Blood Samples of Peripheral Venous Catheter or The Usual Way: Do Infusion Fluid Alters the Biochemical Test Results?

Design of an algorithm for the detection of intravenous fluid contamination in clinical laboratory samples

OBJECTIVES

Contamination of blood samples from patients receiving intravenous fluids is a common error with potential risk to the patient. Algorithms based on the presence of aberrant results have been described but have the limitation that not all infusion fluids have the same composition. Our objective is to develop an algorithm based on the detection of the dilution observed on the analytes not usually included in infusion fluids.

METHODS

A group of 89 cases was selected from samples flagged as contaminated. Contamination was confirmed by reviewing the clinical history and comparing the results with previous and subsequent samples. A control group with similar characteristics was selected. Eleven common biochemical parameters not usually included in infusion fluids and with low intraindividual variability were selected. The dilution in relation to the immediate previous results was calculated for each analyte and a global indicator, defined as the percentage of analytes with significant dilution, was calculated. ROC curves were used to define the cut-off points.

RESULTS

A cut-off point of 20 % of dilutional effect requiring also a 60 % dilutional ratio achieved a high specificity (95 % CI 91-98 %) with an adequate sensitivity (64 % CI 54-74 %). The Area Under Curve obtained was 0.867 (95 % CI 0.819-0.915).

CONCLUSIONS

Our algorithm based on the global dilutional effect presents a similar sensitivity but greater specificity than the systems based on alarming results. The implementation of this algorithm in the laboratory information systems may facilitate the automated detection of contaminated samples.

Reliability of blood tests taken from the peripheral intravenous catheter

We aimed to compare the reliability of laboratory blood tests using 2 sampling methods, via a peripheral venous catheter (PVC) vs direct venipuncture stab (DVS), we evaluated the effect of time elapsed since PVC insertion, PVC diameter, and administration of saline and/or antibiotic infusion through PVC on the blood test results. A prospective comparative study was conducted between May 2018 and July 2019. Patients aged ≥ 18 years and admitted to our department with a 20G/22G PVC inserted within the last 24 hours were enrolled. Blood samples were collected from each participant in the morning, and a second sample was drawn using PVC. Dependent variables included the percentage of hemolysis, failure rate, complete blood count, biochemical testing parameters, and coagulation functions. A total of 211 patients participated in the study. In total, 237 blood tests were conducted, of which 167 were performed on day 1 and the remaining on day 2, with a second blood sample collected from 26 patients on day 2. Twenty-one participants received 22G PVC, and 23 participants received active infusion. No significant differences were found in failure rates when each subgroup was compared with the primary day 1 group. The intraclass correlation coefficient indicated significant correlations among all the indices in all groups. Both blood sampling methods (PVC and direct venipuncture) can be used interchangeably for routine laboratory tests on days 1 and 2 after PVC insertion using 20G/22G PVC or infused PVC.

Is the Use of Pre-existing Peripheral Intravenous Cannula as an Alternative to Venipuncture for Blood Sampling Being Implemented?

Background

Blood tests are usually obtained by venipuncture which is an insertion of a needle into a vein. Since blood collection is frequently ordered, it contributes to the increased workload on healthcare professionals. Thus, utilization of previously inserted peripheral intravenous lines for blood collection is proposed to decrease the work burden.

Objective

The aim of the study was to make assessment of the awareness and practice of emergency medicine and intensive care unit staff regarding blood sampling via pre-existing peripheral line.

Methods

This is a cross-sectional study used a web-based and self-administered questionnaire. It distributed among emergency department and intensive care unit staff between November 2021 and February 2022.

Results

A total of 95 healthcare providers participated in the study. Most respondents were nurses (n=49, 51.5%) with 58.5% assigned to the intensive care unit. The overall mean awareness score was 1.74 out of 4 points with standard deviation of 1.29. Poor awareness was found among (n=65, 68.4%) and the remaining (n=30, 31.6%) had good awareness. Positive significant association has been observed between the level of awareness and practice (p=0.015). no significant difference was found between the emergency department and intensive care unit staff in terms of awareness level and practice.

