Upper Airway Resistance

Effect of nasal or oral breathing route on upper airway resistance during sleep

M.F. Fitzpatrick1, H. McLean1, A.M. Urton1, A. Tan2, D. O'Donnell1 and H.S. Driver3
1 Depts of Medicine, and 2 Otolaryngology, Queen's University, and 3 Kingston General Hospital, Kingston, Ontario, Canada

CORRESPONDENCE: M. Fitzpatrick, Division of Respiratory and Critical Care Medicine, Queen's University, 102 Stuart Street, Kingston, Ontario, K7L 2V6, Canada. Fax: 1 6135491459. E-mail: mf19@post.queensu.ca

Keywords: breathing route, mouth breathing, sleep apnoea, upper airway resistance

Received: April 30, 2003
Accepted June 16, 2003

This study was funded by grants from the William M. Spear Foundation, Queen's University and the Physicians' Service Incorporated Foundation, Ontario.

Healthy subjects with normal nasal resistance breathe almost exclusively through the nose during sleep. This study tested the hypothesis that a mechanical advantage might explain this preponderance of nasal over oral breathing during sleep.

A randomised, single-blind, crossover design was used to compare upper airway resistance during sleep in the nasal and oral breathing conditions in 12 (seven male) healthy subjects with normal nasal resistance, aged 30±4 (mean±sem) yrs, and with a body mass index of 23±1 kg·m2.

During wakefulness, upper airway resistance was similar between the oral and nasal breathing routes. However, during sleep (supine, stage two) upper airway resistance was much higher while breathing orally (median 12.4 cmH2O·L–1·s–1, range 4.5–40.2) than nasally (5.2 cmH2O·L–1·s–1, 1.7–10.. In addition, obstructive (but not central) apnoeas and hypopnoeas were profoundly more frequent when breathing orally (apnoea-hypopnoea index 43±6) than nasally (1.5±0.5).

Upper airway resistance during sleep and the propensity to obstructive sleep apnoea are significantly lower while breathing nasally rather than orally. This mechanical advantage may explain the preponderance of nasal breathing during sleep in normal subjects.

for the full article:
http://www.erj.ersjournals.com/cgi/cont ... t/22/5/827

Thanks for posting that.

I'm glad to see that someone confirmed MY theory as it applies to me and my sleeping/breathing.

Den

Useful post. More motiviation for me to get more things looked at.

I've always said to myself 'you got to be kidding' when in gym class they told us to breath through our nose as much as possible. If I relied on nose breathing for any activity but sitting, I'd fall over unconscious. Even just sitting I can't get by long without some additional mouth breathing eventually.

Time for a visit to an ENT.

Probably too late to get anything I find addressed this year. Chance, I may not have insurance next year. Bummer.

And to further add to the study mentioned by Snoredog:

Am J Respir Crit Care Med. 1996 Jan;153(1):255-9.Links
Effects of mouth opening on upper airway collapsibility in normal sleeping subjects.Meurice JC, Marc I, Carrier G, Sériès F.
Unité de recherche, Hôpital Laval, Université Laval Québec, Sainte-Foy, Canada.

We investigated the influence of mouth opening on upper airway (UA) collapsibility in six healthy sleeping volunteers. UA collapsibility was measured during continuous negative airway pressure trials that consisted of the progressive decrease in pressure in a nasal mask, with simultaneous recording of esophageal pressure and instantaneous flow. Measurements were made under two experimental conditions: mouth closed (MC), and mouth open (MO). Cephalometric measurements were obtained with subjects awake in the same position for both experimental conditions. UA critical pressure (Pcrit) was derived from the relationship between the breath-by-breath values of the maximal inspiratory airflow and the corresponding mask pressure. Pcrit was significantly less negative during MO than during MC (MO, -12.7 +/- 4.8 cm H2O; MC, -16.4 +/- 6 cm H2O, mean +/- SD; p = 0.03). Mouth opening was associated with a significant increase in the total respiratory resistance (MO, 3.8 +/- 1.6 cm H2O/ml/s; MC, 3.0 +/- 1.6 cm H2O/ml/s-1, p = 0.03). Besides an increase in the distance between the teeth and a reduction in the distance between the hyoid bone and the mandible, no significant changes in cephalometric parameters were found between MO and MC. We conclude that mouth opening increases UA collapsibility during sleep and that mouth opening may contribute to the occurrence of sleep-related breathing abnormalities.

Snoredog, Good info - very interesting. Thanks.

DSM

Very interesting indeed. Some actual numbers to get some sense of the magnitudes.

Snoredog, Thanks for the citation.

OT, but this caught my eye:

Subjects wore a soft neck collar to stabilise neck position
during sleep, as neck position can influence upper airway
resistance.

