Francis D P, Willson K, Davies L C, Coats A J, Piepoli M
Royal Brompton Hospital, National Heart and Lung Institute, London,
Circulation. 2000 Oct 31;102(18):2214-21. doi: 10.1161/01.cir.102.18.2214.
In patients with chronic heart failure (CHF), periodic breathing (PB) predicts poor prognosis. Clinical studies have identified numerous risk factors for PB (which also includes Cheyne-Stokes respiration). Computer simulations have shown that oscillations can arise from delayed negative feedback. However, no simple general theory quantitatively explains PB and its mechanisms of treatment using widely-understood clinical concepts. Therefore, we introduce a new approach to the quantitative analysis of the dynamic physiology governing cardiorespiratory stability in CHF.
An algebraic formula was derived (presented as a simple 2D plot), enabling prediction from easily acquired clinical data to determine whether respiration will be unstable. Clinical validation was performed in 20 patients with CHF (10 with PB and 10 without) and 10 healthy normal subjects. Measurements, including chemoreflex sensitivity (S) and delay (delta), alveolar volume (V(L)), and end-tidal CO(2) fraction (C), were applied to the stability formula. The breathing pattern was correctly predicted in 28 of the 30 subjects. The principal combined parameter (CS)x(delta/V(L)) was higher in patients with PB (14.2+/-3.0) than in those without PB (3.1+/-0.5; P:=0.0005) or in normal controls (2.4+/-0.5; P:=0.0003). This was because of differences in both chemoreflex sensitivity (1749+/-235 versus 620+/-103 and 526+/-104 L/min per atm CO(2); P:=0.0001 and P:<0.0001, respectively) and chemoreflex delay (0.53+/-0.06 vs 0.40+/-0.06 and 0.30+/-0.04 min; P:=NS and P:=0.02).
This analytical approach identifies the physiological abnormalities that are important in the genesis of PB and explicitly defines the region of predicted instability. The clinical data identify chemoreflex gain and delay time (rather than hyperventilation or hypocapnia) as causes of PB.
在慢性心力衰竭（CHF）患者中，周期性呼吸（PB）预示着预后不良。临床研究已确定了PB（其中还包括潮式呼吸）的众多危险因素。计算机模拟表明，振荡可由延迟负反馈产生。然而，尚无简单的通用理论能使用广泛理解的临床概念定量解释PB及其治疗机制。因此，我们引入了一种新方法来定量分析CHF中心肺稳定性的动态生理学。
推导了一个代数公式（以简单的二维图呈现），可根据易于获取的临床数据进行预测，以确定呼吸是否会不稳定。对20例CHF患者（10例有PB，10例无PB）和10名健康正常受试者进行了临床验证。将包括化学反射敏感性（S）和延迟（δ）、肺泡容积（V(L)）以及呼气末二氧化碳分数（C）等测量值应用于稳定性公式。30名受试者中有28名的呼吸模式被正确预测。PB患者的主要综合参数（CS）×（δ/V(L)）（14.2±3.0）高于无PB患者（3.1±0.5；P = 0.0005）或正常对照组（2.4±0.5；P = 0.0003）。这是由于化学反射敏感性（分别为1749±235与620±103和526±104 L/min per atm CO₂；P = 0.0001和P < 0.0001）以及化学反射延迟（0.53±0.06 vs 0.40±0.06和0.30±0.04分钟；P = 无显著性差异和P = 0.02）均存在差异。
这种分析方法确定了在PB发生过程中重要的生理异常，并明确界定了预测不稳定区域。临床数据表明化学反射增益和延迟时间（而非过度通气或低碳酸血症）是PB的原因。
