Verger Nicolas, Arigliani Michele, Raywood Emma, Duncan Julie, Negreskul Yulia, Bush Andrew, Aurora Paul
Respiratory, Critical Care and Anaesthesia Section, Infection Inflammation and Immunity Programme, UCL Great Ormond Street Institute of Child Health, London, UK.
Division of Pediatrics, Department of Medicine, University Hospital of Udine, Udine, Italy.
Pediatr Pulmonol. 2020 Sep;55(9):2315-2322. doi: 10.1002/ppul.24863. Epub 2020 Jun 1.
S is a multiple breath washout (MBW) index that measures convection-dependent ventilation inhomogeneity (CDI) arising within conductive airways, but the calculation method is unreliable in subjects with advanced cystic fibrosis (CF) lung disease. A new CDI index, S *, has been proposed for use in adults with CF and moderate to severe ventilation inhomogeneity. We aimed to evaluate the most appropriate CDI index in children and adolescents with CF and various degrees of inhomogeneity, and from that the most appropriate diffusion-convection-interaction index (S or S *).
S , S and the alternative indices, S *, and S * were retrospectively calculated in subjects with CF aged 3 to 18 years and age-matched controls, who underwent sulfur hexafluoride MBW between 2003 and 2015. The upper limit of normal was based on 95th percentile of the control population.
One hundred and twenty-seven subjects with CF (44% male; mean age ± SD: 7.5 years ± 4.9) and 94 controls (53% male; 7.9 years ± 5.1) were included in the final analysis. All measures of ventilation inhomogeneity were significantly higher in children with CF. As predicted, S reached a maximum value at lung clearance index (LCI) values of approximately 9. In subjects with LCI ≥ 9 S * showed good correlation with LCI, whilst S had no relationship with LCI (Spearman rank correlation S */LCI, 0.49; P < .01; S /LCI, -0.068; P = .46). In subjects with mild disease (LCI < 9) S was more frequently abnormal than S * (37% vs 16%; P = .01).
S and S are sensitive indices of early regional inhomogeneity, but are of no value when LCI ≥ 9. In these subjects, S * & S * are potential alternatives.
S是一种多次呼吸洗脱（MBW）指数，用于测量传导气道内产生的对流依赖性通气不均匀性（CDI），但在晚期囊性纤维化（CF）肺病患者中，其计算方法不可靠。一种新的CDI指数S已被提出用于患有CF且通气不均匀性为中度至重度的成年人。我们旨在评估CF儿童和青少年中不同程度不均匀性时最合适的CDI指数，并由此评估最合适的扩散-对流-相互作用指数（S或S）。
对2003年至2015年间接受六氟化硫MBW检查的3至18岁CF患者及年龄匹配的对照者，回顾性计算S、S以及替代指数S和S。正常上限基于对照人群的第95百分位数。
最终分析纳入了127例CF患者（44%为男性；平均年龄±标准差：7.5岁±4.9）和94例对照者（53%为男性；7.9岁±5.1）。CF儿童的所有通气不均匀性测量值均显著更高。如预期的那样，S在肺清除指数（LCI）值约为9时达到最大值。在LCI≥9的受试者中，S与LCI显示出良好的相关性，而S与LCI无相关性（斯皮尔曼等级相关性S/LCI，0.49；P<0.01；S/LCI，-0.068；P=0.46）。在轻度疾病（LCI<9）的受试者中，S比S*更常出现异常（37%对16%；P=0.01）。
S和S是早期区域不均匀性的敏感指标，但当LCI≥9时无价值。在这些受试者中，S和S是潜在的替代指标。
