[Minimal-invasive Cochlear Implantation: Surgical feasibility and first clinical experience]. / Die minimal-invasive Cochlea-Implantation ­ Chirurgische Machbarkeit und erste klinische Erfahrungen.

OBJECTIVE: Cochlear implantation is a standard procedure for rehabilitation of profound hearing loss and single sided deafness. Audiologic criteria for implantation have been extended with the growing experience. Less traumatic access has been developed at the same time. METHODS AND PATIENTS: This study reports first experiences with a minimaltraumatic cochlear implantation (MiCI) approach in a series of 31 consecutive patients (9-79 yrs.) in our department. The approach combines a short retroauricular incision of 25mm with a minimized mastoidectomy, a round window approach and a temporal well for the implant. RESULTS: Retroauricular incision could be reduced to 29, 7 mm, the size of the mastoid cavity to 20 mm2 and the stay in hospital for 0,55 days in average. Main postoperative complaint was dizziness. Overall complication rate was comparable to conventional surgery. CONCLUSION: Minimal-invasive cochlear implantation is a safe and reliable procedure in experienced hands for children and adults.

A rare but serious complication of GreenLight HPS photoselective vaporization of the prostate: Prostatic capsular perforation with bilateral thigh urinomas and osteitis pubis.

The use of lasers to perform photoselective vaporization of the prostate (PVP) has been widely accepted as a safe and effective treatment for benign prostatic hyperplasia with very few reported complications. To date, most of the published data report outcomes for the 80-W potassium-titanyl-phosphate laser. A more potent laser, the 120-W GreenLight HPS, was introduced in 2006 and provides more efficient vaporization of prostatic tissue and decreased operating times. Despite these benefits, the increased energy applied to the prostate evokes concerns of potential serious complications, including capsular perforation and injury to adjacent structures. A more powerful laser system, the 180-W GreenLight XPS laser (American Medical Systems, Minnetonka, MN) has recently become available. We report a rare but serious complication of GreenLight HPS PVP resulting in prostatic capsular perforation with urinary extravasation, presenting with bilateral thigh urinomas and osteitis pubis.

Sonotubometry with perfect sequences: First results in pathological ears.

CONCLUSION: Sonotubometry with perfect sequences (PSEQ) was able to detect eustachian tube (ET) openings in both normal and pathological ears. Impaired ears showed ET openings in almost all cases; however, these proved to be not only less frequent, but also with lower amplitude and shorter duration. OBJECTIVES: To investigate the function of impaired ET under physiological conditions, using a novel kind of sound stimulus for sonotubometry ­ the PSEQ. METHODS: Twenty otologically healthy subjects (40 normal ears) and 32 patients with ear diseases (40 pathological ears) were examined sonotubometrically using noise signals with an ideally flat spectrum (PSEQ). Dry swallowing, water swallowing, and Toynbee maneuver were used to induce ET openings. Analysis was performed regarding the frequency of occurrence, duration, amplitude, and form of the ET openings. RESULTS: PSEQ allowed the detection of an ET opening in all 40 normal ears (91% of the performed maneuvers) and in 87.5% of the ears with impaired ET function (but only 47% of the maneuvers). The average amplitude of the openings in healthy ears was 16.86 dB, the average duration was 363 ms. In diseased ears these values were significantly lower: 9.73 dB, p < 0.001 and 280 ms, p < 0.05.

Evaluation of Eustachian tube function with perfect sequences: technical realization and first clinical results.

The aim of this study was the introduction of a specific class of signals, the so-called perfect sequences (PSEQ), in a novel approach for sonotubometry of the Eustachian tube (ET). Sonotubometry using PSEQ stimuli was performed on 20 healthy subjects in order to gauge its potential for clinical applications. In a series of 320 measurements ET opening was probed, which was induced by dry and water swallowing, Toynbee maneuver, and yawning. All sonotubograms were analyzed with respect to their shape, increase of sound intensity, and opening duration. In 298/320 measurements (>93%) the subjects reported subjective ET openings. The evaluation of the recorded sonotubograms showed good detection of ET opening for the inducing maneuvers of swallowing (dry and water swallowing) and the Toynbee maneuver, with 90, 86, and 80% valid sonotubograms, respectively. Yawning led to only 40% valid sonotubograms. In total, 237/320 (~74%) sonotubograms were classified as valid. The evaluation of the sound level increase during ET openings showed that it was significantly higher in measurements with dry and water swallowing, as well as Toynbee maneuvers (mean 17.1, 19.0 and 17.2 dB, respectively), than with yawning (mean 10.17 dB; P < 0.0001). Nasal decongestion was found to have little influence on the results (P > 0.05). Sonotubometry using PSEQ stimuli is a novel sonotubometry methodology that provides valuable information regarding the auditory tube patency. By further technical refinements of the method, a diagnostic tool with high sensitivity and specificity could be developed.

