Consistency of remifentanil concentrations in propofol-Remifentanil infusions. A laboratory-based study.

BACKGROUND: There is increasing interest in two-agent single-pump intravenous infusions for anesthesia and sedation in pediatric patients. Propofol-remifentanil is one such mixture. The poor miscibility of such admixtures when remifentanil is added in very high concentrations and when the admixtures are maintained in static conditions has been demonstrated; however, these physiochemical properties have not been examined in clinically relevant concentrations or settings. AIM: To examine if propofol-remifentanil admixtures maintain consistent remifentanil delivery when mixed in clinically relevant remifentanil concentrations and subjected to the physical effects of an actively infusing, directly-engaged syringe driver system with an extension line, as occurs when propofol-remifentanil is administered to a patient. METHODS: A propofol 10 mg.ml-1 combined with remifentanil 5 mcg.ml-1 solution was run using a Paedfusor® propofol target-controlled infusion model for 10 kg and 20 kg children for 57 min at a target plasma concentration of 3 mcg.ml-1 through a 30 ml syringe, 180 cm minimum volume extension line, lever lock cannula, interlink injection site, and 22 g intravenous cannula into sample pots. Samples were taken at the completion of the loading bolus, 1 and 2 min postcompletion of loading bolus, and every 5 min thereafter. The remifentanil concentration in these samples was then assayed using chromatography. RESULTS: There was no difference in the concentration of remifentanil in the samples based on the duration of infusion to the endpoint of 1 h, or on the patient weight model used. The concentration remained 5 mcg.ml-1 +/- 0.5 mcg.ml-1 per sample. The measurement uncertainty for the assay at 0.5 mcg.ml-1 is +/- 0.2 mcg.ml-1 . CONCLUSION: The concentration of remifentanil was 5 mcg.ml-1 +/- 0.5 mcg.ml-1 and was consistent across 57 min of infusion, and two different pediatric weight profiles.

A biomarker of n-3 compliance in patients taking fish oil for rheumatoid arthritis.

Dietary fish oil supplements have been shown to have benefits in rheumatoid arthritis (RA), other inflammatory diseases, and in cardiovascular disease. As with any medical advice, variability will exist with regard to adherence and consequent biochemical or pharmacophysiologic effects. The aim was to explore the utility of plasma phospholipid EPA as a measure of n-3 PUFA intake and response to standardized therapeutic advice given in an outpatient or office practice setting, to increase dietary n-3 PUFA, including a fish oil supplement. Patients with early RA were given verbal and written advice to alter their dietary n-3 PUFA intake, including ingestion of 20 mL of bottled fish oil on juice daily. The advice included instructions to increase n-3 PUFA and to avoid foods rich in n-6 PUFA. Every 3 mon, blood samples were obtained for analysis of plasma phospholipid FA. Plasma phospholipid EPA was used as the primary index of n-3 PUFA intake. A diverse response was seen, with about one-third of patients achieving a substantial elevation of plasma phospholipid EPA over the 12-mon study period. A third had little change, with the remainder achieving intermediate levels. Data obtained longitudinally from individual patients indicated that substantial elevations of EPA (> 5% total plasma phospholipid FA) could be maintained for more than 3 yr. Plasma phospholipid EPA is a convenient measure of adherence to advice to take a dietary n-3 PUFA-rich fish oil supplement This measure may prove a useful adjunct to intention to treat analyses in determining the effect of dietary fish oil supplements on long-term outcomes in arthritis and other chronic inflammatory diseases. It may also provide a guide to the effectiveness of therapeutic and preventive messages designed to increase n-3 PUFA intake.