息苦しさは重要な診断指標―正常酸素濃度でも「静かな窒息」の恐れ(Dyspnea matters: Normal oxygen levels may hide “silent suffocation”)

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2026-07-08 カリフォルニア大学リバーサイド校(UCR)

カリフォルニア大学リバーサイド校(UCR)の研究チームは、呼吸困難(呼吸苦)の評価において血中酸素飽和度(SpO₂)だけに依存する現在の臨床判断には限界があることを示した。約70人の健常者を対象に、酸素濃度と二酸化炭素濃度を調整して呼吸困難を誘発する実験を行った結果、息苦しさの感覚は酸素不足よりも二酸化炭素濃度の上昇と強く関連することが判明した。また、外見上は落ち着いて見える人ほど強い呼吸苦を訴える例もあり、患者の状態は外観やSpO₂だけでは正確に把握できないことが示された。研究チームは、呼吸困難を客観的に評価するため、非侵襲的な生体指標を用いて人工知能(機械学習)が呼吸苦を予測する手法を開発している。この成果は、人工呼吸器装着患者や意思表示が困難な重症患者における呼吸苦の早期検出や、「サイレント低酸素症」の見逃し防止につながる可能性があり、より適切な呼吸管理と患者ケアへの応用が期待される。

息苦しさは重要な診断指標―正常酸素濃度でも「静かな窒息」の恐れ(Dyspnea matters: Normal oxygen levels may hide “silent suffocation”)
Header image credit: Mufid Majnun on Unsplash

<関連情報>

非侵襲性バイオマーカーを用いた呼吸困難予測のための機械学習アプローチ A machine learning approach to predicting dyspnea with noninvasive biomarkers

Karapet G. Mkrtchyan, Anser Qazi, Borena Lonh, Andrew Dong, Gustavo O. Ramirez, Mona Eskandari, Shujie Ma, Wei Vivian Li, Erica C. Heinrich
Respiratory Physiology & Neurobiology  Available online: 12 April 2026
DOI:https://doi.org/10.1016/j.resp.2026.104572

Highlights

  • There is significant individual variation in dyspnea severity during free breathing.
  • Dyspnea in free-breathing individuals can be predicted using noninvasive biomarkers.
  • Machine-learning prediction models are more accurate than observational estimates.
  • Subjective symptoms can be predicted using noninvasive biomarker inputs.

Abstract

Dyspnea is the subjective sensation of breathing discomfort. This symptom is highly prevalent in patients with chronic and critical illness, and its presence is associated with poor clinical outcomes and long-term psychological trauma. The multidimensional nature of the neurophysiological mechanisms underlying dyspnea, paired with individual variation in its presentation, makes identifying and monitoring this symptom difficult, particularly in non-communicative patients. Undetected and untreated dyspnea in critically ill patients is a significant problem contributing to patient suffering. Therefore, the objective of this study was to investigate the feasibility of machine learning methods for assessing and continuously monitoring dyspnea using easily obtained noninvasive biomarkers. We recruited healthy participants (N = 60, 35 women) and stimulated dyspnea using a forced end-tidal semi-rebreathing circuit to modulate arterial oxygen and carbon dioxide levels while collecting non-invasive biomarker data and continuous self-reported dyspnea severity scores. This data was used to train machine-learning models to predict the presence or absence of significant dyspnea (Numeric Rating Scale ≥ 3). We then compared the performance of our final model to observational estimates by trained healthcare providers. The final model (Random Forest) performed well (PR-AUC=0.822) and exceeded the accuracy of observation estimates made on the same participants using the Respiratory Distress Observational Scale (RDOS) (accuracy=54%). These results indicate that machine learning models can utilize non-invasive biomarker inputs to accurately predict carbon dioxide- and hypoxia-induced dyspnea in a healthy population during spontaneous breathing.

医療・健康
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