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W Armbruster

Publications and source records attributed to W Armbruster.

14 recordsLinked to original sources
PubMed2004

Observations on intraoperative monitoring of visual pathways using steady-state visual evoked potentials.

BACKGROUND AND OBJECTIVE: Former studies revealed conflicting information on the usefulness of intraoperative monitoring of visual evoked potentials. This study was designed to evaluate the characteristics of visual evoked potential recording in surgically anaesthetized patients using the modality of steady-state visual evoked potentials. METHODS: In 30 cases with non-cranial surgery steady-state visual evoked potentials were recorded in the awake and surgically anaesthetized patient using total intravenous anaesthesia. For stimulation, goggles with red light-emitting diodes at a frequency of 8.5 Hz were used. A two-channel recording with silver cup electrodes at Oz to Fz and Oz to earlobe was used. All traces were analysed for the presence of the characteristically sinusoidal waveform and amplitudes and latencies of the main peaks were measured. RESULTS: Recordings during surgery demonstrated a minor latency prolongation of 16% and a more pronounced amplitude attenuation of 67% compared to the recordings in the awake patients. These differences were statistically significant (paired t-test, P < 0.001). In surgically anaesthetized patients steady-state visual evoked potentials showed a relatively high intra- and interindividual variability. In four of 30 patients completely stable recordings were obtained, whereas in 14 patients identifiable waves were recordable in only less than 50% of the intraoperative traces. Of the total 1360 traces recorded intraoperatively clearly identifiable steady-state visual evoked potentials patterns were present in 56% of the traces. There was no correlation between the magnitude of the evoked potential amplitude and its stability in intraoperative recordings. CONCLUSIONS: We conclude from this study, that steady-state visual evoked potential recordings in the surgically anaesthetized patient appeared to be more stable compared to our earlier findings using transient visual evoked potentials. However, further efforts are necessary to improve the stability of the recordings during surgery and thus allow for a more reliable intraoperative monitoring of visual pathways in routine clinical practice.

Adult↗
PubMed2004

False negative findings in intraoperative SEP monitoring: analysis of 658 consecutive neurosurgical cases and review of published reports.

OBJECTIVES: To determine the sensitivity of intraoperative monitoring in neurosurgical operations using somatosensory evoked potentials and to identify reasons for false negative findings and possible settings with an increased risk for monitoring failure. METHODS: SEP monitoring of 658 neurosurgical operations was analysed. The target of monitoring was the function of a hemisphere in 251 cases, the brain stem in 198 cases, and the spinal cord in 209 cases. RESULTS: In 27 cases (4.1%), monitoring was classified as false negative. Further analysis showed that five of these patients had experienced delayed neurological damage. Among the remaining 22 false negative cases, 14 had a minor neurological deficit and eight had severe neurological damage. Overall sensitivity and negative predictive value of SEP monitoring was 79% and 96%, respectively. For the detection of severe neurological damage the corresponding figures were 91% and 98%. Sensitivity of monitoring varied depending on the target of monitoring and the type of lesion. Monitoring was less likely to detect neurological damage in surgery for infratentorial tumours with brain stem compression, small lesions of the motor cortex, and small vessel damage during aneurysm surgery. CONCLUSIONS: SEP monitoring has acceptable sensitivity for detecting neurological damage during different neurosurgical procedures. Distinct settings with an increased risk of monitoring failure can be identified. In these cases measures to enhance the sensitivity of monitoring should be considered.

Adolescent↗
PubMed2003

[Blocking nociceptive afferents by retrobulbar bupivacaine does not decrease nausea and vomiting after propofol-remifentanil anaesthesia].