I can offer some personal empirical confirmation on the neck-collar idea. Since I switched to using one of those neck-ring style travel pillows (turned sideways or backwards to provide a ledge for my chin) in lieu of a chinstrap, my AHI finally consistently dropped below 3. I lay the upper part of my head on a regular pillow so that pressure is evenly balanced between neck, shoulders, and head. My ears don't like to be squished so another benefit for me has been reduced pressure on the ears.

split_city wrote:And to further add to the study mentioned by Snoredog:

Am J Respir Crit Care Med. 1996 Jan;153(1):255-9.Links
Effects of mouth opening on upper airway collapsibility in normal sleeping subjects.Meurice JC, Marc I, Carrier G, Sériès F.
Unité de recherche, Hôpital Laval, Université Laval Québec, Sainte-Foy, Canada.
<snip> We conclude that mouth opening increases UA collapsibility during sleep and that mouth opening may contribute to the occurrence of sleep-related breathing abnormalities.

This says "mouth opening" so I'm assuming they mean your mouth is open but you're not breathing through it? I wake up a lot with my mouth open (sometimes slightly, sometimes a lot), but my tongue is planted on the roof of my mouth and I'm breathing through my nose. That might not be what was going on all night, but at least when I wake up it is that way often. (I had more UARS on my sleep study than anything else.)

I tend to breathe through my mouth a lot, too (in addition to what I said in the above paragraph). My AHI numbers don't seem to change much due to that, but the snoring numbers have nights when they're WAY up there (30+), and this might be the reason.

Raj wrote:I can offer some personal empirical confirmation on the neck-collar idea. Since I switched to using one of those neck-ring style travel pillows (turned sideways or backwards to provide a ledge for my chin) in lieu of a chinstrap, my AHI finally consistently dropped below 3. I lay the upper part of my head on a regular pillow so that pressure is evenly balanced between neck, shoulders, and head. My ears don't like to be squished so another benefit for me has been reduced pressure on the ears.

Thanks Raj. I wonder why the market is not pushing various neck-collars like it does specialty pillows and oral devices?

I asked my sleep doctor about the neck collars. She said you should sleep in a position equal to a good posture position when standing. The back of the neck should be straight and the chin should be at the mid or "good posture" level, neither too high nor too low. Her opinion was if you can consistently sleep like this then a neck collar is an unnecessary aggravation. What do you think?

rooster wrote:

Raj wrote:I can offer some personal empirical confirmation on the neck-collar idea. Since I switched to using one of those neck-ring style travel pillows (turned sideways or backwards to provide a ledge for my chin) in lieu of a chinstrap, my AHI finally consistently dropped below 3. I lay the upper part of my head on a regular pillow so that pressure is evenly balanced between neck, shoulders, and head. My ears don't like to be squished so another benefit for me has been reduced pressure on the ears.

Thanks Raj. I wonder why the market is not pushing various neck-collars like it does specialty pillows and oral devices?

I asked my sleep doctor about the neck collars. She said you should sleep in a position equal to a good posture position when standing. The back of the neck should be straight and the chin should be at the mid or "good posture" level, neither too high nor too low. Her opinion was if you can consistently sleep like this then a neck collar is an unnecessary aggravation. What do you think?

I THINK I get the same benefit from using the Chiroflow water-based pillow. With the proper amount of water, it keeps things (head/neck/spine) pretty much in alignment. And, my mask isn't being pushed off my face by the ends of the pillow as it would be by using a standard pillow with my head sinking into it.

Den

Rooster and Den, originally I bought the travel pillow to support my chin while sleeping (thus replacing the need for a chinstrap) and wasn't expecting the breathing benefit. I happen to have unusually broad shoulders for my height and have trouble maintaining the proper alignment on any kind of pillow and I've tried everything from water-filled to top-of-the-line Tempurpedic. With a pillow high enough to keep my head level, I tend to shift out of position while sleeping and wind up with my neck rather, um, scrunched to use the technical term. If you can sleep properly aligned I see no breathing benefit from using my kludge although it might be worth experimenting with for a few nights. Mine is a homedics memory-foam travel pillow with a fleece cover.

~Raj

WearyOne wrote:

split_city wrote:And to further add to the study mentioned by Snoredog:

Am J Respir Crit Care Med. 1996 Jan;153(1):255-9.Links
Effects of mouth opening on upper airway collapsibility in normal sleeping subjects.Meurice JC, Marc I, Carrier G, Sériès F.
Unité de recherche, Hôpital Laval, Université Laval Québec, Sainte-Foy, Canada.
<snip> We conclude that mouth opening increases UA collapsibility during sleep and that mouth opening may contribute to the occurrence of sleep-related breathing abnormalities.

This says "mouth opening" so I'm assuming they mean your mouth is open but you're not breathing through it?

Yep, that is correct.


Re neck position: There are a few studies showing the neck position has a significant impact on airway resistance/collapsibility. A study by a group in Perth, Australia, showed that airway collapsibility changed in the order of 5-10cmH20 between neck flexion (chin towards chest) to neck extension (chin away from chest) in anesthetized subjects.