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Biomedical subjects

M Knoch

Publications and source records attributed to M Knoch.

At least 19 recordsLinked to original sources
PubMed2000

Basis for nebulized antibiotics: droplet characterization and in vitro antimicrobial activity versus Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.

The aims of this study were to (1) quantify the particle size characteristics of several antibiotics considered suitable for aerosol therapy after aerosolization with the PARI IS/2 nebulizer (Pari GmbH, Sarnberg, Germany) and (2) determine the degree to which in vitro antimicrobial activity of these antibiotics is maintained after nebulization. The aerosolized drugs were tobramycin sulfate, streptomycin, and imipenem, with saline solution as the control. Mean mass aerodynamic diameter of the nebulized drugs was 3.25 microns for tobramycin, 2.26 microns for imipenem, and 2.38 microns for streptomycin. In vitro tests showed that tobramycin and imipenem were unaltered in their bacteriostatic activity against strains of Escherichia coli (American Type Culture Collection [ATCC] 25922) and Staphylococcus aureus (ATCC 29213) as well as against Pseudomonas aeruginosa (ATCC 27853) with minimal inhibitory concentration (MIC) values less than 0.3 microgram/mL. Nebulized streptomycin showed significantly higher MIC values against P. aeruginosa (ATCC 27853). These results suggest that tobramycin and imipenem may be prescribed as an aerosol generated by jet nebulization (PARI IS/2) to treat S. aureus, E. coli, and P. aeruginosa infections without any risk of altering the drugs minimum bacteriostatic activity by the nebulization process. Aerosolization of streptomycin with this nebulizer may not be as effective against P. aeruginosa because it seems to alter the bacteriostatic activity.

Aerosols↗
PubMed1997

[Percutaneous dilatative tracheostomy as a new method in intensive medicine. Procedure, advantages and risks].

BACKGROUND AND OBJECTIVE: Percutaneous dilatational tracheostomy (PDT) is a recently developed method to obtain endotracheal access, also at the bed-side, in ventilated patients. The procedure is described and results are presented. PATIENTS AND METHODS: PDT was performed in 112 patients (82 men, 30 women, average age 50.7 years) between 1.5. 1994 and 31.5. 1996, in all cases expected to require more than 10 days of assisted ventilation. All complications, late sequelae and cosmetic results after decannulation were analysed. RESULTS: No serious complications were noted during the procedure. Erroneous puncture occurred in nine patients, but were corrected without problem. Complications necessitating temporary interruption of the tracheostomy consisted of accidental extubation and ventilatory problems (two patients each). There were no late sequelae and the cosmetic results were judged to be very good. CONCLUSION: PDT is a simple and relatively easily learned procedure. It has a low complication rate, late sequelae are very rare and cosmetic results after closure of the tracheostomy are excellent.

Critical Care↗
PubMed1997

[Adrenal gland incidentaloma is not a "time bomb"--arguments for follow-up control].

Adrenal masses are nowadays more and more diagnosed incidentally. In the vast majority of cases these "incidentalomas" are benign adrenocortical adenomas which do not compel operative therapy. In about 12% of patients an endocrine activity is detected. With Increasing tumor size the risk of malignancy increases. This article summarizes recommendations, only to allow patients with endocrine activity or an increased risk of malignancy to be selected for surgery. A small uncertainty will always remain, but may be minimized by an individually tailored follow-up.

Adrenal Gland Neoplasms↗
PubMed1996

["Treatment of total atelectasis of the left lung in severe ARDS with side-separated ventilation and surfactant administration"].

Severe thoracic trauma is always an important risk factor for the development of acute pulmonary failure. The course is often complicated by barotrauma or volutrauma. We report on a 48-year-old patient who was transferred to us nine days after a bicycle accident because of a severe disturbance of gas exchange and atelectasis of the left lung refractory to therapy. The left lung could not be ventilated even after separate artificial ventilation on each side with positive end expiratory pressure. After administration of surfactant (50 mg Exosurf per kg body weight) and continued separate artificial ventilation on each side, there was a complete re-expansion of the left lung with an increase of the arterial pO2 value from 65 mm Hg to 416 mm Hg with a FIO2 of 1,0 and a decrease of the intrapulmonary venous admixture from 34% to 12% within a few hours. The extravascular pulmonary fluid was unaffected by the administration of surfactant (200 ml solution). The administration of surfactant preparations may be a new therapeutic approach in treatment of ARDS patients.

