Factors affecting upper airway resistance in conscious man.

Spann, R W; Hyatt, Robert E.

doi:10.1152/jappl.1971.31.5.708

Cited by 93 publications

(43 citation statements)

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“…The area of the pharyngeal opening was several times that of the relaxed larynx suggesting that the larynx was the main site of resistance; this conclusion was supported by the fact that measured 'laryngeal resistance' was about one tenth of total lung resistance. In man the resistance of the intact upper respiratory tract is about equal to total lung resistance (Ferris, Mead & Opie, 1964;Hyatt & Wilcox, 1961), and laryngeal resistance is about onethird of upper airway resistance (Spann & Hyatt, 1971 (Table 1) and of the pressure/flow curves for the innervated and denervated larynx (Fig. 2).…”

Section: Discussionmentioning

confidence: 99%

The effects of lung reflexes on laryngeal resistance and motoneurone discharge

Stránský¹,

Szereda-Przestaszewska²,

Widdicombe³

1973

The Journal of Physiology

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SUMMARY1. The reflex action of stimulation of alveolar J-receptors and of airway epithelial irritant receptors has been investigated on laryngeal resistance to airflow and on laryngeal motoneurone discharge in cats and rabbits.2. Resistance to airflow of the innervated larynx was measured (1) with the larynx isolated in situ with constant flow from the trachea to a pharyngeal opening; and (2) with the animal breathing through the larynx and the pharyngeal opening. With both methods resistance was determined from the relationship between translaryngeal pressure and airflow.3. In control conditions the laryngeal resistance was about one tenth of total lung resistance.4. i.v. injections of phenyl diguanide (to stimulate J-receptors) caused apnoea and complete closure of the larynx, followed by rapid shallow breathing with expiratory constrictions ofthe larynx. Expiratory laryngeal motoneurones were strongly stimulated.5. The laryngeal responses to phenyl diguanide were nearly abolished by bilateral vagotomy in the chest (below the origin of the recurrent laryngeal nerves), and were absent on injection of the drug into the left atrium; the motoneurone responses were abolished by vagotomy and lessened by paralysis and artificial ventilation.6. I.v. injections of histamine acid phosphate or inhalation of an aerosol of the drug in solution (to stimulate lung irritant receptors) caused tachypnoea and expiratory constrictions of the larynx, and increased discharges in expiratory laryngeal motoneurones.

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Section: Discussionmentioning

confidence: 99%

The effects of lung reflexes on laryngeal resistance and motoneurone discharge

Stránský¹,

Szereda-Przestaszewska²,

Widdicombe³

1973

The Journal of Physiology

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“…Air leaks and communication between the oral and nasal compartments of the facemask were meticulously excluded by regular testing throughout each test night, as per the authors normal routine [1]. Subjects wore a soft neck collar to stabilise neck position during sleep, as neck position can influence upper airway resistance [5][6][7].…”

Section: Methodsmentioning

confidence: 99%

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

Fitzpatrick¹,

McLean²,

Urton³

et al. 2003

Eur Respir J

213

132

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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?m 2 . 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 In a recent publication the authors described, for the first time, partitioning of inhaled ventilation between the nose and mouth during sleep in healthy subjects with normal nasal resistance [1]. The main finding of the latter study was that the oral fraction of inhaled ventilation during sleep was very small, averaging only 4% for the group of 10 subjects, and several subjects did not breathe through their mouth at all during sleep. Furthermore, the inhaled oral fraction did not change significantly between different non-rapid eye movement sleep stages or between rapid eye movement (REM) and non-REM sleep.The physiological explanation for the marked predominance of nasal ventilation over oral ventilation during sleep in normal subjects is unknown. Since total airway resistance while awake and breathing through the mouth is typically 2-4 cmH 2 O?L -1 ?s -1 [2] and the normal nasal resistance alone is of similar magnitude [3], it is not intuitively obvious why healthy subjects should choose to breathe almost exclusively through the nasal route during sleep. Specifically, there are no published measurements describing the effect of oral versus nasal breathing on upper airway resistance during sleep.It is important to understand the influence of the breathing route (oral or nasal) on upper airway resistance during sleep from the perspective of understanding normal respiratory physiology during sleep, but this information may also provide an insight into the relationship between the breathing route and upper airway obstruction during sleep. The authors hypothesised that the observed preponderance of nasal over oral ventilation in normal subjects during sleep would reflect a mechanical advantage of the nasal breathing route. To test this hypothesis, the authors compared upper airway resistance during nasal breathing and during oral breathing in healthy sleeping subjects with normal nasal resistance. Methods Study designA randomised, single blind, crossover study was conducted to compare upper airway resistance during sleep when nose breathing with that when mouth breathing. Subjects underwent a single overnight polysomnogram at Kingston General Hospital Sleep Laboratory, Ontario. The night was divided into two parts, oral breathing and nasal breathing, the order being randomised...

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“…They also outlined certain disadvantages related to the non-physiological nature of panting but felt these were likely to be of lesser importance. Measurements of laryngeal or upper airway resistance have usually shown a small reduction during panting (Hyatt & Wilcox, 1961;Ferris et al, 1964;Spann & Hyatt, 1971), presumably related to the increased size of the glottis (Stanescu et al, 1972;Baier, Wanner, Zarzecki & Sackner, 1977).…”

Section: Body Plethysmographymentioning

confidence: 99%

“…In normal subjects upper airway resistance falls slightly as respiratory frequency is increased (Spann & Hyatt, 1971) and as panting volume is reduced (Stanescu et al, 1972) the latter probably because of reduced turbulence. However, when panting was compared to quiet breathing in the body plethysmograph there was no difference in Raw in normal subjects ) though a small reduction (12%) was seen in patients with chronic bronchitis similar to that seen in a similar group of patients by Barter & Campbell (1973).…”

Section: Body Plethysmographymentioning

confidence: 99%