UNLABELLED: To test whether prophylactic neural blockade of noziceptive afferents or antiemetics diminutes postoperative nausea and vomiting (PONV) we studied in a randomised, prospective, and ouble-blind fashion 102 patients receiving implantation of an episcleral radioactive applicator for treatment of ocular malignant melanoma during remifentanil-propofol-anaesthesia. METHODS: 15 minutes prior to induction Dolasetron 12.5 mg (n = 18) or 50 mg (n = 20), Ondansetron 8 mg (n = 18), Droperidol 20 microg/kg (n = 23) or NaCl 0.9 % (n = 22) were randomly injected i.v. Furthermore, 4-8 ml Mepivacain 2 %/Bupivacain 0.5 % (n = 52) or saline (n = 50) were injected into the retrobulbar space after anaesthetic induction. Piritramid (0.1 mg/kg) was given for postoperative analgesia 30 minutes before end of surgery. Metamizol (1 g i.v.) and Dolasetron (12.5 mg i.v.) were provided on request as "rescue" medications. Variables were assessed by standardised questioning (NRS; yes/no) before and 1, 6, and 24 hours after surgery. STATISTICS: Chi(2)-, Mann-Whitney-U-, Kruskal-Wallis-test and logistic regression analysis, p < 0.05. RESULTS: Although retrobulbar anaesthesia decreased ocular pain (p = 0.013) and total postoperative complaints (p = 0.017) the incidence of PONV was not diminished. Droperidol was the only antiemetic to decrease PONV significantly (p = 0.001). CONCLUSIONS: Although prophylactic blockade of nozizeptive afferents by retrobulbar anesthesia decreased ocular pain and postoperative complaints, it failed to decrease the incidence of PONV. Thus, PONV after ocular surgery under propofol-remifentanil anaesthesia is not attenuated by preoperative blockade of noziceptive afferents. In patients undergoing total intravenous anaesthesia with propofol-remifentanil, droperidol prevented PONV more effectively than the used serotonin receptor antagonists.

Aged↗
PubMed2003

Visual evoked potentials for intraoperative neurophysiologic monitoring using total intravenous anesthesia.

Conflicting reports on the usefulness of intraoperative monitoring of visual function by means of visual evoked potentials (VEPs) initiated this study. In 32 patients without visual problems, VEPs were recorded to evaluate the reliability for intraoperative monitoring with total intravenous anesthesia. All patients underwent noncranial surgery. Using a standard technique, VEPs were recorded preoperatively in the awake patients and after induction of anesthesia during surgery. A total of 1436 intraoperative traces were recorded and analyzed. A minor prolongation of the P100 latency of 8% and a more pronounced attenuation of the P100-N145 amplitude of 60% were observed in the anesthetized patients. In most of the anesthetized patients, a stable recording of VEPs was not obtainable. In 4 patients (12.5%), clearly identifiable VEP peaks were detected in more than 90% of the traces recorded intraoperatively. In 88% of the patients, reproducible VEPs were obtained in less than 75% of the intraoperative traces only. We concluded that with standard recording techniques and total intravenous anesthesia, intraoperative VEP monitoring in surgically anesthetized patients is not reliable.

Adult↗
PubMed2002

Observations on intraoperative somatosensory evoked potential (SEP) monitoring in the semi-sitting position.

BACKGROUND: Former case reports suggest that monitoring of median nerve somatosensory evoked potentials (M-SEP) is unreliable in patients operated in the semi-sitting position due to the occurrence of evoked potential changes unrelated to neurological damage. This study was designed to analyze these changes in greater detail and confirm that these changes are not caused by neurological damage. METHODS: M-SEP monitoring findings of 50 patients with surgery in the semi-sitting position were analyzed and compared with a group of 50 patients who underwent surgery in the supine position. M-SEP amplitudes and latencies at distinct steps of the monitoring procedure were used for further analysis. In 10 of the 50 semi-sitting patients, M-SEP were recorded additionally after surgery with the anesthetized patient in the supine position. RESULTS: Significant M-SEP changes occurred in the semi-sitting patients only. An amplitude loss of greater than 50% on at least one side was observed in 24 patients. The magnitude and the time course of the amplitude loss was considerably variable. A complete loss of the evoked potential was not observed in any case. In all 10 patients, M-SEP recovered completely when recorded in the supine position. CONCLUSIONS: In about half of the patients with M-SEP monitoring in the semi-sitting position, a significant amplitude loss occurs which is unrelated to neurological damage and presumably caused by subdural gas collections. There is no characteristic pattern of M-SEP changes which enables a differentiation of these 'artificial' alterations from true events. The only appropriate criterion to indicate an impending neurological damage in these patients seems to be a complete loss of the M-SEP potential.

Adolescent↗
PubMed2002

Optimal rocuronium dose for intubation during inhalation induction with sevoflurane in children.

