低氧、急性等容血液稀释及其联合作用对麻醉猪循环系统的影响。

Circulatory effects of hypoxia, acute normovolemic hemodilution, and their combination in anesthetized pigs.

作者信息

Schou H, Perez de Sá V, Sigurdardóttir M, Roscher R, Jonmarker C, Werner O

机构信息

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

出版信息

Anesthesiology. 1996 Jun;84(6):1443-54. doi: 10.1097/00000542-199606000-00021.

DOI:10.1097/00000542-199606000-00021

PMID:8669686

Abstract

BACKGROUND

Because hemodilution decreases the oxygen-carrying capacity of blood, it was hypothesized that severe hemodilution would decrease the tolerance to alveolar hypoxia.

METHODS

Hemodynamics, oxygen transport, and blood lactate concentrations were compared in ten pigs with normal hematocrit (33 +/- 4%), and ten hemodiluted pigs (hematocrit 11 +/- 1%; mean +/- SD) anesthetized with ketamine-fentanyl-pancuronium during stepwise decreases in inspired oxygen fraction (FIO2; 1.0, 0.35, 0.21, 0.15, 0.10, 0.05).

RESULTS

Median systemic oxygen delivery (DO2SY) became critical (the DO2SY value when arterial lactate exceeded 2.0 mmol.l-1) at 10.4 ml.kg-1.min-1 (range 6.9-16.1) in hemodiluted animals and at 11.8 ml.kg-1.min-1 (5.9-32.2) in animals with normal hematocrits (NS). The relationship between mixed venous oxygen saturation and arterial lactate values was less consistent and median critical mixed venous oxygen saturation was higher (P < 0.05) in the hemodiluted group (35%, range 21-64), than in animals with normal hematocrits (21%, 7-68%). In animals with normal hematocrit, decreasing FIO2 from 1.0 to 0.10 resulted in a decrease in DO2SY from 26.3 +/- 9.1 to 9.3 +/- 3.9 ml.kg-1.min-1 (P < 0.01). Cardiac output did not change, systemic oxygen extraction ratio increased from 0.23 +/- 0.08 to 0.68 +/- 0.13 (P < 0.01), and arterial lactate from 0.9 +/- 0.2 to 3.4 +/- 3.0 mmol.l-1 (P < 0.05). Cardiac venous blood flow, as measured by retrograde thermodilution, increased from 5.7 +/- 2.9 to 12.6 +/- 5.7 ml.kg-1.min-1 (P < 0.01). When FIO2 was reduced to 0.05, three animals became hypotensive and died. In the second group, hemodilution increased cardiac output and systemic oxygen extraction ratio (P < 0.01). Cardiac venous blood flow increased from 4.1 +/- 1.7 to 9.8 +/- 5.1 ml.kg-1.min-1 (P < 0.01), and cardiac venous oxygen saturation from 22 +/- 5 to 41 +/- 10% (P < 0.01). During the subsequent hypoxia, cardiac output and DO2SY were maintained until FIO2 = 0.15 (DO2SY = 10.1 +/- 3.3 ml.kg-1.min-1). Cardiac venous blood flow was then 18.5 +/- 10.7 ml.kg-1.min-1 (P < 0.01), but in spite of this, myocardial lactate production occurred. At FIO2 = 0.10 (DO2SY = 7.7 +/- 3.0 ml.kg-1.min-1), arterial lactate concentration increased to 8.5 +/- 2.3 mmol.l-1 (P < 0.01), and most animals became hypotensive. All hemodiluted animals died when FIO2 was decreased to 0.05 (P < 0.01 when compared to animals with normal hematocrit).

CONCLUSIONS

Systemic and myocardial lactate production occurred at similar systemic oxygen delivery rates in hemodiluted and nonhemodiluted animals. Mixed venous oxygen saturation may be a less reliable indicator of inadequate oxygen delivery during hemodilution.

摘要

背景

由于血液稀释会降低血液的携氧能力，因此有人推测严重血液稀释会降低对肺泡低氧的耐受性。

方法

对10只血细胞比容正常（33±4%）的猪和10只血液稀释的猪（血细胞比容11±1%；均值±标准差）进行比较，这些猪在氯胺酮-芬太尼-潘库溴铵麻醉下，逐步降低吸入氧分数（FIO₂；1.0、0.35、0.21、0.15、0.10、0.05），观察血流动力学、氧输送及血乳酸浓度变化。

结果

血液稀释动物的全身氧输送（DO₂SY）中位数在10.4 ml·kg⁻¹·min⁻¹（范围6.9 - 16.1）时达到临界值（即动脉血乳酸超过2.0 mmol·L⁻¹时的DO₂SY值），血细胞比容正常的动物在11.8 ml·kg⁻¹·min⁻¹（5.9 - 32.2）时达到临界值（无显著性差异）。混合静脉血氧饱和度与动脉血乳酸值之间的关系不太一致，血液稀释组的临界混合静脉血氧饱和度中位数较高（P < 0.05），为35%（范围21 - 64%），高于血细胞比容正常的动物（21%，7 - 68%）。在血细胞比容正常的动物中，将FIO₂从1.0降至0.10导致DO₂SY从26.3±9.1降至9.3±3.9 ml·kg⁻¹·min⁻¹（P < 0.01）。心输出量未改变，全身氧摄取率从0.23±0.08增至0.68±0.13（P < 0.01），动脉血乳酸从0.9±0.2增至3.4±3.0 mmol·L⁻¹（P < 0.05）。通过逆行热稀释法测量的心脏静脉血流量从5.7±2.9增至12.6±5.7 ml·kg⁻¹·min⁻¹（P < 0.01）。当FIO₂降至0.05时，3只动物出现低血压并死亡。在第二组中，血液稀释增加了心输出量和全身氧摄取率（P < 0.01）。心脏静脉血流量从4.1±1.7增至9.8±5.1 ml·kg⁻¹·min⁻¹（P < 0.01），心脏静脉血氧饱和度从22±5增至41±10%（P < 0.01）。在随后的低氧过程中，心输出量和DO₂SY维持到FIO₂ = 0.15（DO₂SY = 10.1±3.3 ml·kg⁻¹·min⁻¹）。此时心脏静脉血流量为18.5±10.7 ml·kg⁻¹·min⁻¹（P < 0.01），但尽管如此，仍出现心肌乳酸生成。在FIO₂ = 0.10（DO₂SY = 7.7±3.0 ml·kg⁻¹·min⁻¹）时，动脉血乳酸浓度增至8.5±2.3 mmol·L⁻¹（P < 0.01），大多数动物出现低血压。当FIO₂降至0.05时，所有血液稀释的动物均死亡（与血细胞比容正常的动物相比，P < 0.01）。