Laboratory of Respiratory Pathophysiology (LAFIR), Federal University of Mato Grosso do Sul (UFMS)/Maria Aparecida Pedrossian Hospital (HUMAP), Campo Grande, Mato Grosso do Sul, Brazil.
Biostatistical Department, Mathematical Institute (INMA), Federal University of Mato Grosso do Sul (UFMS), Campo Grande, Mato Grosso do Sul, Brazil.
Clin Physiol Funct Imaging. 2021 Jan;41(1):103-109. doi: 10.1111/cpf.12674. Epub 2020 Nov 11.
BACKGROUND/OBJECTIVE: The current approach to measuring ventilatory (in)efficiency (V' -V'CO slope, nadir and intercept) presents critical drawbacks in the evaluation of COPD subjects, owing mainly to mechanical ventilatory constraints. Thus, we aimed to compare the current approach with a new method we have developed for ventilatory efficiency calculation.
The new procedure was based on measuring the amount of CO cleared by the lungs (V'CO , L/min) plotted against a predefined range of increase in minute ventilation (V' ) (ten-fold increase based on semilog scale) during incremental exercise to symptom-limited maximum tolerance. This value was compared to a hypothetical predicted maximum CO output at the predicted maximal voluntary ventilation, defining ventilatory efficiency (ηV' , %). The results were used to compare 30 subjects with COPD (II-IV Global Initiative for Chronic Obstructive Lung Disease, GOLD) and 10 non-COPD smokers, to establish the best discriminative physiological variable for disease severity through logistic multinomial regression.
The new approach was more sensitive to progressive deterioration of airway obstruction, resulting in worse ηV' as lung function worsens throughout the GOLD panel (ηV' (%), p < .001), when compared with V' -V'CO slope (p = .715) or V' -V'CO nadir (p = .070), besides showing the best model based on the logistic regression approach.
Although requiring more complex calculations compared to the current procedure, the new approach is highly sensitive to true ventilatory/gas-exchange deterioration, even throughout more severe pulmonary lung function in COPD subjects.
背景/目的：目前测量通气（效率）（V' - V'CO 斜率、最低点和截距）的方法在评估 COPD 患者时存在严重缺陷，主要是由于机械通气的限制。因此，我们旨在比较目前的方法和我们开发的一种新的通气效率计算方法。
新方法基于测量肺部清除的 CO 量（V'CO ，L/min）与递增运动至症状限制最大耐受时分钟通气量（V'）（基于半对数标度的十倍增加）的预定范围之间的关系。该值与预测最大自主通气时预测的最大 CO 输出进行比较，定义通气效率（ηV'，%）。结果用于比较 30 例 COPD 患者（GOLD II-IV 期）和 10 例非 COPD 吸烟者，通过逻辑多项回归确定用于疾病严重程度的最佳鉴别生理变量。
与 V' - V'CO 斜率（p =.715）或 V' - V'CO 最低点（p =.070）相比，新方法对气道阻塞的进行性恶化更为敏感，导致随着 GOLD 组中肺功能的恶化，ηV'变得更差（ηV'（%），p <.001），与 V' - V'CO 斜率相比，新方法更敏感。此外，新方法基于逻辑回归方法显示了最佳模型。
与目前的方法相比，尽管需要更复杂的计算，但新方法对真正的通气/气体交换恶化非常敏感，即使在 COPD 患者更严重的肺部功能中也是如此。
