Murthy Vydehi R, Escobar Hugo, Norberg Mike, Lachica Charisse I, Gratny Linda L, Sherman Ashley K, Truog William E, Manimtim Winston M
Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
Respir Care. 2017 May;62(5):595-601. doi: 10.4187/respcare.04858. Epub 2017 Feb 28.
The lower airway concentration of fractional exhaled nitric oxide (F) is unknown in children with chronic lung disease of infancy who have tracheostomy for long-term mechanical ventilation. We aimed to evaluate an online method of measuring F in a cohort of ventilator-dependent children with a tracheostomy and to explore the relationship between the peak F concentration (F peak) and the degree of respiratory support using the respiratory severity score.
We conducted a prospective cross-sectional study in 31 subjects who were receiving long-term respiratory support through a tracheostomy. We measured the F peak and F plateau concentration from the tip of the tracheostomy tube using a nitric oxide analyzer in subjects during a quiet state while being mechanically ventilated. We obtained 2 consecutive 2-min duration measurements from each subject. The F peak, exhaled NO output (equal to the F peak × minute ventilation), and pulmonary NO excretion (exhaled NO output/weight) were calculated and correlated with the respiratory severity score.
The median F peak was 2.69 ppb, and the median F plateau was 1.57 ppb. The coefficients of repeatability between the 2 consecutive measurements for F peak and F plateau were 0.74 and 0.59, respectively. The intraclass coefficient between subjects within the cohort was 0.988 (95% CI 0.975-0.994, < .001) for F peak and 0.991 (95% CI 0.982-0.996, < .001) for F plateau. We found that the F peak was directly correlated with minute ventilation, but we did not find a direct relationship between the F peak concentration, exhaled NO output, or pulmonary NO excretion and respiratory severity score.
F peak and plateau concentration can be measured online easily with a high degree of reliability and repeatability in infants and young children with a tracheostomy. F peak concentration from the lower airway is low and influenced by minute ventilation in children receiving mechanical ventilation.
对于因长期机械通气而行气管切开术的婴儿慢性肺部疾病患儿，呼出一氧化氮分数（F）在下呼吸道的浓度尚不清楚。我们旨在评估一种在线测量依赖呼吸机且行气管切开术患儿F的方法，并使用呼吸严重程度评分来探讨呼出一氧化氮峰值浓度（F峰值）与呼吸支持程度之间的关系。
我们对31名通过气管切开术接受长期呼吸支持的受试者进行了一项前瞻性横断面研究。在受试者机械通气安静状态下，使用一氧化氮分析仪从气管切开导管尖端测量F峰值和F平台期浓度。我们从每个受试者获取连续2分钟的测量值。计算F峰值、呼出一氧化氮输出量（等于F峰值×分钟通气量）和肺部一氧化氮排泄量（呼出一氧化氮输出量/体重），并与呼吸严重程度评分进行相关性分析。
F峰值中位数为2.69 ppb，F平台期中位数为1.57 ppb。F峰值和F平台期连续两次测量之间的重复性系数分别为0.74和0.59。队列中受试者之间F峰值的组内系数为0.988（95%CI 0.975 - 0.994，P <.001），F平台期为0.991（95%CI 0.982 - 0.996，P <.001）。我们发现F峰值与分钟通气量直接相关，但未发现F峰值浓度、呼出一氧化氮输出量或肺部一氧化氮排泄量与呼吸严重程度评分之间存在直接关系。
对于行气管切开术的婴幼儿，F峰值和平台期浓度可以通过在线方式轻松测量，具有高度的可靠性和重复性。接受机械通气患儿下呼吸道的F峰值浓度较低，且受分钟通气量影响。
