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December 15, 2017

Is 1 Liter of Nasal Fluid Produced a Day Truly Normal?

Ask any ENT how much nasal drainage is normally produced by a healthy human nose every day and you will be told 1 liter. But that's not what this blog article is about. Rather, HOW was this amount determined? What is the research behind this volume? The answer is surprisingly difficult to find and still up in the air... If any readers can do some sleuthing beyond what I report below, I would be much appreciative!

The vast majority of references found on simple google searching are quotes from ENT's interviewed for a magazine or newspaper article.

On deeper searching, 1 liter of normal nasal drainage can be found mentioned in research articles or medical texts, but still no explanation on how this volume was determined.

• "Approximately 1 liter of fluid is produced by nasal epithelium each day." [Medical Textbook, page 120]

• "A rough calculation of the daily volume of secretion and transudate from the nose is 1000 cc." [Research paper, page 126]

• "Mucociliary clearance is defined as cleaning of upper and lower airway by interaction of nasal mucus (about 200 g or 2 litre/day produced by the respiratory mucosa)" [Research paper, reference #36]

• I was able to find actual research describing methods to determine nasal secretion volume in animal studies. Here's one on guinea pigs.

• Using similar methods in animals, here's a research paper that described inserting filter paper into the nasal cavity of people and weighing how much secretions were absorbed after a period of time, but such information may not be entirely accurate due to nasal irritation from the filter paper itself.

• Here's another research paper describing a method of measuring nasal fluid by the urea concentration present.

In researching this topic, as an aside, nasal secretions are thought to be produced by mucous glands in the nasal lining and NOT from transudate directly from the blood vessels. [link]

Why is this Important?

One of the most common complaints people have when seeing a doctor is post-nasal drip or post-nasal drainage.

Typically such an abnormal sensation is NOT attributable to actual increase in nasal fluid volume, but rather changes in consistency and/or protein concentration along with environmental factors related to humidity and temperature.

However, if the underlying facts related to normal nasal fluid volume is incorrect, it does bring into question whether current treatment strategies is not ideal or at worst, frankly inaccurate.


Thus far, I have been stumped regarding where exactly the claim that a normal human nose produces 1 liter of fluid.

If any reader can shed light on this claim, that would be wonderful! Please report your findings below under the comment section.

Ideally, the information I am most interested in is the original source reference as well as the methodology used to determine the nasal fluid volume.

Nasal anatomy, physiology, and function. J ALLERGY CLIN IMMUNOL 72:123-128, 1983

Bacteriology of Humans: An Ecological Perspective. By Michael Wilson. John Wiley & Sons, Jan 26, 2009 - Science - 360 pages

A new method of the measurement of nasal secretion in guinea pigs. Int Arch Allergy Appl Immunol. 1991;95(1):29-34.

The Source of Nasal Secretion in the Normal Condition: Fluorescein Tests. Acta Oto-Larnyngologica. 1949;37:446-50.

Physiology and pathophysiology of respiratory mucosa of the nose and the paranasal sinuses. GMS Curr Top Otorhinolaryngol Head Neck Surg. 2010; 9: Doc07. Published online 2011 Apr 27. doi: 10.3205/cto000071

A standardized filter paper technique for assessing nasal secretory activity. Clinical Allergy, 1981, Volume 11, pages 287-292

Estimation of nasal epithelial lining fluid using urea as a marker. J ALLERGY CLIN IMWJNOL 1993;92:457-65.)

Allergologie-Handbuch: Grundlagen und klinische Praxis. Stuttgart: Schattauer; 2006.

December 08, 2017

Steps a Patient with Chronic Sinusitis Goes Thru

For the vast majority of patients with sinus infections, a trip to the primary care doctor's office and a prescription for antibiotics is all that is required. However, for the unfortunate few, several courses of oral antibiotics do not seem to help as much as it should.

In such cases, these patients eventually end up at an ENT office for further evaluation and management.

ASSUMING the patient has bona fide chronic or recurrent sinus infections and not some other medical problem confused for a sinus infection such as trigeminal migraines, these are the typical steps such patients go through in order to address their sinusitis. Keep in mind that some of these steps may be flipped or merged depending on an individual's unique clinical situation.

