Introduction
Rigid nasal endoscopy is an indispensable diagnostic tool in contemporary ENT out-patient practice, enabling detailed visualisation of the nasal cavity and nasopharynx. A commonly encountered technical limitation during endoscopic examination is fogging of the lens, which compromises image clarity and may necessitate repeated scope withdrawal, cleaning and reinsertion, thereby prolonging the procedure and reducing patient comfort.Reference Stammberger and Posawetz1
Several techniques have been employed to prevent endoscopic lens fogging, including chemical antiseptic solutions, warm saline immersion, heated air systems and commercially available anti-fog agents.Reference McCoul, Ganeshan and Nguyen2 In many resource-constrained settings, antiseptic solutions such as Savlon are frequently used because of their accessibility and perceived dual role in defogging and disinfection. However, Savlon contains chlorhexidine and cetrimide, agents known to possess irritant and cytotoxic potential when applied to delicate mucosal surfaces.Reference Gilbert and Moore3
Current post-operative nasal care practices increasingly discourage the application of antiseptic solutions to the nasal mucosa, favouring isotonic saline because of its superior tolerability and preservation of mucociliary function.Reference Rudmik and Smith4
Despite this, there remains a lack of clinical studies evaluating the mucosal effects of commonly used endoscopic defogging agents during routine diagnostic nasal endoscopy. This pilot study was therefore undertaken to compare Savlon and warm sterile saline with respect to both defogging efficacy and nasal mucosal tolerance.
Materials and methods
Study design and participants
This prospective pilot comparative study was conducted in the Department of Otorhinolaryngology at a tertiary care centre. Adult patients (≥18 years) undergoing diagnostic nasal endoscopy for evaluation of nasal symptoms were consecutively recruited. Written informed consent was obtained from all participants prior to inclusion in the study.
The study involved comparison of two defogging methods that are routinely used in standard clinical practice during diagnostic nasal endoscopy with zero risk. No additional intervention, experimental drug or deviation from routine care was introduced. As the study was conducted as part of routine clinical practice and involved minimal risk to participants, formal Institutional Ethics Committee approval was not sought. The study adhered to institutional clinical governance policies and was conducted in accordance with the principles of the Declaration of Helsinki.
The datasets generated and analysed during the current study are available from the corresponding author on reasonable request.
Patients with recent nasal surgery, active epistaxis, known hypersensitivity to antiseptic agents or severe septal deviation precluding adequate endoscopic examination were excluded.
Group allocation
Participants were allocated into two equal groups (n = 20 each) using a computer-generated random number sequence by a resident not involved in outcome assessment: Group A (Savlon group), endoscope lens defogged using diluted chlorhexidine–cetrimide solution (Savlon) prepared at a concentration of 1:200, and Group B (warm saline group), endoscope lens defogged using warm sterile normal saline maintained at 40–45°C.
Neither patients nor the examiner were blinded to the defogging method used.
Endoscopic procedure
All procedures were performed using a standard 0° rigid nasal endoscope. Topical decongestants and local anaesthetic sprays were not used to avoid confounding effects on the nasal mucosa. Immediately prior to insertion, the distal tip of the endoscope was dipped in the assigned defogging agent. Endoscopy was performed using a standardised technique by a single examiner.
Outcome measures
Endoscopic visualisation
Endoscopic visualisation was assessed using a predefined endoscopic visualisation score. The score description was as follows: 0, no fogging, excellent visualisation; 1, minimal fogging without interference; 2, moderate fogging with brief interference; 3, severe fogging requiring scope withdrawal.
Subjective procedure-related discomfort assessment
Subjective patient experience was assessed immediately following completion of the procedure using a structured assessment. Overall discomfort was measured using a 10-point visual analogue scale (VAS). The presence of a burning or stinging sensation was recorded as a binary response (yes or no). Overall procedure tolerability was graded as good, acceptable or poor.
Nasal mucosal irritation
Nasal mucosal irritation was assessed based on visible mucosal erythema during endoscopy and/or patient-reported burning sensation at the time of scope insertion.
Repeat defogging requirement
The need for repeated withdrawal and re-defogging of the endoscope due to impaired visualisation was recorded.
Statistical analysis
Continuous variables were expressed as mean ± standard deviation and compared using the independent student’s t-test. Categorical variables were expressed as frequencies and percentages, and compared using the chi-square test. A p value less than 0.05 was considered statistically significant.
Results
Forty patients were included in the analysis, with 20 patients in each group. Baseline characteristics and clinical indications for nasal endoscopy were comparable between groups.
Endoscopic visualisation
The mean endoscopic visualisation score was 0.60 ± 0.50 in the Savlon group and 0.45 ± 0.51 in the warm saline group, with no statistically significant difference between groups (p = 0.34) (Table 1).
Comparison of endoscopic visualisation and patient discomfort between groups
Table 1 Long description
The table compares endoscopic visualisation and patient discomfort between two groups: Savlon and warm saline, each with 20 participants. Endoscopic visualisation scores were similar between Savlon (0.60 ± 0.50) and warm saline (0.45 ± 0.51), with no significant difference (p = 0.34). However, patient discomfort scores on a 10-point visual analogue scale were significantly lower for the warm saline group (2.1 ± 1.1) compared to the Savlon group (4.2 ± 1.3), with a p-value of less than 0.001, indicating a statistically significant reduction in discomfort with warm saline.
Endoscopic visualisation was assessed using a predefined objective scoring system. Patient discomfort was assessed immediately after the procedure using a 10-point visual analogue scale). SD = standard deviation
Subjective discomfort and tolerability
Patient-reported discomfort scores were significantly higher in the Savlon group (VAS, 4.2 ± 1.3) compared with the warm saline group (VAS, 2.1 ± 1.1; p < 0.001). Burning or stinging sensation was reported more frequently in the Savlon group. A greater proportion of patients in the warm saline group rated the procedure as well tolerated (Table 2).
Comparison of subjective tolerance, mucosal irritation and repeat defogging
Table 2 Long description
The table compares subjective tolerance, mucosal irritation, and repeat defogging between Savlon and warm saline in a sample of 20 each. Warm saline resulted in higher procedure tolerability at 80% compared to 45% for Savlon, with a statistically significant p value of 0.02. Burning or stinging sensation was reported by 35% of Savlon users versus 10% for warm saline, with a p value of 0.04, indicating a significant difference. Repeat defogging was required in 20% of Savlon cases and 10% of warm saline cases, but this difference was not statistically significant (p = 0.38). Overall, warm saline appears to be better tolerated with less mucosal irritation.
Subjective tolerance was assessed immediately after the procedure. Mucosal irritation was defined by visible mucosal erythema and/or patient-reported burning or stinging sensation. Repeat defogging refers to withdrawal of the endoscope due to impaired visualisation.
Nasal mucosal irritation and repeat defogging
Visible mucosal erythema was observed in 6 of 20 patients (30 per cent) in the Savlon group compared with 1 of 20 patients (5 per cent) in the warm saline group. This difference was statistically significant (chi-square test, p = 0.04).
Repeat defogging was required in 4 patients (20 per cent) in the Savlon group and 2 patients (10 per cent) in the warm saline group; this difference was not statistically significant (p = 0.38). Although repeat defogging was numerically higher in the Savlon group, the difference did not reach statistical significance. This may be attributable to the small sample size and limited statistical power inherent to a pilot study. A larger adequately powered study may detect clinically meaningful differences between the groups.
Adverse effects
No delayed adverse effects, including epistaxis, persistent nasal irritation or excessive dryness, were reported at 24-hour follow up in either group.
Discussion
This pilot study highlights an often overlooked aspect of routine nasal endoscopy, namely the effect of defogging agents on nasal mucosal tolerance. Although antiseptic solutions such as Savlon are effective in preventing lens fogging, their potential to cause mucosal irritation raises clinical concerns, particularly in patients with inflamed nasal mucosa or those undergoing repeated endoscopic examinations.
Warm sterile saline demonstrated defogging efficacy comparable to Savlon while offering superior patient comfort and minimal mucosal irritation. The defogging effect of warm saline is largely attributable to temperature equilibration, which prevents condensation on the lens surface.Reference Wormald5 Unlike chemical antiseptics, saline is physiologically compatible with the nasal mucosa and does not adversely affect mucociliary function.
Given its simplicity, safety and low cost, the routine use of warm saline as a defogging agent may enhance patient experience without compromising procedural quality. This has particular relevance in high-volume ENT out-patient settings, where even minor improvements in patient comfort can significantly impact overall workflow efficiency.
While commercially available anti-fogging agents and heated endoscopic systems are widely used in tertiary centres, such devices may not be readily available in smaller hospitals or resource-constrained settings. Both Savlon and warm sterile saline are inexpensive and universally accessible solutions. The findings of this study therefore have particular relevance in settings where dedicated anti-fogging preparations are unavailable.
The limitations of this study include its small sample size and single-centre design. Larger multicentric studies incorporating objective assessments of mucociliary function would further validate these findings.
• Fogging of the endoscopic lens is a frequent problem during diagnostic nasal endoscopy and may interrupt the procedure
• Chemical antiseptic solutions such as Savlon are commonly used as defogging agents in routine clinical practice
• Warm sterile saline provides defogging efficacy comparable to Savlon during diagnostic nasal endoscopy
• Warm saline is better tolerated by the nasal mucosa and is associated with reduced patient discomfort compared with Savlon
• Warm sterile saline represents a safer and well-tolerated alternative to Savlon, particularly in resource-limited settings
Conclusion
Within the limitations of the pilot study, warm sterile saline provided effective endoscopic lens defogging with better nasal mucosal tolerance than Savlon. These findings suggest that warm saline may be a well-tolerated alternative for endoscopic lens defogging, especially in resource-limited settings. However, larger controlled studies are required before recommending changes to routine clinical practice.
Acknowledgements
The authors would like to acknowledge the co-operation of all patients who consented to participate in this study. We also thank the nursing staff and residents of the Department of Otorhinolaryngology for their assistance during patient recruitment and endoscopic procedures. Their support was invaluable in the smooth conduct of this study. AI was used for language precision during manuscript preparation (ChatGPT).
Competing interests
None declared