BACKGROUND: We studied 120 children aged 2-7 yr in a prospective, randomized, assessor-blinded fashion to define the optimal rocuronium dose which provides a 95% probability of acceptable intubation conditions (ED95TI) during inhalation induction with sevoflurane. METHODS: After inhalation induction with 8% sevoflurane in 60% nitrous oxide and 40% oxygen, and loss of the eyelash reflex, we administered rocuronium (0.1, 0.15, 0.22, 0.3, or 0.6 mg kg-1) or placebo. We quantified neuromuscular function by stimulation of the ulnar nerve at 0.1 Hz to produce contraction of the adductor pollicis muscle using accelerometry. Intubation conditions were assessed 2 min after test drug injection. The optimal rocuronium dose was defined as the lowest dose, which allowed acceptable intubation conditions in 95% of children (ED95TI). RESULTS: Two minutes after injection of placebo or rocuronium, intubation conditions were acceptable in 35, 45, 80, 90, 95, and 100% of children, respectively. Rocuronium 0.07 [CI 0.02-0.11], 0.24 [0.19-0.31], and 0.29 [0.23-0.38] mg kg-1 provided 50, 90, and 95% probability of acceptable intubating conditions. When thumb acceleration was depressed by 50% or more, intubating conditions were considered acceptable in 97% of children. Recovery of the train-of-four ratio to 0.8 averaged 12 (7), 16 (7), 24 (7), 24 (8), and 50 (22) min after the respective dose of rocuronium. CONCLUSIONS: During inhalation induction with 8% sevoflurane in 60% nitrous oxide, rocuronium 0.29 mg kg-1 (ED95) optimizes intubation conditions for surgery of short duration.

Androstanols↗
PubMed2001

Isolation and identification of N-mercapto-4-formylcarbostyril, an antibiotic produced by Pseudomonas fluorescens.

Pseudomonas fluorescens strain G308 isolated from barley leaves produces a novel antibiotic substance that was purified by preparative TLC and HPLC and identified as N-mercapto-4-formylcarbostyril (Cbs) by LC/DAD, IR, LC-ES(+)/MS, LC-ES(-)/MS, GC-EI/MS, LC-HRES(+)/MS, mass isotope ratios analysis, 1H NMR and 13C NMR analysis. The purified new antibiotic compound is effective against many phytopathogenic fungi in vitro. The compound inhibited at 25 ppm spore germination and germ tube growth of the following fungi; Fusarium oxysporum f. sp. lycopersici, Fusarium culmorum, Cladosporium cucumerinum and Colletotrichum lagenarium. At concentrations up to 125 ppm, the compound did not interfere with release of zoospores from sporangia and germination of encysted zoospores of Phytophthora infestans.

Antifungal Agents↗
PubMed1997

Hemofiltration increases IL-6 clearance in early systemic inflammatory response syndrome but does not alter IL-6 and TNF alpha plasma concentrations.

OBJECTIVE: To test the hypothesis that continuous hemofiltration increases interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF alpha) clearances and results in decreased cytokine plasma concentrations independent of renal function in patients with early SIRS. DESIGN: Prospective, controlled, randomized study. SETTING: Intensive care units at a university hospital. PATIENTS: 28 consecutive patients who fulfilled the criteria of the systemic inflammatory response syndrome (SIRS). INTERVENTIONS: Patients with SIRS were randomly assigned to either a hemofiltration or a control group irrespective of renal function. In patients of the hemofiltration group an isovolemic hemofiltration was initiated directly after the diagnosis of SIRS and maintained for at least 48 h. MEASUREMENTS AND RESULTS: A significant (p < 0.001) increase in total IL-6 clearance (hemofiltrate + urine), but not in TNF alpha clearance, was observed with hemofiltration. However, the plasma concentrations of both cytokines remained unchanged. Hemodynamic variables did not change significantly. CONCLUSIONS: Continuous hemofiltration increases IL-6 plasma clearance but not TNF alpha clearance. However, hemofiltration failed to decrease plasma concentrations of TNF alpha and IL-6 and, therefore, cannot be used effectively for cytokine elimination in SIRS. Accordingly, beneficial effects occasionally reported with hemofiltration are unlikely to be expected due to elimination of IL-6 or TNF alpha.