Step 1:
Endoscopic evaluation of the nasal cavity and if possible, the sinuses. If purulent drainage seen, culture are obtained in order to identify the organism and determine what antibiotics will work best to kill it (known as C&S). More oral antibiotics along with steroids typically prescribed at this stage. Nasal flushes with xlear or chitorhino can be tried especially if plain saline sinus flushes not helpful.

Step 2:
If not already done, allergy testing to evaluate for any allergic triggers that could be contributing or even driving the sinus infections. If allergies present, aggressive allergy medical management is started including medications and allergy shots.

Immunologic testing is also often performed in order to determine if there is some sort of immunodeficiency resulting in the body being unable to fight off infections as well as it should. Such immunologic testing typically evaluates for immunoglobulin (Ig) levels. More rarely, testing may include cellular immune functionality (lymphocytes, B cell memory, etc). If any immunologic dysfunction present, referral to immunology specialist is made.

Step 3:
CT Sinus scan to evaluate the extent of the sinus disease.

Step 4:
If medical management not working, sinus surgery is performed. Intra-operative cultures are obtained.

Step 5:
If sinus infections persist in spite of sinus surgery, more aggressive antibiotic treatment is performed via:

1) Adding antibiotics to the saltwater which is than flushed into the nose twice a day.
2) Injecting a thick gel impregnated with antibiotics and steroids into the sinus cavity filling it up. This will stick around for 2-4 weeks.

Step 6:
Potentially start a workup for potential autoimmune issues that may be contributing to the sinus infections (ie, Wegener's Disease, Churg-Strauss Syndrome, etc).

Step 7:
Ultimately, manage the sinus infections as a chronic illness, just like hypertension or diabetes.

December 03, 2017

Types of Medical Animations and Cost Implications

I've received numerous inquiries from physicians over the years regarding my experiences with medical animation development and cost given I've produced close to 30 animations thus far. Rather than going over the same materials each time I get a new inquiry, I wrote this blog article that addresses many of the questions I get.


There are essentially 4 types animations currently out there. There are both strengths and weaknesses for each animation type, but for the individual who will be paying for everything, cost is the main differentiator.

In parenthesis, I have included the average cost that an individual will typically be quoted... but towards the end of this article, I will explain how this cost can be dramatically reduced.

Realistic 3D Animation - VERY Expensive ($5000 - $10,000+ per minute)

This type of animation provides the wow factor and is akin to the CGI you would see in a hollywood blockbuster movie. Of course, you also pay orders of magnitude more. The rhinoplasty animation below is an example of 3D animation. Note that perspective is maintained even through different camera angles as well as realism of surface textures and appearances.

Semi-Realistic 3D Animation - Expensive (~$5000 per minute)

This type of animation is still 3D, but realism is sacrificed in order to save on cost.

2D Animation - Less Expensive (~$1000 per minute)

Note that the animation is much more cartoonish in appearance. Also note that only a single camera angle is used at all times.

Whiteboard Animation (aka, Explainer Videos) - Least Expensive (~$500 per minute)

Typically, animation is in black and white, though elements of color can be added. Movement is also limited in nature.


Although others may follow a different plan, the steps that I take to make the best possible animation with the least amount of money are as follows.

1. Create a VERY detailed storyboard. The storyboard is basically making a cartoon that describes what the scene will look like, lighting, camera angle, camera zoom, and duration every single moment of the imagined animation from start to finish. For example,

"At 0 seconds, start out showing the front of a woman's face filling the screen. The background is a light grey. Lighting is diffuse and even. Over the next 5 seconds, slowly zoom into the woman's face such that the nose fills 75% of the screen. Once zoomed in, over the next 3 seconds, turn the camera angle 30 degrees to the left such that the side of the nose is centered."

The storyboard should include reference illustrations and videos to try and explain to illustrator what you envision. I typically get such reference images from Google Images, YouTube, and textbooks.

Cut out anything that is not necessary since every additional second/minute adds significantly to the cost.

