Department of Anesthesiology and Critical Care Medicine, Hadassah-Hebrew University Medical Center, POB 12000, Jerusalem 91120, Israel.
Anesth Analg. 2011 Mar;112(3):593-6. doi: 10.1213/ANE.0b013e31820ad4ef. Epub 2011 Feb 8.
Noticeable changes in vital signs indicating hypovolemia occur only after 15% of the blood volume is lost. More sensitive variables (e.g., cardiac output, systolic pressure variation and its Δdown component) are invasive and difficult to obtain in the early phase of bleeding. Lately, a new technology for continuous optical measurements of minute-to-minute urine flow rates has become available. We performed a preliminary evaluation to determine whether urine flow can act as an early and sensitive warning of hypovolemia.
Eleven patients (ASA physical status I-II) undergoing posterior spine fusion surgery were studied prospectively. Study variables included heart rate, blood pressure (systolic and diastolic), systolic pressure variation and Δdown, minute urinary flow, hemoglobin, blood and urinary sodium, and creatinine in the blood and urine. Urine flow rate was measured using URINFO 2000™ (FlowSense Medical, Misgav, Israel). After recording baseline variables, 10 mL/kg of the patient's blood was shed and a second set of variables was recorded. Subsequently, hypovolemia was reversed by infusing colloid solution (hetastarch 6%) followed by recording a third set of variables. These 3 observations were then compared.
An average of 614 ± 143 mL (mean ± SD) of blood was shed. During phlebotomy, the mean urine flow rate decreased from 5.7 ± 8 mL/min to 1.07 ± 2.5 mL/min. Systolic blood pressure and hemoglobin also decreased. Δdown increased. After rehydration, urine flow, blood pressure, and Δdown values returned to baseline. The hemoglobin concentration decreased whereas other variables did not change significantly.
Urine flow rate is a dynamic variable that seems to be a reliable indicator of changes in blood volume. These results justify further investigation.
只有在失去 15%的血液量后，才能观察到表明血容量不足的生命体征明显变化。更敏感的变量（如心输出量、收缩压变异及其 Δdown 成分）是侵入性的，并且在出血的早期阶段难以获得。最近，一种用于连续测量每分钟尿量的新技术已经问世。我们进行了初步评估，以确定尿量是否可以作为血容量不足的早期和敏感预警。
11 名接受后路脊柱融合手术的患者（ASA 身体状况 I-II）进行前瞻性研究。研究变量包括心率、血压（收缩压和舒张压）、收缩压变异和 Δdown、每分钟尿量、血红蛋白、血液和尿液中的钠以及血液和尿液中的肌酐。使用 URINFO 2000™（FlowSense Medical，Misgav，以色列）测量尿量。记录基线变量后，采集患者 10mL/kg 的血液并记录第二组变量。随后，通过输注胶体溶液（羟乙基淀粉 6%）来逆转低血容量，然后记录第三组变量。然后比较这 3 组观察结果。
平均失血 614±143mL（均值±标准差）。在采血过程中，平均尿量从 5.7±8mL/min 降至 1.07±2.5mL/min。收缩压和血红蛋白也下降。Δdown 增加。在补液后，尿量、血压和 Δdown 值恢复到基线。血红蛋白浓度下降，而其他变量没有明显变化。
尿量是一个动态变量，似乎是反映血容量变化的可靠指标。这些结果证明了进一步研究的合理性。
