Nasal saline irrigation: a clinical update

Abstract

Background

Nasal saline irrigation (NSI) plays an important role in the treatment of chronic rhinosinusitis (CRS). It is a beneficial low-risk treatment that serves an adjunctive function in the medical and surgical management of CRS. NSI is hypothesized to function by thinning mucous, improving mucociliary clearance, decreasing edema, and reducing antigen load in the nasal and sinus cavities. Although its use in CRS is nearly universal, significant variety exists with regard to delivery volume, delivery pressure, frequency of use, duration of use, composition, and hygiene recommendations. Evidence is limited regarding the most optimal methods of NSI delivery. In addition, use of NSI has recently come under increasing scrutiny due to potential associations with cases of primary amebic meningoencephalitis.

Methods

In this review we provide a clinical update summarizing use of NSI for treatment of CRS, including current recommendations for use, and data regarding overall efficacy, available delivery devices, solution composition, and hygiene.

Results

Current evidence and recommendations for nasal saline delivery methods, composition, and hygiene are presented.

Conclusion

The most recent consensus statements and Cochrane Review recommend the use of NSI for CRS based on a preponderance of lower level evidence. A conclusion regarding the optimal method of delivery and solution composition cannot be drawn based on the current literature.

Nasal saline irrigation (NSI) plays a major role in the treatment of chronic rhinosinusitis (CRS). It is a beneficial low-risk treatment that serves an adjunctive function in the medical and surgical management of CRS. NSI is hypothesized to function by thinning mucous, improving mucociliary clearance, decreasing edema, and reducing antigen load in the nasal and sinus cavities.1 Although its use in CRS is nearly universal, significant variety exists with regard to delivery volume, delivery pressure, frequency of use, duration of use, composition, and hygiene recommendations. Evidence is limited regarding the most optimal methods of NSI delivery. In addition, use of NSI has recently come under increasing scrutiny due to potential associations with cases of primary amebic meningoencephalitis. This review provides a clinical update summarizing use of NSI for treatment of CRS, including current recommendations for use, and data regarding overall efficacy, available delivery devices, solution composition, and hygiene.

Current recommendations and evidence

High-volume (>200 mL) NSI as an adjunct to other medical therapies for CRS is strongly recommended in the 2016 International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (Table 1).1 The 2012 European Position Paper on Rhinosinusitis and Nasal Polyposis recommends NSI for CRS without nasal polyps as an adjunct to medical and surgical therapy (Table 1).2 Both position papers support their recommendations with a grade A level of evidence.1, 2 Despite these recommendations, a lack of high-quality evidence confirming NSI clinical efficacy in CRS remains. In addition, a consensus on the optimal method of delivery and saline composition does not exist. The use of NSI for CRS was systematically evaluated in a 2016 Cochrane Review (Table 1).3 Only 2 studies met inclusion criteria for the review.3 One study compared high-volume (150 mL) hypertonic (2%) saline (HS) vs no treatment.4 Patients treated with high-volume HS showed a significantly greater improvement in their disease-specific health-related quality of life (HRQL) scores when compared with no treatment at 3 and 6 months.4 The review determined that the overall quality of evidence was low for the 3-month outcomes and very low for the 6-month outcomes.3 The other included study compared twice-daily nebulized (5 mL) nasal saline with intranasal corticosteroids.5 The intranasal corticosteroid group had a significantly greater improvement in their symptom and endoscopy scores when compared with the nasal saline group at 3 and 6 months.5 The review determined that the overall quality of evidence in the study was very low.3 Ultimately, the 2016 Cochrane Review concluded that NSI should be strongly recommended as a potentially beneficial low-risk treatment option for CRS. Definitive conclusions regarding overall efficacy in CRS in comparison to other CRS treatments, and the most clinically effective method of delivery, could not be drawn from the currently available literature. Nonetheless, recent and previous studies not meeting inclusion criteria for the Cochrane Review have drawn meaningful conclusions related to many of these important topics.

Table 1. Consensus statements and Cochrane Review

• CRS = chronic rhinosinusitis; CRSsNP = chronic rhinosinusitis without nasal polyps; CRSwNP = chronic rhinosinusitis with nasal polyps; NSI = nasal saline irrigation.

Nasal saline delivery

A wide variety of nasal saline delivery products are commercially available, including low-volume, high-volume, powered high-pressure, and powered nebulized devices. Several studies have evaluated factors (extent of surgery, head position, and type of delivery device) with the potential to impact irrigation penetration into the paranasal sinuses.6-11 NSI has minimal sinus penetrance in patients who have not undergone surgery,12 but is positively correlated with the extent of functional endoscopic sinus surgery (FESS).12 A 2013 systematic review by Thomas et al concluded that evidence supports use of a high-volume device in the head-down-and-forward position for optimal paranasal sinus delivery (Table 2).6

Table 2. Literature on optimal NSI delivery

• FESS = functional endoscopic sinus surgery; HDF = head down forward; MT = middle turbinate; NSI = nasal saline irrigation.