Evaluation of Eustachian tube function by sonotubometry: results and reliability of 8 kHz signals in normal subjects.

Sonotubometry allows an assessment of the Eustachian tube (ET) function under physiological conditions. The reliability of the application of an 8 kHz pure-tone signal was investigated. In 40 normal subjects (80 ears) sonotubometric studies were performed with a custom-made device. ET opening was provoked by swallowing, yawning and Valsalva manoeuvre. An opening was detected in all patients but not in all manoeuvres. Four characteristic sonotubogram types were found. Most common was the spike-type (60%). The double-peak and the plateau-shaped curves occurred in 17% each. The finding of an descendant curve was rare (5%). Of 623 measurements, only in 55% manouvres a positive sonotubometric result was found despite the fact that the patients reported an opening in all cases. The median opening time in dry swallowing, liquid swallowing, yawning and Valsalva was found to be 486, 355, 1,263 and 1,250 ms. A median sound increase of 16.0, 13.8, 15.0 and 15.0 dB was recorded for these manoeuvres. There was a statistic significant difference (P < 0.02) between the increase in sound intensity of liquid and dry swallowing. There was also a statistic significant difference found for the duration of the forced manoeuvres Valsalva and yawning as compared to dry and liquid swallowing (P < 0.0001). The use of an 8 kHz pure-tone signal showed a limited sensitivity for the detection of ET openings. This is mainly due to noise pollution, but also because of an altered positioning and/or dislocation of the probes and compression of the nostrils. The application of an 8 kHz signal is therefore not reliable enough for the use in practice. Further technical refinements and the use of alternative signals are necessary for a broader clinical application.

Evaluation of tumor oxygenation by color duplex sonography: a new approach.

OBJECTIVE: Description of a new noninvasive method for the evaluation of tissue oxygenation in head and neck cancer. STUDY DESIGN AND SETTING: Prospective nonrandomized controlled study in an academic medical center on 20 patients with neck metastases of head and neck cancer. Metastases were investigated using color duplex sonography and pO2 histography. The vascularization in sonography was quantitatively evaluated by color pixel density and compared to the pO2 values of the same nodes. RESULTS: The correlation between vascularization and flow velocity was 0.71. For the mean/median pO2 -values and for the pO2 readings <10.0 mmHg correlations were r = 0.65 / 0.76 and 0.71. CONCLUSION: This sonographic method allows a safe and reliable evaluation of oxygenation in metastases of head and neck cancer. SIGNIFICANCE: The new approach is an alternative to pO2 histography and may play a future role in the planning of radiotherapy in the neck.

Variability in determination of point of needle insertion in peripheral nerve blocks: a comparison of experienced and inexperienced anaesthetists.

Accurate identification of surface landmarks is essential for the successful performance of peripheral nerve blocks. The variability between experienced and inexperienced practitioners in identifying anatomical landmarks has not been studied previously. Anaesthetists were asked to identify the point of needle insertion for posterior lumbar plexus and sciatic nerve blocks on a volunteer using a standard textbook description. The chosen point for needle insertion was described in terms of X and Y co-ordinates, measured in millimetres, from a zero reference point marked on a volunteer's back. Fifteen experienced and 22 inexperienced anaesthetists took part in the study. The lumbar plexus block mean [range] values for the X, Y co-ordinates were 80 [62-108], 66 [46-86] and 92 [49-150], 62 [0-131] in the experienced and inexperienced groups, respectively. The sciatic nerve block X, Y co-ordinates were 77 [62-99], 70 [49-89] and 68 [29-116], 62 [26-93] in the experienced and inexperienced groups, respectively. The variance for the point of needle insertion was significantly greater in the inexperienced group (p <0.01) for both the lumbar plexus and sciatic nerve blocks. We conclude that with increasing experience, there is decreased variability in determining the point of needle insertion using anatomical landmarks.

Improving the performance of an acid-labile 4-hydroxymethyl phenoxyacetic acid (HMP) linker on resin and SynPhase grafted solid-supports.

A replacement of the acetic acid moiety by valeric acid within the 4-hydroxymethylphenoxyacetic acid (HMP) linker (Sheppard RC, Williams BJ. Acid-labile resin linkage agents for use in solid phase peptide synthesis. Int. J. Peptide Protein Res. 1982; 20: 451-454) significantly improved its performance in terms of loading capacity, yield and purity of the final products. The results indicated the spacer-linker combination and type of solid supports are important factors for solid-phase synthesis.

Grafted supports in solid-phase synthesis.