Combined Modality Therapy↗
PubMed1996

[Long-term survival after non-curative therapy of colorectal carcinomas].

In a total of 1073 unradically resected patients (R1/R2) surprisingly we found a group of 31 with a more than 5-year-survival and seven patients living more than 10 years. The prognosis in patients presenting rectal carcinoma was significantly better compared to colon cancer, with a 5-year-survival of 5 +/- 2% compared to 1 +/- 1%. For a long local control of tumor growth in the residual tumor patients, the possibility of irradiation probably in combination with chemotherapy seems to explain these data; but half of our longterm survivors had no additional therapy. The influence of tumorbiological and immunological factors in such patients are of further interest.

Adolescent↗
PubMed1995

Development, manufacturing and validation of a single-leaflet mechanical heart valve prosthesis.

A new single-leaflet mechanical heart valve prosthesis was developed and evaluated in vitro and in vivo. The basic design of the closing body is S-shaped, with the leading and trailing edges parallel to the flow direction. This closing body has an additional cross camber and a fixed axis of rotation. The bearing pins of the disc are guided within oblong through bores of the housing, resulting in a self-cleaning effect. The valve housing has a nozzle-shaped configuration in order to avoid flow separation at the inlet and to reduce the associated pressure loss. Development and optimization studies were carried out by means of upscale valve models. After manufacturing of the closing body from pyrolytic carbon and of the orifice from titanium final hydrodynamic evaluation was carried out according to ISO 5840. The results were comparable or better than for bileaflet valves, the cavitation threshold was above a left ventricular dP/dt of 5500 mmHg/sec. The excellent in vitro results were confirmed by in vivo animal studies in calves and sheep with implantation times of 12 months and six months, respectively. These studies were carried out at the RWTH Aachen and at the NIH, Washington. Without any anticoagulation treatment the valves showed excellent results, confirming the concept of a valve design based on advanced engineering techniques.

Animals↗
PubMed1994

A nebulizer system for highly reproducible aerosol delivery.

The output characteristics of current nebulizer systems are influenced by factors such as inspiratory flow, temperature and relative humidity of the ambient air as well as surface tension of the nebulizing solutions. Due to the resulting alteration of droplet characteristics the delivery of aerosolized drugs is variable. A nebulizer system, the PARI IS-2, has been designed for the delivery of aerosolized potent drugs. It is characterized by a highly consistent aerosol output and a high proportion of droplet mass in the respirable range. Laboratory testing was performed with a Malvern Particle Sizer and by measurement of total and effective output rates. Preconditioned air was supplied to the system in order to simulate different inspiratory flows (steady state) at varying ambient conditions. There was only a small effect on droplet sizes (MMD 3.0 to 3.6 microns) over the investigated range of inspiratory flow, ambient conditions and drug solutions. Total and effective output rates of the nebulizer were found to be linearly proportional between 5 and 20 l/min inspiratory flow thereby compensating for the dilution of aerosol by entrained air. Total output, at a relative humidity between 20% and 80% and at fixed inspiratory flow, varied only by +/- 6% with respect to 50% relative humidity (r.h.). The proportion of the dose delivered from the system ranged from 28% to 67% for an initial fill volume between 0.5 and 3 ml, respectively. Thus, for standardized breathing and by using the manual interrupter for on-command therapy, a highly effective delivery and deposition of therapeutic aerosols in the lungs may be achieved with the PARI IS-2 nebulizer system.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1994

Efficient drug delivery to the lungs from a continuously operated open-vent nebulizer and low pressure compressor system.

A comparison of aerosol delivery has been made between two open-vent Pari jet nebulizers. Intermittent and continuous delivery were compared for one of the nebulizers. Ten healthy volunteers inhaled 99mTc-labelled diethylenetriamine penta-acetic acid (DTPA) aerosols on three occasions. The Pari LC device was operated both intermittently (by a manual interrupter that generated aerosol only in synchrony with inhalation) and continuously. The Pari LL nebulizer was operated only in the intermittent mode. A system of inspiratory and expiratory valves was fitted to each nebulizer in order to direct airflow. Both nebulizers were powered by Pari Boy compressors. The mean (SD) whole lung deposition for the LL nebulizer was 11.1 (4.0)% of the nominal dose, compared to 15.3 (12.8)% and 12.8 (7.9)% for the LC used with intermittent and continuous operation, respectively. These differences were not statistically significant. Regional deposition patterns within the lungs were similar for the three nebulizer systems. These data show that efficient nebulizer systems using relatively low power compressors are possible, and suggest that continuously operated open-vent nebulizers may be designed to give lung deposition comparable to that achieved by nebulizers fitted with manual interrupters.

