Intravenous catheter aspiration for obtaining basic analytes during intravenous infusion

doi:10.1016/S0196-0644(05)81705-6

Annals of Emergency Medicine

Volume 19, Issue 7, July 1990, Pages 789-792

https://doi.org/10.1016/S0196-0644(05)81705-6 Get rights and content

The aspiration of blood through a functioning IV line to obtain samples for laboratory analysis was evaluated. Thirty-eight emergency department patients were studied. Each had an 18-gauge IV catheter placed and then received a 100-mL bolus of either normal saline, lactated Ringer's, or 5% dextrose in water. Two samples of blood (“first aspirate” and “second aspirate”) were then aspirated from the IV catheter while one sample was obtained by venipuncture from the opposite arm (control). All three samples were then analyzed for CBC, electrolytes, BUN, creatinine, and glucose. Catheter aspiration succeeded in 30 of 38 attempts (79%). Three samples were hemolyzed, and five samples were unable to be fully aspirated. Results of paired t testing showed only occasional statistical significance and except for bicarbonate were not of clinical significance. This study suggests that catheter aspiration is a useful method of obtaining blood for certain laboratory tests in patients receiving IV infusions.

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Cited by (31)

Venipuncture versus peripheral catheter: Do infusions alter laboratory results?
2014, Journal of Emergency Nursing
Citation Excerpt :
These differences are probably because of the difficulty in obtaining samples free from environmental air contamination, with the resulting increase in pCO2 and loss of pO2. The studies of Corbo et al6 and Herr et al8 only showed differences for HCO3–, which was ascribed, in the case of Herr et al, to the under-filling of the laboratory tubes and, in the case in Corbo et al (although the differences had no clinical relevance), to a longer time of tourniquet application for samples from the VAD. Zlotowski et al14 also associate HCO3– alteration with the use of syringes for obtaining the samples and transferring them to the laboratory tubes, which could have given rise to a certain loss of carbon dioxide and, consequently, lower values of HCO3–.
Our aim was to evaluate the equivalence between analytic parameters from blood samples obtained from a saline solution lock device used for the infusion of drugs and those from venipuncture. In our emergency department, patients bearing a saline solution lock device have blood extracted by venipuncture to avoid possible contamination of the sample.
Adults from the emergency department with a saline solution lock device who required laboratory tests were selected as candidates for this cross-sectional observational study. Infusions were halted and flushed with 0.9% saline solution; 2 minutes later, 2 mL of blood was drawn and discarded, and the corresponding laboratory tubes were filled. Immediately after, another sample was withdrawn from the opposite extremity by venipuncture. Both samples were analyzed for hematology, biochemistry, venous blood gases, and coagulation parameters. Concordance was evaluated by use of the intraclass correlation coefficient with its 95% confidence intervals; Bland-Altman plots were used to illustrate the percentage of samples with differences exceeding 2 SDs. The mean differences were also checked to detect those exceeding the laboratory's systematic error.
An intraclass correlation coefficient of over 0.9 was achieved for all parameters except for pH, partial pressure of carbon dioxide, and partial pressure of oxygen. Differences of over 2 SDs were found in fewer than 10% of all parameters. None of them exceeded 3 SDs, except for pH and venous blood gases. All parameters showed differences below the laboratory's accepted systematic error except for pH and venous blood gases.
Blood samples extracted from a peripheral catheter with or without drug infusions are valid for the analysis of hematology, biochemistry, and coagulation parameters but not for venous blood gases. Nurses should know the benefits of using an existing peripheral catheter for drawing blood samples for laboratory analysis even when infusing commonly used drugs. Emergency nurses should consider collecting blood specimens from a venous access device regardless of the type of drug infusions administered, because it is a safe, simple, and fast technique, which is time efficient when treating patients with limited venous access sites. This procedure reduces patient discomfort and the risk of complications related to venipunctures.
Blood samples drawn from IV catheters have less hemolysis when 5-mL (vs 10-mL) collection tubes are used
2004, Journal of Emergency Nursing
It is common practice for emergency nurses to draw blood for laboratory analyses into vacuum tubes from newly inserted intravenous (IV) catheters, even though this technique has been associated with an increase in sample hemolysis. No clinical nursing studies have documented the effect of collection tube size on hemolysis of samples obtained via IV catheters.
To determine whether there is a difference in the hemolysis rate of blood samples drawn from IV catheters comparing 5-mL vacuum collection tubes to 10 mL vacuum collection tubes.
The study was conducted at the Emergency Department, Summa Health System, Akron, Ohio.
This study used a 4-group, 2-period crossover design randomly assigning the order of the vacuum tube drawn. With the crossover design, each patient served as his own control. Upon receiving orders to start an IV and draw blood, each of 12 study nurses obtained an envelope with 2 vacuum tubes randomly assigned as to which tube should be drawn first and which tube should be drawn second. Samples were analyzed for hemolysis using a Hitachi automated spectrophotometer as well as by visual inspection.
A linear mixed model was used to test the main hypothesis of vacuum tube type effects on hemolysis.
The 5-mL tubes showed significantly lower hemolysis than the 10 mL tubes (P <.0001) with a substantial effect size of .6 standard deviation units.
The risk of hemolyzing blood drawn from IV catheters can be significantly reduced by using 5-mL rather than 10-mL collection tubes.
Spurious values of serum electrolytes due to admixture of intravenous infusion fluids
2003, Journal of Emergency Medicine
