Plotnikow Gustavo A, Thille Arnaud W, Vasquez Daniela N, Pratto Romina A, Quiroga Corina M, Andrich María E, Dorado Javier H, Gomez Ramiro S, D'Annunzio Pablo A, Scapellato José L, Intile Dante
Division of Respiratory Care, Intensive Care Unit, Anchorena Hospital, Buenos Aires, Argentina.
Centre Hospitalier Universitaire de Poitiers, INSERM CIC 1402 ALIVE, Université de Poitiers, Poitiers, France.
Respir Care. 2018 Aug;63(8):1016-1023. doi: 10.4187/respcare.06031. Epub 2018 Jun 26.
High-flow nasal cannula (HFNC) enables delivery of humidified gas at high flow while controlling the F . Although its use is growing in patients with acute respiratory failure, little is known about the impact of HFNC on lung volume. Therefore, we aimed to assess lung volume changes in healthy subjects at different flows and positions.
This was a prospective physiological study performed in 16 healthy subjects. The changes in lung volumes were assessed by measuring end-expiratory lung impedance by using electrical impedance tomography. All the subjects successively breathed during 5 min in these following conditions: while in a supine position without HFNC (T0) and 3 measurements in a semi-seated position at 45° without HFNC (T1), and with HFNC at a flow of 30 L/min (T2), and 50 L/min (T3).
Compared with the supine position, the values of end-expiratory lung impedance significantly increased with the subjects in a semi-seated position. End-expiratory lung impedance significantly increased after HFNC initiation in subjects in a semi-seated position and further increased by increasing flow at 50 L/min. When taking the end-expiratory lung impedance measurement in subjects in a semi-seated position (T1) as reference, the differences among the medians of global end-expiratory lung impedance were statistically significant ( < .001), which amounted to 1.05 units in T1; 1.12 units in T2; and 1.44 units in T3 ( < .05 for all comparisons, Wilcoxon test). The breathing frequency did not differ between the supine and semi-seated position (T0 and T1) but significantly decreased after initiation of HFNC and further decreased at high flow. T0 and T1 were not different ( = .13); whereas there was a statistically significant difference among T1, T2, and T3 ( < .05, post hoc test with Bonferroni correction).
In healthy subjects, the semi-seated position and the use of HFNC increased end-expiratory lung impedance globally. These changes were accompanied by a significant decrease in the breathing frequency.
高流量鼻导管（HFNC）能够在控制吸氧浓度的同时以高流量输送湿化气体。尽管其在急性呼吸衰竭患者中的应用日益增多，但关于HFNC对肺容积的影响却知之甚少。因此，我们旨在评估健康受试者在不同流量和体位下的肺容积变化。
这是一项针对16名健康受试者进行的前瞻性生理学研究。通过使用电阻抗断层扫描测量呼气末肺阻抗来评估肺容积的变化。所有受试者在以下条件下依次呼吸5分钟：仰卧位且不使用HFNC（T0），45°半卧位且不使用HFNC时进行3次测量（T1），以及使用HFNC且流量为30L/分钟（T2）和50L/分钟（T3）。
与仰卧位相比，半卧位时受试者的呼气末肺阻抗值显著增加。半卧位受试者开始使用HFNC后呼气末肺阻抗显著增加，并在50L/分钟的流量下进一步增加。以半卧位受试者（T1）的呼气末肺阻抗测量值为参考，总体呼气末肺阻抗中位数之间的差异具有统计学意义（P<0.001），T1为1.05单位；T2为1.12单位；T3为1.44单位（所有比较P<0.05，Wilcoxon检验）。仰卧位和半卧位（T0和T1）之间的呼吸频率无差异，但开始使用HFNC后显著降低，且在高流量时进一步降低。T0和T1无差异（P=0.13）；而T1、T2和T3之间存在统计学显著差异（P<0.05，采用Bonferroni校正的事后检验）。
在健康受试者中，半卧位和使用HFNC会使总体呼气末肺阻抗增加。这些变化伴随着呼吸频率的显著降低。
