Interpretation of the large red-and-white visual analog scale by children compared with adults.

The red-and-white visual analog scale (VAS) is a modification of the traditional VAS. The purpose of this study was to compare how children of various ages and adults rate their anticipatory pain intensity on the red-and-white VAS. One hundred children were interviewed as part of the anesthesiologist's preoperative visit before elective eye surgery. For comparison, 50 healthy adults were interviewed in a similar manner. The medians and ranges describing mild, moderate, and severe pain, or pain intensity at which medicine would be requested, did not differ between preschool children, young schoolchildren, and adolescents or between children and adults. The median score of anticipated need for pain medication was 50% of the maximum for children.

Pharmacokinetic-pharmacodynamic relationship of dobutamine and heart rate, stroke volume and cardiac output in healthy volunteers.

BACKGROUND AND OBJECTIVE: Dobutamine causes an increase in cardiac output (CO) by augmenting stroke volume (SV) through enhanced left ventricular contractility and by decreasing systemic vascular resistance. However, in some patients, the dominant mechanism by which dobutamine improves left ventricular performance is an increase in the subject's heart rate (HR). We therefore decided to evaluate the pharmacokinetic-pharmacodynamic relationship of dobutamine plasma concentrations and heart rate, SV and CO in healthy volunteers. METHODS: We enrolled 23 subjects who received dobutamine at a dose of 2.5, 5 and 10 microg/kg/min for three consecutive periods of 60 minutes each. Dobutamine plasma concentrations were determined from 22 blood samples drawn during each study session. Echocardiography was used to measure CO before administration of dobutamine and once during each infusion period. RESULTS: There was a clear linear relationship between dobutamine plasma concentrations and CO (r(2) = 0.628; p < 0.001). In most subjects, HR remained stable at dobutamine plasma concentrations produced by the lowest infusion rate but increased markedly thereafter so that overall there was a linear relationship between dobutamine plasma concentrations and HR (r(2) = 0.540; p < 0.001). However, SV increased significantly at the dobutamine plasma concentrations produced by the lowest infusion rate but remained mostly stable or even decreased thereafter. Although clinically slight, the overall increase in SV was statistically significant (r(2) = 0.062; p < 0.05). CONCLUSION: Low plasma concentrations of dobutamine resulted in an increase in CO almost solely due to improved left ventricular contractility. However, at higher plasma concentrations of dobutamine, SV remained stable or even decreased, and the linear increase in CO was entirely based on increased HR.

Localization of local anesthetic solution by magnetic resonance imaging.

PURPOSE: The aim of this study was to examine the distribution of local anesthetic solution by magnetic resonance imaging (MRI) after combined peribulbar and retrobulbar, superomedial retrobulbar, and sub-Tenon's injection in relation to clinical akinesia. DESIGN: Randomized clinical trial. PARTICIPANTS: Fifteen patients scheduled for cataract surgery, 5 patients in each group. METHODS: Five patients received combined peribulbar and retrobulbar anesthesia, 5 patients received superomedial retrobulbar injection, and 5 patients had sub-Tenon's injection, all with a combination of bupivacaine 0.75%, lidocaine 2%, and hyaluronidase. The MRI scans were performed before the injection and up to 35 minutes after the injection. RESULTS AND CONCLUSIONS: Reliable anesthesia is achieved using a combined peribulbar and retrobulbar block and a relatively great volume of local anesthetic solution, which spreads throughout the orbit, as evidenced by MRI. After superomedial retrobulbar and sub-Tenon's injection, the local anesthetic solution accumulates behind the globe. Sub-Tenon's injection gives good analgesia and slight akinesia with a very small volume. Superomedial retrobulbar injection and combined peribulbar and retrobulbar block provide a similar degree of exophthalmos, which seems to be the result of the volume injected behind the globe.