Bengtson J P, Arnestad J P, Bengtsson J, Bengtsson A, Stenqvist O
Abteilung für Anästhesiologie und Intensivmedizin, Sahlgrens Krankenhaus, Universitätsklinik Göteborg, Schweden.
Anaesthesist. 1993 May;42(5):273-9.
The estimation of oxygen consumption and carbon dioxide elimination is essential for predicting the metabolic activity and needs of any patient having anaesthesia. During anaesthesia oxygen consumption can be measured and compared to a predicted value. However, oxygen uptake is affected by anaesthetic agents, which complicates the interpretation of measured oxygen uptake rate. The purpose of this study was to investigate whether there are any differences in respiratory gas exchange during anaesthesia with enflurane and isoflurane and also to assess the effects of spontaneous versus controlled ventilation. METHODS. Forty orthopedic patients were randomized to enflurane or isoflurane anaesthesia in nitrous oxide with either spontaneous or controlled ventilation. A fresh low-gas-flow technique was used. Inspiratory oxygen and end-tidal carbon dioxide concentrations and expiratory minute ventilation were measured in a circle absorber system between the y-piece and the endotracheal tube with a sampling analyser. Between the mixing box and the absorption canister, carbon dioxide concentration was continuously measured. The carbon dioxide elimination was calculated from mixed expired concentration and expiratory minute ventilation. Excess gas was collected every 10 min in a non-permeable mylar plastic bag connected to the excess valve. The excess gas flow was calculated and the oxygen uptake rate was assumed to be the difference between the oxygen fresh gas flow and the oxygen excess gas flow. RESULTS. The grand mean oxygen uptake rate was 2.5 ml.kg-1 x min-1 or 100 ml.min-1 x m-2. There were no statistically significant differences in oxygen uptake between enflurane and isoflurane anaesthesia or between spontaneous and controlled ventilation. The mean oxygen uptake rate at 10 min was between 2.0 and 2.2 ml.kg-1 x min-1 in all groups. At 30 min the mean oxygen uptake rates were 2.6 to 2.8 ml.kg-1 x min-1. Carbon dioxide elimination was closely associated with expired minute ventilation, with a carbon dioxide excretion of about 30 ml per litre gas exhaled, irrespective of ventilatory mode employed.
估计耗氧量和二氧化碳排出量对于预测任何接受麻醉的患者的代谢活动和需求至关重要。在麻醉期间，可以测量耗氧量并与预测值进行比较。然而，氧摄取受麻醉剂影响，这使得对所测氧摄取率的解释变得复杂。本研究的目的是调查在使用安氟醚和异氟醚麻醉期间呼吸气体交换是否存在差异，并评估自主通气与控制通气的效果。方法：40例骨科患者被随机分为接受安氟醚或异氟醚麻醉，同时吸入氧化亚氮，采用自主通气或控制通气。使用新鲜低流量技术。用采样分析仪在Y形接头和气管内导管之间的循环吸收系统中测量吸气氧浓度、呼气末二氧化碳浓度和呼气分钟通气量。在混合箱和吸收罐之间连续测量二氧化碳浓度。根据混合呼出气体浓度和呼气分钟通气量计算二氧化碳排出量。每隔10分钟将多余气体收集在连接到废气阀的不可渗透的聚酯薄膜塑料袋中。计算多余气体流量，并假定氧摄取率为新鲜氧气流量与多余氧气流量之差。结果：总平均氧摄取率为2.5 ml·kg-1·min-1或100 ml·min-1·m-2。安氟醚和异氟醚麻醉之间或自主通气与控制通气之间的氧摄取在统计学上无显著差异。所有组在10分钟时的平均氧摄取率在2.0至2.2 ml·kg-1·min-1之间。在30分钟时，平均氧摄取率为2.6至2.8 ml·kg-1·min-1。二氧化碳排出与呼出分钟通气量密切相关，无论采用何种通气模式，每升呼出气体的二氧化碳排出量约为30 ml。
