Intraocular pressure measurement with Corvis ST in comparison with applanation tonometry and Tomey non-contact tonometry.

PURPOSE: Intraocular pressure (IOP) measurement can be performed with different methods. Newer methods have to be compared to the standard method, the Goldmann applanation tonometry (GAT). We herein compare two air-puff tonometers, the non-contact tonometer (Tomey NCT) and the Corvis ST (CST) with GAT in eyes with a broad spectrum of IOP. METHODS: Two hundred and forty-nine eyes of 249 patients (with diagnosis of either glaucoma or ocular hypertension) were included in this monocenter prospective cohort study. Each eye underwent IOP measurements via GAT, NCT and CST. Bland-Altman plots were calculated to compare the different methods in the three groups. Paired t tests were used for statistical comparison between the three measurement methods. The difference between the different methods was tested on correlation against central corneal thickness (CCT). RESULTS: Mean IOP in GAT was 17.6 mmHg (standard deviation (SD) 5.9), 16.3 mmHg (SD 5.6) in NCT and 18.0 mmHg (SD 5.5) in CST. Comparisons between GAT and CST vs. NCT showed significant differences (p < 0.001), while GAT vs. CST showed no significant difference (p = 0.1162). Mean CCT was 538.7 µm (SD 35.1). CONCLUSIONS: Mean values of GAT and CST show comparable results. However, both GAT and CST differ significantly from NCT. NCT shows lower IOP values compared to both other methods.

Bleb-related infections and long-term follow-up after trabeculectomy.

PURPOSE: Bleb-related infections are serious complications after trabeculectomy. They can be limited to the bleb or disseminate and lead to endophthalmitis. We herein report on all bleb-related infections that have been diagnosed at the Eye Center of the University of Freiburg, Germany, since 1999. METHODS: We reviewed a total of 1816 consecutive trabeculectomies that were performed at our hospital between the years 1999 and 2014 (353 without and 1463 with intraoperative application of mitomycin C). All bleb-related infections that were diagnosed at our clinic during the same period were included in the analysis. We fitted a Cox proportional hazards model to characterize risk factors for bleb-related infections. RESULTS: We diagnosed a total of 19 bleb-related infections in this period. Three patients with bleb-related infections that came to our clinic had their trabeculectomy performed elsewhere. The overall percentage of bleb-related infections was 0.1% after 2 years (Kaplan-Meier estimate at median follow-up). Nine eyes suffered from only localized infection of the bleb. Seven eyes developed endophthalmitis. Four infections occurred during the first postoperative month. The median age on the day of diagnosis was 71 years; the median age at surgery was 69 years. In the Cox model, intraoperative application of mitomycin C and a fornix-based conjunctival flap were identified as significant risk factors (hazard ratio: 79.02, 4.69; p < 0.01, p < 0.01). The whole group showed a reduction of visual acuity in the median from logMAR 0.12 to 0.2. Eyes that suffered from endophthalmitis showed a loss from 0.3 to 0.96, while the localized infections had a reduction from 0.04 to 0.07. CONCLUSION: Bleb-related infections are a rare complication following trabeculectomy and can be localized on the bleb or can lead to endophthalmitis, thereby threatening visual acuity. The risks and benefits of mitomycin C-augmented trabeculectomies should be taken into consideration.

Refractive and visual outcomes after combined cataract and trabectome surgery: a report on the possible influences of combining cataract and trabectome surgery on refractive and visual outcomes.

PURPOSE: To compare combined trabectome-cataract surgery with cataract-alone surgery regarding their refractive and visual outcomes and complications. METHODS: In 137 eyes that underwent combined trabectome-cataract surgery, the postoperative refraction error and best visual acuity after at least 2 months postoperatively were compared to those of an in-house control group of 1,704 eyes that underwent outpatient cataract surgery. RESULTS: Combined trabectome-cataract surgery showed no significant differences regarding the biometry prediction error (BPE, mean 0.53 D vs. 0.48 D, p = 0.24) or visual outcome (BCVA, 0.81 vs. 0.78, p = 0.06). The rate of postoperative cystoid macular edema was slightly higher in the combined surgery group (2.2 % vs. 1.9 %). CONCLUSIONS: Refractive and visual outcomes were similar in both groups. Despite the slightly higher rate of postoperative macula edema, we were able to observe that the combination of these two procedures is a feasible method in glaucoma and cataract surgeries.

[Localization of peripheral nerves. Success and safety with electrical nerve stimulation]. / Lokalisation peripherer Nerven. Erfolg und Sicherheit mit elektrischer Nervenstimulation.

