The Pharyngeal Critical Pressure

Abstract

apnea/hypopnea index continuous positive airway pressure nonrapid eye movement critical pressure pressure downstream to the collapsible segment esophageal pressure pressure within the segment nasal mask pressure pressure outside collapsible segment pressure upstream to the collapsible segment resistance of portion of tube upstream to site of collapse upper airway resistance syndrome uvulopalatopharyngoplasty maximal inspiratory flow maximal flow Obstructive sleep apnea is a disorder characterized by pharyngeal collapse and occlusion during sleep. The disorder affects between 2% and 5% of the middle-aged population1Young T Palta M Dempsey J et al.Occurrence of sleep disordered breathing among middle-aged adults.N Engl J Med. 1993; 328: 1230-1235Crossref PubMed Scopus (8337) Google Scholar and is associated with significant morbidity and mortality.2Guilleminault C Stoohs R Partinen M et al.Mortality and morbidity of obstructive sleep apnea syndrome: prospective studies on retrospective cohorts.in: Saunders NA Sullivan CE 2nd ed. Sleep and breathing. Marcel Dekker, New York1994: 557-574Google Scholar The mechanism responsible for pharyngeal collapse during sleep remains uncertain. Investigators have identified both anatomic factors3Haponik EF Smith PL Bohlman ME et al.Computerized tomography in obstructive sleep apnea: correlation of airway size with physiology during sleep and wakefulness.Am Rev Respir Dis. 1983; 127: 221-226PubMed Google Scholar, 4Bradley TD Brown IG Grossman RF et al.Pharyngeal size of snorers, non-snorers, and patients with obstructive sleep apnea.N Engl J Med. 1986; 315: 1327-1331Crossref PubMed Scopus (233) Google Scholar, 5Schwab RJ Gefter WB Hoffman EA et al.Dynamic upper airway imaging during awake respiration in normal subjects and patients with sleep disordered breathing.Am Rev Respir Dis. 1993; 148: 1385-1400Crossref PubMed Scopus (406) Google Scholar, 6Shelton KE Woodson H Gay S et al.Pharyngeal fat in obstructive sleep apnea.Am Rev Respir Dis. 1993; 148: 462-466Crossref PubMed Scopus (354) Google Scholar and neuromuscular control factors7Remmers JE DeGroot WJ Sauerland EK et al.Pathogenesis of upper airway occlusion during sleep.J Appl Physiol. 1978; 44: 931-938Crossref PubMed Scopus (1396) Google Scholar, 8Anch AM Remmers JE Sauerland EK et al.Oropharyngeal patency during waking and sleep in the pickwickian syndrome: electromyographic activity of the tensor veli palatini.Electromyogr Clin Neurophysiol. 1981; 21: 317-330PubMed Google Scholar, 9Jeffries B Brouillette RT Hunt CE. Electromyographic study of some accessory muscles of respiration in children with obstructive sleep apnea.Am Rev Respir Dis. 1984; 129: 696-702Crossref PubMed Scopus (54) Google Scholar, 10Suratt PM McTier R Wilhoit SC. Alae nasi electromyographic activity and timing in obstructive sleep apnea.J Appl Physiol. 1985; 58: 1252-1256Crossref PubMed Scopus (19) Google Scholar that may lead to increased pharyngeal collapsibility during sleep in patients with obstructive sleep apnea.Although our understanding of the factors responsible for pharyngeal collapse during sleep is limited, treatments have been developed to oppose pharyngeal collapse during sleep in patients with obstructive sleep apnea. One such treatment, nasal continuous positive airway pressure (nasal CPAP), is often prescribed to offset the increase in pharyngeal collapsibility during sleep.11Sullivan CE Issa FG Berthon-Jones M et al.Reversal of obstructive sleep apnoea by continuous positive pressure applied through the nares.Lancet. 1981; 1: 862-865Abstract PubMed Scopus (2024) Google Scholar,12Sullivan CE Issa FG Berthon-Jones M et al.Home treatment of obstructive sleep apnoea with continuous positive pressure applied through a nose-mask.Bull Eur Physiopathol Respir. 1984; 20: 49-54PubMed Google Scholar When an appropriate level of nasal CPAP is prescribed, this treatment is highly effective at opening the during sleep of the mechanism for pharyngeal with nasal is to of patients nasal CPAP and treatment Saunders of continuous positive airway pressure in obstructive sleep apnea.Am Rev Respir Dis. PubMed Scopus Google Scholar, et of of nasal CPAP by patients with obstructive sleep apnea.Am Rev Respir Dis. 1993; PubMed Scopus Google Scholar, R an of J Respir Med. PubMed Scopus Google Scholar effective treatments for obstructive sleep apnea to nasal CPAP in patients treatments to the of obstructive sleep apnea. treatments the The of on sleep disordered breathing and in PubMed Scopus Google Scholar, PL et in patients with obstructive sleep Med. 1985; PubMed Scopus (354) Google Scholar, PM McTier ME et in breathing and the in obstructive sleep PubMed Scopus Google Scholar et in obstructive sleep apnea: a Engl J Med. PubMed Scopus Google PL EF et of in sleep disordered breathing.Am Rev Dis. 1983; 127: PubMed Scopus Google Scholar S et of upper airway in obstructive sleep apnea syndrome: 1981; PubMed Scopus Google Scholar, C and some obstructive sleep ap