larger populations with extended follow-up periods.
Keywords: Nasal airway, Tracheostomy, Nasal mucosal atrophy, Nasal airflow deprivation
Introduction
Tracheostomy is a common surgical procedure to secure a more permanent airway. It completely bypasses the upper respiratory tract and provides a new route for the passage of air. There are several hypotheses related to the effects of total airflow deprivation on the upper airway, mainly the nasal airway, but very few studies confirm these. There is evidence of increased nasal symptoms in patients post Tracheostomy [1, 2]; however, these have not been studied in detail.
Turbulent nasal airflow (e.g., relating to a septal deviation) is known to lead to a localized drying of the epithelium, with changes in mucociliary transport, nasal crusting, and microbiological flora leading to dysfunction. It is also suggested that some airflow is necessary for normal mucosal function, so inadequate flow may be equally likely to cause pathology. Inadequate nasal airflow has been shown to cause drying of the nasal epithelium, impairment of nasal mucociliary clearance, and changes in mucosal color, thickness, and function.
The normal nasal histology is closely linked with the physiological roles of the nasal airway, such as the pseudostratified ciliated epithelium, which is responsible for the ciliary beat; the nature and amount of mucus produced by the serous and seromucous glands affect the mucous blanket which in turn plays a role in effective mucociliary clearance.
Hence, Tracheostomy, by cutting off nasal airflow, thereby affecting nasal epithelial structure and mucociliary function, is thought to be an important causative factor in nasal and paranasal sinus infection [2–4].
Methods
This prospective observational study was done in Tertiary Care Hospital after obtaining ethical clearance from the Institutional Ethics Committee. 30 patients who were to undergo Tracheostomy between the ages of 19 and 74 were included in the study. Written informed consent was obtained from the patients/ legally accepted representatives. After enrolling patients in this study, demographic data of all patients was taken before Tracheostomy.
Inferior turbinate biopsy was obtained after topical anesthesia with 4% Lignocaine solution using straight Weil-Blakesley thru-cut forceps. Haemostasis post biopsy was achieved by anterior nasal packing and instilling Haemocoagulase nasal drops (Botroclot®). Biopsy specimens were sent to the Histopathology laboratory in formalin for processing. Paraffin embedded blocks were prepared, and Hematoxylin and Eosin stained slides were obtained for light microscopic examination. Patients were followed up for one month, and nasal mucosal biopsy was repeated in those still on Tracheostomy.
The histological findings were recorded as follows: Lining epithelium-pseudostratified (normal) or atrophic; Sub-epithelium—number of sero-mucinous glands, whether normal or reduced; and presence of fibrosis.
MS Excel and SPSS version 22 (IBM SPSS Statistics) were used to analyze data.McNemar’s test was used as the test of significance.
Results
Of the 30 subjects enrolled, the majority were Neurosurgical patients with low GCS (glasgow coma scale) scores (53%), followed by ICU (intensive care unit) patients on prolonged ventilation (30%).
At Baseline 29 i.e., 96.6% of patients had normal, Pseudostratified lining epithelium and abundant seromucinous glands in the sub-epithelium. At follow-up, 80% had atrophied lining mucosa and a reduced number of seromucinous glands. An evident change in appearance in nasal mucosa was noted in the majority of the subjects, i.e., from pseudostratified lining epithelium with a multilayered appearance at Baseline (Fig. 1) to a single layer of flattened cells at follow-up (Fig. 2). The number of seromucinous glands was found to be reduced at follow-up (Fig. 2).
Fig. 1.
Histology of Nasal Mucosa at Baseline: H & E, × 200, showing: a pseudostratified (thick) lining mucosa; b Fibroconnective tissue & c Abundant seromucinous glands in the sub-epithelium
Fig. 2.
Histology of Nasal Mucosa at follow-up: H & E, × 200, showing: a atrophied (thinned) lining mucosa; b reduced seromucinous glands in the sub-epithelium & c areas of Fibrosis
Among patients with normal baseline epithelium and abundant seromucinous glands, 95.8% developed atrophied lining epithelium and a reduced number of seromucinous glands. The McNemar χ2 value of 21.043 exceeds the critical χ2 value of 3.84 with 1 df and is thus statistically significant at a p-value of 0.05.