Peripheral electrical nerve stimulation is one of the standard applications in peripheral regional anesthesia in addition to the ultrasound technique. Among other findings, the visualization of needle and nerve during ultrasound-guided blockade caused a change in clinical practice of peripheral nerve stimulation in the last decade. In the present article old and new aspects of principles and clinical practice of the nerve stimulation technique are presented and summarized in a total clinical concept in order to achieve safe and successful peripheral regional anesthesia using electrical peripheral nerve stimulation.

Nerve localization for peripheral regional anesthesia. Recommendations of the German Society of Anaesthesiology and Intensive Care Medicine.

The German Society of Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin, DGAI) established an expert panel to develop preliminary recommendations for nerve localization in peripheral regional anesthesia. Based on expert knowledge and the relatively limited data, the recommendations state how ultrasound and/or electrical nerve stimulation should be used in daily practice, and where and when local anesthetics should be injected. Moreover, it was defined under which conditions a peripheral nerve block under general anesthesia or deep sedation is applicable.Regarding the use of ultrasound the expert opinion was that out-of-plane and in-plane-techniques can be considered equal with respect to patient safety. Nevertheless, the direct or indirect visualization of the needle tip has to be assured. The injection of local anesthetics has to be visualized. Injections into nerves or those requiring an injection pressure should be avoided. The sole use of electrical nerve stimulation or ultrasound for nerve localization is still a suitable option as well as their combined use. To avoid accidental intraneural needle placement, an electrical current threshold ≥ 0.5 mA should be used. Moreover, it was stated that peripheral nerve blocks or continuous nerve block techniques under sedation or general anesthesia are applicable in adult patients who are unable to tolerate the block being performed in an awake state or have difficulty cooperating.This article is published in English.

[Body mass index as an influencing factor for outcome of trabectome surgery?]. / Einfluss des Body-Mass-Index auf den Erfolg nach Trabektomoperation?

BACKGROUND: The aim of this study was to investigate a possible influence of body mass index (BMI) to the outcome of trabectome surgery. METHODS: 131 eyes with primary open angle glaucoma, myopia-associated glaucoma and pseudoexfoliation glaucoma were included into this retrospective study. The data were extracted from the Freiburg trabectome database from June 2009 to April 2013. We fitted a Cox proportional hazards model in order to assess the influence of the BMI on trabectome outcome. RESULTS: The absolute success after trabectome surgery (20 % pressure reduction without anti-glaucomatous medication) was statistically significantly better in the group with BMI > 25 kg/m(2) (p = 0.047). No statistically significant effect was observed for relative success or the rate of re-operation respectively. CONCLUSION: In our patient cohort of 131 eyes, a high BMI was associated with a reduced success, as long as an absolute success is required. No difference is seen if additional anti-glaucomatous medication is acceptable (relative success).

[Successful infection control in regional anesthesia procedures: observational survey after introduction of the DGAI hygiene recommendations]. / Erfolgreiche Infektionskontrolle bei Regionalanästhesieverfahren: Verlaufsbeobachtung nach Einführung der DGAI-Hygieneempfehlungen.

BACKGROUND: In the context of regional anesthesia procedures adverse events rarely occur but are predominantly systemic intoxication due to local anesthetics (0.01-0.035 %), nerve injuries (0.01-1.7 %) and infections (0-3.2 %). MATERIALS AND METHODS: In a level 1 trauma centre data from all continuous peripheral nerve blocks (cPNB) were prospectively acquired over a period of 8 years (2002-2009) in an observational study (n = 10,549). The acquisition of data was carried out in an intranet-based data bank which was accessible for 24 h on every anesthesia workstation. The collected data included type of block, catheter duration and accompanying complications. This study was carried out with special respect to infectious complications (inflammation and infection). RESULTS: In the years 2002-2004 unexpectedly high rates of infectious complications were observed in 3,491 cPNBs with 146 inflammations (4.2 %) and 112 infections (3.2 %). Based on these alarming findings the existing hygiene regime was revised. The innovations were incorporated into the "Hygiene recommendations for the initiation and continued care of regional anaesthetic procedures" of the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin, DGAI). A major change was the extension of skin disinfection to a spray-and-scrub combined procedure lasting 10 min. The introduction of this care bundle was carried out in 2005. Among 7,053 cPNBs that were conducted between 2005 and 2009 inflammation occurred in only 183 procedures (2.6 %) and infection in 61 procedures (0.9 %). This reduction was highly significant in both categories (p < 0.001). The risk factors catheter duration and catheter localization statistically remained unchanged during the observational period CONCLUSION: Using a real-time computer-based tool for data capture makes a veritable detection of adverse events possible. Such a tool also has the power to monitor the effects of changes in clinical procedures (SOP). In this case it was possible to verify the successful introduction of an extended hygiene care bundle. The new regime significantly decreased the rate of infections in cPNB.

