Anesthesia and Critical Care, Department of Pathophysiology and Transplantation, University of Milan, Via F. Sforza 35, 20122, Milan, Italy.
Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, Italy.
Crit Care. 2018 May 9;22(1):120. doi: 10.1186/s13054-018-2039-4.
The high-flow nasal cannula (HFNC) delivers up to 60 l/min of humidified air/oxygen blend at a temperature close to that of the human body. In this study, we tested whether higher temperature and flow decrease patient comfort. In more severe patients, instead, we hypothesized that higher flow might be associated with improved comfort.
A prospective, randomized, cross-over study was performed on 40 acute hypoxemic respiratory failure (AHRF) patients (PaO/FiO ≤ 300 + pulmonary infiltrates + exclusion of cardiogenic edema) supported by HFNC. The primary outcome was the assessment of patient comfort during HFNC delivery at increasing flow and temperature. Two flows (30 and 60 l/min), each combined with two temperatures (31 and 37 °C), were randomly applied for 20 min (four steps per patient), leaving clinical FiO unchanged. Toward the end of each step, the following were recorded: comfort by Visual Numerical Scale ranging between 1 (extreme discomfort) and 5 (very comfortable), together with respiratory parameters. A subgroup of more severe patients was defined by clinical FiO ≥ 45%.
Patient comfort was reported as significantly higher during steps at the lower temperature (31 °C) in comparison to 37 °C, with the HFNC set at both 30 and 60 l/min (p < 0.0001). Higher flow, however, was not associated with poorer comfort. In the subgroup of patients with clinical FiO ≥ 45%, both lower temperature (31 °C) and higher HFNC flow (60 l/min) led to higher comfort (p < 0.01).
HFNC temperature seems to significantly impact the comfort of AHRF patients: for equal flow, lower temperature could be more comfortable. Higher flow does not decrease patient comfort; at variance, it improves comfort in the more severely hypoxemic patient.
高流量鼻导管（HFNC）以接近人体温度的方式输送高达 60L/min 的加湿空气/氧气混合物。在本研究中，我们测试了更高的温度和流量是否会降低患者舒适度。在病情更严重的患者中，我们假设更高的流量可能与舒适度的提高有关。
对 40 例急性低氧性呼吸衰竭（AHRF）患者（PaO/FiO≤300+肺部浸润+排除心源性水肿）进行前瞻性、随机、交叉研究，使用 HFNC 进行支持。主要结局是评估 HFNC 输送时患者舒适度随流量和温度的增加而变化。两种流量（30 和 60L/min），每种流量分别与两种温度（31 和 37°C）相结合，随机应用 20 分钟（每位患者四个步骤），保持临床 FiO 不变。在每个步骤结束时，记录以下内容：使用视觉数字量表（范围 1 至 5，1 表示极度不适，5 表示非常舒适）评估舒适度，以及呼吸参数。通过临床 FiO≥45%定义更严重的患者亚组。
与 37°C 相比，在较低温度（31°C）下，HFNC 设置为 30 和 60L/min 时，患者舒适度报告显著更高（p<0.0001）。然而，更高的流量并不与较差的舒适度相关。在临床 FiO≥45%的患者亚组中，较低的温度（31°C）和较高的 HFNC 流量（60L/min）都导致了更高的舒适度（p<0.01）。
HFNC 温度似乎显著影响 AHRF 患者的舒适度：对于相等的流量，较低的温度可能更舒适。更高的流量不会降低患者的舒适度；相反，它提高了更严重低氧血症患者的舒适度。
