Light emission from sources located within metallodielectric planar microcavities.

A simple, rigorous electromagnetic formula is derived for predicting the electromagnetic power provided by sources located in transparent or dissipative planar microcavities. With this simple approach, we compare numerically and experimentally the electromagnetic power that escapes the microcavity when the source is located in a metallodielectric or in an all-dielectric resonant planar structure. Although a strong light-extraction coefficient might be expected for metallodielectric microcavities, we show that these attractive structures suffer from metal absorption even when thin metallic layers are used. Experiments implemented with europium chelates located in metallodielectric or in all-dielectric microcavities confirm this result.

Thin-film luminescence under ultraviolet irradiation.

The features of visible dielectric thin-film luminescence under UV irradiation are discussed for single layers with a particular high-index/low-index couple, HfO(2)/SiO(2). We exploit those results in an attempt to understand the proper luminescence of three different mirror stacks in terms of both luminescence efficiency and angular emission.

Clonidine in pediatric caudal anesthesia.

Extradural clonidine produces analgesia in adults. To assess its efficacy in children, we randomized 45 pediatric patients aged 1-7 yr presenting for a subumbilical surgery into three groups of 15 each. After halothane and N2O/O2 induction, and with a double-blind protocol, caudal anesthesia was performed with 1 mL/kg of 0.25% bupivacaine. Epinephrine 1/200,000 was added in one group (EG), 1 microgram/kg of clonidine in another group (CG), and no additional medication in the last group (BG). Postoperative analgesia was evaluated using the Broadman "objective pain/discomfort scale" (OPS) at 1-h intervals until the first analgesic administration. There were no differences among the groups in age, weight, duration of surgery, baseline systolic arterial pressure, and heart rate. The mean (+/- SD) duration of analgesia was longer in the CG (987 +/- 573 min) than in the EG (377 +/- 341 min) and BG (460 +/- 439 min); P < 0.01. The maximal OPS scores were lower in the CG than in the EG and BG (2.3 +/- 1.6 vs 3.4 +/- 1.4 and 3.4 +/- 1.8, respectively; P < 0.05). More patients in the CG (n = 7) than in the EG (n = 1) and BG (n = 2) required no postoperative analgesia; P < 0.05. No differences were found among the groups for the minimal respiratory rate and minimal Spo2 values in the postoperative phase, and there were no differences among the groups for heart rate and systolic arterial pressure during the 3 h after caudal anesthesia. We conclude that the duration of postoperative analgesia with caudal bupivacaine was significantly increased by the addition of 1 microgram/kg of clonidine.

Intravenous nicardipine for treatment of intraoperative hypertension during abdominal surgery.

Twenty patients, American Society of Anesthesiologists class I or II, who developed intraoperative hypertension (mean arterial pressure greater than 110 mm Hg) during abdominal surgery under balanced general anesthesia were randomly assigned to two groups. The nicardipine group (n = 10) received 5 mg of nicardipine hydrochloride, and the placebo group (n = 10) received 5 mL of nicardipine solvent injected intravenously over a 5-minute period in a blind manner. Arterial pressure was recorded for 15 minutes after the injection was started. If the mean arterial pressure did not decrease at least 10% at 15 minutes, the trial was opened and patients received 5 mg of nicardipine. None of the patients in the nicardipine group received nicardipine in an open manner, in contrast with 7 of the 10 patients in the placebo group (P less than 0.03, Fisher exact test). During both the blind period and the open trial, nicardipine induced a 34% decrease in systolic, diastolic, and mean arterial pressure. Minimal values of pressure were noted at 6 minutes; however, arterial pressure remained below the pre-nicardipine injection values and near preoperative values for 45 minutes. No severe hypotension was observed, but the nicardipine injection was stopped at 3 mg in two cases during the blind period because of the rate of pressure reduction. Heart rate remained unchanged during the decrease in arterial pressure in both groups. This study indicates that nicardipine is an effective, long lasting, and safe therapy for intraoperative hypertension during abdominal surgery.

[Celiac neurolysis. Anterior approach and x-ray computed tomographic guidance: a simple and logical technic]. / Neurolyse coeliaque. Abord antérieur et guidage tomodensitométrique: une technique simple et logique.

Two cases of celiac plexus neurolysis under CT guidance by an anterior approach are reported. This technique was performed on two patients who complained of epigastric pain due to a pancreatic carcinoma. Alcoholization was performed with 50 cc of a 50% solution of ethyl alcohol. The tip of the needle was located just above the origin of the coeliac axis in front of the aorta. In the two cases the block was successful, leading to suspension of morphine administration. Computed tomography scans after injection showed that the space of diffusion corresponds to the presumed location of the celiac plexus and confirms that the anterior approach is valid providing that a sufficient dose is injected. This technique, can be easily performed and deserves a more important place in the management of pancreatic pain.