Hypoxic burden 低氧負荷

低氧負荷(Hypoxic burden, HB)是睡眠醫學中一個新興且愈來愈被廣泛採用的指標，特別是對於阻塞性睡眠呼吸中止症(OSA)，低氧負荷比目前臨床上最常用的呼吸中止低通氣指數(AHI)更能有效地衡量心血管疾病風險、器官受損嚴重程度（如腦部、心臟）和死亡率。

Hypoxic burden is an advanced, and increasingly used metric in sleep medicine, specifically for obstructive sleep apnea (OSA). It goes beyond traditional measurements,  the Apnea-Hypopnea Index (AHI), in evaluating cardiovascular disease risk, organ damage severity (such as brain, heart) and mortality.


傳統的AHI將每次呼吸事件視為相同，只統計呼吸事件的頻率；而低氧負荷則量化血氧飽和度下降的累積量（一個event從onset到恢復，底下面積的積分），綜合掉血氧的程度和持續時間，而不僅僅是頻率。
因此，低氧負荷能更精確地反映缺氧的實際嚴重程度。
AHI treats every event the same and only counts the frequency of breathing events, but hypoxic burden quantifies the cumulative amount of oxygen desaturation, which reveals the depth and duration of hypoxia, not just frequency.
So the hypoxic burden provides a more precise look at the actual severity of oxygen deprivation.

一項研究發現27.5%的輕度阻塞性睡眠呼吸中止症的患者(AHI 5~14.9)實際上有較高的低氧負荷(> 88%min/hr)，這解釋了為什麼一些「輕度」睡眠呼吸中止症患者症狀卻很明顯。所以即使AHI較低，低氧負荷也能識別出有高風險併發症的患者。
低氧負荷 60-75%min/hr 以上，就代表處於高度的低氧負荷狀態，與高風險的嚴重不良心血管疾病有關。
One study found that 27.5% of patients with mild AHI (5–14.9) actually had a high HB (>88 %min/hr), explaining why some "mild" patients are highly symptomatic. HB can identify patients at risk for comorbidities even if their AHI is low.
A hypoxic burden > 60–75 %min/hr is considered high, often associated with a higher risk of major adverse cardiovascular events.

重度阻塞性睡眠呼吸中止症患者往往有很高的低氧負荷，夜間睡著時嚴重且持續掉血氧，這會對身體造成巨大的缺氧負擔，可引發以下症狀：
♣ 過度嗜睡，影響日常生活、駕駛或工作
♣ 晨起頭痛
♣ 響亮的鼾聲，伴隨發出窒息音、喘息，或無聲的呼吸暫停
♣ 認知功能障礙，例如：記憶力減退、注意力不集中、執行功能缺陷
♣ 神經行為改變，例如：情緒失調、易怒，在兒童表現是過度活躍或尿床
♣ 睡不安穩，頻繁醒來，有時需要排尿（夜尿症）
♣ 慢性低氧會導致杵狀指或皮膚色澤晦暗
High hypoxic burden, often present in severe OSA, leads to severe, prolonged nocturnal oxygen drops. This causes significant strain on the body, resulting in the following symptoms: 
♣ Excessive sleepiness that interferes with daily life, driving, or working
♣ Morning Headaches
♣ Loud, habitual snoring interrupted by choking, gasping, or silent, paused breathing
♣ Cognitive Dysfunction: Trouble focusing, memory loss, impaired attention, and executive function deficits.
♣ Neurobehavioral Changes: Mood disturbances, irritability, or, in children, overactivity/bedwetting.
♣ Restless Sleep: Waking up frequently, sometimes to urinate (nocturia).
♣ Chronic low oxygen can lead to "clubbing" (enlargement) of fingertips, or a bluish/grey skin tone.

低氧負荷的檢測需要有監測夜間睡眠期間血氧飽和度的數據，這些通常是在診斷性睡眠檢測中會記錄（睡眠中心睡一晚的多項式睡眠檢查，或居家型睡眠呼吸中止症檢測）。
其他較近似的、替代低氧負荷的生理指標，可以看 T90（血氧飽和度低於 90% 的時間）和 ODI3/4（血氧飽和度下降 3% 或 4% 的指數）。
Hypoxic burden is calculated using overnight oximetry data, usually obtained during a diagnostic sleep study (polysomnography or home sleep apnea test).
Alternative metrics can include T90 (time below 90% saturation) and ODI3/4 (Oxygen Desaturation Index by 3% or 4%).


AHI在預測長期結果方面表現不佳，但低氧負荷可以更準確地反映缺氧的實際嚴重程度，因此可作為更好的預後指標。
低氧負荷已被用於評估治療（像是戴CPAP治療）的真正效果，因為即使治療不能顯著降低呼吸事件的總數(AHI)，實際上也可能減輕了掉血氧的程度。
While AHI is poor at predicting long-term outcomes, hypoxic burden provides a more precise look at the actual severity of oxygen deprivation and better prognostic utility.
Hypoxic burden has been used to evaluate the true effectiveness of treatments (such as CPAP), as a treatment might reduce the depth of desaturations even if it does not significantly lower the total number of events (AHI).


雖然目前還不是主要的診斷指標，但低氧負荷愈來愈常被用於輔助臨床決策，尤其是必須優先治療高風險患者時。
更先進的技術、人工智慧驅動的、經FDA核准的居家型睡眠呼吸中止症檢測設備，使得在臨床更自動化、常規地檢測低氧負荷成為可能。
While not yet the primary, official metric, it is increasingly used to aid in clinical decision-making, particularly to prioritize treatment for patients with high-risk profiles.
Modern, AI-driven, FDA-approved home sleep apnea tests are enabling the automated, routine calculation of hypoxic burden in clinical settings.

雖然目前睡眠呼吸中止症的診斷標準仍然使用AHI，但睡眠醫學領域未來走向精準醫療，也正在推動採用其他指標，像是低氧負荷，以更好地反映阻塞性睡眠呼吸中止症的真實嚴重程度，以及患者對於治療的反應。
While traditional metrics like AHI are still the baseline for initial diagnosis (due to established guidelines), the shift toward "precision medicine" in sleep care is driving the adoption of hypoxic burden to better characterize the true severity of OSA, and the patient's response to treatment.

◬ ⟁ ⧋ ◬ ⟁ ⧋ ◬ 我想寫這個主題很久了。 我累積了好多要寫的主題，這是最近的一個。 終於有心情寫東西了