Little S A, Elkholy M M, Chalmers G W, Farouk A, Patel K R, Thomson N C
Department of Respiratory Medicine, West Glasgow Hospitals University NHS Trust, U.K.
Respir Med. 1999 Mar;93(3):202-7. doi: 10.1016/s0954-6111(99)90009-4.
The aim of this study was to identify factors which might predict nocturnal desaturation (defined as a fall of > 4% from awake baseline level for > or = 5 min) in normoxic or mildly hypoxic patients with stable COPD [arterial O2 saturation (SaO2) > or = 91%]. The study was prospective in nature, had full ethical approval and was performed in the Respiratory Department of a city teaching hospital. Thirty-three patients [mean (SD) age 67.2 (9) years] with stable COPD [mean (SD) FEV1 36.8 (11.0)% pred.] were recruited via the respiratory outpatient clinics and through the respiratory wards. The following parameters were measured: daytime arterial blood gases; spirometry; lung volumes (helium dilution); single breath CO transfer factor (TLCO and KCO); maximum inspiratory (IMP) and expiratory mouth pressures; pulse oximetry (SpO2) across a 6-min walk test, and SpO2 during sleep. Seventeen patients who experienced nocturnal desaturation had significantly lower mean PaO2 and SaO2, and higher PaCO2 values compared to non-desaturators. There was a positive correlation between mean nocturnal SpO2 and daytime PaO2, SaO2, and minimum exercise SpO2, and a negative correlation between mean nocturnal SpO2 and PaCO2, and FRC. Regression analysis revealed that daytime SaO2 was the only independent predictor of mean nocturnal saturation (accounting for 61% of the variability in the mean nocturnal SpO2). We observed nocturnal desaturation in all patients with a daytime SaO2 < or = 93% but in no patient with SaO2 > or = 95%. We conclude that daytime SaO2 can be used to predict nocturnal desaturation in normoxic or mildly hypoxic patients with stable COPD. Nocturnal desaturation is likely in patients with COPD where daytime SaO2 < or = 93%, and unlikely where daytime SaO2 > or = 95%.
本研究旨在确定可能预测稳定期慢性阻塞性肺疾病（COPD）且动脉血氧饱和度（SaO2）≥91%的常氧或轻度低氧患者夜间血氧饱和度下降（定义为从清醒基线水平下降>4%且持续≥5分钟）的因素。本研究为前瞻性研究，获得了充分的伦理批准，在一家城市教学医院的呼吸科进行。通过呼吸门诊和呼吸病房招募了33例稳定期COPD患者[平均（标准差）年龄67.2（9）岁]，其[平均（标准差）第一秒用力呼气容积（FEV1）为预计值的36.8（11.0）%]。测量了以下参数：日间动脉血气；肺功能测定；肺容积（氦稀释法）；单次呼吸一氧化碳弥散量（TLCO和KCO）；最大吸气（IMP）和呼气口腔压力；6分钟步行试验期间的脉搏血氧饱和度（SpO2）以及睡眠期间的SpO2。与未出现夜间血氧饱和度下降的患者相比，17例出现夜间血氧饱和度下降的患者平均动脉血氧分压（PaO2）和SaO2显著更低，而PaCO2值更高。夜间平均SpO2与日间PaO2、SaO2以及最低运动时SpO2呈正相关，与PaCO2和功能残气量（FRC）呈负相关。回归分析显示，日间SaO2是夜间平均血氧饱和度的唯一独立预测因素（占夜间平均SpO2变异性的61%）。我们观察到，日间SaO2≤93%的所有患者均出现夜间血氧饱和度下降，而日间SaO2≥95%的患者均未出现。我们得出结论，日间SaO2可用于预测稳定期COPD常氧或轻度低氧患者的夜间血氧饱和度下降。日间SaO2≤93%的COPD患者夜间很可能出现血氧饱和度下降，而日间SaO2≥95%的患者则不太可能出现。
