Javaheri S, Corbett W S
Department of Veterans Affairs Medical Center, Cincinnati, Ohio, USA.
Ann Intern Med. 1998 Feb 1;128(3):204-7. doi: 10.7326/0003-4819-128-3-199802010-00006.
Central sleep apnea frequently occurs in patients with heart failure. Because it is not practical to perform sleep studies on all patients, readily available laboratory tests that predict sleep apnea would be clinically useful. Arterial PCO2 has a profound influence on breathing during sleep: When it decreases below a certain threshold, apnea occurs.
To study the value of a low PaCO2 while patients are awake in predicting central sleep apnea in patients with stable, treated heart failure.
Prospective study.
Referral sleep laboratory of a Department of Veterans Affairs Medical Center.
59 patients with left ventricular ejection fractions of 45% or less.
Arterial blood gases and hydrogen ion concentrations were measured, and cardiac radionuclide ventriculography, Holter monitoring, and polysomnography were done.
Patients were classified as eucapnic (PaCO2 > 35 and < 44 mm Hg [n = 41]) or hypocapnic (PaCO2 < or = 35 mm Hg [n = 18]). The mean (+/- SD) hourly episodes of apnea or hypopnea (36 +/- 25 and 20 +/- 27; P = 0.015), the prevalence of central sleep apnea (78% and 39%; P = 0.01), and the mean hourly occurrences of ventricular tachycardia (2 +/- 3 and 0.1 +/- 0.1; P = 0.003) were significantly greater in hypocapnic patients than in eucapnic patients.
Data on patients with heart failure in this study are consistent with the physiologic notion that a low PaCO2 results in ventilatory instability and central apnea during sleep. The positive predictive value of a low PaCO2 for central sleep apnea is 78%. The prevalence of ventricular tachycardia was 20 times greater in hypocapnic patients than in eucapnic patients.
中枢性睡眠呼吸暂停在心力衰竭患者中经常出现。由于对所有患者进行睡眠研究并不实际，因此能够预测睡眠呼吸暂停的现成实验室检查在临床上将很有用。动脉血二氧化碳分压（PCO₂）对睡眠期间的呼吸有深远影响：当它降至某个阈值以下时，就会出现呼吸暂停。
研究清醒时低动脉血二氧化碳分压（PaCO₂）对稳定的、接受治疗的心力衰竭患者中枢性睡眠呼吸暂停的预测价值。
前瞻性研究。
一家退伍军人事务医疗中心的转诊睡眠实验室。
59名左心室射血分数为45%或更低的患者。
测量动脉血气和氢离子浓度，并进行心脏放射性核素心室造影、动态心电图监测和多导睡眠图检查。
患者被分为血二氧化碳正常（PaCO₂>35且<44 mmHg [n = 41]）或低血二氧化碳（PaCO₂≤35 mmHg [n = 18]）。低血二氧化碳患者每小时的呼吸暂停或呼吸浅慢发作次数（36±25和20±27；P = 0.015）、中枢性睡眠呼吸暂停的患病率（78%和39%；P = 0.01）以及每小时室性心动过速的发作次数（2±3和0.1±0.1；P = 0.003）均显著高于血二氧化碳正常的患者。
本研究中关于心力衰竭患者的数据与低PaCO₂导致睡眠期间通气不稳定和中枢性呼吸暂停的生理学概念一致。低PaCO₂对中枢性睡眠呼吸暂停的阳性预测值为78%。低血二氧化碳患者室性心动过速的患病率比血二氧化碳正常的患者高20倍。
