麻醉猪在急性等容血液稀释过程中无法耐受失血性代偿。

Uncompensated blood loss is not tolerated during acute normovolemic hemodilution in anesthetized pigs.

作者信息

Schou H, Kongstad L, Perez de Sá V, Werner O, Larsson A

机构信息

Department of Anesthesia and Intensive Care, University Hospital, Lund, Sweden.

出版信息

Anesth Analg. 1998 Oct;87(4):786-94. doi: 10.1097/00000539-199810000-00009.

DOI:10.1097/00000539-199810000-00009

PMID:9768771

Abstract

UNLABELLED

Clinically, hemodilution to a hematocrit of 9% has been studied, but the effects of hypovolemia during this degree of hemodilution have not been elucidated. We studied the response to blood loss during extreme hemodilution and evaluated indicators of hypovolemia. Systemic and myocardial hemodynamics, oxygen transport, and blood lactate concentrations were measured in 12 anesthetized pigs exposed to a graded blood loss of 10, 20, 30, and 40 mL/kg. Six animals were hemodiluted (hematocrit 10.8% +/- 1.4%, mean +/- SD), and six animals served as controls (hematocrit 34.6% +/- 1.5%). Hemodilution decreased systemic oxygen delivery to 9.5 +/- 0.6 mL x kg(-1) x min(-1) (controls 21.7 +/- 3.9 mL x kg(-1) x min(-1)) (P < 0.01) despite a 31% increase in cardiac output. Systemic oxygen uptake was unchanged. Arterial lactate increased to 3.3 +/- 1.1 mM/L (controls 1.6 +/- 0.6 mM/L) (P < 0.05), and mixed venous oxygen saturation (SvO2) decreased to 38.2% + 4.8% (controls 68.6% +/- 2.9%) (P < 0.01). At a blood loss of 10 mL/kg, cardiac output continued to be greater in the hemodiluted animals (P < 0.01). Arterial blood pressure decreased to 61 +/- 8 mmHg (controls 84 +/- 18 mm Hg) (P < 0.05), whereas heart rate was unchanged. Systemic oxygen delivery decreased to 8.8 +/- 1.2 mL x kg(-1) x min(-1) (controls 14.1 +/- 2.5 mL x kg(-1) x min(-1)) (P < 0.01). Systemic oxygen uptake was maintained by a further increase in oxygen extraction, and SvO2 decreased to 29.7% +/- 7.3%, compared with 55.3% +/- 9.0% in controls (P < 0.01). Arterial lactate increased to 4.9 +/- 1.4 mM/L (controls 1.8 +/- 0.8 mM/L) (P < 0.01). Myocardial oxygen delivery and lactate uptake were unchanged. When the blood loss equaled 30 mL/kg, myocardial lactate production occurred, and two hemodiluted animals died of circulatory failure. Central venous and capillary wedge pressures changed minimally during the blood loss and did not differ between groups. We conclude that a decrease in arterial blood pressure and SvO2 were early signs of hypovolemia during hemodilution, whereas central venous pressure and pulmonary capillary wedge pressure were insensitive indicators.

IMPLICATIONS

Anesthetized pigs with extremely low hemoglobin levels (one third of normal) showed poor tolerance to blood loss >10 mL/kg. A decreasing arterial blood pressure, a decreasing oxygen saturation in the venous blood, and an increase in arterial blood lactate concentration were useful indicators of blood loss.

摘要

未加标注

临床上，已对血液稀释至血细胞比容为9%的情况进行了研究，但尚未阐明在这种程度的血液稀释过程中低血容量的影响。我们研究了极度血液稀释期间对失血的反应，并评估了低血容量的指标。在12只麻醉猪中，测量了全身和心肌血流动力学、氧输送以及血乳酸浓度，这些猪经历了10、20、30和40 mL/kg的分级失血。6只动物进行了血液稀释（血细胞比容10.8%±1.4%，平均值±标准差），6只动物作为对照（血细胞比容34.6%±1.5%）。尽管心输出量增加了31%，但血液稀释使全身氧输送降至9.5±0.6 mL·kg⁻¹·min⁻¹（对照组为21.7±3.9 mL·kg⁻¹·min⁻¹）（P<0.01）。全身氧摄取未改变。动脉血乳酸升至3.3±1.1 mM/L（对照组为1.6±0.6 mM/L）（P<0.05），混合静脉血氧饱和度（SvO₂）降至38.2% + 4.8%（对照组为68.6%±2.9%）（P<0.01）。在失血10 mL/kg时，血液稀释组动物的心输出量仍然更高（P<0.01）。动脉血压降至61±8 mmHg（对照组为84±18 mmHg）（P<0.05），而心率未改变。全身氧输送降至8.8±1.2 mL·kg⁻¹·min⁻¹（对照组为14.1±2.5 mL·kg⁻¹·min⁻¹）（P<0.01）。全身氧摄取通过进一步增加氧摄取得以维持，SvO₂降至29.7%±7.3%，而对照组为55.3%±9.0%（P<0.01）。动脉血乳酸升至4.9±1.4 mM/L（对照组为1.8±0.8 mM/L）（P<0.01）。心肌氧输送和乳酸摄取未改变。当失血量等于30 mL/kg时，心肌出现乳酸生成，2只血液稀释动物死于循环衰竭。失血期间中心静脉压和肺毛细血管楔压变化极小，且两组之间无差异。我们得出结论，动脉血压和SvO₂降低是血液稀释期间低血容量的早期迹象，而中心静脉压和肺毛细血管楔压是不敏感的指标。