Volume of blood required to obtain central venous catheter blood cultures in infants and children

Performance of 3 mL versus 5 mL Discarded Volume for Blood Sampling from Central Venous Access Device

Background  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. Patients and Methods  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. Statistical Analysis Used  Paired t -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. Results  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. Conclusions  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.

Comparing Two Methods to Obtain Blood Specimens From Pediatric Central Venous Catheters

The purpose of this study was to test agreement in blood values obtained from a discard method and a push-pull method in samples from central venous catheters in pediatric patients. The discard method causes blood loss beyond what is necessary for blood testing and increases potential for infection each time the central venous catheter is entered. Twenty-eight children ranging in age from 6 months to 12 years were enrolled in the study. A research protocol was developed to pair the 2 methods of blood collection for each sample. The Bland-Altman method was used to test agreement on each blood value for each paired sample. Of the 438 pairs of measured blood values, 420 (95.9%) fell within the limits of agreement. Nurses reported no difficulty in using the push-pull technique to obtain any samples. The push-pull method of obtaining blood specimens from pediatric central venous catheters should be considered. It can eliminate blood loss through discard and can reduce infection because it reduces the number of times a catheter is entered.

Diagnosis and treatment of catheter-related infections in paediatric oncology: an update

Otherwise unexplained clinical signs of infection in patients with long-term tunnelled or totally implanted central venous access devices (CVADs) are suspected to be CVAD-associated. Diagnostic methods include catheter swabs, blood cultures and cultures of the catheter tip or port reservoir. In the case of a suspected CVAD-related bloodstream infection in paediatric oncology patients, in-situ treatment without prompt removal of the device can be attempted. Removal of the CVAD should be considered if bacteraemia persists or relapses > or = 72 h after the initiation of (in-vitro effective) antibacterial therapy administered through the line. Timely removal of the device is also recommended if the patient suffers from a complicated infection, or if Staphylococcus aureus, Pseudomonas aeruginosa, multiresistant Acinetobacter baumannii or Candida spp. are isolated from blood cultures. Duration of therapy depends on the immunological recovery of the patient, the pathogen isolated and the presence of related complications, such as thrombosis, pneumonia, endocarditis and osteomyelitis. Antibiotic lock techniques in addition to systemic treatment are beneficial for Gram-positive infections. Although prospectively controlled studies are lacking, the concomitant use of urokinase locks and taurolidine secondary prophylaxis seem to favour catheter salvage.

Central venous catheters versus peripheral veins for sampling blood levels of commonly used drugs

BACKGROUND

Our objective was to compare the accuracy of drug levels in blood samples obtained from central venous catheters with those from peripheral blood samples taken to monitor various drug levels.

METHODS

Pediatric patients with central venous catheters receiving aminoglycosides, vancomycin, or cyclosporine had central and peripheral blood samples obtained within 5 minutes of each other and analyzed simultaneously. We ascertained how well blood levels from central venous catheters compared with those from peripheral blood (the criterion standard).

RESULTS

There were no clinically significant differences between central and peripheral values for amikacin, gentamicin, tobramycin, and vancomycin (both peaks and troughs). Preliminary data indicated that oral cyclosporine can be monitored via central venous catheter. In contrast, there was poor agreement between peripheral and central values when cyclosporine was administered by IV.

CONCLUSIONS

Amikacin, gentamicin, tobramycin, vancomycin, and probably oral cyclosporine can be monitored accurately via central venous catheter. In contrast, IV cyclosporine should be monitored via peripheral blood.