Okamoto H, Hoka S, Kawasaki T, Okuyama T, Takahashi S
Department of Anaesthesiology and Critical Care Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Acta Anaesthesiol Scand. 1995 Jan;39(1):79-84. doi: 10.1111/j.1399-6576.1995.tb05596.x.
An intravenous administration of sodium bicarbonate (NaHCO3) forms excess CO2, resulting in an immediate increase in end-tidal carbon dioxide tension (PETCO2). We hypothesized that the time until PETCO2 reached a maximum, and the magnitude of the increase in PETCO2 are influenced by cardiac output and haemoglobin concentration, respectively. To test this hypothesis, we examined changes in PETCO2 following an intravenous administration of NaHCO3 at different levels of cardiac output and haemoglobin concentration. We administered 0.2 mmol.kg-1 of 8.4% NaHCO3 into the vena cava in 15 anesthetized dogs under mechanical ventilation of 20 breaths per min. Cardiac output was increased by dopamine infusion, and decreased by blood withdrawal under halothane anaesthesia. Haemoglobin concentrations were changed by haemodilution with hydroxyethyl starch. When control measurements were taken, time-max (the time until the increase in PETCO2 reached a maximum) was 4 +/- 0.2 breaths-time, and delta CO2-max (the magnitude of the increase in PETCO2) was 0.90 +/- 0.04 kPa (6.6 +/- 0.3 mmHg). Cardiac output was inversely correlated with time-max (r = 0.94, P < 0.0001), while it revealed a poor correlation with delta CO2-max. Haemoglobin concentration showed a significant correlation with delta CO2-max (r = 0.736, P < 0.005), but not with time-max. We concluded that the time course and the magnitude of changes in PETCO2 following intravenous administration of NaHCO3 reflect changes in cardiac output and haemoglobin concentration, respectively.
静脉注射碳酸氢钠（NaHCO₃）会产生过量的二氧化碳，导致呼气末二氧化碳分压（PETCO₂）立即升高。我们推测，PETCO₂达到最大值所需的时间以及PETCO₂升高的幅度分别受心输出量和血红蛋白浓度的影响。为了验证这一假设，我们在不同心输出量和血红蛋白浓度水平下静脉注射NaHCO₃后，检测了PETCO₂的变化。我们在每分钟20次呼吸的机械通气下，对15只麻醉犬经腔静脉注射0.2 mmol·kg⁻¹的8.4% NaHCO₃。通过输注多巴胺增加心输出量，在氟烷麻醉下通过放血减少心输出量。用羟乙基淀粉进行血液稀释来改变血红蛋白浓度。在进行对照测量时，时间最大值（PETCO₂升高达到最大值所需的时间）为4±0.2次呼吸时间，而二氧化碳变化最大值（PETCO₂升高的幅度）为0.90±0.04 kPa（6.6±0.3 mmHg）。心输出量与时间最大值呈负相关（r = 0.94，P < 0.0001），而与二氧化碳变化最大值相关性较差。血红蛋白浓度与二氧化碳变化最大值呈显著相关（r = 0.736，P < 0.005），但与时间最大值无关。我们得出结论，静脉注射NaHCO₃后PETCO₂变化的时间进程和幅度分别反映了心输出量和血红蛋白浓度的变化。