Administration, Inhalation↗
PubMed1993

Lung deposition from four nebulizers.

The total and regional deposition of aerosol has been compared using four nebulizers; the Pari Boy 37.80, Pari IS-2, RespirGard II and Penta-Sonic. The aerosol was radiolabelled with [99Tcm]DTPA, administered to ten healthy subjects and the distributions monitored by gamma scintigraphy. Median lung aerosol depositions expressed as percentages of the doses initially loaded into the nebulizers were: Pari IS-2 19%, Pari Boy 37.80 13%, RespirGard II 9% and Penta-Sonic 2%. The ratios of the peripheral to central lung deposition, however, were greater with the RespirGard II and Penta-Sonic nebulizers. The choice of the most appropriate nebulizer depends on the pharmaceutical being administered, since aerosol must be delivered to the required site in sufficient quantity, whilst minimizing the incidence of local or systemic side-effects.

Administration, Inhalation↗
PubMed1993

[The laryngeal mask versus intubation in difficult intubation conditions in the Franceschetti-Zwahlen-Klein syndrome (Treacher-Collins syndrome)].

A twenty-nine-year-old man suffering from Franceschetti syndrome requiring a retinal detachment operation was successfully anaesthetised using the laryngeal mask airway. The laryngeal mask has many advantages compared to endotracheal intubation in patients suffering from craniofacial abnormalities i.e. hypoplasia of the mandibular bone and ventral position of the larynx. In these cases the laryngeal mask is easily placed. However, the facilities of fibreoptic bronchoscopy should be readily available. The physician should have gained confidence in using a laryngeal mask before employing this device in cases of difficult intubation.

Adult↗
PubMed1993

A new aerosol device for bronchial provocation tests.

A special new device for diagnostic (bronchoprovocation) and therapeutic aerosol application is described. It consists of a high quality nebulizer system combined with a 10-liter storage bag which serves as an aerosol 'conditioner' (saturated ambient temperature and pressure conditions) and as a holding chamber to increase the respirable aerosol fraction and hence pulmonary deposition (Pari Provocation Test I). It allows ten times better standardized pulmonary aerosol deposition compared with the generally used nebulizers for calculation of dose-response curves especially for asthma provocation and dilatation tests. If slow inspiratory vital capacity maneuvers are used, pulmonary deposition of about 100 mg aerosol is achieved in children and adults. This device is especially important when exact dosing (also for therapeutic reasons) is required in the expanding field of topical and systemic aerosol application to or via the lung.

Aerosols↗
PubMed1993

A new oxygen applicator for simultaneous mouth and nose breathing.

We have developed a new O2 applicator to try to overcome the problems of long-term oxygen therapy that ensures a sufficient oxygen supply for both nasal and oral breathing and prevents mucosal irritation. Placed on the upper lip, it is unobtrusive. The principle is as follows: due to an enlarged outlet area, turbulence occurs and the oxygen is reduced. Thus, an oxygen cloud is formed that can be inhaled by both mouth or nose. The efficiency of our O2 applicator was compared with a face mask in six healthy subjects and patients with COPD. A similar increase in PO2 was found up to an oxygen flow of 2 L/min for nasal and oral breathing. Mild hypercapnia resulted in three patients with COPD only when a face mask was used and only when patients breathed through the nose. All patients preferred the new applicator.

Adult↗
PubMed1992

Morphometry of parenchymal and vascular alterations in ARDS after extracorporal carbon dioxide removal therapy (ECCO2-R-therapy).

