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The carbon dioxide reserve is reduced and chemoreflex sensitivity is increased in the morning compared to the evening and afternoon in participants with sleep apnea (1178.7)
Author(s) -
El Chami Mohamad,
Syed Ziauddin,
Shaheen David,
Ivers Blake,
Badr M. Safwan,
Lin HoSheng,
Mateika Jason
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1178.7
Subject(s) - morning , evening , anesthesia , medicine , apnea , obstructive sleep apnea , ventilation (architecture) , sleep apnea , hypercapnia , continuous positive airway pressure , breathing , respiratory minute volume , respiratory system , mechanical engineering , physics , astronomy , acidosis , engineering
Purpose: Clinical studies have indicated that breathing instability in patients with sleep apnea is increased in the morning independent of sleep stage. Upper airway collapsibility and chemoreflex responses to hypoxia/hypercapnia have a major influence on breathing stability during sleep. Thus we hypothesized that these parameters would be greater in the morning compared to the evening and afternoon. Methods: Five participants with sleep apnea slept for 3 hours in the evening, morning and afternoon while upper airway patency was maintained with positive airway pressure. Intermittently the pressure was reduced for a period of 3‐5 breaths until the airway collapsed. On a separate occasion the protocol was repeated and the threshold (i.e. apneic threshold) and sensitivity of the chemoreflex response to carbon dioxide was determined by applying 3‐minute periods of mechanical ventilation followed by 5 minutes of recovery. Results: Upper airway collapsibility was not significantly greater in the morning compared to the other sessions (1.87 ± 2.48 vs. ‐ 0.22 ± 1.10 cmH 2 O). However, chemoreflex sensitivity was greater (2.38 ± 0.36 vs.1.88 ± 0.33 L/min/mmHg, p = 0.05) and carbon dioxide (CO 2 ) values that demarcated the apneic threshold (morning: 38.24 ± 0.36 vs. afternoon/evening: 38.09 ± 0.88 mmHg) were closer to resting values in the morning compared to the other sessions (Δ CO 2 :1.85 ± 0.20 vs. 3.02 ± 0.19 mmHg, p = 0.001). Conclusions: Increased breathing instability in the morning may be a consequence of alterations in chemoreflex properties that vary across the 24 hr cycle. Grant Funding Source : Supported by VA Merit Award (2I01CX000125‐05A1) (JHM)