More recent evidence has expanded our understanding of how head position and extent of surgery influence NSI distribution. A 2017 cadaver study by Craig et al addressed the impact of head position on the penetration of irrigation to the sphenoid sinuses using a computational fluid dynamics model (Table 2).7 It was determined that the nose-to-ceiling position was more effective than the head-down-and-forward position at delivering irrigation to the sphenoid sinuses.7 This position should be considered in cases of recalcitrant sphenoid sinusitis.7 A 2017 cadaver study by Halderman et al evaluated the influence of middle turbinate (MT) resection on the penetrance of solution delivered by a powered nasal nebulizer (Table 2).8 The study showed that partial MT resection resulted in increased penetrance into the frontal and sphenoid sinuses and complete MT resection resulted in increased penetrance into all sinuses.8 The authors did not recommend routine MT resection, but did recommend that it be considered in cases with expected recalcitrance where paranasal sinus penetrance of topical therapy is paramount.8

Low-volume devices include nasal saline sprays (low-volume squeeze bottles, pumps, and mechanized devices) and nonpowered nasal nebulizers. These represent a low-cost, convenient, easily replaced, and well-tolerated option. Low-volume delivery is less effective than high-volume delivery at penetrating the paranasal sinuses.6 In CRS, low-volume nasal saline is recommended for high-volume intolerance or as an adjunct to high-volume therapy.6 The head back or lateral head low position are recommended for optimal low-volume irrigation penetration.6

Low-pressure, high-volume devices include NSI squeeze bottles and gravity-dependent irrigation pots. These products require users to prepare their own solutions and require regular maintenance and cleaning. The affordability and wide availability of NSI squeeze bottles make them an easily replaceable option. High-volume devices are associated with a greater incidence of discomfort, burning, and eustachian tube dysfunction as compared with low-volume devices.6 However, the combination of low cost, availability, tolerability, and superior distribution have made low-pressure, high-volume devices the “gold standard” for nasal saline delivery in CRS.9, 13

Examples of powered, high-pressure devices include the NeilMed® Sinugator® (NeilMed Pharmaceuticals, Santa Rosa, CA) and the Navage® (Rhinosystems, Inc, Brooklyn Heights, OH). These devices require additional expense compared with nonpowered high-volume devices, such as the NSI squeeze bottle. The Navage® requires users to purchase preformulated saline pods, which increases costs but results in added convenience and time-saving. Studies comparing these products to low-pressure, high-volume devices are limited. A 2017 cadaver study by Chen et al compared the NeilMed® Sinugator® to the classic NSI squeeze bottle (Table 2).10 It was shown that the squeeze bottle more effectively irrigated the maxillary, frontal, and sphenoid sinuses in both native and postoperative cavities.10

Examples of powered nasal nebulizers include the PARI Sinus™ (PARI Respiratory Equipment, Midlothian, VA) and the NasoNeb® (MedInvent, Inc, Parma, OH). As with powered high-pressure devices, these also necessitate expenses associated with durable medical equipment. Increased patient tolerance and improved mucosal coating of solution are the advertised benefits of these devices. A 2011 cadaver study by Manes et al evaluated the solution delivery of the NasoNeb® in native and postoperative cavities (Table 2).11 The authors determined the powered nasal nebulizer was effective at delivering solution to the middle meatus in native cavities, to the ethmoid and maxillary sinus after standard FESS, and to the frontal sinus after an extended modified Lothrop procedure.11 Further study and increased patient and provider experience will determine if powered high-pressure devices and powered nasal nebulizers warrant their increased costs.

Nasal saline composition

The composition of nasal saline is influenced by sodium chloride tonicity, added minerals, added oligo-elements, and temperature. Other adjunctive additives (steroids, antibiotics, saccharides, and surfactants) are beyond the scope of this review. However, it should be recognized that NSI is an important delivery vehicle for adjunctive additives, particularly off-label, high-dose topical steroids. Laboratory and clinical studies have focused on determining the most beneficial nasal saline composition. Basic science findings suggest hypertonic saline (HS; >0.9%) is more effective at decreasing intranasal mucosal edema and increasing ciliary beat frequency.14 However, clinical studies showing a clear patient benefit to using HS over isotonic saline (IS; 0.9%) in CRS or postoperative FESS patients are limited.3 In addition, HS is associated with greater patient discomfort and intolerance.15

In 2016, an in-vitro study by Bonnomet et al showed nondilute IS seawater solution more effectively improved ciliary beat frequency and wound repair speed when compared with dilute IS seawater and regular IS (Table 3).16 In addition, regular IS had a negative effect on epithelial cell function.16 A 2015 study by Woods et al compared the effect of low-salt solution, IS, and HS on the antimicrobial activity of nasal secretions (Table 3).17 The investigators determined that IS caused a greater decrease in the antimicrobial activity of nasal secretions when compared with low-salt solution and HS.17 The application of these findings into clinically meaningful conclusions has yet to be determined.

Table 3. Literature on nasal saline composition

• CBF = ciliary beat frequency; DB-RCT = double-blind, randomized, controlled trial; HRQL = health-related quality of life; HS = hypertonic solution; IS = isotonic solution; LR = lactated Ringer solution; RCT = randomized, controlled trial; WRS = wound repair speed.

