Lalthanthuami H T, Kumari M J, Venkateswaran R, Lakshmi P R, Ramamoorthy Lakshmi
Department of Medical Surgical Nursing, College of Nursing, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India.
College of Nursing, JIPMER, Puducherry, India.
J Lab Physicians. 2021 Jun;13(2):112-117. doi: 10.1055/s-0041-1726669. Epub 2021 Jun 17.
Central venous access devices (CVAD) are an essential part of safe practices in critical care, which enable effective venous access and help in avoiding repeated venipuncture. Discard method is widely practiced for blood sampling. A single occasion of blood sampling may cause minimal blood loss; however, the cumulative volume sequential sampling may become clinically significant. The study aims to reduce diagnostic blood loss, ensuring that the subsequent blood sample is not diluted or contaminated by residual intraluminal fluid. Within-subjects comparative design was adopted for 64 adult patients in the medical intensive care unit of a tertiary hospital. Two blood samples, using 3 mL and 5 mL discarded volume methods, were collected from each patient. Six serum parameters were measured on each of the paired samples and compared. Paired -test and Wilcoxon signed rank test were used for comparing the two methods. Bland-Altman plot analysis and intraclass correlation were used for clinically meaningful analysis. When tested for fixed bias, there is no statistically significant difference between the methods. Potassium and creatinine levels showed significant proportional bias. The agreement limits of sodium, potassium, creatinine, and direct bilirubin were outside the clinically accepted interval, but the proportion of samples outside these intervals was less than 10%. All serum parameters showed excellent reliability, except for sodium which demonstrated good reliability. The practice of discarding 3 mL of blood for discard method is suggested, instead of the standard 5 mL to reduce iatrogenic blood loss. Thus, nurses in critical care are uniquely positioned to limit the diagnostic blood loss while obtaining blood samples.
中心静脉通路装置（CVAD）是重症监护安全操作的重要组成部分，它能实现有效的静脉通路，并有助于避免反复静脉穿刺。弃血法在血液采样中广泛应用。单次血液采样可能导致最小程度的失血；然而，累积的连续采样血量可能在临床上变得显著。本研究旨在减少诊断性失血，确保后续血样不被残留管腔内液体稀释或污染。
一家三级医院的内科重症监护病房对64名成年患者采用了受试者内比较设计。从每位患者采集两份血样，分别采用弃血3 mL和5 mL的方法。对每对样本测量六项血清参数并进行比较。
采用配对t检验和Wilcoxon符号秩检验比较两种方法。使用Bland-Altman图分析和组内相关性进行有临床意义的分析。
在检验固定偏倚时，两种方法之间无统计学显著差异。钾和肌酐水平显示出显著的比例偏倚。钠、钾、肌酐和直接胆红素的一致性界限超出临床可接受区间，但超出这些区间的样本比例小于10%。除钠显示出良好的可靠性外，所有血清参数均显示出极好的可靠性。
建议采用弃血3 mL的方法，而非标准的5 mL，以减少医源性失血。因此，重症监护病房的护士在采集血样时处于独特的位置，能够限制诊断性失血。
