Varga Janos, Casaburi Richard, Ma Shuyi, Hecht Ariel, Hsia David, Somfay Attila, Porszasz Janos
Department of Pulmonology, University of Szeged, Deszk, Hungary; Department of Pulmonary Rehabilitation, National Koranyi Institute for TB and Pulmonology, Budapest, Hungary.
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
Respir Physiol Neurobiol. 2016 Dec;234:79-84. doi: 10.1016/j.resp.2016.08.005. Epub 2016 Aug 26.
Active expiration during exercise can increase intrathoracic pressure yielding concavity in the expiratory flow-volume loop in COPD. We investigated the relationship between this concavity and dynamic hyperinflation (DH). 17 COPD patients (FEV: 38±10%pred, GOLD stage 3-4) and 12 healthy subjects performed cycle ergometer incremental exercise. Expiratory limb of the spontaneous flow-volume loop was analyzed breath-by-breath using a geometric approach (rectangular area ratio (RAR), Respir. Med., 104(3):389-96, 2010). RAR below 0.5 demonstrates expiratory limb concavity. DH was determined with serial inspiratory capacity maneuvers. 5 of 17 patients displayed little end-exercise concavity (RAR=0.52±0.04, group LCONC). 12 patients had concavity at rest and end-exercise RAR reached 0.40±0.03 (group HCONC). Healthy subjects showed no concavity. End-exercise RAR correlated with resting FEV%pred (R=0.81, P<0.05). Group HCONC, compared to groups LCONC and H, reached significantly lower work rate, minute ventilation, and more dyspnea. DH inversely correlated with RAR (R=0.81, P<0.05). Detection of concavity in spontaneous flow-volume loops may help assess DH and exercise limitation in COPD.
运动期间的主动呼气可增加胸内压，导致慢性阻塞性肺疾病（COPD）患者呼气流量-容积环出现凹陷。我们研究了这种凹陷与动态肺过度充气（DH）之间的关系。17例COPD患者（第一秒用力呼气容积：占预计值的38±10%，全球慢性阻塞性肺疾病倡议组织（GOLD）3-4期）和12名健康受试者进行了蹬车测力计递增运动。使用几何方法（矩形面积比（RAR），《呼吸医学》，104(3):389-396, 2010年）逐次分析自发流量-容积环的呼气支。RAR低于0.5表明呼气支凹陷。通过连续吸气容量动作测定DH。17例患者中有5例在运动结束时几乎没有凹陷（RAR=0.52±0.04，低凹陷组）。12例患者在静息时存在凹陷，运动结束时RAR达到0.40±0.03（高凹陷组）。健康受试者未出现凹陷。运动结束时的RAR与静息时第一秒用力呼气容积占预计值百分比相关（R=0.81，P<0.05）。与低凹陷组和健康组相比，高凹陷组的运动强度、分钟通气量显著降低，呼吸困难更明显。DH与RAR呈负相关（R=0.81，P<0.05）。检测自发流量-容积环中的凹陷可能有助于评估COPD患者的DH和运动受限情况。