Blood samples may be collected subsequent to the establishment of a working i.v. line. When collected incorrectly, such blood samples can yield spurious results of serum electrolyte and chemistry determinations. We present such a case and, further, show that serum chemistry values can be altered by contamination with i.v. fluids in the emergency patient and that such alterations can be of sufficient magnitude to affect treatment. Recommendations are given regarding aspiration of blood samples from working i.v. lines to minimize the risk of spurious measurements.
Accuracy of drawing blood through infusing intravenous lines
2001, Heart and Lung: Journal of Acute and Critical Care
Citation Excerpt :
It has also been demonstrated that using a smaller gauge IV catheter to obtain a blood specimen results in an increased incidence of hemolysis of the specimen resulting in erroneous laboratory values.15 It is important to note that carbon dioxide (CO2) levels have been found to vary during blood sampling from peripheral devices.3 However, these findings are suspected to be false as a result of inadequate filling of the blood tubes or extended time to processing while sitting at room temperature.16
Objective: To determine the usefulness of peripheral intravenous lines as an alternative route for obtaining blood samples. Design: Quasiexperimental. Setting: Wilford Hall Medical Center, a regional level I trauma center and military teaching hospital in San Antonio, Tex. Sample: A convenience sample of 64 subjects was enrolled between September 1997 and June 1998. Outcome Measures: Comparative analysis of a complete blood count and chemistry, using the patients as their own control, on the same Coulter Analyzer and Boelrringer Mannheim/Hitachi 747-200. Results: A total of 559 values were evaluated. Only 2.5% of the specimens exceeded the Clinical Laboratory Improvement Act standards. None of the values was clinically significant. Conclusion: Intravenous devices, if used properly, are reliable tools for blood specimen collection. They yield accurate analyte levels that may used in the treatment of patients. (Heart Lung^® 2001;30:66-73.)
Comparison of laboratory values obtained by means of routine venipuncture versus peripheral intravenous catheter after a normal saline solution bolus
2001, Annals of Emergency Medicine
Citation Excerpt :
Four studies1-3,7 concluded no significant differences, but clear clinical criteria were not reported. In fact, 2 of these studies, those of Mohler et al2 and Hanover et al,7 reported larger means than our venipuncture versus first aspirate mean of 0.17 mmol/L. Only Watson et al3 reported a smaller mean of 0.10 mmol/L, and Herr et al1 did not provide numeric data for potassium. All of these studies administered much less fluid, and only Herr et al and Hanover et al could report data for participants undergoing normal saline solution infusion (the latter being a drip at only 10 mL/h).
Study Objective: This study compares selected laboratory values of blood samples obtained by means of venipuncture and by means of a peripheral intravenous catheter after a normal saline solution bolus. Methods: In this prospective experimental study, each participant served as his or her own control. Hospital employees volunteered in the emergency department of a tertiary-care teaching hospital. Participants had a peripheral catheter placed in one upper extremity and received a 200-mL bolus of normal saline solution during a 10-minute period. After a 2-minute wait period, a 12-mL aspirate was withdrawn directly from the saline solution lock. A second 12-mL aspirate was also obtained. Concurrently, venipuncture was performed on the other upper extremity. All 3 samples were analyzed for CBC, electrolytes, blood urea nitrogen, creatinine, glucose, liver function tests, and prothrombin time/international normalized ratio (PT/INR). Limits of agreement analysis based on the definition of clinical equivalence, as determined by surveying residency-trained and board-certified emergency physicians, was used to compare the results of catheter aspirates with those of venipuncture aspirates. Results: Thirty-three volunteers participated. When comparing venipuncture versus first aspirate, 16 of the 19 laboratory tests evaluated had 99% agreement intervals that were within the predetermined definition of clinical equivalence. Potassium, bicarbonate, and glucose did not demonstrate clinical equivalence, and this difference persisted after a 12-mL discard volume. Conclusion: This study supports the use of blood samples obtained by means of aspiration from a peripheral catheter when testing for CBC, blood urea nitrogen, creatinine, liver function tests, and PT/INR in healthy-appearing patients. Catheter aspiration, when testing for electrolytes and glucose, may be reasonable in a more select group of patients. [Zlotowski SJ, Kupas DF, Wood GC. Comparison of laboratory values obtained by means of routine venipuncture versus peripheral intravenous catheter after a normal saline solution bolus. Ann Emerg Med. November 2001;38:497-504.]
Venipuncture versus central venous access: A comparison of methotrexate levels in pediatric leukemia patients
1999, Journal of Pediatric Oncology Nursing
Patients receiving methotrexate (MTX) therapy for treatment of acute lymphocytic leukemia (ALL) consistently have venipuncture MTX levels drawn twice during each hospitalization. The purpose of this study was to compare MTX levels drawn from central venous catheters (CVCs) with those drawn by venipuncture. A convenience sample of 14 pediatric patients was used, with a total of 33 peak levels and 33 trough level sample pairs collected. Venipuncture and CVC levels were compared by using the paired t-test and analyzing the peak and trough data pairs separately. Results confirmed there was no difference in MTX level results (peak, p = .502; trough, p = .114). However, the CVC trough levels would have changed clinical management for 5 of the 33 patients. Therefore, it is recommended that all MTX levels be drawn from the CVC but that trough MTX levels that would alter clinical management be verified by a venipuncture sample. This method will safely minimize the number of venipunctures for children with ALL.

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Brief reportIntravenous catheter aspiration for obtaining basic analytes during intravenous infusion

You can draw blood from the “IV arm” below the intravenous needle if you put a tourniquet in between

Am J Clin Pathol

Effect of drawing blood specimens proximal to an in-place but discontinued intravenous solution

Am J Clin Pathol

Brief report
Intravenous catheter aspiration for obtaining basic analytes during intravenous infusion