2. Based on the storyboard, decide which type of animation style would work best at conveying the information you have. Although 3D animation for everything would be great if you have an unlimited budget, it is not always technically necessary. For example, I decided on 2D animation to describe how allergy vials are made above as 3D really would not have added to the information I was trying to convey. However, for the rhinoplasty video, 3D was extremely important as nasal appearance in all dimensions is something patients like to see as it may be hard to visualize such information in 2D only.

3. Get quotes from animators based on your storyboard. I typically get quotes from which is a freelance marketplace where bids can be obtained from all over the world. I hate to say this, but typically animation development is much cheaper in places like India. Also, I have found that individual freelance animators typically cost less than animation companies.

How much less? Often up to 50% less. That's not to say to never use a United States based animator (I have...), but just be aware that similar quality animation can be created elsewhere in the world typically for less.

Once you pick an animator, work can begin, but here's a few things to keep in mind to prevent surprise expenses and minimize annoying your animator.

• ALWAYS respond promptly to questions. The animator can not continue working on the animation without constant feedback and approval to go on to the next step in the storyboard. If it takes 24 hours for you to respond, the animator will have to wait 24 hours before continuing to work on your animation. This wastes their time.
• Have the animator create still shots of storyboard scenes first for your approval before they animate anything.
• When animation finally created, keep the amount of detail to a minimum initially. Make sure that the camera angles, sequence of events, zoom, etc are all looking good first. Once draft animation approved, final animation with full rendering of textures and details can be produced as the last step. Why? Because it takes time for a computer to create the movie with full detail whereas "draft" animations can be produced quickly.
• Try to avoid requesting changes AFTER you have already approved something. The biggest faux pas is to request a change after you have already approved of an animation sequence. Why? Because even a small insignificant change may require the animator HOURS of work to implement. To use an analogy, it's like a homeowner asking a builder to make the basement slightly bigger after the first and second floors have already been built. Or deciding to change the color of a yarn pattern after the sweater has already been knit.

If you request changes after initially approving something, you might be charged extra for additional work that needs to be redone. Most animators will forgive one or two such changes, but WILL charge extra if you keep making changes beyond that.

Typically, the animator is paid in thirds: 1/3 of the project cost immediately or after stills approved; 1/3 after first animation draft; and 1/3 after project completion.


Once an animator has created something for you... additional animations based on the same model can be made for much less. For example, using the same nasal hump rhinoplasty model above, I was able to create a different rhinoplasty video shown below for significantly less.

I also would not worry about how fast or slow the animation is in certain scenes. That's something you can easily change in any video editing program like iMovie or Final Cut Pro X (which I use). No need to pay an animator to do this. Needless to say, you can save money by doing things yourself where you can. This includes narration, background music, title screens, credit screens, etc.

Just FYI, copyright free background music and sound effects are available through YouTube's Creative Studio.

I personally ALWAYS credit the animator in videos I publish because I feel it is the right thing to do. But when negotiating cost with an animator, do NOT bother to ask for a discount if you provide such credit. Providing credit is not a particularly big carrot for animators because there's no guarantee that your video will actually be popular enough to warrant giving you a discount. Perhaps if you have already established a track record for creating popular videos, the animator might provide a small discount, but don't count on it.

December 02, 2017

Foster Half-Somersault Maneuver to Treat BPPV Video

Traditionally, posterior canal BPPV is treated using a maneuver called the Epley (shown below). With a nearly 80%+ success rate in "curing" vertigo due to posterior canal BPPV, this has been the mainstay of treatment since the 1980s.

Although the Epley maneuver is easy to perform, certain steps do require laying down with the head hyper-extended. This position is not easily feasible if a vertigo attack occurs at work or in public.

In such inconvenient situations, the Foster Half-Somersault maneuver shown above may be not only more feasible, but also easier to perform for some patients. Published in 2012 by Dr. Carol Foster in Denver, CO, this maneuver is comparable in success rates to the Epley in the treatment of posterior canal BPPV.

