Hypoglycemia caused by siphoning of an insulin infusion.

STUDY OBJECTIVE: To determine--through reconstruction of a clinical situation in which a syringe filled with insulin was removed from the syringe pump, placed above the patient, then emptied into the patient--the different physical forces at work, and to examine the height of the syringe (and thus the hydrostatic force) necessary to move the plunger. DESIGN: Prospective study. SETTING: Research laboratory of a university. MEASUREMENTS: The clinical situation was simulated using eight 50-mL and eight 20-mL syringes. A pressure transducer, placed between the syringe and the extension tubing, measured the pressure difference over the extension tubing. The Poiseuille equation of the viscous resistance was used to calculate flow. MAIN RESULTS: The mean height needed for initiation of flow in the 50-mL syringes was 76 cm (range, 60-90 cm). In the 20-mL syringes, no flow could be generated up to heights of 200 cm. There was a large variability in the height and time required to generate flow in apparently identical syringes, probably due to differences in the static sticking of the plunger to the barrel. CONCLUSIONS: Studies testing the effect of siphoning using one syringe cannot be interpreted reliably. Smaller syringes are safer to avoid siphoning.

Levobupivacaine-sufentanil with or without epinephrine during epidural labor analgesia.

In a prospective, randomized, double-blind study, we investigated whether epinephrine increased the efficacy of levobupivacaine and sufentanil during epidural labor analgesia. Seventy term parturients received an epidural injection of levobupivacaine 0.125% and sufentanil 0.75 microg/mL with or without 1:800,000 epinephrine. After an initial dose of 10 mL, a patient-controlled analgesia pump was started. Total and hourly drug consumption, pain scores using the visual analog scale, sensory and motor block, duration of labor, vital variables, maternal and neonatal outcome, and side effects were compared. If the parturients experienced insufficient pain relief during the study, even after a rescue dose of 10 mL, they were excluded from further study and received 10 mL of bupivacaine 0.125% and sufentanil 0.75 microg/mL with 1:800,000 epinephrine. Hourly drug consumption, rescue dosing, and pain scores at 15 min and 20 min were lower in the epinephrine group. The incidence of motor block and duration of the second stage of labor tended to be higher in the epinephrine group and were associated with lower Apgar scores at 1 and 5 min. These findings suggest that the addition of epinephrine intensifies the effects of epidural levobupivacaine and sufentanil but may cause more motor block.