Pulmonary Department, Pôle Cardio-thoracique, CHU Haut-Lévèque, INSERM U1045, Bordeaux, France.
Pulmonary Department, Maison Blanche University Hospital, INSERM U01250, Reims, France.
Int J Chron Obstruct Pulmon Dis. 2021 May 10;16:1275-1284. doi: 10.2147/COPD.S295381. eCollection 2021.
Chronic respiratory failure may occur as a consequence of chronic obstructive pulmonary disease (COPD) and is associated with significant morbidity and mortality. Hypoxemia is determined by underlying disease characteristics and comorbidities. Severe hypoxemia is typically only found in subjects with severe airflow obstruction (FEV<50% predicted). However, how hypoxemia relates to disease characteristics is not fully understood.
In the French Initiatives BPCO real-life cohort, arterial blood gases were routinely collected in most patients. Relationships between severe hypoxemia, defined by a Pa0<60 mmHg (8 kPa) and clinical/lung function features, comorbidities and mortality were assessed. In subjects with severe hypoxemia, clinical characteristics and comorbidities were compared between those with non-severe versus severe airflow limitation. Classification and regression trees (CART) were used to define clinically relevant subgroups (phenotypes).
Arterial blood gases were available from 887 subjects, of which 146 (16%) exhibited severe hypoxemia. Compared to subjects with a PaO2≥60 mmHg, the severe hypoxemia group exhibited higher mMRC dyspnea score, lower FEV, higher RV and RV/TLC, more impaired quality of life, lower 6-minute walking distance, less frequent history of asthma, more frequent diabetes and higher 3-year mortality rate (14% versus 8%, p=0.026). Compared to subjects with Pa0<60 mmHg and FEV<50% (n=115, 13%), those with severe hypoxemia but FEV1≥50% predicted (n=31) were older, had higher BMI, less hyperinflation, better quality of life and a higher rate of diabetes (29% versus 13%, p=0.02). Severe hypoxemia was better related to CART-defined phenotypes than to GOLD ABCD classification.
In this cohort of stable COPD subjects, severe hypoxemia was associated with worse prognosis and more severe symptoms, airflow limitation and hyperinflation. Compared to subjects with severe hypoxemia and severe airflow limitation, subjects with severe hypoxemia despite non-severe airflow limitation were older, had higher BMI and more diagnosed diabetes.
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慢性呼吸衰竭可能是由慢性阻塞性肺疾病（COPD）引起的，与显著的发病率和死亡率相关。低氧血症由基础疾病特征和合并症决定。严重低氧血症通常仅见于严重气流阻塞（FEV<50%预计值）的患者。然而，低氧血症与疾病特征的关系尚不完全清楚。
在法国的 INITIATIVES BPCO 真实世界队列中，大多数患者常规采集动脉血气。评估严重低氧血症（定义为 Pa0<60mmHg（8kPa））与临床/肺功能特征、合并症和死亡率之间的关系。在严重低氧血症患者中，比较了非严重与严重气流受限患者的临床特征和合并症。使用分类和回归树（CART）来定义临床相关亚组（表型）。
887 例患者的动脉血气结果可用，其中 146 例（16%）存在严重低氧血症。与 PaO2≥60mmHg 的患者相比，严重低氧血症组呼吸困难评分更高（mMRC），FEV 更低，RV 和 RV/TLC 更高，生活质量更差，6 分钟步行距离更短，哮喘病史更少，糖尿病更常见，3 年死亡率更高（14% vs. 8%，p=0.026）。与 Pa0<60mmHg 和 FEV<50%（n=115，13%）的患者相比，那些严重低氧血症但 FEV1≥50%预计值（n=31）的患者年龄更大，BMI 更高，充气过度程度更低，生活质量更好，糖尿病发生率更高（29% vs. 13%，p=0.02）。严重低氧血症与 CART 定义的表型的相关性优于 GOLD ABCD 分类。
在本队列的稳定 COPD 患者中，严重低氧血症与预后较差和更严重的症状、气流受限和充气过度相关。与严重低氧血症和严重气流受限的患者相比，那些严重低氧血症但气流受限不严重的患者年龄更大，BMI 更高，更易被诊断为糖尿病。
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