Huh Jin Won, Seo Woo Jung, Ahn Jee Hwan, Lee Su Yeon, Suh Hee Jung, Seo Ga Jin, Kim Eun Young, Jang Min Kyung, Lim Chae-Man
Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Republic of Korea.
Front Med (Lausanne). 2025 May 9;12:1538832. doi: 10.3389/fmed.2025.1538832. eCollection 2025.
High-flow nasal cannula (HFNC) delivers a continuous, unidirectional high flow of oxygen (Uniflow) throughout the respiratory cycle. Despite its positive pressure effects in the nasopharynx, the persistent high flow during expiration imposes additional work of breathing and disrupts the patient's neural respiratory cycle. We devised a bi-level high-flow system (Biflow) allowing separate flow rate adjustments for inspiration and expiration.
We conducted a randomized crossover pilot study which we included healthy volunteer at ASAN Medical Center (April 2021 to June 2021). The data of 12 healthy volunteers (7 male, 5 female, average age 46.3 years) were analyzed. For Uniflow, flow settings of 30 (U30), 40 (U40), and 50 (U50) L/min were tested. In the Biflow, inspiratory flow rates were matched to the Uniflow settings, while expiratory flow rates varied from 10 to 30 L/min. The sequence of each flow (Uniflow vs. Biflow) was randomized and each flow setting was maintained for 3 min. Physiologic parameters, nasopharyngeal pressure-time product (N-PTP) as an energy cost proxy, end-expiratory lung impedance (EELI), and participant comfort were assessed.
Uniflow decreased respiratory rate and elongated expiratory time compared to natural breathing. However, these effects were less pronounced during Biflow. Compared with the Uniflow, both expiratory and inspiratory N-PTP were lower during the Biflow. Transcutaneous CO was lower during the Biflow compared with natural breathing or Uniflow. EELI did not differ between modes. All participants completed the study protocol without side effects.
In healthy participants, compared with the conventional HFNC (Uniflow), Biflow showed less interference with the natural respiratory cycle of the participants. Compared with Uniflow, energy cost occurring in the nasopharynx was lower during Biflow.
http://cris.nih.go.kr/cris/, identifier KCT0006100.
高流量鼻导管（HFNC）在整个呼吸周期中输送持续、单向的高流量氧气（单一流）。尽管其在鼻咽部有正压作用，但呼气期间持续的高流量会增加呼吸功并扰乱患者的神经呼吸周期。我们设计了一种双水平高流量系统（双流），允许分别调整吸气和呼气的流速。
我们在峨山医学中心（2021年4月至2021年6月）进行了一项随机交叉试点研究，纳入了健康志愿者。分析了12名健康志愿者（7名男性，5名女性，平均年龄46.3岁）的数据。对于单一流，测试了30（U30）、40（U40）和50（U50）L/分钟的流量设置。在双流中，吸气流量速率与单一流设置相匹配，而呼气流量速率在10至30 L/分钟之间变化。每种流量（单一流与双流）的顺序是随机的，每个流量设置保持3分钟。评估了生理参数、作为能量消耗指标的鼻咽压力-时间乘积（N-PTP）、呼气末肺阻抗（EELI）和参与者的舒适度。
与自然呼吸相比，单一流降低了呼吸频率并延长了呼气时间。然而，在双流期间这些影响不太明显。与单一流相比，双流期间呼气和吸气的N-PTP均较低。与自然呼吸或单一流相比，双流期间经皮二氧化碳较低。各模式之间EELI没有差异。所有参与者均完成了研究方案，无副作用。
在健康参与者中，与传统的HFNC（单一流）相比，双流对参与者自然呼吸周期的干扰较小。与单一流相比，双流期间鼻咽部产生的能量消耗较低。
