Theiler Lorenz, Schneeberg Fabian, Riedel Thomas, Kaiser Heiko, Riva Thomas, Greif Robert
Universitaetsklinik fur Anaesthesiologie und Schmerztherapie, Inselspital Bern, Bern, Switzerland.
Kantonsspital Graubunden, Chur, Switzerland.
BMJ Open. 2019 Jul 11;9(7):e025442. doi: 10.1136/bmjopen-2018-025442.
Apnoeic oxygenation using nasal high-flow oxygen delivery systems with heated and humidified oxygen has recently gained popularity in the anaesthesia community. It has been shown to allow a prolonged apnoea time of up to 65 min as CO increase was far slower compared with previously reported data from CO increase during apnoea. A ventilatory exchange due to the high nasal oxygen flow was proposed explaining that phenomenon. However, recent studies in children did not show any difference in CO clearance comparing high-flow with low-flow oxygen. To investigate this ventilatory exchange in adults, we plan this study comparing different oxygen flow rates and the increase of CO during apnoea. We hypothesise that CO clearance is non-inferior when applying low oxygen flow rates.
In this single-centre, single-blinded, randomised controlled trial, we randomly assign 100 patients planned for elective surgery to either control (oxygen 70 L/min, airway opened by laryngoscopy) or one of three intervention groups: oxygen 70, or 10, or 2 L/min, all with jaw thrust to secure airway patency. After anaesthesia induction and neuromuscular blockage, either one of the interventions or the control will be applied according to randomisation. Throughout the apnoea period, we will measure the increase of transcutaneous pCO (tcpCO) until any one of the following criteria is met: time=15 min, SpO <92%, tcpCO >10.67 kPa, art. pH <7.1, K >6.0 mmol/L. Primary outcome is the mean tcpCO increase in kPa/min.
After Cantonal Ethic Committee of Bern approval (ID 2018-00293, 22.03.2018), all study participants will provide written informed consent. Patients vulnerable towards hypoxia or hypercarbia are excluded. Study results will be published in a peer-reviewed journal and presented at national and international conferences.
This study was registered on www.clinicaltrials.gov (NCT03478774,Pre-results) and the Swiss Trial Registry KOFAM (SNCTP000002861).
使用带有加热和湿化氧气的鼻高流量输氧系统进行无呼吸氧合最近在麻醉学界受到欢迎。研究表明，与先前报道的无呼吸期间二氧化碳增加的数据相比，它可使无呼吸时间延长至65分钟，因为二氧化碳增加的速度要慢得多。有人提出，由于高鼻氧流量导致的通气交换可以解释这一现象。然而，最近在儿童中的研究表明，高流量氧与低流量氧在二氧化碳清除方面没有差异。为了研究成人中的这种通气交换，我们计划开展这项研究，比较不同的氧流量以及无呼吸期间二氧化碳的增加情况。我们假设，应用低氧流量时二氧化碳清除率不劣于高氧流量。
在这项单中心、单盲、随机对照试验中，我们将100例计划进行择期手术的患者随机分为对照组（氧流量70L/min，通过喉镜开放气道）或三个干预组之一：氧流量70、10或2L/min，均采用提颌法确保气道通畅。麻醉诱导和神经肌肉阻滞之后，根据随机分组情况应用其中一种干预措施或对照组措施。在整个无呼吸期间，我们将测量经皮二氧化碳分压（tcpCO）的升高，直至满足以下任何一项标准：时间=15分钟、脉搏血氧饱和度（SpO）<92%、tcpCO>10.67kPa、动脉血pH<7.1、血钾>6.0mmol/L。主要结局指标是tcpCO升高的平均值（kPa/分钟）。
获得伯尔尼州伦理委员会批准（编号2018-00293，2018年3月22日）后，所有研究参与者将提供书面知情同意书。排除对缺氧或高碳酸血症敏感的患者。研究结果将发表在同行评审期刊上，并在国内和国际会议上展示。
本研究已在www.clinicaltrials.gov（NCT03478774，预结果）和瑞士试验注册库KOFAM（SNCTP000002861）注册。