Conclusion

Findings from the current study showed variation in participants' views, hence, nurses and other health care providers are left to use their personal preferences in deciding patient care. This highlights the need for establishing institutional policies regarding blood sampling via a pre-existing peripheral intravenous line.

Blood sampled from existing peripheral IV cannulae yields results equivalent to venepuncture: a systematic review

Objectives

To establish whether blood samples taken from used peripheral intravenous cannulae are clinically interchangeable with venepuncture.

Design

Systematic review. PubMed, Web of Science and Embase were searched for relevant trials.

Setting

Trials which compared blood samples from used peripheral intravenous cannulae to venepuncture and provided limits of agreement or data which allowed calculation of limits of agreement.

Participants

Seven trials with 746 participants. Blood tests included 13 commonly ordered biochemistry, haematology and blood gas measurements.

Main outcome measures

95% limits of agreement. Data were pooled using inverse variance weighting and compared to a clinically acceptable range estimated by expert opinion from previous trials.

Results

Limits of agreement for blood samples from used peripheral intravenous cannulae were within the clinically acceptable range for sodium, chloride, urea, creatinine and haematology samples. Limits of agreement for potassium were ±0.47 mmol/L which exceeded the clinically acceptable range. Peripheral intravenous cannula samples for blood gas analysis gave limits of agreement which far exceeded the clinically acceptable range.

Conclusions

Blood sampling from used peripheral intravenous cannulae is a reasonable clinical practice for haematology and biochemistry samples. Potassium samples from used peripheral intravenous cannulae can be used in situations where error up to ±0.47 mmol/L is acceptable. Peripheral intravenous cannula samples should not be used for blood gas analysis.

A Comparative Study of Blood Sampling From Venipuncture and Short Peripheral Catheters in Pediatric Inpatients

This prospective, comparative study examined blood test results, hemolysis rates, and patient perceptions related to 2 blood sampling methods in pediatric inpatients (N = 95). Blood specimens were drawn via venipuncture and a short peripheral catheter used for fluid administration. Results revealed no significant differences in potassium and glucose levels. No clinically significant difference in hemoglobin was noted. Hemolysis rates were 4% for venipuncture samples and 15% when drawn from peripheral catheters. One catheter became occluded after a blood draw. Patients/parents rated distress and dissatisfaction with venipuncture as significantly greater compared with short peripheral catheter blood sampling (P < .001).

Blood venous sample collection: Recommendations overview and a checklist to improve quality

The extra-analytical phases of the total testing process have substantial impact on managed care, as well as an inherent high risk of vulnerability to errors which is often greater than that of the analytical phase. The collection of biological samples is a crucial preanalytical activity. Problems or errors occurring shortly before, or soon after, this preanalytical step may impair sample quality and characteristics, or else modify the final results of testing. The standardization of fasting requirements, rest, patient position and psychological state of the patient are therefore crucial for mitigating the impact of preanalytical variability. Moreover, the quality of materials used for collecting specimens, along with their compatibility, can guarantee sample quality and persistence of chemical and physical characteristics of the analytes over time, so safeguarding the reliability of testing. Appropriate techniques and sampling procedures are effective to prevent problems such as hemolysis, undue clotting in the blood tube, draw of insufficient sample volume and modification of analyte concentration. An accurate identification of both patient and blood samples is a key priority as for other healthcare activities. Good laboratory practice and appropriate training of operators, by specifically targeting collection of biological samples, blood in particular, may greatly improve this issue, thus lowering the risk of errors and their adverse clinical consequences. The implementation of a simple and rapid check-list, including verification of blood collection devices, patient preparation and sampling techniques, was found to be effective for enhancing sample quality and reducing some preanalytical errors associated with these procedures. The use of this tool, along with implementation of objective and standardized systems for detecting non-conformities related to unsuitable samples, can be helpful for standardizing preanalytical activities and improving the quality of laboratory diagnostics, ultimately helping to reaffirm a "preanalytical" culture founded on knowledge and real risk perception.