Reliability of an intravenous intermittent access port (saline lock) for obtaining blood samples for coagulation studies

Abstract

BACKGROUND: Patients admitted to rule out myocardial infarction often receive a heparin infusion that requires measurement of partial thromboplastin time every 6 to 8 hours until coagulation values stabilize. If the patient's acuity at admission does not necessitate placement of arterial or central catheters, insertion of an intermittent intravenous access port (saline lock) would decrease the need for frequent venipuncture. Many studies on obtaining blood samples via arterial and central catheters have been reported, but no reports have described the method of using a saline lock or the amount of blood discarded during that procedure. OBJECTIVE: To evaluate the efficacy of inserting a saline lock specifically for obtaining blood samples and to determine the amount of blood that must be discarded in order to obtain prothrombin and partial thromboplastin times that match the values from blood samples obtained via venipuncture. METHODS: Coagulation values determined with 2 consecutive blood samples obtained via the saline lock after the first 0.5 mL of blood withdrawn was discarded were compared with measurements determined with a blood sample obtained via venipuncture. RESULTS: Prothrombin and partial thromboplastin times were not significantly different among the 3 blood samples. CONCLUSION: The untoward effects of frequent venipunctures to obtain blood samples for measurement of prothrombin and partial thromboplastin times can be lessened by using an 18-gauge saline lock to obtain blood samples and discarding the first 0.5 mL of blood withdrawn before the samples for coagulation studies are collected.

A cross-sectional study to compare two blood collection methods: direct venous puncture and peripheral venous catheter

“…Several studies have analysed the concordance between the laboratory values obtained using DVP and PVC, most using PVCs fitted with saline syringes. 6 7 However, their equivalence has been little studied, sometimes with inadequate methodology, by contrasting means testing or the correlation coefficient, 19 and at other times using a small sample size. 20 21…”

“…For PVC collection, the intravenous fluid therapy line was first closed for 15 s, as was any medication with the PVC three-way valve, and a syringe was adapted, from which 4 mL of blood was discarded, as recommended in recent studies. 6 7 Thereafter, the syringe was changed by rotating the valve 1/8 to complete removal. Finally, the venous access was washed with 4 mL of saline solution and intravenous fluid therapy and/or any perfusions were restarted.…”

Comparison of Laboratory Values Obtained by Phlebotomy versus Saline Lock Devices

“…Prior research has examined the use of the peripheral IV as an option to obtaining blood draws. [5][6][7] The practice of obtaining blood via a saline lock [8][9][10][11] to decrease the number of venipunctures may be widespread, but the literature has no description of such use. Our study examined eight common laboratory tests (hematocrit, electrolytes, serum glucose, and cardiac enzymes) that frequently are repeated in the ED.…”

“…[5][6][7] Recent research has examined the use of saline lock devices (SLDs) as a mean of obtaining blood samples. [8][9][10][11] Past studies have used SLDs with running infusate, and many have looked specifically at isolated hematology, chemistry, or coagulation panels. 10 To the best of our knowledge, no studies have used needleless adapters as a means for obtaining samples from the existing SLD.…”

Comparisons of laboratory results between two blood samplings: Venipuncture versus peripheral venous catheter—A systematic review with meta‐analysis

“…Among 17 studies qualified for systematic review, seven studies (Arrants et al, 1999;Fincher, Strong, & Jackson, 1998;Hafner et al, 1993;Lancé et al, 2013;Mohler, Sato, Bobick, & Wise, 1998;Ortells-Abuye et al, 2014;Powers, 1999) were not qualified for meta-analysis because the studies did not provide sufficient statistical information. Ten studies (58.82%) out of these 17 studies were included for final meta-analysis (Table 2).…”