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Sleep Med Res > Volume 13(1); 2022 > Article
Sleep Medicine Research 2022;13(1): 15-21.
doi: https://doi.org/10.17241/smr.2021.01172
Awake Hypercapnic Ventilatory Response in Obstructive Sleep Apnea Syndrome
Takashi Sakuma MD1 , Shohei Shinomiya MD1 , Yutaka Takahara MD1 , Shiro Mizuno MD, PhD1
Department of Respiratory Medicine, Kanazawa Medical University, Ishikawa, Japan
Corresponding Author: Takashi Sakuma ,Tel: +81-76-218-8157, Fax: +81-76-286-0980, Email: takasi-s@kanazawa-med.ac.jp
Received: December 2, 2021.  Revised: February 25, 2022.  Accepted: March 31, 2022.
Background and Objective     Decreased ventilatory response to carbon dioxide or hypercapnic ventilatory response (HCVR) is a feature of pediatric obstructive sleep apnea (OSA) and is also known to diminish during sleep in obese adolescents (age, 12–16 years) with OSA. It reduces minute ventilation, air flow, and tidal volume during inspiration, as well as upper airway obstruction. The purpose of this study was to investigate awake HCVR in adult patients with OSA and to elucidate its association with sleep apnea.
Methods     HCVR was measured before performing polysomnography (PSG). PSG is performed as the evaluation method during sleep, and the severity of apnea is evaluated by apnea hypopnea index. Patient background, PSG data and HCVR were examined.
Results     Awake HCVR was greater in patients with severe OSA than in patients with mild and moderate OSA, and in severe OSA patients, the HCVR during awaking was higher in patients with larger changes in saturation of percutaneous oxygen during sleep. Awake HCVR did not differ by age, but it was greater in morbidly obese patients with OSA than in thin patients with OSA. The most frequent apnea pattern of OSA was obstructive, regardless of severity; although with an increasing severity of OSA, the central pattern decreased and the mixed pattern increased in frequency. The appearance of the mixed pattern increased in the augmented HCVR group.
Conclusions     This study suggested that awake HCVR could be used as an index of progression and a factor to determine the effects of treatment in patients with OSA.
Key Words: Obstructive sleep apnea; Hypercapnic ventilatory response; Polysomnography