The lungs of 12 patients suffering from ARDS treated by ECCO2-R-therapy were examined. The thickness of the interlobular septa, area portions of honeycombing, bleeding and lung parenchyma with diffuse alveolar damage were assessed by semi-automatic image analysis. Medial thickness of the pulmonary arteries with an external radius ranging between 40 microns and 150 microns was assessed planimetrically. The area portion of honeycombing ranged from 0% to 66% (average: 28.8%, standard deviation: 17.0%). The thickness of interlobular septa was increased with values between 74.0 microns and 195.5 microns (average: 140.4 microns, standard deviation: 41.7 microns; normal controls: 72.0 microns +/- 19.5 microns). Parenchymal and vascular changes were closely related: Average medial thickness rose from nearly normal values (4.9%) in cases with low area portions of honeycombing and bleeding to the double (11.1%) of normal values in cases with area portions of honeycombing and bleeding greater than 40%. We conclude that parenchymal changes due to shock and high inspiratory O2 concentration lead to changes of the pulmonary arterial hemodynamics which result in a quickly developing medial hypertrophy.

Adolescent↗
PubMed1992

[Acute respiratory failure--support of gas exchange using extracorporeal or implanted oxygenators--present status and future development].

In acute respiratory failure gas exchange can be supported or even maintained in an "alternative" way to mechanical ventilation using extracorporeal techniques (extracorporeal membrane oxygenation ECMO, extracorporeal CO2-removal ECCO2R), or intravenacaval oxygenators (IVOX). These techniques, which are currently in use in neonatology, pediatrics, and adult intensive care medicine, or techniques at present in clinical evaluation (IVOX), are reviewed with their indications, contraindications, differences, problems, worldwide results, and possible future applications.

Acute Disease↗
PubMed1992

[Pulmonary function one year after extracorporeal lung assist. A long-term follow-up of patients with acute adult respiratory distress syndrome].

This retrospective follow-up studied lung function and reconvalescence in 38 young patients without primary lung disease, who suffered from severe ARDS and survived by means of extracorporeal lung assist (ELA) treatment. Over a period of 3, 6, 9 and 12-20 months dynamic and static lung volumes and the results of X-ray and CT scan of the thorax were studied. Within the third and sixth month the forced vital capacity, FEV1, and arterial blood gases reached the lower range of normal values. Obvious relative emphysema RV/TLC was observed at the time of discharge from hospital and during the first four months. This was found to reverse during the following months. After a period of 12-20 months all patients had an abnormal diffusion capacity (TLCO) but with normal transfer coefficients (TLCO/VA). Even though ARDS did not induce obstructive changes, the diminished diffusion capacity and the slightly reduced expiratory peak flow in 25-75% of FVC (FEF 25-75) indicates slight changes in the small airways. Following up the X-ray and CT results we found extraordinary morphological restitution. Spiroergometry results showed a normal cardiopulmonary pattern for untrained individuals. 36 of the 38 patients were integrated in normal working and social life within 12-20 months.

Adolescent↗
PubMed1992

[Waste water pollutants due to the use of disinfectants in the hospital].

It is assumed that the antiseptic effect of disinfectants in effluents from hospitals can severely disturb the growth of microorganisms in the different stages of aeration of sewage plants. Regular biological catabolism could therefore be damaged. The impact of substances on the waste water depends on the concentration of disinfectants they contain. Consequently this essay first examines the expected quantities of antiseptic substances in the effluent of a medium-sized hospital (440 Beds). The effluents treated here however showed a low concentration of disinfectants and it could be proved that these quantities do not have any harmful effects on the examined parameters such as BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand) and pH-value.

Disinfectants↗
PubMed1992

Progress in veno-venous long-term bypass techniques for the treatment of ARDS. Controlled clinical trial with the heparin-coated bypass circuit.

Extracorporeal CO2 removal combined with low-frequency positive pressure ventilation (ECCO2-R LFPPV) is a new therapeutic approach in treatment of ARDS. The main problem during long-term extracorporeal support is anticoagulation and related bleeding problems. We conducted a prospective, randomized and controlled clinical trial in 18 patients to compare the effect of the non-heparin-coated (Scimed = group 1) with the heparin-coated (Carmeda = group 2) extracorporeal circuit on clinical course and complication rate. In group 2 the daily blood loss, the amount of substituted red cells and the i.v. heparin dose were significantly lower than in group 1. Bleeding complications were less and more patients survived in group 2. The disadvantage of the hollow fiber oxygenators in the heparin-coated system was plasma leakage, which was more frequent in patients with pancreatitis and hyperbilirubinemia.

Adolescent↗