A 2014 double-blind, randomized, controlled trial by Low et al compared the use of IS, HS, and lactated Ringer solution after FESS (Table 3).18 The authors observed a significant improvement in 6-week symptom scores and 1-week disease-specific health-related quality of life (HRQL) scores with lactated Ringer solution when compared with IS and HS.18 In a 2018 study, Nimsakul et al assessed the impact of NSI temperature on mucociliary clearance and nasal patency using saccharin transit time and peak nasal inspiratory flow (Table 3).19 No additional benefit was found on heating the solution.19 A 2018 systematic review and metaanalysis by Kanjanawasee et al compared HS with IS in patients with all types of sinonasal disorders, including postoperative patients (Table 3).15 In the report, the inclusion criteria were less stringent than in the 2016 Cochrane Review.15 The authors concluded that HS resulted in significantly greater symptom improvement, but no significant improvement in disease-specific HRQL.15 The improvement was more pronounced in allergic rhinitis patients.15 HS was associated with a higher incidence of minor side effects (9.7% vs 3.9%), including nasal burning, irritation, and epistaxis.15 Collectively, the current evidence does not allow for any definitive conclusions or recommendations regarding ideal saline composition.

Hygiene

NSI hygiene is an important topic that has occasionally been the focus of national attention. Official US Centers for Disease and Prevention (CDC) guidelines recommend using boiled water that has cooled (boiled for at least 1 minute or 3 minutes at an elevation of >6500 feet), microfiltered water (<1 μm pore), or bottled (distilled or sterile) water. In rare cases, NSI has been associated with primary amebic meningoencephalitis (PAM), which is most commonly caused by nasal exposure to Naegleria fowleri, a thermophilic ameba typically found in warm fresh water.20, 21 Young males with recent fresh water exposure in warm climate geography seem to be most at risk.21 After entering the nasal cavity, these ameba can travel along olfactory fibers to gain intracranial access.21 Neurologic symptoms typically develop within 7 days of exposure and the condition is usually rapidly fatal (within 5 days) after clinical presentation.21

The first 2 reported cases of PAM associated with NSI occurred in Louisiana in 2011 and were associated with potentially contaminated tap water.21 In both cases, the patients had no recent freshwater exposure and both had used a gravity-dependent irrigation pot with treated city tap water.21 Further investigation found N fowleri in the home water supply but did not find the ameba in the city tap water facilities or the patient irrigation pots.21

The most recent case of PAM related to NSI occurred in 2018 in the state of Washington.20 The causative ameba in this case was Balamuthia mandrillaris, which has a more indolent course than N fowleri.20 The patient used tap water filtered with a Brita water purifier (Brita LP, Oakland CA),20 which does not meet microfiltration requirements specified in the CDC guidelines. The patient developed a nonhealing superficial nasal rash approximately 1 month after starting the irrigations.20 Approximately 1 year later the patient presented with focal seizures20 and, after 4 weeks of medical care, her condition deteriorated and care was withdrawn.20 Final CDC testing confirmed that B mandrillaris was the causative agent for her nasal skin and brain lesions. No water source, home water, or squeeze-bottle testing was performed in this case.20 The northern geographic presentation of this case is atypical for PAM, which is associated with warmer weather climates. The significance of this is unknown.

Despite CDC and manufacturer recommendations, approximately 48% of patients report using tap water for their NSI.22 Studies have shown that device contamination occurs frequently, even with appropriate saline preparation and device maintenance.23 The clinical implications of irrigation bottle contamination is unknown. A 2016 study by Hauser et al collected samples from irrigation water (including tap water), rinse bottles, and the postoperative ethmoid cavities of 13 CRS patients.24 The microbiomes of each sample were analyzed and a close correlation between the microbiome of irrigation water and irrigation bottles was ultimately identified.24 In contrast, sinus cavity microbiomes did not correlate with the microbiomes found in irrigation water and irrigation bottles.24 No difference was found in the sinus cavity microbiome of sterile water users and tap water users.24 Ultimately, the study suggested that irrigation does not play a significant role in bacterial community structure in the postoperative paranasal sinuses.24

Based on current experience, the risk of NSI contamination does not outweigh the benefits of this treatment. The risk of bacterial and ameba contamination should be explained to patients and patients should be educated with regard to proper hygiene. NSI should incorporate water that meets CDC guidelines. Ultraviolet light water purification is a potentially more convenient and cost-effective method of water sterilization that is not part of the current CDC guidelines.25 Prepared solutions should be refrigerated and should not be stored for >7 days.26 Devices should be sterilized after every use and replaced every 3 months or according to manufacturer guidelines.23

Conclusion

NSI will continue to play an integral role in the treatment of CRS in the medical and postoperative setting. More evidence is required to determine definitively the efficacy of this treatment. IS delivered through a high-volume, low-pressure device continues to be the most common method of administration. Further high-quality comparative studies are required to determine if powered devices and HS offer an advantage over high-volume IS. Despite a lack of correlation between device contamination and clinical implications, contamination should be avoided and providers should thoroughly educate patients on NSI hygiene recommendations.