Solid-phase synthesis is greatly dependent on the solid phase. We are interested in the development of a "pellicular" type of solid support where a more mobile polymer is grafted to rigid plastics. Compared to low cross-linked microporous beads that dominate the field, this approach allows great flexibility of design, as plastics are available as sheets, films, or threads, or can be molded into any shape, as required. Many different polymers or copolymers can be grafted onto any particular shape to give a wide choice of options in the physicochemical characteristics of the actual solid support. As an example of such a solid support, we report on polystyrene-grafted polypropylene in a particular shape that we have called "Lanterns." Its synthesis characteristics are compared to the commonly available low cross-linked polystyrene resins. As well, the handling advantages of these types of supports in multiple synthesis are highlighted.

Thromboelastography as a perioperative measure of anticoagulation resulting from low molecular weight heparin: a comparison with anti-Xa concentrations.

UNLABELLED: Low molecular weight heparin (LMWH) is commonly used to prevent postoperative thromboembolism. Currently, there is no convenient test to measure the degree of anticoagulation from LMWH. This prospective study examines the relationship of thromboelastography and serum anti-Xa concentration in patients treated with enoxaparin. Twenty-four adult patients scheduled for orthopedic surgery using epidural anesthesia were enrolled. Epidural catheters were removed the morning after surgery before the commencement of subcutaneous enoxaparin 30 mg twice daily. Venous blood samples were obtained at 1) the induction of anesthesia (baseline), 2) immediately before the third dose of enoxaparin postoperatively (Day 2-trough), 3) 4 h after the third dose postoperatively (Day 2-peak), and 4) immediately before the fifth dose postoperatively (Day 3-trough). Whole blood samples were obtained for thromboelastography, activated clotting time, and anti-Xa level analyses at each of the four time intervals. At the four sample intervals, the r time (mean +/- SEM). (20 +/- 1, 25 +/- 2, 51 +/- 6, 31 +/- 3 mm) and the k time (9 +/- 0. 7, 12 +/- 1, 27 +/- 5, 14 +/- 2 mm) of the thromboelastograph were significantly correlated with the expected peak and trough levels of LMWH and serum anti-Xa levels (P: < 0.05). At the Day 3-trough, thromboelastograph r times exceeded the normal range in 6 of 25 patients (25%). Prolongation of r time and k time on postoperative Day 3 may indicate an exaggerated response to LMWH. Thromboelastography is a test that could potentially correlate with the degree of anticoagulation produced by low molecular weight heparin. IMPLICATIONS: Thromboelastography is a test that could potentially correlate with the degree of anticoagulation produced by low molecular weight heparin. The r time from the thromboelastogram correlates with serum anti-Xa concentration.

Solid phase synthesis of C-terminal peptide amides: development of a new aminoethyl-polystyrene linker on the Multipin solid support.

A new aminoethyl-polystyrene linker, stable at low concentrations of TFA, has been developed for the solid phase synthesis of peptide amides. The described linker is stable under conditions which remove Bu(t) protecting groups (30-50% TFA in DCM) and the desired product can be finally cleaved off the solid support in 95% TFA (5% H2O). Model peptide amides and other N-alkylated peptide amides have been successfully synthesized in good yield and purity.

Acetophenone-based linker for solid-phase peptide synthesis.

A new and cost-effective linker for the generation of carboxylic acid end groups on Multipin supports (SynPhase crowns) has been developed. Synthesis of the linker was based on modification of grafted polystyrene (PS) crowns to generate a hydroxyethyl moiety which is acid labile in 10-20% trifluoroacetic acid (TFA) in dichloromethane (DCM). Solid-phase syntheses of model decapeptides using this linker are described.

Spinal cord neural anatomy in rats examined by in vivo magnetic resonance microscopy.

BACKGROUND AND OBJECTIVES: Magnetic resonance microscopy (MRM) is a technique that is worthwhile for anesthesiologists because it allows spinal cord and plexus anatomy to be visualized three dimensionally and followed over time in the same animal. For example, the long-term effect of indwelling intrathecal or plexus catheters can be studied in situ, and convective and diffusive forces within intrathecal, epidural, or nerve sheath spaces can be investigated. Further, diffusion-weighted MRM, which measures an "apparent diffusion coefficient" (ADC), can be used to track the presence of ischemia, hypoperfusion, or cytotoxic edema. This study investigates problems associated with the use of in vivo MRM for spinal cord and peripheral nerve studies in the rat. METHODS: Twenty-one anesthetized female Fisher CDF rats were used. Group 1 (n=7) was used for anatomic three-dimensional studies. Groups 2 (n=4), 3 (n=4), and 4 (n=6) were used for measurements of the ADC. Group 2 served as controls, group 3 received lumbar intrathecal catheters, and group 4 received cervical intrathecal catheters. RESULTS: Cervical spine, lumbar spine, and spinal nerves and ganglia were accurately visualized with MRM. As a rule, spinal cord gray and white matter were better demonstrated using diffusion-weighted proton stains. By contrast, T2-weighted proton staining superiorly demonstrated structures surrounding the spinal cord. In groups 3 and 4, indwelling intrathecal catheters did not affect the spinal cord ADC, indicating normal blood flow and no cytotoxic edema. Contrast studies revealed nonhomogeneous distribution of contrast predominately in the lateral and ventral intrathecal space. CONCLUSION: Three-dimensional diffusion-weighted MRM displays cervical and lumbar spine anatomy accurately in vivo. Apparent diffusion coefficients measurements are feasible in rat cervical spinal cord with intrathecal catheters. Spinal cord ADCs are unaffected by intrathecal catheters, indicating normal spinal cord perfusion.

