Chest
Volume 130, Issue 6, December 2006, Pages 1757-1764
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Original Research: Sleep Medicine
Relationship Between Upper Airway and Inspiratory Pump Muscle Force in Obstructive Sleep Apnea

https://doi.org/10.1378/chest.130.6.1757Get rights and content

Background

Upper airway (UA) patency during inspiration is determined by the balance between dilating forces generated by UA dilator muscle activity and collapsing forces related to the decreased intraluminal pressure that accompanies flow generated by inspiratory muscle activity. It is possible that the relative strengths of UA dilator and inspiratory pump muscles could be an important determinant of the susceptibility to UA collapse during sleep (ie, obstructive sleep apnea [OSA]).

Methods

Measurements of tongue protrusion (TP) force and maximum inspiratory pressure (Pimax) were obtained in 94 patients admitted for overnight polysomnography for suspected OSA, quantified by apnea-hypopnea index (AHI).

Results

There was a direct linear relationship between TP force and Pimax (r2 = 0.37, p < 0.001). A high ratio of TP force to Pimax (greater than group 90th percentile, 0.027 kg/cm H2O) appeared to protect against OSA, as moderate-to-severe OSA (AHI > 20/h) was not observed in any individual with a ratio above this threshold. AHI was not linearly related to TP force, Pimax, or the ratio of TP force to Pimax.

Conclusions

UA muscle strength is linearly related to inspiratory pump muscle strength. The ratio of UA muscle strength (TP force) and inspiratory pump muscle strength (Pimax) was not different between individuals with and without OSA; however, a high wakeful ratio of TP force to Pimax appears to be associated with a reduced propensity to moderate-to-severe OSA.

Section snippets

Subjects

Ninety-four consecutive patients (52 men and 42 women) attending the Respiratory Sleep Disorders Clinic at Sir Charles Gairdner Hospital for overnight polysomnography were recruited into the study (Table 1). Subjects were excluded from participation if they had been or were being treated with continuous positive airway pressure, had undergone previous surgical treatment for sleep-disordered breathing, or if they had neuromuscular or pulmonary disease. This study was approved by the Sir Charles

Subjects

A total of 94 subjects were studied (Table 1). As a group, they were obese (BMI, 32 ± 8 kg/m2) and had moderate OSA (AHI, 25 ± 30/h). Compared to female subjects, male subjects were taller and had greater neck circumference. BMI, AHI, neck circumference, and cricomental space were greater in subjects with OSA vs subjects without OSA (Table 2). On average, subjects slept for 5.8 ± 1.7 h, had an average sleep efficiency of 76.1 ± 12.6%, and spent 2.3 ± 3.4% of the night in stage 1 sleep, 66.8 ±

Discussion

This study measured the strength of UA dilator and inspiratory pump muscles in individuals with and without OSA, and examined the potential for measurements of the relative force-generating capacity of these muscles to identify individuals who may be susceptible to UA collapse during sleep (ie, OSA). The major findings of the study were as follows: (1) in both male and female subjects and when all subjects were considered as a single group, TP force was greater when measured supine than seated;

ACKNOWLEDGMENT

We wish to thank the technical staff of the West Australian Sleep Disorders Research Institute for their support.

References (24)

  • SmirneS et al.

    Muscle fibre type and habitual snoring

    Lancet

    (1991)
  • HeJ et al.

    Mortality and apnea index in obstructive sleep apnea: experience in 385 male patients

    Chest

    (1988)
  • RemmersJE et al.

    Pathogenesis of upper airway occlusion during sleep

    J Appl Physiol

    (1978)
  • SantosC et al.

    Sleep-related breathing disorders in amyotrophic lateral sclerosis

    Monaldi Arch Chest Dis

    (2003)
  • SeriesF et al.

    Physiologic, metabolic, and muscle fiber type characteristics of musculus uvulae in sleep apnea hypopnea syndrome and in snorers

    J Clin Invest

    (1995)
  • CarreraM et al.

    Patients with obstructive sleep apnea exhibit genioglossus dysfunction that is normalized after treatment with continuous positive airway pressure

    Am J Respir Crit Care Med

    (1999)
  • BoydJH et al.

    Upper airway muscle inflammation and denervation changes in obstructive sleep apnea

    Am J Respir Crit Care Med

    (2004)
  • MortimoreIL et al.

    Tongue protrusion strength and fatigability: relationship to apnoea/hypopnoea index and age

    J Sleep Res

    (2000)
  • WeinerP et al.

    Influence of excessive weight loss after gastroplasty for morbid obesity on respiratory muscle performance

    Thorax

    (1998)
  • YapJC et al.

    Effects of posture on respiratory mechanics in obesity

    J Appl Physiol

    (1995)
  • NaimarkA et al.

    Compliance of the respiratory system and its components in health and obesity

    J Appl Physiol

    (1960)
  • MortimoreIL et al.

    Tongue protrusion force and fatigability in male and female subjects

    Eur Respir J

    (1999)
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    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

    The authors have no conflict of interests with any part of this study to disclose.

    This study was funded, in part, by National Health and Medical Research Council (Australia) Grant No. 303218. Dr. Eastwood was supported by a National Health and Medical Research Council (Australia) R. Douglas Wright Fellowship (No. 294404).

    Ms. Shepherd, Dr. Eastwood, and Dr. Hillman contributed to the study conception, design, data interpretation, and preparation and revision of the manuscript. Ms. Shepherd, Ms. Jensen, and Ms. Maddison were primarily responsible for data collection.

    This article was submitted through the West Australian Sleep Disorders Research Institute, Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands, Western Australia.

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