Vacuum-processed polyethylene as a dielectric for low operating voltage organic field effect transistors.

We report on the fabrication and performance of vacuum-processed organic field effect transistors utilizing evaporated low-density polyethylene (LD-PE) as a dielectric layer. With C60 as the organic semiconductor, we demonstrate low operating voltage transistors with field effect mobilities in excess of 4 cm2/Vs. Devices with pentacene showed a mobility of 0.16 cm2/Vs. Devices using tyrian Purple as semiconductor show low-voltage ambipolar operation with equal electron and hole mobilities of ∼0.3 cm2/Vs. These devices demonstrate low hysteresis and operational stability over at least several months. Grazing-angle infrared spectroscopy of evaporated thin films shows that the structure of the polyethylene is similar to solution-cast films. We report also on the morphological and dielectric properties of these films. Our experiments demonstrate that polyethylene is a stable dielectric supporting both hole and electron channels.

Effects of deep sedation on behaviors and side effects in children undergoing different dental procedures.

PURPOSE: The purpose of this study was to determine behavioral characteristics and side effects in children undergoing restorative dental treatment with or without dental extractions under deep sedation. METHODS: This study comprised 68 healthy 4- to 7-year-old children; 34 each were assigned to extraction and restorative groups. Children's behaviors were assessed using the following scales: (1) modified Frankl scale (preoperative period); (2) modified Houpt behavior rating scale (venipuncture period); and (3) modified Wilton behavior scale (recovery period). All complications observed during and after sedation were also recorded. RESULTS: The occurrence of agitation was higher in the extraction group; however, this difference was statistically significant only at 15 minutes after completion of sedation. In both groups, the most common side effects observed were: involuntary movement (during sedation); sleepiness; agitation and dizziness (during the early recovery period); irritability; crying; and sleepiness (following hospital discharge). CONCLUSIONS: Agitation may be observed during procedures involving extractions. Few side effects were observed during and after the sedation procedure in both groups.

Prevalence and prediction of difficult intubation in maxillofacial surgery patients.

PURPOSE: The failure to maintain a patent airway after the induction of general anesthesia is a major concern for anesthesiologists. For securing the airway, tracheal intubation using direct laryngoscopy remains the method of choice in most cases. However, direct laryngoscopic intubation is difficult in 1% to 4%, and impossible in 0.05% to 0.35%, of patients who have seemingly normal airways. This study sought to determine the prevalence of difficult intubation in maxillofacial surgery patients, and to evaluate the usefulness of various predictive tests for difficult intubation. PATIENTS AND METHODS: This study was conducted on 208 patients undergoing maxillofacial surgery. During the preoperative visit, patients were examined in terms of the test of Mallampati et al (Can Anaesth Soc J 32:429, 1985), thyromental distance, sternomental distance, and interincisal distance. Direct laryngoscopic grading, as defined by Cormack and Lehane (Anesthesia 39:1105, 1984), was recorded for each patient. An intubation of "no difficulty" was noted when the tube was inserted into the fully visualized larynx with little effort on the first attempt. RESULTS: Intubation was possible in all patients. Combinations of different predictive tests resulted in higher sensitivity. Among all test types, that of Cormack and Lahene was thought to exhibit the highest sensitivity and positive predictive values when used alone. The prevalence of difficult intubation in our group of maxillofacial surgery patients was 15.4%. It may be concluded that a combination of predictive variables can be used to improve sensitivity. CONCLUSIONS: We demonstrated that combining the Mallampati test with other instruments of measurement resulted in higher sensitivity than when either test was used alone.

Preoperative diclofenac sodium and tramadol for pain relief after bimaxillary osteotomy.