A comparison of 0.5% bupivacaine, 0.5% ropivacaine, and 0.75% ropivacaine for interscalene brachial plexus block.

UNLABELLED: The onset time and duration of action of ropivacaine during an interscalene block are not known. The potentially improved safety profile of ropivacaine may allow the use of higher concentrations to try and speed onset time. We compared bupivacaine and ropivacaine to determine the optimal long-acting local anesthetic and concentration for interscalene brachial plexus block. Seventy-five adult patients scheduled for outpatient shoulder surgery under interscalene block were entered into this double-blind, randomized study. Patients were assigned (n = 25 per group) to receive an interscalene block using 30 mL of 0.5% bupivacaine, 0.5% ropivacaine, or 0.75% ropivacaine. All solutions contained fresh epinephrine in a 1:400,000 concentration. At 1-min intervals after local anesthetic injection, patients were assessed to determine loss of shoulder abduction and loss of pinprick in the C5-6 dermatomes. Before discharge, patients were asked to document the time of first oral narcotic use, when incisional discomfort began, and when full sensation returned to the shoulder. The mean onset time of both motor and sensory blockade was <6 min in all groups. Duration of sensory blockade was similar in all groups as defined by the three recovery measures. We conclude that there is no clinically important difference in times to onset and recovery of interscalene block for bupivacaine 0.5%, ropivacaine 0.5%, and ropivacaine 0.75% when injected in equal volumes. IMPLICATIONS: In this study, we demonstrated a similar efficacy between equal concentrations of ropivacaine and bupivacaine. In addition, increasing the concentration of ropivacaine from 0.5% to 0.75% fails to improve the onset or duration of interscalene brachial plexus block.

Comparative study of reductive amination reaction on 5-(4-formyl-3,5-dimethoxyphenoxy)valeric acid and its monomethoxy analog using the Multipin approach.

The 5-(4-formyl-3,5-dimethoxyphenoxy)valeric acid (Barany) linker and its monomethoxy analog were applied to the Multipin method of solid phase synthesis. A comparative assessment of reductive amination and cleavage of these linkers under conditions of multiple synthesis indicated that both were applicable to a broad range of primary amines including aniline and 4-nitroaniline. Apart from the greater lability of the dimethoxy version under TFA cleavage, there was no observable advantage of one linker over the other within the described experiment.

Lumbar plexus and sciatic nerve block for knee arthroplasty: comparison of ropivacaine and bupivacaine.

PURPOSE: Information about the onset time and duration of action of ropivacaine during a combined lumbar plexus and sciatic nerve block is not available. This study compares bupivacaine and ropivacaine to determine the optimal long-acting local anaesthetic for lumbar plexus and sciatic nerve block in patients undergoing total knee arthroplasty. METHODS: Forty adult patients scheduled for unilateral total knee arthroplasty, under lumbar plexus and sciatic block were entered into this double-blind randomized study. Patients were assigned (20 per group) to receive lumbar plexus block using 30 ml of local anaesthetic and a sciatic nerve block using 15 ml of local anaesthetic with either bupivacaine 0.5% or ropivacaine 0.5%. All solutions contained fresh epinephrine in a 1:400,000 concentration. Every one minute after local anaesthetic injection, patients were assessed to determine loss of motor function and loss of pinprick sensation in the L1-S1 dermatomes. The time to request first analgesic was documented from the PCA pump. This time was used as evidence of block regression. RESULTS: Blocks failed in four patients in each group. The mean onset time of both motor and sensory blockade was between 14 and 18 min in both groups. Duration of sensory blockade was longer in the bupivacaine group, 17 +/- 3 hr, than in the ropivacaine group, 13 +/- 2 hr (P < 0.0001). CONCLUSION: We conclude that bupivacaine 0.5% and ropivacaine 0.5% have a similar onset of motor and sensory blockade when used for lumbar plexus and sciatic nerve block. Analgesic duration from bupivacaine 0.5% was prolonged by four hours compared with an equal volume of ropivacaine 0.5%.