Dingley J, Foëx B A, Swart M, Findlay G, DeSouza P R, Wardrop C, Willis N, Smithies M, Little R A
Department of Anesthetics, University Hospital of Wales, South Glamorgan, UK.
Crit Care Med. 1999 Nov;27(11):2435-41. doi: 10.1097/00003246-199911000-00019.
To evaluate accuracy and repeatability of blood volume determinations made by the carbon monoxide method, using a ventilator-driven administration system.
Prospective within-patient comparison, using simultaneous measurements by two methods to determine accuracy. Prospective laboratory investigation in animals to estimate repeatability.
For accuracy: Nineteen ventilated critically ill patients in a university hospital intensive care unit. For repeatability: Six anesthetized, mechanically ventilated normovolemic pigs because this is impossible to perform in humans.
In the accuracy study, a small mass of carbon monoxide was administered via a closed breathing system and arterial blood samples were taken from existing cannulas. In the repeatability study, an intramuscular sedative was given, followed by an inhalational anesthetic induction and mechanical ventilation via a tracheal tube. Left axillary artery and external jugular vein cannulas were sited. Anesthesia was maintained using an intravenous infusion. Five sequential circulating hemoglobin and blood volume estimations were made using the carbon monoxide method.
The small carboxyhemoglobin increase produced by uptake of a small, known mass of carbon monoxide was used to estimate the circulating blood volume. Simultaneous measurement, using 51Cr-labeled red blood cells, was performed. Twenty measurements were made in 19 patients. The bias (mean difference between blood volume measurements by the two methods) was 397 mL (5.53 mL x kg(-1)) +/-415 mL (+/-5.95 mL x kg(-1)); the limits of agreement (mean difference +/-2 SD) were -433 mL and 1227 mL (-6.36 mL x kg(-1) and 17.42 mL x kg(-1)). Therefore, 95% of expected differences will lie between these limits. The mean blood volume was 75.8 mL x kg(-1) in the animals. The coefficient of variation of repeated estimates was 9.49%. Mean circulating hemoglobin mass was 7.31 mmol with a coefficient of variation of 10.18%. The mean hemoglobin concentration, by co-oximetry, was 5.014 mmol x L(-1), coefficient of variation, 2.99%.
This arrangement is a potential bedside method of estimating blood volume and circulating hemoglobin mass. We have rendered the technique more acceptable clinically by creating a ventilator-driven administration system.
使用呼吸机驱动给药系统，评估一氧化碳法测定血容量的准确性和可重复性。
前瞻性患者内比较，采用两种方法同时测量以确定准确性。在动物中进行前瞻性实验室研究以评估可重复性。
准确性研究：一所大学医院重症监护病房的19名接受机械通气的重症患者。可重复性研究：6只麻醉状态下、机械通气的血容量正常的猪，因为在人类中无法进行此项研究。
在准确性研究中，通过密闭呼吸回路给予少量一氧化碳，并从现有的插管采集动脉血样。在可重复性研究中，给予肌肉镇静剂，随后进行吸入麻醉诱导并通过气管导管进行机械通气。在左腋动脉和颈外静脉放置插管。使用静脉输注维持麻醉。使用一氧化碳法对循环血红蛋白和血容量进行5次连续测定。
通过摄取少量已知质量的一氧化碳所产生的少量碳氧血红蛋白增加量来估计循环血容量。同时使用51Cr标记的红细胞进行测量。对19名患者进行了20次测量。偏差（两种方法测量血容量的平均差值）为397 mL（5.53 mL×kg⁻¹）±415 mL（±5.95 mL×kg⁻¹）；一致性界限（平均差值±2标准差）为-433 mL和1227 mL（-6.36 mL×kg⁻¹和17.42 mL×kg⁻¹）。因此，95%的预期差值将落在这些界限之间。动物的平均血容量为75.8 mL×kg⁻¹。重复测量估计值的变异系数为9.49%。平均循环血红蛋白质量为7.31 mmol，变异系数为10.18%。通过共血氧测定法测得的平均血红蛋白浓度为5.014 mmol×L⁻¹，变异系数为2.99%。
这种方法是一种潜在的床旁估计血容量和循环血红蛋白质量的方法。我们通过创建呼吸机驱动给药系统使该技术在临床上更易于接受。