[Complications of peripheral regional anesthesia]. / Komplikationen bei peripherer Regionalanästhesie.

Peripheral regional anesthesia is a commonly used and safe procedure and eneral complications or side effects are generally rare. Nerve damage has an incidence <0.1% depending on the definition and the prognosis is good. To avoid bleeding complications the national standards of block performance under antithrombotic therapy should be respected. Intoxication is mainly the result of accidental intravenous administration and is difficult to treat but higher doses of intravenous lipid emulsions can improve the outcome. Potential infectious complications can occur mainly as a result of catheter techniques and require a strict aseptic approach. Further rare complications are allergies, dislocation of catheters and knotting or loops in catheters. Besides the general complications, there are some specific complications depending on the puncture site, such as pneumothorax or renal puncture.

[Perivascular brachial plexus block. Ultrasound versus nerve stimulator]. / Perivaskuläre axilläre Plexusanästhesie. Ultraschall versus Nervenstimulator.

BACKGROUND: Optimizing the needle position using ultrasound (US) instead of electrical nerve stimulation (NSt) is increasingly common for perivascular brachial plexus block. These two methods were compared in a prospective, randomized, single-blinded controlled trial regarding effectiveness and time of onset of peripheral nerve blockade. METHODS: After puncture (penetration of neurovascular sheath and complete insertion of needle) 56 patients were randomly assigned to either the US group (finding the needle tip in transpectoral section, short axis, correction of needle position if local anesthetic spread was insufficient) or the NSt group (target impulse reaction in median, ulnar or radial nerve of 0.3 mA/0.1 ms, if necessary correction of position before injection of local anesthetic) to verify the needle position. All patients received 500 mg 1% mepivacaine. Sensory and motor blocks were tested by single nerve measurements (SNM) 5, 10 and 20 min after finishing the injection, where 0 represents minimal and 2 maximal success of the block. RESULTS: Single nerve measurements were analyzed using repeated measures ANOVA. The mean results of cumulative SNMs were significantly higher in the US group at all measurement times. Sensitivity US/NSt: 5 min: 3.36±2.32/2.63±1.87; 10 min: 5.45±2.41/4.21±2.45; 20 min: 7.30±2.02/6.43±2.43, p=0.015, motor function US/NSt: 5 min: 3.91±1.81/3.02±1.67; 10 min: 5.27±1.66/4.05±1.70; 20 min: 6.64±1.37/5.50±1.90, p<0.001. At the beginning of surgery complete nerve blockade was achieved in 89% in the US group and 68% in the NSt group (p=0.006), 3 (US) versus 7 (NSt) patients needed supplementation and 3 (US) versus 11 (NSt) patients needed general anesthesia (p=0.022). To achieve the nerve block took approximately 1 min more in the US group (p=0.003). CONCLUSION: The use of ultrasound in perivascular brachial plexus blocks leads to significantly higher success rates and shorter times of onset.

[Techniques of intraocular pressure measurement]. / Messverfahren der Tonometrie.

The correct interpretation of measured tonometric values has become more and more complex in recent years. Large clinical studies have shown that an average central corneal thickness (CCT) of 550 µm can be assumed for the general population. Since the standard Glodmann applanation tonometry is based on a central corneal thickness of 520 µm, mathematical correction formula have been discussed for calculation of the true intraocular pressure. Newer tonometry devices, e. g. the dynamic contour tonometry (DCT) which seems to be independent from CCT, or the Ocular Response Analyzer® (ORA), taking into account the biomechanical properties of the cornea, have been designed to measure intraocular pressure (IOP). In this article, several IOP measurement devices and their clinical relevance for a correct and feasible determination of the IOP are discussed.

[Factors influencing applanation tonometry - a practical approach]. / Einflussgrößen auf die Applanationstonometrie - ein praxisorientierter Überblick.

Applanation tonometry has been the gold standard in clinical ophthalmology for more than fifty years. The most popular factor is central corneal thickness that is now routinely considered in glaucoma management. However, other individual features of the cornea can also play a key role for the interpretation of the applanation values. Other factors influencing applanation tonometry that have been well known for decades include tear film, fluorescein illumination etc., and should be kept in mind. According to the available literature the absence of a correct calibration cannot be neglected.