Steps to the Half-Somersault are as follows:

1) While kneeling, the head is quickly tipped upward and back.
2) The somersault position is assumed, with the chin tucked as far as possible toward the knee.
3) The head is turned about 45° toward the right shoulder, to face the right elbow (if the right ear is affected).
4) Maintaining the head at 45°, the head is raised to back/shoulder level.
5) Maintaining the head at 45°, the head is raised to the fully upright position.

Read more about BPPV vertigo here.

November 26, 2017

Tonsillectomy Associated with Increased Pregnancy / Fertility Rates

Image courtesy of nenetus at
A reader pointed this interesting research article from the United Kingdom that suggests females who have undergone tonsillectomy and/or appendectomy had increased fertility rates compared to women who have had neither surgeries. Fertility in this study was measured by time to pregnancy after surgery.

The results reported are as follows:

• During a mean follow-up of about 15 years after surgery, 53.4% of women who underwent tonsillectomy only became pregnant. 59.7% of women who underwent both appendectomy and tonsillectomy became pregnant. These numbers are significantly higher than the 43.7% pregnancy rate in an age-matched cohort of women who had neither surgeries.
• Time to pregnancy was also shorter for women who underwent tonsillectomy compared to women who did not.
• Age at first birth was also lower for women who underwent tonsillectomy (25.8 years control vs 24.5 years for tonsillectomy group).

Reasons why this association exists is speculative, but is thought to be related to systemic inflammation that may be present with chronic or recurrent tonsil infections.

Removal of the inflamed tonsils is thought to reduce overall systemic inflammation that may improve the overall health of the uterus and embryo resulting in a higher chance of a successful pregnancy. When inflammation due to tonsils becomes too excessive or chronic or consists of specific mediators in high enough concentrations, it might cause degeneration of the embryo and impaired implantation.

Inflammatory conditions adversely affecting fertility has been found to be true with other medical illnesses including inflammatory bowel disease and rheumatoid arthritis.

The researchers concluded by stating that guidelines should be adjusted such that young women suffering from recurrent tonsillitis should have a lower threshold for tonsillectomy.

Association between prior appendectomy and/or tonsillectomy in women and subsequent pregnancy rate: a cohort study. Fertility and Sterility. Volume 106, Issue 5, Pages 1150–1156. October 2016.

November 19, 2017

How to do Home Balance Exercises for Treating Dizziness VIDEO

The home balance exercises described in the video may be helpful to resolve dizziness due to vestibular dysfunction that is NOT due to BPPV or Meniere's Disease which are treated differently. Vestibular dysfunction amenable to a home exercise regimen is typically determined based on VNG or ENG testing. Such exercises are helpful in select patients as it slowly challenges the inner ear balance system in such a way to make it work better. The analogy would be a young gymnast doing repetitive exercises to make their sense of balance supernormal in order perform amazing feats on the balance beam or a ballerina doing similar exercises to maintain perfect balance even though they are dancing on the tip of one toe. Needless to say, there is no "pill" that makes balance improve quickly. Drugs like meclizine may only temporarily help, but often makes balance WORSE in the long run. Read more about how drugs like meclizine work.

The human balance system is composed of 3 different systems working together to allow for dizzy-free movement.

• The eyes provide visual cues
• The inner ear balance system provides gyroscopic information
• Proprioception provides sense of position in space based on information provided from the muscles, tendons, and joints

What these exercises try to accomplish is to challenge and thereby improve the inner ear balance system in a graduated fashion by slowly taking away balance information provided by the eyes (by closing them) as well as proprioception (walking heel-to-toe). Although the first few exercises may be overly easy and simplistic, balance may be quite challenging by the end (exercise #10).

Each exercise should be performed 20 times, twice a day.

Keep in mind that such home exercises will NOT help with dizziness due to BPPV as well as Meniere's Disease. It only helps with stable vestibular dysfunction. To use an orthopedic analogy, BPPV is like a dislocated shoulder for which a single set of highly specific movements can "cure" the problem. Meniere's disease is analogous to severe muscle cramps (periods of absolute normalcy followed by extreme abnormality). Stable vestibular dysfunction is analagous to weak muscles for which working out in the gym regularly is required to make them stronger.

If you are not quite sure what type of dizziness you have, click here to try and figure it out.

The video below explains how the inner ear balance system works:

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