Additionally, amongst the 80% of patients who had reduced seromucinous glands in follow-up, 13 subjects, i.e., 54.1%, had areas of fibrosis in the sub-epithelium (Fig. 2). Overall, 43.3% of patients developed fibrosis at follow-up.
Discussion
The incidence of Tracheostomies performed has been increasing worldwide with the advancements in critical care and growing numbers of admissions in intensive care. Tracheostomy is performed in approximately 10–15% of patients admitted to intensive care units (ICU). While the various respiratory and mechanical ventilation related complications of Tracheostomy have been widely studied and debated, little is known about the effect of Tracheostomy on the nasal airway.
This study shows that Tracheostomy brings about significant changes in the microstructure of the nasal mucosa. It has been established that the nasal structure affects its physiological role and vice-versa [3, 5].
It was found in this study that there was significant atrophy in lining epithelium affecting 80% of the subjects at follow-up, which is in keeping with the findings of El-Sharnouby et al. [3]. It was also found that there was fibrosis of the stroma and significant change in the sub epithelium to a reduced number of seromucinous glands post Tracheostomy, which matches the findings of Karaca et al. [6] and Riva et al. [10].
Other authors report no early changes change in lining epithelium and an initial increase in the number of seromucinous glands at 2 months post Tracheostomy and a later atrophied lining epithelium and a decrease in the number of seromucinous glands at 6 months post Tracheostomy [3].
A study done on long-term nasal mucosal changes in laryngectomees (i.e., those who have essentially undergone permanent Tracheostomy) postoperative for a period ranging from 6 to 84 months demonstrated one or more of the following abnormalities: atrophic epithelium, destruction of goblet cells, subepithelial glands and cilia, fibrosis of stroma, neovascularization, congestion, and myxoid degeneration of the stroma. The most common observation was the destruction of goblet cells and the stroma [6].
Several hypotheses to explain this phenomenon exist, such as the lack of physiological irritants to the nasal mucosa leading to the disappearance of the multilayered nasal epithelium and goblet cells [7]. It has also been proposed that the reduction in the amount of secretions from the reduced number of glands and the decrease in Relative Humidity further contributes to ciliary destruction [6]. Changes in the endonasal temperature and Relative Humidity, along with the epithelial changes, also affect Nasal Mucociliary clearance. Maurizi et al. suggest that an impaired mucociliary clearance predisposes to secondary infection by saprophytic bacteria and consequent inflammation, leading to further alterations in mucosal characteristics [8].
Therefore, it can be concluded that the separation of the nasal airway from the lower respiratory tract by means of Tracheostomy initiates a cascade of structural and physiological alterations in the nasal airway with significant interplay amongst them.
Conclusion
This study shows atrophy in the lining epithelium of the nasal mucosa and a reduced number of seromucinous glands with areas of fibrosis in the stroma in the subepithelium following Tracheostomy. These results indicate that Tracheostomy, as a result of nasal airflow deprivation, brings about significant changes in the microanatomy of the nasal airway. This could explain the impaired nasal mucociliary clearance in ICU patients. ICU patients, particularly immunocompromised patients, including diabetics, are at increased risk of lower and upper respiratory infections [9].
The extent of this causation needs to be studied in larger populations with more extended follow-up periods. The role of Tracheostomy in causing nasal disease, i.e., CRS (Chronic Rhinosinusitis) with complications, with or without fungal involvement in patients on prolonged Tracheostomy, should also be characterized so that screening protocols and early prevention may be instituted.
Declarations
Ethical approval
This study was conducted after obtaining the approval of the Institutional Ethics Committee. Written informed consent was obtained from subjects/ their legally accepted representatives before enrolment into the study. There are no conflicts of interest associated with this publication and no financial support has been received for this study.
Footnotes
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