Helping Clean the Nose: The Solution to Pollution is Dilution.

First some background    

    The idea of cleaning the body is relatively new in the history of mankind. Until water supplies were made safe in the last century water was known to be the carrier of deadly diseases like cholera. Our current ideas about washing began with Ignaz Semmelweis.

    In the 1840’s  Semmelweis found out that women in labor were less likely to get "childbed fever" if the doctors washed their hands in a solution of chloride and lime before they examined the women. Childbed fever, or Puerperal sepsis, was caused by bacteria that the doctors carried on their hands from the dissecting room to their patients in labor. Many people died from infections in that day and the doctors picked up the bacteria as they were dissecting – without gloves – and introduced them to the women they then examined.  Fifteen percent of women giving birth in hospitals were dying because of these infections. The hand-washing worked in Vienna, but Semmelweis could not persuade his colleagues elsewhere that they were causing their patients illness. Twenty years later Pasteur, and his germ theory, showed that Semmelweis was right, but even then most physicians would not even accept Pasteur’s findings. Hand-washing, and what doctors call aseptic technique, was not accepted until the 1880’s. Even the stubborn could not refute what they were seeing under the lenses of their ever more common microscopes. The CDC tells us "Hand-washing is the single most important means of preventing the spread of infection." It is easy to see the benefit of hand washing before surgery or any hands-on-exam that may introduce bacteria into the body. It is harder to see the benefit of regular hand washing in the absence of this invasive exposure – but we invade ourselves. The bacteria that make us sick don’t get into our bodies through our hands, but we put our hands to our own faces and the bacteria invade through eyes, nose and to a lesser extent the mouth. The unstated purpose of hand washing is to protect the face and especially the nose, because that is where most infections enter. An excellent review of the history of hand-washing is found at the web site for access excellence. 

    This web site also tells the story of some New York pediatricians who complained to the city's health board that the boards promotion and teaching of good hygiene, which included hand washing, to the city's mothers was adversely effecting their practices. A system that pays physicians, who are supposed to keep us well, only when we are sick can, at times, lead to problems – and some of them may still be with us. For more about this see the story of Sara Baker at commonsensemedicine.org

How about washing the nose?

• Saline nasal sprays have been available for a long time. 
  • They actually became popular to counter the dryness that went with the use of antihistamines and decongestants. 
  • Regular use decreases inflammatory markers in the nose and improves quality of life. 
  • But while they loosen the mucus they don't help to clean the cells under the mucus.
• Hypertonic solutions using saline are available. 
  • These solutions are more concentrated than the fluid in the tissues of the nose. 
  • They speed the clearance of the nasal mucus by pulling fluid from the cells to help with the washing. 
  • To learn more about this commercially available solution this link will take you to their web site.
  • Hypertonic saline is easy to make and expensive to buy. 
  • The problem with making it is that many people think that more is better. This is not the case with saline. 
  • Isotonic saline is made by adding a half teaspoon of salt to a cup of water. 
    • This concentration slows the cilia. 
    • A little more than three teaspoons of salt in the same amount of water paralyses the cilia temporarily, and twice that paralyses them permanently.
• Many doctors recommend regular irrigation of the nose with lots of these fluids. 
• Irrigation is more likely to remove the mucus than sprays, but the mucus is the stuff that catches the bacteria—some of it is good. 
• If you could look into the back of the nose with a microscope you would see the bacteria in the mucus, not on the cells. 
• Removing the mucus allows the bacteria to attach to the cells where they can cause infection.
• Another problem with saline, especially hypertonic saline, is that the body's own antibacterial defenses, that are present in the fluids coating the airways, underneath the mucus (they're called defensins), work better when the saline concentration is lower. This concept is covered in the section on saline and defensins.
• It does this because the small xylitol molecule acts osmotically to pull fluid, water, to itself. This water reduces the saline concentration allowing the defensins to be more effective.
• Hyperosmolar solutions have more small molecules like sugars or proteins in a solution than the body's fluid have. By osmosis they pull water into these hyperosmolar solutions. 
• When we breathe cold dry air the water in our nose evaporates to moisten the air and the solutions remaining become hyperosmolar. This stimulates more blood flow and our normal washing.
• Researchers at Johns Hopkins University duplicated this condition by putting a solution of mannitol in the nose that was about three times more concentrated than the fluids in the body. They found that when they put about a teaspoon of this solution into the nose and let it sit for only ten seconds that it does two things.

        (1)  It stimulates the release of histamine.

        (2) It pulls fluid from the tissues of the nose.

  In other words this hyperosmolar solution turns on the washing machine and makes it more effective by pulling the water from the tissues— more water is added for the washing. And it pulls this water from underneath the mucus in a way that is virtually identical to our own normal nasal cleaning—the fluid lifts the mucus up off the cilia. And the histamine helps this process.

      Xylitol is a sugar alcohol with  osmotic properties similar to mannitol. The osmolality of the xylitol in the spray I use is about 2 1/2 times the normal body osmolality—high enough to reproduce this effect.

     The Iowa researchers, mentioned earlier and covered in a different page,  used 5% (near normal osmolality) of xylitol in a nasal spray. They found several important benefits of xylitol:

• Regular use four times a day for four days  reduced bacterial colonization in the nose. 
• Xylitol is not absorbed by nasal cells so it stays in the mucus and ends up in the stomach when the mucus is swallowed. 
• Most bacteria cannot use xylitol for food so they can't grow as rapidly as they normally do.

These researchers referred to  the work of the Finns with xylitol, but gave little credit to the effects of xylitol on particular bacteria demonstrated by the Finnish studies. I believe these effects are very significant. 