[Infection control in continuous peripheral regional anesthesia. Clinical study on disinfection time and subcutaneous tunneling in interscalene plexus anesthesia]. / Infektionsreduktion bei peripherer Katheterregionalanästhesie: Klinische Studie zur Desinfektionszeit und zur subkutanen Tunnelung bei interskalenärer Plexusanästhesie.

In the present study the efficacy of subcutaneous tunneling and a 10 min disinfection time with a 70% alcoholic solution to reduce the infection rate in continuous interscalene plexus anesthesia were examined. In a prospective study 1,134 continuous interscalene plexus anesthesias were included. In group 1 (473 catheters) a cotton swab was soaked with the alcoholic solution and swabbed 3 times at the puncture site in the classical manner. In group 2 (661 catheters) disinfection was carried out by spray and swab application with a disinfection time of at least 10 min. In group 1, 19% of the catheters were tunneled subcutaneously, whereas in group 2 this occurred in 89%. In group 1 inflammation occurred in 25 cases (5.3%) and an infection in 32 cases (6.8%). In group 2 there were 37 cases of inflammation (5.5%) and 13 infections (2.0%). The difference between the groups in the infection rate is statistically significant (p<0.002). The practicability of the 10 min disinfection time in the clinical routine was excellent. A 10 min disinfection time with a 70% alcoholic solution combined with subcutaneous tunneling led to a significantly lower infection rate in continuous peripheral regional anesthesia in the neck of the patient.

[Alterations in intraocular pressure and the CorVis parameters after LASIK]. / Änderung des Augeninnendrucks und der CorVis-Parameter nach LASIK.

INTRODUCTION: The reduction of corneal thickness following laser-assisted in-situ keratomileusis (LASIK) requires a correction of intraocular pressure (IOP) measurements. The corneal visualization Scheimpflug technology (CorVis ST, Oculus, Wetzlar, Germany) not only measures the IOP and central corneal thickness (CCT) but also determines 10 additional corneal parameters, such as the time to first and second applanation and velocity. Besides CCT we compared various corneal parameters before and after LASIK in order to detect possible correlations and to correct IOP measurements. METHODS: Measurements with CorVis ST were made before and after LASIK in 45 myopic patients (45 left eyes). We compared the IOP and CorVis ST parameters using a paired t­test before and after LASIK and corrected for possible correlations in a multifactorial linear model. Finally, we correlated the changes in IOP to changes in biomechanical parameters. RESULTS: We observed a direct correlation between the IOP measurements and the corneal thickness. The IOP was underestimated by 0.039 mm Hg per micrometer in reduction of corneal thickness. The multifactorial linear model showed a correlation of IOP change to A2 velocity and the radius of applanation. CONCLUSION: Surgical thinning of the central cornea via LASIK demonstrated a direct correlation between corneal thickness and IOP measurements using the CorVis ST technique. Postoperative changes of the A2 velocity and the applanation radius also had a statistically significant influence on post-LASIK IOP measurements. Our findings could be useful to obtain more precise post-LASIK IOP measurements.

Biochemical dissection of photorespiration.

Progress has been made in the understanding of photorespiration and related proteins (Rubisco, glycolate oxidase and glycine decarboxylase) in the context of recent structural information. Numerous shuttles exist to support transamination, ammonia refixation and the supply or export of reductants generated or consumed (via malate-oxaloacetate shuttles) in the photorespiratory pathway. A porin-like channel that is anion selective represents the major permeability pathway of the peroxisomal membrane.

The glycine decarboxylase system: a fascinating complex.

The mitochondrial glycine decarboxylase multienzyme system, connected to serine hydroxymethyltransferase through a soluble pool of tetrahydrofolate, consists of four different component enzymes, the P-, H-, T- and L-proteins. In a multi-step reaction, it catalyses the rapid destruction of glycine molecules flooding out of the peroxisomes during the course of photorespiration. In green leaves, this multienzyme system is present at tremendously high concentrations within the mitochondrial matrix. The structure, mechanism and biogenesis of glycine decarboxylase are discussed. In the catalytic cycle of glycine decarboxylase, emphasis is given to the lipoate-dependent H-protein that plays a pivotal role, acting as a mobile substrate that commutes successively between the other three proteins. Plant mitochondria possess all the necessary enzymatic equipment for de novo synthesis of tetrahydrofolate and lipoic acid, serving as cofactors for glycine decarboxylase and serine hydroxymethyltransferase functioning.

Effect of bicarbonate and oxaloacetate on malate oxidation by spinach leaf mitochondria.