PURPOSE: The aim of this study was to compare the postoperative analgesic affects of preoperative use of a synthetic opioid tramadol and a nonsteroidal anti-inflammatory drug diclofenac sodium for postoperative pain, with placebo, in patients undergoing bimaxillary osteotomy. PATIENTS AND METHODS: Thirty-six orthognathic surgery patients who underwent both Le Fort I osteotomy in the maxilla and bilateral sagittal split ramus osteotomy in the mandible as bimaxillary osteotomy were randomly allocated into 3 groups via sealed envelope technique. Group T (n = 12), group D (n = 12), and group P (n = 12) received preoperative 50 mg tramadol intramuscularly, 75 mg diclofenac sodium intramuscularly, and saline, respectively. Postoperative pain intensity (visual analog scale, verbal pain score), postoperative opioid consumption with intravenous patient-controlled analgesia, hemodynamic variables, and postoperative complications were compared among the 3 groups. RESULTS: The median number of patient-controlled analgesia demands (n) in group P (34, 28-39) was higher than other groups (group D 14, 11-13; group T 19, 12-25; P = .001). Total tramadol consumption was higher in group P (330 mg, 290-390) compared with group D (260 mg, 190-340; P = .046) and group T (270 mg, 200-330; P = .034). The 3 groups were comparable for the area under the hemodynamic variables time curves. The area under the visual analog scale and verbal pain score curves were lower in group D and group T compared with group P, however, there was no significant difference between group T and group D. CONCLUSIONS: Preoperative diclofenac or tramadol, compared with placebo, effectively decreases postoperative opioid consumption via intravenous patient-controlled analgesia.

Effects of atracurium added to local anesthetics on akinesia in peribulbar block.

BACKGROUND AND OBJECTIVES: Peribulbar anesthesia (PBA) is widely used in cataract surgery, but the onset time of akinesia is not as rapid as with retrobulbar block. The aim of this study was to evaluate whether addition of low-dose atracurium to the local anesthetic mixture has any effects on akinesia in PBA. METHODS: Sixty adults undergoing cataract surgery were randomly allocated to receive either 8 mL of a lidocaine-bupivacaine mixture, plus 0.5 mL 0.9% NaCl (group I) or 8 mL of the same local anesthetic mixture plus 0.5 mL (5 mg) atracurium (group II). The level of akinesia was graded by a observer unaware of group assignment. The onset time and duration of akinesia were also recorded by an observer, again unaware of group assignment. RESULTS: The onset time of complete akinesia in group II was significantly shorter than that in group I (P <.05). In group I, 86% of patients had an akinesia score of 0 (complete akinesia) in the first 10 minutes. The rate of complete akinesia was 93% in group II in the same period. This difference was not significant. The success rate of complete akinesia was 93% in group I and 100% in group II at the end of the measurement interval. None of the group II patients required supplementary block, while 2 patients in group I received additional injections for inadequate akinesia. CONCLUSION: Atracurium added at a dose of 5 mg to a lidocaine-bupivacaine mixture for peribulbar block decreases the onset time of akinesia and provides better surgical conditions without obvious side-effects.

Effects of low-dose midazolam with propofol in patient-controlled sedation (PCS) for apicectomy.

We studied the effects of low-dose midazolam with propofol for patient control sedation (PCS) in 30 healthy (ASA grade I) patients who were randomly allocated into two equal groups (n = 15 in each). They were given a propofol infusion of 2mg/kg/h after a bolus dose of 0.7 mg/kg. The second group was given the 2mg/kg/h propofol infusion after a dose of midazolam 0.03 mg/kg and a bolus dose of propofol 0.7 mg/kg. The standard dose for PCS was propofol 0.2mg/kg in both groups. Clinical data were taken and haemodynamic variables, and oxygen saturation were recorded before and on the 5th, 10th, 20th, and 30th minutes during the operations. The level of sedation, amnesia and conditions of each patient were evaluated during the study. Patients' satisfaction was recorded using a modified visual analogue scale (VAS). All results were evaluated statistically. We conclude that low-dose midazolam with propofol during PCS neither reduced oxygen saturation nor prolonged the time of discharge. Low-dose midazolam with propofol also improved the acceptability and comfort for patients and made the operation easier, which makes it preferable to propofol alone.