Adult↗
PubMed1997

Nasal turbinate dislocation caused by nasotracheal intubation.

A case of nasal turbinate dislocation secondary to nasotracheal intubation is presented. Although mild epistaxis had occurred in the days following extubation, the complication was not recognized until after the patient presented with headache and impairment of nasal breathing 6 months later. Endoscopy revealed the dislocation of the middle turbinate into the nasopharynx. Treatment by resection of the dislodged turbinate resulted in relief of symptoms. Physicians should be aware of the possibility of severe nasal damage following even apparently uncomplicated intubation and obtain consultation by an otorhinolaryngologist after epistaxis or obstructed nasal breathing.

Airway Obstruction↗
PubMed1993

Multidisciplinary rehabilitation of chronic work-related upper extremity disorders. Long-term effects.

The prevalence of work-related upper extremity disorders has significantly increased in the past decade. Persistent pain, loss of function, and associated work disability in patients with work-related upper extremity disorders appears to be affected by multiple factors including physical capabilities in relation to work demands, ergonomic risk factors on the job, and psychological factors related to worker traits, psychological readiness to return to work, and ability to manage symptoms. The complex nature of these disorders suggests the utility of a multidisciplinary program targeted at these factors. The present study is an investigation of the long-term vocational outcome of a multicomponent rehabilitation program that includes physical conditioning, work conditioning, work-related pain and stress management, ergonomic consultation, and vocational counseling/placement. Two groups equivalent on measures of duration of work disability, pain severity, fear of reinjury, psychological distress, perceived work environment, age, and education level were exposed to either the comprehensive work rehabilitation intervention (n = 19) or usual care (n = 15). Return-to-work status was determined at an average of 17 months posttreatment (range, 3 to 35 months) for the treatment group and an average of 18 months postevaluation (range, 5 to 30 months) for the usual care group. Findings indicated that 74% of the treatment group returned to work or were involved in state-supported vocational training in contrast to 40% of the control group (P < .05). For those who returned to work, 91% of the treatment group were working full-time in contrast to 50% of the control group (P < .05). Although the treatment group demonstrated a higher return-to-work rate than controls, the work reentry rate was not as high as similar approaches with work-related low back pain (80% to 88% return-to-work rate). These findings suggest the need to modify treatment components to facilitate an increased return-to-work rate. Areas that may prove useful include a greater emphasis ergonomic modifications at the workplace to reduce the risks of repetitiveness, force, awkward posture, and insufficient work/rest cycles, as well as efforts to modify work style directly in order to reduce the impact of ergonomic stressors on the ability to perform essential job tasks. In combination with traditional work hardening efforts directed at improving strength and flexibility of the upper extremities and work-related pain and stress management training, these ergonomic and work-style modification efforts may contribute to increases in the percentage of work disabled cases who successfully return to competitive work.

Arm Injuries↗
PubMed1984

[Multicenter study of the results of the extraction of transvenously implanted heart-pacemaker electrodes using continuous traction].

The continuous traction of firmly grown-in collar electrodes from the right ventricle is a simple technique poor in complications with a high success rate, which can be recommended taking into consideration the indications in the failure of the immediate manual extraction and which can be performed in every centre for cardiac pacemakers. Apart from the consideration of adequate informations in literature this evidence above all depends on the evaluation of data of 29 cases from 10 centres for cardiac pacemakers.

Adult↗
PubMedDate not supplied

Perforation of the posterior tracheal wall during percutaneous dilatational tracheotomy.

Dilatative percutaneous tracheotomy is more and more indicated in intensive-care medicine. We report on the perforation of the posterior tracheal wall observed in 3 patients after this procedure. In 2 patients the tracheo-oesophageal fistula was closed by the use of a pediculated flap from the infrahyoideal muscle. The third patient died due to the underlying disease. As demonstrated by the 3 cases reported here, this complication cannot be avoided in every case neither by the use of an endoscope nor by extensive personal experience of the physician. The possibility of this complication should be known, because it seems to be typical of this procedure. In the case of perforation of the posterior tracheal wall, active surgical treatment seems to be a successful method to deal with this complication.

Adolescent↗