Nasal-Xylitol Home

 

Laryngoscope 1999 Mar;109(3):396-9

Physiologic and hypertonic saline solutions impair ciliary activity in vitro.

Boek WM, Keles N, Graamans K, Huizing EH

Department of Otorhinolaryngology, University Hospital Utrecht, The Netherlands.

OBJECTIVE/HYPOTHESIS: Physiologic saline (NaCl 0.9%) is commonly used in treating acute and chronic rhinosinusitis. Moreover, physiologic saline is used as a control medium, vehicle, or solvent in studies on ciliary beat frequency (CBF). Hypertonic saline (NaCl 7% and 14.4%) has been applied in attempts to enhance mucociliary transport in patients with cystic fibrosis or asthma and in healthy subjects. Therefore the objective of this study is to document in vitro effects of saline solutions in different concentrations on CBF. STUDY DESIGN: Experimental, in vitro. METHODS: The effects on CBF of cryopreserved mucosa of the sphenoidal sinus was measured by a photoelectrical method. Initial frequencies, measured in Locke-Ringer's solution (LR), were compared with CBF after exposure to NaCl in concentrations of 0.9%, 7.0%, and 14.4% (w/v). RESULTS: NaCl 0.9% has a moderately negative effect on CBF. The 7% solution leads to a complete ciliostasis within 5 minutes, although this effect turns out to be reversible after rinsing with LR. A hypertonic solution of 14.4% has an irreversible ciliostatic effect. CONCLUSION: LR is an isotonic solution that has no effect on CBF. Therefore it is probable that this solution is more appropriate than saline for nasal irrigation and nebulization or antral lavage. Moreover, the results of this study suggest that mucolytic effects induced by hyperosmolarity should be attained preferably with hypertonic saline 7% in patients with cystic fibrosis or asthma. At this concentration, the ciliostatic effect is reversible, whereas irreversible changes are to be expected at higher concentrations.

PMID: 10089964

 

Proc Natl Acad Sci U S A 2000 Oct 10;97(21):11614-9

[A free full text of this article is available at www.ncbi.nlm.nih.gov:80/entrez/utils/fref.fcgi?http://www.pnas.org/cgi/pmidlookup?view=full&pmid=11027360]
The osmolyte xylitol reduces the salt concentration of airway surface liquid and may enhance bacterial killing.

Zabner J, Seiler MP, Launspach JL, Karp PH, Kearney WR, Look DC, Smith JJ, Welsh MJ

Howard Hughes Medical Institute, Departments of Internal Medicine, Pediatrics, and Physiology and Biophysics, and Nuclear Magnetic Resonance Facility, University of Iowa College of Medicine, Iowa City, IA 52242, USA. joseph-zabner@uiowa.edu

The thin layer of airway surface liquid (ASL) contains antimicrobial substances that kill the small numbers of bacteria that are constantly being deposited in the lungs. An increase in ASL salt concentration inhibits the activity of airway antimicrobial factors and may partially explain the pathogenesis of cystic fibrosis (CF). We tested the hypothesis that an osmolyte with a low transepithelial permeability may lower the ASL salt concentration, thereby enhancing innate immunity. We found that the five-carbon sugar xylitol has a low transepithelial permeability, is poorly metabolized by several bacteria, and can lower the ASL salt concentration in both CF and non-CF airway epithelia in vitro. Furthermore, in a double-blind, randomized, crossover study, xylitol sprayed for 4 days into each nostril of normal volunteers significantly decreased the number of nasal coagulase-negative Staphylococcus compared with saline control. Xylitol may be of value in decreasing ASL salt concentration and enhancing the innate antimicrobial defense at the airway surface.

PMID: 11027360

 

Am Rev Respir Dis 1988 Mar;137(3):606-12

In vivo release of inflammatory mediators by hyperosmolar solutions.

Silber G, Proud D, Warner J, Naclerio R, Kagey-Sobotka A, Lichtenstein L, Eggleston P

Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.

Hyperosmolar environments induce histamine release from mast cells and basophils in vitro. To assess whether the same stimulus induces mediator release in vivo, 15 healthy human volunteers underwent nasal challenges with instilled solutions of differing osmolalities: lactated Ringer's solution (257 +/- 3 mOsm/kg), isosmolar mannitol (277 +/- 6 mOsm/kg), and hyperosmolar mannitol (869 +/- 8 mOsm/kg). The effect of these challenges on the volume, osmolality, and inflammatory mediator content of subsequent 5-ml isosmolar lavages was determined. The volumes of lavages returned after hyperosmolar challenges were significantly greater than those after isosmolar challenges (5.5 +/- 0.2 ml versus 4.2 +/- 0.1 ml; p less than 0.01) and these lavage solutions had higher osmolalities. Even when corrected for increased volumes, the lavages after hyperosmolar challenges contained significantly higher quantities of inflammatory mediators such as histamine (29.0 versus 10.1 ng; p less than 0.01), TAME-esterase activity (32.7 versus 11.1 cpm x 10(-3); p less than 0.01), and immunoreactive leukotrienes (9.9 versus 3.4 ng; p less than 0.01). The changes in mediators were dose dependent in that incremental increase in challenge osmolality were associated with incremental increases in histamine release. Therefore, when exposed to hyperosmolar stimuli in vivo, the nasal respiratory airway releases inflammatory mediators and fluid rapidly shifts into the airway lumen. It has been suggested that the mediator release observed on breathing cold and dry air is due to increased osmolality of airway secretions; the present data confirm that osmotic variations at the airway surface can provide an adequate stimulus for cell activation.

PMID: 2449834