Postoperative analgesia in orthognathic surgery patients: diclofenac sodium or paracetamol?

Our aim was to compare the analgesic affects of paracetamol and the non-steroidal anti-inflammatory drug (NSAID) diclofenac sodium for the relief of postoperative pain in patients having bimaxillary osteotomy. Thirty patients were randomly allocated into two groups (n = 15 in each) using sealed envelopes. The first group was given paracetamol 1g intravenously and the second diclofenac sodium 75 mg intramuscularly. The analgesics were given during the last 15 min of the operation while the mucosa was being sutured. The number of requests for further analgesia, and the amount of analgesia given postoperatively (as diclofenac sodium) were recorded. The intensity of postoperative pain was recorded on a visual analogue scale (VAS), and postoperative requests for analgesia, haemodynamic variables (systolic blood pressure and heart rate), and complications were compared. The groups were comparable. A single dose of diclofenac or paracetamol effectively decreases the intensity of postoperative pain after bimaxillary osteotomy.

Comparison of two different dosages of hydroxyzine for sedation in the paediatric dental patient.

AIM: This study compared the effect of two different dosages of hydroxyzine supported by 50% nitrous oxide inhalation sedation in child patients. SUBJECTS AND METHODS: Thirty uncooperative healthy children with an age range of 31-120 months were included in this study. Patients were randomly assigned into two groups. The patients in group 1 were given 20 mg of hydroxyzine (Atarax) 24 h preoperatively and on the operation day, 3.7 mg/kg hydroxyzine was administered orally. The patients in group 2 received 3.7 mg/kg hydroxyzine orally only on the operation day. All patients also received 50% nitrous oxide inhalation sedation. The child's behaviour was evaluated every 5 min by using Houpt Sedation Rating Scale. The oxygen saturation and heart rates were also followed. RESULTS: The mean age of the children in the study was 61.9 months (SD 11.9) for group 1 and 53.7 months (SD 12.8) for group 2. Evaluation of the results showed that there were no significant differences (P < 0.05) between behavioural attitudes and sedation degree of the patients. CONCLUSIONS: Twenty milligrams of hydroxyzine administered 24 h preoperatively has no significant benefit on sedation of the child.

Difficulties in anesthetic management of patients with micrognathia: report of a patient with Stickler syndrome.

Stickler syndrome is an autosomal dominant multisystem disorder with characteristic midface hypoplasia, retromicrognathia, cleft palate and a "moon-shaped" appearance. Progressive myopia and retinal degeneration are frequent. It is estimated that one third of all Pierre Robin patients have Stickler syndrome. Patients with a mandibular hypoplasia like Stickler syndrome present the anesthesiologist considerable problems when mask ventilation or endotracheal intubation is attempted. In this case report the difficulties in anesthetic management of patients with micrognathia and repeated anesthetic courses of a child with Stickler syndrome are presented. It is vital to detect the syndrome in early stages so that adequate counseling and treatment may be given to avoid the potentially irreversible and disabling consequences.

Effects of local anesthetics on pregnant uterine muscles.

Obstetric analgesia and anesthesia should provide optimal pain relief for the parturient with minimal risks. The local anesthetic agents are most commonly used for obstetric analgesia and anesthesia. We investigated the effect of local anesthetic agents: prilocaine, bupivacaine, ultracaine on myometrium in pregnant rats. In our study, we evaluated the effects of three local anesthetics at cumulative concentrations on contractions of myometrium isolated from pregnant rats. The following characteristics of the contractions were analyzed after the addition of drugs: frequency, mean duration, amplitude of each contractions and integrated area under the contraction curve. We observed that the exposure to prilocaine, bupivacaine and ultracaine decreased amplitude, duration and integrated area under the contraction curve. In conclusion, the study drugs at higher concentrations decreased contractions of myometrium, but all drugs at higher concentrations elevated the frequency.