Variability in the concentrations of intravenous drug infusions prepared in a critical care unit.

OBJECTIVE: To quantify the variability in the concentration of drug infusions prepared on an intensive care unit and establish whether there was a relationship between the quality of syringe labeling and drug preparation. DESIGN: Audit carried out over 3 weeks in May 2006 and completed in May 2007. SETTING: The adult neurosciences critical care unit of a UK university teaching hospital. INTERVENTIONS: Daily collections of discarded syringes containing midazolam, insulin, norepinephrine, dopamine, potassium or magnesium. MEASUREMENTS AND RESULTS: Residual solutions in the syringes were sampled and the concentrations measured. Syringe labels were inspected and awarded a score for labeling quality based on an 11-point scale. A total of 149 syringes were analyzed. Six of the magnesium syringes contained 4-5 times too much Mg(2+), presumably because of confusion about converting millimoles to grams. The majority of the other infusions differed from the expected concentration by more than 10%. Magnesium infusions were least likely to be properly labeled (p= 0.012), and there was a positive correlation between quality of syringe labeling and drug preparation (p=0.002). After the introduction of a new electrolyte prescription chart, magnesium and potassium preparation significantly improved but there was still substantial variability. CONCLUSIONS: These findings present a strong argument for the use of pre-prepared syringes or standardized drug preparation and labeling systems. They also highlight once again the difficulties healthcare professionals encounter when dealing with different ways of expressing drug concentrations.

The MHP36 line of murine neural stem cells expresses functional CXCR1 chemokine receptors that initiate chemotaxis in vitro.

Chemokines help to establish cerebral inflammation after ischemia, which comprises a major component of secondary brain injury. The CXCR4 chemokine receptor system induces neural stem cell migration, and hence has been implicated in brain repair. We show that CXCR1 and interleukin-8 also stimulate chemotaxis in murine neural stem cells from the MHP36 cell line. The presence of CXCR1 was confirmed by reverse transcriptase PCR and immunohistochemistry. Interleukin-8 evoked intracellular calcium currents, upregulated doublecortin (a protein expressed by migrating neuroblasts), and elicited positive chemotaxis in vitro. Therefore, effectors of the early innate immune response may also influence brain repair mechanisms.

Doctors' confusion over ratios and percentages in drug solutions: the case for standard labelling.

The different ways of expressing concentrations of drugs in solution, as ratios or percentages or mass per unit volume, are a potential cause of confusion that may contribute to dose errors. To assess doctors' understanding of what they signify, all active subscribers to doctors.net.uk, an online community exclusively for UK doctors, were invited to complete a brief web-based multiple-choice questionnaire that explored their familiarity with solutions of adrenaline (expressed as a ratio), lidocaine (expressed as a percentage) and atropine (expressed in mg per mL), and their ability to calculate the correct volume to administer in clinical scenarios relevant to all specialties. 2974 (24.6%) replied. The mean score achieved was 4.80 out of 6 (SD 1.38). Only 85.2% and 65.8% correctly identified the mass of drug in the adrenaline and lidocaine solutions, respectively, whilst 93.1% identified the correct concentration of atropine. More would have administered the correct volume of adrenaline and lidocaine in clinical scenarios (89.4% and 81.0%, respectively) but only 65.5% identified the correct volume of atropine. The labelling of drug solutions as ratios or percentages is antiquated and confusing. Labelling should be standardized to mass per unit volume.