Mitochondria isolated from spinach leaves oxidized malate by both a NAD+-linked malic enzyme and malate dehydrogenase. In the presence of sodium arsenite the accumuation of oxaloacetate and pyruvate during malate oxidation was strongly dependent on the malate concentration, the pH in the reaction medium and the metabolic state condition. Bicarbonate, especially at alkaline pH, inhibited the decarboxylation of malate by the NAD+-linked malic enzyme in vitro and in vivo. Analysis of the reaction products showed that with 15 mM bicarbonate, spinach leaf mitochondria excreted almost exclusively oxaloacetate. The inhibition by oxaloacetate of malate oxidation by spinach leaf mitochondria was strongly dependent on malate concentration, the pH in the reaction medium and on the metabolic state condition. The data were interpreted as indicating that: (a) the concentration of oxaloacetate on both sides of the inner mitochondrial membrane governed the efflux and influx of oxaloacetate; (b) the NAD+/NADH ratio played an important role in regulating malate oxidation in plant mitochondria; (c) both enzymes (malate dehydrogenase and NAD+-linked malic enzyme) were competing at the level of the pyridine nucleotide pool, and (d) the NAD+-linked malic enzyme provided NADH for the reversal of the reaction catalyzed by the malate dehydrogenase.

Crystallographic data for H-protein from the glycine decarboxylase complex.

The H-protein is the pivotal enzyme of the glycine decarboxylase complex responsible for the oxidation of glycine by mitochondria. It has been extracted and purified from pea leaf mitochondria (Pisum sativum). Its molecular weight, based on the amino acid sequence, is 13.3 kDa and it crystallizes in the space group P3(1)21 (or its enantiomorph P3(2)21) with a = b = 57.14 (3) A, c = 137.11 (11) A. The crystals diffract until at least 3.5 A resolution.

Effect of High Physiological Temperatures on NAD+ Content of Green Leaf Mitochondria (Apparent Inhibition of Glycine Oxidation).

We observed a rapid decline in the rate of glycine oxidation by purified pea (Pisum sativum L.) leaf mitochondria preincubated at 40[deg]C for 2 min. In contrast, exogenous NADH and succinate oxidations were not affected by the heat treatment. We first demonstrated that the inhibition of glycine oxidation was not attributable to a direct effect of high temperatures on glycine decarboxylase/serine hydroxymethyltransferase. We observed that (a) addition of NAD+ to the incubation medium resulted in a resumption of glycine-dependent O2 uptake by intact mitochondria, (b) addition of NAD+ to the suspending medium prevented the decline in the rate of glycine-dependent O2 consumption by pea leaf mitochondria incubated at 40[deg]C, (c) NAD+ concentration in the matrix space collapses within only 5 min of warm temperature treatment, and (d) mitochondria treated with the NAD+ analog N-4-azido-2-nitrophenyl-4-aminobutyryl-3[prime]-NAD+ retained high rates of glycine-dependent O2 uptake after preincubation at 40[deg]C. Therefore, we conclude that the massive and rapid efflux of NAD+, leading to the apparent inhibition of glycine oxidation, occurs through the specific NAD+ carrier present in the inner membrane of plant mitochondria. Finally, our data provide further evidence that NAD+ is not firmly bound to the inner membrane.

DNA content, ploidy level and number of nuclei in the human heart after myocardial infarction.

OBJECTIVE: Cardiac hypertrophy due to a prolonged functional activity is associated with an increase of cell size and polyploidization of the myocyte nuclei. Myocardial infarction is characterized by loss of myocytes. Increased load and as a consequence hypertrophic growth of the surviving myocardium has to be expected. The aim of this study was to investigate the response of cardiomyocytes after infarction. METHOD: Biochemical and cytophotometric analysis was performed on myocyte and connective tissue nuclei to determine whether the human heart after myocardial infarction is accompanied by an increase in the ploidy level, DNA content and in the number of nuclei. A total of 15 hearts obtained from autopsy material was studied, among them 8 after myocardial infarction. The number of nuclei was measured by indirect computation. RESULTS: We found a decrease of 4c and no significant difference of 2c nuclei in infarcted hearts. DNA ploidy level (> 8c) as well as the proportion of aneuploid myocyte nuclei were increased in infarcted hearts. DNA concentration and total DNA content were increased in the hearts after myocardial infarction. Numerical ratio of connective tissue nuclei/myocyte nuclei, total number of nuclei, number of myocyte nuclei and number of connective tissue nuclei were increased in infarcted hearts. CONCLUSION: Polyploidization and nuclear hyperplasia of myocytes may represent an adaptive response of the myocardium to an ischemic injury.