Discussion:

In 1981, Puchelle et al. showed that the saccharin test could be used as a useful screening test in nasal mucociliary clearance.[2] Various authors have also shown that saccharin test is advantageous over other modalities of investigation. Hence to assess the impact of tracheostomy on nasal mucociliary clearance, a saccharin test was performed.
In 1995, Kleinschmidt et al. used the saccharin test and showed a saccharin transit time (STT) of 624 seconds in healthy subjects while the present study showed a mean STT of 447.4±63.2 seconds in control group.[3]
Similar studies were done by Yergin et al., Stanley et al. showed a mean STT of 432 seconds, 702±228 seconds, respectively, in healthy subjects. Such variations in average mucociliary clearance time are attributed to various factors such as habits, habitat, climate, facial configuration, and comorbidities [4, 5, 6]. A study done by Golhar et al. on 150 subjects from India revealed a mean nasal mucociliary clearance time of 430 seconds (range: 320- 700 seconds) which was consistent with the results of the present study. Golhar further stressed that the saccharin test could be used as a valid screening test, not only for the diagnosis of nasal mucociliary impairment but also for the prognosis of various diseases of nasal and lower respiratory tracts [7]. Karaoglu D et al. conducted a study in which they studied the long-term effects of laryngectomy on nasal functions and found that mean mucociliary clearance time for laryngectomized patients was 1017.14 seconds whereas in control group it was 662.5 seconds suggesting that physiological alteration in the nose due to bypass of nasal airway, leads to reduced ciliary clearance and impaired olfaction which can affect patients quality of life and safety. [8]
In our study, mean nasal mucociliary clearance time (NMCT) was 934.97±75.9 seconds, these results were similar to study done by El-Sharnouby et al. who conducted a study on 31 patients and found that the mean saccharine test time recorded 2 months following tracheostomy was 732.6± 323.4 seconds and at 6 months postoperatively was 1615±1042 seconds and was statistically significant.[9]However, study done by Yadav SP et al. on 30 tracheostomized patients showed nasal mucociliary clearance time of 444±22.8 seconds when saccharin test was done at 3 weeks following tracheostomy and NMCT further reduced to 371.4±32.4 seconds in patients who were tracheostomized for more than 3 weeks, suggesting that, following tracheostomy, there is a significant decrease in nasal mucociliary clearance time, particularly after 3 weeks postoperatively.[10]
A study was done by Tsikoudas A et al. in 2011 on 10 subjects in cases and control arms respectively, where the author used SNOT-22, and Rhinogram nasal symptoms score questionnaires and found that tracheostomy group had a median Rhinogram score of 13.5 vs. 2 for the control arm (p=0.02), and similarly SNOT-22 scores for tracheostomized patients and controls were 39 and 29 respectively (p=0.205), thereby observing that the tracheostomy group had more nasal symptoms due to worsening of mucociliary clearance, which supports the hypothesis of this present study and author concluded by stressing that this impairment in nasal mucociliary clearance following tracheostomy should be addressed in follow up as altered nasal function can predispose patients to sinonasal diseases and a reduction in olfaction causing poor identification of smell of food leading to a poor quality of life and could become potentially dangerous in situations like gas leak.[11]
Smaller sample size was one of the limitations of this study hence further studies with larger sample size and follow-up can be done to better understand these changes in nasal mucocilia and whether these changes are reversible following decannulation, additionally we can also determine whether techniques like polite yawning etc. can be used to improve nasal mucociliary physiology and olfaction in these tracheotomised patients.