title: Breath-holding time in normal subjects, snorers, and sleep apnea patients.
abstract: BACKGROUND
  The onset of irregular inspiratory muscle activity has been observed toward the breakpoint of the breath-holding maneuver. We wondered if this was similar to the increased respiratory effort with paradoxical breathing seen during the resolution of an apnea in obstructive sleep apnea syndrome (OSAS).
  
  
  OBJECTIVE
  To compare the breakpoint of breath holding in normal subjects, OSAS patients, and snorers.
  
  
  METHODS
  Thirty normal subjects, 30 patients with OSAS, and 16 snorers performed serial breath-holding maneuvers at functional residual capacity (FRC) under standardized pretest conditions using the rebreathing method of Read.
  
  
  RESULTS
  Intergroup comparisons were carried out by analysis of variance with post hoc Tukey's Highest Significant Difference tests. Basal end-tidal carbon dioxide (EtCO2) was significantly higher in OSAS than in normal subjects and snorers. Basal breath-holding time (BHT) was shorter in OSAS as compared with that in normal subjects and snorers (p < 0.05). The maximal EtCO2 level attained was higher in OSAS as compared with normal subjects (p < 0.05) and snorers (p = 0.052). The maximal BHT in OSAS was shorter than in normal subjects (p < 0.05) but not in snorers. The slope of BHT/EtCO2 differed significantly in OSAS compared with normal subjects and snorers (p < 0.05). No significant correlation was found between slope BHT/EtCO2 and age or body mass index using multiple regression analysis. The FRC of OSAS patients and snorers were similar (p = 0.792).
  
  
  CONCLUSIONS
  We conclude that BHT and slope of BHT/EtCO2 are different in OSAS subjects as opposed to those in normal subjects and snorers.
authors.affiliation: Department of Respiratory Physiology, Wythenshawe Hospital, Manchester, England.
authors.forename: V
authors.initials: V
authors.lastname: Taskar
authors.forename: N
authors.initials: N
authors.lastname: Clayton
authors.forename: M
authors.initials: M
authors.lastname: Atkins
authors.forename: Z
authors.initials: Z
authors.lastname: Shaheen
authors.forename: P
authors.initials: P
authors.lastname: Stone
authors.forename: A
authors.initials: A
authors.lastname: Woodcock
mesh_terms: D002245:Carbon Dioxide; D005260:Female; D005652:Functional Residual Capacity; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D012119:Respiration; D012132:Respiratory Muscles / Q000503:physiopathology; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012913:Snoring / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide