Jakobsson Petter, Lindgren Madleine, Jakobsson Jan G
Faculty of Medicine, University of Lund, Lund, 221 00, Sweden.
Department of Anaesthesia & Intensive Care, Institution for Clinical Science, Karolinska Institutet, Danderyds University Hospital, Stockholm, 182 88 , Sweden.
F1000Res. 2017 Mar 29;6:389. doi: 10.12688/f1000research.11255.2. eCollection 2017.
Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia. We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA) and FLOW-i (Maquet, Solna, Sweden) in a test lung model. : We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1%) decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/min. to less than a minute at constant 4 L/min (17 ± 11 seconds), without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min. : Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.
现代麻醉工作站密封性良好，令人放心，且配备了有效的气体监测设备，因此为低流量/最低流量麻醉提供了良好条件。有效低流量麻醉的一个前提是能够在环路系统中快速增加和降低气体浓度，从而控制麻醉深度。我们研究了在固定新鲜气体流量和蒸发器设置的情况下，七氟醚在环路系统中的吸入和呼出情况。我们在一个测试肺模型中比较了两台现代麻醉工作站，即美国威斯康星州麦迪逊市通用电气公司的Aisys和瑞典索尔纳市迈柯唯公司的FLOW-i。我们发现，正如预期的那样，新鲜气体流量对七氟醚的吸入和呼出有重大影响。在新鲜气体流量恒定为300毫升/分钟且蒸发器设置为8%的情况下，达到稳定的环路1 MAC（2.1%）的吸入时间平均为547±83秒，而在新鲜气体流量为4升/分钟时，平均为38±6秒。所测试的两台工作站之间只有微小差异；在300和4升/分钟的流量下，Aisys的速度略快。将环路呼气末浓度从1 MAC进一步提高到1.5 MAC的时间同样与新鲜气体流量显著相关，在300毫升/分钟时为330±24秒，在恒定的4升/分钟时减少到不到一分钟（17±11秒），且与麻醉机无关。呼出也取决于新鲜气体流量，在7.5升/分钟时趋于平稳。环路系统的吸入和呼出表现出明显的新鲜气体依赖性，且Aisys和Flow-i之间略有不同。在新鲜气体流量恒定为2和4升/分钟的情况下，两台工作站均可在1.5分钟内使环路饱和度达到呼气末1 MAC或从1 MAC提高到-1.5 MAC。呼出在7.5升/分钟时趋于平稳。
